Patent ID: 7488429

Claim:
A method of dry etching, comprising: a mask layer forming step of forming a main mask layer and a sub mask layer in this order over a to-be-etched layer; a sub mask layer processing step of processing the sub mask layer into a predetermined concavo-convex pattern; a main mask layer processing step of removing parts of the main mask layer under concave portions of the concavo-convex pattern by reactive ion etching using at least either one of oxygen and ozone as a reactive gas; and a to-be-etched layer processing step of removing parts of the to-be-etched layer under the concave portions of the concavo-convex pattern by dry etching, thereby shaping the to-be- etched layer into the concavo-convex pattern, wherein the main mask layer is made of a material in which a ratio of a number of carbon atoms to a total number of atoms constituting the material of the main mask layer is 70% or more, the sub mask layer is made of a material selected from the group consisting of Ni, Ta, Ti, Si, TaSi and mixtures thereof, and the sub mask layer has an etching rate lower than that of the material of the main mask layer with respect to the reactive ion etching in the main mask layer processing step.