| 摘要 |
PURPOSE:To form a tapering stepped portion simply and with excellent reproducibility, by inplanting impurities into a part near the surface of an insulating film to make different an etching rate in said part from the one in the other part, and by utilizing this difference in the formation of said portion. CONSTITUTION:The surface of a substrate 10 is covered with an insulating film 20, and impurities 30 such as PHOS<+> ions, for instance, are inplanted from the surface of the insulating film 20 so that a projection range is smaller than the size of the film thickness, in other words, the injection is concentrated on a part near the surface of said film. Then, the impurities 30 are activated by heat treatment. A resist 40 is connected on the surface of the insulating film 20 except a part thereof to be opened, and isotropic etching is applied with the resist 40 used as a mask. An etching rate is large in a region wherein the impurities 30 are inplanted, and thus etching progresses in the lateral direction as it proceeds in the direction of thickness. When the formation of an opening in the insulating film 20 is completed, a stepped portion 21 tapering at a prescribed angle is formed. |
