SEMICONDUCTOR PATTERN FORMING METHOD

PURPOSE:To prevent a contaminated substance from being introduced into a device and enable pattern formation over a wide range to be performed in a short time by placing a semiconductor into oxygen environment, emitting laser interference light so that a specified grating pattern is formed on a surface of the semiconductor, and then selectively etching the surface of the semiconductor where light with a specified pattern was emitted using a reactive gas. CONSTITUTION:A substrate is moved into a chamber for forming an oxide film 202. Then, a highly pure oxygen is introduced into the chamber for forming an oxide film 202. In a light-emitting device, a laser beam 301 is divided into two portions by a beam splitter 302. One of the divided beam is reflected by a reflection mirror 305a and is emitted onto a substrate 307. The other beam impinges on a phase filter, the phase is adjusted so that interference fringes can be produced on the substrate surface, and then the beam impinges on the substrate 307. An etching gas 106 is introduced by an etching gas introducing device 207, thus enabling the substrate to be etched. As a result, grating is formed.