| 摘要 |
PURPOSE: To provide MOS transistors of a SOI structure, wherein the MOS transistors can obtain a high driving capacity after obtaining a fully high threshold voltage. CONSTITUTION: Transistors 26 and 27 are constituted into a completely depleted transistor of a structure, wherein depletion layers under channel regions 25 reach a silicon oxide film 5. The film thickness of a silicon layer 1 forming the regions 25 is formed into a thickness of 0.1μm, which is equal with a value obtainable by subtracting the depth of grooves 22 from the depth of grooves 21. Accordingly, the threshold voltage of the transistors 26 and 27 can be set into a voltage of 0.5V or higher, which is required from the viewpoint of operation. Moreover, the film thickness of a silicon layer 1 forming source and drain regions 23 and 24 is formed into a thickness of 0.3μm, which is equal with the depth of the grooves 21. Accordingly, it becomes possible to reduce the sheet resistivity of the regions 23 and 24 and the driving capacity of the transistors 26 and 27 can be improved.
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