Semiconductor device and method of manufacturing semiconductor device

摘要

A diffusion diode including a p+ diffusion region, a p-type diffusion region, and an n+ diffusion region is formed in the front surface of a semiconductor substrate. A polysilicon diode including a p+ layer and an n+ layer is formed on top of a local insulating film formed on the front surface of the semiconductor substrate and faces the diffusion diode in the depth direction. The diffusion diode and the polysilicon diode are reverse-connected by electrically connecting the n+ diffusion region to the n+ layer, thereby forming a lateral protection device. The p+ layer and p+ diffusion region are respectively electrically connected to a high voltage first terminal and a low voltage second terminal of the lateral protection device. The polysilicon diode blocks a forward current generated in the diffusion diode when the electric potential of the first terminal becomes lower than the electric potential of the second terminal.

主权项

1. A semiconductor device, comprising:
a semiconductor substrate of a first conductivity type; a first semiconductor region of a second conductivity type that is selectively formed in a surface layer of a front surface of the semiconductor substrate; a second semiconductor region of the first conductivity type that is selectively formed in the first semiconductor region; a third semiconductor region of the second conductivity type that is selectively formed in the first semiconductor region and separated from the second semiconductor region and that has a higher impurity concentration than the first semiconductor region; a fourth semiconductor region of the first conductivity type that is selectively formed on the front surface of the semiconductor substrate with an insulating film interposed therebetween, said fourth semiconductor region being made of a polycrystalline silicon layer; a fifth semiconductor region of the second conductivity type that is selectively formed on the front surface of the semiconductor substrate with said insulating film interposed therebetween, said fifth semiconductor region being made of a polycrystalline silicon layer that contacts the fourth semiconductor region; a first electrode that contacts the second semiconductor region and the fourth semiconductor region; a second electrode that contacts the third semiconductor region; and a third electrode that contacts the fifth semiconductor region, wherein the first semiconductor region faces the fourth semiconductor region and the fifth semiconductor region in a depth direction.