Formation of ultrathin SixNy layers on silicon utilizing PECVD

We exposed crystalline Si (C-Si) substrates to a NH3 plasma by the method of plasma enhanced chemical vapor deposition (PECVD) and the Si substrates were nitrided at a nitridation temperature, Tn, between 300 and 600 °C. The nitrided layers were grown directly on n-type C-Si substrates with high resistivity for measurements of electron resonance (ESR) and Fourier transform infrared (FTIR) absorption. The intensity of the N–H IR bending band increased with increasing Tn up to 450 °C, and then decreased again with a further increasing in Tn. We found a strong correlation between the change in the ESR spin density, Ns, and that in the N–H bending intensity, which was obtained from the spectral intensity at around 1200 cm−1. Furthermore, incorporation of N atoms in amorphous SixNy layers may improve the structural property at Tn = 450 °C for various insulating applications. In addition, we found that the atomic densities and/or composition of a-SixNy may decrease the BHF etch rate.