A Comparison of Camera-Based and Quantized Detectors for Image Processing on an Ion Microscope

Secondary ion mass spectrometry (SIMS)/ion microanalysis of materials surfaces is capable of detecting all the elements in the periodic table and provides the highest elemental detection sensitivity of all existing microanalytical techniques[l]. SIMS/ion microanalysis performed on the CAMECA IMS-3f Ion Microanalyser not only provides these elemental detection capabilities but also produces mass-selected ion images of the secondary ions formed during the sputtering process. These secondary ion images are produced by combining specialized secondary ion extraction and focusing ion optics with a stigmatic focusing mass spectrometer. The ion images are observed by converting the ion intensity into visible light through the use of a microchannel plate (MCP)/fluorescent screen image intensifier. Although the ion optics of the CAMECA IMS-3f are capable of resolving the lateral distribution of secondary ion emission down to a lateral resolution of ~0.3μm, the ion images produced on the standard imaging detector contain only a qualitative measure of the secondary ion signal intensity. The incorporation of a quantitative image detector (i.e. a detector which quantitates the ion intensity in the image) would provide a means of extending the microanalysis capabilities of the IMS-3f into areas such as three-dimensional depth profiling, multi-area, multi-element analysis and quantitative and lateral distribution analysis.