An ultra low-temperature (< 300°C) silicon oxidation process in which KrF excimer laser light (λ=248 nm) is irradiated in highly concentrated ozone has been developed. The growth rate of SiO2 film was 5.2 nm/10 min at 300°C and 3.6 nm/10 min at 70°C. The leakage current densities of grown at 70°C SiO2 in an electric field of over 8 MV/cm match well the calculated curve based on the Fowler–Nordheim tunneling. The oxidation mechanisms for two growth modes are discussed.

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A system is described which can continuously generate/supply highly concentrated (HC) ozone gas to satisfy the future need for practical low-temperature oxidation. This system comprises four ozone vessels, each with independent temperature control. The system can supply a constant flow of HC ozone gas by allocating one of four modes of operation, i.e., accumulation/storage, vaporization (supply), evacuation, and cooling, to each of the ozone vessels so that all the modes can be simultaneously addressed. The maximum flow rate is 60 sccm with a flux stability of ±1.1%, and an ozone concentration of over 99.5 vol % can be achieved at the system outlet. The system was applied to the formation of an ultrathin SiO2 film on a 4 in. diameter silicon wafer substrate.

The quality of ozone vapor produced with a new ozone generator was evaluated. The ozone vapor was produced by evaporation of liquid ozone after accumulating it in a ozone vessel at various temperatures between 75 and 95 K. Mass analysis of the ozone vapor revealed that the purity of ozone in the vapor depended on both the ozone vessel temperature during liquefaction and that during evaporation. The purity was ∼70% when liquid ozone accumulation temperatures higher than 90 K were used. The activity of the ozone vapor was investigated by oxidation of a Cu foil under low pressure condition. The formation of a CuO layer by exposure to the ozone vapor (pressure: ∼5×10−4 Pa) at 300 °C was confirmed through x-ray photoelectron spectroscopy analysis.

Damageless conditions in AES measurement were examined carefully on both thermally oxidized and photochemical vapour deposited amorphous SiO, films as a function of dose rate and total dose. The lower dose rate resulted in the formation of a higher density of oxygendeficient defects under the constant total dose condition. Among the films examined, it was found that Fdoped films prepared by photochemical vapour deposition best resisted electron damage. The results are discussed using the model of defect generation consisting of a cascade process, bond breaking and diffusion of oxygen.