| 摘要 |
PURPOSE:To enable to form a second layer gate oxide film is which an outward diffusion does not arise by a method wherein, in case a gate oxide film of the second layer is formed, an oxide film is formed at low temperatures as the first step thereof and the prescribed gate oxide film thickness is obtained at high temperatures as the second step thereof. CONSTITUTION:A first layer gate oxide film 4 is formed by patterning using a first layer polycrystalline Si 5 containing high-concentration P as the mask. Then, when a second layer gate oxide film 6 is manufactured, the second layer gate oxide film 6 of 30-150Angstrom is formed, as the first step thereof, at low temperatures of 600-800 deg.C at which the outward diffusion of P does not arise. In the second gate oxidation process of the second step, 500Angstrom is formed at the usual high-temperature oxidation temperatures, 800-1,200 deg.C. A second layer polycrystalline Si 7 is formed and a gate pattern formation is performed using the second layer Si 7 as the etching mask. Since the manufacture of the oxide film 6 is performed at low temperatures at the early stage thereof, a phenomenon of outward diffusion does not arise, even though high-concentration P impurities are contained in the first layer polycrystalline Si 5 and in the back face thereof. |
