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 Secondary Ion Mass Spectrometry SIMS PRINCIPLE 
Schematic profiling mode : Signal for element i, j, k, etc are monitored. This plot is then converted into concentration of element i, j, k, etc versus depth. Ionic imaging is also possible. The instrument combines ionic sputtering and magnetic mass spectrometry : a primary energetic ion beam sputters the sample surface. Secondary ions are generated in this sputtering process and are extracted from the sample. They are then analysed by a double-focusing mass spectrometer. This instrument allows three functions : It is unrivaled for its detection limits / depth resolution / concentration range :
SIMS has become a necessary technique for any activity involving semiconductors (among others). Dynamic SIMS, with a magnetic sector, is a unique instrument that combines almost all possible requirements. Sensitivity Traces are what matter in semiconductors. Traces, as well as major elements, can be measured simultaneously with this instrument. A 6-decades dynamic range is routinely available for the monitoring of trace elements. This means that concentrations as low as 1E-13cm-3 can be measured. Examples : P in Silicon, Be & Si in InGaAsP/InP structures Depth resolution Quantum wells in the nm range can be separated. Extremely high depth resolution required by ultra shallow junctions in silicon is routinely obtained, as well as depth resolution in the 10-20 nm range down to several microns. Example : Ge/Si superlattice Mass resolution Often, elements or molecules have similar masses and interfere in analysis. High mass resolution clarifies these situations. Extreme high mass resolution is obtained with our set-up. Example : P in Silicon |
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