| 摘要 |
PURPOSE:To facilitate forming an island of a polycrystalline silicon film which covers an emitter window perfectly without applying mask alignment by a method wherein a bowl shape recess is formed in a silicon oxide film through an aperture in a silicon nitride film formed on it and an aperture, which has the same shape as the aperture in the silicon nitride film, is formed at the bottom of the recess and polycrystalline silicon is evaporated. CONSTITUTION:A silicon oxide film 8 is formed on a semiconductor substrate 6 and 7 and a silicon nitride film 9 is formed on the silicon oxide film 8 by evaporation. Then an aperture is made in the silicon nitride film 9 by lithography and a bowl shape recess including side etched part under the silicon nitride film 9 is formed through the aperture. Then an aperture which has the same shape as the aperture in the silicon nitride film 9 is formed at the bottom of the bowl shape recess in the silicon oxide film 8 and polycrystalline silicon is evaporated to form a polycrystalline silicon film 11 into an island shape which covers a part of the aperture of the silicon oxide film 8 and a part of the bowl shape recess. After that, for instance, an emitter region 12 is formed by impurity diffusion from the polycrystalline silicon film 11 and further a base contact window 13 is formed to form a graft base region 14.
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