WO2016041044A1 - Process for production of silicon-integrated iii-v optoelectronic devices - Google Patents

Process for production of silicon-integrated iii-v optoelectronic devices Download PDF

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WO2016041044A1
WO2016041044A1 PCT/BR2015/050157 BR2015050157W WO2016041044A1 WO 2016041044 A1 WO2016041044 A1 WO 2016041044A1 BR 2015050157 W BR2015050157 W BR 2015050157W WO 2016041044 A1 WO2016041044 A1 WO 2016041044A1
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substrate
process according
sacrificial layer
thin film
semiconductor
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French (fr)
Portuguese (pt)
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Christoph FRIEDRICH DENEKE
Saimon FILIPE COVRE DA SILVA
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Centro Nacional De Pesquisa Em Energia E Materiais
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
    • H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/01—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate comprising only passive thin-film or thick-film elements formed on a common insulating substrate

Definitions

  • the present invention represents a process for producing integrated semiconductor optoelectronic devices which relates to: (i) the use of transferred membranes as virtual substrates for the growth of epitaxial heterostructures on Si substrates; (ii) the production of semiconductor optoelectronic devices from the deposition of materials on thin films of compounds III-V after the transfer of thin films to Si substrates; (iii) the integration of semiconductor optoelectronic devices with Si substrates.
  • This patent describes a process for manufacturing integrated thin film semiconductor devices. To understand the innovative character of the invention, one needs to be familiar with the classical manufacturing processes of integrated semiconductor devices and the physical concepts on which they are based.
  • Semiconductor materials may be intrinsic in nature or may be extrinsic, physically or chemically modified to exhibit enhanced electronic properties.
  • the two most commonly used processes for modifying the electronic properties of a semiconductor material are: (i) doping, which occurs by the addition of "impurities” such as In or P to the crystal structure of intrinsic semiconductors such as Si and Ge; or (ii) the junction or junction, which It is the modification of properties by joining different materials.
  • a thin film refers to a layer of material attached to a substrate in which the width and length are much greater than the thickness in the nanometer range.
  • nanomembrane designates a free thin film, that is, loosened or loosely attached to a substrate.
  • MBE Molecular Beam Epitaxy
  • MBE is a crystal growth technique from the evaporation of chemicals in an ultra high vacuum (3 ⁇ 4 10 ⁇ 10 Torr) environment that ensures the integrity of incident beams during growth and limits impurity levels. that may be incorporated into the samples.
  • the MBE technique is capable of producing monocrystalline layers on atomic precision substrates, allowing the fabrication of semiconductor nanostructures capable of meeting the growing technological demands of current optoelectronic emission and absorption devices.
  • Commercial examples of such devices include solar cells, LEDs and lasers.
  • the substrate constituent material must be compatible with the constituent elements of the films to be deposited thereon, among other restrictions.
  • the choice of the best substrate for a given device depends on its final application, the growth rate of the film (s) and the need for the highest quality device with the least amount of mechanical or structural defects. Although these are the main considerations in choosing the substrate, the state of the art shows that other factors must also be evaluated for decision making.
  • Substrate cost is a restrictive but non-determining factor for selection of precursor materials.
  • high purity monocrystalline substrates are used which tend to be very expensive except for the use of abundant and widely available materials such as silicon.
  • Polycrystalline materials have lower cost, but are not used as substrates for epitaxy processes.
  • the substrate must also exhibit good thermal stability, because crystal processing often occurs at high temperatures, which may reach up to 900 ° C; therefore the substrate must remain stable over the entire temperature range throughout processing.
  • the thermal expansion properties of the substrate and thin film should be compatible as high temperature crystal processing requires the substrate and film to expand and contract in a similar manner, preventing crystal breakage after cooling. .
  • Substrate brittleness should be considered, because an important function of the substrate is to support the thin film. If the substrate itself is fragile, the overall structure may have an unacceptably high level of fragility, compromising its application.
  • the interdiffusion between the substrate and the thin film film should be as small as possible so that there are no defects and changes in electrical and optical properties in the interface regions, which can be reviewed in detail in Chapter 5 of Callister et al. .
  • the dielectric constant of the substrate must be chosen carefully according to the final application of the device. Acceptable substrates for the reasons described above, if they have a very high dielectric constant, may be unsuitable for applications involving dielectric effects, microwaves, as the substrate dielectric constant will strongly affect the overall dielectric constant of the semiconductor device produced.
  • Si substrates are plentiful, cheap and easy to produce. However, these substrates have an indirect energy gap and low load carrier mobility. In addition, Si substrates are incompatible with many networks, including III-V compounds, representing obstacles to the manufacture of low-cost, high-performance optical devices.
  • a buffer layer is an intermediate layer arranged between the substrate and the desired film. Provided they are properly chosen, buffer layers are advantageous because they tend to prevent interdiffusion between the substrate and the film and even out the incompatibility of the networks. However, the decision to use buffer layers must be carefully evaluated because they can solve film tension / relaxation problems, but simultaneously can create thermal expansion problems, increase production costs and increase the dielectric constant of the device. In addition, buffer layers are very specific solutions that suit a particular substrate / film combination and are not a global solution.
  • US 7,202,503 describes an example of using a buffer layer under direct thin-film growth conditions, making a transition from Si to Ge, that is, using an intermediate layer of a compound III-V or II-VI having a parameter intermediate network between Si substrate and Ge film.
  • US 7,214,598 discloses a process in which between the Si substrate and the SiGe film a SiGe buffer layer is used which has an increasing concentration of Ge ranging linearly from 0% (near the Si substrate) to 50%. % (next to SiGe movie).
  • a second process, illustrated in the schematic representation of Figure 2 is the transfer of the ready device to a new substrate after its growth on a sacrificial layer, removed by the known epitaxial lift-off (ELO) technique.
  • ELO epitaxial lift-off
  • the device produced by the post-transfer process would have superior performance and functionality than the optical and electrical circuits taken separately, but this process has intrinsic problems linked to the integrability of the devices, ie it does not allow integration of optics and electronics into the same substrate, especially with Si substrates.
  • the physical properties of Si such as its indirect energy gap and low load carrier mobility, represent obstacles to the successful production of photonic devices with this substrate. process.
  • the present invention proposes an innovative solution to circumvent the above integration, compatibility and growth rate problems for Si substrates by using a transferred thin film, called virtual substrate, which makes it possible to manufacture more efficiently. a range of high quality devices integrated with Si substrates.
  • the present suggested process advantageously allows the manufacture of a substrate ready for epitaxial growth of various devices via direct growth technique, suppressing network incompatibility or thermal expansion problems.
  • the present process considers the transfer of a nanomembrane to the Si substrate and the deposition of heterostructures of III-V compounds on the virtual substrate, thus avoiding the disadvantages presented by the direct growth of III-V materials on bulk substrates. commonly caused by the difference between your network parameters.
  • the direct device growth on this virtual substrate avoids the disadvantage of ready device transfer after its growth, especially its degeneration during the lift-off epitaxial process.
  • Transferred layers may be electrically contacted with the substrate, for example, due to the interdiffusion of the metal layer, as used in conventional semiconductor technology, before or after device growth.
  • the virtual substrate can be positioned on the new substrate to allow its integration with the previously defined semiconductor circuits. on the new substrate.
  • the present invention represents a novel process for the growth of epitaxial III-V heterostructures on nanomembranes transferred to Si substrates for the manufacture of high quality optoelectronic devices such as LEDs and lasers.
  • the basis of the process is the deposition of a sacrificial layer and a thin film of material III-V on an appropriate substrate from any known epitaxial deposition technique.
  • an applicable technique is Molecular Beam Epitaxy or Molecular Beam Epitaxy (MBE).
  • MBE Molecular Beam Epitaxy
  • the sacrificial layer is removed by wet etching and the free thin film is transferred to a new substrate, preferably Si, and electronically integrated to it.
  • the thin film now acts as a virtual substrate and the thin film and Si substrate assembly is suitable for direct growth of various optoelectronic devices by known processes and applied in the state of the art.
  • One of the typical uses of this invention is in the growth of the structure of vertical cavity and surface emission lasers (VCSEL), intended for optical communication, high resolution TV systems, control and sensing of physical and chemical quantities, applications. medical and automotive components.
  • VCSEL vertical cavity and surface emission lasers
  • Figure 1 is a schematic representation of the direct growth process of state of the art semiconductor devices.
  • Figure 2 is a schematic representation of the growth and post-transfer process of state of the art semiconductor devices.
  • Figure 3 is a schematic representation of the growth and transfer process of semiconductor thin films, object of the present invention.
  • Figure 4 is a series of optical microscopy images of the steps of the semiconductor thin film transfer process, object of the present invention.
  • Figure 5 is an atomic force microscopy of the virtual substrate of the semiconductor device growth process, object of the present invention.
  • Figure 1 depicts the direct growth process of semiconductor devices on substrates.
  • Bulk substrate (1) may be chosen from an appropriate group of semiconductor materials including Si, GaAs, InP and others.
  • the direct deposition step (2) of the device is observed on the substrate and can be chosen from a group of known and state-of-the-art techniques including molecular beam epitaxy (MBE), chemical vapor deposition, spraying. cathodic or sputtering, among others.
  • MBE molecular beam epitaxy
  • the ready optoelectronic device (3) has application as diode, transistor or laser.
  • Figure 2 depicts the growth and post-transfer process of semiconductor devices on epitaxial lift-off substrates.
  • the bulk substrate (1) receives a sacrificial layer (4) which consists of materials such as AlAs, Si, SiO2, GaAs, among other semiconductors.
  • a sacrificial layer (4) which consists of materials such as AlAs, Si, SiO2, GaAs, among other semiconductors.
  • Several layers of the device are progressively deposited on the sacrificial layer (4) using techniques from the group including MBE, vapor phase chemical deposition, sputtering, among others, forming the heterostructure (5).
  • the ready optoelectronic device (3) is obtained by removing the sacrificial layer (4) by known state of the art techniques such as wet etching or plasma etching and its post-transfer to a new substrate.
  • Figure 3 demonstrates the process introduced by the present invention.
  • a sacrificial layer (4) of AlAs on a bulk substrate (1) of monocrystalline GaAs at a temperature between 400 C and 2 650 ° C.
  • an epitaxial deposition (2) is performed on the sacrificial layer (4) using techniques from the group including MBE, chemical vapor phase deposition, sputtering, among others, of semiconductor elements, which are incorporated into the layer. (4) and form a thin film (6).
  • 0 thin film (6) has a thickness less than 20 nm and is composed of III-V elements or combinations of alloys of different compositions, preferably Gai- x In x As, In x x Gai- AlAs, InGaAlP or InGaAlN.
  • the sacrificial layer (4) is then removed by one of the state-of-the-art etching techniques and the released thin film, sometimes called nanomembrane (8), is transferred to a new bulk substrate (7) selected from an appropriate group. semiconductor materials, preferably Si.
  • a suitable structure for epitaxial growth formed by the transferred nanomembrane (8), called virtual substrate (9), and the new substrate (7) is obtained.
  • This assembly (10), formed by the new bulk substrate (7) plus the transferred virtual substrate (9), can be used as the basis for the direct growth of any usual optoelectronic device by known semiconductor processing techniques.
  • the process can be broken down into steps that combine aspects of lift-off epitaxial and growth techniques. straightforward.
  • a sacrificial layer (4) with a thickness ranging from 4 nm to 2000 nm is grown so as to allow later lift-off and transfer of the layers to the new one.
  • a thin film (6) of compounds III-V comprising B, Al, Ga, In, T1, N, P, As, Sb, Bi and including their alloys and non-metallic.
  • the thickness of the upper layer is imposed on the condition that it is thinner than the critical thickness from which the formation of defects in the chosen epitaxial system begins.
  • a typical form of the invention is the deposition of a thin film of between 2 and 100 nm, preferably 10 nm, composed of Ino.33Gao.67As, grown on an AlAs sacrificial layer at a temperature between 400 and 400 ° C. 650 2 C.
  • the thin film (6) is released from the original bulk substrate (1) by selective removal of the sacrificial layer (4). During release, the thin film (6) relaxes and its mesh parameter equals that of its bulk shape, which may be smaller or larger than the mesh parameter of the original bulk substrate (1).
  • the lattice parameter of the new set (10) is independent of the new substrate (7) and is defined exclusively by the properties of the thin film, which is now called the transferred nanomembrane (8).
  • the network parameter is between 0. 583 nm and 0.601 nm, GaAs and InAs network parameters, respectively.
  • the relaxation process of this layer has already been studied and demonstrated by Mei et al.
  • the thin film (6) is then removed and transferred to the new substrate (7) according to Malachias et al.
  • the new substrate (7) should be suitable for direct growth and have the desired complementary properties to those of the thin film layer, then called nanomembrane (8) transferred.
  • a typical form of this invention uses silicon as new substrate (7), because it is a cheap, versatile substrate suitable for highly integrated circuits, and is the basis of modern computer technology.
  • Si is not the optimal substrate for optoelectronic device construction because of its indirect energy gap, but as noted in this paper, successful production of Si-integrated optical devices is of high interest. Transfer to substrates other than Si has been demonstrated by several authors, including the inventors of this invention, as shown in Malaquias et al.
  • the nanomembrane (8) is electrically connected to the substrate using a diffusion or direct bonding process.
  • the layer is precisely aligned to the new substrate (7), as demonstrated for Si by Kim et al.
  • layer III-V which is renamed virtual substrate being in the new substrate (7), is cleared. Cleaning should be done initially to remove the photoresist and then the oxides deposited on the surface of layer III-V.
  • Photoresist cleaning substances include solutions of sulfuric acid, SemiconClean 23 (Furuuchi Chemical Corporation), dimethyl sulfoxide and acetone.
  • the cleaning step further includes the use of atomic hydrogen or an oxide removal heat treatment. Deneke et al. describes well established bulk layer cleaning processes which are incorporated herein by reference and applied to the virtual substrate to enable direct growth of epitaxy devices onto the assembly (10).
  • the transferred nanomembrane (8) can be used as a virtual substrate for epitaxial growth of compounds III-V. This further process of direct growth on the virtual substrate is possible and is corroborated by results of studies not yet published by the inventors of this invention.
  • the set (10) may consist of different alloy compositions of compounds III-V and still exhibit different network parameter from common bulk substrates such as GaAs or InP. Accordingly, virtually any type of conventional optical-electronic device can be grown on the substrate by heteroepitaxial processes. Possible devices include the aforementioned telecommunications vertical cavity lasers (VCSEL), typically grown over InP, or high mobility electronic transistors (HEMT) for high speed electronics applications.
  • VCSEL vertical cavity lasers
  • HEMT high mobility electronic transistors
  • the devices can be fabricated over the grown heterostructure using well-established techniques for large-area industrial semiconductor processing that include lithography, reactive ion etching, ion implantation, and others.
  • Figure 4 shows a series of microscopy images referring to the steps of a preferred embodiment of the process of the present invention. From left to right are: standards set atop a heterostructure GaAs / AlAs / In x x The Gai- (11); the structure after the first wet etching that defined the trenches (12); substrate after lift-off epitaxial (13); substrate after nanomembrane transfer (14); nanomembranes in the new Si substrate (15,16).
  • Figure 5 shows an atomic force microscopy (AFM) image of the surface of an InGaAs membrane prepared by the post-growth technique shown in Figure
  • the following example describes the process step by step when employed in the growth of the structure of a vertical cavity and surface emission laser (VCSEL) on a Si substrate (7) covered by an InGaAs nanomebranch (8).
  • VCSEL vertical cavity and surface emission laser
  • This embodiment of the invention is illustrative only and in no hypothesis restricts its scope.
  • the process steps are generally similar for any other type of heterostructure, except for step VIII which may be changed depending on the nature of the heterostructure that is to be grown in the set (10).
  • Step I About a bulk substrate (1)
  • Commercial GaAs (001) suitable for epitaxial growth is grown heterostructure of one AlAs / x In x As Gai- using molecular beam epitaxy (MBE).
  • MBE molecular beam epitaxy
  • the GaAs substrate is heated to 600 ° C in the MBE equipment for removal of native oxides.
  • a 200 nm thick GaAs buffer layer is grown on the bulk substrate (1) following standard MBE growth procedures. After growth of the buffer layer, the substrate temperature is reduced to 500 ° C and a 20 nm AlAs sacrificial layer (4) followed by another layer, called Ino, 2Gao, sAs thin film (6). also at 20 nm (hereinafter referred to as InGaAs thin film (6)) are deposited on the buffer layer.
  • Step II The heterostructure is removed from the MBE chamber and a photolithography process is performed to define the patterns in the heterostructure. Circles approximately 150 ⁇ m in diameter are used as standards. By wet etching using a H2O2: H3PO: H2O solution (10: 1: 100 mass ratio) the patterns defined by photolithography are reproduced in the heterostructure. After etching, the photosensitive material (photoresist) remains in the structure over the thin film (6) of InGaAs.
  • Step III InGaAs thin film (6) is then released from the bulk substrate (1) by selective removal of the AlAs sacrificial layer (4) by wet-etching. AlAs are removed using a dilute HF solution known for high selectivity (epitaxial lift-off). During lift-off, although attached to the photoresist, InGaAs thin film (6) is relaxed as the photoresist is much more malleable than InGaAs. During the removal of the sacrificial layer (4) AlAs, the nanomembranes (8) fall to the GaAs substrate and are weakly bound to it.
  • Step IV Using a technique called soft-imprint lithography, nanomembrane (8) is transferred to a transport substrate selected from a material group that includes glass, silicon and any smooth, product-resistant materials used in steps V and VI. Initially the transport substrate is coated by the photoresist. Next, the photoresist-coated face is pressed against the bulk substrate (1) of GaAs and its nanomembrane (8) released from InGaAs. The photoresist acts as a glue, binding the membranes to the intermediate substrate. This process is illustrated in Figures 3 and 4, described in detail in the Detailed Description of Figures section.
  • Step V Now InGaAs nanomembrane (8) (with photoresist residues) on top of the transport substrate is pressed and transferred to a new substrate (7), in this case a Si wafer (001). A heat treatment ensures that InGaAs membrane (8) is bonded to the Si substrate.
  • the transport substrate is removed after photoresist removal, which is performed using a conventional photolithography remover such as DSMO or acetone.
  • Step VI To fit the final assembly (10) formed by the substrate Si (7) plus the transferred nanomembrane (8) to the epitaxial growth, the surface must be chemically cleaned.
  • a standard process, which does not attack the underlying Si substrate, is wet etching in H2SO4 for 10 minutes, water washing, etching for 2 minutes in SemiconClean 23 (Furuuchi Chemical Corporation), water washing for 10 minutes and drying. Set 10 is now ready for epitaxial growth.
  • Step VII Set (10) is reintroduced into the system for MBE deposition. Before the heterostructure is grown, an atomic hydrogen cleaning is performed to remove native oxide from InGaAs and other impurities. Epitaxial heterostructures can now be deposited on top of the assembly (10) using the methods described in the literature. Figure 5 shows the high quality of the nanomembrane surface (8) after cleaning and before growth.
  • Step VIII Growing a VCSEL structure over InGaAs requires some modifications to its usual components to fit the InGaAs relaxed membrane network parameter, however all components of the VCSEL structure can be grown over the virtual substrate (9). ).
  • the main structures are: (a) below, a Bragg mirror of an InGaAs / InAlGaAs superstructure; (b) in the active laser cavity, InAlGaAs / InGaAs / InAlGaAs structure and (c) at the top, a Bragg mirror from an InGaAs / InAlGaAs superstructure.
  • VCSEL can be replaced by any heterostructure, as the virtual substrate behaves as a suitable substrate for epitaxial growth.
  • Step IX After material deposition, an additional step is required for removal of the deposited material in areas not covered by the transferred nanomembrane. Therefore, a second lithography process should be done using the mask of the first process. Since the position of the InGaAs nanomembrane on the Si substrate is defined by the pattern of the first lithograph, only the correct alignment between the mask and the InGaAs nanomembrane is required. Areas with desired material can be photoresisted so that wet etching removes only material from areas not covered by the InGaAs membrane.

Abstract

The present invention relates to a process that allows the growth of integrated semiconductor devices of high quality, good efficiency and low cost on heterostructures of III-V materials on virtual substrates, prepared using epitaxial deposition techniques (2), such as MBE or chemical vapour phase deposition. The use of nanomembranes (8) as virtual substrates eliminates recurring problems encountered in the customary production of these devices, such as a lack of compatability between network parameters and thermal expansion coefficients, in the case of direct growth, and disintegration of the device during etching, encountered in the transfer of the prepared device by epitaxial lift-off. The process consists in the deposition of a sacrificial layer (4) and a thin film (6) on a suitable substrate (1). The sacrificial layer (6) is removed by wet etching and the free thin film, called the nanomembrane (8), is transferred to a new substrate (7), preferably an Si substrate. After electronic integration between the layers, the assembly (10) formed by the new substrate (7) and the nanomembrane is suitable for fabrication of conventional optoelectronic devices (3) such as lasers, transistors with high electron mobility and LEDs, using well-established semiconductor processing processes.

Description

PROCESSO PARA. PRODUÇÃO DE DISPOSITIVOS OPTOELETRONICOS III-V  PROCESS TO. PRODUCTION OF OPTOELETRONIC DEVICES III-V
INTEGRADOS EM SILÍCIO INTEGRATED IN SILENCE
CAMPO DA INVENÇÃO FIELD OF INVENTION
[001] A presente invenção representa um processo para produção de dispositivos integrados optoeletrônicos semicondutores que se refere: (i) ao uso de membranas transferidas como substratos virtuais para o crescimento de heteroestruturas epitaxiais em substratos de Si; (ii) à produção de dispositivos optoeletrônicos semicondutores a partir da deposição de materiais sobre filmes finos de compostos III-V após a transferência dos filmes finos para substratos de Si; (iii) à integração de dispositivos optoeletrônicos semicondutores a substratos de Si.  [001] The present invention represents a process for producing integrated semiconductor optoelectronic devices which relates to: (i) the use of transferred membranes as virtual substrates for the growth of epitaxial heterostructures on Si substrates; (ii) the production of semiconductor optoelectronic devices from the deposition of materials on thin films of compounds III-V after the transfer of thin films to Si substrates; (iii) the integration of semiconductor optoelectronic devices with Si substrates.
FUNDAMENTOS DA INVENÇÃO  BACKGROUND OF THE INVENTION
[002] Esta patente descreve um processo de fabricação de dispositivos semicondutores integrados constituídos por filmes finos. Para compreender o caráter inovador da invenção, é necessário familiarizar-se com os processos clássicos de fabricação de dispositivos integrados semicondutores e com os conceitos físicos nos quais se fundamentam.  [002] This patent describes a process for manufacturing integrated thin film semiconductor devices. To understand the innovative character of the invention, one needs to be familiar with the classical manufacturing processes of integrated semiconductor devices and the physical concepts on which they are based.
[003] A história dos semicondutores é longa e complexa. De acordo com tukasiak et al . , o termo "semicondutor" foi utilizado pela primeira vez por Alessandro Volta em 1782. A primeira observação documentada de um efeito semicondutor é creditada a Michael Faraday, que em 1833 observou que a resistência do sulfeto de prata (Ag2S) diminui com um aumento de temperatura, diferentemente do que é observado em metais.  [003] The history of semiconductors is long and complex. According to tukasiak et al. , the term "semiconductor" was first used by Alessandro Volta in 1782. The first documented observation of a semiconductor effect is credited to Michael Faraday, who in 1833 noted that silver sulfide (Ag2S) resistance decreases with an increase of temperature, unlike what is observed in metals.
[004] Materiais semicondutores podem ter natureza intrínseca ou podem ser extrínsecos, modificados física ou quimicamente para apresentar propriedades eletrônicas intensificadas. Os dois processos mais usados para modificação das propriedades eletrônicas de um material semicondutor são: (i) a dopagem ou "doping", que ocorre pela adição de "impurezas", como In ou P, na estrutura cristalina de semicondutores intrínsecos, como Si e Ge; ou (ii) a junção ou "junction", que é a modificação de propriedades pela união de diferentes materiais . Semiconductor materials may be intrinsic in nature or may be extrinsic, physically or chemically modified to exhibit enhanced electronic properties. The two most commonly used processes for modifying the electronic properties of a semiconductor material are: (i) doping, which occurs by the addition of "impurities" such as In or P to the crystal structure of intrinsic semiconductors such as Si and Ge; or (ii) the junction or junction, which It is the modification of properties by joining different materials.
[005] Nos primórdios da construção de dispositivos semicondutores, a forma preferencial era a bulk, ou seja, quando a porcentagem de átomos na superfície do material é muito pequena em relação ao número total de átomos. A revisão bibliográfica de tukasiak et al . aponta os principais usos desse tipo de semicondutores, como transistores de junção p-n e transistores de efeito de campo. Moss et al . exemplifica processos de síntese de diversos materiais semicondutores do tipo bulk.  [005] In the early days of semiconductor device construction, the preferred form was bulk, ie when the percentage of atoms on the material surface is very small relative to the total number of atoms. The literature review by tukasiak et al. points to the main uses of this type of semiconductor, such as p-n junction transistors and field effect transistors. Moss et al. exemplifies synthesis processes of various bulk semiconductor materials.
[006] Atualmente, a grande maioria dos semicondutores é extrínseca e o estado da arte evoluiu para o uso de nanomateriais como substratos, mais especificamente filmes finos. Um filme fino refere-se a uma camada de material ligada a um substrato, na qual a largura e o comprimento são muito maiores que a espessura, que se encontra na faixa de nanômetros . Outra definição oportuna é a de nanomembrana, que designa um filme fino livre, ou seja, desprendido ou fracamente ligado a um substrato. De acordo com Rogers et al . , as origens do trabalho em filmes finos datam de aproximadamente trinta anos atrás, a partir da investigação de nanocristais a base de cádmio e fulerenos esféricos. Rogers e tukasiak mostram uma ampla perspectiva dos processos de fabricação e aplicações de filmes finos em dispositivos semicondutores.  Currently, the vast majority of semiconductors are extrinsic and the state of the art has evolved into the use of nanomaterials as substrates, specifically thin films. A thin film refers to a layer of material attached to a substrate in which the width and length are much greater than the thickness in the nanometer range. Another timely definition is nanomembrane, which designates a free thin film, that is, loosened or loosely attached to a substrate. According to Rogers et al. , the origins of thin film work date back approximately thirty years ago from the investigation of cadmium-based nanocrystals and spherical fullerenes. Rogers and tukasiak show a broad perspective of thin film manufacturing processes and applications in semiconductor devices.
[007] Korotcenkov aponta que nanomateriais apresentam características cruciais como larga fração de átomos de superfície, alta energia de superfície, confinamento espacial e número reduzido de imperfeições que os distinguem positivamente em comparação a materiais bulk. Assim sendo, dispositivos produzidos a partir de filmes finos ou nanomembranas apresentam quatro vantagens claras em relação a seus correspondentes em bulk: (i) utilizam menos material, o que diminui os gastos com matéria-prima; (ii) alguns substratos utilizados podem ser reaproveitados, o que possibilita uma economia adicional no custo de produção; (iii) o baixo peso dos dispositivos permite uma ampla variedade de aplicações industriais; e (iv) os dispositivos podem ser mecanicamente flexíveis quando as dimensões são pequenas o suficiente. [007] Korotcenkov points out that nanomaterials exhibit crucial characteristics such as large fraction of surface atoms, high surface energy, spatial confinement and reduced number of imperfections that distinguish them positively compared to bulk materials. Thus, devices made from thin films or nanomembranes have four clear advantages over their bulk counterparts: (i) use less material, which reduces raw material costs; (ii) some substrates used may be reused, which allows additional production cost; (iii) the low weight of the devices allows for a wide variety of industrial applications; and (iv) the devices may be mechanically flexible when the dimensions are small enough.
[008] Como afirma Martini et al . , um dos processos amplamente conhecidos e usados no estado da técnica para produção de dispositivos a partir de filmes finos é o processo de deposição de monocamadas atómicas em substratos, denominado Epitaxia por Feixe Molecular (do inglês Molecular Beam Epitaxy ou MBE) . 0 termo epitaxia deriva da palavra grega epitaxis {epi = sobre, taxis = arranjo) que designa o crescimento sobre um substrato de um cristal que segue a mesma estrutura cristalina do substrato. 0 capítulo 3 de Callister et al. oferece uma sólida revisão sobre os conceitos fundamentais dessas estruturas cristalinas.  As stated by Martini et al. , one of the widely known processes used in the art for producing thin film devices is the process of depositing atomic monolayers on substrates called Molecular Beam Epitaxy (MBE). The term epitaxy is derived from the Greek word epitaxis (epi = over, taxis = arrangement) which designates growth on a crystal substrate that follows the same crystal structure as the substrate. Chapter 3 of Callister et al. offers a solid review of the fundamental concepts of these crystal structures.
[009] 0 MBE é uma técnica de crescimento de cristais a partir da evaporação de elementos químicos em um ambiente de ultra-alto vácuo (¾ 10~10 Torr) que assegura a integridade dos feixes incidentes durante o crescimento e limita os níveis de impurezas não intencionais que eventualmente possam ser incorporadas nas amostras. A técnica MBE é capaz de produzir camadas monocristalinas sobre substratos com precisão atómica, permitindo a confecção de nanoestruturas semicondutoras capazes de atender as crescentes demandas tecnológicas dos atuais dispositivos optoeletrônicos de emissão e absorção. Exemplos comerciais de tais dispositivos incluem células solares, LEDs e lasers . [009] 0 MBE is a crystal growth technique from the evaporation of chemicals in an ultra high vacuum (¾ 10 ~ 10 Torr) environment that ensures the integrity of incident beams during growth and limits impurity levels. that may be incorporated into the samples. The MBE technique is capable of producing monocrystalline layers on atomic precision substrates, allowing the fabrication of semiconductor nanostructures capable of meeting the growing technological demands of current optoelectronic emission and absorption devices. Commercial examples of such devices include solar cells, LEDs and lasers.
[0010] Como descrito na patente US 5,527,766, o material constituinte do substrato precisa ser compatível com os elementos constituintes dos filmes que serão depositados sobre o mesmo, entre outras restrições. A escolha do melhor substrato para um determinado dispositivo depende da sua aplicação final, da velocidade de crescimento do(s) filme (s) e da necessidade de um dispositivo da mais alta qualidade com a menor quantidade de defeitos mecânicos ou estruturais. [0011] Embora estas sejam as considerações principais na escolha do substrato, o estado da técnica mostra que outros fatores também devem ser avaliados para tomada de decisão. As described in US 5,527,766, the substrate constituent material must be compatible with the constituent elements of the films to be deposited thereon, among other restrictions. The choice of the best substrate for a given device depends on its final application, the growth rate of the film (s) and the need for the highest quality device with the least amount of mechanical or structural defects. Although these are the main considerations in choosing the substrate, the state of the art shows that other factors must also be evaluated for decision making.
[0012] 0 custo do substrato é um fator restritivo, mas não determinante para seleção de materiais precursores. Em geral, são usados substratos monocristalinos de alta pureza que tendem a ser muito caros, com exceção do uso de materiais abundantes e de ampla disponibilidade como o silício. Materiais policristalinos possuem menor custo, mas não são utilizados como substratos para processos de epitaxia.  [0012] Substrate cost is a restrictive but non-determining factor for selection of precursor materials. In general, high purity monocrystalline substrates are used which tend to be very expensive except for the use of abundant and widely available materials such as silicon. Polycrystalline materials have lower cost, but are not used as substrates for epitaxy processes.
[0013] 0 substrato deve também apresentar boa estabilidade térmica, porque o processamento dos cristais muitas vezes ocorre em altas temperaturas, que podem atingir até 900°C; portanto o substrato deve permanecer estável ao longo de toda a faixa de temperatura ao longo do processamento.  The substrate must also exhibit good thermal stability, because crystal processing often occurs at high temperatures, which may reach up to 900 ° C; therefore the substrate must remain stable over the entire temperature range throughout processing.
[0014] As propriedades de expansão térmica do substrato e do filme fino devem ser compatíveis, pois o processamento de cristais em altas temperaturas requer que o substrato e o filme se expandam e se contraiam de modo similar, evitando a quebra do cristal após o resfriamento.  The thermal expansion properties of the substrate and thin film should be compatible as high temperature crystal processing requires the substrate and film to expand and contract in a similar manner, preventing crystal breakage after cooling. .
[0015] A fragilidade dos substratos deve ser considerada, porque uma função importante do substrato é dar apoio ao filme fino. Se o próprio substrato é frágil, a estrutura global pode ter um nível inaceitavelmente elevado de fragilidade, comprometendo sua aplicação.  Substrate brittleness should be considered, because an important function of the substrate is to support the thin film. If the substrate itself is fragile, the overall structure may have an unacceptably high level of fragility, compromising its application.
[0016] A interdifusão entre o substrato e a película do filme fino deve ser a menor possível para que não haja defeitos e mudanças de propriedades elétricas e ópticas nas regiões de interface, o que pode ser revisado em detalhe no capítulo 5 de Callister et al .  The interdiffusion between the substrate and the thin film film should be as small as possible so that there are no defects and changes in electrical and optical properties in the interface regions, which can be reviewed in detail in Chapter 5 of Callister et al. .
[0017] A constante dielétrica do substrato deve ser escolhida cuidadosamente em função da aplicação final do dispositivo. Substratos aceitáveis pelas razões acima descritas, se apresentarem uma constante dielétrica muito elevada, podem ser inadequados para aplicações envolvendo efeitos dielétricos, como micro-ondas, pois a constante dielétrica do substrato afetará fortemente a constante dielétrica global do dispositivo semicondutor produzido. The dielectric constant of the substrate must be chosen carefully according to the final application of the device. Acceptable substrates for the reasons described above, if they have a very high dielectric constant, may be unsuitable for applications involving dielectric effects, microwaves, as the substrate dielectric constant will strongly affect the overall dielectric constant of the semiconductor device produced.
[0018] As possibilidades de formação de diferentes estruturas cristalinas no substrato precisam ser avaliadas em função do efeito das variáveis de temperatura e pressão sobre o substrato. Um fenómeno particularmente problemático decorrente deste efeito é a alotropia, onde ocorre mudança de estrutura cristalina que pode acarretar a formação de defeitos irreversíveis, inutilizando o dispositivo.  The possibilities of formation of different crystal structures in the substrate need to be evaluated as a function of the effect of temperature and pressure variables on the substrate. A particularly problematic phenomenon resulting from this effect is allotropy, where there is a change in crystal structure that can lead to the formation of irreversible defects, rendering the device unusable.
[0019] Em paralelo aos efeitos acima citados, também deve haver uma boa correspondência da estrutura cristalina entre o substrato e o filme e da formação das suas redes. Se os materiais não possuem um mesmo parâmetro de rede, um átomo dificilmente crescerá em cima do outro, gerando tensão ou relaxamento indesejado no filme. Antes da escolha da camada epitaxial, em geral determina-se a incompatibilidade entre as redes, dada por δ = (aepi - aSub)/aSub, onde aepi e aSUb correspondem respectivamente aos parâmetros de rede da camada epitaxial e do substrato. De acordo com Parker, no caso de filmes compostos por materiais do tipo III-V (B, Al, Ga, In, Tl, N, P, As, Sb, Bi) , os valores máximos de incompatibilidade de rede dependem da espessura do filme e dos materiais utilizados. In parallel to the effects mentioned above, there should also be a good correspondence of the crystal structure between the substrate and the film and the formation of their networks. If materials do not have the same network parameter, one atom will hardly grow on top of another, generating unwanted tension or relaxation in the film. Before choosing the epitaxial layer, the incompatibility between the networks is generally determined, given by δ = (a and pi - a S ub) / a S ub, where a and pi and SU b correspond respectively to the network parameters. epitaxial layer and substrate. According to Parker, in the case of films composed of type III-V materials (B, Al, Ga, In, Tl, N, P, As, Sb, Bi), the maximum net incompatibility values depend on the thickness of the film and materials used.
[0020] O material precursor mais comum em semicondutores é o silício. Substratos de Si são abundantes, baratos e fáceis de produzir. No entanto, estes substratos possuem um gap de energia indireto e baixa mobilidade dos portadores de carga. Além disso, substratos de Si são incompatíveis com muitas redes, incluindo os compostos III-V, representando obstáculos para a fabricação de dispositivos ópticos de baixo custo com alto desempenho.  The most common precursor material in semiconductors is silicon. Si substrates are plentiful, cheap and easy to produce. However, these substrates have an indirect energy gap and low load carrier mobility. In addition, Si substrates are incompatible with many networks, including III-V compounds, representing obstacles to the manufacture of low-cost, high-performance optical devices.
[0021] Várias tentativas foram feitas por pesquisadores nas últimas três décadas para sobrepujar o problema de substratos e filmes que não são perfeitamente compatíveis entre si, que resultaram em dois processos preferenciais para construção de dispositivos: (i) crescimento direto e (ii) pós-transferência do dispositivo. Several attempts have been made by researchers over the past three decades to overcome the problem of substrates and films that are not perfectly compatible with each other, which have resulted in two preferred device building processes: (i) direct growth and (ii) powders -transfer of the device.
[0022] 0 crescimento direto de um filme fino sobre um substrato pode ser observado na representação esquemática da Figura 1, exemplificando o estado da arte. Este processo é altamente complexo quando se trata do crescimento de elementos do grupo III-V em substratos de Si. No atual estado da arte, apesar de anos de pesquisa de diferentes autores, ainda não é possível obter dispositivos construídos por este processo com desempenho significativo. Os maiores problemas enfrentados são a incompatibilidade entre as redes e diferenças nos coeficientes de expansão térmica dos materiais, que geram dispositivos de qualidade abaixo da desejada.  The direct growth of a thin film on a substrate can be observed in the schematic representation of Figure 1, exemplifying the state of the art. This process is highly complex when it comes to the growth of group III-V elements in Si substrates. In the current state of the art, despite years of research by different authors, it is not yet possible to obtain devices constructed by this process with significant performance. . The major problems faced are the incompatibility between the networks and differences in the thermal expansion coefficients of the materials, which generate devices below the desired quality.
[0023] Uma alternativa empregada para atenuar esta dificuldade utiliza camadas buffer. Uma camada buffer é uma camada intermediária disposta entre o substrato e o filme desejado. Desde que sejam adequadamente escolhidas, camadas buffer são vantajosas porque tendem a impedir a interdifusão entre o substrato e o filme e nivelam a incompatibilidade das redes. Porém, a decisão de uso de camadas buffer deve ser cuidadosamente avaliada porque elas podem solucionar problemas de tensão/relaxamento dos filmes, mas simultaneamente podem criar problemas de dilatação térmica, aumentar custos de produção e elevar a constante dielétrica do dispositivo. Além disso, camadas buffer são soluções muito específicas que se adequam a uma particular combinação substrato/filme, não se constituindo em uma solução global. A patente US 7,202,503 descreve um exemplo de uso de camada buffer nas condições de crescimento direto de filme fino, fazendo uma transição de Si para Ge, ou seja, usando uma camada intermediária de um composto III-V ou II-VI que possui um parâmetro de rede intermediário entre o substrato de Si e o filme de Ge. Já a patente US 7,214,598 apresenta um processo no qual entre o substrato de Si e o filme de SiGe utiliza-se uma camada buffer de SiGe que possui uma concentração crescente de Ge, variando linearmente de 0% (próximo ao substrato de Si) a 50% (próximo ao filme de SiGe) . [0024] Um segundo processo, ilustrado na representação esquemática da Figura 2, consiste na transferência do dispositivo pronto para um novo substrato após seu crescimento sobre uma camada de sacrifício, removida pela técnica de epitaxial lift-off (ELO) , conhecida do estado da arte, como mostra Demeester et al. Em um processo convencional de ELO de compostos III-V, uma camada (normalmente de AlAs) é inserida entre o substrato e o filme. A estrutura resultante é então sujeita ao wet etching por uma solução de HF. 0 etching é um processo conhecido no estado da técnica e pode ser revisado nos artigos de Kelly et al., Voncken et al. e Donnelly et al. Após o etching, as camadas do dispositivo semicondutor são liberadas do substrato e transferidas para um novo. Na patente US 8, 435, 816, Xiong et al . apresentam um processo para a fabricação de um LED de InGaAlN. Nesta patente, uma mistura de HF e CH3COOH é utilizada para remover a camada de sacrifício de Si. Na patente US 8, 378, 385, Forrest et al . descrevem um processo de produção de dispositivos fotovoltaicos flexíveis utilizando ELO. An alternative employed to alleviate this difficulty utilizes buffer layers. A buffer layer is an intermediate layer arranged between the substrate and the desired film. Provided they are properly chosen, buffer layers are advantageous because they tend to prevent interdiffusion between the substrate and the film and even out the incompatibility of the networks. However, the decision to use buffer layers must be carefully evaluated because they can solve film tension / relaxation problems, but simultaneously can create thermal expansion problems, increase production costs and increase the dielectric constant of the device. In addition, buffer layers are very specific solutions that suit a particular substrate / film combination and are not a global solution. US 7,202,503 describes an example of using a buffer layer under direct thin-film growth conditions, making a transition from Si to Ge, that is, using an intermediate layer of a compound III-V or II-VI having a parameter intermediate network between Si substrate and Ge film. US 7,214,598 discloses a process in which between the Si substrate and the SiGe film a SiGe buffer layer is used which has an increasing concentration of Ge ranging linearly from 0% (near the Si substrate) to 50%. % (next to SiGe movie). A second process, illustrated in the schematic representation of Figure 2, is the transfer of the ready device to a new substrate after its growth on a sacrificial layer, removed by the known epitaxial lift-off (ELO) technique. art, as shown by Demeester et al. In a conventional ELO compound III-V process, a layer (usually AlAs) is inserted between the substrate and the film. The resulting structure is then wet etched by an HF solution. Etching is a known process in the art and can be reviewed in the articles by Kelly et al., Voncken et al. and Donnelly et al. After etching, the semiconductor device layers are released from the substrate and transferred to a new one. In US patent 4,435,816, Xiong et al. present a process for manufacturing an InGaAlN LED. In this patent, a mixture of HF and CH 3 COOH is used to remove the sacrificial layer of Si. In US patent 8,378,385, Forrest et al. describe a process of producing flexible photovoltaic devices using ELO.
[0025] Devido à complexidade do processo de crescimento direto, os recentes pesquisadores atuando na técnica vêm preferindo construir dispositivos usando o processo de pós- transferência .  Due to the complexity of the direct growth process, recent researchers working in the art have preferred to build devices using the post-transfer process.
[ 0026 ] Conforme citado por Soref, o dispositivo produzido pelo processo de pós-transferência teria desempenho e funcionalidade superiores do que os circuitos ópticos e elétricos tomados separadamente, porém este processo possui problemas intrínsecos ligados à integrabilidade dos dispositivos, ou seja, não permite a integração da óptica e da eletrônica em um mesmo substrato, especialmente com substratos de Si. As propriedades físicas do Si, como seu gap indireto de energia e baixa mobilidade dos portadores de carga, representam obstáculos para a produção bem-sucedida de dispositivos fotônicos com este processo.  As mentioned by Soref, the device produced by the post-transfer process would have superior performance and functionality than the optical and electrical circuits taken separately, but this process has intrinsic problems linked to the integrability of the devices, ie it does not allow integration of optics and electronics into the same substrate, especially with Si substrates. The physical properties of Si, such as its indirect energy gap and low load carrier mobility, represent obstacles to the successful production of photonic devices with this substrate. process.
[0027] No entanto, comparativamente ao processo de pós- transferência, o desenvolvimento de modificações tecnológicas adequadas no processo de crescimento direto permitiria essa integração, tendo sido essa, portanto, a base para geração da nova tecnologia apresentada neste pedido de invenção. However, compared to the post-transfer process, the development of technological modifications In the direct growth process, such integration would be the basis for generating the new technology presented in this application.
[0028] A presente invenção propõe uma solução inovadora para contornar os problemas de integração, compatibilidade e velocidade de crescimento acima apresentados para substratos de Si, por meio do uso de um filme fino transferido, denominado substrato virtual, que possibilita a fabricação de modo mais eficiente de uma série de dispositivos de alta qualidade integrados a substratos de Si.  [0028] The present invention proposes an innovative solution to circumvent the above integration, compatibility and growth rate problems for Si substrates by using a transferred thin film, called virtual substrate, which makes it possible to manufacture more efficiently. a range of high quality devices integrated with Si substrates.
[0029] 0 presente processo sugerido permite vantajosamente a fabricação de um substrato pronto para o crescimento epitaxial de diversos dispositivos via técnica de crescimento direto, suprimindo problemas de incompatibilidade de rede ou de expansão térmica.  [0029] The present suggested process advantageously allows the manufacture of a substrate ready for epitaxial growth of various devices via direct growth technique, suppressing network incompatibility or thermal expansion problems.
[0030] O presente processo considera a transferência de uma nanomembrana para o substrato de Si e a deposição de heteroestruturas de compostos III-V sobre o substrato virtual, assim evitando as desvantagens apresentadas pelo crescimento direto de materiais III-V sobre os substratos bulk, causadas comumente pela diferença entre seus parâmetros de rede. O crescimento direto do dispositivo sobre este substrato virtual evita a desvantagem da transferência do dispositivo pronto após seu crescimento, principalmente sua degeneração durante o processo epitaxial lift-off.  The present process considers the transfer of a nanomembrane to the Si substrate and the deposition of heterostructures of III-V compounds on the virtual substrate, thus avoiding the disadvantages presented by the direct growth of III-V materials on bulk substrates. commonly caused by the difference between your network parameters. The direct device growth on this virtual substrate avoids the disadvantage of ready device transfer after its growth, especially its degeneration during the lift-off epitaxial process.
[0031] As camadas transferidas podem ser eletricamente contatadas com o substrato, por exemplo, devido à interdifusão da camada de metal, como usado na tecnologia convencional de semicondutores, antes ou após o crescimento do dispositivo.  Transferred layers may be electrically contacted with the substrate, for example, due to the interdiffusion of the metal layer, as used in conventional semiconductor technology, before or after device growth.
[0032] A aptidão de camadas transferidas para o crescimento heteroepitaxial foi demonstrada por Sookchoo et al . apenas para o grupo IV de semicondutores, que inclui Si e Ge.  The suitability of transferred layers for heteroepitaxial growth has been demonstrated by Sookchoo et al. for semiconductor group IV only, which includes Si and Ge.
[0033] Durante a transferência, o substrato virtual pode ser posicionado sobre o novo substrato de modo a permitir sua integração aos circuitos semicondutores já previamente definidos no novo substrato. During the transfer, the virtual substrate can be positioned on the new substrate to allow its integration with the previously defined semiconductor circuits. on the new substrate.
BREVE DESCRIÇÃO DA INVENÇÃO  BRIEF DESCRIPTION OF THE INVENTION
[0034] A presente invenção representa um novo processo para o crescimento de heteroestruturas III-V epitaxiais sobre nanomembranas transferidas para substratos de Si, visando à fabricação de dispositivos optoeletrônicos de alta qualidade, tais como LEDs e lasers. Realizando-se o crescimento de heteroestruturas a partir de filmes finos transferidos, eliminam-se os problemas enfrentados pelos processos convencionais do processamento de semicondutores encontrados no estado da arte.  The present invention represents a novel process for the growth of epitaxial III-V heterostructures on nanomembranes transferred to Si substrates for the manufacture of high quality optoelectronic devices such as LEDs and lasers. By growing heterostructures from transferred thin films, the problems faced by conventional semiconductor processing processes found in the state of the art are eliminated.
[0035] A base do processo consiste na deposição de uma camada de sacrifício e de um filme fino de material III-V sobre um substrato apropriado, a partir de qualquer técnica de deposição epitaxial conhecida no estado da arte. Por exemplo, uma técnica aplicável é a Epitaxia por feixe molecular ou Molecular Beam Epitaxy (MBE) . Após a definição dos padrões na heteroestrutura pela técnica de fotolitografia, remove-sea camada de sacrifício por meio de wet etching e transfere-se o filme fino livre para um novo substrato, preferencialmente de Si, e realiza-se sua integração eletrônica ao mesmo. O filme fino agora atua como um substrato virtual e o conjunto formado pelo filme fino e o substrato de Si é apropriado ao crescimento direto de diversos dispositivos optoeletrônicos por processos já conhecidos e aplicados no estado da técnica.  The basis of the process is the deposition of a sacrificial layer and a thin film of material III-V on an appropriate substrate from any known epitaxial deposition technique. For example, an applicable technique is Molecular Beam Epitaxy or Molecular Beam Epitaxy (MBE). After the definition of the patterns in the heterostructure by the photolithography technique, the sacrificial layer is removed by wet etching and the free thin film is transferred to a new substrate, preferably Si, and electronically integrated to it. The thin film now acts as a virtual substrate and the thin film and Si substrate assembly is suitable for direct growth of various optoelectronic devices by known processes and applied in the state of the art.
[0036] Uma das formas típicas de uso desta invenção é no crescimento da estrutura de lasers de cavidade vertical e emissão superficial (VCSEL) , destinados para comunicação óptica, sistemas de TV de alta resolução, controle e sensoriamento de grandezas físicas e químicas, aplicações médicas e componentes automotivos .  One of the typical uses of this invention is in the growth of the structure of vertical cavity and surface emission lasers (VCSEL), intended for optical communication, high resolution TV systems, control and sensing of physical and chemical quantities, applications. medical and automotive components.
BREVE DESCRIÇÃO DAS FIGURAS  BRIEF DESCRIPTION OF THE FIGURES
[0037] A presente invenção será, a seguir, mais detalhadamente descrita com base em um exemplo de execução representado nos desenhos. As figuras mostram: [0038] A figura 1 é uma representação esquemática do processo de crescimento direto de dispositivos semicondutores do estado da arte. The present invention will hereinafter be described in more detail based on an exemplary embodiment shown in the drawings. The figures show: [0038] Figure 1 is a schematic representation of the direct growth process of state of the art semiconductor devices.
[0039] A figura 2 é uma representação esquemática do processo de crescimento e pós-transferência de dispositivos semicondutores do estado da arte.  [0039] Figure 2 is a schematic representation of the growth and post-transfer process of state of the art semiconductor devices.
[0040] A figura 3 é uma representação esquemática do processo de crescimento e transferência de filmes finos semicondutores, objeto da presente invenção.  [0040] Figure 3 is a schematic representation of the growth and transfer process of semiconductor thin films, object of the present invention.
[0041] A figura 4 é uma serie de imagens de microscopia óptica das etapas do processo de transferência de filmes finos semicondutores, objeto da presente invenção.  [0041] Figure 4 is a series of optical microscopy images of the steps of the semiconductor thin film transfer process, object of the present invention.
[0042] A figura 5 é uma microscopia de força atómica do substrato virtual do processo de crescimento de dispositivos semicondutores, objeto da presente invenção.  Figure 5 is an atomic force microscopy of the virtual substrate of the semiconductor device growth process, object of the present invention.
DESCRIÇÃO DETALHADA DAS FIGURAS  DETAILED DESCRIPTION OF THE FIGURES
[0043] As Figuras 1, 2 e 3 a seguir não estão representadas em escala. As Figuras 4 e 5 possuem escalas representadas em suas correspondentes imagens.  The following Figures 1, 2 and 3 are not shown to scale. Figures 4 and 5 have scales represented in their corresponding images.
[0044] A Figura 1 representa o processo de crescimento direto de dispositivos semicondutores sobre substratos. O substrato bulk (1) pode ser escolhido de um grupo apropriado de materiais semicondutores que inclui Si, GaAs, InP e outros. Observa-se a etapa de deposição direta (2) do dispositivo sobre o substrato, podendo ser escolhido entre um grupo de técnicas conhecidas e aplicadas no estado da técnica que inclui epitaxia por feixe molecular (MBE) , deposição química em fase de vapor, pulverização catódica ou sputtering, entre outras. O dispositivo optoeletrônico pronto (3) tem aplicação como diodo, transistor ou laser.  Figure 1 depicts the direct growth process of semiconductor devices on substrates. Bulk substrate (1) may be chosen from an appropriate group of semiconductor materials including Si, GaAs, InP and others. The direct deposition step (2) of the device is observed on the substrate and can be chosen from a group of known and state-of-the-art techniques including molecular beam epitaxy (MBE), chemical vapor deposition, spraying. cathodic or sputtering, among others. The ready optoelectronic device (3) has application as diode, transistor or laser.
[0045] A Figura 2 representa o processo de crescimento e pós-transferência de dispositivos semicondutores sobre substratos por epitaxial lift-off. O substrato bulk (1) recebe uma camada de sacrifício (4) que é constituída por materiais como AlAs, Si, SÍO2, GaAs, entre outros semicondutores. A seguir, diversas camadas do dispositivo são depositadas progressivamente sobre a camada de sacrifício (4) usando técnicas do grupo que inclui MBE, deposição química em fase de vapor, sputtering, entre outras, formando a heteroestrutura (5) . 0 dispositivo optoeletronico pronto (3) é obtido pela remoção da camada sacrificial (4) por técnicas conhecidas do estado da arte como wet-etching ou plasma etching e sua pós-transferência a um novo substrato . Figure 2 depicts the growth and post-transfer process of semiconductor devices on epitaxial lift-off substrates. The bulk substrate (1) receives a sacrificial layer (4) which consists of materials such as AlAs, Si, SiO2, GaAs, among other semiconductors. Next, Several layers of the device are progressively deposited on the sacrificial layer (4) using techniques from the group including MBE, vapor phase chemical deposition, sputtering, among others, forming the heterostructure (5). The ready optoelectronic device (3) is obtained by removing the sacrificial layer (4) by known state of the art techniques such as wet etching or plasma etching and its post-transfer to a new substrate.
[0046] A Figura 3 demonstra o processo introduzido pela presente invenção. Em uma modalidade preferida, deposita-se uma camada de sacrifício (4) de AlAs sobre um substrato bulk (1) monocristalino de GaAs a uma temperatura entre 4002C e 650°C. A seguir, é realizada sobre a camada de sacrifício (4) uma deposição epitaxial (2), usando técnicas do grupo que inclui MBE, deposição química em fase de vapor, sputtering, entre outras, de elementos semicondutores, que se incorporam sobre a camada de sacrifício (4) e formam um filme fino (6) . 0 filme fino (6) possui espessura menor do que 20 nm e se constitui de elementos III-V ou suas combinações em ligas de diferentes composições, preferencialmente InxGai-xAs, InxGai-xAlAs, InGaAlP ou InGaAlN. A camada de sacrifício (4) é então removida por uma das técnicas de etching conhecidas no estado da arte e o filme fino liberado, ora denominado nanomembrana (8) , é transferido para um novo substrato bulk (7) , selecionado entre um grupo apropriado de materiais semicondutores, preferencialmente Si. Após limpeza por uma das técnicas conhecidas no estado da arte, obtém-se uma estrutura adequada para o crescimento epitaxial formada pela nanomembrana (8) transferida, denominada substrato virtual (9), e o novo substrato (7) de Si. Esse conjunto (10), formado pelo novo substrato bulk (7) mais o substrato virtualtransferido (9), poderá ser usado como base para o crescimento direto de qualquer dispositivo optoeletronico usual por técnicas conhecidas de processamento de semicondutores. Figure 3 demonstrates the process introduced by the present invention. In a preferred embodiment, is deposited a sacrificial layer (4) of AlAs on a bulk substrate (1) of monocrystalline GaAs at a temperature between 400 C and 2 650 ° C. Next, an epitaxial deposition (2) is performed on the sacrificial layer (4) using techniques from the group including MBE, chemical vapor phase deposition, sputtering, among others, of semiconductor elements, which are incorporated into the layer. (4) and form a thin film (6). 0 thin film (6) has a thickness less than 20 nm and is composed of III-V elements or combinations of alloys of different compositions, preferably Gai- x In x As, In x x Gai- AlAs, InGaAlP or InGaAlN. The sacrificial layer (4) is then removed by one of the state-of-the-art etching techniques and the released thin film, sometimes called nanomembrane (8), is transferred to a new bulk substrate (7) selected from an appropriate group. semiconductor materials, preferably Si. After cleaning by one of the known techniques in the art, a suitable structure for epitaxial growth formed by the transferred nanomembrane (8), called virtual substrate (9), and the new substrate (7) is obtained. ) Si. This assembly (10), formed by the new bulk substrate (7) plus the transferred virtual substrate (9), can be used as the basis for the direct growth of any usual optoelectronic device by known semiconductor processing techniques.
[0047] O processo pode ser desmembrado em passos que combinam aspectos das técnicas de epitaxial lift-off e de crescimento direto . The process can be broken down into steps that combine aspects of lift-off epitaxial and growth techniques. straightforward.
[0048] Sobre o substrato bulk (1) , é crescida uma camada de sacrifício (4) com espessura podendo variar entre 4 nm e 2000 nm, de modo a permitir a posterior retirada (lift-off) e transferência das camadas para o novo substrato (7) . Sobre a camada de sacrifício (4), é crescido um filme fino (6) de compostos III-V, que compreendem B, Al, Ga, In, Tl, N, P, As, Sb, Bi e incluindo suas ligas metálicas e não-metálicas . À espessura da camada superior é imposta a condição de ser mais fina do que a espessura crítica a partir da qual se inicia a formação de defeitos no sistema epitaxial escolhido.  On the bulk substrate (1), a sacrificial layer (4) with a thickness ranging from 4 nm to 2000 nm is grown so as to allow later lift-off and transfer of the layers to the new one. substrate (7). On the sacrificial layer (4) is grown a thin film (6) of compounds III-V comprising B, Al, Ga, In, T1, N, P, As, Sb, Bi and including their alloys and non-metallic. The thickness of the upper layer is imposed on the condition that it is thinner than the critical thickness from which the formation of defects in the chosen epitaxial system begins.
[0049] Uma forma típica da invenção consiste no depósito de um filme fino de espessura entre 2 e 100 nm, preferencialmente de 10 nm, composto de Ino.33Gao.67As, crescido sobre uma camada de sacrifício de AlAs a uma temperatura entre 400 e 6502C. A typical form of the invention is the deposition of a thin film of between 2 and 100 nm, preferably 10 nm, composed of Ino.33Gao.67As, grown on an AlAs sacrificial layer at a temperature between 400 and 400 ° C. 650 2 C.
[0050] O filme fino (6) é liberado do substrato bulk original (1) pela remoção seletiva da camada de sacrifício (4) . Durante a liberação, o filme fino (6) relaxa e seu parâmetro de rede iguala-se ao de sua forma bulk, que pode ser menor ou maior do que o parâmetro de rede do substrato bulk original (1) . O parâmetro de rede do novo conjunto (10) independe do novo substrato (7) e é definido exclusivamente pelas propriedades do filme fino, que passa a ser denominado nanomembrana (8) transferida .  The thin film (6) is released from the original bulk substrate (1) by selective removal of the sacrificial layer (4). During release, the thin film (6) relaxes and its mesh parameter equals that of its bulk shape, which may be smaller or larger than the mesh parameter of the original bulk substrate (1). The lattice parameter of the new set (10) is independent of the new substrate (7) and is defined exclusively by the properties of the thin film, which is now called the transferred nanomembrane (8).
[0051] Para o exemplo da camada de Ino.33Gao.67As supramencionada, o parâmetro de rede está entre 0, 583 nm e 0,601 nm, parâmetros de rede do GaAs e InAs, respectivamente. O processo de relaxamento dessa camada já foi estudado e demonstrado por Mei et al.  For the example of the aforementioned Ino.33Gao.67As layer, the network parameter is between 0. 583 nm and 0.601 nm, GaAs and InAs network parameters, respectively. The relaxation process of this layer has already been studied and demonstrated by Mei et al.
[0052] O filme fino (6) é então removido e transferido ao novo substrato (7) conforme Malachias et al . O novo substrato (7) deve ser apropriado para o crescimento direto e ter as propriedades complementares desejadas às da camada de filme fino, então denominado nanomembrana (8) transferida.  The thin film (6) is then removed and transferred to the new substrate (7) according to Malachias et al. The new substrate (7) should be suitable for direct growth and have the desired complementary properties to those of the thin film layer, then called nanomembrane (8) transferred.
[0053] Uma forma típica desta invenção usa o silício como novo substrato (7) , porque é um substrato barato, versátil e adequado para circuitos altamente integrados, sendo a base da tecnologia dos computadores modernos. 0 Si não é o substrato ótimo para construção de dispositivos optoeletrônicos devido ao seu gap de energia ser indireto, mas como citado neste documento, uma produção bem-sucedida de dispositivos ópticos integrados ao Si apresenta alto interesse. A transferência para outros substratos que não o Si já foi demonstrada por vários autores, incluindo os inventores desta invenção, como mostrado em Malaquias et al . A typical form of this invention uses silicon as new substrate (7), because it is a cheap, versatile substrate suitable for highly integrated circuits, and is the basis of modern computer technology. Si is not the optimal substrate for optoelectronic device construction because of its indirect energy gap, but as noted in this paper, successful production of Si-integrated optical devices is of high interest. Transfer to substrates other than Si has been demonstrated by several authors, including the inventors of this invention, as shown in Malaquias et al.
[ 0054 ] Durante ou após a transferência, a nanomembrana (8) é eletricamente conectada ao substrato usando um processo de difusão ou por ligação direta. Através de impressão em soft- imprint lithography, a camada é precisamente alinhada ao novo substrato (7), como demonstrado para o Si por Kim et al .  During or after transfer, the nanomembrane (8) is electrically connected to the substrate using a diffusion or direct bonding process. Through soft-imprint lithography printing, the layer is precisely aligned to the new substrate (7), as demonstrated for Si by Kim et al.
[0055] Após a transferência, a camada III-V, que passa a ser denominada substrato virtual estando no novo substrato (7), é limpa. A limpeza deve ser feita inicialmente para a remoção do fotorresiste e depois dos óxidos depositados na superfície da camada III-V. As substâncias de limpeza do fotorresiste incluem soluções de ácido sulfúrico, SemiconClean 23 (Furuuchi Chemical Corporation), dimetil sulfóxido e acetona. A etapa de limpeza inclui ainda o uso de hidrogénio atómico ou um tratamento térmico para remoção de óxidos. Deneke et al. descreve processos bem estabelecidos de limpeza para camadas em substratos bulk, que aqui são incorporadas por referência e aplicadas no substrato virtual para possibilitar o crescimento direto de dispositivos por epitaxia sobre o conjunto (10) .  After transfer, layer III-V, which is renamed virtual substrate being in the new substrate (7), is cleared. Cleaning should be done initially to remove the photoresist and then the oxides deposited on the surface of layer III-V. Photoresist cleaning substances include solutions of sulfuric acid, SemiconClean 23 (Furuuchi Chemical Corporation), dimethyl sulfoxide and acetone. The cleaning step further includes the use of atomic hydrogen or an oxide removal heat treatment. Deneke et al. describes well established bulk layer cleaning processes which are incorporated herein by reference and applied to the virtual substrate to enable direct growth of epitaxy devices onto the assembly (10).
[0056] Após a limpeza, a nanomembrana (8) transferida pode ser utilizada como substrato virtual para o crescimento epitaxial de compostos III-V. Este posterior processo de crescimento direto sobre o substrato virtual é possível de ser realizado e é corroborado por resultados de estudos ainda não publicados pelos inventores desta invenção.  Following cleaning, the transferred nanomembrane (8) can be used as a virtual substrate for epitaxial growth of compounds III-V. This further process of direct growth on the virtual substrate is possible and is corroborated by results of studies not yet published by the inventors of this invention.
[0057] O conjunto (10) pode ser constituído por diferentes composições de ligas de compostos III-V e ainda exibir parâmetro de rede diferente de substratos bulk comuns como GaAs ou InP . Por conseguinte, praticamente qualquer tipo de dispositivo óptico-eletrônico convencional pode ser crescido sobre o substrato por processos heteroepitaxiais . Possíveis dispositivos incluem os mencionados lasers de cavidade vertical (VCSEL) para telecomunicações, normalmente crescidos sobre InP ou transistores de alta mobilidade eletrônica (HEMT) para aplicações de eletrônica de alta velocidade. The set (10) may consist of different alloy compositions of compounds III-V and still exhibit different network parameter from common bulk substrates such as GaAs or InP. Accordingly, virtually any type of conventional optical-electronic device can be grown on the substrate by heteroepitaxial processes. Possible devices include the aforementioned telecommunications vertical cavity lasers (VCSEL), typically grown over InP, or high mobility electronic transistors (HEMT) for high speed electronics applications.
[0058] Após o crescimento, os dispositivos podem ser fabricados sobre a heteroestrutura crescida utilizando técnicas já bem estabelecidas de processamento industrial de semicondutores de grande área física que incluem litografia, gravura a íons reativos, implantação iônica, entre outras.  [0058] After growth, the devices can be fabricated over the grown heterostructure using well-established techniques for large-area industrial semiconductor processing that include lithography, reactive ion etching, ion implantation, and others.
[0059] A Figura 4 apresenta uma série de imagens de microscopia referentes as etapas de uma modalidade preferida do processo da presente invenção. Da esquerda para a direita, temos: padrões definidos no topo de uma heteroestrutura GaAs/AlAs/InxGai-xAs (11) ; a estrutura após o primeiro wet-etching que definiu as trincheiras ( 12 ) ; substrato após o epitaxial lift- off (13) ; substrato após a transferência da nanomembrana (14) ; nanomembranas no novo substrato de Si (15,16) . Figure 4 shows a series of microscopy images referring to the steps of a preferred embodiment of the process of the present invention. From left to right are: standards set atop a heterostructure GaAs / AlAs / In x x The Gai- (11); the structure after the first wet etching that defined the trenches (12); substrate after lift-off epitaxial (13); substrate after nanomembrane transfer (14); nanomembranes in the new Si substrate (15,16).
[0060] A Figura 5 apresenta uma imagem de microscopia de força atómica (AFM) da superfície de uma membrana de InGaAs preparada pela técnica de pós-crescimento apresentada na Figura Figure 5 shows an atomic force microscopy (AFM) image of the surface of an InGaAs membrane prepared by the post-growth technique shown in Figure
4, após sua liberação e limpeza. A alta qualidade da nanomembrana é confirmada pela baixa rugosidade do material, facilmente observável na imagem da figura 5 para aqueles versados no estado da arte. 4, after its release and cleaning. The high quality of the nanomembrane is confirmed by the low roughness of the material, easily observed in the image of figure 5 for those skilled in the state of the art.
EXEMPLO DO DISPOSITIVO INCLUINDO APLICAÇÕES  EXAMPLE OF DEVICE INCLUDING APPLICATIONS
[0061] O exemplo a seguir descreve passo a passo o processo quando empregado no crescimento da estrutura de um laser de cavidade vertical e emissão superficial (VCSEL) sobre um substrato (7) de Si recoberto por uma nanomebrana (8) de InGaAs. Esta forma de implantação da invenção é apenas ilustrativa e em nenhuma hipótese restringe o escopo da mesma. Os passos do processo em geral são semelhantes para qualquer outro tipo de heteroestrutura, com exceção do passo VIII que pode ser alterado em função da natureza da heteroestrutura que se deseja crescer no conjunto (10) . The following example describes the process step by step when employed in the growth of the structure of a vertical cavity and surface emission laser (VCSEL) on a Si substrate (7) covered by an InGaAs nanomebranch (8). This embodiment of the invention is illustrative only and in no hypothesis restricts its scope. The process steps are generally similar for any other type of heterostructure, except for step VIII which may be changed depending on the nature of the heterostructure that is to be grown in the set (10).
[0062] Passo I: Sobre um substrato bulk (1) comercial de GaAs (001) apropriado para crescimento epitaxial é crescida uma heteroestrutura de AlAs/InxGai-xAs utilizando-se epitaxia de feixe molecular (MBE) . Para tal fim, o substrato de GaAs é aquecido a 600 °C no equipamento de MBE para a remoção dos óxidos nativos. Uma camada buffer de GaAs com 200 nm de espessura é crescida sobre o substrato bulk (1) seguindo-se procedimentos padrões de crescimento por MBE. Após o crescimento da camada buffer, a temperatura do substrato é reduzida para 500°C e uma camada de sacrifício (4) de 20 nm de espessura de AlAs seguida por outra camada, denominada filme fino (6), de Ino,2Gao,sAs também com 20 nm (doravante denominada filme fino (6) de InGaAs) são depositadas sobre a camada buffer. [0062] Step I: About a bulk substrate (1) Commercial GaAs (001) suitable for epitaxial growth is grown heterostructure of one AlAs / x In x As Gai- using molecular beam epitaxy (MBE). To this end, the GaAs substrate is heated to 600 ° C in the MBE equipment for removal of native oxides. A 200 nm thick GaAs buffer layer is grown on the bulk substrate (1) following standard MBE growth procedures. After growth of the buffer layer, the substrate temperature is reduced to 500 ° C and a 20 nm AlAs sacrificial layer (4) followed by another layer, called Ino, 2Gao, sAs thin film (6). also at 20 nm (hereinafter referred to as InGaAs thin film (6)) are deposited on the buffer layer.
[0063] Passo II: A heteroestrutura é removida da câmara de MBE e realiza-se um processo de fotolitografia para se definir os padrões na heteroestrutura. Utilizam-se como padrões círculos de aproximadamente 150 um de diâmetro. Por wet-etching usando uma solução de H2O2 : H3PO : H2O (relação mássica 10:1:100) os padrões definidos pela fotolitografia são reproduzidos na heteroestrutura. Após o etching, o material fotossensível (fotorresiste) permanece na estrutura, sobre o filme fino (6) de InGaAs .  Step II: The heterostructure is removed from the MBE chamber and a photolithography process is performed to define the patterns in the heterostructure. Circles approximately 150 µm in diameter are used as standards. By wet etching using a H2O2: H3PO: H2O solution (10: 1: 100 mass ratio) the patterns defined by photolithography are reproduced in the heterostructure. After etching, the photosensitive material (photoresist) remains in the structure over the thin film (6) of InGaAs.
[0064] Passo III: O filme fino (6) de InGaAs é então liberado do substrato bulk (1) pela remoção seletiva da camada de sacrifício (4) de AlAs pelo processo de wet-etching. O AlAs é removido utilizando-se uma solução diluída de HF, conhecida pela alta seletividade {epitaxial lift-off) . Durante o lift-off, embora esteja ligado ao fotorresiste, o filme fino (6) de InGaAs é relaxado, uma vez que o fotorresiste é muito mais maleável do que o InGaAs. Durante a remoção da camada de sacrifício (4) AlAs, as nanomembranas (8) caem para o substrato de GaAs, sendo fracamente ligadas a este. Step III: InGaAs thin film (6) is then released from the bulk substrate (1) by selective removal of the AlAs sacrificial layer (4) by wet-etching. AlAs are removed using a dilute HF solution known for high selectivity (epitaxial lift-off). During lift-off, although attached to the photoresist, InGaAs thin film (6) is relaxed as the photoresist is much more malleable than InGaAs. During the removal of the sacrificial layer (4) AlAs, the nanomembranes (8) fall to the GaAs substrate and are weakly bound to it.
[0065] Passo IV: Utilizando uma técnica chamada soft-imprint lithography, a nanomembrana (8) é transferida para um substrato de transporte selecionado de um grupo de materiais que inclui vidro, silício e quaisquer materiais lisos e resistentes aos produtos usados nos passos V e VI . Inicialmente o substrato de transporte é revestido pelo fotorresiste . A seguir, pressiona- se a face revestida com o fotorresiste contra o substrato bulk (1) de GaAs e sua nanomembrana (8) liberada de InGaAs. 0 fotorresiste age como uma cola, unindo as membranas ao substrato intermediário. Esse processo está ilustrado nas Figuras 3 e 4, descritas em detalhes na seção Descrição Detalhada das Figuras.  Step IV: Using a technique called soft-imprint lithography, nanomembrane (8) is transferred to a transport substrate selected from a material group that includes glass, silicon and any smooth, product-resistant materials used in steps V and VI. Initially the transport substrate is coated by the photoresist. Next, the photoresist-coated face is pressed against the bulk substrate (1) of GaAs and its nanomembrane (8) released from InGaAs. The photoresist acts as a glue, binding the membranes to the intermediate substrate. This process is illustrated in Figures 3 and 4, described in detail in the Detailed Description of Figures section.
[0066] Passo V: Agora, a nanomembrana (8) de InGaAs (com resíduos do fotorresiste) no topo do substrato de transporte é pressionado e transferida a um novo substrato (7) , neste caso um wafer de Si (001) . Um tratamento térmico assegura a ligação da membrana (8) de InGaAs ao substrato de Si. O substrato de transporte é retirado após a remoção do fotorresiste, que é realizada utilizando-se um removedor convencional utilizado em fotolitografia, como DSMO ou acetona.  Step V: Now InGaAs nanomembrane (8) (with photoresist residues) on top of the transport substrate is pressed and transferred to a new substrate (7), in this case a Si wafer (001). A heat treatment ensures that InGaAs membrane (8) is bonded to the Si substrate. The transport substrate is removed after photoresist removal, which is performed using a conventional photolithography remover such as DSMO or acetone.
[0067] Passo VI: Para adequar o conjunto final (10), formado pelo substrato Si (7) mais a nanomembrana (8) transferida, ao crescimento epitaxial, a superfície deve ser quimicamente limpa. Um processo padrão, que não ataca o substrato subjacente de Si, é o wet etching em H2SO4 por 10 minutos, lavagem com água, etching por 2 minutos em SemiconClean 23 (Furuuchi Chemical Corporation) , lavagem com água por 10 minutos e secagem. O conjunto (10) agora está pronto para o crescimento epitaxial.  Step VI: To fit the final assembly (10) formed by the substrate Si (7) plus the transferred nanomembrane (8) to the epitaxial growth, the surface must be chemically cleaned. A standard process, which does not attack the underlying Si substrate, is wet etching in H2SO4 for 10 minutes, water washing, etching for 2 minutes in SemiconClean 23 (Furuuchi Chemical Corporation), water washing for 10 minutes and drying. Set 10 is now ready for epitaxial growth.
[0068] Passo VII: O conjunto (10) é reintroduzido no sistema para deposição por MBE . Antes de crescer a heteroestrutura, é realizada uma limpeza com hidrogénio atómico para remover o óxido nativo do InGaAs e demais impurezas. Heteroestruturas epitaxiais podem agora ser depositadas no topo do conjunto (10) , empregando-se os processos descritos na literatura. A Figura 5 mostra a alta qualidade da superfície da nanomembrana (8) após a limpeza e antes do crescimento. Step VII: Set (10) is reintroduced into the system for MBE deposition. Before the heterostructure is grown, an atomic hydrogen cleaning is performed to remove native oxide from InGaAs and other impurities. Epitaxial heterostructures can now be deposited on top of the assembly (10) using the methods described in the literature. Figure 5 shows the high quality of the nanomembrane surface (8) after cleaning and before growth.
[0069] Passo VIII: Crescer uma estrutura VCSEL sobre InGaAs requer algumas modificações em seus componentes usuais para que estes se adaptem ao parâmetro de rede da membrana relaxada de InGaAs, todavia todos os componentes da estrutura VCSEL podem ser crescidos sobre o substrato virtual (9) . As estruturas principais são: (a) embaixo, um espelho de Bragg de uma super- rede de InGaAs /InAlGaAs; (b) na cavidade ativa do laser, estrutura de InAlGaAs/InGaAs/ InAlGaAs e (c) no topo, um espelho de Bragg de uma super-rede de InGaAs / InAlGaAs . Neste processo, o VCSEL pode ser substituído por qualquer heteroestrutura, pois o substrato virtual comporta-se como um substrato adequado para o crescimento epitaxial.  Step VIII: Growing a VCSEL structure over InGaAs requires some modifications to its usual components to fit the InGaAs relaxed membrane network parameter, however all components of the VCSEL structure can be grown over the virtual substrate (9). ). The main structures are: (a) below, a Bragg mirror of an InGaAs / InAlGaAs superstructure; (b) in the active laser cavity, InAlGaAs / InGaAs / InAlGaAs structure and (c) at the top, a Bragg mirror from an InGaAs / InAlGaAs superstructure. In this process, VCSEL can be replaced by any heterostructure, as the virtual substrate behaves as a suitable substrate for epitaxial growth.
[0070] Passo IX: Após a deposição do material, um passo adicional é necessário para retirada do material depositado em áreas não cobertas pela nanomembrana transferida. Portanto, deve ser feito um segundo processo de litografia utilizando a máscara do primeiro processo. Como a posição da nanomembrana de InGaAs no substrato de Si é definida pelo padrão da primeira litografia, é necessário apenas o alinhamento correto entre a máscara e a nanomembrana de InGaAs. As áreas com material desejado podem ser cobertas pelo fotorresiste, de modo que o wet-etching remova apenas o material de áreas não cobertas pela membrana de InGaAs.  Step IX: After material deposition, an additional step is required for removal of the deposited material in areas not covered by the transferred nanomembrane. Therefore, a second lithography process should be done using the mask of the first process. Since the position of the InGaAs nanomembrane on the Si substrate is defined by the pattern of the first lithograph, only the correct alignment between the mask and the InGaAs nanomembrane is required. Areas with desired material can be photoresisted so that wet etching removes only material from areas not covered by the InGaAs membrane.
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Claims

REIVINDICAÇÕES
1. Processo para produção de dispositivos optoeletrônicos III-V integrados em silício, caracterizado por compreender as etapas de  1. Process for the production of silicon integrated III-V optoelectronic devices, characterized in that it comprises the steps of
crescimento de pelo menos uma camada de sacrifício (4) sobre um substrato bulk (1) ;  growing at least one sacrificial layer (4) on a bulk substrate (1);
deposição de pelo menos um filme fino (6) sobre a camada de sacrifício (4) ;  depositing at least one thin film (6) on the sacrificial layer (4);
remoção seletiva da pelo menos uma camada de sacrifício (4) ; remoção do pelo menos um filme fino (6) do substrato bulk selective removal of at least one sacrificial layer (4); removing at least one thin film (6) from bulk substrate
(1) , o filme fino livre passando a se denominar nanomembrana (8) ; (1), the free thin film is renamed nanomembrane (8);
transferência do pelo menos uma nanomembrana (8) para um novo substrato (7) ;  transferring at least one nanomembrane (8) to a new substrate (7);
limpeza da pelo menos uma nanomembrana (8) sobre o novo substrato (7), sendo a camada transferida denominada substrato virtual ( 9) ;  cleaning at least one nanomembrane (8) on the new substrate (7), the transferred layer being called virtual substrate (9);
crescimento direto de heteroestruturas semicondutoras sobre direct growth of semiconductor heterostructures over
0 conjunto (10) formado pelo o substrato virtual (9) e o novo substrato (7) . The assembly (10) formed by the virtual substrate (9) and the new substrate (7).
2. Processo, de acordo com a reivindicação 1, caracterizado pelo fato de que o substrato virtual (9) compreende pelo menos uma camada de membrana (8) transferida sobre o substrato bulk (7) .  Process according to Claim 1, characterized in that the virtual substrate (9) comprises at least one membrane layer (8) transferred over the bulk substrate (7).
3. Processo, de acordo com qualquer uma das reivindicações Process according to any one of the claims
1 ou 2, caracterizado pelos filmes finos (6) serem constituídos por uma combinação dos elementos do grupo III-V que compreendem B, Al, Ga, In, Tl, N, P, As, Sb, Bi e incluindo suas ligas metálicas e não-metálicas . 1 or 2, characterized in that the thin films (6) consist of a combination of elements of group III-V comprising B, Al, Ga, In, T1, N, P, As, Sb, Bi and including their metal alloys and non-metallic.
4. Processo, de acordo com a reivindicação 3, caracterizado pelo fato de que o filme fino (6) gerado pelos elementos do grupo III-V é semicondutor.  Process according to Claim 3, characterized in that the thin film (6) generated by the elements of group III-V is semiconductor.
5. Processo, de acordo com a reivindicação 4, caracterizado pelo fato de que os filmes finos (6) semicondutores são preferencialmente constituídos por uma liga de compostos III-V do grupo de gap de energia direto que compreende InGaAs, InGaAlAs, InGaAlP e InGaAlN. Process according to claim 4, characterized in that the semiconductor thin films (6) preferably consist of an alloy of compounds III-V of the direct energy gap group comprising InGaAs, InGaAlAs, InGaAlP and InGaAlN.
6. Processo, de acordo com qualquer uma das reivindicações 4 ou 5, caracterizado pelo filme fino (6) semicondutor ser formado pela deposição dos compostos III-V sobre uma camada de sacrifício (4) preparada sobre um substrato bulk (1) .  Process according to either of Claims 4 and 5, characterized in that the semiconductor thin film (6) is formed by the deposition of compounds III-V on a sacrificial layer (4) prepared on a bulk substrate (1).
7. Processo, de acordo com a reivindicação 6, caracterizado pelo fato de que o substrato bulk (1) é monocristalino .  Process according to Claim 6, characterized in that the bulk substrate (1) is monocrystalline.
8. Processo, de acordo com a reivindicação 7, caracterizado pelo fato de que o substrato bulk (1) monocristalino é preferencialmente escolhido de um grupo de materiais adequados para suportar o crescimento epitaxial das estruturas, como GaAs .  Process according to Claim 7, characterized in that the monocrystalline bulk (1) substrate is preferably chosen from a group of materials suitable to support epitaxial growth of structures such as GaAs.
9. Processo, de acordo com qualquer uma das reivindicações 7 ou 8, caracterizado pelo fato de que a camada de sacrifício (4) é constituída por um ou mais materiais escolhidos de um grupo de materiais compatíveis com o substrato bulk (1) monocristalino e com o filme fino (6) a ser depositado, como AlAs.  Process according to either claim 7 or claim 8, characterized in that the sacrificial layer (4) is comprised of one or more materials selected from a group of materials compatible with the monocrystalline bulk (1) substrate and with the thin film (6) to be deposited, such as AlAs.
10. Processo, de acordo com a reivindicação 9, caracterizado pelo fato de que a camada de sacrifício (4) é depositada sobre o substrato bulk (1) monocristalino através de uma técnica de deposição epitaxial, como epitaxia por feixe molecular (MBE) ou deposição química por fase de vapor.  Process according to Claim 9, characterized in that the sacrificial layer (4) is deposited on the monocrystalline bulk substrate (1) by an epitaxial deposition technique such as molecular beam epitaxy (MBE) or chemical vapor deposition.
11. Processo, de acordo com qualquer uma das reivindicações 7, 8, 9 ou 10, caracterizado pelo fato de que a camada de sacrifício (4) é depositada sobre o substrato bulk (1) monocristalino a uma temperatura entre 4002C e 650 °C. 11. Process according to any one of claims 7, 8, 9 or 10, characterized in that the sacrificial layer (4) is deposited on the bulk substrate (1) single crystal at a temperature between 400 C and 650 2 ° C.
12. Processo, de acordo com qualquer uma das reivindicações 7, 8, 9, 10 ou 11, caracterizado pelo fato de que a espessura da camada de sacrifício (4) depositada sobre o substrato bulk (1) monocristalino deve ser um valor entre 4 nm e 2000 nm.  Process according to any one of claims 7, 8, 9, 10 or 11, characterized in that the thickness of the sacrificial layer (4) deposited on the monocrystalline bulk (1) substrate must be a value between 4 nm and 2000 nm.
13. Processo, de acordo com qualquer uma das reivindicações 9, 10, 11 ou 12, caracterizado pelo fato de que a deposição do filme fino (6) semicondutor sobre a camada de sacrifício (4) é realizada por uma técnica selecionada do grupo compreendendo epitaxia por feixe molecular (MBE) , deposição química em fase de vapor e sputtering. Method according to any one of claims 9, 10, 11 or 12, characterized in that the deposition of the semiconductor thin film (6) on the sacrificial layer (4) is carried out by a technique selected from the group comprising molecular beam epitaxy (MBE), chemical vapor phase deposition and sputtering.
14. Processo, de acordo com qualquer uma das reivindicações 9, 10, 11, 12 ou 13, caracterizado pelo fato de que a deposição do filme fino (6) semicondutor sobre a camada de sacrifício (4) ocorre a uma temperatura entre 400°C e 650°C.  Process according to any one of claims 9, 10, 11, 12 or 13, characterized in that the deposition of the semiconductor thin film (6) on the sacrificial layer (4) occurs at a temperature between 400 ° C. C and 650 ° C.
15. Processo, de acordo com qualquer uma das reivindicações 9, 10, 11, 12, 13 ou 14, caracterizado pelo fato de que a espessura da camada do filme fino (6) semicondutor varia entre 2 nm e 100 nm.  Process according to any one of claims 9, 10, 11, 12, 13 or 14, characterized in that the layer thickness of the semiconductor thin film (6) ranges from 2 nm to 100 nm.
16. Processo, de acordo com qualquer uma das reivindicações 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 ou 15, caracterizado pelo fato de que a remoção seletiva da camada de sacrifício (4) é realizada pelo método de wet-etching em conjunto à técnica de fotolitografia .  Process according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, characterized in that the selective removal of the The sacrificial layer (4) is performed by the wet etching method together with the photolithography technique.
17. Processo, de acordo com a reivindicação 16, caracterizado pelo fato de que o fluido de remoção da camada de sacrifício (4) é escolhido de um grupo de compostos de alta seletividade que solubilizam a camada de sacrifício (4) , como HF.  Process according to Claim 16, characterized in that the sacrificial layer removal fluid (4) is chosen from a group of high selectivity compounds which solubilize the sacrificial layer (4) as HF.
18. Processo, de acordo com qualquer uma das reivindicações 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ou 17, caracterizado pelo fato de que o substrato bulk (7) é constituído por um material abundante e barato, preferencialmente Si.  Process according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17, characterized in that bulk substrate (7) is an abundant and inexpensive material, preferably Si.
19. Processo, de acordo com qualquer uma das reivindicações Process according to any one of the claims
16 ou 17, caracterizado pelo particular posicionamento do substrato virtual (9) sobre o novo substrato (7), definido pela fotolitografia, de modo a permitir sua integração a circuitos semicondutores previamente definidos no novo substrato (7) bulk, como o laser de cavidade vertical e emissão superficial (VCSEL) . 16 or 17, characterized by the particular positioning of the virtual substrate (9) on the new substrate (7), defined by photolithography, to allow its integration with previously defined semiconductor circuits in the new bulk substrate (7), such as the cavity laser vertical and surface emission (VCSEL).
20. Processo, de acordo com qualquer uma das reivindicações 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 ou 19, caracterizado pelo fato de que um tratamento térmico assegura a ligação do substrato virtual (9) ao novo substrato (7) . Process according to any one of Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19, characterized in by the fact that a heat treatment ensures the bonding of the virtual substrate (9) to the new substrate (7).
21. Processo, de acordo com qualquer uma das reivindicações 19 ou 20, caracterizado pelo fato de que ocorre a formação de um sistema de camadas composto pelo substrato virtual (9) e pelo novo substrato (7) bulk. Process according to either of claims 19 or 20, characterized in that a layer system comprising the virtual substrate (9) and the new bulk substrate (7) occurs.
22. Processo, de acordo com qualquer uma das reivindicações Process according to any one of the claims
19, 20 ou 21, caracterizado pelo fato de que a integração ocorre pela formação de contatos elétricos no sistema de camadas por interdifusão . 19, 20 or 21, characterized by the fact that integration occurs by the formation of electrical contacts in the interdiffusion layer system.
23. Processo, de acordo com a reivindicação 1, 2, 19, 20 ou 21, caracterizado pelo fato de que a etapa de limpeza inclui inicialmente a aplicação de pelo menos uma solução selecionada de um grupo compreendendo soluções de ácido sulfúrico, SemiconClean 23 (Furuuchi Chemical Corporation) , dimetil sulfóxido e acetona.  Process according to claim 1, 2, 19, 20 or 21, characterized in that the cleaning step initially includes the application of at least one solution selected from a group comprising solutions of sulfuric acid, SemiconClean 23 ( Furuuchi Chemical Corporation), dimethyl sulfoxide and acetone.
24. Processo, de acordo com a reivindicação 23, caracterizado pelo fato de que a etapa de limpeza inclui a aplicação da solução de limpeza seguida de tratamento térmico para possibilitar crescimento de heteroestruturas semicondutoras sobre o conjunto (10) por crescimento epitaxial.  Process according to Claim 23, characterized in that the cleaning step includes applying the cleaning solution followed by heat treatment to enable growth of semiconductor heterostructures on the assembly (10) by epitaxial growth.
25. Processo, de acordo com qualquer uma das reivindicações Process according to any one of the claims
23 ou 24, caracterizado pelo fato de que a etapa de limpeza é concluída com a aplicação de hidrogénio no sistema de camadas para possibilitar crescimento de heteroestruturas semicondutoras sobre o conjunto (10) por crescimento epitaxial. 23 or 24, characterized in that the cleaning step is completed by applying hydrogen to the layer system to enable growth of semiconductor heterostructures on the assembly (10) by epitaxial growth.
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