55  US 9,323,153 B2  56  The number of carbon atoms of each of the organic groups  as R$_{20}$ i, R $_{202 }$and R$_{203 }$ is generally in the range of 1 to 30,  preferably 1 to 20. Two members of R$_{201 }$ to R$_{203 }$ may be  bonded to each other to form a ring structure, and the ring  within the same may contain an oxygen atom, a sulfur atom,  an ester bond, an amide bond, or a carbonyl group. Examples  of the group formed by bonding of two members out ofR$_{201 }$ to R$_{203 }$ include an alkylene group such as a butylene group  and a pentylene group.  z- represents the acid anion generated by decomposition  by irradiation with actinic rays or radiation. z- is preferably a  normucleophilic anion. Examples of the normucleophilic  anion include a sulfonate anion, a carboxylate anion, a sulfa- nylimido anion, a bis(alkylsulfonyl)imido anion, and a tris  (alkylsulfonyl)methyl anion.  Furthermore, the normucleophilic anion means an anion  whose capability of inducing a nucleophilic reaction is  extremely low. By using the nucleophilic anion, time course  decomposition by intramolecular nucleophilic reaction can  be inhibited. This would realize an enhancement of the time  course stability of the resin and the composition.  Moreover, examples of the structural portion capable of  generating an acid by irradiation with actinic rays or radiation  include the structural moiety destined for a sulfonic acid  precursor that is introduced in each of the following photo› acid generators. Examples of the photo-acid generators  include the following compounds (1) to (3).  (1) Compounds photolyzed to generate a sulfonic acid  whose representative is an iminosulfonate or the like, as  described in M. Tunooka et al., Polymer Preprints Japan,  35(8); G. Bemer et al., J. Rad. Curing, 13( 4);  W.  J. Mijs et al.,  Coating Technol., 55(697), 45 (1983); H. Adachi et al., Poly› mer Preprints Japan, 37(3); EP0199,672B, EP84515B,  EP199,672B, EP044,115B, and EP0101,122B; U.S. Pat. No.  618,564B, U.S. Pat. No. 4,371,605B and U.S. Pat. No. 4,431,  774B; JP1989-18143A (JP-S64-18143A), JP1990-245756A  (JP-H02-245756A),  and  JP1992-365048A  (JP-H04- 365048A); etc.  (2) Disulfone compounds as  described in JP1986- 166544A (JP-S61-166544A), etc.  (3) Compounds capable of generating an acid by light, as  described in  V.  N. R. Pillai, Synthesis, (1 ), 1 (1980); A. Abad  et al., Tetrahedron Lett., (47) 4555 (1971); D. H. R. Barton et  al., J. Chem. Soc., (C), 329 (1970); U.S. Pat. No. 3,779,778B,  EP126,712B; etc.  Specific examples of the repeating units (B) are shown  below, but the scope of the present invention is not limited  thereto.  [Chem. 28-1]  ---fCH2¢CH;- \  (YJ~  I  ~  ~  SO3  0  -continued 