A method for manufacturing a semiconductor circuit which comprises the steps of transferring the patterns formed on the chromium-containing half-tone phase-shift photomask, being prepared by performing a series of pattern-forming steps including a step for forming a resist layer on a photomask blank, a step for exposing and patterning said resist layer, a developing step, a step for etching said photomask blank and a step for removing said resist layer, wherein the photomask is characterized in that patterns to be transferred onto a wafer are formed on said photomask blank for the chromium-containing half-tone phase-shift photomask according to a dry-etching method comprising dry-etching a metal thin film as a chromium-containing half-tone phase-shift film, wherein the method is characterized by reducing the dimensional difference due to the coexistence of coarse and dense patterns within a plane, wherein by using, as an etching gas, a mixed gas including (a) a reactive ion etching gas, which contains an oxygen-containing gas and a halogen-containing gas, and (b) a reducing gas added to the gas component (a), in the process for dry-etching the metal thin film, wherein said metal thin film is a chromium-containing half-tone phase-shift film consisting of a chromium film, a chromium oxide film, a chromium nitride film, chromium oxynitride film, chromium fluoride film or a laminated film thereof, to manufacture the semiconductor circuit which comprises coexisting coarse and dense patterns corresponding to said resist patterns, wherein a relative flow rate of the mixed gas used consists of, by volume of mixed gas, one of:
- chlorine, oxygen and hydrogen gases from 66 to 46%, 17 to 11%, and 18 to 41%, respectively;
- and
- chlorine, oxygen and hydrogen chloride gases from 58 to 44%, 15 to 11%, and 28 to 45%, respectively.