| 摘要 |
PURPOSE:To obtain a field-effect transistor having a stable LDD structure by simple processes, by utilizing the difference in size of a gate electrode after anisotropic etching and after isotropic etching as the region of low concentration drain and source diffused layer. CONSTITUTION:An isolating oxide film 2 is formed on a silicon substrate 1 having a P-type surface. Thereafter, a gate oxide film 3 is formed in a transistor forming region by a thermal oxidation method. Then, polysilicon 4 for a gate electrode is deposited by a pressure reduced CVD method. Then a gate-electrode forming pattern 5 is formed with positive resist. Thereafter, anisotropic etching of the polysilicon is performed. At this time, the size of the polysilicon after etching is about the same as the size of the resist. Then arsenic ions are implanted without removing the resist, and a high concentration drain and source diffused layer 6 is formed. The gate electrode undergoes isotropic etching. Thereafter the resist is removed by oxygen plasma. With the polysilicon electrode as a mask, arsenic ions are implanted, and a low concentration drain and source diffused layer 7 is formed. |
