Method of manufacturing a DMOS

Claim 1

A method of manufacturing the source region of a vertical DMOS component, comprising the steps of: (a) successively depositing a first oxide layer, a nitride layer and a second oxide layer of predetermined thickness, on a substrate covered with a gate oxide layer and an intermediate polysilicon layer; (b) etching away according to a mask pattern, said first oxide layer, said nitride layer, and said second layer so as to let in place two protective studs the interval between said studs corresponding to a first zone to be doped according to a first conductivity type and the position of said studs corresponding to two windows over second zones to be doped successively of the first and second conductivity types; (c) removing said polysilicon layer inside said studs; (d) etching any portion of the oxide layer in said window; (e) doping of a first high concentration type the first zone to be doped; (f) oxidizing the structure whereby the protective studs are much less oxidized than the rest; (g) partially removing the oxide layer formed during step d) and etching away the studs and the underlying portion of said polysilicon layer, thus defined by said windows; and (h) doping successively of a first and a second type silicon zones accessible through said windows, freed by disappearance of the studs.

Claim 2

A method of manufacturing the source region of a vertical DMOS component, comprising the steps of: (a) successively depositing a first oxide layer, a nitride layer and a second oxide layer of predetermined thickness, on a substrate covered with a gate oxide layer and an intermediate polysilicon layer; (b) etching away according to a mask pattern, said first oxide layer, said nitride layer, and said second layer so as to let in place two protective studs the interval between said studs corresponding to a first zone to be doped according to a first conductivity type and the position of said studs corresponding to two windows over second zones to be doped successively of the first and second conductivity types; (c) removing said polysilicon layer inside said studs; (d) etching any portion of the oxide layer in said window; (e) doping of a first high concentration type the first zone to be doped; (f) oxidizing the structure whereby the protective studs are much less oxidized than the rest; (g) partially removing the oxide layer formed during step d) and etching away the studs and the underlying portion of said polysilicon layer, thus defined by said windows; and (h) doping successively of a first and a second type silicon zones accessible through said windows, freed by disappearance of the studs.