SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD FOR THE SAME

摘要

PURPOSE: A semiconductor device and a manufacturing method for the same are provided to manufacture the device wherein requirements for withstand voltage are met, allowable ON-state current can be increased, and output capacity and ON-state resistance can be reduced. CONSTITUTION: An n-type semiconductor layer(3) is formed on the insulating layer(2) on a semiconductor substrate(1). The n-type semiconductor layer(3) is formed so that an n++-type drain region(104) and a p+-type well region(105) are disposed apart from each other. In the p+-type well region(105), an n++-type source region(106) is formed. A gate electrode(109) is formed on an appropriate portion of the p+-type well region(105) with a gate oxide film(108) in-between. An n-type drift region(112) is formed between the n++-type drain region(104) and the p+-type well region(105). The distribution of the impurity concentration of the n-type drift region(112) is so set that the concentration is reduced both in the lateral direction and in the longitudinal direction of the n-type semiconductor layer(3) as it goes away from the n++-type drain region(104).