33  US 9,958,775 B2  34  the polymer compound preferably includes at least one kind  of repeating unit having a phenolic hydroxyl group. The  repeating unit having a phenolic hydroxyl group is not  particularly limited, however, a repeating unit represented  by the following general formula (1) is preferable.  [Chem. 22]  In the general formula (1 ),  Ru represents a hydrogen atom, a methyl group which  may have a substituent, or a halogen atom;  B$_{1 }$ represents a single bond or a divalent linking group;  Ar represents an aromatic ring; and  ml represents an integer of 1 or more.  As a methyl group which may have a substituent in Ru,  a trifluoromethyl group, a hydroxymethyl group, and the like  are included.  Ru is preferably a hydrogen atom or a methyl group and  a hydrogen atom is preferable for the reason of develop› ability.  As the divalent linking group of Bi, a carbonyl group, an  alkylene group (preferably 1 to 10 carbon atoms and more  preferably 1 to 5), a sulfonyl group (-S(=O)$_{2}$ -),  ---0-,  -NH- or a divalent linking group in combination thereof  is preferable.  B$_{1 }$ preferably represents a single bond, a carbonyloxy  group (-C(=O)---0-), or----C(=O)-NH-, more pref› erably represents a single bond, a carbonyloxy group (----C  (=0)-0-), and is particularly preferably a single bond  from the viewpint of the improvement of dry etching resis› tance.  An aromatic ring of Ar is monocyclic or polycyclic  aromatic ring, and includes an aromatic hydrocarbon ring  having 6 to 18 carbon atoms such as a benzene ring, a  naphthalene ring, an anthracene ring, a fluorene ring or a  phenanthrene ring, which may have a substituent or, for  example, an aromatic ring heterocycle having a heterocycle  such as a thiophene ring, a furan ring, a pyrrole ring, a  benzothiophene ring, a benzofuran ring, a benzopyrrole ring,  a triazine ring, a imidazole ring, a benzoimidazole ring, a  triazole ring, a thiadiazole ring or a thiazole ring. Among  these, a benzene ring and a naphthalene ring are preferable  from the viewpoint of resolution and a benzene ring is most  preferable from the viewpoint of sensitivity.  ml is preferably an integer of 1 to 5, and most preferably  1. When ml is 1 and Ar is a benzene ring, the position of  substitution of -OH may be the para-position, the meta› position, or the ortho-position with respect to the bonding  position of a benzene ring to B $_{1 }$ (  a polymer main chain when 60  B$_{1 }$ is a single bond), however from the viewpoint of cross› linking reactivity, the para-position and the meta-position  are preferred, and the para-position is more preferred.  The aromatic ring of Ar may also have a substituent other  than a group represented by -OH described above, and 65  examples of the substituent include an alkyl group, a  cycloalkyl group, a halogen atom, a hydroxyl group, an  alkoxy group, a carboxyl group, an alkoxycarbonyl group,  an alkylcarbonyl group, an alkylcarbonyloxy group, an  alkylsulfonyloxy group, and an arylcarbonyl group.  The repeating unit having a phenolic hydroxyl group is  more preferably a repeating unit represented by the follow› ing general formula (2) for the reasons of cross-linking  reactivity, developability and  dry  etching resistance.  In the general formula (2),  R$_{12 }$ represents a hydrogen atom or a methyl group;  Ar represents an aromatic ring; and  R$_{12 }$ represents a hydrogen atom or a methyl group and is  preferably a hydrogen atom for the reason of develop› ability.  Ar in the general formula (2) is the same as Ar in the  general formula (1) and the same as the preferred range. The  repeating unit represented by the general formula (2) is  preferably a repeating unit which is induced from hydrox› ystyrene (that is, in the general formula (2), a repeating unit  wherein R$_{12 }$ is a hydrogen atom and Ar is a benzene ring)  from the viewpoint of sensitivity.  The compound (Bl) as a polymer compound may be  configured from only a repeating unit having a phenolic  hydroxyl group as described above. The compound (Bl) as  a polymer compound may have a repeating unit as described  later other than a repeating unit having a phenolic hydroxyl  group as described above. In this case, the content of the  repeating unit having a phenolic hydroxyl group is prefer› ably from 10 to 98% by mo!, more preferably from 30 to  97% by mo!, and even more preferably from 40 to 95% by  mass, with respect to the total repeating units of the com› pound (B 1) as a polymer compound. Thereby, particularly in  a case where the resist film is a thin film (for example, in a  case where the thickness of the resist film is from 10 to 150  nm), the dissolution rate of the exposed portion in the resist  film of the present invention formed by using the compound  (B 1) with respect to an alkali developer can be more reliably  decreased (that is the dissolution rate of the resist film using  the compound (Bl) can be more reliably controlled to be  optimal). As a result, sensitivity can be more reliably  increased.  Hereinafter, examples of the repeating unit having a  phenolic hydroxyl group will be described, but the present  invention is not limited thereto.  [Chem. 24]  OH  OH  R12  ~ $_{Ar }$ I  OH  R11  ~ $_{B1 }$ I  Ar  I  (OH)m1  (2)  (l) 10 [Chem. 23] 