Specific Process Knowledge/Thin film deposition/Deposition of Aluminium/Thermal deposition of Al
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Thermal evaporation of Aluminum
Aluminum can be thermally evaporated in Wordentec. At DTU Danchip, we recommend to use a thin layer of thermally evaporated aluminum on top of e-beam resist, before the e-beam exposure. For deposition onto the unexposed e-beam resist, you need to use the thermal source.
Recipe
Use process 9 in Wordentec to deposit thermal Aluminum.
Observe: you need to get a special training to use the thermal deposition source.
Set-up
- Two "boats" of Tantalum are mounted (on top of each other) in the thermal source each time.
- We have also earlier seen that two boats give stable depositions, since the lower boat gets hot (and heat the top boat), even if there if a thick layer of aluminum all over the top boat.
- If the last deposition from the source was Aluminum, the same boats can be used, otherwise they should be changed.
- "Small" Al pellets (diameter 1/8", height 1/8") are used. Use these small pellets to get a more uniform deposition with stable deposition rate.
- The boat should be placed as horizontal as possible, so the Aluminum metal will be evenly distributed in the boat after it is melted. If it is a problem to mount the boats horizontal, contact equipment responsible persons.
Program settings
- Deposition rate is normally 1 or 2 Å/s.
The settings saved in the material file for thermal aluminum are these:
- Soak power 1: 5%
- Soak power 2: 7%
These are already saved in the process.
Notes
This files contains some short notes regarding thermal Al evaporation: Short Tests thermal deposition of Al in Wordentec