We have oxidized Si wafer at lower than 200°C using an electronically excited oxygen atom that is generated by the irradiation of UV light to low pressure highly concentrated ozone gas. We used high-pressure mercury lamp, as the light source because it has a strong emission between 210 nm and 300 nm by which ozone is effectively absorbed and photo-excited. SiO2 film formation with its thickness fluctuation of less than 0.2 nm within light-irradiated area has been easily achieved as long as the intensity of the light irradiated to low-pressure ozone is uniform within 10 percent. The SiO2 film thickness is 3.3-4.1 nm at 200°C for 10 min on the 8*Si(100) wafer. By the sample rotation during oxidation process, we could oxidize the SiO2 film homogeneously on the 8" wafer. This film can be applied to a buffer layer between deposited film and poly-Si substrate of the gate dielectric film of the low temperature poly-Si thin film transistor.
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