Annealing Effects on Silicon Oxynitride Layer Synthesized by N Plasma Immersion Ion Implantation

A silicon oxynitride layer was obtained on a polished silicon wafer surface by nitrogen plasma immersion ion implantation. Oxygen is provided by the residual gas in the implantation chamber (base pressure of 3times10^-5 mbar) and is also implanted as the main impurity. As-implanted Si samples were analyzed by high-resolution Auger electron spectroscopy (AES), which indicated the formation of a SiO_xN_y layer of about 30 nm with varying x and y, along the depth of the treatment layer. AES also provided concentration profiles of the implanted elements at the as-implanted stage. Annealing of samples from a batch of such oxynitrided Si samples was carried out at different temperatures ranging from 200 degC to 1060 degC. The AES analysis of these annealed samples indicated a significant escape of the implanted nitrogen atoms (starting already at 200 degC), but even at 1060 degC, there was a very thin (about 12 nm) remaining layer of the silicon oxynitride, which is probably in crystalline form. Results from high-resolution X-ray diffraction measurements also corroborate the aforementioned results