Chemical vapor deposition synthesis and characterization of co-deposited silicon–nitrogen–boron materials

Abstract

Si–N–B films have been deposited by LPCVD from SiH4/B2H6/NH3 gas mixtures. The influence of the temperature and the composition of the gas mixture on the deposition process and film properties has been investigated. At 1000 °C, for the highest ammonia flow rate (SiH4 :B2H6 : NH3, 10 : 25 : 500), a mixture of turbostratic boron nitride and silicon nitride was deposited. For decreasing ammonia flow rates the Si–N–B ternary system was formed (1260 cm−1 band in the infrared spectra), which co-exists with the unstable turbostratic boron nitride structure. Finally, for a low NH3 flow rate of 100 sccm, stable amorphous films are obtained. On the other hand, at 800 °C, stable films with a high content in the ternary Si–N–B compound were obtained for a wide range of ammonia concentrations (100–500 sccm). At this temperature (800 °C), the composition of the films, as measured by Auger and photoelectron spectroscopies, strongly depends on the [SiH4]/[B2H6] ratio in the gas mixture. The improvement in the mechanical and chemical properties of the samples has been associated with the increase in the content of Si–N bonds in the Si–N–B films.