| 摘要 |
PURPOSE:To enable minute patterning requiring no over-etching, to prevent leakage and the degradation of dielectric resistance through an oxide film, to form the gate electrode of a minute pattern and to improve the degree of integration by uniformly growing the oxide film onto the surface of a poly Si layer functioning as a gate in an EPROM. CONSTITUTION:The gate oxide films 5 are each shaped through thermal oxidation in a P type silicon substrate 1, and the poly Si layer 6 of the first layer is grown on the whole surface. The poly Si layer 6 is etched by using masks 7. In this case, etching is controlled so that the poly layer 6 is left in approximately 500Angstrom thickness at a position where there is no mask, and comparatively thick poly Si layers 6a1, 6a2 and 6a3 and thin poly Si layers 6b in approximately 500Angstrom thickness are formed continuously. SiO2 Films 8 as layer insulating films are shaped to the surfaces of the thick sections 6a1-6a3 among said poly Si layers through heat treatment in a thermal oxidation atmosphere, and the thin sections 6b are oxidized completely and changed into SiO2 films 9 unified with said gate oxide films 5, and the films on field SiO2 films 2 are turned into SiO2 9 unified with the field SiO2 films. The approximately uniform SiO2 films 8 can be shaped to the surfaces of the poly Si layers 6a1-6a3 through the thermal oxidation process. |
