Improved Properties of Silicon Nitride Films Prepared by the Catalytic Chemical Vapor Deposition Method

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Abstract
The properties of silicon nitride (SiNx) films produced by the catalytic chemical vapor deposition (cat-CVD) method are extensively studied for device application. In the cat-CVD method, the deposition gases such as a silane (SiH4)) and ammonia (NH3)) gas mixture are decomposed by catalytic cracking reactions with a heated catalyzer near the substrates, and the SiNx films are formed at substrate temperatures around 300°C without using plasma. It was found that the electrical insulating properties such as resistivity and breakdown voltage and also the optical properties of the cat-CVD SiNx films were almost similar to those of high-temperature thermal CVD films, and that the hydrogen content was much lower than that of conventional plasma enhanced CVD (PE-CVD) films and was only a few atomic percent. It was also revealed that the film was water-resistive, the chemical etching rate was just 1/10 of that for PE-CVD films, and that the step coverage of cat-CVD SiNx films was conformal. The films are expected to be used as new device passivation films and are superior to the conventional PE-CVD SiNx films.