Ion sputtering
Ion sputtering is used for sample cleaning from adsorbates or deposits. If you do not have yet your optimized sample cleaning procedure you can look for information in
Musket's article.
There are in total three sputter ion guns with corresponding Ar bottles, leak valves and gas inlets. In the analysis chamber we mostly use the
main gun mounted above the inlet of the synchrotron light. If it breaks there is a
backup gun mounted below the quadrupole mass spectrometer, close to the electron analyzer. The third ion gun is in the preparation chamber - bottom, above the turbomolecular pump.
There are also three similar power supplies and three cables, labelled #1-#3. All devices are compatible so before ion sputtering carefully observe the labels in order to know which power supply controls which gun.
The difference in the power supplies is that #1 has has the filament switch on the rear panel and the beam energy is indicated only by the scale on the corresponding knob, while others (#2, #3) have the filament switch and beam energy indicator on the front panel.
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Analysis chamber
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Check that LEED, electron analyzer, X-ray source, evaporators, titanium sublimation pump etc. are off and that all gate valves to other chambers (also the electropneumatic valve 10 towards the beamline) are properly closed and that the fan on the ion gun is on.
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Set the sample position (for the main ion gun approximately x = 25, y = 20, z = 244, Θ = 195° for sputtering angle 45°; for the backup ion gun change x = 30, y = 15).
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Open the Ar leak valve on the connected ion gun to set the pressure in the chamber to 2×10-6 mbar.
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Switch on the correct power supply.
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Set the emission to 14 mA using the emission knob. At the beginning the indicator will not react, then it will jump as the feedback loop is synchronized.
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Switch on beam energy and adjust the energy by the knob if necessary (usually we use 1 keV).
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Start the timer for the desired sputtering time (usually 10-60 minutes). During the sputtering adjust the pressure if needed.
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Switch off the beam energy, set emission to zero, switch off the power supply.
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Close the Ar leak valve without forcing it. Wait for the pressure in the chamber to recover.
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Preparation chamber - bottom
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Check that all sensitive instruments (evaporators, titanium sublimation pump) in the chamber are off and that all gate valves to other chambers are properly closed.
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Move the sample on the transfer rod approximately to the centre of the chamber. Rotate the transfer rod to have the sample either horizontally or vertically for sputtering angle 45°.
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Open the Ar leak valve to set the pressure in the chamber to 5×10-6 mbar.
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Switch on the power supply.
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Set the emission to 14 mA using the emission knob. At the beginning the indicator will not react, then it will jump as the feedback loop is synchronized.
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Switch on beam energy and adjust the energy by the knob if necessary (usually we use 1 keV).
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Start the timer for the desired sputtering time (usually 10-60 minutes). During the sputtering adjust the pressure if needed.
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Switch off the beam energy, set emission to zero, switch off the power supply.
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Close the Ar leak valve without forcing it. Wait for the pressure in the chamber to recover.
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Based on the tests on CeO
2(111)/Cu(111) thin films (January 2022) the sputtering rate at 14 mA emission is
0.25 nm/min (at 500 eV) and
0.5 nm/min (at 1 keV). Based on the tests on CoO/Ir(100) thin films (May 2023) the sputtering rate at 14 mA emission is
1 nm/min (at 1 keV). The ion currents measured on samples well electrically insulated from the manipulator are about 1-10 μA (tested January 2023).
Ultima modifica il Lunedì, 12 Giugno 2023 13:48