67  US 9,989,847 B2  68  -continued  -continued  Herein R $^{1}$a, R100 , R 200 , and R $^{300 }$as defined above. L’ is a  C$_{2}$-C$_{5 }$ alkylene group.  RY  is a straight C$_{1 }$-C$_{20 }$or branched or  cyclic C$_{3}$-C$_{20 }$monovalent hydrocarbon group which may be  substituted with or separated by a heteroatom. A is hydrogen  or trifluoromethyl. L" is a single bond or a straight C$_{1 }$-C$_{20 }$ or branched or cyclic C$_{3}$ -C$_{20 }$ divalent hydrocarbon group  which may be substituted with or separated by a heteroatom,  mis O or 1, n is O or 1, with the proviso that n is O when L"  is a single bond.  In formulae (dl) and (d2), R 1$_{a }$ is as defined and exem› plified above. L’ is a C$_{2}$-C$_{5 }$ alkylene group, preferably  ethylene, propylene or butylene. A is hydrogen or trifluo› romethyl, preferably trifluoromethyl.  RY  is a straight C$_{1 }$-C$_{20 }$ or branched or cyclic C$_{3 }$-C$_{20 }$ monovalent hydrocarbon  group, examples of which are as described above for R $^{1 }$to  R$^{5 }$in formula (1 ). L" is a single bond or a straight C$_{1 }$-C$_{20 }$or  branched or cyclic C$_{3}$-C$_{20 }$ divalent hydrocarbon group,  examples of which are as described above for L in formula  (1). R 100 , R $^{200 }$and R$^{300 }$are as described above.  Illustrative structures of the anion moiety in formula (dl)  include those described in JP-A 2010-113209 and JP-A  2007-145797. Illustrative structures of the anion moiety in  formula ( d2) wherein A is hydrogen include those described  in JP-A 2010-1160. Illustrative structures of the anion moi› ety in formula (d2) wherein A is trifluoromethyl include  those described in JP-A 2010-077404.  While the polymer is characterized by comprising recur- ring units having formulae (2) and (3), and optionally  recurring units having formula (dl) or (d2), other recurring  units, typically recurring units of the structure having a  hydroxyl group protected with an acid labile group may be  further copolymerized. The recurring units of the structure  having a hydroxyl group protected with an acid labile group  are not particularly limited as long as the unit has one or  more structures each having protected hydroxyl wherein the  protective group is decomposed under the action of acid to  generate a hydroxyl group. Of these, recurring units of the  structure having the general formula ( e 1) are preferred.  Where the recurring units of formula (3) are incorporated,  units having lactone ring as the polar group are most  preferably used.  While the polymer is characterized by comprising recur› ring units having formulae (2) and (3), optionally recurring  units having the general formula (dl) or (d2) may also be  incorporated.  H  _)::o  $^{0 }$\ $_{L’ }$ -...;,-m  0  ¢_  0-s+-Q  (~  H  ~’j==o- o  ~n  L’  o===<  A~so,  F  RIOO  I  s+-R3oo  I  R200  c+-?-J  ✓  ro  0  ~(  0~  ~OH  c+-?-J  ✓  ro  0  ~ $_{0 }$ 0  c+-?-J  ✓  ro  0  ~ $_{0 }$ 0  OH  OH  (d2)  (el)  (dl) 50 