SIMS Measurements of As at the SiO₂/Si Interface

Abstract

SIMS measurements of concentrations at, or near, an interface are complicated by changes in the degree of ionization of sputtered atoms, in the sputter rate and in any selective sputtering effects [1]. For practical applications, bombardment conditions must be chosen to minimize these matrix effects,and calibration procedures must be established for the interface region. Measurements of dopant concentrations near the SiO₂/Si interface have been accomplished by determining concentration factors to quantify the secondary ion yields using implant standards and using O₂ ⁺ bombardment with, and without, O₂ backfill [2,3]. Appropriate choices of conditions are not always the same; to study B segregation, Morgan et al. [2] have used O₂ ⁺ bombardment with near grazing incidence (using a Cameca instrument), whereas to study As near the interface, Frenzel et al. [3] have used O₂ ⁺ bombardment and O₂ backfill conditions at normal incidence (using an Atomika instrument). In this study, we have investigated the techniques necessary to study As segregation at the SiO₂/Si interface using a Cameca IMS 3f instrument and have used Auger Electron Spectroscopy to confirm the SIMS results.