JPS57162467A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make impurities of heavy metal to be absorbed in a gate oxide film, and to make the heavy metal removal process of a semiconductor device to be unnecessitated when the source and drain regions are to be formed in a semiconductor substrate by a method wherein an oxide film containing impurities is used as the diffusion source, and impurities thereof are made to be contained in the atmosphere when diffusion is to be performed. CONSTITUTION:An Si3N4 film 2 is provided on the element formation intended region 1a in the semiconductor substrate 1, thermal oxidation is performed using the film thereof as the mask, and a thick field oxide film 3 is made to be generated on the surface of the substrate 1 at the circumference thereof. Then a thin oxide film 4a to constitute a gate oxide film 4 is adhered on the film 3, and moreover a polycrystalline Si layer 5a to constitute a gate electrode 5 is pilled up being laminated thereon. After then, etching is performed to obtain the gate oxide film 4 and the gate electrode 5, and the oxide film 6 implanted with P ions to constitute the diffusion source is formed on the whole surface containing them. Then heat treatment is performed to make impurities in the film 6 to be diffused, and the N type source and drain regions 7, 8 are formed on both the sides of the oxide film 4, and at this time, the atmosphere is formed with POCl3, and the temperature is selected at about 1,000 deg.C.