| 摘要 |
PURPOSE:To eliminate unevenness of impurity ion concentration and form a diffused layer with a uniform depth by a method wherein, after impurity ion implantation is applied through a polycrystalline silicon layer formed only in a diffusion window with a uniform thickness, a heat treatment is carried out. CONSTITUTION:After an emitter diffusion window 7 is formed in an oxide film 6, a nondoped polycrystalline silicon layer 8 is formed over the whole surface. A resist 10 is applied over the whole surface. The resist 10 and the silicon layer 8 are successively etched by reactive ion etching to form a polycrystalline silicon layer 8b in the diffusion window 7. After impurity ion implantation is applied over the whole surface, a heat treatment is carried out to form an N<+> type emitter region 11b. As the silicon layer 8b of an emitter junction is formed in the diffusion window 7 with a uniform thickness, the film thickness of the region 11b is also uniform. With this constitution, unevenness of impurity ion concentration can be formed with a uniform thickness.
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