Positive resist composition and pattern-forming method using the same

1. A positive resist composition containing:

(A) a resin capable of increasing its solubility in an alkali developer by action of an acid and not containing a silicon atom;

(B) a compound capable of generating an acid upon irradiation with actinic ray or radiation,

(C) from 0.1 to 5 mass % of a total solids content in the composition of a silicon atom-containing resin having at least one group selected from groups (X) to (Z),

(X) an alkali-soluble group,

(Y) a group capable of decomposing by action of an alkali developer to increase the solubility of resin (C) in an alkali developer,

(Z) a group capable of decomposing by action of an acid to increase the solubility of resin (C) in an alkali developer; and

(D) a solvent.

2. The positive resist composition as claimed in claim 1 ,

wherein the resin (A) has a monocyclic or polycyclic alicyclic hydrocarbon structure.

3. The positive resist composition as claimed in claim 1 ,

wherein the silicon atom-containing resin (C) is a silicon atom-containing resin that is alkali-soluble and/or capable of increasing its solubility in an alkali developer by action of an acid.

4. The positive resist composition as claimed in claim 1 ,

wherein the silicon atom-containing resin (C) is a resin that is alkali-soluble and does not increase its solubility in an alkali developer by action of an acid.

5. The positive resist composition as claimed in claim 1 ,

wherein the silicon atom-containing resin (C) has at least one kind of repeating unit having a lactone group.

6. The positive resist composition as claimed in claim 1 ,

wherein the silicon atom-containing resin (C) is a resin that is alkali-insoluble and capable of increasing its solubility in an alkali developer by action of an acid.

7. The positive resist composition as claimed in claim 1 , which is exposed with vacuum ultraviolet rays of wavelengths of 200 nm or less.

8. The positive resist composition as claimed in claim 1 ,

wherein the weight average molecular weight of the silicon atom-containing resin (C) is from 1,000 to 100,000.

9. The positive resist composition as claimed in claim 1 ,

wherein the silicon atom-containing resin (C) further contains a fluorine atom.

10. The positive resist composition as claimed in claim 1 ,

wherein the resin (A) has a repeating unit having an alicyclic hydrocarbon group substituted with a hydroxyl group or a cyano group.

11. A pattern-forming method comprising:

forming a resist film with the resist composition as claimed in claim 1 ;

exposing the resist film; and

developing the exposed resist film.

12. The positive resist composition as claimed in claim 1 , wherein the silicon atom-containing resin (C) has the alkali-soluble group (X), and wherein the alkali-soluble group (X) is a carboxylic acid group, a fluorinated alcohol group or a sulfonylimido group.