Determination of the erosion rate in the transient region of an ultralow energy secondary ion mass spectrometry profile using medium energy ion scattering

A method which allows the erosion rate to be established from the earliest stages of an ultralow energy secondary ion mass spectrometry (ule-SIMS) profile is described. Using the technique of medium energy ion scattering (MEIS), this method provides data which enables an accurate depth scale to be established from a depth of a few nanometers onwards. The method is applicable for a thin amorphous layer at the surface or a heavy element marker in the near-surface region, and enables the erosion rate as a function of SIMS ion dose to be established for particular bombardment conditions. The erosion rate obtained is used to calibrate the depth and intensity scales of implant profile measured using ule-SIMS and to interpret the near-surface distribution. In this article we demonstrate this methodology using a Ge preamorphized Si(001) surface with a 1 keV boron implant. The altered layer formed by the primary SIMS O2+ incorporation and the redistribution of Ge in the samples used, are also described. Based on the Ge redistribution results, the possibility of adapting this method for determining erosion rates in crystalline silicon and silicon surface recession measurements, is also discussed