Atomic-order nitridation of Si by radical-and ion-induced reactions using an ultraclean ECR nitrogen plasma

摘要

Atomic-order plasma nitridation of Si by a nitrogen plasma without external substrate heating was investigated using an ultraclean ECR plasma apparatus. The N atom concentration increased with the plasma exposure time and tended to saturate to a value corresponding to a few atomic-layers. When the shutter in front of the wafer was closed to suppress the direct ion incidence, the N atom concentration was smaller than that with the shutter opened, and was normalized by the product of the relative optical emission intensith and the nitrogen plasma exposure time. Then, it was found that the surface reaction with the radicals proceeded according to Langmuir-type knetics neglecting desorption. when the N atom concentration became higher than that corresponding to twice atomic-layer, the ion-induced reaction was suggested to contribute to nitridation and proceed to the deeper atoms of the surface.