Rapid and uniform SiO₂ film growth on 4 inch si wafer using 100%-O₃ gas

We have developed a lamp-heated cold-wall chamber that can process a large Si wafer using a highly concentrated (>90 vol.%) ozone gas to achieve rapid and uniform oxidation at a lower temperature than that used in conventional thermal oxidation. Uniform SiO₂ formation with a film thickness uniformity of within 0.2 nm was achieved. The SiO₂ growth rate, however, was not markedly accelerated compared with that achieved using conventional low (i.e., 10 vol.%)-concentration O₃ gas. This was considered to originate from the decomposition of O₃ gas in the gas phase before arriving at a heated surface as determined from the local ozone concentration measurements we performed. By increasing gas flow velocity so as to reduce the area of the thermal boundary layer on the heated surface in which decomposition of O₃ to molecular oxygen is enhanced, SiO₂ growth rate was actually improved.