Question
Asked 20th Nov, 2015

Can I do a XPS depth profile for a a 500 Micrometer thick sample?

I have a 500 Micrometer thick sample and I would like to do a depth profile by XPS is it possible for such a thickness ?

Most recent answer

20th Oct, 2020
Huseyin Ekinci
University of Waterloo
I am confused with the different rates mentioned here for the Ar ion sputter cleaning (etch rate). Can someone clarify this please? Does this etch rate depend on the material e.g. Cr and Cr2O3 surfaces would be etch in different rates?

Popular Answers (1)

24th Nov, 2015
Yuriy Kudriavtsev
Center for Research and Advanced Studies of the National Polytechnic Institute
Hi Elaf,
500 microns is too high for any ion sputtering technique. The typical ion sputter rate is less than 10 A/sec, you can calculate yourself the time necessary... But there is a simple method: to prepare a cross section of the sample. You can prepare section mechanically (cut and polish) or by FIB. Then you can use different analytical techniques for the line scan analysis over the section.
The simplest way will be to use EDX system (EDX/SEM): for elements starting from Na (from C for new generation EDX) you can perform the quantitative analysis with sensitivity up to 0.1% and lateral resolution of around 1 micron (the resolution can be improved by decrease of the electron energy down to 5keV o just to 3keV in a favorite case). If you prepare a transparent cross section for high energy electrons (200keV), you can do the line scan analysis with TEM/EDX system with lateral resolution around 50-100nm.
If you need light element analysis (O,C, N, Li, Be....), you can use AES (down to 10nm lateral resolution), >1% sensitivity. Micro-XPS is possible (3-5 microns of the lateral resolution and chemical analysis with up to 0.1% sensitivity), but this is a new generation system (with micro-capilar X-ray optics), it could be difficult to find the system itself.
For more sensitive analysis you can use TOF-SIMS with the lateral resolution up to 100nm and the sensitivity in the ppm level.
Regards
3 Recommendations

All Answers (11)

20th Nov, 2015
Pablo Forlam Ribeiro Batista
Centro Federal de Educação Tecnológica de Minas Gerais
In theory, yes. However, typical values of sputtering are about 0,1 A/min. You will need a long time to do so. XPS is a surface analysis technique with atomic monolayer resolution. 500 micrometers can be considered bulk, not suface and I don´t think you need information in atomic resolution along 500 micrometers. I recommend the use of other techniques. I hope it was useful. 
1 Recommendation
20th Nov, 2015
Samir Al-Hilfi
The University of Manchester
Thanks Pablo can please suggest other technique .
21st Nov, 2015
Atilla Atli
École Catholique d'Arts et Métiers
I am not sure to understand the answer above. As far as I remember, XPS is a nondestructive surface technique. Sometimes, it is possible to observe the surface modification under classical X-Ray source like desorption if the adsorbate species are studied. But for a bulk material it is very difficult to sputter the surface. 
What kind of information do you need? Composition, crystal structure, chemical state of elements,....?
If you want absolutely to use XPS for depth profile, you can sputter (gun used for surface cleaning in a UHV vacuum chamber) the surface and then perform the XPS. And repeat the sputtering-XPS analysis up to 500 µm. But you need to know the sputtering rate and you have to be sure that the sputtering doesn't modifiy the properties. 
You can also use different angles in order to check the profile up to 10-15 nm of depth (escape depth of electrons) .      
Other technique that you can use is SIMS or combined SIMS-XPS.      
24th Nov, 2015
Pablo Forlam Ribeiro Batista
Centro Federal de Educação Tecnológica de Minas Gerais
The Glow Discharge Optical Emission Spectrometry can provide you a bulk depth profile, but I don´t know much about this technique.  
24th Nov, 2015
Robert Temperton
Lund University
I would also recommend ToF-SIMS. The sputter sources in those instruments are often very capable of sputtering through thick films in manageable time scales. Does not give quite the same information as XPS can but depending on your requirements it may provide the information you require. As others have suggested, people have combined the two but I have no experience with that. 
24th Nov, 2015
Yuriy Kudriavtsev
Center for Research and Advanced Studies of the National Polytechnic Institute
Hi Elaf,
500 microns is too high for any ion sputtering technique. The typical ion sputter rate is less than 10 A/sec, you can calculate yourself the time necessary... But there is a simple method: to prepare a cross section of the sample. You can prepare section mechanically (cut and polish) or by FIB. Then you can use different analytical techniques for the line scan analysis over the section.
The simplest way will be to use EDX system (EDX/SEM): for elements starting from Na (from C for new generation EDX) you can perform the quantitative analysis with sensitivity up to 0.1% and lateral resolution of around 1 micron (the resolution can be improved by decrease of the electron energy down to 5keV o just to 3keV in a favorite case). If you prepare a transparent cross section for high energy electrons (200keV), you can do the line scan analysis with TEM/EDX system with lateral resolution around 50-100nm.
If you need light element analysis (O,C, N, Li, Be....), you can use AES (down to 10nm lateral resolution), >1% sensitivity. Micro-XPS is possible (3-5 microns of the lateral resolution and chemical analysis with up to 0.1% sensitivity), but this is a new generation system (with micro-capilar X-ray optics), it could be difficult to find the system itself.
For more sensitive analysis you can use TOF-SIMS with the lateral resolution up to 100nm and the sensitivity in the ppm level.
Regards
3 Recommendations
24th Nov, 2015
Louis Scudiero
Washington State University
Obtaining Chemical information as a function of depth is routinely done with XPS and it is called depth profiling.  Most XPS instruments are equipped with an Ar ion gun sputtering system that will allow you to do that. Sequencing sputtering and data acquisition of any one or more elements of interest.
However, the thickness of the sample is important because some ion guns are not built to generate high current density beams and it will take a long time to go through the 0.5 mm film. It is feasible with an appropriate ion gun.
25th Nov, 2015
Benjamin T. Young
Rhode Island College
It also matters what you mean by depth profile.  How deep, for instance changes the answer.  For a few angstroms you can, in principle, change the emission angle relative to the analyzer.  If you want to get information up to a few nanometers, you can change the incident photon energy, depending on what you have available.  Synchrotron radiation can give you a different mean escape depth for the photoelectrons on the order of 10 nm.  Beyond that, neutron reflectometry would be one pretty good alternative.
28th Nov, 2015
Saulius Kaciulis
Italian National Research Council
As it was already said, use GDOES for profiling. Otherwise, you can prepare the polished cross-section and study it by using XPS, AES or SIMS.
1 Recommendation
28th Nov, 2015
Samir Al-Hilfi
The University of Manchester
Thank you all for your helpful answers and suggestions . The 500 Micron thick metal thick substrate has a carbon diffuse in so I would like to see how the carbon diffuse from surface to surface .I've tried using EDX but it is not accurate because the contamination from the pump (carbon come from the pump oil). Moreover I'm not quite sure if few nanometre XPS etching depth profile is enough to give an indication for the diffusion manner of carbon inside the substrate. I will try using the Angle resolved XPS depth profile and I have no idea how accurate it is ?. If any one have please back to me.
Thanks all

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