Intermediate layer composition for three-layer resist process and pattern formation method using the same

1. An intermediate layer composition for a three-layer resist process comprising (A) an octakis(silsesquioxane) skeleton-containing polymer obtained by hydrosilylation polymerization of a compound represented by the following formula (I) with a compound represented by the following formula (II) in the presence of a platinum-containing catalyst:

wherein R a to R h each independently represent a hydrogen atom, a halogen atom or an alkyl group, and at least two of R a to R h are hydrogen atoms;

R 1 —C≡C—(R 2 ) a —C≡C—R 3   (II)

wherein R 1 and R 3 each independently represent a monovalent organic or organometallic group, R 2 represents a bivalent organic or organometallic group, and a represents 0 or 1.

2. The intermediate layer composition as claimed in claim 1 , wherein the polymer of component (A) is obtained by hydrosilylation polymerization of pentacyclo[9.5.1.1 3,9 .1 5,15 .1 7,13 ] octasiloxane (PCOSI) with the bis (substituted ethynyl) compound represented by formula (II) in a molar ratio of 2:1 to 1:4 in the presence of a platinum-containing catalyst.

3. The intermediate layer composition as claimed in claim 1 , which further comprises (B) a radical initiator.

4. The intermediate layer composition as claimed in claim 1 , which further comprises (C) a crosslinking agent.

5. The intermediate layer composition as claimed in claim 1 , which further comprises (D) a compound generating an acid by heat.

6. The intermediate layer composition as claimed in claim 1 , which further comprises (E) a solvent.

7. The intermediate layer composition as claimed in claim 1 , which further comprises (F) a surfactant.

8. A pattern formation method comprising the steps of:

(a) forming a lower resist layer containing an organic material on a substrate;

(b) applying an intermediate layer on the lower resist layer;

(c) applying an upper resist layer containing an organic material crosslinkable or decomposable by radiation exposure on the intermediate layer;

(d) forming a pattern on the upper resist layer; and

(e) successively etching the intermediate layer, the lower resist layer and the substrate;

wherein the intermediate layer comprises the intermediate layer composition as claimed in claim 1 .

9. The pattern formation method as claimed in claim 8 , which further comprises the step of backing the intermediate layer to insolubilize in an organic solvent.