Jul. 30, 2020  92  US 2020/0241414 Al  a hydroxyl, cyano, carbonyl, ether bond, ester bond, sulfonic  acid ester bond, carbonate, lactone ring, sultone ring, car› boxylic anhydride or haloalkyl moiety. Of the heteroatoms,  oxygen is preferred.  [0136]  Of the PAGs having formula (2), those having  formula (2’) are preferred.  [0137]  In formula (2’), LA is as defined above.  RHF  is  hydrogen or trifluoromethyl, preferably trifluoromethyl.  R 301 ,  R $^{302 }$and  R $^{303 }$are each independently hydrogen or a  C$_{1 }$-C$_{20 }$ monovalent hydrocarbon group which may contain a  heteroatom. The monovalent hydrocarbon groups may be  straight, branched or cyclic, and examples thereof are as  exemplified above for  R  107 . The subscripts x and y are each  independently an integer of O to 5, and z is an integer of 0  to 4.  [0138]  Examples of the PAG having formula (2) are  shown below, but not limited thereto. Notably,  RHF  is as  defined above.  (2’)  -continued 