SIMS backside depth profiling of ultra shallow implants

In secondary ion mass spectrometry depth profiling, a more accurate junction depth can be acquired by sputtering from the backside of the wafer [J. Vac. Sci. Technol. B 16 (1) (1998) 298]. This technique takes advantage of the better depth resolution of the leading edge as compared to the trailing edge [Nucl. Instrum. Meth. B 47 (1990) 223]. By using silicon-on-insulator (SOI) wafers, we have developed a backside depth profiling technique for studying ultra shallow implants. The abrupt interface of the SOI wafer and the large selectivity in chemical etching result in smooth after-etched surfaces, which facilitate high resolution SIMS profiling. The true dopant distribution of B 1 keV implants was studied by performing front and backside depth profiling using SOI substrates. The 7.5 and 0.5 keV O-2(+) primary ions were used at oblique incidence in a Cameca IMS-6f, with and without oxygen flooding and sample rotation. The effectiveness of backside SIMS profiling of the ultra shallow dopant implants using SOI substrates is evaluated. (C) 2002 Elsevier Science B.V. All rights reserved.