Claims
- 1. A novel copolymer comprising:
a repeating unit (B) derived from an unsaturated carboxylic anhydride; a repeating unit (C) represented by Formula (II); and a repeating unit (D) represented by Formula (III): 17wherein R1 is a hydrogen atom or a methyl group; and R2 is an alkyl group having from 1 to 4 carbon atoms.
- 2. A novel copolymer according to claim 1, wherein said repeating unit (B) is a repeating unit (B-1) derived from a unsaturated cyclic carboxylic anhydride.
- 3. A novel copolymer according to claim 2, wherein said repeating unit (B-1) is a unit (B-2) represented by Formula (V):
- 4. A novel copolymer according to claim 2, wherein said repeating unit (B-1) is a unit (B-3) represented by Formula (XVI):
- 5. A novel copolymer according to claim 1, wherein said repeating unit (D) is a unit (D-1) represented by Formula (VI):
- 6. A novel copolymer according to claim 1, wherein the content of repeating unit (B) is equal to or more than 15% and equal to or less than 60% of all repeating units constituting said novel copolymer.
- 7. A novel copolymer according to claim 1, wherein the content of repeating unit (C) is equal to or more than 10% and equal to or less than 40% of all repeating units constituting said novel copolymer.
- 8. A novel copolymer according to claim 1, wherein the content of repeating unit (D) is more than 0% and equal to or less than 40% of all repeating units constituting said novel copolymer.
- 9. A novel copolymer according to any one of claims 1 to 8, wherein said novel copolymer has a weight average molecular weight (Mw) in terms of polystyrene of from 7000 to 30000 and a molecular-weight distribution (Mw/Mn, where Mn is a number average molecular weight) of equal to or less than 3.5.
- 10. A photoresist composition comprising:
a novel copolymer according to claim 1;a photosensitive acid generator; and an organic solvent.
- 11. A photoresist composition according to claim 10, wherein said photosensitive acid generator is a triphenylsulfonium-based onium salt.
- 12. A photoresist composition according to claim 10, wherein said organic solvent is propylene glycol monomethyl ether acetate (PGMEA).
- 13. A process for forming a resist pattern with a high aspect ratio, said process comprising the steps of:
(a) applying a first resist on a substrate and drying the applied first resist to thereby form a first resist layer, applying a photoresist composition of claim 10 onto the first resist layer and drying the applied photoresist composition to thereby form a second resist layer; (b) exposing the second resist layer to imaging radiation, subjecting the exposed second resist layer to a heat treatment, and dissolving and removing exposed portions or unexposed portions of the second resist layer by developing in an alkaline aqueous solution to thereby form a resist pattern; (c) applying a silylation agent onto the formed resist pattern, rinsing the applied resist pattern to thereby enlarge the resist pattern and to form a silylation coating on the % resist pattern, said silylation coating being resistant to corrosion induced by oxygen-containing plasma etching; and (d) etching the first resist layer under the second resist layer with oxygen-containing plasma by using, as a mask, the enlarged resist pattern carrying the silylation coating.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-214451 |
Jul 2000 |
JP |
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of application Ser. No. 09/901,657 filed Jul. 11, 2001, the disclosure of which is incorporated herein by reference.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09901657 |
Jul 2001 |
US |
Child |
10685432 |
Oct 2003 |
US |