Patterning process

A pattern forming process comprising the steps of applying a resist composition onto a substrate, post-applied baking the composition to form a resist film, exposing the resist film to high-energy radiation, post-exposure baking the resist film, and developing the exposed resist film in an organic solvent-based developer to selectively dissolve the unexposed region of the resist film to form a negative pattern,

• the resist composition comprising a base resin, an acid generator, and an organic solvent, the base resin being a hydrogenated product of a ring-opening metathesis polymerization polymer comprising recurring units (A) including a partial structure having a carboxyl group protected with an acid labile group, represented by the general formula (1), and recurring units (B) having a lactone structure, represented by the general formula (3) or (4), the recurring units (A) and (B) each being of at least one type,
• wherein at least one of R1 to R4 is a functional group having the general formula (2):
• wherein the broken line denotes a valence bond, R5 is hydrogen, C1-C10 straight, branched or cyclic alkyl, C2-C10 straight, branched or cyclic alkoxyalkyl, or C1-C10 straight, branched or cyclic acyl, R6 is an acid labile group, W1 is a single bond or a (k+2)-valent C1-C10 hydrocarbon group, and k is 0 or 1, the remains of R1 to R4 are each independently hydrogen, C1-C20 straight, branched or cyclic alkyl, halogen, C1-C20 straight, branched or cyclic haloalkyl, C1-C20 straight, branched or cyclic alkoxy, C2-C20 straight, branched or cyclic alkoxyalkyl, or C2-C20 straight, branched or cyclic alkylcarbonyloxy, C6-C20 arylcarbonyloxy, C1-C20 straight, branched or cyclic alkylsulfonyloxy, C6-C20 arylsulfonyloxy, C2-C20 straight, branched or cyclic alkoxycarbonyl, or C3-C20 straight, branched or cyclic alkoxycarbonylalkyl, X11 and X12 are each independently —O— or —CR72—, R7 is hydrogen or C1-C10 straight or branched alkyl, and j is 0 or an integer of 1 to 3,
• wherein R8 to R11 are each independently hydrogen or C1-C10 straight, branched or cyclic alkyl, X21 and X22 are each independently —O— or —CR122—, R12 is hydrogen or C1-C10 straight or branched alkyl, m is 0 or an integer of 1 to 3, R13 to R16 are each independently hydrogen or C1-C10 straight, branched or cyclic alkyl, X31 and X32 are each independently —O— or —CR172—, R17 is hydrogen or C1-C10 straight or branched alkyl, one of Y1 and Y2 is —(C═O)— and the other is —CR182—, R18 is hydrogen or C1-C10 straight or branched alkyl, and n is 0 or an integer of 1 to 3,
• at least one of X11, X12, X21, X22, X31, and X32 in the formulae is —O—.