Thin films of silicon dioxide are used extensively as insulators in the fabrication of many semiconductor devices. Silicon dioxide films deposited by chemical vapor deposition typically require temperatures near 800 C. However, some processes, such as the fabrication of devices with multilevel aluminum interconnects, require deposition temperatures below 350 C. Several techniques that have been developed for low-temperature deposition of silicon dioxide include plasma-assisted deposition, low-pressure chemical vapor deposition, and photo-assisted chemical vapor deposition. Some photochemical deposition reaction use Hg vapor as a photochemical catalyst to decompose nitrous oxide in the pressure of silane. Films deposited with these reactions have been found to have adhesion problems, and tend to be in completely oxidized. Several other deposition reactions using photodissociation of molecular oxygen or disilane have been reported. (jes).