MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To obtain finely formed LSI's with good yield by a method wherein, when the source and drain regions are formed in the surface layer part of a semiconductor substrate, the gate electrode provided between these formed regions is covered with a PSG film excellent in fluidity, which film is then made to flow down to the side surface of the electrode by heat treatment, thus controlling the areas of said regions. CONSTITUTION:A thick field oxide film 2 is formed in the periphery of the P type Si substrate 1, and a thin gate SiO2 film 3 is adhered to the substrate 1 in the surface surrounded with the film. Next, positioned on the films 2 and 3, polycrystalline Si films 40 and 41 containing an N type impurity, and PSG films 50 and 50 are formed by lamination, respectively. An ion implanted region 7 is generated in the substrate 1 on both sides of the film 40 serving as the gate electrode by the implantation of N type impurity ions with the lamination as a mask. Thereafter, the film 50 is made to run by heat treatment and thus to flow down to the side surface of the films 40 and 41 as a film 51, resulting in the control of the surface area of the region 7. At the same time, the region 7 is activated, where the N type source and drain regions 9 are diffusion-formed.