The isotopic comparative method (ICM) for SIMS quantification of boron in silicon up to 40 at.%

Abstract

AbstractThis work extends the Isotopic Comparative Method, which has been previously introduced with the aim of correcting matrix effects, to quantify high concentrations of boron in silicon up to 40 at.% by SIMS technique. It requires a specific sample containing two isotopes of the element to quantify: for this study silicon sample with isotope 10B present in constant, sufficiently dilute concentration, quantifiable with the conventional Relative Sensitivity Factor method and the other isotope 11B implanted at very high concentrations. The intensity of 10B, whose concentration ratio with respect to silicon is known and constant, allows to measure the matrix effects induced by the presence of 11B and to deduce the total boron concentration. The variations of the ion yields of boron YB+ and silicon YSi+ as a function of the boron concentration CB are investigated up to 40 at. %. It is found that under Ar+ sputtering there are no matrix effects on Si+ ions, but a doubling of YB+. Under O2+, YB+ and YSi+ increases almost linearly and similarly up to 2.5 times their value in dilute regime. With saturated O2 flooding under Ar+ or O2+, YB+ and YSi+ increase similarly and weakly. These results allow defining an Extended Relative Sensibility Factor method for the quantification of concentrated boron profiles in silicon. It has been successfully implemented in a ∼5 at.% boron layer obtained by Gas Immersion Laser Doping. ICM has been implemented for quantifying high dose boron implantation in silicon (CB up to 40 at.%). Copyright © 2010 John Wiley & Sons, Ltd.