| 摘要 |
A semiconductor structure includes a first high-voltage well (HVW) region of a first conductivity type overlying a substrate, a second HVW region of a second conductivity type opposite the first conductivity type overlying the substrate and laterally adjoining the first HVW region, and a third HVW region of the second conductivity type underlying the second HVW region. A region underlying the first HVW region is substantially free from the third HVW region, wherein the third HVW region has a bottom lower than a bottom of the first HVW region. The semiconductor structure further includes an insulation region in a portion and extending from a top surface of the first HVW region into the first HVW region, a gate dielectric extending from over the first HVW region to over the second HVW region wherein the gate dielectric has a portion over the insulation region, and a gate electrode on the gate dielectric.
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