Quantification of micro-area analysis in SIMS

Fabricating mesa structures with photolithography has been successful for depth profiling in SIMS for micrometer‐scale areas because it eliminates undesired ions originating from the surroundings of the analysis area. However, when we estimate dopant concentration from the SIMS depth profile for ion‐implanted samples using the mesa fabrication method, it is not appropriate to use a relative sensitivity factor (RSF). As an alternative to this conventional RSF method, the concentration was estimated by applying the Lindhard, Scharff, and Schiott (LSS) theory, that is, the distribution of ions penetrating into a solid are assumed to be described by a Gaussian approximation. We carried out the following process. First, the SIMS depth profile of the dopant ions with high sensitivity and high‐depth resolution for a mesa sample was measured. Second, the ΔRp value, the standard deviation of the projected range, was measured from the depth profile. Then, the peak concentration of the dopant ions was estimated from the formula using the measured ΔRp value mentioned above, assuming that implanting ions in a target material are distributed in a Gaussian distribution. This estimation method is a reasonable and practical way of obtaining dopant concentrations from a depth profile. Copyright © 2010 John Wiley & Sons, Ltd.