I am trying to measure bond level information as a function of depth (argon ion milling) on fused silica (SiO2) sample with features on the sample at micron size. I have previously had good success with measuring chemically similar samples with features that such that the analyzed site is nominally smooth. The high surface area of the micron-size features is causing a significant amount of charging to the extent that I cannot consistently get useful data.
Some important info:
-Neutralizer is already maxed out
-I am etching about as slow as I possibly can, with rest intervals after etching about 5 minutes before analyzing.
-Pass energy is currently at 160
-Changing the angle is unlikely to effect results based on feature type
-I can't disclose all elements I'm analyzing, but suffice to say Si and O peaks are present
-Peaks are shifting greater than 10 eV up in Binding Energy, even larger sometimes later in the run. Normal peak shift for 5 mm sample after many etching cycles is no greater than 1-2 eV.
Any fundamental strategies that I'm missing or relevant papers would be greatly appreciated. From the few papers that I've seen doing similar studies, it seems possible but the relevant methods are always scarce on details.
Fused silica charges significantly, I have had success doing measurement by using both a nickel mesh on top and having electron flood gun on for a typical measurement and it works every time.
Thanks for responding Tahereh! I like this idea. We already try to mitigate charging using copper tape near the analysis site, but I may try something like this in the future. What is the approximate wire/pore size of the mesh that you would use? Anything with pores smaller than about 1 mm would be too small for Argon milling I imagine?
Yes, the nickel mesh is fine (the one I used is smalker than 1 mm) and I can ser that can be problematic with milling. You may want to use your copper tape or even carbon tape, to connect the top of the sample to the conductive substrate, that can halp too this is used in SEM microscopy. Hopefully this in addition to the flood gun can be enough for charge compensation of your sample.
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