Acquiring an XPS Alignment
XPS alignment tips:
- If you are planning on acquiring an XPS depth profile, the X-ray source needs
to be back from the sample far enough so as not to block the ion beam’s trajectory to the sample. This results in a drastic reduction of signal, so
only alternating sputter depth profiles are practical.
- The Alignment acquisition is used for optimizing the position of the sample
with respect to the analyzer. It is also used to position the X-ray source for
maximum counts.
- For 15-255G, 25-260, 25-270 cylindrical, you may want to first perform an AES
elastic peak alignment to ensure that the sample is at the focal point of the
analyzer. For SCA systems, line up the sample to the center of the front
viewport.
- Lower the X-ray source to ½” from the sample.
- Make sure that the X-ray source is on and set to 100 watts at 10kV minimum.
The maximum power limit for the 04-151 10kV X-ray source generator is 400 watts
at 10kV. The maximum recommended power limits for the 04-500/548 X-ray source
generator is 300 watts at 15kV, per anode.
- Set the aperture(s) on the 15-255G analyzer to XPS. For 25-260 and 25-270
analyzers, set both apertures to large (center).
- Set the technique to XPS.
- Select the New Alignment command from the Acquisition menu (or click on the
appropriate toolbar button).
- Set the upper limit and lower limit binding energies to scan a range that will
display a known peak on your sample. If you do not know what elements your
sample is composed of, acquire a survey and determine the largest peak position
and enter those values.
- If you have a 20-810 analyzer control, set the pass energy to 100-pass energy.
If you have a 20-805 analyzer control, you must manually change the pass
energy on the 20-805 (the pass energy value entered in the software is for
bookkeeping purposes only). For the 10-360 analyzer, set the pass energy to
approximately 100. For that analyzer, only specific pass energies and eV per step
combinations are possible. This ensures that the proper energy distribution across
the detector is maintained.
- Acquire the alignment and a peak(s) will be displayed. The maximum peak
position and counts are updated each sweep. If you have a 32-100 or 80-365 electron
multiplier supply, the computer automatically sets the correct multiplier
voltage. If you have a 20-075 electron multiplier supply, you must manually set
the voltage to the correct value. If you are uncertain of this value, simply
increase the multiplier voltage until no further increase in counts is noted.
This value is typically 1800 to 2200 volts.
- Being careful not to touch the sample with the X-ray source. Adjust the X-ray
source position (X, Y, and Z) for maximum signal height.
The sample is now aligned. You can now acquire other XPS data, such as
surveys, multiplexes and depth profiles.
You can now acquire XPS data.
XPS Acqusition Procedures