| 摘要 |
A semiconductor device has a dielectric strength for a gate oxide film at a trench bottom that is higher than that of side walls used for channels. An n+0 type substrate 1 having substrate plane orientation of (110) is prepared, and the side walls of a trench where channels are formed are in (100) planes. The other, non-channel forming, side walls of the trench are in (110) planes. Thus, the growth rate of the gate oxide film 7 in the non-channel forming side walls and the trench bottom is faster than that in the channel forming side walls. As a result, the film thickness at the non-channel-forming side walls and the trench bottom is greater than that of the channel-forming side walls. Accordingly, the device has high mobility, and there is no drop of dielectric strength due to partial reduction of the thickness of the gate oxide film 7. This achieves both a reduction of the ON resistance and an increase in the dielectric strength of the semiconductor device.
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