Abstract: To provide a novel ABA-type triblock copolymer of vinyl ether series, comprising polyvinyl ether and an oxystyrene-series unit, and a process of producing the ABA-type copolymer at a series of steps. The invention relates to a novel ABA-type triblock copolymer comprising Segment A comprising an oxystyrene-series repeat unit (a) and Segment B comprising a vinyl ether-series repeat unit (b), in which the Segment A and the Segment B are bonded together with a single bond, and to a simple process of producing the same. The triblock copolymer can be produced at a series of steps in a simple manner, comprising living cationic polymerization of a vinyl ether-series monomer such as ethyl vinyl ether in the presence of a bifunctional initiator and a Lewis acid, and subsequently adding an oxystyrene-series monomer such as p-hydroxystyrene for living cationic polymerization.

Abstract: To provide a novel ABA-type triblock copolymer of vinyl ether series, comprising polyvinyl ether and an oxystyrene-series unit, and a process of producing the ABA-type copolymer at a series of steps. The invention relates to a novel ABA-type triblock copolymer comprising Segment A comprising an oxystyrene-series repeat unit (a) and Segment B comprising a vinyl ether-series repeat unit (b), in which the Segment A and the Segment B are bonded together with a single bond, and to a simple process of producing the same. The triblock copolymer can be produced at a series of steps in a simple manner, comprising living cationic polymerization of a vinyl ether-series monomer such as ethyl vinyl ether in the presence of a bifunctional initiator and a Lewis acid, and subsequently adding an oxystyrene-series monomer such as p-hydroxystyrene for living cationic polymerization.

Abstract: The positive photosensitive resin of the present invention has an acid-labile protecting group and the structure represented by the following general formula (1): (wherein X1 and X2 may be the sake or different and each independently a straight or branched chain hydrocarbon group, having 1 to 30 carbon atoms, an alicyclic hydrocarbon group or a heterocyclic group, which may substituted with straight or branched chain hydrocarbon of 1 to 6 carbon atoms or —O— hydrocarbon; Y1 and Y2 may be the same or different and are each independently a hydrogen atom, a straight or branched chain hydrocarbon group having 1 to 6 carbon atoms, a sulfur-containing hydrocarbon group, or an aromatic hydrocarbon group which may have a substituent; and two Zs may be the same or different and each independently an oxygen atom or a sulfur atom).

Abstract: The present invention provides a positive photosensitive resin and a resist composition containing the positive photosensitive resin, both of which are used for fine pattern formation in semiconductor production and are preferably used in a semiconductor lithography of higher-than-before sensitivity.