Patent ID: 7923807
Filing Date: 2011-04-12
Classification: H01L

Abstract:
1. A synchronous buck DC-DC converter comprising: a semiconductor substrate of a first conductivity type; a first line supplying a first voltage; an inductor element; a second line supplying a second voltage lower than the first voltage; a first switching element formed on the semiconductor substrate and connected between the first line and one end of the inductor; a second switching element formed on the semiconductor substrate and connected between the one end of the inductor and the second line; a controller formed on the semiconductor substrate and configured to control the conduction of the first and second switching elements; and a first trench formed on the semiconductor substrate to electrically separate the second switching element from the first switching element and the controller, the second switching element further including: a well layer of the first conductivity type selectivity formed on the semiconductor substrate; a first diffused layer of a second conductivity type selectivity formed on the well layer; a second diffused layer of the second conductivity type formed on the well layer apart from the first diffused layer; a control electrode formed on an insulating film between the first diffused layer and the second diffused layer; and a main electrode formed on each of the first diffused layer and the second diffused layer, the first trench further including a third diffused layer of the second conductivity type formed contacting to the first trench, the second diffused layer and the third diffused layer being electrically kept at the same potential.