| 摘要 |
PURPOSE: A semiconductor is provided to control easily the thickness of a number of gate oxides and to improve the integrity, to improve the flatness in multi layer wiring and to prevent the short channel effect. CONSTITUTION: A semiconductor device includes: a P type semiconductor substrate(31); a first field oxide(37) formed in a first trench(33) defining a first and second transistor region(T21,T22) on a field region(F21) of a device of the semiconductor substrate; a second field oxide(45) formed in a second trench(35) formed on a part including a part of the first and second transistor region on top of the first field oxide; a third trench(47,48) formed on the first and second transistor region of the second field oxide; a first and second gate oxide formed between a side of the third trench and a side of the second trench; a first and second gate(53,55) formed in the third trench formed on the first and second transistor region respectively; a first impure region(39,40) formed on a part where the second trench of the semiconductor substrate is not formed; and a second impure region(42,43) formed on a part where the second trench of the semiconductor substrate is not formed.
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