Dynamic Secondary Ion Mass Spectrometry is the ideal technique to use if you need an elemental depth profile of your sample with ppm to ppb detection limits up to a depth of 10 µm. D-SIMS is most commonly used to perform in-depth impurity analysis looking at dopants or low level contamination on a range of hard materials from semiconductors, metals to insulators.
How SIMS works – your sample is sputtered with a primary ion beam (oxygen or cesium), sputtering atoms from the surface. A portion of the atoms leaving the surface are ionized. These ions are extracted into a mass spectrometer and separated by their mass/charge ratio and counted. Since you are removing atoms over time with sputtering, time is related to depth. A plot of sputter time vs. ion counts can be converted to depth vs. concentration.
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Instrumentation Available
Key Attributes
- Elements detected H-U (depending on instrument configuration)
- Detection limit: ppm – ppb
- Depth profiling from few hundred nm to 10 µm
Strengths
- Depth profiling
- Parts per million to parts per billion detection limit
- Analysis of insulators and conductors
- High detection sensitivity
- nm depth resolution possible
- 3D imaging is possible
Limitations
- Destructive
- Very specific standards required for accurate quantification
- Soft material samples (polymers, biologicals) are easily damaged, limiting usefulness
- No molecular information
- Samples must be flat
- Samples need to be a minimum of 1 x 1 cm
- Samples must be vacuum compatible
Applications
- Depth profiling of metals, semiconductors and insulators
- Bulk composition measurements of hard materials
- Trace element and contamination analysis
Additional Reading
https://youtu.be/fnkXNaNekaY