| 摘要 |
PURPOSE:To enable the protection of a surface facing an opening of a semiconductor substrate by a method wherein an oxide film formed on the surface in the opening of the semiconductor substrate is removed, an oxidation resisting film is formed thereafter on the surface facing the opening of the semiconductor substrate, and then the inside surface of the opening is oxidized to form an oxide film. CONSTITUTION:A polycrystalline silicon layer 2 and a silicon oxide film 3 are formed on an N-type semiconductor substrate 1, and an opening 4 for forming a base region is formed by etching. Thereafter P-type impurities are ion-implanted into the surface of the semiconductor substrate 1 through the opening 4, so as to form the base region 5. When the surface of the semiconductor substrate 1 is heat-oxidized subsequently, an oxide film 6 is formed on the inside surface of the opening 4 of the polycrystalline silicon layer 2 and on the surface of a part facing the opening 4 of the semiconductor substrate 1. Then, the part of the silicon oxide film 6 formed on the surface of the semiconductor substrate 1 is removed by anisotropic etching, a silicon nitride film 7 is formed on the surface of the semiconductor substrate 1, and a side wall 8 is formed on the inside surface of the opening 4 of the polycrystalline silicon layer 2. Accordingly, it can be avoided that the surface of the semiconductor substrate is damaged by anisotropic etching.
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