Effect of ammonia plasma treatment on plasma deposited silicon nitride films/silicon interface characteristics

Abstract

The properties of silicon nitride film obtained by plasma-assisted chemical vapor deposition (plasma CVD) are studied along with the effect of NH3 plasma treatment on plasma CVD silicon nitride/silicon interface characteristics. With this NH3 plasma treatment of the silicon surface before silicon nitride film deposition, the interface state densities of the silicon nitride/silicon interface are reduced to about 1010 cm−2 eV−1 and the hysteresis voltage of the capacitance–voltage (C–V) curve is reduced to 0.1 V. These improvements are most pronounced when there is a large H concentration in the silicon nitride film. However, no effect is observed when N2 or H2 plasma was used instead of NH3 plasma. Auger electron spectroscopy analysis of the silicon surface after NH3 plasma treatment shows that nitrogen is incorporated in the near surface region of the silicon substrate. This implies that nitridation of the silicon surface occurs due to NH3 plasma treatment and the interface characteristics are improved because the silicon nitride/silicon interface is made inside the silicon substrate due to this nitridation.