US 2019/0243238 Al  19  Aug. 8, 2019  and the like using azobisisobutyronitrile (AIBN) as the  radical initiator, thereby obtaining polymer A-2 shown  below (weight average molecular weight: approximately  10000). In the following formula, relations of a=0.4, b=0.4,  and c=0.2 are satisfied, however, the monomer ratio of the  unit in the polymer of some embodiments of the present  invention is not limited to the followings.  (A-2)  [0189]  Monomers which constitute each of the constitut› ing unit are polymerized by known radical polymerization  and the like using azobisisobutyronitrile (AIBN) as the  radical initiator, thereby obtaining polymer A-3 shown  below (weight average molecular weight: approximately  10000). In the following formula, relations of a=0.4, b=0.4,  and c=0.2 are satisfied, however, the monomer ratio of the  unit in the polymer of some embodiments of the present  invention is not limited to the followings.  (A-3)  <Preparation of Resist Composition>  [0190]  Either one of polymer (A-1), polymer (A-2), and  polymer (A-3) as the base polymer (100 parts by mass),  tellurium containing sulfonium salt 1 as the photoacid  generator (8 parts by mass), and propylene glycol monom› ethyl ether acetate as the solvent (1800 parts by mass) are  mixed, followed by filtration using a PTFE filter, thereby  preparing a resist composition (H-1). Details of the resist  composition are shown in Table 1.  [0191]  Either one of the tellurium containing sulfonium  salts 2 to 4 synthesized as above are used by the formulation  amount shown in Table 1 in place of the tellurium containing  sulfonium salt 1 as the photoacid generator, and the rest of  the conditions are carried out in a similar manner as  Example 1 to obtain the resist compositions (H-2) to (H-12).  [0192]  Either one of the photoacid generators (B-1) to  (B-4) are used by the formulation amount shown in Table 1  in place of the tellurium containing sulfonium salt 1 as the  photoacid generator, and the rest of the conditions are  carried out in a similar manner as Example 1 to obtain the  resist compositions (H-13) to (H-24).  [0193]  Here, the photoacid generators (B-1) to (B-4) are  shown below.  Synthesis Example 10  Synthesis of Polymer (A-3)  <Synthesis of Polymer (A-3)>  Example 1  Examples 2 to 12  Comparative Examples 1 to 12  [Chemical Formula 23]  [Chemical Formula 24] 