Electron beam microprocessing method

An electron beam micro/nano fabrication method for allowing negative-tone lithography for irradiating, onto a surface of a GaAs thin layer formed on an AlxGayIn1-x-yAszP1-z (0≦x, y, z≦1) surface including GaAs alone or an LnP substrate, an electron beam controlled to an arbitrary electron beam diameter and current density so as to selectively substitute or generate Ga2O3 for a natural oxide layer formed on the GaAs surface, then dry-etching the GaAs layer surface by a bromide in single atomic layer units, and thereby selectively removing the natural oxide layer other than the part substituted by the Ga2O3, GaAs, and AlxGayIn1-x-yAszP1-z wherein

• an acceleration voltage of the electron beam is 50 keV or less and the amount of dose thereof is 1016 to 1020 electron/cm2, and
• microstructures having different aspect ratios can be formed by an identical step by controlling the amount of dose of an electron beam by controlling the amount to be etched at the time of dry etching by controlling the amount of irradiation of the electron beam and thereby generating Ga2O3 different in crystallinity on the GaAs layer surface.