| 摘要 |
PURPOSE:To attain with good reproducibility a performance of an MOS transistor with a high withstand voltage (mutual conductance, drain withstand voltage) which uses polycrystalline silicon and is fabricated by self-alignment method within a demension in a photo mask. CONSTITUTION:On an Si-substrate 21, a gate oxide film 22, a polycrystallin Si film 23 and an Si3N4 film 24 are formed sequentially, the film 24 is selectively removed by photoetching technique, and subsequently by treatment such as oxidation through heating or the like, polycrystalline film region 27, 28 inside openings 25, 26 are converted into oxide films, and after 24a-24c are removed by etching, a region which is to be a gate electrode is covered with a photo resist film 29. And after polycrystalline films 23a and 23c are removed, the oxide film is treated by etching during the time by which the gate oxide film 22 can be removed, thicker oxide films 30, 31 than 22 are left, an impurity of reverse conduction type is ion-implanted from the surface, heat-treatment is performed, and a drain region consisting of a shallow region 32 and a deep region 33 and a source region consisting of 34, 35 are obtained. |
