JPS577121A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the characteristics of an element by injecting impurity ions with an SiO2 film as a mask, then annealing the injected layer in N2 gas atmosphere containing small amount of O2, and thereby preventing the inversion of the conductive type of the substrate under the mask layer. CONSTITUTION:A thick SiO2 film 2 is formed, for example, on a P type Si substrate 1, a hole is opened at the film 2, and impurity ions of As or the like is, for example, injected on the overall surface. Thereafter, the injected layer is activated to form a desired impurity doped region 3 by a heat treatment. The atmosphere in the step of heat treating is prepared by N2 gas atmosphere containing 1-10% by volume of O2 gas, and impurity ions injected to the film 2 of the mask are converted to the substrance which is hardly thermally diffused in the film 2. Thus, it can prevent the formation of the inverted layer on the surface of the substrate 1 under the mask 2, and accordingly it can also prevent the increase in the leakage current the increase in the floating capacity as the deterioration of the characteristics.