WO2010055182A1 - Microelectronic device based on grids of disc and ring microelectrodes, and method for producing said device - Google Patents

Microelectronic device based on grids of disc and ring microelectrodes, and method for producing said device Download PDF

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Publication number
WO2010055182A1
WO2010055182A1 PCT/ES2009/070477 ES2009070477W WO2010055182A1 WO 2010055182 A1 WO2010055182 A1 WO 2010055182A1 ES 2009070477 W ES2009070477 W ES 2009070477W WO 2010055182 A1 WO2010055182 A1 WO 2010055182A1
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layer
dielectric material
metallic level
ring
disk
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PCT/ES2009/070477
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Spanish (es)
French (fr)
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Francisco Javier Del Campo Garcia
Francesc Xavier MUÑOZ PASCUAL
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Consejo Superior De Investigaciones Cientificas (Csic)
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Publication of WO2010055182A1 publication Critical patent/WO2010055182A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells

Definitions

  • the present invention is framed in the scientific-technical area of Chemistry, within the sector of electrochemical applications, in environments where voltammetric techniques are used, such as cyclic voltammetry or amperometry. It can be used in sectors as disparate as water control, the determination of heavy metals or electrochemical parameters of analytical interest, as can also be used as the basis of new biosensors.
  • the main object of the present invention relates to a microelectronic device based on networks of disk and ring microelectrodes and the method of manufacturing thereof. Another objective of the present invention is its application in electrochemical measurements.
  • the rotating electrode is a classic electrochemical tool that allows to maintain a controlled and constant flow of material towards the surface of an electrode. It is one of several techniques known as
  • Rotating electrodes are well known and widely used for both electroanalytical and material characterization studies or measurement of reaction mechanisms and determination of kinetic parameters.
  • a rotating electrode is generally a disk electrode, formed by a metal such as gold, platinum or another, or carbon or carbon derivative, polished and surrounded by a cylindrical insulating material and with which it is concentric. This electrode is coupled to a motor connected to a unit that allows very precise control of the rotation speed, so that reproducible conditions can be obtained. In general, it is sought to generate laminar flow conditions at the electrode-dissolution interface, so that a high and constant supply of material is obtained that results in easy to measure limiting currents.
  • Rotating electrodes are typically used to determine mechanistic parameters such as diffusion coefficients or concentration of a given analyte, the number of electrons involved in a given reaction, reaction constants or parameters related to the viscosity of a medium.
  • a variant of the rotating electrode is known as the rotating ring and disk electrode.
  • This device has its origins in the late 1950s, when Frumkin and Nekrasov Io developed in order to detect unstable reaction intermediates. It consists of a rotating disk electrode surrounded by a concentric insulating ring and then by a second concentric ring electrode.
  • two independently polarizable electrodes which allows the central disk to be used as the "generator” electrode of new chemical species that can be detected in the adjacent annular electrode, which acts as a "collector”. All this allows the determination of reaction kinetic constants, since modulating the speed of rotation of the system achieves higher or lower material contribution rates from the disk to the ring.
  • Microelectrodes are electrodes that generally have at least one dimension of the order of magnitude or less than the thickness of the diffusion layer that is generated when they work. Usually, this dimension is of the order of a few microns.
  • microelectrodes can be manufactured mechanically or lithographically, and are very useful in electroanalysis of very resistive media, or for analyte measurements present at low concentration, or for kinetic measurements of rapid phenomena (compared to what can be measured with a macro electrode or with a rotating electrode). Given their small size, microelectrodes have a number of additional advantages. Among other things, they experience very low ohmic losses ("iR drop"), so they can be used in very resistive media, they also experience very low capacitive currents, since their area is very small. In return, the current that can be measured in a microelectrode is typically very low, of the order of nanoamperes. This forces to work with equipment quite sensitive and in conditions of electrical isolation quite strict.
  • iR drop ohmic losses
  • Microelectrode networks are ordered or random groupings of a more or less large number of microelectrodes, and they can be connected in series or in parallel. In the present invention, we work with microelectrode networks connected in parallel, although individually accessible devices could also be made. In a network of microelectrodes, the currents obtained in each of the microelectrodes that compose it are added, with which it is possible to raise the order of magnitude of the total current and thus facilitate its measurement.
  • the microelectrode networks allow to keep practically all the advantages of the individual microelectrodes, such as the sensitivity and the low capacitive component of the current, in comparison with a macroelectrode that had the same surface area than the area occupied by the network.
  • Most of the microelectrode networks that are used are formed by microdisks, although it is also possible to find microelectrodes of other geometries.
  • the second most studied geometry is the microbands. Initially we worked on individual microbands, followed by the combination of two. The limitation was given by the manufacturing technique. The most common was to start from a thin sheet of metal that was used as an electrode. This sheet was encapsulated in an insulating material, such as glass or some resin, so that when the whole was polished, the edge of the sheet was exposed, giving rise to a microband.
  • the present invention consists of a microelectronic device network of ring and disk microelectrodes arranged in a configuration such that the current is amplified and can allow electrochemical measurements without having to use the commonly used rotating ring-disk electrode with the advantages that this implies.
  • the microelectronic device object of the invention offers several advantages over these known solutions. These advantages are mainly the miniaturization, the lack of need for an expensive rotor system and the possibility of studying rapid chemical processes.
  • the proposed invention not only focuses on a microelectronic device based on ring and disk microelectrode networks, but also describes a method of obtaining it for later use in electrochemical applications where voltammetric techniques are used, being very useful for sectors such as water control, the determination of heavy metals, the determination of electrochemical parameters of analytical interest, and the detection by biosensors.
  • the present invention is based on the manufacture by means of photolithographic techniques of networks of disk and ring microelectrodes on a planar chip for current amplification, thus achieving a remarkably significant miniaturization of the current rotating ring-disk electrodes that are commonly used for the realization of electrochemical means.
  • Optical photolithography equipment such as those commonly used in CMOS processes are subject to limits of resolution, which are currently around a miera. This means that it would not be possible to define motifs well below that size, and this also affects
  • microelectrodes on two different levels Another advantage of manufacturing the microelectrodes on two different levels is that it is possible to make geometries that would otherwise be impossible on a single plane. For example, if it were desired to construct a circular microelectrode surrounded by an annular one, it would be necessary for the ring to be open through the area through which the connection of the disk came out, so that the original geometry would be distorted.
  • the case of the present invention which includes a network formed by many of these disk systems. ring, it would be completely impossible if it were performed on a single level.
  • Other configurations, such as comb-type structures or interdigitated microbands would also benefit from this arrangement in two parallel planes separated by the dielectric layer in contrast to the usual approximation of arranging the microbands in the same plane.
  • both the auxiliary and the reference electrode can be integrated.
  • the effectiveness of the devices increases by decreasing the distance that separates the microelectrodes, because the measured currents are conditioned by the transport of matter and, logically, the smaller the distance through which the molecules have to diffuse, the faster they can pass from one electrode to another, and greater will be the recorded current.
  • microelectronic device based on networks of disk and ring microelectrodes is described on a silicon wafer useful for measuring electrochemical parameters, hereinafter microelectronic device, comprising:
  • a first layer of dielectric material selected, between an oxide, a nitride, a combination of both and a polymer or a resin, which electrically separates and insulates, c) A lower metallic level.
  • a second layer of dielectric material e) A higher metallic level where the microelectrodes are defined.
  • a particular aspect of the invention constitutes the microelectronic device of the invention in which the lower metallic level and the upper metallic level can be constituted from any type of material susceptible to be deposited by techniques compatible with cleanroom processes such as sputtering , evaporation, electroporation or PVD.
  • a particular embodiment of the invention constitutes the microelectronic device of the invention in which the metallic material of the lower metallic level and the upper metallic level is a three-layer titanium, nickel and gold.
  • the thickness of the layer of dielectric material that will be the one that controls the effective distance between the disk microelectrodes located in the lower metallic level and the microelectrodes of ring located in the upper metallic level.
  • This parameter will vary according to the type of insulating material used, and it may be thicker if it is a polymer or a resin; This parameter is also influenced by the type of chip material used.
  • another particular aspect of the invention constitutes the microelectronic device of the invention in which when the dielectric material of the first layer of dielectric material is an oxide, a nitride or a combination of both, the thickness of said layer is comprised between
  • Another particular aspect of the invention constitutes the microelectronic device of the invention in which when the dielectric of the first layer of dielectric material is a polymer or a resin, the thickness of said layer is between 50 nanometers and 100 micrometers.
  • Another particular aspect of the invention constitutes the microelectronic device of the invention in which the planar chip is made of silicon and in which the first layer of dielectric material is of a thickness of at least 0.5 micrometers.
  • the currents obtained in each of the microelectrodes that compose it can be added and can be connected in series or in parallel depending on the application.
  • the inventors have observed that the parallel configuration is that which achieves a greater amplification of the current.
  • another particular aspect of the invention constitutes the microelectronic device of the invention in which the ring and disk microelectrodes that form the networks can be connected in series or in parallel, the parallel being the one that achieves a greater amplification of the stream.
  • Another aspect of the invention constitutes a procedure for obtaining the ring and disk microelectrode network, hereinafter the method of the invention, which is carried out by photolithographic techniques and comprises the following steps: a) Deposition of a layer of dielectric material on a wafer, so that the silicon or material that forms the wafer is insulated with a thickness from 0.6 micrometers, preferably 1 micrometer of oxide. b) First metallization of the wafer obtained in a) by means of the deposition of a metal that will form the discs.
  • Photolithography stage to define the geometry of the discs of the lower metallic level comprising the following sub-stages: i) Insolation through a mask with geometric patterns corresponding, as well as the alignment reasons necessary for the correct definition of the following photolithographic levels. ii) Developed in a solvent bath. iii) Engraving, for example, in a redox attack in an iodine / iodide bath of the areas not protected by the photoresin, in order to remove the metal from the unprotected areas. iv) Pickling with acetone to remove all the resin or by exposure to an oxygen plasma. v) Wafer cleaning by successive washing with deionized water.
  • a particular embodiment of the invention constitutes the process of the invention in which the dielectric material used in step a) is a silicon oxide.
  • Another particular aspect of the invention constitutes the process of
  • Another particular embodiment of the invention constitutes the process of the invention in which the solvent used in the development sub-stage c.ii) of the photolithography stage c) is tetramethyl ammonium hydroxide (TMH).
  • TMH tetramethyl ammonium hydroxide
  • Another particular embodiment of the invention constitutes the process of the invention in which the pickling sub-stage c.iv) of the photolithography stage c) is performed by exposure to an oxygen plasma.
  • the dielectric material used in step d) can be any material with electrical insulation properties selected, for illustrative purposes and without limiting the scope of the invention, to following group: an oxide, a nitride, a combination of both, a polymer or a resin.
  • the mission of this material is twofold: on the one hand electrically and hermetically isolate the metal from the rest, and on the other, control the separation between the disk and the ring.
  • the dielectric material used in step d) is an oxynitride.
  • Another particular embodiment of the invention constitutes the process of the invention in which the dielectric material of g) is a photoresin.
  • This layer of dielectric material must be as thin as possible so as not to limit access to the material by diffusion to the electrodes, both to the rings and to the microelectrodes because at least 0.4 micrometers are buried.
  • This new dielectric must have the minimum material thickness that guarantees electrical isolation of the system.
  • Another particular embodiment of the invention constitutes the process of the invention in which the solvent used in the development sub-stage h.ii) of the photolithography stage h) is tetramethyl ammonium hydroxide (TMH).
  • TSH tetramethyl ammonium hydroxide
  • Another particular aspect of the invention constitutes the process of the invention in which the engraving of the upper dielectric layer h.iv) of the photolithography stage h) is carried out by wet or dry etching.
  • Another particular embodiment of the invention constitutes the process of the invention in which the engraving of the intermediate dielectric layer h.vi) of the photolithography stage h) is carried out by means of the technique of etching by reactive ions.
  • Another aspect of the invention constitutes the use of the microelectronic device of the invention for electrochemical applications such as water control, the determination of heavy metals, the determination of electrochemical parameters of analytical interest, as well as its use as a base of biosensors.
  • the present invention which consists of a network of ring and disk microelectrodes arranged in a specific configuration, achieves that the current is amplified and can allow the realization of Electrochemical measurements without having to use the commonly used rotating ring-disk electrode with the advantages that this entails.
  • these advantages are mainly miniaturization, the lack of need for an expensive rotor system and the possibility of studying rapid chemical processes.
  • Figure 1. Shows the state of the art.
  • Figure 2. Shows the state of the art. A scheme of the rotating disk and ring electrode.
  • FIG. 3 This figure shows a scheme of the diffusion layer, d, on a microelectrode of radius r.
  • FIG. 5 This figure shows the manufacturing steps of the device.
  • FIG. 7 This figure details the different phases of the manufacture of the device.
  • a rotating electrode is comprised of: An insulating material (20).
  • a metal shaft of the electrode which is connected to the rotor (23).
  • the rotating disk and ring electrode is formed by:
  • An insulating material 24.
  • a ring electrode 25.
  • a disk electrode 26).
  • a metal shaft of the electrode which is connected to the rotor (29).
  • an oxide layer of about a thick thickness was grown polished. This oxide layer serves to electrically isolate the silicon wafer (1) from the rest of the device.
  • the metallization of the silicon wafer (1) was carried out. In this If this metallization was carried out by depositing a titanium tricapa (20-50 nm), which acts as an adhesion promoter under a nickel layer (20-50 nm) that acts as a diffusion barrier to avoid mixing the titanium with the gold that is deposits on nickel.
  • the gold layer has a thickness of 50-150 nm.
  • the next step consisted of a photolithography stage that serves to define the geometry of the metallic level where the disks (5) will be defined, as seen in fig. 4, on the final device.
  • a layer of photoresin was deposited on the metallic silicon wafer (1) and it is insoled through a mask with the corresponding geometric motifs, as well as the alignment reasons necessary for the correct definition of the following photolithographic levels.
  • the next step is a passivation stage with oxide. Since it is the thickness of this layer that controls the effective distance between the disk and the ring, its thickness is 1 microns.
  • the oxide grows isotropically over the entire surface.
  • the next stage consists in the definition of the zones in which the second metal will be conserved, by means of a photolithography stage. For this, the result of the previous process is covered with a thin layer of photoresin. Next, it is insoled through a chrome mask in which said motifs have been defined. After exposure, the uncured resin is removed in a bath of the corresponding solvent.
  • the exposed areas of the metal of the upper layer are etched. This is carried out in a wet bath. After this engraving, the resin is removed from the protected areas by immersion in an acetone bath and the result of the previous process is washed in deionized water.
  • the upper metallic level (3) contains a series of holes that will subsequently serve to define the discs (5) of the lower metallic level (2), in a dry attack stage in which the Upper level metal will act as a mask.
  • the next stage consists of a new passivation, although on this occasion it is convenient that the deposited layer be as thin as possible without damaging the electrical insulation of the upper metal layer.
  • the wafer Once the wafer is passivated, it will be subjected to a new photolithographic stage destined to the definition of the disks (5) and the rings (6).
  • the upper layer of oxynitride is attacked, in an etching stage that can be wet or dry. In this stage it is possible to eliminate not only the dielectric of the upper level, but also the dielectric that separates the two metallic levels in the areas defined as disks by the upper metallic level (2). After this engraving, we proceed to Ia Elimination of the photoresin in an acetone bath. After this, a cleaning of the final result is performed to eliminate remains of the previous stages.
  • a process for the manufacture, by photolithographic techniques, of a microelectronic device based on disk and ring microelectrode networks is described.
  • a silicon wafer (1) fig. 6.1 polished an oxide layer of about one thick thickness was grown, a first layer of dielectric material (4) as seen in fig. 6.2. This oxide layer serves to electrically isolate the silicon wafer (1) from the rest of the device.
  • the metallization of the silicon wafer (1) was carried out as shown in fig. 6.3. In the case that the present invention, this metallization was carried out by depositing a titanium three-layer (20-50 nm), which acts as an adhesion promoter under a nickel layer (20-50 nm) that acts as a diffusion barrier to avoid the mixing of the titanium with gold that is deposited on nickel.
  • the gold layer has a thickness, but not limited to, between 50 and 200 nm.
  • the next step consists of a photolithography stage, as seen in fig. 6.4, which serves to define the geometry of the metallic level where the disks (5) will be defined in the final device.
  • a layer of photoresin was deposited on the metallic silicon wafer (1) and insulated through a mask with the corresponding geometric patterns, as well as the alignment reasons necessary for the correct definition of the following photolithographic levels.
  • the uncured resin was removed in a pickling stage, and the result obtained was again cleaned by successive washing with deionized water.
  • the next step as seen in fig. 6.6, consisted of a passivation stage with oxynitride, generating a second layer of dielectric material (7). Since it is the thickness of this layer that controls the effective distance between the disk and the ring, its thickness can be varied between a minimum of 0.5 microns and a maximum of 2 microns, being manufactured with a thickness of oxide of 1 miera . The oxide grows isotropically over the entire surface.
  • the next stage consists in the definition of the zones in which the second metal will be preserved, by means of a photolithography stage as detailed in fig. 6.8.
  • a photolithography stage as detailed in fig. 6.8.
  • the result obtained from the previous process was covered with a thin layer of photoresin. Then, it was insulated through a chrome mask in which said motifs have been defined. After exposure, the uncured resin was removed in a bath of the corresponding solvent.
  • the exposed areas of the metal of the upper layer were etched see fig. 6.9. This was carried out in a wet bath. After this etching, the resin was removed from the protected areas by immersion in an acetone bath and the result obtained in the previous process was washed in deionized water.
  • the next stage consists of a new passivation as seen in fig. 6.10, a third layer of dielectric material (8) although on this occasion it is convenient that the deposited layer be as thin as possible without damaging the electrical insulation of the lower metallic level.
  • the result of the previous process will be subjected to a new series of photolithographic stages, as observed in fig. 6.11 intended for the definition of disks (5) and rings (6).
  • the resin was annealed at 200 ° for 30 minutes, and a new dry attack was carried out to remove the oxynitride from the intermediate layer, thus opening the discs (5).
  • the photoresin was removed in an acetone bath. After this, a cleaning of the result of the previous process was performed to eliminate remains of the previous stages as shown in fig. 6.13.

Abstract

The present invention consists of a microelectronic device based on grids of ring (6) and disc (5) microelectrodes, in which the current is amplified and electrochemical measurements can be carried out without having to use the commonly used rotating ring-disc electrode; the three-dimensional device helps to overcome the resolution limitations imposed by the aligning tool used in the photolithographic stages. The present invention also describes the method for producing said microelectronic device.

Description

DISPOSITIVO MICROELECTRONICO BASADO EN REDES DE MICROELECTRODOS DE DISCO Y ANILLO, Y MÉTODO DE FABRICACIÓN MICROELECTRONIC DEVICE BASED ON DISK AND RING MICROELECTRODE NETWORKS, AND MANUFACTURING METHOD
DEL MISMOOF THE SAME
D E S C R I P C I Ó ND E S C R I P C I Ó N
OBJETO DE LA INVENCIÓNOBJECT OF THE INVENTION
La presente invención se enmarca en el área científico-técnica de Ia Química, dentro del sector de las aplicaciones electroquímicas, en entornos donde se utilicen técnicas voltamperométricas, como Ia voltametría cíclica o Ia amperometría. Puede emplearse en sectores tan dispares como el control de aguas, Ia determinación de metales pesados o de parámetros electroquímicos de interés analítico, como también puede emplearse como base de nuevos biosensores.The present invention is framed in the scientific-technical area of Chemistry, within the sector of electrochemical applications, in environments where voltammetric techniques are used, such as cyclic voltammetry or amperometry. It can be used in sectors as disparate as water control, the determination of heavy metals or electrochemical parameters of analytical interest, as can also be used as the basis of new biosensors.
El objeto principal de Ia presente invención se refiere a un dispositivo microelectrónico basado en redes de microelectrodos de disco y anillo y al método de fabricación del mismo. Otro objetivo de Ia presente invención es su aplicación en mediciones electroquímicas.The main object of the present invention relates to a microelectronic device based on networks of disk and ring microelectrodes and the method of manufacturing thereof. Another objective of the present invention is its application in electrochemical measurements.
ANTECEDENTES DE LA INVENCIÓN.BACKGROUND OF THE INVENTION
El electrodo rotante es una herramienta electroquímica clásica que permite mantener un flujo controlado y constante de material hacia Ia superficie de un electrodo. Es una de las varias técnicas conocidas comoThe rotating electrode is a classic electrochemical tool that allows to maintain a controlled and constant flow of material towards the surface of an electrode. It is one of several techniques known as
"hidrodinámicas", junto a sistemas como celdas de flujo o electrodos de chorro"hydrodynamics", together with systems such as flow cells or jet electrodes
("wall jet", en Inglés). Los electrodos rotantes son muy conocidos y ampliamente utilizados para estudios tanto electroanalíticos como de caracterización de materiales o de medida de mecanismos de reacción y determinación de parámetros cinéticos. Un electrodo rotante es generalmente un electrodo de disco, formado por un metal como oro, platino u otro, o bien carbono o derivado del carbono, pulido y rodeado de un material aislante de forma cilindrica y con el cual resulta concéntrico. Este electrodo se acopla a un motor conectado a una unidad que permite un control muy preciso de Ia velocidad de rotación, de manera que puedan obtenerse condiciones reproducibles. En general se busca generar condiciones de flujo laminar en Ia interfase electrodo-disolución, de manera que se consiga un aporte elevado y constante de material que resulte en corrientes limitantes fáciles de medir. Los electrodos rotantes se emplean típicamente para determinar parámetros mecanísticos tales como coeficientes de difusión o concentración de un determinado analito, el número de electrones que intervienen en una determinada reacción, constantes de reacción o parámetros relacionados con Ia viscosidad de un medio.("wall jet", in English). Rotating electrodes are well known and widely used for both electroanalytical and material characterization studies or measurement of reaction mechanisms and determination of kinetic parameters. A rotating electrode is generally a disk electrode, formed by a metal such as gold, platinum or another, or carbon or carbon derivative, polished and surrounded by a cylindrical insulating material and with which it is concentric. This electrode is coupled to a motor connected to a unit that allows very precise control of the rotation speed, so that reproducible conditions can be obtained. In general, it is sought to generate laminar flow conditions at the electrode-dissolution interface, so that a high and constant supply of material is obtained that results in easy to measure limiting currents. Rotating electrodes are typically used to determine mechanistic parameters such as diffusion coefficients or concentration of a given analyte, the number of electrons involved in a given reaction, reaction constants or parameters related to the viscosity of a medium.
Una variante del electrodo rotante es el conocido como electrodo rotante de anillo y disco. Este dispositivo tiene sus orígenes a finales de los años 1950, cuando Frumkin y Nekrasov Io desarrollaron con el fin de detectar intermedios de reacción inestables. Consiste en un electrodo de disco rotante rodeado por un anillo aislante concéntrico y a continuación por segundo electrodo anular concéntrico. Así se consigue disponer de dos electrodos independientemente polarizables, Io que permite utilizar el disco central como electrodo "generador" de nuevas especies químicas que pueden ser detectadas en el electrodo anular contiguo, que actúa como "colector". Todo esto permite determinar constantes cinéticas de reacción, ya que modulando Ia velocidad de rotación del sistema se consiguen mayores o menores tasas de aporte de materia del disco al anillo. Además de jugar con Ia velocidad de rotación, también es posible variar Ia distancia que separa a ambos electrodos. Cuánto más pequeña sea dicha distancia, más rápidos serán los procesos que se pueden estudiar. Esta capacidad de trabajar con los dos electrodos actuando como "generador" y "colector" también viene aprovechándose en otro tipo de dispositivos de escala micrométrica, conocidos como microelectrodos de doble y triple banda, pero más eficazmente los microelectrodos interdigitados. Los microelectrodos son electrodos que presentan, por Io general, al menos una dimensión del orden de magnitud o inferior al espesor de Ia capa de difusión que se genera cuando trabajan. Habitualmente, esta dimensión es del orden de unas pocas mieras. Los microelectrodos pueden fabricarse mecánica o litográficamente, y son de gran utilidad en electroanálisis de medios muy resistivos, o para medidas de analitos presentes a baja concentración, o para medidas cinéticas de fenómenos rápidos (en comparación con Io que se puede llegar a medir con un macroelectrodo o con un electrodo rotante). Dado su pequeño tamaño, los microelectrodos tienen una serie de ventajas adicionales. Entre otras cosas, experimentan pérdidas ohmicas ("iR drop") muy bajas, por Io que pueden ser empleados en medios muy resistivos, también experimentan corrientes capacitivas muy bajas, ya que su área es muy pequeña. Como contrapartida, Ia corriente que se puede llegar a medir en un microelectrodo es típicamente muy baja, del orden de los nanoamperios. Esto obliga a trabajar con equipos bastante sensibles y en condiciones de aislamiento eléctrico bastante estrictas.A variant of the rotating electrode is known as the rotating ring and disk electrode. This device has its origins in the late 1950s, when Frumkin and Nekrasov Io developed in order to detect unstable reaction intermediates. It consists of a rotating disk electrode surrounded by a concentric insulating ring and then by a second concentric ring electrode. Thus, it is possible to have two independently polarizable electrodes, which allows the central disk to be used as the "generator" electrode of new chemical species that can be detected in the adjacent annular electrode, which acts as a "collector". All this allows the determination of reaction kinetic constants, since modulating the speed of rotation of the system achieves higher or lower material contribution rates from the disk to the ring. In addition to playing with the rotation speed, it is also possible to vary the distance that separates both electrodes. The smaller the distance, the faster the processes that can be studied. This ability to work with the two electrodes acting as "generator" and "collector" is also taking advantage of other types of micrometric scale devices, known as double and triple band microelectrodes, but more effectively interdigitated microelectrodes. Microelectrodes are electrodes that generally have at least one dimension of the order of magnitude or less than the thickness of the diffusion layer that is generated when they work. Usually, this dimension is of the order of a few microns. The microelectrodes can be manufactured mechanically or lithographically, and are very useful in electroanalysis of very resistive media, or for analyte measurements present at low concentration, or for kinetic measurements of rapid phenomena (compared to what can be measured with a macro electrode or with a rotating electrode). Given their small size, microelectrodes have a number of additional advantages. Among other things, they experience very low ohmic losses ("iR drop"), so they can be used in very resistive media, they also experience very low capacitive currents, since their area is very small. In return, the current that can be measured in a microelectrode is typically very low, of the order of nanoamperes. This forces to work with equipment quite sensitive and in conditions of electrical isolation quite strict.
Las redes de microelectrodos son agrupaciones ordenadas o aleatorias de un número más o menos grande de microelectrodos, y que pueden estar conectados en serie o en paralelo. En Ia invención que se presenta se trabaja con de redes de microelectrodos conectados en paralelo, aunque también se podrían hacer dispositivos individualmente accesibles. En una red de microelectrodos se suman las corrientes obtenidas en cada uno de los microelectrodos que Ia componen, con Io que se consigue elevar el orden de magnitud de Ia corriente total y facilitar así su medida. Por otro lado, y operados en condiciones óptimas, las redes de microelectrodos permiten conservar prácticamente todas las ventajas de los microelectrodos individuales, tales como son Ia sensibilidad y Ia baja componente capacitiva de Ia corriente, en comparación con un macroelectrodo que tuviese Ia misma área superficial que el área ocupada por Ia red. La mayoría de las redes de microelectrodos que se utilizan están formadas por microdiscos, aunque también es posible encontrar microelectrodos de otras geometrías. La segunda geometría más estudiada son las microbandas. Inicialmente se trabajó sobre microbandas individuales, seguido de Ia combinación de dos. La limitación venía dada por Ia técnica de fabricación. Lo más habitual era partir de una fina lámina del metal que se quería emplear como electrodo. Esta lámina se encapsulaba en un material aislante, como vidrio o alguna resina, de modo que al pulir el conjunto quedase expuesto el borde de Ia lámina, dando lugar a una microbanda.Microelectrode networks are ordered or random groupings of a more or less large number of microelectrodes, and they can be connected in series or in parallel. In the present invention, we work with microelectrode networks connected in parallel, although individually accessible devices could also be made. In a network of microelectrodes, the currents obtained in each of the microelectrodes that compose it are added, with which it is possible to raise the order of magnitude of the total current and thus facilitate its measurement. On the other hand, and operated in optimal conditions, the microelectrode networks allow to keep practically all the advantages of the individual microelectrodes, such as the sensitivity and the low capacitive component of the current, in comparison with a macroelectrode that had the same surface area than the area occupied by the network. Most of the microelectrode networks that are used are formed by microdisks, although it is also possible to find microelectrodes of other geometries. The second most studied geometry is the microbands. Initially we worked on individual microbands, followed by the combination of two. The limitation was given by the manufacturing technique. The most common was to start from a thin sheet of metal that was used as an electrode. This sheet was encapsulated in an insulating material, such as glass or some resin, so that when the whole was polished, the edge of the sheet was exposed, giving rise to a microband.
Más adelante, con Ia disponibilidad de técnicas fotolitográficas, comienzan a surgir dispositivos en los que hay una multitud de microbandas conectadas de forma alternada en dos electrodos interdigitados. Estos dispositivos se han utilizado principalmente para medidas de impedancia y capacidad, aunque también hay ejemplos de su utilización en amperometría. Los electrodos interdigitados pueden usarse en modo "generador-colector", y sus eficiencias de colección son más altas que en los electrodos de dos o tres microbandas. Su misión es similar a Ia del disco rotatorio, aunque las implicaciones teóricas difieren en parte.Later, with the availability of photolithographic techniques, devices begin to emerge in which there are a multitude of microbands connected alternately on two interdigitated electrodes. These devices have been used mainly for impedance and capacity measurements, although there are also examples of their use in amperometry. Interdigitated electrodes can be used in "generator-collector" mode, and their collection efficiencies are higher than in electrodes with two or three microbands. Its mission is similar to that of the rotating disk, although the theoretical implications differ in part.
DESCRIPCIÓN DE LA INVENCIÓNDESCRIPTION OF THE INVENTION
La presente invención consiste en un dispositivo microelectrónico red de microelectrodos de anillo y disco dispuestos en una configuración tal que consigue que Ia corriente se amplifique y pueda permitir Ia realización de medidas electroquímicas sin tener que utilizar el comúnmente usado electrodo rotante de anillo-disco con las ventajas que esto supone. Como se ha descrito anteriormente en el estado de Ia técnica, hay múltiples soluciones para realizar mediciones; el dispositivo microelectrónico objeto de Ia invención ofrece varias ventajas sobre estas soluciones conocidas. Estas ventajas son principalmente Ia miniaturización, Ia falta de necesidad de disponer de un caro sistema rotor y Ia posibilidad de estudiar procesos químicos rápidos. A su vez la invención propuesta no sólo se centra en un dispositivo microelectrónico basado en redes de microelectrodos de anillo y disco, sino que además describe un procedimiento de obtención para su posterior uso en aplicaciones electroquímicas donde se utilicen técnicas voltamperométricas, siendo de gran utilidad para sectores como el control de aguas, Ia determinación de metales pesados, Ia determinación de parámetros electroquímicos de interés analítico, y Ia detección mediante biosensores.The present invention consists of a microelectronic device network of ring and disk microelectrodes arranged in a configuration such that the current is amplified and can allow electrochemical measurements without having to use the commonly used rotating ring-disk electrode with the advantages that this implies. As described previously in the state of the art, there are multiple solutions to perform measurements; The microelectronic device object of the invention offers several advantages over these known solutions. These advantages are mainly the miniaturization, the lack of need for an expensive rotor system and the possibility of studying rapid chemical processes. In turn, the proposed invention not only focuses on a microelectronic device based on ring and disk microelectrode networks, but also describes a method of obtaining it for later use in electrochemical applications where voltammetric techniques are used, being very useful for sectors such as water control, the determination of heavy metals, the determination of electrochemical parameters of analytical interest, and the detection by biosensors.
La presente invención se basa en Ia fabricación mediante técnicas fotolitográficas de redes de microelectrodos de disco y de anillo sobre un chip planar para Ia amplificación de corriente, logrando de este modo una miniaturización notablemente significativa de los actuales electrodos rotantes de anillo-disco que son comúnmente usados para Ia realización de medias electroquímicas.The present invention is based on the manufacture by means of photolithographic techniques of networks of disk and ring microelectrodes on a planar chip for current amplification, thus achieving a remarkably significant miniaturization of the current rotating ring-disk electrodes that are commonly used for the realization of electrochemical means.
Así pues se superan los límites de resolución de Ia alineadora en el paso fotolitográfico y se facilita Ia posibilidad de nuevas geometrías.Thus, the resolution limits of the aligner in the photolithographic step are exceeded and the possibility of new geometries is facilitated.
Los equipos de fotolitografía ópticos como los utilizados habitualmente en procesos CMOS están sujetos a unos límites de resolución, que en Ia actualidad se encuentran en torno a una miera. Esto quiere decir que no sería posible definir motivos muy por debajo de ese tamaño, y esto también afecta aOptical photolithography equipment such as those commonly used in CMOS processes are subject to limits of resolution, which are currently around a miera. This means that it would not be possible to define motifs well below that size, and this also affects
Ia separación entre motivos.The separation between motives.
Otra ventaja de fabricar los microelectrodos en dos niveles diferentes es que se hace posible realizar geometrías que de otro modo resultarían imposibles en un único plano. Por ejemplo, si se deseara construir un microelectrodo circular rodeado por otro anular, sería necesario que el anillo estuviese abierto por Ia zona a través de Ia que saliera Ia conexión del disco, con Io que Ia geometría original quedaría desvirtuada. El caso de Ia presente invención, que incluye una red formada por muchos de estos sistemas disco- anillo, resultaría del todo imposible si se realizara en un solo nivel. Otras configuraciones, como por ejemplo estructuras de tipo peine o microbandas interdigitadas, también se verían beneficiadas por esta disposición en dos planos paralelos separados por Ia capa de dieléctrico en contraste con Ia aproximación habitual de disponer las microbandas en el mismo plano.Another advantage of manufacturing the microelectrodes on two different levels is that it is possible to make geometries that would otherwise be impossible on a single plane. For example, if it were desired to construct a circular microelectrode surrounded by an annular one, it would be necessary for the ring to be open through the area through which the connection of the disk came out, so that the original geometry would be distorted. The case of the present invention, which includes a network formed by many of these disk systems. ring, it would be completely impossible if it were performed on a single level. Other configurations, such as comb-type structures or interdigitated microbands, would also benefit from this arrangement in two parallel planes separated by the dielectric layer in contrast to the usual approximation of arranging the microbands in the same plane.
Una de las ventajas de disponer de una red de microelectrodos de disco y anillo, en comparación con un sistema de electrodo rotante de disco y anillo es que se elimina Ia necesidad de un sistema rotor, ya que aprovechamos las altas tasas de transporte de materia que caracterizan el comportamiento de los microelectrodos y también se consigue un mayor nivel de miniaturización del montaje experimental.One of the advantages of having a network of disk and ring microelectrodes, compared to a rotating disk and ring electrode system, is that the need for a rotor system is eliminated, since we take advantage of the high material transport rates that they characterize the behavior of the microelectrodes and a higher level of miniaturization of the experimental assembly is also achieved.
Debido al reducido tamaño del dispositivo, es posible trabajar con volúmenes de muestra más pequeños que con un electrodo rotante convencional, donde el diámetro del electrodo es de al menos un centímetro.Due to the small size of the device, it is possible to work with smaller sample volumes than with a conventional rotating electrode, where the diameter of the electrode is at least one centimeter.
Además del espacio que ocupa el electrodo rotante, también es necesario contar en el sistema con un electrodo auxiliar y con otro de referencia. En el caso de trabajar con chips, tanto el electrodo auxiliar como el de referencia pueden integrarse.In addition to the space occupied by the rotating electrode, it is also necessary to have an auxiliary electrode and a reference electrode in the system. In the case of working with chips, both the auxiliary and the reference electrode can be integrated.
El hecho reducir Ia separación entre microelectrodos por debajo de una miera permite al electroquímico medir procesos cinéticos rápidos (>5x103 s"1) con un bipotenciostato convencional y a velocidades de barrido moderadas. Esto también implica que se puedan medir procesos ultra-rápidos si se dispone de un potenciostato rápido. En este sentido, cabe destacar que este tipo de potenciostatos rápidos muestran plenamente sus posibilidades trabajando con microelectrodos, ya que éstos experimentan corrientes capacitivas y caídas óhmicas muy por debajo de las sufridas por electrodos convencionales (macroelectrodos). Como se desprende de las características y ventajas anteriormente descritas, el hecho de hacer el dispositivo tridimensional ayuda a superar las limitaciones de resolución impuestas por Ia alineadora empleada en las etapas fotolitográficas.The fact of reducing the separation between microelectrodes below one bead allows the electrochemist to measure fast kinetic processes (> 5x10 3 s "1 ) with a conventional biphoteniostat and at moderate scanning speeds. This also implies that ultra-fast processes can be measured if It has a fast potentiostat.In this regard, it should be noted that this type of fast potentiostats fully show their possibilities working with microelectrodes, since they experience capacitive currents and ohmic drops well below those suffered by conventional electrodes (macroelectrodes). As can be seen from the characteristics and advantages described above, the fact of making the three-dimensional device helps to overcome the resolution limitations imposed by the aligner used in the photolithographic stages.
Las máquinas más usuales utilizadas para realizar fotolitografía en obleas con metales nobles (oro, platino e iridio, por poner tres ejemplos) tienen una resolución de entre tres y cinco mieras. Esto quiere decir que Ia mínima separación que se puede obtener entre electrodos dispuestos en el mismo plano sería de al menos 3 a 5 mieras. Al pasar a una configuración tridimensional se puede llegar a separar los electrodos media miera sin demasiada dificultad.The most usual machines used to perform photolithography in wafers with noble metals (gold, platinum and iridium, to give three examples) have a resolution of between three and five microns. This means that the minimum separation that can be obtained between electrodes arranged in the same plane would be at least 3 to 5 microns. When moving to a three-dimensional configuration, you can separate the electrodes halfway without too much difficulty.
La eficacia de los dispositivos aumenta al disminuir Ia distancia que separa los microelectrodos, porque las corrientes medidas están condicionadas por el transporte de materia y, lógicamente, cuanto menor sea Ia distancia a través de Ia cual tienen que difundir las moléculas, más rápido podrán pasar de un electrodo a otro, y mayor será Ia corriente registrada.The effectiveness of the devices increases by decreasing the distance that separates the microelectrodes, because the measured currents are conditioned by the transport of matter and, logically, the smaller the distance through which the molecules have to diffuse, the faster they can pass from one electrode to another, and greater will be the recorded current.
Así pues, en un primer aspecto de Ia invención se describe un dispositivo microelectrónico basado en redes de microelectrodos de disco y anillo sobre una oblea de silicio útil para medir parámetros electroquímicos, en adelante dispositivo microelectrónico, que comprende:Thus, in a first aspect of the invention a microelectronic device based on networks of disk and ring microelectrodes is described on a silicon wafer useful for measuring electrochemical parameters, hereinafter microelectronic device, comprising:
a) Un chip planar formado a partir de una oblea de un material semiconductor seleccionado entre silicio, pírex, cuarzo y carburo de silicio. b) Una primera capa de material dieléctrico seleccionado, entre un óxido, un nitruro, una combinación de ambos y un polímero o una resina, que separa y aisla eléctricamente, c) Un nivel metálico inferior. d) Una segunda capa de material dieléctrico. e) Un nivel metálico superior donde se encuentran definidos los microelectrodos. f) Una tercera capa de material dieléctrico; seleccionado entre un óxido, un nitruro, una combinación de ambos y un polímero o una resina, donde se encuentran definidos también los puntos de conexión. g) Anillos definidos en el nivel metálico superior y discos definidos en el nivel metálico inferior.a) A planar chip formed from a wafer of a semiconductor material selected from silicon, pyrex, quartz and silicon carbide. b) A first layer of dielectric material selected, between an oxide, a nitride, a combination of both and a polymer or a resin, which electrically separates and insulates, c) A lower metallic level. d) A second layer of dielectric material. e) A higher metallic level where the microelectrodes are defined. f) A third layer of dielectric material; selected from an oxide, a nitride, a combination of both and a polymer or a resin, where the connection points are also defined. g) Rings defined in the upper metallic level and discs defined in the lower metallic level.
Un aspecto particular de Ia invención Io constituye el dispositivo microelectrónico de Ia invención en el que el nivel metálico inferior y el nivel metálico superior pueden ser constituidos a partir de cualquier tipo de material susceptible a ser depositado por técnicas compatibles con procesos de sala blanca como sputtering, evaporación, electroporación o PVD. Una realización particular de Ia invención Io constituye el dispositivo microelectrónico de Ia invención en el que el material metálico del nivel metálico inferior y del nivel metálico superior es una tricapa de titanio, níquel y oro.A particular aspect of the invention constitutes the microelectronic device of the invention in which the lower metallic level and the upper metallic level can be constituted from any type of material susceptible to be deposited by techniques compatible with cleanroom processes such as sputtering , evaporation, electroporation or PVD. A particular embodiment of the invention constitutes the microelectronic device of the invention in which the metallic material of the lower metallic level and the upper metallic level is a three-layer titanium, nickel and gold.
Con el fin de optimizar Ia amplificación de Ia corriente, uno de los aspectos de importante relevancia radica en el espesor de Ia capa de material dieléctrico que será Ia que controle Ia distancia efectiva entre los microelectrodos de disco situados en el nivel metálico inferior y los microelectrodos de anillo situados en el nivel metálico superior. Este parámetro variará según el tipo de material aislante que se utilice, pudiendo ser de mayor espesor si éste es un polímero o una resina; este parámetro está influenciado también por el tipo de material del chip utilizado.In order to optimize the amplification of the current, one of the aspects of important relevance lies in the thickness of the layer of dielectric material that will be the one that controls the effective distance between the disk microelectrodes located in the lower metallic level and the microelectrodes of ring located in the upper metallic level. This parameter will vary according to the type of insulating material used, and it may be thicker if it is a polymer or a resin; This parameter is also influenced by the type of chip material used.
Así pues, otro aspecto particular de Ia invención Io constituye el dispositivo microelectrónico de Ia invención en el que cuando el material dieléctrico de Ia primera capa de material dieléctrico es un óxido, un nitruro o una combinación de ambos, el espesor de dicha capa está comprendido entreThus, another particular aspect of the invention constitutes the microelectronic device of the invention in which when the dielectric material of the first layer of dielectric material is an oxide, a nitride or a combination of both, the thickness of said layer is comprised between
400 nanómetros y 2 micrómetros. Otro aspecto particular de Ia invención Io constituye el dispositivo microelectrónico de Ia invención en el que cuando el dieléctrico de Ia primera capa de material dieléctrico es un polímero o una resina, el espesor de dicha capa está comprendido entre 50 nanómetros y 100 micrómetros. Otro aspecto particular de Ia invención Io constituye el dispositivo microelectrónico de Ia invención en el que el chip planar es de silicio y en el que Ia primera capa de material dieléctrico es de un espesor de, al menos 0.5 micrómetros.400 nanometers and 2 micrometers. Another particular aspect of the invention constitutes the microelectronic device of the invention in which when the dielectric of the first layer of dielectric material is a polymer or a resin, the thickness of said layer is between 50 nanometers and 100 micrometers. Another particular aspect of the invention constitutes the microelectronic device of the invention in which the planar chip is made of silicon and in which the first layer of dielectric material is of a thickness of at least 0.5 micrometers.
Tal como se ha comentado en el estado de Ia técnica en una red de microelectrodos se suman las corrientes obtenidas en cada uno de los microelectrodos que Ia componen y pueden estar conectados en serie o en paralelo en función de Ia aplicación. En Ia presente invención los inventores han observado que Ia configuración en paralelo es Ia que logra una mayor amplificación de Ia corriente. Así pues, otro aspecto particular de Ia invención Io constituye el dispositivo microelectrónico de Ia invención en el que los microelectrodos de anillo y disco que forman las redes pueden estar conectados en serie o en paralelo, siendo el paralelo el que logra una mayor amplificación de Ia corriente.As mentioned in the state of the art in a network of microelectrodes, the currents obtained in each of the microelectrodes that compose it can be added and can be connected in series or in parallel depending on the application. In the present invention, the inventors have observed that the parallel configuration is that which achieves a greater amplification of the current. Thus, another particular aspect of the invention constitutes the microelectronic device of the invention in which the ring and disk microelectrodes that form the networks can be connected in series or in parallel, the parallel being the one that achieves a greater amplification of the stream.
Otro aspecto de Ia invención Io constituye un procedimiento de obtención de Ia red de microelectrodos de anillo y disco, en adelante procedimiento de Ia invención, que se realiza mediante técnicas fotolitográficas y comprende las siguientes etapas: a) Deposición de una capa de material dieléctrico sobre una oblea, de tal forma que el silicio o material que forma Ia oblea quede aislado con un espesor a partir de 0.6 micrómetros, preferentemente de 1 micrómetro de óxido. b) Primera metalización de Ia oblea obtenida en a) mediante Ia deposición de un metal que formará los discos. c) Etapa de fotolitografía para definir Ia geometría de los discos del nivel metálico inferior que comprende las siguientes subetapas: i) Insolación a través de una máscara con los motivos geométricos correspondientes, así como los motivos de alineamiento necesarios para Ia correcta definición de los siguientes niveles fotolitográficos. ii) Revelado en un baño de disolvente. iii) Grabado consistente, por ejemplo, en un ataque redox en un baño de yodo/yoduro de las zonas no protegidas por Ia fotoresina, a fin de eliminar el metal de las zonas no protegidas. iv) Decapado con acetona para eliminar toda Ia resina o mediante exposición a un plasma de oxígeno. v) Limpiado de Ia oblea mediante sucesivos lavados con agua desionizada. d) Deposición de una capa de material dieléctrico con propiedades de aislamiento eléctrico sobre Ia oblea. e) Segunda metalización en el que se deposita el segundo nivel de metal que servirá para definir los anillos. f) Etapa de fotolitografía para definir Ia geometría de los planos que contendrán los microelectrodos anulares del nivel metálico superior que comprende las siguientes subetapas: i) Ataque húmedo del metal, ii) Decapado de Ia resina. g) Deposición de una nueva capa de material dieléctrico que será Io más delgada posible, para mantener aislado eléctricamente al segundo metal. h) Definición de los discos situados en el nivel metálico superior, y que marcan el diámetro exterior de los anillos, y del contacto correspondiente que comprende las siguientes subetapas: i) Insolación a través de una máscara de cromo o una transparencia en Ia que se han definido los motivos correspondientes a los microelectrodos situados en el nivel metálico superior. ii) Revelado en un baño de disolvente. iii) Grabado de Ia capa de dieléctrico superior, iv) Grabado de Ia capa intermedia de dieléctrico. v) Eliminación de Ia resina de las zonas protegidas en un baño de acetona. vi) Limpiado de Ia oblea mediante sucesivos lavados con agua desionizada.Another aspect of the invention constitutes a procedure for obtaining the ring and disk microelectrode network, hereinafter the method of the invention, which is carried out by photolithographic techniques and comprises the following steps: a) Deposition of a layer of dielectric material on a wafer, so that the silicon or material that forms the wafer is insulated with a thickness from 0.6 micrometers, preferably 1 micrometer of oxide. b) First metallization of the wafer obtained in a) by means of the deposition of a metal that will form the discs. c) Photolithography stage to define the geometry of the discs of the lower metallic level comprising the following sub-stages: i) Insolation through a mask with geometric patterns corresponding, as well as the alignment reasons necessary for the correct definition of the following photolithographic levels. ii) Developed in a solvent bath. iii) Engraving, for example, in a redox attack in an iodine / iodide bath of the areas not protected by the photoresin, in order to remove the metal from the unprotected areas. iv) Pickling with acetone to remove all the resin or by exposure to an oxygen plasma. v) Wafer cleaning by successive washing with deionized water. d) Deposition of a layer of dielectric material with electrical insulation properties on the wafer. e) Second metallization in which the second level of metal that will serve to define the rings is deposited. f) Photolithography stage to define the geometry of the planes that will contain the annular microelectrodes of the upper metal level comprising the following sub-stages: i) Wet metal attack, ii) Pickling of the resin. g) Deposition of a new layer of dielectric material that will be as thin as possible, to keep the second metal electrically isolated. h) Definition of the disks located in the upper metallic level, and that mark the outer diameter of the rings, and of the corresponding contact comprising the following sub-stages: i) Insolation through a chrome mask or a transparency in which they have defined the reasons corresponding to the microelectrodes located in the upper metallic level. ii) Developed in a solvent bath. iii) Engraving of the upper dielectric layer, iv) Engraving of the intermediate dielectric layer. v) Removal of the resin from the protected areas in an acetone bath. vi) Wafer cleaning by successive washing with deionized water.
Después de todo el proceso descrito, una realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que el material dieléctrico usado en Ia etapa a) es un óxido de silicio. Otro aspecto particular de Ia invención Io constituye el procedimiento deAfter all the described process, a particular embodiment of the invention constitutes the process of the invention in which the dielectric material used in step a) is a silicon oxide. Another particular aspect of the invention constitutes the process of
Ia invención en el que Ia metalización de b) se lleva a cabo con un material susceptible a ser depositado por técnicas compatibles con procesos de sala blanca como sputtering, evaporación, electroporación o PVD, perteneciente, a título ilustrativo y sin que limite el alcance de Ia invención, al siguiente grupo: tricapa de titanio, níquel y oro, oro sobre cromo y oro directamente sobre el sustrato.The invention in which the metallization of b) is carried out with a material capable of being deposited by techniques compatible with cleanroom processes such as sputtering, evaporation, electroporation or PVD, belonging, by way of illustration and without limiting the scope of The invention, to the following group: titanium, nickel and gold trilayer, gold on chromium and gold directly on the substrate.
Otra realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que el disolvente usado en Ia subetapa de revelado c.ii) de Ia etapa de fotolitografía c) es el hidróxido de tetrametil amonio (TMH). Otra realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que Ia subetapa de decapado c.iv) de Ia etapa de fotolitografía c) se realiza mediante exposición a un plasma de oxígeno.Another particular embodiment of the invention constitutes the process of the invention in which the solvent used in the development sub-stage c.ii) of the photolithography stage c) is tetramethyl ammonium hydroxide (TMH). Another particular embodiment of the invention constitutes the process of the invention in which the pickling sub-stage c.iv) of the photolithography stage c) is performed by exposure to an oxygen plasma.
Otro aspecto particular de Ia invención Io constituye el procedimiento de Ia invención en el que el material dieléctrico usado en Ia etapa d) puede ser cualquier material con propiedades de aislamiento eléctrico seleccionado, a título ilustrativo y sin que limite el alcance de Ia invención, al siguiente grupo: un óxido, un nitruro, una combinación de ambos, un polímero o una resina. La misión de este material es doble: por un lado aislar eléctrica y herméticamente el metal del resto, y por otro, controlar Ia separación entre el disco y el anillo. Otra realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que el material dieléctrico usado en Ia etapa d) es un oxinitruro.Another particular aspect of the invention constitutes the process of the invention in which the dielectric material used in step d) can be any material with electrical insulation properties selected, for illustrative purposes and without limiting the scope of the invention, to following group: an oxide, a nitride, a combination of both, a polymer or a resin. The mission of this material is twofold: on the one hand electrically and hermetically isolate the metal from the rest, and on the other, control the separation between the disk and the ring. Another particular embodiment of the invention constitutes the process of the invention in which the dielectric material used in step d) is an oxynitride.
Otra realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que el material dieléctrico de g) es una fotoresina. Esta capa de material dieléctrico debe ser Io más delgada posible a fin de no limitar el acceso al material por difusión a los electrodos, tanto a los anillos como a los microelectrodos porque están enterrados al menos 0.4 micrómetros. Este nuevo dieléctrico debe presentar el espesor mínimo de material que garantiza asilamiento eléctrico del sistema. En el caso de Ia realización de Ia invención, como se utiliza una capa mixta de oxido y nitruro, debe ser al menos 0.5 mieras.Another particular embodiment of the invention constitutes the process of the invention in which the dielectric material of g) is a photoresin. This layer of dielectric material must be as thin as possible so as not to limit access to the material by diffusion to the electrodes, both to the rings and to the microelectrodes because at least 0.4 micrometers are buried. This new dielectric must have the minimum material thickness that guarantees electrical isolation of the system. In the case of the embodiment of the invention, as a mixed layer of oxide and nitride is used, it must be at least 0.5 microns.
Otra realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que el disolvente usado en Ia subetapa de revelado h.ii) de Ia etapa de fotolitografía h) es el hidróxido de tetrametil amonio (TMH).Another particular embodiment of the invention constitutes the process of the invention in which the solvent used in the development sub-stage h.ii) of the photolithography stage h) is tetramethyl ammonium hydroxide (TMH).
Otro aspecto particular de Ia invención Io constituye el procedimiento de Ia invención en el que el grabado de Ia capa de dieléctrico superior h.iv) de Ia etapa de fotolitografía h) se lleva a cabo mediante grabado húmedo o seco.Another particular aspect of the invention constitutes the process of the invention in which the engraving of the upper dielectric layer h.iv) of the photolithography stage h) is carried out by wet or dry etching.
Otra realización particular de Ia invención Io constituye el procedimiento de Ia invención en el que el grabado de Ia capa intermedia de dieléctrico h.vi) de Ia etapa de fotolitografía h) se lleva a cabo mediante Ia técnica de de grabado por iones reactivos.Another particular embodiment of the invention constitutes the process of the invention in which the engraving of the intermediate dielectric layer h.vi) of the photolithography stage h) is carried out by means of the technique of etching by reactive ions.
Otro aspecto de Ia invención Io constituye el uso del dispositivo microelectrónico de Ia invención para aplicaciones electroquímicas como el control de aguas, Ia determinación de metales pesados, Ia determinación de parámetros electroquímicos de interés analítico, así como su uso como base de biosensores.Another aspect of the invention constitutes the use of the microelectronic device of the invention for electrochemical applications such as water control, the determination of heavy metals, the determination of electrochemical parameters of analytical interest, as well as its use as a base of biosensors.
En resumen, Ia presente invención, que consiste en una red de microelectrodos de anillo y disco dispuestos en una configuración específica, consigue que Ia corriente se amplifique y pueda permitir Ia realización de medidas electroquímicas sin tener que utilizar el comúnmente usado electrodo rotante de anillo-disco con las ventajas que esto supone. Como se ha mencionado anteriormente, estas ventajas son principalmente Ia miniaturización, Ia falta de necesidad de disponer de un caro sistema rotor y Ia posibilidad de estudiar procesos químicos rápidos.In summary, the present invention, which consists of a network of ring and disk microelectrodes arranged in a specific configuration, achieves that the current is amplified and can allow the realization of Electrochemical measurements without having to use the commonly used rotating ring-disk electrode with the advantages that this entails. As mentioned above, these advantages are mainly miniaturization, the lack of need for an expensive rotor system and the possibility of studying rapid chemical processes.
DESCRIPCIÓN DE LOS DIBUJOSDESCRIPTION OF THE DRAWINGS
Para complementar Ia descripción que se está realizando y con objeto de ayudar a una mejor comprensión de las características de Ia invención, de acuerdo con un ejemplo preferente de realización práctica de Ia misma, se acompaña como parte integrante de dicha descripción, un juego de dibujos en donde con carácter ilustrativo y no limitativo, se ha representado Io siguiente:To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. where, for the purposes of illustration and not limitation, the following has been represented:
Figura 1.- Muestra el estado de Ia técnica. Un esquema del electrodo rotante.Figure 1.- Shows the state of the art. A scheme of the rotating electrode.
Figura 2.- Muestra el estado de Ia técnica. Un esquema del electrodo rotante de disco y anillo.Figure 2.- Shows the state of the art. A scheme of the rotating disk and ring electrode.
Figura 3.- Esta figura muestra un esquema de Ia capa de difusión, d, sobre un microelectrodo de radio r.Figure 3.- This figure shows a scheme of the diffusion layer, d, on a microelectrode of radius r.
Figura 4.- Esta figura muestra un dispositivo acabado y detalle de sus partes.Figure 4.- This figure shows a finished device and detail of its parts.
Figura 5.- En esta figura se aprecian los pasos de fabricación del dispositivo.Figure 5.- This figure shows the manufacturing steps of the device.
Figura 6.- En esta figura se muestra un detalle del dispositivo acabado.Figure 6.- This figure shows a detail of the finished device.
Figura 7.- Esta figura detalla las distintas fases de Ia fabricación del dispositivo.Figure 7.- This figure details the different phases of the manufacture of the device.
REALIZACIÓN PREFERENTE DE LA INVENCIÓN. Para un mejor entendimiento de Ia invención a continuación se describen unos ejemplos de realización de Ia misma:PREFERRED EMBODIMENT OF THE INVENTION. For a better understanding of the invention, some examples of embodiment thereof are described below:
Ejemplo 1Example 1
Tal y como se desprende de las figura 1 y 2, donde se puede ver una representación esquemática del estado de Ia técnica, el dispositivo objeto de Ia invención se basa en estos conceptos.As shown in Figures 1 and 2, where a schematic representation of the state of the art can be seen, the device object of the invention is based on these concepts.
Como se desprende de Ia figura 1 donde se representa el estado de Ia técnica, un electrodo rotante está comprendido por: Un material aislante (20). Un electrodo de disco (21 ). - Un contacto entre el disco y el eje metálico del electrodo (22).As can be seen from Figure 1 where the state of the art is represented, a rotating electrode is comprised of: An insulating material (20). A disk electrode (21). - A contact between the disk and the metal shaft of the electrode (22).
Un eje metálico del electrodo, que se conecta al rotor (23).A metal shaft of the electrode, which is connected to the rotor (23).
Tal y como muestra Ia figura 2, donde se representa el estado de Ia técnica, el electrodo rotante de disco y anillo está formado por:As shown in Figure 2, where the state of the art is represented, the rotating disk and ring electrode is formed by:
Un material aislante (24). Un electrodo de anillo (25). Un electrodo de disco (26).An insulating material (24). A ring electrode (25). A disk electrode (26).
Un contacto entre el electrodo de disco y el eje metálico del electrodo (27).A contact between the disk electrode and the metal shaft of the electrode (27).
Un contacto del electrodo de anillo (28).A ring electrode contact (28).
Un eje metálico del electrodo, que se conecta al rotor (29).A metal shaft of the electrode, which is connected to the rotor (29).
A continuación se detalla una ejemplo de aplicación, más concretamente se describe un proceso de fabricación del dispositivo objeto de Ia invención.An example of application is detailed below, more specifically a manufacturing process of the device object of the invention is described.
A partir de una oblea de silicio (1 ), ver fig.4, pulida se hizo crecer una capa de óxido de alrededor de una miera de espesor. Esta capa de óxido sirve para aislar eléctricamente Ia oblea de silicio (1 ) del resto del dispositivo. A continuación, se llevó a cabo Ia metalización de Ia oblea de silicio (1 ). En este caso esta metalización se realizó depositando una tricapa de titanio (20-50 nm), que actúa como promotor de adherencia bajo una capa de níquel (20-50 nm) que actúa como barrera difusional para evitar Ia mezcla del titanio con el oro que se deposita sobre el níquel. La capa de oro tiene un espesor de 50-150 nm.From a silicon wafer (1), see fig. 4, an oxide layer of about a thick thickness was grown polished. This oxide layer serves to electrically isolate the silicon wafer (1) from the rest of the device. Next, the metallization of the silicon wafer (1) was carried out. In this If this metallization was carried out by depositing a titanium tricapa (20-50 nm), which acts as an adhesion promoter under a nickel layer (20-50 nm) that acts as a diffusion barrier to avoid mixing the titanium with the gold that is deposits on nickel. The gold layer has a thickness of 50-150 nm.
El siguiente paso consistió en una etapa de fotolitografía que sirve para definir Ia geometría del nivel metálico donde quedarán definidos los discos (5), tal y como se ve en Ia fig. 4, en el dispositivo final. Para ello, se depositó una capa de fotoresina sobre Ia oblea de silicio (1 ) metalizada y se insola a través de una máscara con los motivos geométricos correspondientes, así como los motivos de alineamiento necesarios para Ia correcta definición de los siguientes niveles fotolitográficos.The next step consisted of a photolithography stage that serves to define the geometry of the metallic level where the disks (5) will be defined, as seen in fig. 4, on the final device. For this, a layer of photoresin was deposited on the metallic silicon wafer (1) and it is insoled through a mask with the corresponding geometric motifs, as well as the alignment reasons necessary for the correct definition of the following photolithographic levels.
Una vez insolada, se revela en un baño de disolvente capaz de eliminarOnce insolated, it is revealed in a solvent bath capable of removing
Ia resina no curada. El siguiente paso consiste en grabar, eliminando el metal de las zonas no protegidas por Ia fotoresina. Finalmente, se elimina toda Ia resina en una etapa de decapado, y se procede a limpiar de nuevo el resultado mediante sucesivos lavados con agua desionizada.The uncured resin. The next step is to burn, removing the metal from the areas not protected by the photoresin. Finally, all the resin is removed in a pickling stage, and the result is cleaned again by successive washing with deionized water.
El siguiente paso consiste en una etapa de pasivación con óxido. Dado que es el espesor de esta capa el que controla Ia distancia efectiva entre el disco y el anillo, su espesor es de 1 mieras. El óxido crece de forma isotrópica sobre toda Ia superficie.The next step is a passivation stage with oxide. Since it is the thickness of this layer that controls the effective distance between the disk and the ring, its thickness is 1 microns. The oxide grows isotropically over the entire surface.
A continuación, se lleva a cabo una nueva metalización de Ia oblea final, utilizando para ello Ia tri-capa descrita anteriormente. En este nivel de metal quedarán definidos los electrodos anulares que rodearán a los discos (5). Aunque en este caso el metal utilizado es oro, es posible utilizar cualquier otro metal susceptible de ser depositado por sputtering, evaporación, electrodeposición, PVD o, en general, cualquier técnica compatible con procesos de sala blanca. La siguiente etapa consiste en Ia definición de las zonas en las que se conservará el segundo metal, mediante una etapa de fotolitografía. Para ello se cubre Ia el resultado del proceso anterior con una fina capa de fotoresina. A continuación, se insola a través de una máscara de cromo en Ia que se han definido dichos motivos. Tras Ia exposición, se elimina Ia resina no curada en un baño del disolvente correspondiente.Next, a new metallization of the final wafer is carried out, using the tri-layer described above. In this metal level the annular electrodes that will surround the disks (5) will be defined. Although in this case the metal used is gold, it is possible to use any other metal that can be deposited by sputtering, evaporation, electrodeposition, PVD or, in general, any technique compatible with cleanroom processes. The next stage consists in the definition of the zones in which the second metal will be conserved, by means of a photolithography stage. For this, the result of the previous process is covered with a thin layer of photoresin. Next, it is insoled through a chrome mask in which said motifs have been defined. After exposure, the uncured resin is removed in a bath of the corresponding solvent.
Tras el revelado se procede al grabado de las zonas expuestas del metal de Ia capa superior. Esto se lleva a cabo en un baño húmedo. Tras este grabado, se elimina Ia resina de las zonas protegidas mediante inmersión en un baño de acetona y se procede al lavado del resultado del proceso anterior en agua desionizada. Como se desprende de Ia figura 4, cabe destacar que el nivel metálico superior (3) contiene una serie de orificios que servirán posteriormente para definir los discos (5) del nivel metálico inferior (2), en una etapa de ataque seco en que el metal del nivel superior actuará como máscara.After the development, the exposed areas of the metal of the upper layer are etched. This is carried out in a wet bath. After this engraving, the resin is removed from the protected areas by immersion in an acetone bath and the result of the previous process is washed in deionized water. As can be seen from Figure 4, it should be noted that the upper metallic level (3) contains a series of holes that will subsequently serve to define the discs (5) of the lower metallic level (2), in a dry attack stage in which the Upper level metal will act as a mask.
La siguiente etapa consiste en una nueva pasivación, aunque en esta ocasión conviene que Ia capa depositada sea Io más fina posible sin menoscabo del aislamiento eléctrico de Ia capa metálica superior. Una vez pasivada Ia oblea, ésta se someterá a una nueva etapa fotolitográfica destinada a Ia definición de los discos (5) y los anillos (6).The next stage consists of a new passivation, although on this occasion it is convenient that the deposited layer be as thin as possible without damaging the electrical insulation of the upper metal layer. Once the wafer is passivated, it will be subjected to a new photolithographic stage destined to the definition of the disks (5) and the rings (6).
Tras cubrir el resultado del proceso anterior con una fina capa de fotoresina, esta se insola, a través de una máscara que contiene los motivos de los puntos de contacto con el nivel metálico inferior (2), así como unos discosAfter covering the result of the previous process with a thin layer of photoresin, it is insolated, through a mask that contains the motifs of the contact points with the lower metallic level (2), as well as some discs
(5) que definirán el tamaño de los anillos (6) del nivel metálico superior (2). Tras eliminar Ia resina no curada, se procede al ataque de Ia capa superior de oxinitruro, en una etapa de grabado que puede ser húmedo o seco. En esta etapa se consigue eliminar no sólo el dieléctrico del nivel superior, sino también el dieléctrico que separa los dos niveles metálicos en las zonas definidas como discos por el nivel metálico superior (2). Tras este grabado, se procede a Ia eliminación de Ia fotoresina en un baño de acetona. Tras esto, se realiza una limpieza del resultado final para eliminar restos de las etapas anteriores.(5) that will define the size of the rings (6) of the upper metal level (2). After removing the uncured resin, the upper layer of oxynitride is attacked, in an etching stage that can be wet or dry. In this stage it is possible to eliminate not only the dielectric of the upper level, but also the dielectric that separates the two metallic levels in the areas defined as disks by the upper metallic level (2). After this engraving, we proceed to Ia Elimination of the photoresin in an acetone bath. After this, a cleaning of the final result is performed to eliminate remains of the previous stages.
Ejemplo 2Example 2
Se describe un proceso para Ia fabricación, mediante técnicas fotolitográficas, de un dispositivo microelectrónico basado en redes de microelectrodos de disco y anillo.A process for the manufacture, by photolithographic techniques, of a microelectronic device based on disk and ring microelectrode networks is described.
A partir de una oblea de silicio (1 ) fig. 6.1 pulida se hizo crecer una capa de óxido de alrededor de una miera de espesor, una primera capa de material dieléctrico (4) tal y como se observa en Ia fig. 6.2. Esta capa de óxido sirve para aislar eléctricamente Ia oblea de silicio (1 ) del resto del dispositivo. A continuación, se llevó a cabo Ia metalización de Ia oblea de silicio (1 ) según muestra Ia fig. 6.3. En el caso que Ia presente invención esta metalización se realizó depositando una tricapa de titanio (20-50 nm), que actúa como promotor de adherencia bajo una capa de níquel (20-50 nm) que actúa como barrera difusional para evitar Ia mezcla del titanio con el oro que se deposita sobre el níquel. La capa de oro tiene un espesor comprendido, pero no limitado a, entre 50 y 200 nm.From a silicon wafer (1) fig. 6.1 polished an oxide layer of about one thick thickness was grown, a first layer of dielectric material (4) as seen in fig. 6.2. This oxide layer serves to electrically isolate the silicon wafer (1) from the rest of the device. Next, the metallization of the silicon wafer (1) was carried out as shown in fig. 6.3. In the case that the present invention, this metallization was carried out by depositing a titanium three-layer (20-50 nm), which acts as an adhesion promoter under a nickel layer (20-50 nm) that acts as a diffusion barrier to avoid the mixing of the titanium with gold that is deposited on nickel. The gold layer has a thickness, but not limited to, between 50 and 200 nm.
El siguiente paso consiste en una etapa de fotolitografía, tal y como se observa en fig. 6.4, que sirve para definir Ia geometría del nivel metálico donde quedarán definidos los discos (5) en el dispositivo final. Para ello, se depositó una capa de fotoresina sobre Ia oblea de silicio (1 ) metalizada y se insoló a través de una máscara con los motivos geométricos correspondientes, así como los motivos de alineamiento necesarios para Ia correcta definición de los siguientes niveles fotolitográficos.The next step consists of a photolithography stage, as seen in fig. 6.4, which serves to define the geometry of the metallic level where the disks (5) will be defined in the final device. For this, a layer of photoresin was deposited on the metallic silicon wafer (1) and insulated through a mask with the corresponding geometric patterns, as well as the alignment reasons necessary for the correct definition of the following photolithographic levels.
Una vez insolada, se reveló en un baño de disolvente capaz de eliminarOnce insolated, it was revealed in a solvent bath capable of removing
Ia resina no curada. El siguiente paso, según se detalla en Ia fig. 6.5, consistió en grabar, eliminando el metal de las zonas no protegidas por Ia fotoresina. Finalmente, se eliminó toda Ia resina en una etapa de decapado, y se procedió a limpiar de nuevo Ia el resultado obtenido mediante sucesivos lavados con agua desionizada.The uncured resin. The next step, as detailed in fig. 6.5, consisted of engraving, removing the metal from the areas not protected by the photoresin. Finally, all the resin was removed in a pickling stage, and the result obtained was again cleaned by successive washing with deionized water.
El siguiente paso, tal y como se observa en fig. 6.6, consistió en una etapa de pasivación con oxinitruro, generando una segunda capa de material dieléctrico (7). Dado que es el espesor de esta capa es el que controla Ia distancia efectiva entre el disco y el anillo, su espesor se puede hacer variar entre un mínimo de 0.5 mieras y un máximo de 2 mieras, fabricándose con un espesor de óxido de 1 miera. El óxido crece de forma isotrópica sobre toda Ia superficie.The next step, as seen in fig. 6.6, consisted of a passivation stage with oxynitride, generating a second layer of dielectric material (7). Since it is the thickness of this layer that controls the effective distance between the disk and the ring, its thickness can be varied between a minimum of 0.5 microns and a maximum of 2 microns, being manufactured with a thickness of oxide of 1 miera . The oxide grows isotropically over the entire surface.
A continuación, se llevó a cabo una nueva metalización, detallada en Ia fig. 6.7, del resultado obtenido del proceso anterior, utilizando para ello Ia tri- capa descrita anteriormente. En este nivel metálico superior (3) quedarán definidos los electrodos anulares que rodearán a los discos (5). Aunque en este caso el metal utilizado fue oro, es posible utilizar cualquier otro metal susceptible de ser depositado por sputtering, evaporación, electrodeposición, PVD o, en general, cualquier técnica compatible con procesos de sala blanca.Next, a new metallization was carried out, detailed in fig. 6.7, of the result obtained from the previous process, using the trilayer described above. In this upper metallic level (3) the annular electrodes that will surround the disks (5) will be defined. Although in this case the metal used was gold, it is possible to use any other metal that can be deposited by sputtering, evaporation, electrodeposition, PVD or, in general, any technique compatible with cleanroom processes.
La siguiente etapa consiste en Ia definición de las zonas en las que se conservará el segundo metal, mediante una etapa de fotolitografía según se detalla en Ia fig. 6.8. Para ello se cubrió el resultado obtenido del proceso anterior con una fina capa de fotoresina. A continuación, se insoló a través de una máscara de cromo en Ia que se han definido dichos motivos. Tras Ia exposición, se eliminó Ia resina no curada en un baño del disolvente correspondiente.The next stage consists in the definition of the zones in which the second metal will be preserved, by means of a photolithography stage as detailed in fig. 6.8. For this, the result obtained from the previous process was covered with a thin layer of photoresin. Then, it was insulated through a chrome mask in which said motifs have been defined. After exposure, the uncured resin was removed in a bath of the corresponding solvent.
Tras el revelado se procedió al grabado de las zonas expuestas del metal de Ia capa superior ver fig. 6.9. Esto se llevó a cabo en un baño húmedo. Tras este grabado, se eliminó Ia resina de las zonas protegidas mediante inmersión en un baño de acetona y se procedió al lavado del resultado obtenido en el proceso anterior en agua desionizada. La siguiente etapa consiste en una nueva pasivación tal y como se observa en Ia fig. 6.10, una tercera capa de material dieléctrico (8) aunque en esta ocasión conviene que Ia capa depositada sea Io más fina posible sin menoscabo del aislamiento eléctrico del nivel metálico inferior. Una vez pasivado, el resultado del proceso anterior se someterá a una nueva serie de etapas fotolitográficas tal y como se observa en Ia fig. 6.11 destinadas a Ia definición de los discos (5) y los anillos (6).After developing, the exposed areas of the metal of the upper layer were etched see fig. 6.9. This was carried out in a wet bath. After this etching, the resin was removed from the protected areas by immersion in an acetone bath and the result obtained in the previous process was washed in deionized water. The next stage consists of a new passivation as seen in fig. 6.10, a third layer of dielectric material (8) although on this occasion it is convenient that the deposited layer be as thin as possible without damaging the electrical insulation of the lower metallic level. Once passivated, the result of the previous process will be subjected to a new series of photolithographic stages, as observed in fig. 6.11 intended for the definition of disks (5) and rings (6).
Tras cubrir el resultado anterior con una fina capa de fotoresina, esta se insoló a través de una máscara que contenía los motivos de los discos (5) y los puntos de contacto con el nivel metálico inferior (2). Tras eliminar Ia resina no curada, se procedió al ataque de Ia capa superior de oxinitruro, en una etapa de grabado seco, tal y como se detalla en Ia fig. 6.12.After covering the previous result with a thin layer of photoresin, it was insulated through a mask containing the motifs of the discs (5) and the points of contact with the lower metallic level (2). After removing the uncured resin, the upper layer of oxynitride was attacked, in a dry etching stage, as detailed in fig. 6.12.
Seguidamente, se recoció Ia resina a 200° durante 30 minutos, y se procedió a un nuevo ataque seco para eliminar el oxinitruro de Ia capa intermedia, abriendo así los discos (5). Tras este grabado, se procedió a Ia eliminación de Ia fotoresina en un baño de acetona. Tras esto, se realizó una limpieza del resultado del proceso anterior para eliminar restos de las etapas anteriores como muestra Ia fig. 6.13.Then, the resin was annealed at 200 ° for 30 minutes, and a new dry attack was carried out to remove the oxynitride from the intermediate layer, thus opening the discs (5). After this engraving, the photoresin was removed in an acetone bath. After this, a cleaning of the result of the previous process was performed to eliminate remains of the previous stages as shown in fig. 6.13.
Definidos los discos (5) en el nivel metálico inferior (2), quedan por definir los anillos (6) sobre el nivel metálico superior (3).Once the discs (5) have been defined at the lower metallic level (2), the rings (6) on the upper metallic level (3) remain to be defined.
Esto se hizo mediante una nueva etapa fotolitográfica. Así, se depositó una nueva capa de fotoresina sobre Ia superficie y se insoló a través de una nueva máscara que incorpora los motivos de los anillos (6), así como de los puntos de conexión. Tras el revelado, se llevó a cabo una etapa de ataque seco para eliminar el oxinitruro de las zonas expuestas hasta Ia superficie del nivel superior de metal.This was done through a new photolithographic stage. Thus, a new layer of photoresin was deposited on the surface and insulated through a new mask that incorporates the motifs of the rings (6), as well as the connection points. After development, a dry attack stage was carried out to remove the oxynitride from the exposed areas to the surface of the top level metal.
Concluido el ataque, se eliminó Ia resina de las zonas protegidas mediante un baño de acetona y se limpió nuevamente el resultado final. After the attack, the resin was removed from the protected areas by an acetone bath and the final result was cleaned again.

Claims

R E I V I N D I C A C I O N E S
1. Dispositivo microelectrónico basado en redes de microelectrodos de disco (5) y anillo (6) caracterizado porque comprende:1. Microelectronic device based on networks of disk (5) and ring (6) microelectrodes characterized in that it comprises:
- una oblea de silicio (1 ),- a silicon wafer (1),
- al menos una primera capa de material dieléctrico (4) definida sobre Ia oblea de silicio (1 ),- at least a first layer of dielectric material (4) defined on the silicon wafer (1),
- un nivel metálico inferior (2) definido sobre Ia primera capa de material dieléctrico (4),- a lower metallic level (2) defined on the first layer of dielectric material (4),
- al menos una segunda capa de material dieléctrico (7) definida sobre el nivel metálico inferior (2),- at least a second layer of dielectric material (7) defined on the lower metallic level (2),
- un nivel metálico superior (3) definido sobre Ia segunda capa de material dieléctrico (7), - al menos un disco (5) definido sobre el nivel metálico inferior (2), y- an upper metallic level (3) defined on the second layer of dielectric material (7), - at least one disk (5) defined on the lower metallic level (2), and
- al menos un anillo (6) definido sobre el nivel metálico superior (3).- at least one ring (6) defined on the upper metallic level (3).
2. Dispositivo según reivindicación 1 caracterizado porque adicionalmente comprende al menos una tercera capa de material dieléctrico (8) definida sobre el nivel metálico superior (3).2. Device according to claim 1 characterized in that it additionally comprises at least a third layer of dielectric material (8) defined on the upper metal level (3).
3. Método de fabricación del dispositivo microelectrónico basado en redes de microelectrodos de disco (5) y anillo (6) descrito en Ia reivindicación 1 ó 2 caracterizado porque comprende las siguientes fases:3. Method of manufacturing the microelectronic device based on networks of disk (5) and ring (6) microelectrodes described in claim 1 or 2 characterized in that it comprises the following phases:
• deposición de una capa de material dieléctrico (4) sobre una oblea de silicio (1 ), de tal forma que material que Ia forma quede aislado con un espesor mínimo de 0.6 micrómetros,• deposition of a layer of dielectric material (4) on a silicon wafer (1), so that the material is insulated with a minimum thickness of 0.6 micrometers,
• una primera metalización sobre Ia primera capa de material dieléctrico (4) mediante Ia deposición de un metal creando el nivel metálico inferior (2) donde se formarán los discos (5), • primera fotolitografía para definir Ia geometría de los discos (5) del nivel metálico inferior (2), • deposición de una segunda capa de material dieléctrico (7) con propiedades de aislamiento eléctrico sobre el nivel metálico inferior (2),• a first metallization on the first layer of dielectric material (4) by means of the deposition of a metal creating the lower metallic level (2) where the disks (5) will be formed, • first photolithography to define the geometry of the disks (5) of the lower metallic level (2), • deposition of a second layer of dielectric material (7) with electrical insulation properties on the lower metallic level (2),
• una segunda metalización en Ia que se deposita el nivel metálico superior (3) que servirá para definir los anillos (6) y que a su vez actúa como máscara para definir posteriormente los discos (5) en el nivel metálico inferior (2),• a second metallization in which the upper metallic level (3) is deposited that will serve to define the rings (6) and which in turn acts as a mask to subsequently define the discs (5) in the lower metallic level (2),
• segunda fotolitografía para definir Ia geometría de las zonas en que se alojarán los anillos (6) del nivel metálico superior (3),• second photolithography to define the geometry of the areas where the rings (6) of the upper metal level (3) will be housed,
• deposición de una tercera capa de material dieléctrico (8) que será Io más delgada posible, para mantener aislado eléctricamente del medio al segundo metal ,y• deposition of a third layer of dielectric material (8) that will be as thin as possible, to keep the second metal electrically isolated, and
• definición de los discos (5) situados en nivel metálico inferior (2), definición de los anillos (6) en el nivel metálico superior (2) y definición de los contactos correspondientes. • definition of the disks (5) located at the lower metallic level (2), definition of the rings (6) at the upper metallic level (2) and definition of the corresponding contacts.
4. Método de fabricación del dispositivo microelectrónico basado en redes de microelectrodos de disco (5) y anillo (6) según reivindicación 2 caracterizado porque Ia primera fotolitografía comprende:4. Method of manufacturing the microelectronic device based on networks of disk (5) and ring (6) microelectrodes according to claim 2 characterized in that the first photolithography comprises:
• una insolación a través de una máscara con los motivos geométricos correspondientes, así como los motivos de alineamiento necesarios para Ia correcta definición de los siguientes niveles fotolitográficos,• an insolation through a mask with the corresponding geometric motifs, as well as the alignment motifs necessary for the correct definition of the following photolithographic levels,
• un revelado en un baño de disolvente,• a development in a solvent bath,
• un grabado del metal consistente en un ataque redox en un baño de yodo/yoduro de las zonas no protegidas por Ia fotoresina, a fin de eliminar el metal de las zonas no protegidas, • un decapado con acetona para eliminar toda Ia resina o mediante exposición a un plasma de oxígeno, y• an engraving of the metal consisting of a redox attack in an iodine / iodide bath of the areas not protected by the photoresin, in order to remove the metal from the unprotected areas, • a pickling with acetone to remove all the resin or by exposure to an oxygen plasma, and
• limpiado del resultado obtenido en el proceso anterior, mediante sucesivos lavados con agua desionizada. • cleaning of the result obtained in the previous process, by successive washing with deionized water.
5. Método de fabricación del dispositivo microelectrónico basado en redes de microelectrodos de disco (5) y anillo (6) según reivindicación 2 caracterizado porque Ia segunda fotolitografía comprende:5. Method of manufacturing the microelectronic device based on networks of disk (5) and ring (6) microelectrodes according to claim 2 characterized in that the second photolithography comprises:
• un ataque húmedo del metal, • un recocido de Ia resina, y• a wet attack of the metal, • an annealing of the resin, and
• un ataque de Ia capa de dieléctrico que separa ambos metales.• an attack of the dielectric layer that separates both metals.
6. Método de fabricación del dispositivo microelectrónico basado en redes de microelectrodos de disco (5) y anillo (6) según reivindicación 2 caracterizado porque Ia definición de los discos (5) comprende:6. Method of manufacturing the microelectronic device based on networks of disk (5) and ring (6) microelectrodes according to claim 2 characterized in that the definition of the disks (5) comprises:
• una insolación a través de una máscara de cromo o una transparencia en Ia que se han definido discos (5) cuyo diámetro coincide con el diámetro exterior de los anillos (6) situados en el nivel metálico inferior (2), - un revelado en un baño de disolvente,• an insolation through a chrome mask or a transparency in which discs (5) have been defined whose diameter coincides with the outer diameter of the rings (6) located in the lower metallic level (2), - a development in a solvent bath,
• un recocido de Ia resina,• an annealing of the resin,
• un grabado seco de Ia tercera capa de material dieléctrico (8) que no se detendrá hasta que el nivel metálico inferior (2) quede expuesto al ambiente, - eliminación de Ia resina de las zonas protegidas del resultado obtenido en el proceso anterior en un baño de acetona, y• a dry etching of the third layer of dielectric material (8) that will not stop until the lower metallic level (2) is exposed to the environment, - removal of the resin from the protected areas of the result obtained in the previous process in a acetone bath, and
• limpieza del resultado final mediante sucesivos lavados con agua desionizada. • cleaning of the final result by successive washing with deionized water.
PCT/ES2009/070477 2008-11-11 2009-10-29 Microelectronic device based on grids of disc and ring microelectrodes, and method for producing said device WO2010055182A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5389215A (en) * 1992-11-05 1995-02-14 Nippon Telegraph And Telephone Corporation Electrochemical detection method and apparatus therefor
US20080128265A1 (en) * 2006-11-30 2008-06-05 Imperial Innovations Limited Electrode Assembly and System

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5389215A (en) * 1992-11-05 1995-02-14 Nippon Telegraph And Telephone Corporation Electrochemical detection method and apparatus therefor
US20080128265A1 (en) * 2006-11-30 2008-06-05 Imperial Innovations Limited Electrode Assembly and System

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