Dose calibration for through-oxide doping distributions from time-dependent secondary-ion-mass-spectrometry depth profiles with only one sensitivity factor

Abstract

A simple method is described for calibrating the dose of impurity depth profiles in Si, SiO2, and SiO2 on Si by secondary ion mass spectrometry (SIMS). Use is made of the fact that, with normally incident O2+ beams, the ionization probabilities of impurity and matrix secondary ions as well as the partial Si sputtering yields are the same for Si and SiO2. This allows dose calibration against a reference sample to be achieved for any sequence of layers of the two materials and without depth calibration. SIMS profiles of 5 keV 11B equal-dose implants in Si, SiO2, and a thin layer of SiO2 on Si show that the concept is valid to ±1% or better. Differences in the reflection coefficient of 11B from the different targets could be identified clearly.