Phase shift mask blank, phase shift mask, and methods of manufacture

摘要

A phase shift mask blank includes a transparent substrate and a phase shift film composed primarily of a metal and silicon. The substrate has an etch rate A and the phase shift film has an etch rate B when the blank is patterned by reactive ion etching, such that the etch selectivity B/A is at least 5.0. When a phase shift mask is manufactured from the blank, the substrate is less prone to overetching, providing good controllability and in-plane uniformity of the phase shift in patterned areas. The phase shift mask can be used to fabricate semiconductor integrated circuits to a smaller minimum feature size and a higher level of integration.