Specific Process Knowledge/Thin film deposition/Temescal: Difference between revisions
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[[File:Sell_quartz_crystal_microbalance.jpg|100px|right|thumb|Quartz crystal microbalance with gold electrode. Image from RLC on EC21.com]] | [[File:Sell_quartz_crystal_microbalance.jpg|100px|right|thumb|Quartz crystal microbalance with gold electrode. Image from RLC on EC21.com]] | ||
The thickness calculation depends on the material density as well as other physical factors. A | The thickness calculation depends on the material density as well as other physical factors. A ''tooling factor'' is used to adjust the calculation based on the geometry of the setup, since the crystal is not in the same place as the wafers so the thickness deposited on the crystal is lower than on the samples. | ||
The tooling factor is calibrated for a particular deposition rate. It may not be perfectly accurate for other deposition rates, but should easily be within the 10 % accuracy that we test for in our quality control measurements. | The tooling factor is calibrated for a particular deposition rate. It may not be perfectly accurate for other deposition rates, but should easily be within the 10 % accuracy that we test for in our quality control measurements. | ||
For very thin films the thickness measurement will be less accurate than for thicker films. | For very thin films the thickness measurement will be less accurate than for thicker films. | ||
The machine gives a rough number for the crystal lifetime simply based on how thick a layer it calculates has been deposited on it. If many layers have been deposited and there is stress in the layers (e.g., in Cr | The machine gives a rough number for the crystal lifetime simply based on how thick a layer it calculates has been deposited on it. If many layers have been deposited and there is stress in the layers (e.g., in Cr or Ni), there may be partial delamination, which can make the thickness measurement inaccurate. In this case the lifetime estimate given by the machine will be inaccurate. If you think the crystal is not measuring correctly, please let us know. We exchange the crystals usually around 20 % lifetime use. | ||
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== Heating during deposition == | == Heating during deposition == | ||
If the material you are depositing requires a lot of heat to evaporate, the substrates may get warm during the deposition. | If the material you are depositing requires a lot of heat to evaporate, the substrates may get warm during the deposition. | ||