CA1326155C - High resolution e-beam lithographic technique - Google Patents
High resolution e-beam lithographic techniqueInfo
- Publication number
- CA1326155C CA1326155C CA000556672A CA556672A CA1326155C CA 1326155 C CA1326155 C CA 1326155C CA 000556672 A CA000556672 A CA 000556672A CA 556672 A CA556672 A CA 556672A CA 1326155 C CA1326155 C CA 1326155C
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- Prior art keywords
- imaging layer
- layer
- imaging
- recited
- pattern
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
- G03F7/095—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers having more than one photosensitive layer
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
- Y10S430/143—Electron beam
Abstract
Abstract A method of reproducing sub-micron images in a first imaging layer. A second imaging layer is deposited on an etch-stop film formed on the first layer, and the second imaging layer is exposed to an E-beam at low dose. The resulting standing wave exposure pattern is converted into a corresponding topology pattern having peaks and valleys by exposure to a wet developer. Ions are implanted through the second imaging layer into portions of the first imaging layer below the valley portions of the standing wave topology pattern. The second imaging layer is removed without appreciably attacking the etch-stop layer, and then the etch stop layer is removed without appreciably attacking the first imaging layer.
The first imaging layer is anisotropically etched in an O2 RIE, the implanted regions serving as an etch mask. The process results in the formation of small images at high throughput.
The first imaging layer is anisotropically etched in an O2 RIE, the implanted regions serving as an etch mask. The process results in the formation of small images at high throughput.
Description
"- 1326155 HIGH RESOLUTION E-BEAM LITHOGRAPHIC TECHNIQUE
Background of the Invention Optical exposure systems are the current S technology of choice for patterning photosensitive polymers in manufacturing applications. However, in the sub-micron world that looms on the horizon, - exotic photoresist compositions and complex processing techniques will become increasingly necessary in order to prolong the viability of ~ optical exposure systems. Accordingly, alternate - photoresist exposure systems are being explored in the hope that they will fulfill the stringent manufacturing requirements of tomorrow's technology.
` One particularly promising technology is electron beam (E-beam) exposure. In these systems, beams of electrons are irradiated on a ~` surface to be patterned. In a particular ` 20 application referred to as ~direct-write E-beam exposure,~ these electron beams are controlled by an imposed electric field to expose selected areas of a photoresist layer, rather than exposing selected areas of the photoresist through a ~' 25 metallic mask as in conventional optical exposure systems. Since these metallic masks are costly to ~ ` design and produce, the combined advantages of - printing images at tighter geometries and elimin-ating metallic ma5ks make direct-write E-beam systems very attractive.
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132615~
Background of the Invention Optical exposure systems are the current S technology of choice for patterning photosensitive polymers in manufacturing applications. However, in the sub-micron world that looms on the horizon, - exotic photoresist compositions and complex processing techniques will become increasingly necessary in order to prolong the viability of ~ optical exposure systems. Accordingly, alternate - photoresist exposure systems are being explored in the hope that they will fulfill the stringent manufacturing requirements of tomorrow's technology.
` One particularly promising technology is electron beam (E-beam) exposure. In these systems, beams of electrons are irradiated on a ~` surface to be patterned. In a particular ` 20 application referred to as ~direct-write E-beam exposure,~ these electron beams are controlled by an imposed electric field to expose selected areas of a photoresist layer, rather than exposing selected areas of the photoresist through a ~' 25 metallic mask as in conventional optical exposure systems. Since these metallic masks are costly to ~ ` design and produce, the combined advantages of - printing images at tighter geometries and elimin-ating metallic ma5ks make direct-write E-beam systems very attractive.
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132615~
An article by Kenty et al, entitled "Electron Beam Fabrication of High Resolution MasXs, n J, Vac. Sci. Tech., October-December 1983, pp.
1211-1214 discusses a particular patterning method S for E-beam exposed resists. A quartz plate coated with polymethyl methacrylate (PMMA) was exposed to a direct-write electron beam at 20 kev in order to ~ form 0.5 m features upon wet development. The `` resist pattern was then ion implanted with silicon, and the resulting mask was found to work well as a photomask for optically exposing othèr photoresist materials. See also an article by Maclver, entitled ~igh Resolution Photomasks with Ion-Bom-barded Polymethyl Methacrylate Nasking Medium, n J, Electrochem Soc.: Solid-State Sci. & Tech., April 1982 pp. 827-830.
In an article by Iida et al, entitled ~An Approach to Quarter-Micron E-Beam Lithography Using Optimi~ed Double Layer Resist Process, n IEDM
Digest of Technical Papèrs 1983, Paper 25.6, pp.
562-565, an E-beam is-used in a direct write mode `` i to pattern an upper thin layer of photoresist.
$he patterned photoresist is in turn used to pattern an underlaying thicker polyimide layer in an 2 plasma. As shown in Fig. 2 of the paper, by patterning only the upper 0.4 ~m photoresist layer ; by direct-write E-beam techniques7 a 20 kev accel-eration ~oltage produces better results than ` patterning a single, 1.8 ~m photoresist layer at a 120 kev acceleration voltage.
In an article by Ishii et al, entitled "A New Electron Beam Patterning Technology for 0.2 ~m VLSI,~ 1985 VLSI Symposium, May 14-16 1985, Kobe, Japan, paper VIII-l, pp. 70-71, a direct-write E-beam system (acceleration voltage of 30 kev) is used to partially expose and pattern a photoresist layer. That is, only the upper portion of the photoresist layer is patterned. Then a second layer is deposited on the photoresist layer. The second layer is etched bac~ so that portions of the second layer remain in the pattern that was formed in the photoresist. Finally, the photoresist is etched under conditions tha~ do not etch the remaining portions of the second layer, so that the exposed portions of the photoresist are removed. A silicon resin was used as the ; second layer and PMMA was used as the photoresist.
Note that in order to adequately define the final pattern, the etchback o~ the second layer had to be continued until at least half of the patterned portion of the photoresist layer was removed.
.
Both of the above Iida and Ishii articles are directed to the same general idea. In order to completely pattern si`n~le photoresist layers of a thickness of 1 ~m or greater, the acceleration voltage must be kept at a high level and the photoresist must be exposed to the E-beam for a ` 25 longer period of time lin other words, the E-beam ~dose~ necessary to pattern a conventional photoresist làyer is high). As the dose increases, the throughput of the exposure tool decreases. Thus, others such as Iida and Ishii have attempted to decrease the necessary dose (to ` decrease dwell time and hence increase throughput) by totally patterning a thin layer (Iida) or by partially pa-terning a thick layer (Ishii).
Accordingly, there is a need to formulate other processes that increase the throughput of direct-write E-beam exposure systems.
Summary of the Invention It is thus an object of the present invention to increase the throughput of direct-write E-beam `
systems~
It is another object of the invention to formulate a simple E-beam exposure process.
It is yet another object of the invention to provide an E-beam exposure process that reliably prints sub-micron images at high throughput.
.
The above and other objects of the invention `~` are realized by a method of forming small images in a first imaging lay~r arranged on a substrate, comprising the steps of forming a second imaging layer on the first imaging layer; exposing the second imaging layer under conditions such that an exposure pattern is formed only in an upper - 20 portion of the second imaging layer; developing ` the second imaging layer to convert the exposure pattern into a topology pattern in the upper portion of the second imaging~ layer; implanting ions through the second imaging layer into por-tions of the first imaging layer, as a function of the topology pattern in the second imaging layer;
removing the second imaging layer; and etching the first imaging layer under conditions that do not ` appreciably attack implanted portions thereof, so as to form a pattern in the first imaging layer.
~ 1326155 Because a low E-beam dose is sufficient to form the exposure pattern in the second imaging layer, a high throughput can be realized.
Brief Description of the Drawing The above and other teachings of the present invention will become more apparent upon a detailed description of the best mode for carrying out the invention as rendered below. ln the description to follow, reference will be made to the accompany-` ~ 10 ing Drawing, in which:
, .
Fig. 1 is a cross-sectional view of a sub-~ strate having the two imaging layers formed thereon:
. ~ .
Fig. 2 is a cross-sectional view of a sub-strate having the two imaging layers, in which the upper layer is particularly patterned:
`~ Fig. 3 is a cross-sectional view of a sub-~trate having ions implanted into the upper and lower imaging layers;
`~ 20 Fig. 4 is a cross-sectional view of a sub-strate having the upper imaging layer removed; and -.
Fig. 5 is a cross-sectional view of a sub-strate having the lower imaging layer patterned so as to define small images.
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. . .
` 1326155 Best Mode for Carrying out the Invention With reference to Fig. 1, two imaging layers 10 and 30 are disposed on a substrate 1~ The substrate 1 is depicted as a unitary st-ucture for the purpose of more clearly illustrating the invention. In practice substrate 1 could be comprised of a silicon or gallium arsenide wafer that may have one or more layers disposed on it to be patterned by use of the lithographic process of the invention. Imaging layer 30 can be made of any positive-acting material that can be patterned by an electron beam, e.g. polymethyl methacylate, or ~PNNA. n Imaging layer 10 can be made of any material in which silicon ions have a diffusion coefficient that is within the range of the diffusion coe~ficient in imaging layer 30. A
conventional photos~nsitive polymer or other organic resin such as one of the ~AZ~ series of photosensitive novolac resins sold by the AZ
Photoresist Products Group of American Hoechst Corp. of Somerville, NJ (~AZ" is a trademark of American Hoechst Corp.) would meet the above criterion. Both imaging layers 10 and 30 can be formed on substrate 1 by spin-application to the desired thickness ~typically 0.5 microns + 0.2 microns). Note that the imaging layer 30 should not be appreciably thicker than imaging layer 10.
The layers can be of substantially equal thickness as shown in Fig. 1, vr the imaging layer 30 can be thinner than imaging layer 10.
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A layer of silicon oxide 20 is disposed between photoresist layers 10 and 30. The purpose of this silicon oxide layer 20 is to insure that photoresist layer 30 can be stripped withol~t removing photoresist layer 10. The thickness of this silicon oxide layer should be on the order of several hundred Angstroms. The etch-stop function of silicon oxide layér 20 will be described in more detail below.
As shown in Fig. 2, the upper imaging layer 30 is then exposed to a direct-write E-beam that defines a standing wave pattern in an upper portion 30A of layer 30. The E-beam acceleration energy should be on the order of 20-30 kev. At this acceleration energy and low dose, the throughput of the exposure system is high. As shown in the Iida et al article, these .
acceleration energies `will result in a standing wave exposure pattern being formed in the upper surface of the exposed imaging layer 30. Imaging layer 30 is then exposed to a wet developer (e.g.
IPA) that selectively removes the exposed portions 30A without removing the bulk film. The resulting standing wave topology pattern 35 may define a sub-0.5 ~m space peak-to-peak.
Then, as shown in Fig. 3 f ions are implanted through the upper imaging layer 30 to form implant-ed pits lOA in the lower imaging layer 10 as defined by the topology pattern 35. The implant energy/dose is a function of the thickness of imaging layer 30 as well as the diffusion coeffic-ient of the particular ion specie through the ~;~
-~ 1 326 1 55 particular imaging layer composition. The peak ion concentration should be at a point above the upper surface of imaging layer 10, such that the implanted pattern is centered about the interface between imaging layers 10 and 30. Note that the ions will penetrate through silicon oxide layer 20 without appreciably distorting the ion implant pattern. In this manner, only those portions of layer beneath the valleys defined by topology pattern 35 will be implanted with ions. The particular ion specie selected should provide a sufficiently high etch rate ratio between implanted and non-implanted portions of imaging layer 10, e.g. silicon or oxygen. ~he shape of tbe implanted pits 10~ as well as the spacing between pits can also be controlled as a function of the implant energy Itypically on the order of 100 kev).
Then, the upper imaging layer 30 is removed ; 20 in an etchant that does not appreciably remove the silicon oxide layer 20. Such an etchant could be a solvent such as n-methyl pyrrollidone tNMP) or a dry etch such as an oxygen-based reactive ion etch ~ ~RIE). The dry etchant is preferable because it `~ 25 is more compatible with the subsequent processing described below.
Then, the silicon oxide layer 20 is removed without appreciably removing the upper surface of :3 ` ` the imaging layer 10. This is done by exposing the~ silicon oxidè layer to a plasma etch in a CF4-O2 gas combination, wherein the oxygen content is low (e.g., less than 25% of the total gas mixture by volume). At this low oxygen concentra-tion, both the implanted pits lOA and the non-~` 1326155 implanted portions of photoresist 10 will etch more slowly than the silicon oxide layer 20.
While it is possible that the implanted pits lOA
may be etched at a somewhat faster rate than the bulk photoresist 10, the overall etch rate differ-ence between these materials and the silicon oxide layer 10 should dominate. The resulting structure is shown in Fig~ 4~
Then, as shown in Fig~ 5, the lower imaging layer 10 is treated in an anisotropic etchant that is highly selective be~ween the bulk film 10 and the implanted pits lOA. For example, if the ; implanted specie was silicon, an oxygen-based RIE
will anisotropically etch the exposed portions of ; 15 imaging layer 10 without appreciably etching the pits lOA~
The resulting pattern can then be used to etch or define an ion implant with respect to the - substrate 1 having none, one, or more layers thereon to be pro5essed~ Note that the pattern is formed by a process that utilizes a low E-beam ` dose, improving throughput. At the same time, due to its use of highly controllable implantation techniques, the process Qf the invention retains the narrow dimensions and other advantages presented by direct write E-beam isYstems.
~`~ Various modifications can be made to the invention as described above. For example, the silicon oxide layer 20 could be deleted~ With the oxide layer removed, the upper photoresist layer 30 would be stripped in an 2 plasma. The etch would have to be monitored so that it is terminated before an excessive amount of the underlaying photoresist layer 10 is removed.
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~ 1326155 Silicon oxide layer 20 could be constituted from another material, such as silicon nitride or silicon oxynitride, or it could be constituted by layers of different materials, such as a lower layer of silicon nitride and an upper layer of silicon oxide.
It is to be understood that the above teach-ings are not limitative to the invention per se.
That is, various other modifications can be made to the best mode for carrying out the invention as described above without departing from the spirit and scope of the invention~
~ . .
;~
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1211-1214 discusses a particular patterning method S for E-beam exposed resists. A quartz plate coated with polymethyl methacrylate (PMMA) was exposed to a direct-write electron beam at 20 kev in order to ~ form 0.5 m features upon wet development. The `` resist pattern was then ion implanted with silicon, and the resulting mask was found to work well as a photomask for optically exposing othèr photoresist materials. See also an article by Maclver, entitled ~igh Resolution Photomasks with Ion-Bom-barded Polymethyl Methacrylate Nasking Medium, n J, Electrochem Soc.: Solid-State Sci. & Tech., April 1982 pp. 827-830.
In an article by Iida et al, entitled ~An Approach to Quarter-Micron E-Beam Lithography Using Optimi~ed Double Layer Resist Process, n IEDM
Digest of Technical Papèrs 1983, Paper 25.6, pp.
562-565, an E-beam is-used in a direct write mode `` i to pattern an upper thin layer of photoresist.
$he patterned photoresist is in turn used to pattern an underlaying thicker polyimide layer in an 2 plasma. As shown in Fig. 2 of the paper, by patterning only the upper 0.4 ~m photoresist layer ; by direct-write E-beam techniques7 a 20 kev accel-eration ~oltage produces better results than ` patterning a single, 1.8 ~m photoresist layer at a 120 kev acceleration voltage.
In an article by Ishii et al, entitled "A New Electron Beam Patterning Technology for 0.2 ~m VLSI,~ 1985 VLSI Symposium, May 14-16 1985, Kobe, Japan, paper VIII-l, pp. 70-71, a direct-write E-beam system (acceleration voltage of 30 kev) is used to partially expose and pattern a photoresist layer. That is, only the upper portion of the photoresist layer is patterned. Then a second layer is deposited on the photoresist layer. The second layer is etched bac~ so that portions of the second layer remain in the pattern that was formed in the photoresist. Finally, the photoresist is etched under conditions tha~ do not etch the remaining portions of the second layer, so that the exposed portions of the photoresist are removed. A silicon resin was used as the ; second layer and PMMA was used as the photoresist.
Note that in order to adequately define the final pattern, the etchback o~ the second layer had to be continued until at least half of the patterned portion of the photoresist layer was removed.
.
Both of the above Iida and Ishii articles are directed to the same general idea. In order to completely pattern si`n~le photoresist layers of a thickness of 1 ~m or greater, the acceleration voltage must be kept at a high level and the photoresist must be exposed to the E-beam for a ` 25 longer period of time lin other words, the E-beam ~dose~ necessary to pattern a conventional photoresist làyer is high). As the dose increases, the throughput of the exposure tool decreases. Thus, others such as Iida and Ishii have attempted to decrease the necessary dose (to ` decrease dwell time and hence increase throughput) by totally patterning a thin layer (Iida) or by partially pa-terning a thick layer (Ishii).
Accordingly, there is a need to formulate other processes that increase the throughput of direct-write E-beam exposure systems.
Summary of the Invention It is thus an object of the present invention to increase the throughput of direct-write E-beam `
systems~
It is another object of the invention to formulate a simple E-beam exposure process.
It is yet another object of the invention to provide an E-beam exposure process that reliably prints sub-micron images at high throughput.
.
The above and other objects of the invention `~` are realized by a method of forming small images in a first imaging lay~r arranged on a substrate, comprising the steps of forming a second imaging layer on the first imaging layer; exposing the second imaging layer under conditions such that an exposure pattern is formed only in an upper - 20 portion of the second imaging layer; developing ` the second imaging layer to convert the exposure pattern into a topology pattern in the upper portion of the second imaging~ layer; implanting ions through the second imaging layer into por-tions of the first imaging layer, as a function of the topology pattern in the second imaging layer;
removing the second imaging layer; and etching the first imaging layer under conditions that do not ` appreciably attack implanted portions thereof, so as to form a pattern in the first imaging layer.
~ 1326155 Because a low E-beam dose is sufficient to form the exposure pattern in the second imaging layer, a high throughput can be realized.
Brief Description of the Drawing The above and other teachings of the present invention will become more apparent upon a detailed description of the best mode for carrying out the invention as rendered below. ln the description to follow, reference will be made to the accompany-` ~ 10 ing Drawing, in which:
, .
Fig. 1 is a cross-sectional view of a sub-~ strate having the two imaging layers formed thereon:
. ~ .
Fig. 2 is a cross-sectional view of a sub-strate having the two imaging layers, in which the upper layer is particularly patterned:
`~ Fig. 3 is a cross-sectional view of a sub-~trate having ions implanted into the upper and lower imaging layers;
`~ 20 Fig. 4 is a cross-sectional view of a sub-strate having the upper imaging layer removed; and -.
Fig. 5 is a cross-sectional view of a sub-strate having the lower imaging layer patterned so as to define small images.
. .
. . .
` 1326155 Best Mode for Carrying out the Invention With reference to Fig. 1, two imaging layers 10 and 30 are disposed on a substrate 1~ The substrate 1 is depicted as a unitary st-ucture for the purpose of more clearly illustrating the invention. In practice substrate 1 could be comprised of a silicon or gallium arsenide wafer that may have one or more layers disposed on it to be patterned by use of the lithographic process of the invention. Imaging layer 30 can be made of any positive-acting material that can be patterned by an electron beam, e.g. polymethyl methacylate, or ~PNNA. n Imaging layer 10 can be made of any material in which silicon ions have a diffusion coefficient that is within the range of the diffusion coe~ficient in imaging layer 30. A
conventional photos~nsitive polymer or other organic resin such as one of the ~AZ~ series of photosensitive novolac resins sold by the AZ
Photoresist Products Group of American Hoechst Corp. of Somerville, NJ (~AZ" is a trademark of American Hoechst Corp.) would meet the above criterion. Both imaging layers 10 and 30 can be formed on substrate 1 by spin-application to the desired thickness ~typically 0.5 microns + 0.2 microns). Note that the imaging layer 30 should not be appreciably thicker than imaging layer 10.
The layers can be of substantially equal thickness as shown in Fig. 1, vr the imaging layer 30 can be thinner than imaging layer 10.
:i ~U9-86-012 ~ .
., ,~
A layer of silicon oxide 20 is disposed between photoresist layers 10 and 30. The purpose of this silicon oxide layer 20 is to insure that photoresist layer 30 can be stripped withol~t removing photoresist layer 10. The thickness of this silicon oxide layer should be on the order of several hundred Angstroms. The etch-stop function of silicon oxide layér 20 will be described in more detail below.
As shown in Fig. 2, the upper imaging layer 30 is then exposed to a direct-write E-beam that defines a standing wave pattern in an upper portion 30A of layer 30. The E-beam acceleration energy should be on the order of 20-30 kev. At this acceleration energy and low dose, the throughput of the exposure system is high. As shown in the Iida et al article, these .
acceleration energies `will result in a standing wave exposure pattern being formed in the upper surface of the exposed imaging layer 30. Imaging layer 30 is then exposed to a wet developer (e.g.
IPA) that selectively removes the exposed portions 30A without removing the bulk film. The resulting standing wave topology pattern 35 may define a sub-0.5 ~m space peak-to-peak.
Then, as shown in Fig. 3 f ions are implanted through the upper imaging layer 30 to form implant-ed pits lOA in the lower imaging layer 10 as defined by the topology pattern 35. The implant energy/dose is a function of the thickness of imaging layer 30 as well as the diffusion coeffic-ient of the particular ion specie through the ~;~
-~ 1 326 1 55 particular imaging layer composition. The peak ion concentration should be at a point above the upper surface of imaging layer 10, such that the implanted pattern is centered about the interface between imaging layers 10 and 30. Note that the ions will penetrate through silicon oxide layer 20 without appreciably distorting the ion implant pattern. In this manner, only those portions of layer beneath the valleys defined by topology pattern 35 will be implanted with ions. The particular ion specie selected should provide a sufficiently high etch rate ratio between implanted and non-implanted portions of imaging layer 10, e.g. silicon or oxygen. ~he shape of tbe implanted pits 10~ as well as the spacing between pits can also be controlled as a function of the implant energy Itypically on the order of 100 kev).
Then, the upper imaging layer 30 is removed ; 20 in an etchant that does not appreciably remove the silicon oxide layer 20. Such an etchant could be a solvent such as n-methyl pyrrollidone tNMP) or a dry etch such as an oxygen-based reactive ion etch ~ ~RIE). The dry etchant is preferable because it `~ 25 is more compatible with the subsequent processing described below.
Then, the silicon oxide layer 20 is removed without appreciably removing the upper surface of :3 ` ` the imaging layer 10. This is done by exposing the~ silicon oxidè layer to a plasma etch in a CF4-O2 gas combination, wherein the oxygen content is low (e.g., less than 25% of the total gas mixture by volume). At this low oxygen concentra-tion, both the implanted pits lOA and the non-~` 1326155 implanted portions of photoresist 10 will etch more slowly than the silicon oxide layer 20.
While it is possible that the implanted pits lOA
may be etched at a somewhat faster rate than the bulk photoresist 10, the overall etch rate differ-ence between these materials and the silicon oxide layer 10 should dominate. The resulting structure is shown in Fig~ 4~
Then, as shown in Fig~ 5, the lower imaging layer 10 is treated in an anisotropic etchant that is highly selective be~ween the bulk film 10 and the implanted pits lOA. For example, if the ; implanted specie was silicon, an oxygen-based RIE
will anisotropically etch the exposed portions of ; 15 imaging layer 10 without appreciably etching the pits lOA~
The resulting pattern can then be used to etch or define an ion implant with respect to the - substrate 1 having none, one, or more layers thereon to be pro5essed~ Note that the pattern is formed by a process that utilizes a low E-beam ` dose, improving throughput. At the same time, due to its use of highly controllable implantation techniques, the process Qf the invention retains the narrow dimensions and other advantages presented by direct write E-beam isYstems.
~`~ Various modifications can be made to the invention as described above. For example, the silicon oxide layer 20 could be deleted~ With the oxide layer removed, the upper photoresist layer 30 would be stripped in an 2 plasma. The etch would have to be monitored so that it is terminated before an excessive amount of the underlaying photoresist layer 10 is removed.
:- , . .;
; ., , ." . , , ~ ,, ~ ",~
~ 1326155 Silicon oxide layer 20 could be constituted from another material, such as silicon nitride or silicon oxynitride, or it could be constituted by layers of different materials, such as a lower layer of silicon nitride and an upper layer of silicon oxide.
It is to be understood that the above teach-ings are not limitative to the invention per se.
That is, various other modifications can be made to the best mode for carrying out the invention as described above without departing from the spirit and scope of the invention~
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Claims (13)
1. A method of forming sub-micron images in a first imaging layer disposed on a substrate having one or more layers thereon, comprising of steps of:
depositing a second imaging layer over said first imaging layer;
exposing said second imaging layer to an E-beam under conditions such that a standing wave exposure pattern is formed only in an upper portion of said second imaging layer;
developing said second imaging layer to convert said exposure pattern into a standing wave topology pattern in said upper portion of said second imaging layer;
implanting ions through said second imaging layer into portions of said first imaging layer as defined by said standing wave topology pattern, to form implanted pits in said first imaging layer;
removing said second imaging layer without appreciably removing said first imaging layer; and anisotropically etching said first imaging layer in a etchant that does not appreciably attack said implanted pits of said first imaging layer.
depositing a second imaging layer over said first imaging layer;
exposing said second imaging layer to an E-beam under conditions such that a standing wave exposure pattern is formed only in an upper portion of said second imaging layer;
developing said second imaging layer to convert said exposure pattern into a standing wave topology pattern in said upper portion of said second imaging layer;
implanting ions through said second imaging layer into portions of said first imaging layer as defined by said standing wave topology pattern, to form implanted pits in said first imaging layer;
removing said second imaging layer without appreciably removing said first imaging layer; and anisotropically etching said first imaging layer in a etchant that does not appreciably attack said implanted pits of said first imaging layer.
2. The method as recited in claim 1, wherein said first imaging layer is comprised of a photosensitive novolac resin material, and wherein said second imaging layer is comprised of a resinous material that can be patterned by an electron beam.
3. The method as recited in claim 1, wherein said standing wave topology pattern has an upper half and a lower half.
4. The method as recited in claim 3, wherein portions of said first imaging layer beneath said lower half of said standing wave tolopogy pattern in said second imaging layer receive said ions implanted through said second imaging layer to form said implanted pits.
5. The method as recited in claim 4, wherein said ions comprise silicon ions.
6. The method as recited in claim 4, wherein said ions comprise oxygen ions.
7. The method as recited in claim 4, wherein said first imaging layer is anisotropically etched by exposure to an O2 RIE.
8. A method of forming sub-micron images in a first imaging layer arranged on a substrate having one or more layers thereon, comprising the steps of:
depositing a thin etch-stop layer on said first imaging layer;
depositing a second imaging layer on said etch-stop layer;
exposing said second imaging layer to an E-beam, so as to form a standing wave exposure pattern in an upper portion of said second imaging layer;
developing said second imaging layer to convert said standing wave exposure pattern into a standing wave topology pattern having peaks and valleys therein;
implanting silicon ions through said second imaging layer and said etch-stop layer into portions of said first imaging layer beneath said valleys of said standing wave topology pattern in said second imaging layer;
removing said second imaging layer in an etchant that does not appreciably attack said etch-stop layer;
removing said etch-stop layer in an etchant that does not appreciably attack said first imaging layer; and anisotropically etching portions of said first imaging layer between said implanted portions of said first imaging layer.
depositing a thin etch-stop layer on said first imaging layer;
depositing a second imaging layer on said etch-stop layer;
exposing said second imaging layer to an E-beam, so as to form a standing wave exposure pattern in an upper portion of said second imaging layer;
developing said second imaging layer to convert said standing wave exposure pattern into a standing wave topology pattern having peaks and valleys therein;
implanting silicon ions through said second imaging layer and said etch-stop layer into portions of said first imaging layer beneath said valleys of said standing wave topology pattern in said second imaging layer;
removing said second imaging layer in an etchant that does not appreciably attack said etch-stop layer;
removing said etch-stop layer in an etchant that does not appreciably attack said first imaging layer; and anisotropically etching portions of said first imaging layer between said implanted portions of said first imaging layer.
9. The method as recited in claim 8, wherein said first imaging layer is comprised of a novolak-based photo-sensitive resin, and wherein said second imaging layer is comprised of PMMA.
10. The method as recited in claim 8, wherein said etch-stop layer is comprised of silicon oxide.
11. The method as recited in claim 8, wherein said second imaging layer is removed by exposure to an O2 plasma.
12. The method as recited in claim 11, wherein said eth-stop layer is removed by exposure to a CF4+O2 plasma.
13. The method as recited in claim 12, wherein said first imaging layer is anisotropically etched by exposure to an O2 RIE.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/029,110 US4772539A (en) | 1987-03-23 | 1987-03-23 | High resolution E-beam lithographic technique |
| US029,110 | 1987-03-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1326155C true CA1326155C (en) | 1994-01-18 |
Family
ID=21847283
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556672A Expired - Fee Related CA1326155C (en) | 1987-03-23 | 1988-01-15 | High resolution e-beam lithographic technique |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4772539A (en) |
| EP (1) | EP0291647A3 (en) |
| JP (1) | JPS63244844A (en) |
| CA (1) | CA1326155C (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5139922A (en) * | 1987-04-10 | 1992-08-18 | Matsushita Electronics Corporation | Method of making resist pattern |
| US5186788A (en) * | 1987-07-23 | 1993-02-16 | Matsushita Electric Industrial Co., Ltd. | Fine pattern forming method |
| EP0653679B1 (en) * | 1989-04-28 | 2002-08-21 | Fujitsu Limited | Mask, mask producing method and pattern forming method using mask |
| EP0489542B1 (en) * | 1990-12-05 | 1998-10-21 | AT&T Corp. | Lithographic techniques |
| US5244759A (en) * | 1991-02-27 | 1993-09-14 | At&T Bell Laboratories | Single-alignment-level lithographic technique for achieving self-aligned features |
| US5393634A (en) * | 1993-05-27 | 1995-02-28 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Continuous phase and amplitude holographic elements |
| US6261938B1 (en) | 1997-02-12 | 2001-07-17 | Quantiscript, Inc. | Fabrication of sub-micron etch-resistant metal/semiconductor structures using resistless electron beam lithography |
| CA2197400C (en) * | 1997-02-12 | 2004-08-24 | Universite De Sherbrooke | Fabrication of sub-micron silicide structures on silicon using resistless electron beam lithography |
| US6582861B2 (en) * | 2001-03-16 | 2003-06-24 | Applied Materials, Inc. | Method of reshaping a patterned organic photoresist surface |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3799777A (en) * | 1972-06-20 | 1974-03-26 | Westinghouse Electric Corp | Micro-miniature electronic components by double rejection |
| US3873371A (en) * | 1972-11-07 | 1975-03-25 | Hughes Aircraft Co | Small geometry charge coupled device and process for fabricating same |
| US3920483A (en) * | 1974-11-25 | 1975-11-18 | Ibm | Method of ion implantation through a photoresist mask |
| US4093503A (en) * | 1977-03-07 | 1978-06-06 | International Business Machines Corporation | Method for fabricating ultra-narrow metallic lines |
| DE2927824A1 (en) * | 1978-07-12 | 1980-01-31 | Vlsi Technology Res Ass | SEMICONDUCTOR DEVICES AND THEIR PRODUCTION |
| JPS5596942A (en) * | 1979-01-19 | 1980-07-23 | Matsushita Electric Ind Co Ltd | Method and apparatus for producing minute pattern |
| US4231811A (en) * | 1979-09-13 | 1980-11-04 | Intel Corporation | Variable thickness self-aligned photoresist process |
| EP0037708B1 (en) * | 1980-04-02 | 1986-07-30 | Hitachi, Ltd. | Method of forming patterns |
| FR2486251A1 (en) * | 1980-07-03 | 1982-01-08 | Commissariat Energie Atomique | METHOD FOR PRODUCING AN OPTICAL NETWORK |
| US4451738A (en) * | 1980-07-28 | 1984-05-29 | National Research Development Corporation | Microcircuit fabrication |
| US4438556A (en) * | 1981-01-12 | 1984-03-27 | Tokyo Shibaura Denki Kabushiki Kaisha | Method of forming doped polycrystalline silicon pattern by selective implantation and plasma etching of undoped regions |
| US4377437A (en) * | 1981-05-22 | 1983-03-22 | Bell Telephone Laboratories, Incorporated | Device lithography by selective ion implantation |
| JPS57208142A (en) * | 1981-06-17 | 1982-12-21 | Toshiba Corp | Method for forming fine pattern |
| JPS5892223A (en) * | 1981-11-27 | 1983-06-01 | Matsushita Electronics Corp | Resist pattern formation |
| US4551417A (en) * | 1982-06-08 | 1985-11-05 | Nec Corporation | Method of forming patterns in manufacturing microelectronic devices |
| US4394211A (en) * | 1982-09-08 | 1983-07-19 | Fujitsu Limited | Method of manufacturing a semiconductor device having a layer of polymide resin |
| NL8301262A (en) * | 1983-04-11 | 1984-11-01 | Philips Nv | METHOD FOR MANUFACTURING A SEMICONDUCTOR DEVICE APPLYING PATTERNS IN A LOW SILICON NITRIDE USING AN ION IMPLANTATION |
| JPS59202636A (en) * | 1983-05-04 | 1984-11-16 | Hitachi Ltd | Formation of fine pattern |
| US4569124A (en) * | 1984-05-22 | 1986-02-11 | Hughes Aircraft Company | Method for forming thin conducting lines by ion implantation and preferential etching |
| JPS6343320A (en) * | 1986-08-08 | 1988-02-24 | Matsushita Electric Ind Co Ltd | Manufacture of semiconductor device |
-
1987
- 1987-03-23 US US07/029,110 patent/US4772539A/en not_active Expired - Fee Related
-
1988
- 1988-01-15 CA CA000556672A patent/CA1326155C/en not_active Expired - Fee Related
- 1988-02-17 JP JP63032991A patent/JPS63244844A/en active Pending
- 1988-03-04 EP EP19880103372 patent/EP0291647A3/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0291647A3 (en) | 1991-06-12 |
| EP0291647A2 (en) | 1988-11-23 |
| JPS63244844A (en) | 1988-10-12 |
| US4772539A (en) | 1988-09-20 |
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