US 10,423,068 B2  92  91  Specific examples of the repeating unit having an alkali› soluble group are shown below, but the present invention is  not limited thereto.  (in the formulae, Rx represents H, CH$_{3}$ ,  CF$_{3}$ ,  or CH$_{2}$OH)  OH  OH  OH  j:  OH  Rx  Rx  I  I  --fCH2-Cr- --fCH2-Cr- {=o  Fo  OH  0  ~OOOH  ~  COOR  Rx  I  ~  ---fCH~~~  HN..._J  S- HN,_J  S- Ii  Ii  0  0  Rx  I  ---fCH~~~_’A  HN..._J  S  0  II  0  Rx  I  ---fCH~{--- 0  H  0  N.....__~- 11  0  0  It is preferable that the resin (Ab) has a repeating unit  having an alkali-soluble group. Examples of the alkali› soluble group include a carboxyl group, a sulfonamido  group, a sulfonylimide group, a bisulfonylimide group, and  an aliphatic alcohol with the Va-position being substituted  with an electron-withdrawing group (for example, a hexaflu› oroisopropanol group). The resin (Ab) more preferably has  a repeating unit having a carboxyl group. By virtue of  containing a repeating unit having an alkali-soluble group,  the resolution increases in the usage of forming contact  holes. As the repeating unit having an alkali-soluble group,  all of a repeating unit in which an alkali-soluble group is  directly bonded to the main chain of the resin, such as a  repeating unit with an acrylic acid or a methacrylic acid, a  repeating unit in which an alkali-soluble group is bonded to  the main chain of the resin through a linking group, and a  repeating unit in which an alkali-soluble group is introduced  into the polymer chain terminal by using a polymerization  initiator or a chain transfer agent containing an alkali› soluble group during the polymerization, are preferable. The  linking group may have a cyclic hydrocarbon structure  which is monocyclic or polycyclic. A repeating unit with an  acrylic acid or a methacrylic acid is particularly preferable.  The content of the repeating units having an alkali-soluble  group is preferably 0% to 20% by mole, more preferably 3%  to 15% by mole, and still more preferably 5% to 10% by  mole, with respect to all the repeating units in the resin (Ab). 