| 摘要 |
PROBLEM TO BE SOLVED: To improve the electric and the boundary characteristics of a very thin film of specific thickness, by heattreating an Si oxide film at specific temperature higher than oxidizing temperature in nitrogen atmosphere after forming the Si oxide film at the specific temperature or less. SOLUTION: After forming an Si oxide film 2 of the thickness of 3nm or less on an Si substrate 1 at 750 deg.C or less, the Si oxide film 2 is heattreated at 850 deg.C that is higher than the oxidizing temperature in the nitrogen atmosphere and then an Al electrode 3 is vacuum-evaporated by vacuum evaporation method. The leak current of an Si oxide film that is oxidized at 650 deg.C and not heattreated is very large, the leak current of the Si oxide film that is heattreated at 850 deg.C is decreased drastically and the larger the maximum allowable voltage, the better. the gate insulating film with lower leak current. The Si oxide film that is heattreated at 850 deg.C after being oxidized at low temperature has higher allowable voltage and smaller interfacial level density. The Si oxide film is oxidized at 750 deg.C or less for the better controllability of the film thickness as the film thickness is 3nm±2% when it is oxidized at 750 deg.C, the film thickness is 3nm±4% when it is oxidized at 850 deg.C and the controllability of the film thickness is better with oxidized at lower temperature. Therefore, the Sr oxide film is oxidized at the temperature not higher that 750 deg.C for accurately controlling film thickness.
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