IMPROVEMENT IN DIELECTRIC-PROPERTIES OF LOW-TEMPERATURE PECVD SILICON DIOXIDE BY REACTION WITH HYDRAZINE

The dielectric properties of plasma-enhanced chemical vapor deposition (PECVD) SiO2 deposited at 150 degrees C were improved by reaction with anhydrous hydrazine vapor at 150-350 degrees C. The permittivity and loss decreased similar to 32% and similar to 86%, respectively, after reaction with hydrazine at 150 degrees C. The decrease in permittivity and loss correlated with a decrease in the dipole concentration (silanol + water). During exposure to humid conditions, water uptake in the SiO2 films degraded the dielectric properties. A nitrogen anneal at 350 degrees C did not improve the dielectric properties of the PECVD SiO2. Although water was removed from the films, silanol remained. When the PECVD SiO2 deposited at 150 degrees C was reacted with hydrazine vapor at 150 degrees C, both silanol and water were removed from the films. The dielectric properties and resistance to water absorption improved.