Monomer, polymer, positive resist composition and patterning process

A polymer consisting of recurring units (a) of acid labile group-substituted hydroxystyrene having the general formula (2):

• wherein
• is selected from the group consisting of the following groups:
• recurring units selected from sulfonium salt units (b1) to (b3) represented by the general formula (3):
• wherein R30, R34, and R38 each are hydrogen or methyl, R31 is a single bond, phenylene, —O—R42—, or —C(═O)—Y11—R42—, Y11 is oxygen or NH, R42 is a straight, branched or cyclic C1-C6 alkylene group, alkenylene or phenylene group, which may contain a carbonyl, ester, ether or hydroxyl radical, R32, R33, R35, R36, R37, R39, R40, and R41 are each independently a straight, branched or cyclic C1-C12 alkyl group which may contain a carbonyl, ester or ether radical, or a C6-C12 aryl, C7-C20 aralkyl, or thiophenyl group, Z11 is a single bond, methylene, ethylene, phenylene, fluorophenylene, —O—R43—, or —C(═O)—Z12—R43—, Z12 is oxygen or NH, R43 is a straight, branched or cyclic C1-C6 alkylene group, alkenylene or phenylene group, which may contain a carbonyl, ester, ether or hydroxyl radical, M− is a non-nucleophilic counter ion, b1, b2 and b3 are in the range of 0≦b1≦0.3, 0≦b2≦0.3, 0≦b3≦0.3, and 0<b1+b2+b3≦0.3;
• recurring units (c) selected from (meth)acrylic acid and derivatives thereof, styrenecarboxylic acid, and vinylnaphthalenecarboxylic acid, each having an acid labile group substituted thereon, represented by the general formula (4):
• wherein R50 is hydrogen or methyl, R51 is an acid labile group selected from the group consisting of those of the following formulae:
• wherein RL43 is a straight, branched or cyclic C1-C8 alkyl group or C6-C20 aryl group, RL44 and RL46 each are hydrogen or a straight, branched or cyclic C1-C20 alkyl group, X1 is a single bond, —C(═O)—O—R52—, phenylene or naphthylene group, and R52 is a straight, branched or cyclic C1-C10 alkylene group which may have an ester radical, ether radical or lactone ring;
• recurring units having a phenolic hydroxyl group, selected from recurring units (d1) to (d9) represented by the general formula (5):
• wherein R20 is each independently hydrogen or methyl, Y1, Y2 and Y5 each are a single bond or —C(═O)—O—R21—, Y3 and Y4 each are —C(═O)—O—R22—, R21 and R22 each are a single bond or a straight, branched or cyclic C1-C10 alkylene group which may contain an ether or ester radical, Z1 and Z2 each are methylene or ethylene, Z3 is methylene, oxygen or sulfur, Z4 and Z5 each are CH or nitrogen, and p is 1 or 2;
• and
• recurring units (e) having an adhesive group selected from the class consisting of hydroxyl (exclusive of phenolic hydroxyl), lactone ring, ether, ester, carbonyl, cyano, sulfonic acid ester, sulfonamide, cyclic —O—C(═O)—S— and —O—C(═O)—NH—;
• said polymer having a weight average molecular weight of 1,000 to 500,000.