Patent ID: 8455596
Filing Date: 2013-06-04
Classification: C08F

Abstract:
1. A method for production of a copolymer for photoresists, said copolymer containing at least two types of repeating units, said method comprising a supplying step of supplying a monomer solution and a solution containing a polymerization initiator into a polymerization reaction system, wherein the range of fluctuation of the monomer composition ratio of unreacted monomers is within the range between minus 15% and plus 5% in said polymerization reaction system during the period from the start of the polymerization reaction to the end of supplying of said monomer solution, and wherein the monomer composition ratio of said monomer solution at the start of supplying in said supplying step and/or the monomer composition ratio of said monomer solution fed in said polymerization reaction system in advance is determined by the procedures of said polymerization reaction comprising the following procedures (a) to (d): (a) supplying said monomer solution having a monomer composition ratio (II) identical or nearly identical to a production target composition ratio (X), and said solution containing said polymerization initiator into said polymerization reaction system, (b) measuring change with time of the composition ratio of said unreacted monomers in said polymerization reaction system, (c) determining a monomer composition ratio when said composition ratio measured in the procedure (b) is constant or nearly constant, and (d) employing the monomer composition ratio (I) determined in the procedure (c) as the monomer composition ratio of said monomer solution at the start of supplying in the above-mentioned supplying step, the monomer composition ratio of said monomer solution fed in said polymerization reaction system in advance.