| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device, that mixedly mounts a two-layer polysilicon capacity element with small voltage dependence and a MOS transistor with small threshold fluctuation. SOLUTION: A LOCOS film 7 is formed (A), a sacrificial oxide film 29 and a silicon nitride film 30 are formed (B), a polysilicon film 31 is deposited (C), the silicon nitride film 30 prevents phosphor from diffusing into a MOS transistor region, and at the same time, the phosphor is introduced to the polysilicon film 31 with high concentration, and a lower electrode 31a is formed by a polysilicon film 31 (D). The silicon nitride film 30 is removed, impurities for controlling threshold are injected into the MOS transistor region across the sacrificial oxide film 29, the sacrificial oxide film 29 is removed (E), an interlayer insulating film 33 and a silicon oxide film 35 are simultaneously formed (F), a polysilicon film 37 is deposited on them (G), and an upper electrode 37a and a gate electrode pattern 37b are formed simultaneously by the polysilicon film 37.
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