| 摘要 |
PURPOSE:To prevent overetching and to obtain a photomask blank capable of being patterned with high precision suitable for fabricating semiconductors, etc. by forming a chromium oxide layer higher in oxidation degree on the side near a transparent substrate and lower on the other side on said substrate. CONSTITUTION:Chromium is vapor-deposited on the precisely polished surface of a transparent glass substrate 10 first in an atm. of 85:15-70:30 gaseous Ar/ gaseous O2 ratio rich in O2 by the sputtering method or the like to form a layer 22 rich in oxidation degree. Then, a layer 23 lower in oxidation degree is formed by reducing a gaseous O2 content to 95:5-100:0 Ar/O2 ratio. This method makes the etching speed of the film 22 higher than that of the film 23, and a photoresist pattern is formed on the film 23 and subjected to etching, and for example the films 22, 23 are left by the presence of foreign matters, and further they are etched. At that time, overetching is prevented and deterioration of dimensional precision is avoided. |
