| 摘要 |
PROBLEM TO BE SOLVED: To suppress fluctuation of the capacitance value of a capacitance element by coating the upper surface of the element with a polysilicon layer for diffusing emitter. SOLUTION: After an N-type epitaxial layer is formed on a P-type substrate 11, an island region is isolatedly formed. A lower electrode region 19 is formed in the island region, and an opening is formed in the insulating film overlying the region 19. Then a dielectric thin film 27, which covers the opening and the surface of the polysilicon resistor 25, is formed. In addition, each diffusion region, contact holes, and polysilicon electrodes 31-34 are formed. The electrode 31 is formed as a diffusing-source film for emitter diffusion, and the electrode 34 becomes part of the upper electrode of a capacitance element and works to protect the dielectric thin film 27. Since the thin film 27 can avoid being exposed to an etchant, the variation of the thin film 27 can be suppressed.
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