Specific Process Knowledge/Characterization/Element analysis: Difference between revisions

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 </gallery>
-== Secondary Ion Mass Spectrometry (SIMS) ==
+=== Spatial resolution using EDX ===
+Using the the very fine beam of electrons from a SEM one is capable of making point-like elemental analysis of the sample. A multiple scattering process will occur when the incident electrons collide with the sample electrons. This process generates low energetic secondary electrons and it continues until the incident electrons have lost so much energy that they are not different from the secondary electrons. The volume of the sample inside which this process takes place is called the interaction volume. X-rays are generated throughout the interaction volume and we are therefore probing the whole volume when using the EDX detector.
+Using some empirical equations one can calculate how the distribution of X-rays generated in the sample will be at certain high voltages. Below are shown the depth profiles of X-rays from silicon and gold when irradiated with 5-30 kV electrons.
-In the Atomika SIMS the samples are bombarded with a beam of either oxygen or caesium ions. When accelerated to high energy and rastered across the sample
+<gallery caption="Curves that show the depth of origin of the X-rays"
-these ions will be able to gradually sputter off the surface atoms in a small area defined by the raster pattern. Some of the surface atoms are emitted as ionized particles. In this way one layer after another is peeled off the sample.
+widths="300px" heights="300px" perrow="2">
+image:SiX-rayemission.jpg|The depth profiles of X-rays emerging from bulk silicon at different high voltages.
+image:AuX-rayemission.jpg|The depth profiles of X-rays emerging from bulk gold at different high voltages.
+</gallery>
-These charged species are led through a mass spectrometer where a magnetic field is used to deflect them. The deflection increases with charge and decreases with mass and we are therefore able detect and count them according to their mass. This technique is called Secondary Ion Mass Spectrometry or SIMS.
+It is seen that the trend is:
+* Increasing the high voltage gives rise to a bigger and deeper interaction volume and hence increases the depth which is probed.
+* Increasing the density of the sample material reduces the size and depth of the interaction volume - hence a more shallow layer is probed.
-== X-ray Photoelectron Spectroscopy analysis ==
-During a XPS (X-ray Photoelectron Spectroscopy) analysis, the sample is irradiated with photons of a specific energy (in the Danchip system 1486 eV). When energy of the irradiating X-rays is adsorbed by the atoms in the sample, photoelectrons are ejected [[http://en.wikipedia.org/wiki/Photoelectric_effect]].
-Since the energy of the incoming photons is known, and the energy of the ejected electrons is measured, the binding energy of the electrons in the probed atoms can be determined. The binding energy of the electrons are element specific, and is therefore a "finger-print" of the atom. Hence, a measurement of the XPS spectrum gives information of which materials are present in the sample, and at which concentrations.
+== Secondary Ion Mass Spectrometry (SIMS) ==
-XPS is an excellent technique to probe the chemical state of atoms on a surface. The binding energy of lower lying atomic levels (for example 1s, 2s and 2p) are at a specific energy, but is slightly affected by the chemical environment of the probed atom. This is known as the '''chemical shift'''. By measuring the shift of the electron binding energies one can determined the chemical state of atoms. See an example on the page [[Specific Process Knowledge/Characterization/XPS|XPS-ThermoScientific]].
+In the Atomika SIMS the samples are bombarded with a beam of either oxygen or caesium ions. When accelerated to high energy and rastered across the sample
+these ions will be able to gradually sputter off the surface atoms in a small area defined by the raster pattern. Some of the surface atoms are emitted as ionized particles. In this way one layer after another is peeled off the sample.
+These charged species are led through a mass spectrometer where a magnetic field is used to deflect them. The deflection increases with charge and decreases with mass and we are therefore able detect and count them according to their mass. This technique is called Secondary Ion Mass Spectrometry or SIMS.
-== Typical application of SIMS ==
+=== Typical application of SIMS ===
 SIMS is the most sensitive technique for elemental composition. It is therefore ideal if you want to check for a contamination.
@@ Line 105: / Line 114: @@
-== Typical applications of XPS ==
+== X-ray Photoelectron Spectroscopy analysis (XPS) ==
+During a XPS (X-ray Photoelectron Spectroscopy) analysis, the sample is irradiated with photons of a specific energy (in the Danchip system 1486 eV). When energy of the irradiating X-rays is adsorbed by the atoms in the sample, photoelectrons are ejected [[http://en.wikipedia.org/wiki/Photoelectric_effect]].
+Since the energy of the incoming photons is known, and the energy of the ejected electrons is measured, the binding energy of the electrons in the probed atoms can be determined. The binding energy of the electrons are element specific, and is therefore a "finger-print" of the atom. Hence, a measurement of the XPS spectrum gives information of which materials are present in the sample, and at which concentrations.
+XPS is an excellent technique to probe the chemical state of atoms on a surface. The binding energy of lower lying atomic levels (for example 1s, 2s and 2p) are at a specific energy, but is slightly affected by the chemical environment of the probed atom. This is known as the '''chemical shift'''. By measuring the shift of the electron binding energies one can determined the chemical state of atoms. See an example on the page [[Specific Process Knowledge/Characterization/XPS|XPS-ThermoScientific]].
+=== Typical applications of XPS ===
 The XPS can be used for different applications, for example:
@@ Line 116: / Line 136: @@
 ** See what effect a surface treatment of your sample has on the surface chemistry.
 ** Check a polymer covered surface. Are for example (C=O), (C-OH) (C-C) groups present in the polymer after it been deposited on a surface.
-== Spatial resolution using EDX ==
-Using the the very fine beam of electrons from a SEM one is capable of making point-like elemental analysis of the sample. A multiple scattering process will occur when the incident electrons collide with the sample electrons. This process generates low energetic secondary electrons and it continues until the incident electrons have lost so much energy that they are not different from the secondary electrons. The volume of the sample inside which this process takes place is called the interaction volume. X-rays are generated throughout the interaction volume and we are therefore probing the whole volume when using the EDX detector.
-Using some empirical equations one can calculate how the distribution of X-rays generated in the sample will be at certain high voltages. Below are shown the depth profiles of X-rays from silicon and gold when irradiated with 5-30 kV electrons.
-<gallery caption="Curves that show the depth of origin of the X-rays"
-widths="300px" heights="300px" perrow="2">
-image:SiX-rayemission.jpg|The depth profiles of X-rays emerging from bulk silicon at different high voltages.
-image:AuX-rayemission.jpg|The depth profiles of X-rays emerging from bulk gold at different high voltages.
-</gallery>
-It is seen that the trend is:
-* Increasing the high voltage gives rise to a bigger and deeper interaction volume and hence increases the depth which is probed.
-* Increasing the density of the sample material reduces the size and depth of the interaction volume - hence a more shallow layer is probed.