Patent ID: 9704946
Date: 2017-07-11
CPC Classifications: H01L

Claim:
1. A semiconductor device including a diode, comprising: a semiconductor substrate of a first conductivity type having a first main surface and a second main surface opposite to each other; an anode of a second conductivity type formed on said first main surface side of said semiconductor substrate; a guard ring formed at a distance from said anode and surrounding said anode; a cathode including a high-concentration impurity layer of the first conductivity type formed on said second main surface side of said semiconductor substrate; a cathode-side impurity region of the second conductivity type formed in a region located in said cathode and opposite to said guard ring; a cathode electrode connected to said cathode; an ultrahigh-concentration impurity region located between said cathode electrode and said cathode-side impurity region; said cathode-side impurity region is electrically floating with respect to said cathode electrode; and said cathode-side impurity region extends continuously in a direction away from a region facing said anode and does not extend to be opposite said anode, and forms an interface with the high-concentration impurity layer of the cathode.