| abstract |
PURPOSE:To improve dimensional precision by forming a thin film layer having etching resistance on a mask base material having etching resistance, forming a resist pattern on the thin film, etching it, and repeating the second etching. CONSTITUTION:A polymethyl methacrylate film 14 is formed on the thin film 13 made of tantalum, and exposed to electron beams in a desired pattern, and then, developed with isoamyl acetate to form a resist pattern 14. Further, the thin film 13 is selectively removed by using the resist pattern 14 as a mask and the reactive ion etching, and the reactive ion etching process is repeated by using a gas mixture of carbon tetrachloride and oxygen to remove chromium 12, thus permitting the thin tantalum film to effectively work as the mask of the chromium film 12 underlying the film 13, though the resist pattern 14 is gradually removed. |