JPS5737857A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make the acute angle section of a window gentle at a temperature having no adverse effect on the diffusion of impurities, and to obtain the device having no disconnection and high reliability by using a PSG, the concentration of P thereof is high and is of a thin film. CONSTITUTION:A field oxide film 12, an oxide film 12' for preventing diffusion, poly Si gate electrodes and N<+> layers 15 are formed to P type Si 11, the PSG16, P content thereof is large and thickness thereof is approximately 4,000Angstrom , is stacked and electrode windows are shaped. When the whole is heated for ten min. at approximately 1,000 deg.C, the acute angles of the windows are removed. Poly Si 19 is stacked lightly and a thermal oxide film 20 is formed, and a Si3N4 mask 21 is executed through a plasma CVD method. The poly Si 19 is selectively changed into SiO2 22 through wet oxidation. The N<+> layers 15 are diffused and turned into N layers. Si3N4 is removed with hot phosphoric acid, a SiO2 thin-film on poly Si is removed with HF and Al wiring 23 is performed. According to this constitution, the window sides of the PSG are smoothed through temperature treatment which has an effect on a diffusion condition of impurities and does not degrade characteristics, and disconnection can be prevented.