The concept of blend resists in cross-linking negative resists is presented, and chloromethylstyrene-based blend resists are newly proposed on the basis of reaction mechanism. In chloromethylstyrene-based blend resists, almost the same sensitivity improvement as that for copolymer resists is obtained. Furthermore, the y value does not depend on the dispersivity of blend systems, but depends on the dispersivity of the higher molecular weight polymer with stronger electron donating ring-substituents. Based on this concept, a new class of blend resist, poly(p-methoxystyrene) (Mw = 1.1×105, Mw/Mn = 1.2) — poly(p-chloromethylstyrene) (Mw = 2.0×104, Mw/Mn = 1.3) [monomer unit ratio is 1:1] is demonstrated as a highly sensitive chloromethylstyrene-based resist. A high y value is obtained in spite of the broad dispersivity of the system, and submicron patterns are resolved at 3 μC/cm2.
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