| 摘要 |
PROBLEM TO BE SOLVED: To provide such a transistor structure that can make a nonvolatile memory semiconductor device, having a flash memory section in which a memory transistor and a select transistor are formed and a logic section, in which a peripheral circuit transistor is formed on the same substrate to operate at high speed by suppressing the gate depletion, particularly in, the select transistor without making the processes complicated. SOLUTION: In a semiconductor device, a memory transistor is constituted by laminating a floating gate upon a control gate through a first insulating film, and at least the gate electrode of a select transistor is constituted into a single layer which contains impurities at increased concentrations by implanting ions into a polysilicon film, forming in the same layer as the floating gate electrode of the memory transistor in a source-drain area forming process.
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