Compositions and processes for photolithography

1. A composition suitable for use in forming a topcoat layer over a layer of photoresist, the composition comprising:

a matrix polymer which is aqueous alkali soluble;

a first additive polymer which is aqueous alkali soluble and comprises polymerized units of a monomer of the following general formula (I):

wherein: R 1 is hydrogen or a C1 to C6 alkyl or fluoroalkyl group; R 2 is a C3 to C8 branched alkylene group; and R 3 is a C1 to C4 fluoroalkyl group; and

wherein the first additive polymer is present in the composition in an amount less than the matrix polymer, the first additive polymer has a lower surface energy than a surface energy of the matrix polymer and the first additive polymer is substantially immiscible with the matrix polymer; and

a solvent system comprising a mixture of different solvents to achieve effective phase separation of the first additive polymer from other polymer(s) in the composition;

wherein a layer of the composition in a dried state has a water receding contact angle of from 75 to 85°.

2. The composition of claim 1 , wherein the first additive polymer further comprises polymerized units of a monomer of the following general formula (II) and/or of a monomer of the following general formula (III):

wherein: R 4 and R 9 are independently hydrogen or a C1 to C6 alkyl or fluoroalkyl; R 5 is an optionally substituted C3 to C10 cycloalkyl or C3 to C10 branched alkyl group; R 6 is an optionally substituted C1 to C6 alkylene group; R 7 and R 8 are each independently a to C4 fluoroalkyl group; and R 10 is an acid labile leaving group.

3. The composition of claim 2 , wherein the first additive polymer comprises polymerized units of monomers of the general formulae (II) and (III).

4. The composition of claim 1 , wherein the matrix polymer comprises one or more fluorinated groups.

5. The composition of claim 1 , further comprising a second additive polymer comprising one or more strong acid groups.

6. The composition of claim 1 , wherein the solvent system comprises a mixture of: an alcohol; an alkyl ether and/or an alkane; and a dialkyl glycol mono-alkyl ether.

7. A coated substrate, comprising:

a photoresist layer on a substrate; and

a topcoat layer comprising a composition of claim 1 on the photoresist layer.

8. A method of processing a photoresist composition, comprising:

(a) applying a photoresist composition over a substrate to form a photoresist layer;

(b) applying over the photoresist layer the composition of claim 1 to form a topcoat layer; and

(c) exposing the topcoat layer and the photoresist layer to actinic radiation.

9. The method of claim 8 , wherein the exposure is an immersion exposure and the substrate is a semiconductor wafer.

10. The method of claim 8 , wherein the topcoat layer is self-segregated.

11. The method of claim 8 , wherein the first additive polymer further comprises polymerized units of a monomer of the following general formula (II) and/or of a monomer of the following general formula (III):

wherein: R 4 and R 9 are independently hydrogen or a C1 to C6 alkyl or fluoroalkyl; R 5 is an optionally substituted C3 to C10 cycloalkyl or C3 to C10 branched alkyl group; R 6 is an optionally substituted C1 to C6 alkylene group; R 7 and R 8 are each independently a C1 to C4 fluoroalkyl group; and R 10 is an acid labile leaving group.

12. The method of claim 11 , wherein the first additive polymer comprises polymerized units of monomers of the general formulae (II) and (III).

13. The method of claim 8 , wherein the matrix polymer comprises one or more fluorinated groups.

14. The method of claim 8 , further comprising a second additive polymer comprising one or more strong acid groups.

15. The method of claim 8 , wherein the solvent system comprises a mixture of: an alcohol; an alkyl ether and/or an alkane; and a dialkyl glycol mono-alkyl ether.