ETCHING OF GALLIUM ARSENIDE BY OPTICAL PUMPING

PURPOSE:To mirror etching of a GaAs substrate, by disposing the GaAs substrate in a reactant gas comprising Cl2, and irradiating it with light having a peak in a wavelength range that pumps the Cl2 gas optically. CONSTITUTION:After the inside of an etching chamber 1 is evacuated, a stop valve 3 is opened to allow a predetermined flow of gas mixture consisting of Cl2 as a reaction gas and H2 as a diluent gas to flow into the etching chamber 1 through a gas inlet tube 4, while a flow of exhausted gas is regulated by means of a pressure regulating valve 5 such that the gaseous pressure within the etching chamber 1 is 50-100 torr. Subsequently, a GaAs substrate 14 is heated to 80-200 deg.C by a heater 13. The surface of the GaAs substrate 14 is then irradiated with ultraviolet rays from a high pressure mercury lamp having wavelength spectrum with a peak in the range of 400-455 nm, at an output of about 5-10 mW/cm . Thereby, the surface of the GaAs substrate 14 exposed from a m ask film 15 is etched.