Low dielectric constant materials are cured in a process chamber during semiconductor processing. The low dielectric constant materials are cured by irradiation with UV light. The atmosphere in the process chamber has an O.sub.2 concentration of about 25-10,000 ppm during the irradiation. The O.sub.2 limits the formation of --Si--H and --Si--OH groups in the low dielectric constant material, thereby reducing the occurrence of moisture absorption and oxidation in the low dielectric constant material.