Approach to the characterization of through-oxide boron implantation by secondary ion mass spectrometry

Secondary ion mass spectrometry analysis of through-oxide ion implantation in silicon often exhibits strong matrix effects across the SiO2/Si interfac e. In this study we explored the analytical conditions that required minima l correction for the variation in the relative sensitivity factors and the sputtering rates across the interface. We found that an O-2(+) beam at I ke V and 46 degrees provided an equal sputtering erosion rate for SiO2 and Si. Under these sputtering conditions, the SiO2 surface remained smooth, but S i became rough similar to 50 nm below the SiO2/Si interface. A complete dep th profile of B implantation through oxide was obtained by utilizing the 1 keV 46 degrees O-2(+) beam in SiO2 and across the SiO2/Si interface and a I keV 60 degrees O-2(+) beam deeper in the Si substrate. The data exhibited an apparent drop in the concentration of the implanted B at the SiO2/Si int erface which was attributed to a phase transition in the matrix from amorph ous to crystalline. In addition, analyses of an ion-beam synthesized oxide (5 keV O-2(+) at normal incidence) confirmed the occurrence of outdiffusion of B in the altered layer. Also, the results indicated preferential sputte ring of B at the surface. (C) 2001 American Vacuum Society.