US 2020/0050106 Al  Feb. 13, 2020  14  [0199]  The lactone structural moiety may have a substitu› ent (Rb$_{2}$). Preferred examples of the substituent (Rb 2 )  include an alkyl group having 1 to 8 carbon atoms, a  cycloalkyl group having 4 to 7 carbon atoms, an alkoxy  group having 1 to 8 carbon atoms, an alkoxycarbonyl group  having 1 to 8 carbon atoms, a carboxyl group, a halogen  atom, a hydroxyl group, a cyano group, and an acid› decomposable group. n$_{2 }$ represents an integer ofO to 4. In a  case where n$_{2 }$ is 2 or more, the substituents (Rb$_{2}$) which are  present in plural number may be the same as or different  from each other, and the substituents (Rb$_{2}$ )  which are present  in plural number may be bonded to each other to form a ring.  [0200]  Examples of the repeating unit having a group  having a lactone structure represented by any one of General  Formulae (LCl-1) to (LCl-17) include a repeating unit  represented by General Formula (AI).  [0201]  In General Formula (AI), Rb$_{0 }$ represents a hydro› gen atom, a halogen atom, or an alkyl group having 1 to 4  carbon atoms.  [0202]  Preferred examples of the substituent which may  be contained in the alkyl group of Rb$_{0 }$ include a hydroxyl  group and a halogen atom.  [0203]  Examples of the halogen atom of Rb$_{0 }$ include a  fluorine atom, a chlorine atom, a bromine atom, and an  iodine atom. As Rb$_{0}$ ,  a hydrogen atom or a methyl group is  preferable.  -continued  LCl-6  LCl-7  LCl-8  LCl-9  LCl-10  LCl-11  LCl-12  LCl-13  (Al)  ry  COO-Ab-V  LCl-17  LCl-16  LCl-15  -continued  LCl-14  $  0 