Karl-Heinz Merkel

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 studied, with emphasis on the correlation of deposition parameters and moisture permeation rate. The moisture resistance of films have been characterized using 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 these films. The best moisture-resistant property in terms of WVP and stability of the film is found in the film deposited in a low frequency (LF) process with lower ratio of silane to ammonia although the general trend is toward decreased WVP with a higher ratio of silane to ammonia in the films deposited freshly by both high and low frequency processes. Too high a ratio of silane to ammonia in LF processes leads to instability of the film after long exposure in a high humidity environment.

a-SiCx :H films deposited by plasma-enhanced chemical vapor deposition at low temperature used for moisture and corrosion resistant applications

Abstract Amorphous hydrogenated silicon carbide (a-SiC x :H) films were fabricated via plasma-enhanced chemical vapor deposition (PECVD) at a low substrate temperature. The properties of the film and their correlation with the deposition parameters were investigated with emphasis on moisture and corrosion resistance. The films can be deposited with good uniformity and repeatability. The moisture resistance is mostly influenced by the reactant gas flow ratio; increasing the silane flow enhances the moisture barrier ability of the film. The deposited film is chemically inert, is not oxidized by moisture at 85°C, and remained unattacked after 2 months immersion in water at room temperature. The film is pinhole-free, and has excellent corrosion resistant properties. Thus this material is deemed a good candidate film for moisture and corrosion resistant applications.