| 摘要 |
PURPOSE:To improve the accuracy of the width of a low concentration impurity layer by a method wherein an oxide film is formed by low-temperature thermal oxidation to a low-concentration-doped semiconductor substrate and a gate electrode made of high-concentration-doped polycrystalline Si, thus making the gate electrode as a mask. CONSTITUTION:A field oxide film 22 is formed on the Si substrate 21. Next, a thermal oxide film 23 is formed on the surface of an element region on the substrate 21. Then, a high-concentration-doped polycrystalline Si film 24 is deposited. The film 24 is formed by etching into the gate electrode 25 trapezoidal in cross-section. Low concentration impurity layers 271 and 272 are formed with the electrode 25 and the oxide film 22 as a mask. Oxide films 28 and 29 are formed by low-temperature thermal oxidation. At this time, a thick oxide film 29 is formed on the electrode 25. Finally, high concentration impurity layers 301 and 302 are formed with the electrode 25 and the oxide film 22 as a mask. |
