Semiconductor with high surface breakdown voltage - has boron implanted channel between base and channel stopper zones of different conductivity

摘要

Semiconductor device in which Boron implantation of the surface layer has been used to increase the breakdown voltage. A channel (4) with a relatively smaller depth is formed by Boron implantation between two end zones (2,3) which are respectively a p conducting base an n-conducting channel stopper. A covering oxide layer (5) with an increased thickness (d) 0.7 mmicrons over the channel is subjected to an accleration voltage of 150 keV to achieve a doping maximum in the border area between oxide layer (5) and substrate (1). The Boron implantation level obtained is pref. from 3 to 4 x 10 power 12 Boron atoms per square cm for a corresponding doping level of 2 x 10 power 14/c.c in the collector zone. Pref. heat treatment follows for 10 mins. at 1000 deg.C in an Ar atmos.