PATTERN FORMATION METHODS

1 . A pattern formation method, comprising:

(a) providing a semiconductor substrate comprising one or more layers to be patterned;

(b) forming a photoresist layer over the one or more layers to be patterned, wherein the photoresist layer is formed from a composition that comprises: a matrix polymer comprising a unit having an acid labile group; a photoacid generator; and an organic solvent;

(c) coating a photoresist overcoat composition over the photoresist layer, wherein the overcoat composition comprises: a matrix polymer; an additive polymer; a basic quencher; and an organic solvent; wherein the additive polymer has a lower surface energy than a surface energy of the matrix polymer, and wherein the additive polymer is present in the overcoat composition in an amount of from 1 to 20 wt % based on total solids of the overcoat composition;

(d) exposing the photoresist layer to activating radiation;

(e) heating the substrate in a post-exposure bake process; and

(f) developing the exposed film with an organic solvent developer.

2 . The method of claim 1 , wherein the additive polymer comprises a unit containing a silicon atom.

3 . The method of claim 1 , wherein the additive polymer comprises a unit containing a fluorine atom.

4 . The method of claim 3 , wherein the additive polymer comprises a unit containing a fluoroalcohol.

5 . The method of claim 1 , wherein the matrix polymer comprises a unit formed from a monomer of the following general formula (I):

wherein: R 1 is chosen from hydrogen and optionally substituted C1 to C3 alkyl; R 2 is chosen from optionally substituted C1 to C15 alkyl; X 1 is oxygen, sulfur or is represented by the formula NR 3 , wherein R 3 is chosen from hydrogen and optionally substituted C1 to C10 alkyl; and Z 1 is a single bond or a spacer unit chosen from optionally substituted aliphatic and aromatic hydrocarbons, and combinations thereof, optionally with one or more linking moiety chosen from —O—, —S—, —COO— and —CONR 4 — wherein R 4 is chosen from hydrogen and optionally substituted C1 to C10 alkyl.

6 . The method of claim 1 , wherein the additive polymer is formed from a monomer having the following general formula (II) or (III):

wherein: R 10 is chosen from hydrogen and optionally substituted C1 to C3 alkyl; R 11 is chosen from optionally substituted C1 to C15 alkyl; X 2 is oxygen, sulfur or is represented by the formula NR 12 , wherein R 12 is chosen from hydrogen and optionally substituted C1 to C10 alkyl; and Z 3 is a single bond or a spacer unit chosen from optionally substituted aliphatic and aromatic hydrocarbons, and combinations thereof, optionally with one or more linking moiety chosen from —O—, —S—, —NHSO 2 —, —COO— and —CONR 13 — wherein R 13 is chosen from hydrogen and optionally substituted C1 to C10 alkyl;

wherein: R 14 is chosen from hydrogen and optionally substituted C1 to C3 alkyl; R 15 is independently chosen from optionally substituted C1 to C15 alkyl; X 3 is oxygen, sulfur or is represented by the formula NR 16 , wherein R 16 is chosen from hydrogen and optionally substituted C1 to C10 alkyl; Z 4 is a single bond or a spacer unit chosen from optionally substituted aliphatic and aromatic hydrocarbons, and combinations thereof, optionally with one or more linking moiety chosen from —O—, —S—, —COO— and —CONR 17 —, wherein R 17 is chosen from hydrogen and optionally substituted C1 to C10 alkyl; and n is an integer from 0 to 2.

7 . The method of claim 1 , wherein the basic quencher comprises a basic moiety on the matrix polymer.

8 . The method of claim 1 , wherein the basic quencher comprises an additive separate from the matrix polymer.

9 . The method of claim 1 , wherein the additive polymer is present in the overcoat composition in an amount of from 3 to 15 wt % based on total solids of the overcoat composition.

10 . The method of claim 1 , wherein the photoresist layer is exposed to the activating radiation in an immersion lithography process.