New Services and Measurements from CSMA

The Kratos Axis Ultra XPS (X-Ray Photoelectron Spectroscopy) instrument at CSMA provides quantified elemental and oxidation-state information. This instrument allows CSMA to offer a number of increased service capabilities including:

• Quantified elemental depth profiling by ion beam etching as well as non-destructive angle-resolved depth profiling. This depth profiling capability allows the analysis of buried defects and interfaces. At CSMA the XPS depth profiling provides information from the outer surface to a depth of 2 μm.
  
  A commercially available DVD has been analysed by XPS depth profiling with the results shown in Figure 1 below:
  
  

  

  Figure 1: DVD Depth Profile

  
  

  5 distinct layers can be seen on the profile.

  Layer 1 0 to 11.5nm
  Protective layer containing Zn, S and O

  Layer 2 11.5 to 15.5nm
  Active layer containing 2 elements

  Layer 3 15.5 to 24nm
  A second protective layer, containing Zn, S and O

  Layer 4 24 to 50nm
  The reflective layer of Ag

  Layer 5 above 50nm
  The substrate, generally polycarbonate.

  The major benefit of this technique is that quantified information can be gained as well as layer thicknesses.

  
  
• High resolution of data.
  As can be seen in the spectra below the new instrument provides data with less peak overlaps. This increase in resolution will allow previously difficult chemical-state information, such as the oxidation-states of gold, to be resolved.
  
  

  Figure 2: XPS Spectra




• Elemental and oxidation-state imaging. Previously elemental mapping by EDX and molecular imaging by ToFSIMS has been available however now CSMA has the capability to image functional information quantitatively. The example below shows a treated medical grade fabric sample, the C-C bond of the PP substrate is coloured red whilst the C-O bond of the coating, designed to inhibit the adhesion of proteins and cells, is coloured green.
  
  

  Figure 3: XPS Chemical-state Image




• Small area analysis. Features as small as 15microns can now be analysed. Bond Pad Contamination on an electrical component was investigated utilising the new feature. An image was acquired and two areas were then retrospectively analysed with the 55micron spot size. The image below shows the areas whilst the spectra show the differences between the two areas. The contamination was identified and eliminated.




Figure 4 - Optical Image highlighting Analysis Points and Retrospective Spectra