Ammonia-free deposition of silicon nitride films using pulsed-plasma chemical vapor deposition under near atmospheric pressure

Abstract

Ammonia-free deposition of silicon nitride (SiNX) films have been achieved on Si(100) substrate at low temperature (200°C) by using plasma enhanced chemical vapor deposition operated at near atmospheric pressure. A pulsed power supply enables a stable discharge of a SiH4–H2–N2 system at near atmospheric pressures without using any inert gases such as He. Characterization by x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy indicates that the grown film is a SiNx film with its N∕Si ratio varying for 0.85–0.90, depending on the N2∕SiH4 flow ratio (1000–4000). Despite the use of N2 instead of NH3, a high rate growth (10–70nm∕min) is enabled, which would be beneficial in forming protection/passivation layers in solar cells. The breakdown field of 7.4MV∕cm seems also promising for its use as a gate insulator in amorphous-silicon-based thin film transistors (TFTs).