HIGH WITHSTAND VOLTAGE SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD OF HIGH WITHSTAND VOLTAGE SEMICONDUCTOR DEVICE

摘要

A high withstand voltage semiconductor device and a manufacturing method of the same are provided to suppress the variation of Vt by preventing plasma damage in a via hole forming process. A gate electrode(17) of a transistor includes a gate insulating layer(16). The gate insulating layer is formed on a semiconductor substrate. The gate insulating layer has a thickness of 350 angstrom or more. A first conductive type well region is formed on a surface area of the semiconductor substrate. A second conductive type diffusion layer(20) is formed on the well region of the surface area of the semiconductor substrate. A diode is composed of the first conductive type well region and the second conductive type diffusion layer. The diode is electrically connected by using a wiring directly connected through contacts.