Al2O3 thin films, either amorphous or of varying degrees of crystallinity, were deposited by two-frequency radio-frequency magnetron sputtering. Film crystallinity was investigated by Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) was employed to determine the amount of Ar naturally trapped within the films during the deposition process. A clear correlation was found between the existence of crystalline phases, as determined by XRD, and a shift towards lower binding energy positions of the Ar2p core levels of embedded gas. The shift is due to differences in the local Al2O3 matrix (amorphous or crystalline) of the embedded gas, thus providing an XPS fingerprint that can be used to qualitatively determine the presence or absence of crystalline phases in very thin films.
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|Plasma Source Name|
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|Plasma Source Specification|
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Multi frequency CCP with 71MHz and 13.56 MHz at the driving electrode. Magnetron configuration within driving electrode including an Al target.
English (United Kingdom)
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Plasma ignition with both frequencies at driving electrode, substrate electrode biased with 1.01MHz (rectangular). Si substrates were heated up to 600°C for deposition of Al2O3. The plasma was ignited with 9 sccm continuous Ar flow and an oxygen flow, which was set with a feedback loop due to possible target poisoning. Plasma deposition was done until a maximum layer thickness of 1µm was reached.
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The mean oxygen partial pressure was 8.6 x 10^(-3) Pa (total working pressure was 0.13 Pa). The gas flow rate for Ar: 9sccm, oxygen flow was set with a feedback loop. Here the oxygen concentration within the plasma was detected with an optical filter observing the Al emission line at 396nm. The intensity of this emission line was measured by a photomultiplier. An oxygen flow was set with the help a LabView program calculating the optimum flow rate into the chamber using a feedback loop.
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Gas flow was set directly before ignition of the plasma.
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The Si wafer was cut into 2.5cm x 2.5cm large pieces and mounted to the sample holder.
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Si wafer was mounted to the sample holder, inserted to the chamber and heated up to the desired temperature. The temperature was detected with an ellipsometer.
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Photomultiplier detecting the intensity of the Al I emission line at 396nm
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Data and Resources
- Figure 1: grazing incidence XRDcsv
XRD was realized under grazing incidence using a Bruker D8 General Area...
- Figure 2: FTIR transmission functioncsv
FTIR transmission measurements of the s-polarized component were performed...
- Figure 3: XPS analysiscsv
The measurements were performed with a Versaprobe spectrometer from Physical...