Patent ID: 7655743

Claim:
A process for producing an ArF excimer-laser photoresist polymer solution containing a polymer having: a repeated unit corresponding to at least one monomer selected from a monomer (a) having a lactone skeleton and a monomer (c) having an alicyclic skeleton having a hydroxyl group; and another repeated unit corresponding to a monomer (b) having a group which becomes soluble in alkali by elimination with an acid, the process comprising: (i) a polymerization step (A) of subjecting a mixture of monomers containing at least one monomer selected from the above monomers (a) and (c) and containing the monomer (b) to polymerization by a dropping polymerization method to obtain a polymer solution R; (ii) a precipitation purification step (C) of precipitating and purificating the polymer formed in the step (A) by separating the polymer from the polymer solution R to obtain a wet polymer; (iii) a redissolving step (G) of redissolving the wet polymer separated and purificated by the step (C) in an organic solvent to obtain a polymer solution S; and (iv) an evaporating step (H) of evaporating the organic solvent in the polymer solution S, wherein, by the evaporating step (H), a low-boiling-point solvent contained in the polymer solution S obtained by the redissolving step (G) is removed, and the polymer solution S is concentrated to prepare the photoresist polymer solution.