Hemiacetal esters and acetals derived from an alkyl vinyl ether are useful for chemical amplification type resist compositions, synthetic intermediates of pharmaceuticals, paints, or the like, because leaving of a group derived from the alkyl vinyl ether by heat, an acid catalyst or the like easily occurs. For example, use of hemiacetal esters and acetals, which are derived from an alkyl vinyl ether, in a chemical amplification type resist composition has been known (Japanese Published Unexamined Patent Application No. 2000-298344 and the like). Hemiacetal esters and acetals derived from an alkyl vinyl ether are generally produced by allowing of an alkyl vinyl ether to react with a compound having a carboxyl group or the like in the presence of an acid catalyst or the like. However, for example, when an ethyl vinyl ether or the like is allowed to react with a compound having a carboxyl group or the like, there has been a problem that a byproduct such as a polymer of the ethyl vinyl ether or the like is produced. In addition, when a polymer comprising a carboxyl group, which has been subjected to hemiacetal esterification using an ethyl vinyl ether, is used in a chemical amplification type resist composition, stability of the hemiacetal ester is inferior in a prebaking step conducted for the purpose of removing an organic solvent used upon spin coating of the polymer on a silicon wafer, or during storage for a long period of time. Thus, the polymer was also unsatisfactory for practical use.
Further, synthesis of a hemiacetal ester was studied in Journal of Adhesion Society of Japan, vol. 34, p. 246 (1998), in which a reaction between a straight chain alkyl vinyl ether and a compound having a carboxyl group was performed in the presence of various kinds of acids. However, in the presence of an acid other than phosphoric acid (hydrochloric acid, sulfuric acid, nitric acid), the result was that the yield was low and a large number of polymers, which are byproducts, derived from the alkyl vinyl ether was produced.
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