| 摘要 |
PURPOSE:To provide the junction surface of a base and an emitter beneath a protecting film all the time, by forming a second layer, which is laminated on a first layer in a overhung state, introducing impurities in a substrate with the first layer having a larger opening area as a mask, and specifying an opening in the protecting film by the second layer having a small opening area. CONSTITUTION:On a first layer 22, which is laminated on a first conducting type semiconductor substrate 21, a second layer 23, whose physical property is different from the first layer 22 and which has an opening with a specified pattern, is formed. Then, with the second layer 23 as a mask, the first layer 22 is selectively etched and the surface of the semiconductor substrate 21 is exposed. An inner end part 26 of the second layer 23 is made to be an overhung state. With the first layer 22 as a mask, second conducting type impurities are introduced in the surface of the semiconductor substrate 21. An emitter region 27 and a protecting film 28 are formed. The surface of the exposed semiconductor substrate 21 is covered by a thin protecting layer 29. Said protecting layer 29 is etched, and an opening which is specified by the opening of the second layer 23, is formed in the protecting film 28. The surface of the semiconductor substrate 21, in which the impurities are introduced is exposed. |
