Low Dielectric Constant Films Prepared by PECVD from Tetramethylsilane

Dielectric films have been prepared by RF plasma enhanced chemical vapor deposition from mixtures of tetramethylsilane with oxygen. The films have been characterized as-deposited and after annealing at 400° C to determine the thermal stability of their properties. RBS and FRES have been used for determination of the composition of the films. Optical properties were chatacterized by FTIR and measurements of the index of refraction and optical gap. The electrical properties were measured in a SIM configuration.
It has been found that the index of refraction decreases and optical gap and dielectric constant increases with increasing oxygen concentration in the gas feed. While the material did no show a mass or composition loss after annealing, the annealing resulted in a reduction of the dielectric constant of the films. Dielectric constants as low as 3.1 have been obtained after annealing the film deposited from pure tetramethylsilane