| 摘要 |
PURPOSE:To obtain a preferable double diffused structure by forming a gate electrode of a MOS transistor, then forming a film which contains an impurity of high diffusion coefficient on a drain forming region, heat treating it to diffuse the impurity, then implanting the impurity ions of low diffused coefficient into the surface, and then activating it, thereby eliminating a shadowing of the implanting angle. CONSTITUTION:A thick field insulating film 2 is formed on the periphery of a P type Si substrate 1, a polycrystalline Si gate electrode 4 is formed through a thin gate insulating film 3 at the center on the surface of the substrate 1 surrounded by the film 2, and the entire surface is coated by an SiO2 film 6 which contains P. Then, a heat treatment is executed to diffuse P in the film 6, N<-> type source and drain regions 7 are formed at both sides of the electrode 4, the film 6 is removed, a thin SiO2 film 8 is coated between the films 2, As ions are implanted obliquely at approx. 7 deg. through the film 8 to form an ion implanted layer 9 into the surface layer of the region 7. Then, a heat treatment is executed to activate the layer 9 to obtain a double diffused structure having the activated layer 10 on the surface. |
