Ultrathin oxynitridation process through ion implantation in a poly Si 1− xGe x gate MOS capacitor

Abstract

Effect of temperature and time of heat treatment on the distribution of ion-implanted nitrogen in poly Si 0.65Ge 0.35 gate MOS samples was studied. Secondary ion mass spectrometry (SIMS) was used for the qualitative analysis of the nitrogen distribution. Rapid thermal processing was carried out for a temperature range of 950–1070°C for the redistribution of ions. The nitrogen implantation doses were 5×10 14 cm −2, 2×10 15 cm −2 and 5×10 15 cm −2, all with an implantation energy of 50 keV. For a uniform distribution of nitrogen in the SiO 2 region, an optimal temperature at a well calibrated time must be applied and this depends on the implantation dose. For medium and high concentrations the optimal conditions were 1050°C and 15 s, and 1070°C and 15 s, respectively. A uniform nitrogen distribution could be obtained throughout the SiO 2 film. Prolonged heat treatment can cause degradation of the oxide layer and movement of the nitrogen and oxygen into the channel and the poly-Si 0.65Ge 0.35 layer.