In quantitative analysis by secondary ion mass spectrometry (SIMS) using external standards, precision and accuracy are affected by sample misalignment and different secondary ion energy distributions. To Investigate this, depth profiles of four pieces of a B-Implanted silicon wafer were obtained with samples mounted fiat, or intentionally misaligned. The B+ signal was referenced to 30Si+ and 28SI3+. In comparative analyses of four nominally Identical samples, the relative standard deviation (RSD) was 5.9% for nominally flat samples compared to 13% for misaligned samples for the 30SI+ reference ion. When 28SI3+ was used as the reference species, internal agreement was much worse (150% for misaligned samples compared to 13% for flat samples). The best results (RSD 1.9%) were obtained for analyses from the center of one large sample with 30Si+ as a reference. This study has shown that random sample misalignments lead to discrimination between analyte and reference ion species with differing energy distributions, which cause significant errors In the comparison of two samples.
ASJC Scopus subject areas
- Analytical Chemistry