side and under the gate region sidewall spacers are then formed along side the gate region and highly doped regions of the second conductivity type are then implanted and diffused the sidewall spacers are then removed source regions are formed over the highly doped body regions by implantation and diffusion this may be done after the sidewall spacers have been removed or alternatively by implantation before the sidewall spacers are formed in the latter alternative the subsequent diffusion is performed simultaneously with that of the highly doped body region finally standard processing steps are performed including deposition of insulating oxide over the polycrystalline silicon gate region definition of contact areas and deposition of metal on the front and rear of the substrate and a passivating glass layer on the top of the front metal the resulting structure consists of a transistor having a highly doped silicon substrate with an epitaxial layer on top lightly doped body regions highly doped body regions and source regions are formed in the epitaxial layer adjacent to a polycrystalline silicon gate structure the highly doped body regions are contained inside the lightly doped body regions and are self aligned with a gate region among others the following advantages are obtained by using the process just described a the alignment of the highly doped body regions with the gate.