Semiconductor devices and method of manufacturing the same

Claim 1

A method of manufacturing semiconductor devices comprising: forming an insulation film which has a window for diffusion onto a semiconductor substrate, forming a polycrystal silicon film which does not contain impurities, and which covers said insulation film and the surface of said semiconductor substrate exposed through said window, forming a borosilicate glass film which contains impurities covering said polycrystal silicon film, forming a silicon dioxide film, forming a window in all said films to expose the substrate with a desired surface area, heat treating said assembly to form a source region and a drain region in said substrate and to form said insulation layer directly below the central gate electrode so that boron contained in the borosilicate glass layer diffuses into the polycrystalline layer and from the polycrystalline silicon layer, adjacent to the silicon substrate, further diffuses into the silicon substrate to form the P type source region and drain region, the diffusion, in this case, proceeding in the vertical direction only and not in transverse direction, whereby, the impurities neither diffuse to the portion directly below the window nor to the silicon dioxide insulation, a passivation film is then formed over the entire surface, a film of one of the group comprising aluminum and polycrystalline silicon is then formed over the surface, said last film is removed partially by photo etching leaving a portion behind to form a gate electrode, a window is then opened to reach said polycrystalline layer, a film of one of the groups comprising aluMinum and polycrystalline silicon is vapor deposited and selectively removed to form the source electrode and the drain electrode.