Ultrashallow depth profiling of B deltas in Si using a CAMECA IMS 6f

Abstract

Secondary ion mass spectrometry (SIMS) depth profiling is an important technique for the characterization of ultra shallow junctions, thin gate oxides and other interfacial layers in modern wafer fabrication. In this study, a CAMECA IMS 6f SIMS instrument is used to study the various factors that may affect the depth resolution in ultra shallow depth profiling of a B delta doped Si standard sample. Several analyses using 0.5-2.0 keV O<SUB>2</SUB><SUP>+</SUP> have been performed with and without oxygen flooding and sample rotation. The roughening of the sputtered crater bottom is one factor that degrades the depth resolution in low energy depth profiling, and both oxygen flooding and sample rotation are shown to suppress surface roughening. In addition, the depth resolution is found to be sensitive to other factors such as ion beam mixing and as a result, impact energies as low as 0.5 keV may be needed to achieve optimum depth resolution.