Method of manufacturing semiconductor device.

摘要

According to a method of manufacturing a high-frequency bipolar transistor, a p-type base region (2) is formed on an n-type silicon substrate (1). A first oxide film (3) and a nitride film (4) are formed on the base region (2). A base contact hole is formed by etching, and a first polysilicon film (6) containing a p-type impurity and serving as a base electrode (6) is formed thereon. A second oxide film (7) having a thickness larger than that of the first oxide film (3) is formed by thermal oxidation around the base contact hole to surround the first polysilicon film (6). A portion of the nitride film (4) which is not covered with said second oxide film (7) and a portion of the first oxide film (3) therebelow are removed by etching to form an emitter contact hole. A second polysilicon film including an n-type impurity and serving as an emitter electrode (10) is formed in the emitter contact hole. The n-type impurity in the second polysilicon film (10) is diffused in the substrate by annealing to form an n-type emitter region (11). In the completed bipolar transistor, the base electrode (6) and the emitter electrode (10) are insulated from each other by the second oxide film (7).