JPS5737858A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To conduct layer insulation, which has few defects and high dielectric resistance, by sufficiently utilizing the characteristic stabilizing effect of a PSG and fluidity at a high temperature. CONSTITUTION:Thermal oxide films 6 are formed to a gate electrode by poly Si on a P type Si substrate 1 and the surfaces of wiring layers 4, and the whole surface is coated with poly Si 7 and the PSG8. When wet oxidation is performed at 1,000 deg.C, the PSG8 is fluidized while the poly Si under the PSG is converted into a thermal oxide film 70. The gate electrode and the lower wiring 4 are protected with the oxide films 6 during that time, and a source and a drain 5 are not also affected because they are coated with an oxide film 3 while the poly Si 7 is all changed into the thermal oxide film 70 because the PSG8 easily passes an oxidizing agent. According to this constitution, since the film 70 obtained has few defects, dielectric strength is made large and the steep inclined planes of the lower wiring are covered gently, electrostatic focusing is not generated, and the layer insulation with no partial breakdown can be obtained.