Oxidation of silicon nitride prepared by plasma-enhanced chemical vapor deposition at low temperature

Abstract

Hydrogenated amorphous silicon nitride (a-SiNx:H) films have been fabricated by plasma-enhanced chemical vapor deposition at temperatures ranging from 50 to 250 °C. It is found that as soon as the samples are taken out from the reaction chamber and exposed to the atmosphere, the a-SiNx:H films start to oxide. The oxidation processes are monitored using infrared absorption spectroscopy. A model of porous ‘‘fractal-like network’’ structure, which is probably inherent in low-temperature deposition, is proposed to explain why moisture (H2O) in the air can percolate through numerous microvoids into these films. The H2O molecules which percolate into these porous films are active to react with the —Si—N—Si—, —Si—N—H, and —N—Si—-H bonds and to form more chemically stabilized —Si—O—Si—, —Si—O—H, and H—O—H bond configurations with the result of eventual oxidization of the entire nitride films.

Plasma‐enhanced chemical vapor deposited silicon carbide as an implantable dielectric coating

“…For a-SiN deposited at low substrate temperatures (Ϸ100°C), Liao et al observed rapid oxidation to hydrated SiO 2 in humid air at a rate of 800 nm/day, while films deposited at 225°C oxidized at Ϸ1.3 nm/day. 26 IR spectral data indicated that the SiONOSi and -SiONH bonds were oxidized to SiOOOSi and SiOOH. Amorphous SiC films produced by PECVD at low temperatures (200 -400°C), however, are stable and tolerate wet processing in aggressive acidic and alkaline etchants.…”

Influence of the high-temperature “firing” step on high-rate plasma deposited silicon nitride films used as bulk passivating antireflection coatings on silicon solar cells

“…Postdeposition oxidation has been also reported for rf PECVD a-SiN x :H films deposited at low temperature. 33 It should be mentioned that the given concentrations are taken from the bulk region of the ERD depth profiles. The ETP NH 3 films as shown in Fig.…”

The role of dangling bonds in the electronic and vibrational properties of hydrogenated amorphous silicon nitrides (a‐Si – xNx : H)

“…1 -8 A large amount of basic and applicative studies have been performed using different spectroscopic techniques. In particular, Lin and Lee 9 and Liao et al 10,11 used infrared spectroscopy to follow the oxidative kinetics over long time scales. They demonstrated that samples produced by lowtemperature PECVD are porous in the bulk structure and, in particular, at the surface level.…”