PHOTORESIST TOPCOAT COMPOSITIONS AND PATTERN FORMATION METHODS

1 . A photoresist topcoat composition, comprising:

a first polymer that is fluorinated, comprising:

first polymerized units formed from a monomer of formula (1):

wherein: R 1 represents a hydrogen atom, a fluorine atom, a C1-C4 alkyl group, or a C1-C4 fluoroalkyl group; R 2 and R 3 independently represent a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group; R 4 represents a substituted or unsubstituted C1-C4 alkylene group; and X represents a carbon atom, wherein:

(i) at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 cycloalkyl group; or

(ii) at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 alkyl group that comprises a branched structure when taken with X; or

(iii) R 2 and R 3 together form a ring; and

second polymerized units formed from a monomer of formula (2):

wherein: R 5 represents a hydrogen atom, a fluorine atom, a C1-C4 alkyl group, or a C1-C4 fluoroalkyl group; R 6 represents a substituted or unsubstituted C1-C4 alkylene group; and Rf 1 independently represents a C1-C4 fluoroalkyl group;

wherein: the total content of polymerized units of formula (1) in the first polymer is from 1 to 80 wt% based on total polymerized units of the first polymer; and wherein the first polymer is present in the composition in an amount of from 1 to 20 wt% based on total solids of the composition;

a second polymer; and

an organic-based solvent system comprising an ester solvent and one or more additional organic solvents;

wherein the composition is substantially free of photoacid generator compounds.

2 . The photoresist topcoat composition of claim 1 , wherein the one or more additional organic solvents comprise an alcohol solvent.

3 . The photoresist topcoat composition of claim 2 , wherein the ester solvent is isobutyl isobutyrate or isoamyl acetate and the alcohol solvent is methyl isobutyl carbinol.

4 . The photoresist topcoat composition of claim 1 , wherein the photoresist topcoat composition further comprises a third polymer that is fluorinated that is different from the first and second polymers.

5 . The photoresist topcoat composition of claim 4 , further comprising a fourth polymer that is different from the first, second and third polymers.

6 . The photoresist topcoat composition of claim 1 , wherein at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 cycloalkyl group.

7 . The photoresist topcoat composition of claim 1 , wherein at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 alkyl group that comprises a branched structure when taken with X.

8 . The photoresist topcoat composition of claim 1 , wherein each Rf 1 is a trifluoromethyl group.

9 . A pattern formation method, comprising:

(a) forming a photoresist layer on a substrate;

(b) forming a photoresist topcoat layer on the photoresist layer;

(c) exposing the photoresist topcoat layer and the photoresist layer to activating radiation; and

(d) contacting the exposed topcoat layer and photoresist layer with a developer to form a resist pattern;

wherein the photoresist topcoat layer is formed from a photoresist topcoat composition comprising:

a first polymer that is fluorinated, comprising:

first polymerized units formed from a monomer of formula (1):

wherein: R 1 represents a hydrogen atom, a fluorine atom, a C1-C4 alkyl group, or a C1-C4 fluoroalkyl group; R 2 and R 3 independently represent a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group; R 4 represents a substituted or unsubstituted C1-C4 alkylene group; and X represents a carbon atom, wherein:

(i) at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 cycloalkyl group; or

(ii) at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 alkyl group that comprises a branched structure when taken with X; or

(iii) R 2 and R 3 together form a ring; and

second polymerized units formed from a monomer of formula (2):

wherein: R 5 represents a hydrogen atom, a fluorine atom, a C1-C4 alkyl group, or a C1-C4 fluoroalkyl group; R 6 represents a substituted or unsubstituted C1-C4 alkylene group; and Rf 1 independently represents a C1-C4 fluoroalkyl group;

wherein: the total content of polymerized units of formula (1) in the first polymer is from 1 to 80 wt% based on total polymerized units of the first polymer; and wherein the first polymer is present in the composition in an amount of from 1 to 20 wt% based on total solids of the composition;

a second polymer; and

an organic-based solvent system comprising an ester solvent and one or more additional organic solvents;

wherein the composition is substantially free of photoacid generator compounds.

10 . The method of claim 9 , wherein the topcoat layer is formed by spin-coating, and the first polymer migrates to an upper surface of the topcoat layer during the spin-coating, wherein an upper surface of the topcoat layer consists essentially of the first polymer.

11 . The method of claim 9 , wherein the one or more additional organic solvents comprise an alcohol solvent.

12 . The method of claim 11 , wherein the ester solvent is isobutyl isobutyrate or isoamyl acetate and the alcohol solvent is methyl isobutyl carbinol.

13 . The method of claim 9 , wherein the photoresist topcoat composition further comprises a third polymer that is fluorinated that is different from the first and second polymers.

14 . The method of claim 13 , further comprising a fourth polymer that is different from the first, second and third polymers.

15 . The method of claim 9 , wherein at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 cycloalkyl group.

16 . The method of claim 9 , wherein at least one of R 2 and R 3 represents a substituted or unsubstituted C3-C8 alkyl group that comprises a branched structure when taken with X.

17 . The method of any of claim 9 , wherein each Rf 1 is a trifluoromethyl group.