Depth Profiling by SIMS: Depth Resolution, Dynamic Range and Sensitivity

Abstract

Secondary ion mass spectrometry (SIMS) utilizes a beam of energetic primary ions to sputter away a solid [1] surface producing ionized sputtered particles which can be mass spectrometrically detected. This technique provides in-depth information on atomic constituents by recording one or more mass peaks as the sputtering process erodes the sample, thus producing the detected signal from increasingly greater depths beneath the original sample surface. This depth profiling technique has become one of the most important uses of SIMS, but the accuracy with which the data reflect the original atomic profile within the sample depends on many parameters. Several critical reviews on depth profiling exist in the Ref. [2,3,36] which broadly cover most aspects of this mode of analysis. The present work is limited to three major aspects: 1) depth resolution, 2) dynamic range, and 3) sensitivity. The relationships between these areas will be discussed, as well as how they influence the accuracy of the final profile.