We are preparing a sandwich structures of our coating (Cr2ALC) and we could not measure a thickness of the samples after dimpling. Is it possible to measure it and how?
Thanks in advance for your replies.
I also did not get your question completely...
Are you asking about measuring ex-situ - while dimpling, or measuring the final thickness in the TEM?
For the case of dimple thickness control while processing:
if on silicon - there is a color table relating the color of Si to it's thickness, works nicelly below 10um thickness;
if not on Si - you have to find a transparent piece in the middle of the dimple, a thick glue line will make a deal, and look on it under high resolution light microscope with the highest possible NA - these guys have very small focus depth, so it is possible to focus on the front and back faces of the sample separately. Then the difference gives you the value you need.
If you are interested in measuring the final thickness in TEM, than either EELS will work as suggested by Volker (you need to know the composition exactly) or a more simple trick - you focus the beam to the smalles possible spot and deposit the contamination (this happens from both sides). Then tilting the sample to a known angle and measuring the distance between front and back spots should give you the thickness, provided that you can do a simple math :)
Dear A. Obrosov,
First of all you have take care after dimpled the thickness measurement by any tools is very default because the transparent area which you have to look for is very very thin may it broken but if you want know the thickness of the dimpled area you can measured your sample before putting on the dimpling machine. And after the initial specimen thickness has been measured, the specimen is mounted and you can simply selects a dimple depth and once dimpling has begun.The precise Z position of the tool/surface interface is continuously displayed while dimpling with any tool. You cane select the dimple depth and observe it (record the depth) and go dawn with it by very small depth and when reached the desired dimple depth at that time you can know the depth and the thickness of your sample. Also with much observation and much work with this field with the type of some kind of sample you will appreciate the depth which you want but with some careful once dimpling has begun.
Good luck is very default work steps with the starting users
I also did not get your question completely...
Are you asking about measuring ex-situ - while dimpling, or measuring the final thickness in the TEM?
For the case of dimple thickness control while processing:
if on silicon - there is a color table relating the color of Si to it's thickness, works nicelly below 10um thickness;
if not on Si - you have to find a transparent piece in the middle of the dimple, a thick glue line will make a deal, and look on it under high resolution light microscope with the highest possible NA - these guys have very small focus depth, so it is possible to focus on the front and back faces of the sample separately. Then the difference gives you the value you need.
If you are interested in measuring the final thickness in TEM, than either EELS will work as suggested by Volker (you need to know the composition exactly) or a more simple trick - you focus the beam to the smalles possible spot and deposit the contamination (this happens from both sides). Then tilting the sample to a known angle and measuring the distance between front and back spots should give you the thickness, provided that you can do a simple math :)
Hi! I use a stable, characteristic X-ray source (Cu K alpha) and map the sample in transmission geometry using glassy carbon or a semi-transparent beamstop. To get the absolute sample thickness you have to know your absorption coefficient of course.
Dear Aleksei,
if you are just looking for a quick and easy method to check the dimple depth just use a light microscope. Just focus the top egde of the dimple and then focus the ground of the dimple by changing the high of the sample table. The difference in hight is the depth of the dimple. According to the depth of field of your objective lens (0.5...5µm) this is more precise than the thickness control of a dimple grinder that may fluctuate up to 10µm during polishing.
Best
Martin
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