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Element analysis at Nanolab

The following techniques for elemental analysis are available at Nanolab.

EDX
SIMS (no longer available at Nanolab, SIMS service can be provided by this company: [1])
XPS (ESCA)

In the table below the three techniques are compared

Comparison of EDX, SIMS and XPS

	SEM with EDX	Atomika SIMS	XPS (or ESCA)
Full name	Energy Dispersive X-ray Analysis	Secondary Ion Mass Spectroscopy	X-ray Photoelectron Spectroscopy (or Electron Spectroscopy for Chemical Analysis)
Technique	The primary beam of high energy electrons used in the SEM for imaging impinges on the sample atoms and leaves them in an excited state. X-rays with a characteristic energy are generated in the relaxation process. The combination of the fine control of the primary beam offered by the SEM and the detection of the X-rays makes it possible to make point-like elemental analysis.	A beam of high energy ions (cesium or oxygen) is used for sputtering off surface atoms of the sample. The material coming off the sample in this process is analysed with a mass spectrometer.	In a process in which a monochromatic beam of X-rays irradiates the sample surface, electrons bound inside the sample are knocked free to become photoelectrons. Escaping the sample with characteristic energy, these electrons not only carry elemental information but also chemical information. Analysing them respect to energy and numbers and adding an ion gun for depth profiles provide a powerful analysis tool.
What elements are detected	Every element heavier than boron/carbon	In principle every element, however, the sensitivity	Every element except hydrogen and helium.
Chemical information	None	None	Chemical state information
Sample requirements	Vacuum compatible	UHV vacuum compatible The sample needs to be cut into small (app. 5*5 mm) pieces.	UHV vacuum compatible Sample size max 50x50 mm, thickness max 20 mm.
Spatial resolution	Very precise point-like analysis is possible with SEM electron beam.	A square with dimensions of a few hundred microns is selected for analyis with a camera	Using a magnified view from a camera, a point that covers an area down to an ellipse of 40 microns may be irradiated with photons (the default size is 400 microns)
Depth resolution	The size of the interaction volume depends on the high voltage in the SEM and the sample density: The higher the SEM high voltage the bigger and deeper the interaction volume. The more dense the material is the smaller is the interaction volume. See section 'Spatial resolution using EDX' below.	The sputtering of the surface makes it possible to perform detailed depth profiling with extremely good sensitivity and depth resolution.	Very surface sensitive technique. Only photoelectrons from the top layer (a few nanometers deep) escape unscattered. By using the ion beam etch, the composition of deeper lying layers can be probed.
Detection limit	Approximately 1 % atomic weight	Down to 1 ppb for certain elements	Approximately 1 % atomic weight
Speed of measurement	Very fast and easy	Time consuming	Quite fast and easy

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-[[image:EDX-scheme.jpg|300x300px|right|thumb|The high energy electrons in the beam (denoted above as incident particle) collide with the core electrons of the sample atoms that are left in an excited state with higher energy. One decay mechanism is to let an outer electron fall into the unoccupied state under emission of a photon that carries the excess energy. This energy is determined by the electronic shells and hence characteristic of the atom.]]
+'''Feedback to this page''': '''[mailto:characterization@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php?title=Specific_Process_Knowledge/Characterization/Element_analysis&action=edit click here]'''
+<!--Checked for updates on 24/8-2021. ok/ jmli-->
-You can make detailed analysis on the elemental composition and distribution in a sample with 3 instruments at Danchip. The [[Specific Process Knowledge/Characterization/SEM: Scanning Electron Microscopy/Leo|Leo SEM]] and [[Specific Process Knowledge/Characterization/SEM: Scanning Electron Microscopy/FEI|FEI SEM]] are both equipped with an X-ray detector that allows you to make elemental analysis by using the technique Energy Dispersive X-ray analysis or EDX. The [[Specific Process Knowledge/Characterization/SIMS: Secondary Ion Mass Spectrometry|Atomika SIMS]] uses a technique called Secondary Ion Mass Spectrometry or SIMS.
-== Energy Dispersive X-ray analysis ==
+= Element analysis at Nanolab =
-The technique of extracting information from the X-rays generated in a sample that is irradiated with electrons is called energy dispersive X-ray analysis or EDX. (Other acronyms are Energy Dispersive x-ray Spectroscopy, EDS, or Electron Probe Microanalysis, EPMA). The energetic electrons in the incident beam create core level vacancies as they collide with sample atoms electrons in a multiple scattering process. This leaves the atoms in the sample in an excited state. In the process of decaying from this state photons may be emitted. The energy of these photons is determined by the difference in energy of the shells involved. Since atomic shells are unique for every element so will be the transitions between them. Thus, every element has its own characteristic X-ray spectrum that can be used to determine the elemental composition.
+The following techniques for elemental analysis are available at Nanolab.
+* EDX
+* SIMS (no longer available at Nanolab, SIMS service can be provided by this company: [http://www.eag.com/secondary-ion-mass-spectrometry-sims/])
+* XPS (ESCA)
+In the table below the three techniques are compared
-Adding an EDX detector to a SEM provides a very powerful tool for elemental analysis. The capability of the SEM to precisely maneuver the electron beam in a number of ways enables us to make point-like analysis with nanometer precision.
+== Comparison of EDX, SIMS and XPS ==
+{| border="2" cellspacing="0" cellpadding="2" align="left"
-== Secondary Ion Mass Spectrometry ==
+!width="100" style="background:silver; color:black" |
+!width="250" style="background:silver; color:black" | SEM with [[Specific Process Knowledge/Characterization/EDX|EDX]]
-[[image:SIMScascade.gif|200x200px|right|thumb|A beam of high energy ions is rastered on the surface of the sample. Some of the atoms that used to make up the surface are sputtered off and emitted as secondary ions. The mass of the these ions is measured with a mass spectrometer.]]
+!width="250" style="background:silver; color:black" | [[Specific Process Knowledge/Characterization/SIMS: Secondary Ion Mass Spectrometry#Atomika_SIMS|Atomika SIMS]]
+!width="250" style="background:silver; color:black" | [[Specific Process Knowledge/Characterization/XPS|XPS]] (or ESCA)
-When a solid sample is sputtered by primary ions of few keV energy, a fraction of the particles emitted from the target is ionized. Secondary Ion Mass Spectrometry consists of analyzing these secondary ions with a mass spectrometer. Secondary ion emission by a solid surface under ion bombardment supplies information about the elemental, isotopic and molecular composition of its uppermost atomic layers.
+|- valign="top"
+! style="background:WhiteSmoke; color:black" width="60" | Full name
-{| border="1" cellspacing="0" cellpadding="4" align="center"
+! style="background:WhiteSmoke; color:black" | Energy Dispersive X-ray Analysis
-!width="100"|
+! style="background:WhiteSmoke; color:black" | Secondary Ion Mass Spectroscopy
-!width="300" | SEM with EDX
+! style="background:WhiteSmoke; color:black" | X-ray Photoelectron Spectroscopy (or Electron Spectroscopy for Chemical Analysis)
-!width="300" | SIMS
+|-
+! style="background:lightgrey; color:black" | Technique
+| style="background:lightgrey; color:black" | The primary beam of high energy electrons used in the SEM for imaging impinges on the sample atoms and leaves them in an excited state. X-rays with a characteristic energy are generated in the relaxation process. The combination of the fine control of the primary beam offered by the SEM and the detection of the X-rays makes it possible to make point-like elemental analysis.
+| style="background:lightgrey; color:black" | A beam of high energy ions (cesium or oxygen) is used for sputtering off surface atoms of the sample. The material coming off the sample in this process is analysed with a mass spectrometer.
+| style="background:lightgrey; color:black" | In a process in which a monochromatic beam of X-rays irradiates the sample surface, electrons bound inside the sample are knocked free to become photoelectrons. Escaping the sample with characteristic energy, these electrons not only carry elemental information but also chemical information. Analysing them respect to energy and numbers and adding an ion gun for depth profiles provide a powerful analysis tool.
 |-
-! Full name
+! style="background:WhiteSmoke; color:black" | What elements are detected
-|| Energy Dispersive X-ray Analysis
+| style="background:WhiteSmoke; color:black" | Every element heavier than boron/carbon
-|| Secondary Ion Mass Spectroscopy
+| style="background:WhiteSmoke; color:black" | In principle every element, however, the sensitivity
-|-
+| style="background:WhiteSmoke; color:black" | Every element except hydrogen and helium.
-!  Technique
-|| Non destructive method: X-rays are generated when the primary beam impinge on the sample. The elemental analysis is possible because the energy of these photons is characteristic of the element they emitted from.
-|| Destructive method: A beam of high energy heavy ions (caesium or oxygen) sputters off surface atoms that are subsequently measured with a mass spectrometer.
 |-
-!  What elements are detected
+! style="background:lightgrey; color:black" | Chemical information
-|| Every element heavier than boron/carbon
+|style="background:lightgrey; color:black"| None
-|| Every element
+|style="background:lightgrey; color:black"| None
+|style="background:lightgrey; color:black"| Chemical state information
 |-
-!  Chemical information
+! style="background:WhiteSmoke; color:black" | Sample requirements
-|| None: Only transistions involving inner shell electrons are detected
+| style="background:WhiteSmoke; color:black" | Vacuum compatible
-|| None
+| style="background:WhiteSmoke; color:black" align="left"|
+* UHV vacuum compatible
+* The sample needs to be cut into small (app. 5*5 mm) pieces.
+| style="background:WhiteSmoke; color:black" align="left"|
+* UHV vacuum compatible
+* Sample size max 50x50 mm, thickness max 20 mm.
 |-
-!  Sample limitations
+! style="background:lightgrey; color:black" | Spatial resolution
-|| Vacuum compatible.
+|style="background:lightgrey; color:black"| Very precise point-like analysis is possible with SEM electron beam.
-|| Vacuum compatible. The sample needs to be cut into small pieces.
+|style="background:lightgrey; color:black"| A square with dimensions of a few hundred microns is selected for analyis with a camera
+|style="background:lightgrey; color:black"| Using a magnified view from a camera, a point that covers an area down to an ellipse of 40 microns may be irradiated with photons (the default size is 400 microns)
 |-
-!  Spatial resolution
+! style="background:WhiteSmoke; color:black" | Depth resolution
-|| Very precise point-like analysis is possible with SEM electron beam.
+| style="background:WhiteSmoke; color:black" | The size of the interaction volume depends on the high voltage in the SEM and the sample density: The higher the SEM high voltage the bigger and deeper the interaction volume. The more dense the material is the smaller is the interaction volume. See section 'Spatial resolution using EDX' below.
-|| Limited to what is visible in a camera
+| style="background:WhiteSmoke; color:black" | The sputtering of the surface makes it possible to perform detailed depth profiling with extremely good sensitivity and depth resolution.
+| style="background:WhiteSmoke; color:black" | Very surface sensitive technique. Only photoelectrons from the top layer (a few nanometers deep) escape unscattered. By using the ion beam etch, the composition of deeper lying layers can be probed.
 |-
-!  Depth resolution
+! style="background:lightgrey; color:black" | Detection limit
-|| The size interaction volume depends on the SEM high voltage and sample density: The higher the SEM high voltage the bigger and deeper the interaction volume. The more dense the material is the smaller is the interaction volume.
+|style="background:lightgrey; color:black"| Approximately 1 % atomic weight
-|| The sputtering of the surface makes it possible to perform detailed depth profiling with extremely good sensitivity and depth resolution.
+|style="background:lightgrey; color:black"| Down to 1 ppb for certain elements
+|style="background:lightgrey; color:black"| Approximately 1 % atomic weight
 |-
-!  Detection limit
+! style="background:WhiteSmoke; color:black" | Speed of measurement
-|| Approximately 1 % atomic
+| style="background:WhiteSmoke; color:black" | Very fast and easy
-|| Down to 1 ppb for many elements
+| style="background:WhiteSmoke; color:black" | Time consuming
+| style="background:WhiteSmoke; color:black" | Quite fast and easy
 |}