| 摘要 |
PROBLEM TO BE SOLVED: To enhance the characteristics of an HBT.SOLUTION: When forming a laminated film consisting of silicon films 15a, 15b on an insulating film 14 formed on a collector layer 13, the silicon film 15a having an impurity concentration lower than that of the silicon film 15b is formed on the insulating film 14, and then the silicon film 15b is formed thereon. Subsequently, the back surface of the silicon film 15a in the laminated film is exposed, and an opening OA2 for exposing the surface of a collector layer 13 is formed. In this state, the back surface of the silicon film 15a and the front surface of the collector layer 13 are cleaned. Here, exposure of the silicon film 15b having a high impurity concentration above the opening OA2 can be avoided. Consequently, contamination of the collector layer 13 exposed to the bottom of the opening OA2 with impurities can be reduced, and the characteristics of an HBT can be enhanced. |
