BACK

Time-Of-Flight Secondary Ion Mass Spectroscopy

Description

ToF-SIMS refers to the analytical technique Secondary Ion Mass Spectroscopy (SIMS) based on Time-of-Flight mass spectrometer (ToF). This is the most sensitive method among all surface techniques to detect small traces of impurities. The main features of the ToF-SIMS technique include:

 
 
  • detection of all elements
  • masses up to 10,000 mass units can be routinely measured
  • separation of isotopes
  • chemical information can be obtained by identifying molecular and cluster sputtered ions
  • detection limits of 1 ppm of a monolayer
  • surface sensitivity < 1nm
  • lateral resolution better than 100 nm for elements, or 0.5 um for big molecules
  • depth resolution < 1nm
 
 

 

Operational regimes and modes odes of operation

The operational regimes include:

  • surface analysis - also known as Static SIMS - employs low primary ion densities and low ion dose to prevent surface destruction as much as possible
  • imaging - using fine focussed ion beam rastering over the surface produces mass resolved images of the surface
  • depth profiling - known as Dynamic SIMS - high primary ion dose densities are applied to remove the surface layer by layer; by acquiring spectra during the sputtering the in-depth distribution of elements and small clusters (e.g. oxides) can be monitored.

The modes of operation and the involved analysis parameters depend on the instrument used. A table for our instrument can be found if you click on the link below.

 
   

Applications

Microelectronics for detecting surface contamination (elemental, molecular), de-lamination, lubricant degradation, depth distribution of impurities; thin films technology, corrosion, painting failure (such as craters) etc.

 
 

 

Instrumentation: ION-TOF IV (IonTof GmbH)

Location: CME-124

Examples:

Depth profiling of FeCoNi thin films

Depth profiling of multiple bilayers

Imaging of Pt patterns on Au thin film

Imaging of corrosion cracks

Imaging of DNA biosensors

Imaging of LB films 1 & 2

Imaging of Mayerthorpe meteorite

Imaging of color pen inks