Time-of-Flight SIMS (ToF-SIMS)

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS)

ToF-SIMS is a surface analytical technique that uses an ion beam (primary ions) to remove small numbers of atoms and molecules from the outermost layer of a surface and analyzes those that are ionized (secondary ions). A short pulse of primary ions strikes the surface and the secondary ions produced in the sputtering process are extracted from the sample surface into a time-of-flight mass spectrometer. These secondary ions are dispersed in time according to their velocities (which are proportional to their mass/charge ratio m/z). Discrete packets of ions of differing mass are detected as a function of time at the detector.

ToF-SIMS is capable of detecting ions over a large mass range of 1 – 10,000 atomic mass units at a mass resolution of 10,000. The technique is capable of generating an image of lateral distributions of these secondary ions at spatial resolutions of better than 0.15 microns. Pulsed operation of the primary beam allows insulating surfaces to be completely neutralized between pulses using a low energy electron beam.

A) Negative ion spectra showing that different silicones have different fingerprints, B) ion images of a sectioned rat brain and C) depth profiles of a multilayer specimen.

Instrument:

ION-TOF-SIMS IV equipped

  • Bi+, Bi3+, Bi3++, Cs+ and C60+ ion sources

System Capabilities:

  • Bismuth primary ion source (Bi+, Bi3+, Bi3++) for enhanced yields of organics and greater elemental sensitivity (the first in Canada)
  • Other primary ions available: Cs+, C60+
  • Dual beam sputtering (for depth profiling) using Cs+ and C60+. Profile depths from a few nanometers to several microns
  • Charge compensation using a pulsed electron-gun and/or O2 flood gas allows surface analysis and depth profiling of highly insulating samples
  • The capability to investigate a 10,000 amu mass range with high sensitivity (ppm-ppb) and parallel detection of all secondary ions collected by the mass spectrometer
  • Large sample stage capable of holding wafers up to 8″ in diameter/width and 0.5″ in thickness
  • Motorized sample stage that allows for automated analysis of preselected areas
  • Heating/cooling stage

Selected Applications in Industry:

Click here for more information on applications of ToF-SIMS.

  • Identifying causes of crater defects on painted automotive surfaces
  • Analysis of microelectronic and optical devices: characterization via 3-D cross-section reconstruction from depth profiles
  • Identifying contaminants in photolithography/photomask production
  • Depth profiling of multilayers of metals and oxides
  • Imaging of biological structures
  • Surface contamination identification
  • Adhesion failure investigations
  • Surface chemistry of minerals/mineral flotation separation applications