| 摘要 |
PROBLEM TO BE SOLVED: To improve controllability and stability of the threshold voltage of an MOS transistor and the resistance value of a polysilicon resistor. SOLUTION: A thermal oxide film 39 is formed on the surfaces of N+ poly- NMOS 27, N+ poly-PMOS 29, P+ poly-PMOS 31, and the polysilicon resistor. A silicon nitride film 41 is formed on the thermal oxide film 39 except the formation areas of the N+ poly-PMOS 29 and P+ poly-PMOS 31. The thermal oxide film 39 cuts off diffusion of hydrogen during the formation of the silicon nitride film 41 to improve, specially, the threshold stability of the P+ poly- PMOS 31, the threshold voltage stability of the N+ poly-NMOS 27, and the resistance value stability of the polysilicon resistor 35. The silicon nitride film 41 cuts off the diffusion of hydrogen during the formation of upper-layer films to improve, specially, deterioration in the hot-carrier resistance of the N+ poly-NMOS 37 and the controllability and stability of the resistance value of the polysilicon resistor 35.
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