Positive resist composition

1. A positive resist composition comprising (A) polysiloxane or polysilsesquioxane that has a property of increasing solubility in an alkali developing solution by the action of an acid and contains a group capable of being decomposed with an acid, (B) a compound that generates a sulfonic acid upon irradiation of an actinic ray or radiation, (C) an organic basic compound, and (D) a compound that generates a carboxylic acid upon irradiation of an actinic ray or radiation, wherein an amount of the compound that generates a sultonic acid upon irradiation of an actinic ray or radiation is from 6 to 20% by weight based on the total solid content of the positive resist composition, and the polysiloxane or polysilsesquioxane (A) has a structure represented by formula (1) shown below in the side chain thereof:

-( J 1) k -( J 2) l -( J 3) m -( J 4) n -( J 5) p   (1)

wherein, J1 represents an alkylene group; J2 represents an arylene group or a cycloalkylene group; J3 represents a group selected from —O—, —N(R 1 )—, —COO—, —OC(═O)—, —O(C═O)—, —CON(R 1 )—, —N(R 1 )CO— and —NH—CO—NH—, in which R 1 represents a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms; J4 represents a divalent, trivalent or tetravalent connecting group; J5 represents a group capable of being decomposed by the action of an acid; m represents 1; k, l and n each independently represent 0 or 1; and p represents an integer of from 1 to 3.

2. The positive resist composition as claimed in claim 1 , wherein an amount of the organic basic compound (C) is from 0.05 to 1.0% by weight based on the total solid content of the positive resist composition.

3. The positive resist composition as claimed in claim 1 , wherein a light source for exposure is any one of an electron beam, an X ray and an EUV beam.

4. The positive resist composition as claimed in claim 1 , which further comprises a fluorine-based and/or silicon-based surfactant.

5. The positive resist composition as claimed in claim 1 , wherein the compound that generates a carboxylic acid upon irradiation of an actinic ray or radiation has a structure represented by the following formula (D):

wherein R 10 to R 12 each independently represents an alkyl group, an alkenyl group or an aryl group; R 13 represents a hydrogen atom, an alkyl group, an alkenyl group or an aryl group; and Z represents a sulfur atom or an iodine atom, provided that in the case where Z represents a sulfur atom, p is 1; and in the case where Z represents an iodine atom, p is 0.

6. The positive resist composition as claimed in claim 1 , wherein the ratio of the compound of Component (B)/the compound of Component (D) is 99.9/0.1 to 50/50 by weight.

7. The positive resist composition as claimed in claim 1 , wherein the ratio of the compound of Component (B)/the compound of Component (D) is 99/1 to 60/40 by weight.

8. The positive resist composition as claimed in claim 1 , wherein the ratio of the compound of Component (B)/the compound of Component (D) is 98/2 to 70/30 by weight.