Specific Process Knowledge/Thermal Process/Furnace: Multipurpose annealing
From February 2024: RESIST PYROLYSIS FURNACE
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The Resist Pyrolysis furnace
The Resist Pyrolysis furnace it made by ATV Technologie, and it was installed in the cleanroom in November 2014.
In November 2024 the furnace was repaired by ATV Technologie. At the repair, the whole furnace body was changed, and all heaters were replaced. Also, the process exhaust flow was decreased by changing a valve in the exhaust line.
Until February 2024, the furnace was named "Multipurpose Anneal furnace", and then it became the "Resist Pyrolysis furnace".
The Resist Pyrolysis furnace is a research tool. It means, that it is mainly available for users working on certain research projects, especially in the Biomaterial Microsystems Group at DTU Nanolab.
The furnace is mainly being used for resist pyrolysis. It can also be used for annealing in nitrogen (N2) and oxidation with oxygen (O2), but O2 is mostly used for cleaning of the furnace after resist pyrolysis processes.
Process steps can run either at atmospheric pressure or in vacuum. A small N2 or O2 flow (up to 2 slm) can be applied in vacuum steps.
The quartz parts in the furnace (the furnace tube, the door sealing and the wafer boat) can be changed, depending on what processes and samples the furnace is used for, but it has been decided that a quartz set for resist resist pyrolysis will be mounted in the furnace all the time. This limits the number of materials that are allowed in the furnace.
Please note that all new resist and other materials have to be approved by the Thin Film group (thinfilm@nanolab.dtu.dk) before they are allowed in the furnace.
All process gases (except purge nitrogen) are heated, before they are introduced into the furnace at the door side.
The furnace tube is heated by use of 12 long heaters situated along the furnace tube and combined in three groups (top, bottom left and bottom right) and two flat heaters situated in the ends of the furnace tube. The this way the temperature will be very uniform everywhere in the furnace tube. The heating can be done very fast, up to 30 oC/min. The maximum allowed process temperature is normally 1050 oC, however up to 1100 oC without vacuum is possible. The maximum allowed process time at 1050 oC is 3 hours.
The furnace body surrounding the furnace tube consists of a top and bottom half-shell. To cool down the furnace (when the temperature is below 800 oC), the top half shelf can be lifted up, and cooling fans will then flow air from the surroundings around the furnace tube to cool it down. However, for safety reasons, the cooling fans will not the activated when there is hydrogen in the furnace, and cooling will then be very slow.
It is not possible to open the furnace when the temperature is above 300 oC.
For resist pyrolysis, samples with different resist layers are heated up to maximum 1050 oC in a nitrogen atmosphere. At high temperatures carbon is formed by pyrolysis of the resist. In this way conductive structures can be made from a resist patterned sample. If oxygen from the air or from outgassing of the resist is present in the furnace, the resist layer will be removed, thus it is important to evacuate the furnace and flush it with nitrogen, before a high temperature for resist pyrolysis is obtained. Pyrolysis of a large amount of resist may also be a problem due to resist outgassing.
The user manual, technical information and contact information can be found in LabManager:
Furnace: Multipurpose annealing
Process information
- Oxidation: look at the Oxidation page
- Annealing: look at the Annealing page
- Results from the Multipurpose Anneal Furnace acceptance test
- Pyrolysis
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