| 摘要 |
PURPOSE:To make a threshold voltage of MOSFET not to depend upon effective channel width by a method wherein an insulating film to be buried is made to rise higher than the surface of a substrate in a substrate region of element region, and moreover thickness of the risen part is set smaller than the thickness of the part to be buried. CONSTITUTION:An Si oxide film 7 buried in a field region is made to rise upward by the thickness t1 smaller than the part (thickness t2) buried under the surface position of a substrate of element region. Thickness t1+t2 of the whole of the film 7 is fixed to a constant, and when the ratio t1/t2 thereof is changed, changed quantity of effective channel width is desirable to be held in the range of 0.65<=t1/t2<1 when admissible error of + or -20mV is allowed in general at designing of an LSI. The MOSFET has no dependence upon effective channel width in this range.
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