Near-surface secondary-ion-mass-spectrometry analyses of plasma-based B ion implants in Si

Abstract

Numerous experimental studies for near-surface analyses of B in Si have shown that the B distribution within the top few nanometers is inaccurately characterized by secondary-ion-mass-spectrometry (SIMS) depth profiling with O2 flooding or normal-incidence O2 bombardment. Furthermore, the presence of surface oxide adversely affects the Xj determination as well as the B profile shape when SIMS analyses are conducted while fully oxidizing the analytical area. Many comparisons of SIMS analyses with techniques such as elastic recoil detection, nuclear reaction analysis, and high-resolution Rutherford backscattering spectrometry, which are known to provide an accurate profile shape near the surface, have shown that SIMS analyses without fully oxidizing the analytical area agree well with these high-accuracy techniques at sufficiently high concentrations. The ability to measure both the B profile and an oxide marker with this 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 (plasma doping). This study specifically focuses on the ion energy distribution behavior of BF3 and B2H6 implants, where the effects of the implant species chemistry were of interest, as well as studying the differences of the applied electric field.