Specific Process Knowledge/Thin film deposition/thermalevaporator

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Thermal evaporator- A system for deposition of metals

Positioned in cleanroom A-1.

The main purpose of the thermal evaporator is to deposit Al for removing charging of the resist when doing EBL on isolating substrate.

It is not only usable for Al deposition. The thermal evaporator has room for two evaporation sources and thereby the possibility to make thin films of two different metals. At the moment not that many metals have been tested, so right now only Al and Ag can be evaporated. Cr can also be evapoarated (with very good results), but require a major change in hardware configuration. We have attempted to evaporate Au and Zn but these are not standard processes. If you would like to deposit these or other metals, please talk to the Thin Film group.

Compared to the Wordentec, the thermal evaporator is quicker to use if you only need to deposit on one wafer or on small samples, as it only takes about 15 minutes to pump down the chamber. You can also deposit thicker layers because the throw distance from source to sample is shorter, so the material use is more efficient: In the thermal evaporator, you get up to 200 nm per metal pellet, whereas in the Wordentec you get about 15 nm per pellet. However, the thickness uniformity is better for large samples in the Wordentec also because of the longer distance from source to sample.

So if you want a quick deposition process and/or a relatively thick metal layer, and your samples are small or the thickness uniformity is not critical, then the Thermal Evaporator is a very good choice for you. If you need to deposit on many wafers or you need a more constant layer uniformity across a full 4" or 6" wafer, then the Wordentec is best.


The user manual, APV, technical information and contact information can be found in LabManager:

Thermal Evaporator in LabManager


Process information

Materials evaporated in the Lesker Thermal Evaporator

We can also evaporate gold in this evaporator and can develop processes for other materials if requested.

Equipment performance and process related parameters

Purpose Deposition of metals
  • Thermal evaporation of metals
Performance Film thickness
  • 10Å - 1µm (Al and Ag)
  • up to 80 nm (Cr)
Deposition rate
  • 0.5-2 Å/s (Al), 5 Å/s (Ag), 1 Å/s (Cr)
  • In general, 0.5-10 Å/s is possible
  • We need to develop a new process for each rate
Thickness uniformity
  • approx. 13 % variation on a 4" wafer with 100 nm Al *
  • approx. 23 % variation on a 4" wafer with 100 nm Ag *
  • approx. 10 % variation on a 6" wafer with 100 nm Cr *
Pumpdown time
  • about 15 min
Process parameter range Process Temperature
  • Approximately room temperature
Process pressure
  • Below 4*10-6 mbar
Substrates Batch size
  • Up to 8" wafer
  • Or several smaller pieces
  • Deposition on one side of the substrate
Substrate material allowed
  • Silicon wafers
  • Quartz wafers
  • Pyrex wafers
Material allowed on the substrate
  • Silicon oxide
  • Silicon (oxy)nitride
  • Photoresist
  • PMMA
  • Mylar
  • Metals

* The variation is defined as (Max-Min)/Average for the various points measured on the wafer. The max. point was around the center and the min. somewhere along the edge. The exact location of the maximum thickness depends how the sample is placed relative to the point of maximum material flux. Measurement by Rebecca Ettlinger, Nov. 2018.