Moisture-resistant properties of SiNx films prepared by PECVD

The barrier properties of silicon nitride films prepared by plasma-enhanced chemical vapor deposition (PECVD) against moisture penetration were studie d, with emphasis on the correlation of deposition parameters and moisture p ermeation rate. The moisture resistance of films have been characterized us ing infrared spectroscopy and determination of water vapor permeation (WVP) rate. Our results indicate that the gas flux ratio and discharge frequency are the most important factors in controlling the moisture resistance of t hese films. The best moisture-resistant property in terms of WVP and stabil ity of the film is found in the film deposited in a low frequency (LF) proc ess with lower ratio of silane to ammonia although the general trend is tow ard decreased WVP with a higher ratio of silane to ammonia in the films dep osited freshly by both high and low frequency processes. Too high a ratio o f silane to ammonia in LF processes leads to instability of the film after long exposure in a high humidity environment. (C) 1998 Elsevier Science S.A . All rights reserved.