# US 8,568,960 B2 · Multiple exposure photolithography methods

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- Number: US 8,568,960 B2
- Document ID: US8568960B2
- Status: Granted
- Kind: B2
- Application number: 13/418,421
- Filed: 2012-03-13
- Published: 2012-07-12
- Granted: 2013-10-29
- Earliest claimed: 2008-01-08
- Assignees: International Business Machines Corporation
- Applicants: Kuang-Jung Chen; Wu-Song Huang; Ranee Wai-Ling Kwong; Sen Liu; Pushkara R. Varanasi
- Inventors: Kuang-Jung Chen; Wu-Song Huang; Ranee Wai-Ling Kwong; Sen Liu; Pushkara R. Varanasi
- Web page: https://patentgrep.com/patent/US8568960B2

## CPC

- G03F 7/038: Macromolecular compounds which are rendered insoluble or differentially wettable (G03F7/075 takes precedence; macromolecular azides G03F7/012; macromolecular diazonium compounds G03F7/021)
- G03F 7/0045: {with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors}
- G03F 7/0382: {the macromolecular compound being present in a chemically amplified negative photoresist composition}
- G03F 7/0392: {the macromolecular compound being present in a chemically amplified positive photoresist composition}
- G03F 7/095: having more than one photosensitive layer (G03F7/075 takes precedence)
- G03F 7/20: Exposure; Apparatus therefor (photographic printing apparatus for making copies G03B27/00)
- G03F 7/2022: {Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure}
- G03F 7/30: Imagewise removal using liquid means
- G03F 7/38: Treatment before imagewise removal, e.g. prebaking {(G03F7/265 takes precedence)}
- G03F 7/70466: {Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature (stitching G03F7/70475)}
- Y10S 430/12: Nitrogen compound containing
- 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; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A method that forms a film of photoresist composition on a substrate and exposes a first and second region of the film to radiation through a first and second mask having a first and second image pattern, respectively. The photoresist composition includes a polymer including labile group(s), base soluble group(s), a photosensitive acid generator, and a photosensitive base generator. The photosensitive acid generator generates first and second amounts of acid upon exposure to first and second doses of radiation, respectively. The second amount of acid exceeds the first amount of acid. The second dose of radiation exceeds the first dose of radiation. The photosensitive base generator generates a first and second amount of base upon exposure to the first and second dose of radiation, respectively. The first amount of base exceeds the first amount of acid. The second amount of acid exceeds the second amount of base.

## Claims

### Claim 1

A method comprising:
forming a film of a photoresist composition on a substrate, said photoresist composition comprising a polymer having a structure comprising at least one acid labile group or at least one base soluble group, a photosensitive acid generator, and a photosensitive base generator, said photosensitive acid generator capable of generating a first amount of acid upon exposure to a first dose of radiation, said photosensitive acid generator capable of generating a second amount of acid upon exposure to a second dose of radiation, said second amount of acid greater than said first amount of acid, said second dose of radiation greater than said first dose of radiation, said photosensitive base generator capable of generating a first amount of base upon exposure to said first dose of radiation, said photosensitive base generator capable of generating a second amount of base upon exposure to said second dose of radiation, said first amount of base greater than said first amount of acid, said second amount of base less than said second amount of acid;
exposing a first region of said film to radiation through a first mask having a first image pattern; and
exposing a second region of said film to radiation through a second mask having a second image pattern;
wherein said photoresist composition further comprises a base proliferator, said base proliferator comprising a compound capable of generating a second base through catalytic reaction with a first base;
wherein said base proliferator is selected from the group consisting of:
wherein R4 is hydrogen or alkyl;
wherein either:
(i) each R1, R2, or R3 further comprises at least one element selected from the group consisting of oxygen, sulfur, and nitrogen; or
(ii) each R1 or R2 is independently selected from the group consisting of a fluorinated linear alkyl, a fluorinated branched alkyl, a fluorinated cycloalkyl, an aryl, a fluorinated aryl, and combinations thereof, wherein R3 is selected from the group consisting of a fluorinated linear alkyl, a fluorinated branched alkyl, a fluorinated cycloalkyl, an aryl, a fluorinated aryl, and combinations thereof.

### Claim 2 (depends on 1)

The method of claim 1, wherein each R1, R2, or R3 further comprises at least one element selected from the group consisting of oxygen, sulfur, and nitrogen.

### Claim 3 (depends on 1)

The method of claim 1, wherein each R1 or R2 is independently selected from the group consisting of a fluorinated linear alkyl, a fluorinated branched alkyl, a fluorinated cycloalkyl, an aryl, a fluorinated aryl, and combinations thereof, wherein R3 is selected from the group consisting of a fluorinated linear alkyl, a fluorinated branched alkyl, a fluorinated cycloalkyl, an aryl, a fluorinated aryl, and combinations thereof.

### Claim 4 (depends on 1)

The method of claim 1, said method further comprising
after said exposing said second region, baking said film at a temperature between about 80° C. and about 150° C.; and
after said exposing said first region and before said exposing said second region, baking said film at a temperature between about 80° C. and about 150° C.

### Claim 5 (depends on 1)

The method of claim 1, wherein said first image pattern is different from said second image pattern.

### Claim 6 (depends on 1)

The method of claim 1, said method further comprising:
after said exposing said second region, removing soluble portions of said film to leave a patterned layer remaining, said patterned layer having a photoresist pattern; and
after said removing said soluble portions of said film, transferring said photoresist pattern from said patterned layer to said substrate, said transferring comprising a method selected from the group consisting of depositing, implanting, electroplating, etching and combinations thereof.

### Claim 7 (depends on 1)

The method of claim 1, wherein said photoresist composition comprises a higher concentration of said photosensitive acid generator than said photosensitive base generator.

### Claim 8 (depends on 1)

The method of claim 1, wherein said photosensitive acid generator is selected from the group consisting of (trifluoro-methylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide (MDT), N-hydroxy-naphthalimide dodecane sulfonate (DDSN), onium salts, aromatic diazonium salts, sulfonium salts, diaryliodonium salts, sulfonic acid esters of N-hydroxyamides, imides, and combinations thereof.

### Claim 9 (depends on 1)

The method of claim 1, wherein said photosensitive base generator is selected from the group consisting of carbamates, benzyl carbamates, benzoin carbamates, O-carbamoylhydroxylamines, O-carbamoyloximes, aromatic sulfonamides, α-lactones, N-(2-Arylethenyl)amides, azides, amides, oximines, quaternary ammonium salts, and amineimides.

### Claim 10 (depends on 1)

The method of claim 1, wherein said photosensitive base generator is a carbamate selected from the group consisting of:

### Claim 11

A method comprising:
forming a film of a photoresist composition on a substrate, said photoresist composition comprising a polymer having a structure comprising at least one acid labile group or at least one base soluble group, a photosensitive acid generator, and a photosensitive base generator, said photosensitive acid generator capable of generating a first amount of acid upon exposure to a first dose of radiation, said photosensitive acid generator capable of generating a second amount of acid upon exposure to a second dose of radiation, said second amount of acid greater than said first amount of acid, said second dose of radiation greater than said first dose of radiation, said photosensitive base generator capable of generating a first amount of base upon exposure to said first dose of radiation, said photosensitive base generator capable of generating a second amount of base upon exposure to said second dose of radiation, said first amount of base greater than said first amount of acid, said second amount of base less than said second amount of acid;
exposing a first region of said film to radiation through a first mask having a first image pattern; and
exposing a second region of said film to radiation through a second mask having a second image pattern,
wherein said photosensitive base generator is a carbamate consisting of:

### Claim 12 (depends on 11)

The method of claim 11, said method further comprising
after said exposing said second region, baking said film at a temperature between about 80° C. and about 150° C.; and
after said exposing said first region and before said exposing said second region, baking said film at a temperature between about 80° C. and about 150° C.

### Claim 13 (depends on 11)

The method of claim 11, said method further comprising:
after said exposing said second region, removing soluble portions of said film to leave a patterned layer remaining, said patterned layer having a photoresist pattern; and
after said removing said soluble portions of said film, transferring said photoresist pattern from said patterned layer to said substrate, said transferring comprising a method selected from the group consisting of depositing, implanting, electroplating, etching and combinations thereof.

### Claim 14 (depends on 11)

The method of claim 11, wherein said photoresist composition comprises a higher concentration of said photosensitive acid generator than said photosensitive base generator.

### Claim 15 (depends on 11)

The method of claim 11, said photoresist composition further comprising a base proliferator, said base proliferator comprising a compound capable of generating a second base through catalytic reaction with a first base.

### Claim 16 (depends on 15)

The method of claim 15, wherein said base proliferator is selected from the group consisting of fluorenylmethyl carbamates, phenylsulfonylethyl carbamates, and 3-nitropentane-2-yl carbamates.

### Claim 17

A method comprising:
forming a film of a photoresist composition on a substrate, said photoresist composition comprising a polymer having a structure comprising at least one acid labile group or at least one base soluble group, a photosensitive acid generator, and a photosensitive base generator, said photosensitive acid generator capable of generating a first amount of acid upon exposure to a first dose of radiation, said photosensitive acid generator capable of generating a second amount of acid upon exposure to a second dose of radiation, said second amount of acid greater than said first amount of acid, said second dose of radiation greater than said first dose of radiation, said photosensitive base generator capable of generating a first amount of base upon exposure to said first dose of radiation, said photosensitive base generator capable of generating a second amount of base upon exposure to said second dose of radiation, said first amount of base greater than said first amount of acid, said second amount of base less than said second amount of acid;
exposing a first region of said film to radiation through a first mask having a first image pattern; and
exposing a second region of said film to radiation through a second mask having a second image pattern,
said photoresist composition further comprising a base proliferator, said base proliferator comprising a compound capable of generating a second base through catalytic reaction with a first base, wherein said base proliferator is selected from the group consisting of 3-nitropentane-2-yl carbamates.

### Claim 18 (depends on 17)

The method of claim 17, wherein said photosensitive acid generator is selected from the group consisting of (trifluoro-methylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide (MDT), N-hydroxy-naphthalimide dodecane sulfonate (DDSN), onium salts, aromatic diazonium salts, sulfonium salts, diaryliodonium salts, sulfonic acid esters of N-hydroxyamides, imides, and combinations thereof.

### Claim 19 (depends on 17)

The method of claim 17, wherein said photosensitive base generator is selected from the group consisting of carbamates, benzyl carbamates, benzoin carbamates, O-carbamoylhydroxylamines, O-carbamoyloximes, aromatic sulfonamides, α-lactones, N-(2-Arylethenyl)amides, azides, amides, oximines, quaternary ammonium salts, and amineimides.

### Claim 20 (depends on 17)

The method of claim 17, wherein said photosensitive base generator is a carbamate selected from the group consisting of: