| 摘要 |
A semiconductor device comprises a semiconductor substrate having N- and P-channel regions formed therein; a plurality of first transistors formed in the N-channel region; a first field shield element-isolation structure having a first shield plate electrode and formed in the N-channel region for isolating the first transistors from each other; a plurality of second transistors formed in the P-channel region; and a second field shield element-isolation structure having a second shield plate electrode electrically connected to the first shield plate electrode and formed in the P-channel region for isolating the second transistors from each other; wherein respective values of a threshold voltage VtN of a parasitic transistor formed in a field region of the N-channel region, a threshold voltage VtP of a parasitic transistor formed in a field region of the P-channel region and a potential VsP of the first or second shield plate electrode are determined so as to meet VtN-VtP>Vcc-Vss and VtN>VsP-Vss>VtP+Vcc-Vss, where Vss is a potential of the source of the first transistor, Vcc is a potential of the source of the second transistor and Vcc>Vss. Further, a method for manufacturing a semiconductor device as above-mentioned wherein the surface impurity concentration of at least one of the P-channel region and the N-channel region is determined by a desired threshold voltage of the MOS transistor formed in that region.
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