JPS6461949A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a collector buried diffusion layer of a uniform thickness and contrive to make a layer fine, by making openings of fine patterns on an oxide film which is formed on a substrate. CONSTITUTION:An oxide film 10 is formed at the surface of a semiconductor substrate 1 and the oxide film 10 of a region where the collector buried diffusion layer 21 is formed has openings so that the fine openings 22 are spread all over the oxide film 10 by using the processes of photolithography and etching. After that, a coated insulating film 11 containing P, As, Sb, and the like is applied to the full face of the oxide film 10 and the openings 22. The coated insulating film 11 acts as a impurity diffusion source for forming the N-type collector buried layer 21. Since impurity elements are diffused thermally by the coated insulating film 11, heat-treatment is performed at a temperature around 800-1100 deg.C and the above diffusion layer 21 is formed in the substrate 1. In this way, the coated insulating film 11 is embedded in the fine openings 22 almost uniformly and as a result, all the supply of the impurity elements reaches the sane level at the openings of the oxide film 10 for impurity diffusion masks and then impurities diffuse uniformly through thermal diffusion and the amount of diffusion in the transverse direction becomes small.