| 摘要 |
PURPOSE:To improve the manufacturing yield and the reliability of a semiconductor device by forming by self-aligning inner and outer bases by utilizing the difference of etching rate of KOH between a polysilicon doped in P<+> type and a polysilicon not doped, and enabling to readily remove a polysilicon layer used to form a window used for diffusion to form the inner base. CONSTITUTION:A photoresist film 27 is removed with KOH, and polysilicon which is disposed under the film and not doped is removed. Then, polysilicon is thermally nitrided to form a nitrided film 26a, an oxidized film 25 is etched with the film 26a as a mask, thereby forming windows E, B. Subsequently, the film 26a is removed with phosphoric acid. Thereafter, a polysilicon layer 27 which is not doped is grown on the overall surface, an inner base 28 and a base contact 29 are formed by through diffusion using the windows E, B through the layer 27, and an emitter 30 is formed by double diffusion using the same window E. In other words, since the emitter diffusion is performed without any alteration of the pattern as it is from the window E formed with the base 28, a possibility of displacing the position can be entirely eliminated. |
