| 摘要 |
PURPOSE:To obtain double layer poly Si structure having high insulating properties by removing a thermal oxide film formed on the surface of a first layer poly Si film and forming a thermal oxide film on the surface of the first layer poly Si film again. CONSTITUTION:A Si oxide film 2 is grown on a semiconductor base body 1. A first layer poly Si film 3 is grown on the film 2, and phosphorus as an N type impurity is introduced. The film 3 is patterned to a desired shape to form a first layer poly Si film 3'. The film 3' is thermally oxidized in a high-temperature oxidizing atmosphere to form a Si oxide film 5. A film 4 is removed, and a final Si oxide film 5 between the first poly Si film-a second poly Si film is grown through second thermal oxidation in the high-temperature oxidizing atmosphere. Since a stepped section is reduced through the formation of the first oxide film and a removal by subsequent etching in the film 3' at that time, corner sections are rounded, and the film 5 shaped on the film 3' is formed in uniform thickness. A second layer poly Si film 6 is formed on the film 5. According to the method, the concentration of an electric field in the layer 3' section can be relaxed. |
