| 摘要 |
PURPOSE:To reduce the irregularity in a base contact width and to achieve a high integration density by a method wherein a microscopic opening with a prescribed width is made at the upper part of a single-crystal protruding region, a base electrode is pulled out from this opening and a microscopic groove whose cross section is U-shaped is formed in the circumference of an active region. CONSTITUTION:Firstly, a method to form a base contact part is explained. The surface of a P-type silicon substrate 1 is oxidized and an oxide film 17 is formed; furthermore, a silicon nitride film 18 and an oxide film 19 are deposited. Then, after the silicon nitride film 18 has been side-etched, polycrystalline Si 23 is deposited; lastly, an emitter region and a base region are formed; a structure which makes use of the polycrystalline Si film 23 as a base extraction electrode is completed. In the next step, a method to form a microscopic U-shaped groove is explained. As follows: the surface of a silicon substrate 1 is oxidized; an oxide film 25 is formed; silicon nitride 26 is deposited. After that, the microscopic U-shaped groove is formed in the semiconductor substrate by using a dry etching technique. Then, the oxide film 25 is formed inside said groove. By this setup, it is made possible to control a contact width of a base extraction part microscopically and with good accuracy; in addition, an integration density is more than doubled thanks to the microscopic U-shaped groove.
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