Optimization of primary beam conditions for secondary ion mass spectrometry depth profiling of shallow junctions in silicon using a Cameca IMS-3f

Abstract

Recent advances in semiconductor technology have allowed the fabrication of Si-based devices with submicron lateral dimensions, thus requiring the concurrent development of the analytical techniques for characterization of the shallow junctions (30–100 nm) associated with such devices. Although secondary ion mass spectrometry (SIMS) provides high dynamic range and good depth resolution, accurate depth profiling of very shallow junctions require that measures be taken to minimize the broadening effects of cascade and recoil mixing caused by the primary ion beam. In this study, low-energy B and As implants into Si were analyzed using a Cameca IMS-3f. Primary ion beam parameters, including species (O+2,Cs+ and Xe+), angles of impact, energies (1.1–15.4 keV effective), and the effect of oxygen flooding, as well as secondary ion useful yields, were investigated to determine the optimal instrumental conditions for analysis of these shallow junctions. The resulting depth profiles were evaluated in terms of both dynamic range and decay length.