Reaction analysis of initial oxidation of silicon by UV-light-excited ozone and the application to rapid and uniform SiO_2 film growth

摘要

UV-light-excited O_3 prepared by irradiation of nearly 100% pure O_3 with a KrF excimer laser (λ = 248 nm, irradiated area = 30 x 10 mm~2) was utilized for low-temperature Si oxidation. The initial oxidation rate was determined, and the activation energy was shown to be almost zero (0.049 eV). To clarify the optimum oxidation conditions, the dependence of the SiO_2 film growth rate on the total photon number and the photon density was investigated. The evolution of O_3 density after UV-light irradiation was experimentally measured, and the O(~1D) density change is discussed. O(~1D) density changes are successfully explained by using a second-order reaction model, indicating that a pulse supply of oxygen atoms is essential in the initial oxidation process. The uniform oxidation of 8 in. Si wafer has been carried out using a wafer-transfer type chamber by irradiating the wafer with KrF excimer laser light expanded linearly to the wafer width by a concave lens.