Pattern trimming methods

1. A method of trimming a photoresist pattern, comprising:

(a) providing a semiconductor substrate;

(b) forming a photoresist pattern over the semiconductor substrate, wherein the photoresist pattern is formed from a photoresist composition comprising: a first polymer comprising acid labile groups; and a photoacid generator;

(c) coating a pattern trimming composition over the photoresist pattern, wherein the pattern trimming composition comprises a second polymer and a solvent system, wherein the solvent system comprises one or more monoether solvents in a combined amount of 50 wt % or more based on the solvent system, and one or more alcohol and/or ester solvents in a combined amount of from 2 to 50 wt % based on the solvent system;

(d) heating the coated semiconductor substrate, thereby causing a change in solubility of a surface region of the photoresist pattern in a rinsing agent to be applied; and

(e) contacting the photoresist pattern with a rinsing agent to remove the surface region of the photoresist pattern, thereby forming a trimmed photoresist pattern.

2. The method of claim 1 , wherein the first polymer comprises a repeat unit of the following formula (III):

wherein: R 2 is hydrogen or methyl; R 3 is one or more groups chosen from hydroxyl, C1-C8 alkoxy, C5-C12 aryloxy, C2-C10 alkoxycarbonyloxy, C1-C4 alkyl, C5-C15 aryl and C6-C20 aralkyl, wherein one or more carbon hydrogens are optionally substituted with a halogen atom; b is an integer of from 1 to 5; wherein at least one R 3 is independently chosen from hydroxyl, C1-C8 alkoxy, C5-C12 aryloxy and C2-C10 alkoxycarbonyloxy.

3. The method of claim 1 , wherein forming the photoresist pattern comprises exposing a layer formed from the photoresist composition to EUV radiation.

4. The method of claim 1 , wherein forming the photoresist pattern comprises exposing a layer formed from the photoresist composition to radiation having a wavelength of 248 nm.

5. The method of claim 1 , wherein the solvent system comprises a C4-C8 monohydric alcohol and/or an alkyl ester having a total carbon number of from 4 to 10.

6. The method of claim 1 , wherein the one or more monoether solvents comprise an alkyl monoether and/or an aromatic monoether having a total carbon number of from 6 to 16.

7. The method of claim 1 , wherein the solvent system comprises: diisoamyl ether or anisole; and 4-methyl-2-pentanol.

8. The method of claim 1 , wherein the second polymer is soluble in the rinsing agent.

9. The method of claim 1 , wherein the second polymer comprises a repeat unit comprising a —C(CF3) 2 OH group and/or a repeat unit formed from a (meth)acrylic acid monomer.

10. The method of claim 1 , wherein the pattern trimming composition further comprises a non-polymeric acid or an acid generator.

11. The method of claim 1 , wherein the pattern trimming composition is free of non-polymeric acids and acid generators.

12. The method of claim 1 , wherein the rinsing agent is an aqueous tetramethylammonium hydroxide solution.