| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of crystal defects and increase of a leakage current by providing a device forming region and a device isolating region on a principal surface of a semiconductor substrate and establishing a specific relationship among width of the device forming region, the amount of thermal oxidation in a trench of the device isolating region and radius of curvature at the lower end of the trench of the device isolating region. SOLUTION: A semiconductor device comprises a plurality of device forming regions and device isolating regions on a principal surface of a semiconductor substrate, and a trench is formed with radius of curvature R at the lower end by removing a portion of the semiconductor substrate where the device forming region is formed. The semiconductor substrate is then oxidized so that a relationship among trench radius of curvature R, the amount of trench thermal oxidation T (μm) and an active width of the device forming region (μm) becomes D<0.4<(-100> R<+7)-1> (-230T+14.5), and a thermal oxidation film is formed in the trench of the device forming region. Thereby, a generated stress can be the limit stress or less and prevent occurrence of crystal defects or increase of a leakage current.
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