Method and apparatus for dry-etching half-tone phase-shift films, half-tone phase-shift photomasks and method for the preparation thereof, and semiconductor circuits and method for the fabrication thereof

Abstract

A chromium-containing half-tone phase-shift photomask comprising coarse and dense patterns coexisting in a plane is prepared by a series of pattern-forming steps including forming a resist layer on a photomask blank, exposing and patterning said resist layer, developing, etching said photomask blank and removing said resist layer. Patterns for transferring onto a wafer are formed on the photomask blank by a dry-etching method comprising dry-etching a chromium-containing half-tone phase-shift film utilizing etching gas comprised of mixed gas including (a) reactive ion etching gas, containing an oxygen-containing gas and a halogen-containing gas, and (b) reducing gas added to the gas component (a).