| 摘要 |
PURPOSE:To improve yield by selectively oxidizing first and second poly crystalline semiconductor layers simultaneously and forming an electrode an a leading-out wiring for a transistor. CONSTITUTION:A buried layer 2 and an epitaxial layer 3 are shaped onto a semiconductor substrate 1, a thin oxide film 5 is formed onto the whole surface an an silicon nitride film 6 is shaped selectively, and collector, base and emitter regions are formed through selective oxidation, using the silicon nitride film as a mask. An silicon nitride film 11 and a thin oxide film 10 are removed, the surface of the epitaxial layer 3 is exposed, and a first polycrystalline semiconductor layer is shaped onto the whole surface. A base layer 8 is formed through selective ion implantation, a second polycrystalline semiconductor layer 15 is shaped onto the whole surface of the first polycrystalline semiconductor layer 13, and the first and second polycrystalline semiconductor layers are oxidized selectively at the same time to form an electrode and leading-out wirings 20, 21 for a transistor. Accordingly, the layer resistance of the wirings is lowered, and the yield of a semiconductor device can be improved largely.
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