| 摘要 |
PURPOSE:To reduce the areas of an emitter and an internal base by injecting an impurity in a base leading-out section against a residual pattern in the internal base section by utilizing a transverse diffusion and conducting etching corresponding to an impurity profile. CONSTITUTION:A residual pattern 17 is formed onto a silicon substrate 11, a polysilicon film 18 and a nitride film 19 are grown on the whole surface, and patterned in width of approximately 2.0mum so as to surround the pattern 17, leaving a resist film 20 and so as to mask sections except a base leading-out section 18a for the polysilicon film 18, and the ions of a metal such as boron (B<+>) are implanted. When etching is conducted by KOH, polysilicon not doped by B<+> on the residual pattern 17 is etched, and B<+>-doped polysilicon (the base leading-out section 18a) is not etched and left. Accordingly, when an SiO2 film in the residual pattern 17 is removed and an internal base 21a and an emitter 26 are shaped, the width of the emitter 26 is brought to a size obtained by subtracting the film thickness of an SiO2 film (wall thickness) 25 from the width 1.0mum of the residual pattern.
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