CA1250177A - Process for preparing negative relief images - Google Patents
Process for preparing negative relief imagesInfo
- Publication number
- CA1250177A CA1250177A CA000496973A CA496973A CA1250177A CA 1250177 A CA1250177 A CA 1250177A CA 000496973 A CA000496973 A CA 000496973A CA 496973 A CA496973 A CA 496973A CA 1250177 A CA1250177 A CA 1250177A
- Authority
- CA
- Canada
- Prior art keywords
- film
- monomer
- cationic
- cationic photoinitiator
- substrate
- 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
Links
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
- G03F7/26—Processing photosensitive materials; Apparatus therefor
- G03F7/265—Selective reaction with inorganic or organometallic reagents after image-wise exposure, e.g. silylation
Abstract
PROCESS FOR PREPARING NEGATIVE RELIEF IMAGES
Abstract of the Disclosure Negative relief images are generated by a process comprising the use of cationic polymerization and plasma etching.
Abstract of the Disclosure Negative relief images are generated by a process comprising the use of cationic polymerization and plasma etching.
Description
~2Sq~7 PROCESS FOR PREPARING NEGATIVE RELIEF IMAGES
DESCRIPTION
Technical Field The present invention is concerned with a process for generating a negative relief image. The process allows convenient generation of high resolution, high aspect ratio relief structures useful in semiconductor manufacturing.
Background Art U.S. patent 4,426,247 shows a multi-step process for obtaining micropatterns. The process of that patent involves radical addition graft polymerization, and involves steps different from tilose of the present invention.
lS U.S. patent 4,175,963 shows a process involving cationic polymerization, but the patent is entirely silent on the preparation of relief images.
Disclosure of the Invention According to the present invention, a negative tone relief image is generated by carrying out the following steps:
1. A substrate is coated with a film of cationic photoinitiator;
DESCRIPTION
Technical Field The present invention is concerned with a process for generating a negative relief image. The process allows convenient generation of high resolution, high aspect ratio relief structures useful in semiconductor manufacturing.
Background Art U.S. patent 4,426,247 shows a multi-step process for obtaining micropatterns. The process of that patent involves radical addition graft polymerization, and involves steps different from tilose of the present invention.
lS U.S. patent 4,175,963 shows a process involving cationic polymerization, but the patent is entirely silent on the preparation of relief images.
Disclosure of the Invention According to the present invention, a negative tone relief image is generated by carrying out the following steps:
1. A substrate is coated with a film of cationic photoinitiator;
2. The initiator film is imagewise exposed to produce cationic ini;tiator species;
3. The film is then contacted with a monomer that is susceptible to cationic polymerization, and fo~ms a polymer resistant to plasma etching;
4. The film is then placed into a plasma environment. The unexposed areas of the film are etched by plasma treatment, but the exposed areas are not etched. This results in a high resolution negative tone relief image.
The substrate may be inorganic or organic in nature. The process can, for example be carried out directly on semiconductor substrates or semiconductor substrates that have been coated with an etchable substrate such as an organic polymer planarizing layer.
Description of the Drawings .
lS An understanding of the process may be obtained by an inspection of the single drawing appended hereto.
The drawing (not to scale) is a diagrammatic representation of an embodiment of the steps of the process.
A substrate (such as silicon) is coated with an etchable substrate such as a polymeric layer containing (at least on its surface) a cationic photoinitiator. The photoinitiator is next imagewise exposed to radiation, and then contacted with a monomer which polymerizes. The film is then plasma etched to form a negative tone relief ~5 image.
The process used in the present invention can take several forms. The coating process step can be carried out in several ways: a) the pure initiator can be applied directly to the substrate by spin coating, spraying or roller coating from solution; b) certain ~5~
initiators can be applied by direct evaporation or sputtering in vacuo; or c) the initiator can be applied in a carrier (host) polymer by the usual coating techni~ues.
A preferred material for the substrate is silicon.
Also useful are the oxides and nitrides of silicon.
The exposure can be carried out over a wide range of the electromagnetic spectrum from x-radiation to visible light or by electron beams, depending upon the structure of the initiator and the use of dye sensitizers well known in the art.
The exposure can be carried out under ambient conditions and the exposed substrates/films can be transported and stored under normal atmospheric conditions prior to contacting ~ith the polymerizable monomer. The process need not be carried out in vacuo.
'rhe monomer must be susceptible to cationic polymerization. The contact process, during which polymer is grown on the surface of the exposed regions, can be carried out either in the vapor phase or in solution. Film ranging from a few angstroms to several microns in thickness can be grown by this process.
Organometallic monomers are particularly useful and form polymers which are particularly resistant to plasma etching.
The dry etching step is used to etch the areas of the substrate or planarizing polymer film where the polymer has not grown. A common method of dry etching employs plasma such as oxyyen or halocarbon plasma, or reactive ion etching (RIE).
~5~7 The process employed in the presenk invention has several distinct advantages over the prior art.
Radiation grafting via radical processes has been employed in this regard. This process is sensitive to oxygen and must, therefore, be carried out in vacuo or under inert atmosphere to preserve the reactive radical species. The cationic initiator species of the present invention are not oxygen sensitive; hence, the process can be carried out in a normal ambient. The radical grafting process demands the use of a radiation sensitive polymer and in this process, the grafted polymer is covalently attached to the radiation sensitive polymer.'In the present invention, no host polymer is required, and if one is used, it can be chosen for optimal coating, planarizing and adhesion characteristics rather than radiation sensitivity.
The composition of the present invention can also take many forms. The cationic photoinitiator can be any of several known in the art. These include, but are not ~0 restricted to, triarylsulfonium salts, with or without dye sensitizers, diaryliodonium salts with or without dye sensitizers, aryl diazonium salts, trihalomethyltriazenes and others. Host polymers useful in this invention are many. Examples include polystyrene, poly(p-methoxystyrene), polycarbonates, butvar and others. The polymerizable monomers include, but are not restricted to, compounds from the following classes: a) epoxides, vinyl ethers, substituted styrenes and a-methylstyrenes and cyclosiloxanes. The organometallic element useful in this invention include but are not restricted to silicon, germanium and tin.
A Preferred Embodiment A 4~ thick film of photoresist was spin coated onto a silicon substrate and baked at 200C for two hours.
This organic substrate was spin coated with a 0.2~ film of poly(p-methoxystyrene) containing triphenyl sulfonium hexafluoro arsenate (1% to 25% by weight). The film was exposed through a mask to 254 nm radiation (dose: 4mJ/cm ) under typical laboratory atmospheric conditions. The exposed film was transferred to a closed reaction vessel which was evacuated, then filled with vapors of ~~glycidoxypropyltrimethoxysilane and allowed to stand for lO minutes. The vessel was then evacuated, refilled with N2 and the film was removed and transferred into a Tegal parallel plate etch tool. The relief image was fully developed after two hours at 100 watts R.f., at 50 m Torr at 20 SCCM of oxygen. High quality images were obtained without loss of thickness in the exposed areas.
In a second preferred embodiment, a 4-micron thick film of hardened photoresist on a silicon wafer was coated with a 0.5~ film of poly(p-methoxystyrene) containing 20 weight % of di-(p-t-butyl phenyl) phenylsulfonium hexafluoro arsenate. The resulting structure was imagewise exposed to 14mJ/cm2 of deep UV
light. It was then immersed in a 5% solution of 4-vinylphenyl t-butyldimethylsilyl ether in petroleum ether for one minute. It was removed, blown dry and then baked for 5 minutes at 100. The oxygen plasma development was accomplished as before (80 minutes) to give a high resolution, high aspect ratio image of the mask without thickness loss in the exposed areas.
Only preferred embodiments of the invention have been described above, and one skilled in the art will recognize that numerous substitutions, modifications and alterations are permissible without departing from the spirit and scope of the invention, as demonstrated in the following claims.
i
The substrate may be inorganic or organic in nature. The process can, for example be carried out directly on semiconductor substrates or semiconductor substrates that have been coated with an etchable substrate such as an organic polymer planarizing layer.
Description of the Drawings .
lS An understanding of the process may be obtained by an inspection of the single drawing appended hereto.
The drawing (not to scale) is a diagrammatic representation of an embodiment of the steps of the process.
A substrate (such as silicon) is coated with an etchable substrate such as a polymeric layer containing (at least on its surface) a cationic photoinitiator. The photoinitiator is next imagewise exposed to radiation, and then contacted with a monomer which polymerizes. The film is then plasma etched to form a negative tone relief ~5 image.
The process used in the present invention can take several forms. The coating process step can be carried out in several ways: a) the pure initiator can be applied directly to the substrate by spin coating, spraying or roller coating from solution; b) certain ~5~
initiators can be applied by direct evaporation or sputtering in vacuo; or c) the initiator can be applied in a carrier (host) polymer by the usual coating techni~ues.
A preferred material for the substrate is silicon.
Also useful are the oxides and nitrides of silicon.
The exposure can be carried out over a wide range of the electromagnetic spectrum from x-radiation to visible light or by electron beams, depending upon the structure of the initiator and the use of dye sensitizers well known in the art.
The exposure can be carried out under ambient conditions and the exposed substrates/films can be transported and stored under normal atmospheric conditions prior to contacting ~ith the polymerizable monomer. The process need not be carried out in vacuo.
'rhe monomer must be susceptible to cationic polymerization. The contact process, during which polymer is grown on the surface of the exposed regions, can be carried out either in the vapor phase or in solution. Film ranging from a few angstroms to several microns in thickness can be grown by this process.
Organometallic monomers are particularly useful and form polymers which are particularly resistant to plasma etching.
The dry etching step is used to etch the areas of the substrate or planarizing polymer film where the polymer has not grown. A common method of dry etching employs plasma such as oxyyen or halocarbon plasma, or reactive ion etching (RIE).
~5~7 The process employed in the presenk invention has several distinct advantages over the prior art.
Radiation grafting via radical processes has been employed in this regard. This process is sensitive to oxygen and must, therefore, be carried out in vacuo or under inert atmosphere to preserve the reactive radical species. The cationic initiator species of the present invention are not oxygen sensitive; hence, the process can be carried out in a normal ambient. The radical grafting process demands the use of a radiation sensitive polymer and in this process, the grafted polymer is covalently attached to the radiation sensitive polymer.'In the present invention, no host polymer is required, and if one is used, it can be chosen for optimal coating, planarizing and adhesion characteristics rather than radiation sensitivity.
The composition of the present invention can also take many forms. The cationic photoinitiator can be any of several known in the art. These include, but are not ~0 restricted to, triarylsulfonium salts, with or without dye sensitizers, diaryliodonium salts with or without dye sensitizers, aryl diazonium salts, trihalomethyltriazenes and others. Host polymers useful in this invention are many. Examples include polystyrene, poly(p-methoxystyrene), polycarbonates, butvar and others. The polymerizable monomers include, but are not restricted to, compounds from the following classes: a) epoxides, vinyl ethers, substituted styrenes and a-methylstyrenes and cyclosiloxanes. The organometallic element useful in this invention include but are not restricted to silicon, germanium and tin.
A Preferred Embodiment A 4~ thick film of photoresist was spin coated onto a silicon substrate and baked at 200C for two hours.
This organic substrate was spin coated with a 0.2~ film of poly(p-methoxystyrene) containing triphenyl sulfonium hexafluoro arsenate (1% to 25% by weight). The film was exposed through a mask to 254 nm radiation (dose: 4mJ/cm ) under typical laboratory atmospheric conditions. The exposed film was transferred to a closed reaction vessel which was evacuated, then filled with vapors of ~~glycidoxypropyltrimethoxysilane and allowed to stand for lO minutes. The vessel was then evacuated, refilled with N2 and the film was removed and transferred into a Tegal parallel plate etch tool. The relief image was fully developed after two hours at 100 watts R.f., at 50 m Torr at 20 SCCM of oxygen. High quality images were obtained without loss of thickness in the exposed areas.
In a second preferred embodiment, a 4-micron thick film of hardened photoresist on a silicon wafer was coated with a 0.5~ film of poly(p-methoxystyrene) containing 20 weight % of di-(p-t-butyl phenyl) phenylsulfonium hexafluoro arsenate. The resulting structure was imagewise exposed to 14mJ/cm2 of deep UV
light. It was then immersed in a 5% solution of 4-vinylphenyl t-butyldimethylsilyl ether in petroleum ether for one minute. It was removed, blown dry and then baked for 5 minutes at 100. The oxygen plasma development was accomplished as before (80 minutes) to give a high resolution, high aspect ratio image of the mask without thickness loss in the exposed areas.
Only preferred embodiments of the invention have been described above, and one skilled in the art will recognize that numerous substitutions, modifications and alterations are permissible without departing from the spirit and scope of the invention, as demonstrated in the following claims.
i
Claims (14)
1. A process for generating a negative tone resist image comprising the steps of:
(1) coating a substrate with a film that contains a cationic photoinitiator;
(2) exposing the film in an imagewise fashion to radiation and thereby generating cationic initiator in the exposed regions of the film;
(3) treating the exposed film with a cationic-sensitive monomer to form a film of polymer resistant to plasma etching; and (4) developing the resist image by etching with a plasma.
(1) coating a substrate with a film that contains a cationic photoinitiator;
(2) exposing the film in an imagewise fashion to radiation and thereby generating cationic initiator in the exposed regions of the film;
(3) treating the exposed film with a cationic-sensitive monomer to form a film of polymer resistant to plasma etching; and (4) developing the resist image by etching with a plasma.
2. A process as claimed in claim 1 wherein the cationic photoinitiator is applied from solution.
3. A process as claimed in claim 1 wherein the cationic photoinitiator is applied by an evaporative technique.
4. A process as claimed in claim 1 wherein the cationic photoinitiator is dispersed within a carrier polymer.
5. A process as claimed in claim 4 where the carrier polymer is poly(p-methoxystyrene).
6. A process as claimed in claim 1 where the cationic photoinitiator is a triarylsulfonium salt.
7. A process as claimed in claim 1 where the cationic photoinitiator is a trihalomethyltriazine.
8. A process as claimed in claim 1 wherein the monomer is an epoxy substituted siloxane or silane.
9. A process as claimed in claim 1 wherein the monomer is a styrene silyl ether.
10. A process as claimed in claim 1 wherein the monomer is a silyl substituted vinyl ether.
11. A process as claimed in claim 1 where the monomer is dissolved in a solvent.
12. A process as claimed in claim 1 wherein the monomer is in the vapor state.
13. A process as claimed in claim 1 where the substrate is silicon.
14. A process as claimed in claim 1 wherein the substrate is a planarizing polymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/702,514 | 1985-02-19 | ||
| US06/702,514 US4551418A (en) | 1985-02-19 | 1985-02-19 | Process for preparing negative relief images with cationic photopolymerization |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1250177A true CA1250177A (en) | 1989-02-21 |
Family
ID=24821515
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000496973A Expired CA1250177A (en) | 1985-02-19 | 1985-12-05 | Process for preparing negative relief images |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4551418A (en) |
| EP (1) | EP0192078B1 (en) |
| JP (1) | JPS61189639A (en) |
| CA (1) | CA1250177A (en) |
| DE (1) | DE3667553D1 (en) |
Families Citing this family (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4981909A (en) * | 1985-03-19 | 1991-01-01 | International Business Machines Corporation | Plasma-resistant polymeric material, preparation thereof, and use thereof |
| US4782008A (en) * | 1985-03-19 | 1988-11-01 | International Business Machines Corporation | Plasma-resistant polymeric material, preparation thereof, and use thereof |
| US4751170A (en) * | 1985-07-26 | 1988-06-14 | Nippon Telegraph And Telephone Corporation | Silylation method onto surface of polymer membrane and pattern formation process by the utilization of silylation method |
| US4702792A (en) * | 1985-10-28 | 1987-10-27 | International Business Machines Corporation | Method of forming fine conductive lines, patterns and connectors |
| DE3541327A1 (en) * | 1985-11-22 | 1987-05-27 | Schwerionenforsch Gmbh | SPREADING PLATE FOR COLLECTING A REAL IMAGE IN OPTICAL SYSTEMS |
| EP0233747B1 (en) * | 1986-02-10 | 1992-12-02 | LOCTITE (IRELAND) Ltd. | Vapor deposited photoresists of anionically polymerizable monomers |
| US4737425A (en) * | 1986-06-10 | 1988-04-12 | International Business Machines Corporation | Patterned resist and process |
| EP0258719A3 (en) * | 1986-08-30 | 1989-07-05 | Ciba-Geigy Ag | Two-layer system |
| NL8700421A (en) * | 1987-02-20 | 1988-09-16 | Philips Nv | METHOD FOR MANUFACTURING A SEMICONDUCTOR DEVICE |
| US4768291A (en) * | 1987-03-12 | 1988-09-06 | Monarch Technologies Corporation | Apparatus for dry processing a semiconductor wafer |
| US4764247A (en) * | 1987-03-18 | 1988-08-16 | Syn Labs, Inc. | Silicon containing resists |
| US4968582A (en) * | 1988-06-28 | 1990-11-06 | Mcnc And University Of Nc At Charlotte | Photoresists resistant to oxygen plasmas |
| US5114827A (en) * | 1988-06-28 | 1992-05-19 | Microelectronics Center Of N.C. | Photoresists resistant to oxygen plasmas |
| US5041362A (en) * | 1989-07-06 | 1991-08-20 | Texas Instruments Incorporated | Dry developable resist etch chemistry |
| CA2019669A1 (en) * | 1989-11-21 | 1991-05-21 | John Woods | Anionically polymerizable monomers, polymers thereof, and use of such polymers in photoresists |
| US4988741A (en) * | 1989-11-27 | 1991-01-29 | General Electric Company | Controlled release compositions and use |
| US5464538A (en) * | 1989-12-29 | 1995-11-07 | The Dow Chemical Company | Reverse osmosis membrane |
| US5238747A (en) * | 1989-12-29 | 1993-08-24 | The Dow Chemical Company | Photocurable compositions |
| US5310581A (en) * | 1989-12-29 | 1994-05-10 | The Dow Chemical Company | Photocurable compositions |
| DE59010396D1 (en) * | 1990-04-27 | 1996-08-01 | Siemens Ag | Process for producing a resist structure |
| ES2090218T3 (en) * | 1990-12-20 | 1996-10-16 | Siemens Ag | PHOTOLITHOGRAPHIC STRUCTURAL GENERATION. |
| US5550007A (en) * | 1993-05-28 | 1996-08-27 | Lucent Technologies Inc. | Surface-imaging technique for lithographic processes for device fabrication |
| US5733706A (en) * | 1994-05-25 | 1998-03-31 | Siemens Aktiengesellschaft | Dry-developable positive resist |
| US5707783A (en) * | 1995-12-04 | 1998-01-13 | Complex Fluid Systems, Inc. | Mixtures of mono- and DI- or polyfunctional silanes as silylating agents for top surface imaging |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4175963A (en) * | 1974-05-02 | 1979-11-27 | General Electric Company | Method of exposing and curing an epoxy composition containing an aromatic onium salt |
| US3924520A (en) * | 1974-06-27 | 1975-12-09 | Hercules Inc | Preparing lithographic plates utilizing vinyl monomers containing hydrolyzable silane groups |
| US4307177A (en) * | 1975-12-09 | 1981-12-22 | General Electric Company | Method of using polymerizable compositions containing onium salts |
| US4081276A (en) * | 1976-10-18 | 1978-03-28 | General Electric Company | Photographic method |
| FR2389922B1 (en) * | 1977-05-03 | 1981-08-28 | Thomson Csf | |
| JPS5886726A (en) * | 1981-11-19 | 1983-05-24 | Nippon Telegr & Teleph Corp <Ntt> | Forming method for pattern |
| US4426247A (en) * | 1982-04-12 | 1984-01-17 | Nippon Telegraph & Telephone Public Corporation | Method for forming micropattern |
| JPS5961928A (en) * | 1982-10-01 | 1984-04-09 | Hitachi Ltd | Pattern formation |
| US4460436A (en) * | 1983-09-06 | 1984-07-17 | International Business Machines Corporation | Deposition of polymer films by means of ion beams |
| JPS60501777A (en) * | 1983-11-02 | 1985-10-17 | ヒユ−ズ・エアクラフト・カンパニ− | Silicon dioxide based graft polymerization lithography mask |
| US4552833A (en) * | 1984-05-14 | 1985-11-12 | International Business Machines Corporation | Radiation sensitive and oxygen plasma developable resist |
-
1985
- 1985-02-19 US US06/702,514 patent/US4551418A/en not_active Expired - Lifetime
- 1985-12-05 CA CA000496973A patent/CA1250177A/en not_active Expired
- 1985-12-27 JP JP60293415A patent/JPS61189639A/en active Granted
-
1986
- 1986-01-24 EP EP86100926A patent/EP0192078B1/en not_active Expired
- 1986-01-24 DE DE8686100926T patent/DE3667553D1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE3667553D1 (en) | 1990-01-18 |
| EP0192078B1 (en) | 1989-12-13 |
| US4551418A (en) | 1985-11-05 |
| EP0192078A3 (en) | 1988-07-13 |
| JPH0523430B2 (en) | 1993-04-02 |
| EP0192078A2 (en) | 1986-08-27 |
| JPS61189639A (en) | 1986-08-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |