Low-Temperature Thermal-Oxidation of Silicon

A native silicon-oxide layer has been thermally grown at 250°C by using a nitric and sulfuric acid mixture in a liquid phase under high-pressure conditions. It was found that the grown oxide layer was mainly of silicon-dioxide; however, the density of intermediate oxide was higher than that in a conventional and a thermally-grown oxide layer. The resistivity and the breakdown field strength of the oxide layer were more than 10¹⁴ Ώm and 4 MV/cm, respectively. The interface state density, evaluated from high-frequency C-V characteristics, showed a V-shaped distribution and its minimum value was about 10¹¹/cm²eV.