| 摘要 |
After a polycrystalline Si layer is deposited on an insulating film covering the surface of a semiconductor substrate, a mask layer having a desired pattern is deposited on the polycrystalline Si layer. Using the mask layer as an etching mask, the polycrystalline Si layer is dry-etched by a plasma etching process. In the plasma etching process, a metal halide (such as AlCl3 and AlBr3) gas is introduced in an etching reaction chamber, or Al halide is generated by reacting halogen (Cl, Br or the like) contained in an etching gas with Al constituting the inner wall of the etching reaction chamber or an electrode. The etching process is performed while attaching an Al halide film to the etched side walls of the polycrystalline film. The polycrystalline Si film is etched in a taper shape becoming thicker at the lower portion. The Al halide can be removed easily.
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