| 摘要 |
PROBLEM TO BE SOLVED: To reduce defects of breakdown strength in a trench-type semiconductor device of a structure, with a trench being formed in a semiconductor substrate and a current path being provided on the sidewall of the trench and under the bottom of the trench. SOLUTION: A trench-type semiconductor device is constituted in a structure that a first trench is etched in a semiconductor substrate from a protecting film on the surface of the substrate, A CVD oxide film is formed on the sidewall of the first trench, a second trench is etched in the substrate along the first trench and after the trenches are treated with a hydrofluoric acid-containing solution, isotropic etching is performed on the trenches, the sidewall of the lower-stage trench and the surface of the CVD oxide film within the upper-stage trench are made to be flush with each other, and each singular point of a gate oxide film and gate electrodes is eliminated. |
