Dynamic Secondary-Ion Mass Spectroscopy (SIMS) Services
Dynamic Secondary-ion mass spectrometry (SIMS) is a technique used to analyze the composition of solid surfaces and thin films by sputtering the surface of the specimen with a focused primary ion beam and collecting and analyzing ejected secondary ions.
The SIMS analysis measures the mass and intensity of secondary ions produced in a vacuum by sputtering the sample surface with energetic ion or neutral beams. The focused ion or neutral beam is directed to the sample surface, removing material at a rate determined principally by the intensity, mass, energy of the primary species and the physical and chemical characteristics of the sample. A small fraction of these sputter products is ionized, and these ions are the secondary ions in secondary ion mass spectrometry. The secondary ions are then accelerated into a mass spectrometer and separated according to their mass-to-charge ratio.
APPLICATIONS:One of the main applications of dynamic SIMS is the in-depth distribution analysis of trace elements (for example, dopants or contaminants in semiconductors). Sputter-removing material from the sample enables dynamic SIMS to determine the changes in composition or the diffusion of impurities from layer to layer. Variable primary-ion conditions allow depth resolutions of <10 nm
- Dopant profle ─ P type and N type dopant concentration control for Si, III-V matrices to optimize device performance
- Impurity profile ─ C, O, H, Al, Cr, Fe…within layers or at interfaces to maintain device performance and reliability; detection limit is controlled at 1e13 to 5e16/cm3 level
- High precision implant profile ─ dose matching of B, As, P etc
- Standard bulk elemental analysis
USES & LIMITATIONS:
- What it is great for:
- Detection of all elements from H to U
- Dopant and impurity depth profiling
- The most sensitive surface analysis technique with elemental detection limits ranging from ppm to ppb
- Requires ultra high vacuum system
- Accurate quantitation requires the use of standards
INSTRUMENTS WE USE FOR D-SIMS
Cameca IMS-4f Secondary Ion Mass Spectrometer
The Cameca magnetic sector mass spectrometer consists of an ion source, a mass-selective analyzer, and an ion detector. Our system is outfitted with:
- Duoplasmatron ion source for either positive or negative O ion generation. Additional pumping and gun isolation has been installed.
- Cs microbeam ion source with additional pumping and gun for the production of Cs+ ions.
- Normal incidence electron gun for charge neutralization while analyzing insulating specimens.