-continued  38  US 8,906,600 B2  37  (B65)  9  --O-s0  (B66)  9  O-O-s0  (B68)  (  ffis o  3  (B67)  -0  -0  (B69)  In formula (BS-1 ), each R independently represents any of  a hydrogen atom, an alkyl group (linear or branched), a  cycloalkyl group (monocyclic or polycyclic), an aryl group  and an aralkyl group, but it is not allowed that three Rall are  a hydrogen atom.  The carbon number of the alkyl group as R is not particu› larly limited but is usually from 1 to 20, preferably from 1 to  12.  The carbon number of the cycloalkyl group as R is not  particularly limited but is usually from 3 to 20, preferably  from 5 to 15.  The content of the acid generator (B) in the composition is  preferably from 5 to 50 mass  %, more preferably from 8 to 40  mass %, still more preferably from 10 to 40 mass %, based on  the entire solid content of the resist composition.  [3] (C) Basic Compound  The positive resist composition of the present invention  preferably contains a basic compound.  The basic compound is preferably a nitrogen-containing  organic basic compound.  The usable compound is not particularly limited, but, for  example, compounds classified into the following (1) to (4)  are preferably used.  (1) Compound Represented by the Following Formula (BS- 1 ):  The carbon number of the ary 1 group as R is not particularly  limited but is usually from 6 to 20, preferably from 6 to 10.  Specific examples of the aryl group include a phenyl group  and a naphthyl group.  The carbon number of the aralkyl group as R is not par› ticularly limited but is usually from 7 to 20, preferably from 7  to 11. Specific examples of the aralkyl group include a benzyl  group.  In the alkyl group, cycloalkyl group, aryl group and aralkyl  group as R, a hydrogen atom may be replaced by a substitu› ent. Examples of the substituent include an alkyl group, a  cycloalkyl group, an aryl group, an aralkyl group, a hydroxyl  group, a carboxyl group, an alkoxy group, an aryloxy group,  an alkylcarbonyloxy group and an alkyloxycarbonyl group.  In the compound represented by formula (BS-1 ), it is pre› ferred that only one of three Risa hydrogen atom or all Rare  not a hydrogen atom.  (BS-1)  R  I  R-N-R 