Depth profiling by secondary ion mass spectrometry

The principles and applications of depth profiling by secondary ion mass spectrometry (SIMS) are reviewed. Discussed are the basic physical processes and instrumental factors which influence the shape of depth profiles and which have to be understood or controlled for successful experimental measurements. Microroughness caused by sputtering, atomic mixing by primary beam knock‐on, and sample consumption limit the depth resolution which can be achieved while the chemical effect of ion yield enhancement by reactive species, matrix effects, and preferential sputtering can strongly affect the secondary ion signal. Instrumental effects to be controlled include beam uniformity, sample charging, and beam, and residual gas contamination. High depth resolution and sensitivity are the reasons for a wide variety of applications for SIMS depth profiling. Reviewed are measurements of the range distribution of ions implanted into semiconductors and their redistribution by subsequent annealing, studies of thin films and of oxide layers, diffusion measurements in metals, semiconductors, and minerals, measurements of elemental surface enhancements in airborne particles, and lunar glass spherules, and the search for solar wind implanted ions in lunar crystals.