SIMS analyses of ultra-low-energy B ion implants in Si:: Evaluation of profile shape and dose accuracy

Numerous experimental studies for near-surface analyses of B in Si have shown that the B distribution within the top few nanometers is distorted by secondary ion mass spectrometry (SIMS) depth profiling with O-2-flooding or normal incidence O-2 bombardment. Furthermore, the presence of surface oxide affects the X-j determination as well as B profile shape when SIMS analyses are conducted while fully oxidizing the analytical area. Nuclear techniques such as elastic recoil detection (ERD), nuclear reaction analysis (NRA), and high-resolution Rutherford backscattering spectrometry (HR-RBS), are known to provide a profile shape near the surface that is free of artifacts. Comparisons with SIMS analyses have shown that SIMS analyses without fully oxidizing the analytical area agree well with these techniques at sufficiently high concentrations (where the nuclear techniques are applicable). The ability to measure both the B profile and an oxide marker with this non-oxidizing SIMS technique also allows accurate positioning of the B profile with respect to the SiO2/Si interface. This SIMS analysis protocol has been used to study the differences in near-surface dopant distribution for plasma-based implants. This study specifically focuses on measuring near-surface profile shapes as well as total implant doses for ultra-shallow B implants in Si especially those made with high peak B concentrations. (c) 2007 Elsevier B.V. All rights reserved.