Mask blank and method of manufacturing an imprint mold

摘要

Provided is a method of manufacturing an imprint mold formed with a highly accurate fine pattern by the use of a mask blank. In a mask blank having a thin film for forming a pattern on a transparent substrate, the thin film comprises an upper layer formed of a material containing Cr and nitrogen and a lower layer formed of a material containing a compound mainly composed of Ta and capable of being etched by dry etching using a chlorine-based gas. The upper layer and the lower layer of the thin film are etched by dry etching using a chlorine-based gas substantially free of oxygen and then the substrate is etched by dry etching using a fluorine-based gas, thereby obtaining an imprint mold.