Dynamics of the ion beam induced nitridation of silicon

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 theta(c1) and theta(c2), corresponding to the formation of stoichiometric and overstoichiometric Si-nitride layers, respectively. For the N-2(+) bombardment in the 10 to 13.5 keV range, theta(c1) changes from 40degrees to 45degrees, while theta(c2) changes from 28degrees to 30degrees. Further, strong oscillations in the secondary ion signal, observed for angles of incidence below theta(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. (C) 2002 American Vacuum Society.