30  US 7,504,193 B2  29  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.  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.  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.  R 253 , R 254 , R 255  and R 256 , 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  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  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.  [3] Organic Basic Compound (C)  R2s1  I  R2so_ N-R2s2  I  I  -N-C=N- I  I  =C-N=C- I  I  =C-N- r54  1  r55  R253_C-N-C-R2s6  I  I  (A) (B)  (C)  (D)  (E) 