| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alternating copolymer useful for e.g. a base polymer of a chemically amplified resist material, which copolymer is made from 4-(1- methylethenyl)phenol and (meth)acrylic acid or an ester thereof, has specified or higher contents of the monomers, and has a specified or higher transmittance to light at a specified wavelength. SOLUTION: There is provided an alternating copolymer comprising formula I and formula II, having a content of repeating units of formula III of at least 75 mol.% and having a transmittance of at least 90%/μm to light at wavelength of 350 nm. In the formulae, R1 is H or methyl; R2 is H or a 1-20C linear, branched or cyclic substituted or unsubstituted alkyl. This copolymer is obtained by heating (A) 4-(1-methylethenyl)phenol, (B) a (meth)acrylic acid (ester) of formula IV, (C) a radical polymerization initiator, (D) a phenol compound of formula V, and (E) a solvent to 50-150 deg.C in such a mixing ratio that the molar ratio of component A to component B is 3.5:6.5 to 6.5:3.5, the molar ratio of the total of components A and B to component C is 1:0.0001 to 1:0.1, and the amount of component D is 0.1-1,000 ppm based on the total amount.
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