| 摘要 |
After cleaning a surface of a silicon substrate ( 1 ), impurities and natural oxide film existing on the silicon substrate ( 1 ) are removed by soaking the silicon substrate ( 1 ) in a 0.5%-by-volume HF aqueous solution for 5 minutes. The silicon substrate ( 1 ) is rinsed (cleaned) with ultrapure water for five minutes. Then, the silicon substrate ( 1 ) is soaked for 30 minutes in azeotropic nitric acid heated to an azeotropic temperature of 120.7° C. In this way, an extremely thin chemical oxide film ( 5 ) is formed on the surface of the silicon substrate ( 1 ). Subsequently, a metal film ( 6 ) (aluminum-silicon alloy film) is deposited, followed by heating in a hydrogen-containing gas at 200° C. for 20 minutes. Through the heat processing in the hydrogen-containing gas, hydrogen reacts with interface states and defect states in the chemical oxide film ( 5 ), causing disappearance of the interface states and defect states. As a result, the quality of the film can be improved. Thus, it is possible to form a high quality (with low leak current density), extremely thin silicon dioxide film on the silicon substrate at a low temperature with excellent film-thickness controllability.
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