Abstract: A method of manufacturing a semiconductor device, comprising the steps of providing a semiconductor body comprising a first surface and an underlying semiconductor portion that is of first conductivity type, providing a doping material of said first conductivity type at a first portion of said first surface prior to the formation of a sunken insulating layer, said first portion being situated beside said sunken insulation layer, forming an insulation layer consisting of insulating material and sunk locally in said body from said first surface, and then introducing said doping material into said semiconductor body via said first portion of said first surface so as to form a zone of said first conductivity type, said zone contacting said underlying semiconductor portion, and zone extending at the area of contact to a depth greater than that of said sunken insulation layer.