US Patent 7173315 Semiconductor device

In a semiconductor device in which a control circuit region and a power transistor region are formed, a first dummy region is formed between a ground side transistor composing a push-pull circuit and the control circuit region while a second dummy region is formed between the ground side transistor and the end part of a semiconductor substrate. The first and second dummy regions have a conductive type different from that of the semiconductor substrate. The second dummy region is connected electrically to a part of the semiconductor substrate between the ground side transistor and the first dummy region.