SEMICONDUCTOR DEVICE

摘要

PURPOSE: A semiconductor device is provided to simultaneously secure a breakdown voltage property and an operation current property by comprising an ion implantation region and a diffusion region on a deep well or buried impurity layer. CONSTITUTION: A second conductive deep well(73) is formed on a first conductive substrate. The second conductive deep well is comprised of a first ion implantation region and a first diffusion region. A first conductive type first well(76) is formed in the deep well to contact with the first diffusion region. A gate electrode(82) is formed on the substrate and crosses the first ion implantation region and the first diffusion region. A part of the first well is overlapped with one end of the gate electrode. The impurity doping density of the first diffusion region gradually decreases far away from the boundary surface of the first ion implantation region and the first diffusion region.