WORKING OF ZINC OXIDE FILM

PROBLEM TO BE SOLVED: To enhance the working precision, to accelerate etching rate and to solve the problems of corrosiveness and toxicity by using a process gas contg. methane at the time of dry etching treatment of a film formed on a substrate. SOLUTION: An SiO2 layer 2 is formed on the surface of a silicon substrate 1 by a thermal oxidation method, and a ZnO film 3 is formed on the SiO2 layer by a magnetron sputtering method. Al is vapor-deposited on the ZnO film 3 to form Al electrically conductive film 5, a resist 6 is applied on the surface, and the resist 6 is patterned by an electron beam plotting method. Then, an electrically conductive film 5 is etched, the resist 6 is peeled, and the ZnO film 3 is dry-etched by using a reactive ion etching device. As a process gas for the dry etching, a gaseous mixture of methane and argon is used. The mixing ratio of methane is controlled in the range of 2 to 8 mol.%. The etching rate of ZnO is about 100 Angstron/min, and the etching rate of Al is about 0 Angstron/min.