Anodic oxidation of Si in oxygen/chlorine plasma |
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Abstract: | By adding a few percent of chlorine to oxygen plasma, the anodization rate of Si was enhanced; for example, the rate was doubled for oxygen containing 3-percent chlorine. With a chlorine concentration of 1.5 percent, the density of trap states at the Si-SiO2interface was reduced from 7×1011/cm2.eV to 5×1011/cm2.eV at the midgap of Si; after annealing at 800°C in argon for 60 min, it was reduced to 8 × 1010/cm2.eV, and did not return to the original value after heating the specimen to 800°C. The density and capture cross section of traps in plasma-anodic oxide were also measured using the constant-current avalanche-injection method. The number of electron traps with small cross sections in plasmaanodic SiO2films was reduced by annealing them at 800°C in argon, but SiO2films which were anodized in oxygen/chlorine plasma showed an increase of trap density under the same annealing condition. |
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