| 摘要 |
PURPOSE:To form an LDD structure readily, by forming a gate electrode having an approximately trapezoidal cross section on a substrate, and implanting impurity ions with suitable energy. CONSTITUTION:A silicon oxide film 2, a polysilicon layer 3 and resist 4 are formed on a silicon substrate 1. A gate electrode 3b, which has an approximately trapezoidal cross section, is formed by isotropic etching. A gate oxide film 2a is formed by anisotropic etching. The resist 4 is removed, and ions of impurities are implanted with suitable energy by an ion implanting method. The suitable energy is referred to the energy, at which a certain amount of the impurity ions are implanted in the thin region of the electrode 3b down to the substrate 1 and the impurity ions do not penetrate the thick part of the electrode 3b. Thus a low concentration region 5 and a high concentration region 6 are formed in the surface of the silicon substrate, and an LDD structure is formed.
|
