I'm trying to coat Al by vapor deposition on a ~3 micron PDMS layer with little success despite degassing the PDMS for over an hour before vaporization. I suspect surface treatment may be necessary but I'm not sure what can be nice. Please help.
Is the PDMS layer polymerized or is it a monomer-adsorbate layer? If the PDMS is polymerized, then you should be able to coat it with a metal - we did this in the past by sputtering gold and silver on PDMS. However the situation may be different for monomer thin films ...
We use different PVD systems to metalize/pattern polymers. so it works quite well with thermal/electron beam evaporation or sputtering. If you dont realy rely on PDMS then you might use a thin PET foil.
Hi Kennedy
You should be able to sputter, e-beam evaporate or thermally evaporate aluminum onto your PDMS. I am not sure if plasma treating is the way to go as plasma treatment eats away the organics, in your case the organic portion of PDMS.
Could you kindly elaborate on the problems you are facing while coating aluminum?
Hi,
We evaporate Al on almost anything, including PDMS and other polymers and elastomers and the films are quite good if the surface is clean. About your question, it is not clear if your PDMS film is polymerized or not because the degassing process you describe.
Thank you all. I appreciate your responses greatly. Well, the objective of my coating a thin film of aluminium on PDMS is to improve selectivity during RIE etching. So I'm trying to coat Al on a crosslinked PDMS film, followed by a positive photoresist. Although Al coating improved a little bit after plasma treatment, still the surface distribution of the Al film was quite uneven (as determined by SEM observation). I have also tried degassing for 2 hours before evaporation deposition in order to reduce the effect of gassing that I suppose might affect the results during deposition. But this only resulted in cracking of the PDMS film, with little improvement on Al surface coverage.
Anyway, from the responses, I suppose it is workable. All I need is to improve on my method or change my equipment. I'm afraid, but a vaccum evaporator is all I have to achieve the deposition.
Once again, thank you for your kind responses. Great references they have been.
Is your evapoator thermal resistive or ebeam? PDMS may hold a large static charge that could change deposition behavior. Try mixing your PDMS under an anti-static ion blower
The cracking is also likely due to thermal expansion of the pdms. Is the substrate holder you're using cooled? If not, especially with something like Al you PDMS could be heating up while having the Al evaporated onto it. Then it would cool and shrink as you remove it from the evaporator causing the films to buckle which looks like the "cracking" that you're describing. If you don't have a cooling stage for the evaporation then you may want to try gradual steps in the heating up of the Al for your evaporation.
Hope that helps!
Hi Kennedy
If the PDMS flexes after metallization, the thin metal cracks. Mounting the PDMS to something flat like a silicon wafer or microscope slide and avoiding flexing after metallization should avoid cracking.
- Badges
- Science topic
- Similar topics
- Filing