| 摘要 |
PURPOSE:To easily form a microscopic groove by a method wherein, after a groove has been formed on the second layer in such a manner that a part of the surface of the first layer will be exposed, the third layer is formed on the surface, and then the third layer is left on the side wall of the groove on the second layer by performing an overall etching on the third layer. CONSTITUTION:After a low density silicon layer 12 has been laminated on a semiconductor substrate 11, a silicon dioxide film 13 is laminated on the layer 12. Then, a window to be used for base diffusion is formed using a lithographic technique, and the base region B having the prescribed width is formed in the layer 12 by diffusing impurities. Subsequently, a groove 14 having the prescribed width is formed in the region B of the film 13 using a mask having the prescribed pattern, and a part of the surface of the layer 12 is exposed. Then, after a silicon nitride film 15 has been grown on the whole surface, the film 15 is removed by performing an anisotropic etching, and the film 15 is left on the side wall part only of the groove 14. Subsequently, an emitter region E is formed and it is used as the emitter region of a high frequency bipolar transistor.
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