Thermal effects in atomic-order nitridation of Si by a nitrogen plasma

Abstract

Thermal effects in atomic-order nitridation of Si(100) by an electron-cyclotron-resonance nitrogen plasma were investigated by controlling the Si surface temperature. It is found that the N atom concentration increases linearly and then tends to saturate with increasing plasma exposure time. In the radical reaction limited nitridation, the N atom concentration on the Si surface is normalized by the radical density in the nitrogen plasma, and the nitridation rate does not depend on the Si surface temperature above about −25 °C and decreases with decreasing the temperature below about −25 °C. The saturated N atom concentration is a single atomic layer and more than double atomic layers on the Si surface of about −80 °C and above about −25 °C, respectively. On the other hand, by the contribution of the incident ion, the nitridation of the deeper Si atoms below the surface is enhanced, and the saturated N atom concentration is lower at higher pressure and lower Si surface temperature. Consequently, it is sugg...