Dynamic Secondary-Ion Mass Spectroscopy (D-SIMS) Services

 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

MEASUREMENTS:

  • 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
  • Limitations:
    • Requires ultra high vacuum system
    • Accurate quantitation requires the use of standards
    • Destructive

Example D-SIMS Outputs

Depth profile of AlInGaP LED device
Cameca IMS 4F SIMS
High precision depth profiles of a boron implanted Si sample.
SIMS Cameca IMS 4F

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.