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.

• 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.