| 摘要 |
PURPOSE:To obtain a fine bored window by forming a mask containing an Si3N4 film onto a poly Si layer on an Si substrate, introducing and oxidizing an impurity and removing an impurity non-introducing section by a formed oxide-film mask. CONSTITUTION:An n<-> Si substrate 10 is isolated by an oxide film 12, poly Si 20, a thermal oxide film 21, and a CVDSi3N4 mask 22 are superposed, a photo-resist 23 is left on an emitter forming region, and the side surface of the Si3N4 22 is etched preferentially by selecting conditions. B<+> ions are implanted by 10<20>/cm<3> or more. When the resist 23 is removed and the remainder is oxidized, SiO2 25 is formed while an impurity is activated, the window of the film 25 is made narrower than a window by lithography accuracy, an emitter window is shaped on the inside of an ion implanting boundary 20a, and a section between an external base and an emitter is narrowed. Si3eN4 22 and SiO2 21 are etched by HF and SiO2 25 by KOH, a non-adding section 20b is removed preferentially, the surface is coated with CVDSiO2 28, films 26, 28 are left on the side wall of the window through PIE, and an internal base 30 and the emitter are formed. According to the constitution, the fine emitter window is obtained, and base-collector capacitance can be reduced. |
