Dynamics of the ion beam induced nitridation of silicon

Abstract

High-resolution Rutherford backscattering and channeling has been used to study the energy and angular dependence of the ion beam induced nitridation of Si in a secondary ion mass spectrometry system. The nitridation of Si is characterized by two critical angles c1 and c2 , corresponding to the formation of stoichiometric and overstoichiometric Si-nitride layers, respectively. For the N 2 ϩ bombardment in the 10 to 13.5 keV range, c1 changes from 40°to 45°, while c2 changes from 28°t o 30°. Further, strong oscillations in the secondary ion signal, observed for angles of incidence below c2 , are directly related to charging of the Si-nitride surface. We demonstrate that the response of the Si-nitride layer under ion bombardment during the transient stage of nitridation can be described by a second order differential equation.