Abstract: Semiconductor power device including a semiconductor layer of a first type of conductivity, wherein a body region of a second type of conductivity including source regions of the first type of conductivity is formed, a gate oxide layer superimposed to the semiconductor layer with an opening over the body region, polysilicon regions superimposed to the gate oxide layer, and regions of a first insulating material superimposed to the polysilicon regions. The device includes regions of a second insulating material situated on a side of both the polysilicon regions and the regions of a first insulating material and over zones of the gate oxide layer situated near the opening on the body region, oxide regions interposed between the polysilicon regions and the regions of a second insulating material, oxide spacers superimposed to the regions of a second insulating material.