Patent ID: 8421153
Filing Date: 2013-04-16
Classification: H01L

Abstract:
1. A semiconductor device, comprising: a semiconductor substrate; an element region formed on the semiconductor substrate, and including an MOS transistor formed thereon; an element termination region formed on the semiconductor substrate and formed at an end region of the element region; a first semiconductor layer of a first conductivity type formed to extend in a first direction as its lengthwise direction from the element region to the element termination region, the first semiconductor layer having a first impurity concentration, the first semiconductor layer functioning as a drain region of the MOS transistor in the element region; a second semiconductor layer of the first conductivity type formed to extend in the first direction as its lengthwise direction from the element region to the element termination region, the second semiconductor layer being formed in a layer below the first semiconductor layer, the second semiconductor layer having a second impurity concentration that is smaller than the first impurity concentration; a third semiconductor layer of the first conductivity type formed to extend in the first direction as its lengthwise direction from the element region to the element termination region, the third semiconductor layer having a third impurity concentration that is smaller than the second impurity concentration, the third semiconductor layer being arranged in contact with the second semiconductor layer to function as a drift layer of the MOS transistor; a field oxide film formed on a surface of the third semiconductor layer and in contact with the first semicondutor layer; a fourth semiconductor layer of a second conductivity type formed on the semiconductor layer to extend in the first direction as its lengthwise direction from the element region to the element termination region, the fourth semiconductor layer functioning as a channel region of the MOS transistor in the element region; a fifth semiconductor layer of the first conductivity type formed on a surface of the fourth semiconductor layer and functioning as a source region of the MOS transistor; and a gate electrode formed on a surface of the semiconductor substrate between the third semiconductor layer and the fourth semiconductor layer, via a gate insulating film, a distance between a boundary between the first semiconductor layer and the field oxide film, and the end portion of the third semiconductor layer on the side of the fifth semiconductor layer in the element region is smaller than a distance between a boundary between the first semiconductor layer and the field oxide layer and an end portion of the third semiconductor layer on the side of the fifth semiconductor layer in the element termination region.