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

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a surface analytical technique that focuses a pulsed beam of primary ions onto a sample surface, producing secondary ions in a sputtering process. Analyzing these secondary ions provides information about the molecular, inorganic and elemental species present on the surface. For example, if there were organic contaminants, such as oils adsorbed on the surface, TOF-SIMS would reveal this information, whereas other techniques may not, particularly at very low levels. Since TOF-SIMS is a survey technique, all the elements in the periodic table, including H, can generally be detected. Moreover, this analysis can provide mass spectral information; image information in the XY dimension across a sample; and also depth profile information in the Z direction into a sample.

The surface sensitivity of TOF-SIMS makes it a good first pass at problem solving to give an overview of what types of species are present on a sample. Other techniques can then be used to obtain additional information. TOF-SIMS is also a technique that can detect species at significantly lower levels than traditional surface analysis techniques such as XPS and Auger.

EAG has been offering Time-of-Flight Secondary ion Mass Spectrometry commercially longer than any other company and our expertise is second to none. This is particularly crucial for TOF-SIMS, where the data sets can be extremely complex and may require more interpretation or data processing than other methods. The imaging capabilities of TOF-SIMS can provide elemental and molecular information from defects and particles on the micron scale. TOF-SIMS can also be used for depth profiling and complements dynamic SIMS. The advantages for profiling are its small areas capabilities and also its ability to do survey depth profiles without selecting specific elements of interest. More recently, cluster ion beams enable the profiling of organic materials whilst maintaining structurally significant information.

At EAG, we use TOF-SIMS to assist customers with quality control, failure analysis, troubleshooting, process monitoring, and research and development. For example, the information we provide when investigating wafer surface contamination issues can help determine the specific source of the problem, such as pump oils or component outgassing, or it may indicate problems with the wafer-processing step itself (e.g. etch residue). We make sure you have person-to-person service throughout the process, so that you fully understand the test results and their implications.

Ideal Uses
  • Surface analysis of organic and inorganic materials
  • Imaging of elements and molecules on surfaces
  • Failure and root cause analysis in case of delamination, blistering, de-wetting, staining, haze, etc
  • Survey depth profiling
Technical Specifications

Signal Detected: Elemental and molecular ions
Elements Detected: Full periodic table coverage, plus molecular species
Detection Limits: Fraction of a monolayer, 107 – 1010 at/cm2 (metal on semiconductor), down to 1 ppm bulk concentration in depth profiles
Depth Resolution: 1-3 monolayers (Static mode), down to 1 nm (depth profiling)
Information Depth: Below 1 nm (static mode), up to 10 μm (depth profiling)
Imaging/Mapping: Yes
Lateral Resolution/Probe Size: Down to 0.1 µm

Strengths
  • Molecular identification of compounds on a surface
  • Very high sensitivity and low detection limits
  • Imaging with ~0.2 µm resolution
  • Insulator and conductor analysis
  • Non-destructive (static mode)
  • Survey depth profiling in all sorts of materials
  • Quantitative surface coverage and concentration depth profiles for specific materials
  • On specific instruments:
    • Whole wafers up to 200 mm
    • Molecular depth profiling using an Argon gas cluster ion beams (GCIB)
Limitations
  • Usually not quantitative without standards
  • Samples must be vacuum compatible
  • No molecular information from below the outermost 1–3 monolayer(s)
  • Contamination from sample packaging and handling or from previous analyses may impact quality of results

To enable certain features and improve your experience with us, this site stores cookies on your computer. Please click Continue to provide your authorization and permanently remove this message.

To find out more, please see our privacy policy.