Specific Process Knowledge/Thin film deposition/Deposition of Tungsten
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Tungsten deposition
Tungsten (W) can be deposited by e-beam evaporation. It requires very high temperature to evaporate, so it is at the performance limit of the 6 kW power supplies of our systems. This means the deposition rate is limited. Additionally, the chamber (and substrate) will get hot during deposition despite water cooling, and this means the pressure rises during the deposition as the chamber is baked out. It is therefore not easy to deposit films much thicker than 50-60 nm. Talk to staff when you want to deposit W (write to thinfilm@danchip.dtu.dk). In the chart below you can compare the deposition equipment.
E-beam evaporation (Temescal) | E-beam evaporation (Physimeca) | |
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General description | E-beam evaporation of W | E-beam evaporation of W |
Pre-clean | Ar ion beam | None |
Layer thickness | 10Å to 600Å* | 10Å to 500Å* |
Deposition rate | 0.5 Å/s to 2 Å/s | about 1 Å/s |
Batch size |
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Allowed materials |
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Comments | Substrate gets hot during deposition
(for a 60 nm film it rose above 123 C) |
* For thicknesses above 20 nm talk to staff (write to thinfilm@danchip.dtu.dk), as the heat and subsequent pressure rise means the deposition needs to be carried out in steps.