Specific Process Knowledge/Characterization/XPS: Difference between revisions

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Unless otherwise stated, all content on this page was created by Jonas Michael-Lindhard, DTU Nanolab

The XPS tools at DTU Nanolab

The K-Alpha from 2007 is one of the first instruments of this type that was produced.Photo: DTU Nanolab internal

The Nexsa from 2019 is on the surface very similar to the K-Alpha. Its panels, however, hide a whole range of supplementary techniques.Photo: DTU Nanolab internal

In the basement under the cleanroom two X-ray Photoelectron Spectroscopy (XPS) systems are installed back-to-back in the center of room 904. They are both manufactured by Thermofisher and they enable the users to perform elemental and chemical analysis of samples. The XPS K-Alpha is a base technique instrument providing XPS analysis. The XPS Nexsa is an upgraded version with all options.

Elemental analysis

The XPS instrument enables elemental analysis, chemical state analysis on the sample surface or deeper down by a depth profiling. A comparison about techniques and instruments used for elemental analysis at DTU Nanolab can be found on the page Element analysis.

More about the different possibilities of the XPS instrument is found here:

Getting access to the XPS tools

Click HERE to see information on how to get access to the XPS.

Analyzing XPS spectra

The analysis of XPS spectra is an art in itself. It can be done using various software packages available on the internet. In the links below we will focus on two such examples, Avantage and CasaXPS.

Techniques and option on the XPS tools

Equipment		XPS K-Alpha (Manufactured by Thermofisher)	XPS Nexsa (Manufactured by Thermofisher)
Purpose	Main	XPS analysis using monochromated Al-Kα radiation at 1486.6 eV	XPS analysis using monochromated Al-Kα radiation at 1486.6 eV
Purpose	Alternative/complementary	Work function measurements	Work function measurements Ultraviolet Photoelectron Spectroscopy (UPS) with He I and He II UV source Ion Scattering Spectroscopy or ISS Reflected Electron Energy Loss Spectroscopy or REELS Angular Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS) Raman spectroscopy
Performance	Spot size	XPS: 30µm - 400µm	XPS: 10µm - 400µm Raman: > 15 µm
	Pass energy	10-400 eV	10-400 eV (XPS and ISS)
	Analysis modes	Scanned and snapshot	Scanned, snapshot and SnapMap
	Charge compensation	Flood gun to be used for charge compensation of non conductive samples only	Flood gun to be used for charge compensation of non conductive samples and for source of low energy electrons (REELS)
	Depth profiles	Depth profiles with single Ar ion bombardment Monoatomic energy range 200-3000 eV	Depth profiles with MonoAtomic and Gas Cluster Ion Source (MAGCIS) Monoatomic energy range 200-4000 eV Cluster mode energy range: 2-8 keV Cluster size range: 75-2000 atoms
Substrates / Samples	Sample holder size	Maximum 60x60 mm	Maximum 60x60 mm
Substrates / Samples	Sample height	Maximum 20 mm	Maximum 20 mm

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+'''Unless anything else is stated, everything on this page, text and pictures are made by DTU Nanolab.'''
-'''Feedback to this page''': '''[mailto:characterization@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php?title=Specific_Process_Knowledge/Characterization/XPS click here]'''
+'''All links to Kemibrug (SDS) and Labmanager Including APV and QC requires login.'''
+'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php?title=Specific_Process_Knowledge/Characterization/XPS click here]'''
+<!--Checked for updates on 14/5-2018 - ok/jmli -->
+{{Template:Author-jmli1}}
-==XPS-ThermoScientific==
+==The XPS tools at DTU Nanolab==
-[[image:XPS instrument2.JPG|300x300px|right|thumb|The XPS system placed at Danchip (room 904, building 346).]]
+[[Image:XPS K-Alpha.jpg |frame|x300px|The K-Alpha from 2007 is one of the first instruments of this type that was produced.{{photo1}} ]]
+[[Image:XPS Nexsa.png |frame|x300px|The Nexsa from 2019 is on the surface very similar to the K-Alpha. Its panels, however, hide a whole range of supplementary techniques.{{photo1}} ]]
-A X-ray Photoelectron Spectroscopy (XPS) system can be used at Danchip. The system is a Thermo K-Alpha system, placed in the basement of building 346.
+In the basement under the cleanroom two X-ray Photoelectron Spectroscopy (XPS) systems are installed back-to-back in the center of room 904. They are both manufactured by Thermofisher and they enable the users to perform elemental and chemical analysis of samples. The [[Specific Process Knowledge/Characterization/XPS/K-Alpha |XPS K-Alpha]] is a base technique instrument providing XPS analysis. The [[Specific Process Knowledge/Characterization/XPS/Nexsa |XPS Nexsa]] is an upgraded version with all options.
+* [[Specific Process Knowledge/Characterization/XPS/K-Alpha|The XPS K-Alpha page]]
+* [[Specific Process Knowledge/Characterization/XPS/Nexsa|The XPS Nexsa page]]
-'''The user manual(s), user APV(s), technical information and contact information can be found in LabManager:'''
-<!-- remember to remove the type of documents that are not present -->
-<!-- give the link to the equipment info page in LabManager: -->
-[http://http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=276  XPS-ThermoScientific in LabManager]
 ==Elemental analysis==
-The XPS technique can be used to do elemental analysis. A comparison about techniques and instruments used for elemental analysis at Danchip can be found on the page [[Specific Process Knowledge/Characterization/Element analysis|Element analysis]].
+The XPS instrument enables elemental analysis, chemical state analysis on the sample surface or deeper down by a depth profiling. A comparison about techniques and instruments used for elemental analysis at DTU Nanolab can be found on the page [[Specific Process Knowledge/Characterization/Element analysis|Element analysis]].
-==XPS technique==
+More about the different possibilities of the XPS instrument is found here:
+*[[Specific Process Knowledge/Characterization/XPS/XPS technique|The XPS technique]]
+*[[Specific Process Knowledge/Characterization/XPS/XPS elemental composition|Elemental analysis]]
+*[[Specific Process Knowledge/Characterization/XPS/XPS Depth profiling|Depth profiling]]
+*[[Specific Process Knowledge/Characterization/XPS/Carbon contamination|Carbon contamination]]
-XPS is a surface sensitive and non destructive technique used for analysis of the elemental composition.
+*[[Specific Process Knowledge/Characterization/XPS/ExtDocs | Links to external material ]]
-Only the outermost atomic layers (some nanometers) are probed, but with an ion gun etch it is possible to probe deeper laying layers.
+*[[Specific Process Knowledge/Characterization/XPS/Training | Links to instruction videos ]]
+== Getting access to the XPS tools==
-In the XPS spectrometer system the probed samples are irradiated by photons with a specific energy, and the photoelectrons that leaves the sample are detected. The energy levels of the electrons are elemental specific, and by measuring the energy of the outgoing electrons, it is possible to detect which elements that are present in a sample.
+Click [[Specific Process Knowledge/Characterization/XPS/Access | '''HERE''' ]] to see information on how to get access to the XPS.
-You can read further about the technique here: [http://en.wikipedia.org/wiki/X-ray_photoelectron_spectroscopy]
+== Analyzing XPS spectra ==
+The analysis of XPS spectra is an art in itself. It can be done using various software packages available on the internet. In the links below we will focus on two such examples, Avantage and CasaXPS.
+*[[Specific Process Knowledge/Characterization/XPS/SoftwareInstall|How to access XPS software: Download/install or by access to server]]
+*[[Specific Process Knowledge/Characterization/XPS/Processing|Processing XPS data with Avantage]]
+*[[Specific Process Knowledge/Characterization/XPS/Export2CasaXPS | Export Avantage data to CasaXPS]]
-The technique can be used for different purposes:
+==Techniques and option on the XPS tools==
+{| border="2" cellspacing="0" cellpadding="1"
+|-
+!style="background:silver; color:black;" align="left" colspan="2"|Equipment
+!style="background:silver; color:black;" align="left" |[[Specific Process Knowledge/Characterization/XPS/K-Alpha |XPS K-Alpha (Manufactured by Thermofisher)]]
+!style="background:silver; color:black;" align="left" |[[Specific Process Knowledge/Characterization/XPS/Nexsa |XPS Nexsa (Manufactured by Thermofisher)]]
+|-
+!style="background:silver; color:black;" align="left" rowspan="2"|Purpose
+|style="background:LightGrey; color:black"|Main
+|style="background:WhiteSmoke; color:black"| XPS analysis using monochromated Al-Kα radiation at 1486.6 eV
+|style="background:WhiteSmoke; color:black"| XPS analysis using monochromated Al-Kα radiation at 1486.6 eV
+|-
-===Elemental composition===
+|style="background:LightGrey; color:black"|Alternative/complementary
-[[image:Overview spectra Labadvisor.JPG|420x420px|left|thumb|XPS spectrum of a sample consisting of the elements silicon, oxygen and carbon.]]
-Each element give a specific "finger-print" in the XPS spectrum. The binding energy of the electrons in atoms are different for all elements, and when measuring a photoelectron spectrum over a wide range of energies, the main line from each element will be placed at a specific energy in the spectrum.
-Here is shown a spectrum measured over the energy range 0-1350 eV, and characteristic lines from three elements (C,O and Si) are seen and indicated in the spectrum.
-The instrument program can use this information to give an estimate of the sample composition, giving the atomic percentage of the different elements.
-===Chemical state===
-[[image:Si2p.JPG|420x420px|left|thumb|XPS Si2p spectrum of a Si reference sample (red curve), and a Si sample that was treated in HF shortly before the measurement was done (green curve). ]]
-Due to the so called chemical shift, it is possible to get information about the chemical state of the probed atoms.
-The core electrons of the atoms are affected, meaning that the binding energy of the electrons are slightly shifted, when an atom is bonded to atoms of other elements.
-This gives an excellent tool for examining the chemistry of a surfaces, and how it is affected by different surface treatments.
-The figure to the left gives an illustration of the effect. An XPS Si2p spectrum of a Si reference sample and a Si sample that was treated in HF shortly before the measurement, is clearly showing two different curves. The untreated spectrum has a clear feature at about 103 eV due to Si atoms bonded to oxygen. In the spectrum from the HF treated sample, only the feature steaming from Si-Si interaction is present. Note that both curves only shows the Si signal, but with an clear indication of the chemical state of the Si atoms in the samples.
-If you study polymers, you can detect the presence of different chemical groups, for example (C-C),(C-OH),(C=O),(CF3) or (CF2-CH2) in the polymeric layer. And after surface treatments, you may examine differences in the polymeric layer.
-Note that binding energies for different chemical states often can be found in the literature.
-===Depth profiling===
-[[Image:Stochiometry 20110510.JPG|425x425px|left|thumb|The composition of a NiCr as a function of film depth (etch time). The relationship between Cr and Ni is quite constant through the 70nm thick film. Measurements done with XPS-ThermoScientific. ]]
-The analysis is made on a chosen spot on the sample surface (chosen with the system camera). The technique is, as written above, very surface sensitive and probes only the top nanometers of the sample.
-With the ion beam gun on the system an etch of the sample can be done. The system measures the desired spectrum, does an etch step and measures again. A series of etch cycles can be set up, measuring the composition of the sample at different depths (for example at different depth of a film).
-'''Example: NiCr film'''
-As an illustration, a figure to the left, shows an elemental analysis through a metallic film consisting of Ni and Cr. The metallic layer was about 70 nm thick, and the atomic percentage of Ni and Cr was measured through the layer.
-In the graph, you see the atomic % as a function of etch depth, and it is possible to detect that the relationship between Ni and Cr is fairly constant through the metallic film.
-==Equipment performance of XPS-ThermoScientific==
-{| border="2" cellspacing="0" cellpadding="20" |-
-!style="background:silver; color:black;" align="left"|Purpose
-|style="background:LightGrey; color:black"|Chemical analysis
 |style="background:WhiteSmoke; color:black"|
-* Probing elemental composition
+* Work function measurements
-* Chemical state identification
+|style="background:WhiteSmoke; color:black"|
-* Non destructive technique
+* Work function measurements
-* Surface sensitive
+* [[Specific Process Knowledge/Characterization/XPS/UPS technique| Ultraviolet Photoelectron Spectroscopy (UPS) with He I and He II UV source]]
-* Depth profiling possible by ion beam etch of sample
+* [[Specific Process Knowledge/Characterization/XPS/ISS|Ion Scattering Spectroscopy or ISS]]
+* [[Specific Process Knowledge/Characterization/XPS/REELS|Reflected Electron Energy Loss Spectroscopy or REELS]]
+* Angular Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS)
+* [[Specific Process Knowledge/Characterization/XPS/Raman|Raman spectroscopy]]
 |-
 !rowspan="5" style="background:silver; color:black" align="left"| Performance
 |style="background:LightGrey; color:black"|Spot size
-|style="background:WhiteSmoke; color:black"|Can be set between 30µm - 400µm
+|style="background:WhiteSmoke; color:black"|XPS: 30µm - 400µm
+|style="background:WhiteSmoke; color:black"|
+* XPS: 10µm - 400µm
+* Raman: > 15 µm
 |-
-|style="background:LightGrey; color:black"|Probing depth
+|style="background:LightGrey; color:black"|Pass energy
-|style="background:WhiteSmoke; color:black"|Depending on probed element. Max probe depth lies within 10-200 Å.
+|style="background:WhiteSmoke; color:black"|10-400 eV
+|style="background:WhiteSmoke; color:black"|10-400 eV (XPS and ISS)
 |-
-|style="background:LightGrey; color:black"|Resolution
+|style="background:LightGrey; color:black"|Analysis modes
-|style="background:WhiteSmoke; color:black"|Dependent on probed elements. Concentrations down to about 0,5 atomic % can in some cases be detected.
+|style="background:WhiteSmoke; color:black"|Scanned and snapshot
+|style="background:WhiteSmoke; color:black"|Scanned, snapshot and SnapMap
 |-
 |style="background:LightGrey; color:black"|Charge compensation
-|style="background:WhiteSmoke; color:black"|
+|style="background:WhiteSmoke; color:black"| Flood gun to be used for charge compensation of non conductive samples only
-Flood gun can be used for charge compensation of non conductive samples
+|style="background:WhiteSmoke; color:black"| Flood gun to be used for charge compensation of non conductive samples and for source of low energy electrons (REELS)
-|-
-|style="background:LightGrey; color:black"|Finding structures
-|style="background:WhiteSmoke; color:black"|Choose measuring spot from camera image (magnified)
-|-
-|-
-|-
-!rowspan="2" style="background:silver; color:black" align="left"|Depth profiling
-|style="background:LightGrey; color:black"|Purpose
-|style="background:WhiteSmoke; color:black"|With ion beam etch the top layer of the material can be removed, to do a depth profiling
 |-
-|style="background:LightGrey; color:black"|Ion beam size
+|style="background:LightGrey; color:black"|Depth profiles
-|style="background:WhiteSmoke; color:black"| About 0,3x1 mm
+|style="background:WhiteSmoke; color:black"|Depth profiles with single Ar ion bombardment
+* Monoatomic energy range 200-3000 eV
+|style="background:WhiteSmoke; color:black"|Depth profiles with MonoAtomic and Gas Cluster Ion Source ([[Media:MAGCIS.pdf |MAGCIS]])
+* Monoatomic energy range 200-4000 eV
+* Cluster mode energy range: 2-8 keV
+*Cluster size range: 75-2000 atoms
 |-
-!rowspan="2" style="background:silver; color:black" align="left"|Substrates
+!rowspan="2" style="background:silver; color:black" align="left"|Substrates / Samples
-|style="background:LightGrey; color:black"|Substrate size
+|style="background:LightGrey; color:black"|Sample holder size
-|style="background:WhiteSmoke; color:black"|
+|style="background:WhiteSmoke; color:black"| Maximum 60x60 mm
-Max 60x60 mm
+|style="background:WhiteSmoke; color:black"| Maximum 60x60 mm
 |-
-| style="background:LightGrey; color:black"|Substrate thickness
+| style="background:LightGrey; color:black"|Sample height
-|style="background:WhiteSmoke; color:black"|
+|style="background:WhiteSmoke; color:black"| Maximum 20 mm
-Max height about 20 mm
+|style="background:WhiteSmoke; color:black"| Maximum 20 mm
 |-
 |}