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...http://www.google.ca/patents/US7001698?utm_source=gb-gplus-sharePatent US7001698 - 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
