| 摘要 |
PURPOSE:To form a peripheral circuit without increasing its resistance by forming MISFET having source, drain regions of the minimum necessary occupying area and MISFET having source, drain regions as the conventional one on the same substrate to prevent, for example, the influence of alpha-ray from occurring in a memory cell of RAM. CONSTITUTION:An address film 29 and a nitride film 19 of a self-aligning FET are sequentially removed by etching, SiO2 films 16 not masked with a polysilicon pattern 17a are etched in both its portion and non-self-aligned FET, and oxidized to form an SiO2 film 20. Then, since the oxidizing speed of the doped polysilicon is larger than the single crystal silicon, the thickness of an oxide film on the gate electrode 17a becomes larger than the oxide film formed on a substrate formed with source, drain diffused regions. When the SiO2 film on the substrate is etched, an SiO2 film 20a remains around the electrode 17a. Reverse conductivity type impurity is ion implanted to the exposed substrate to form source, drain diffused regions 21, 22, a polysilicon layer 23 is patterned to form electrodes 23, 24.
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