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Among these acid generators, preferred are the compounds represented by formulae (PAGl), (PAG2) and (PAG4), and more preferred are the compounds represented by formulae (PAGl) and (PAG2). 

The acid generator is preferably a compound of generating an organic sulfonic acid upon irradiation with actinic rays or radiation [hereinafter, this compound is sometimes referred to as a "component (B 1 )"]. Examples of the component (B 1) include those where the counter anion z- or x- in formulae (PAGl), (PAG2) and (PAG6) is a sulfonate anion. 

In addition to the compound (B 1 ), a compound of gener› ating a carboxylic acid upon irradiation with actinic rays or radiation [hereinafter, this compound is sometimes referred to as a "component (B2)"] is preferably further contained as the component (B). By using the components (Bl) and (B2) in combination, various performances such as sensitivity and resolution can be enhanced. Examples of the component (B2) include those where the counter anion z- or x- in formulae (PAGl), (PAG2) and (PAG6) is a carboxylate anion. 

The mass ratio of component (Bl )/component (B2) is usu› ally from 1/1 to 100/1, preferably from 1/1 to 10/1. 

One of the compounds for the component (Bl) or (B2) may be used alone or two or more thereof may be used in combi› nation. 

The amount added of the compound of decomposing upon irradiation with actinic rays or radiation to generate an acid is, as a total amount, usually from 0.001 to 40 mass %, prefer› ably from 0.01 to 20 mass%, more preferably from 0.1 to 10 mass %, based on the solid content in the composition. The amount added of the compound of decomposing upon irra› diation with actinic rays or radiation to generate an acid is preferably 0.001 mass % or more in view of sensitivity and preferably 40 mass% or less in view of film shape and profile. 

[3] Organic Basic Compound (C) 

The organic basic compound contained in the resist com› position of the present invention is preferably a compound having a basicity stronger than phenol. The molecular weight of the organic basic compound is usually from 100 to 900, preferably from 150 to 800, more preferably from 200 to 700. In particular, a nitrogen-containing basic compound is pre› ferred. 

As for the preferred chemical environment of the nitrogen› containing basic compound, a compound having a structure represented by any one of the following formulae (A) to (E) is preferred. The structures of formulae (B) to (E) each may form a part of a ring structure. 

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In these formulae, R 250 , R $^{251 }$and R252 , which may be the same or different, each represents a hydrogen atom, an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 1 to 20 carbon atoms or a substituted or unsub- stituted aryl group having from 6 to 20 carbon atoms, and R$^{251 }$and R$^{252 }$may combine with each other to form a ring. 

The alkyl group may or may not have a substituent. The alkyl group having a substituent is preferably an aminoalkyl group having from 1 to 6 carbon atoms or a hydroxyalkyl group having from 1 to 6 carbon atoms. 253 254 255 256 

R , R , R and R , which may be the same or different, each represents an alkyl group having from 1 to 6 carbon atoms. 

The compound is more preferably a nitrogen-containing basic compound having two or more nitrogen atoms differing in the chemical environment within one molecule, still more preferably a compound containing both a substituted or unsubstituted amino group and a ring structure containing a nitrogen atom, or a compound containing an alkylamino group. 

Specific preferred examples thereof include guanidine, aminopyridine, aminoalkylpyridine, aminopyrrolidine, inda› zole, imidazole, pyrazole, pyrazine, pyrimidine, purine, imi› dazoline, pyrazoline, piperazine, aminomorpholine and ami- noalkylmorpholine. These compounds each may have a substituent and preferred examples of the substituent include an amino group, an aminoalkyl group, an alkylamino group, an aminoaryl group, an arylamino group, an alkyl group, an alkoxy group, an acyl group, an acyloxy group, an aryl group, an aryloxy group, a nitro group, a hydroxyl group and a cyano group. 

Particularly preferred examples of the compound include, but are not limited to, guanidine, 1, 1-dimethylguanidine, 1, 1, 3,3-tetramethylguanidine, imidazole, 2-methylimidazole, 4-methylimidazole, N-methylimidazole, 2-phenylimidazole, 4,5-diphenylimidazole, 2,4,5-triphenylimidazole, 2-ami› nopyridine, 3-aminopyridine, 4-aminopyridine, 2-dimethy› laminopyridine, 4-dimethylaminopyridine, 2-diethylami› nopyridine, 2-(aminomethyl)pyridine, 2-amino-3- methylpyridine, 2-amino-4-methylpyridine, 2-amino-5- methylpyridine, 2-amino-6-methylpyridine, 3-aminoethyl› pyridine, 4-aminoethylpyridine, 3-aminopyrrolidine, piperazine, N-(2-aminoethyl)piperazine, N-(2-aminoethyl) piperidine, 4-amino-2,2,6,6-tetramethylpiperidine, 4-piperi- dinopiperidine, 2-iminopiperidine, 1-(2-aminoethyl)pyrroli› dine, pyrazole, 3-amino-5-methylpyrazole, 5-amino-3- methyl-1-p-tolylpyrazole, pyrazine, 2-(aminomethyl)-5- methylpyrazine, pyrimidine, 2,4-diaminopyrimidine, 4,6- dihydroxypyrimidine, 2-pyrazoline, 3-pyrazoline, N-aminomorpholine and N-(2-aminoethyl)morpholine. 

(A) 

A tetraalkylammonium salt-type nitrogen-containing basic compound can also be used. In particular, a tetraalky› lammonium hydroxide having from 1 to 8 carbon atoms, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-(n-butyl)animoniumhydroxide, is preferred. These nitrogen-containing basic compounds are used indi› vidually or in combination of two or more thereof 

(B) 

(C) 

The ratio of the acid generator and the organic basic com› pound used in the composition is preferably acid generator/ organic basic compound (by mol)=2.5 to 300. That is, the molar ratio is preferably 2.5 or more in view of sensitivity and resolution and preferably 300 or less from the standpoint of preventing the resolution from decreasing due to thickening of the resist pattern in aging after exposure until heat treat› ment. The ratio ofacid generator/ organic basic compound (by mo!) is more preferably from 5.0 to 200, still more preferably from 7.0 to 150. 

(D) 

(E) 

