I have a 400 nm carbon film deposited via chemical vapor deposition on a fused quartz substrate. I need to remove half of the film to expose the underlying quartz substrate. Any suggestions would be much appreciated.
Hi Megan,
In my experience, the most efficient way to remove carbon film would be to etch it in a high-density oxygen plasma using aluminium film as a mask. The high-density plasma is generated by ECR or ICP plasma sources with rather high radiation power (few hundreds Watts). Also, some small (10-20 Watts) of additional RF substrate bias will be needed to activate the etching process.
Unfortunately, this sort of plasma systems are not always available in a lab, so alternatively, you can try a good old ion milling with argon ions. This methods is more crude and can potentially cause defects in you substrate and/or film.
A regular capacitively coupled RF oxygen plasma has a very low etching rates for carbon films, and would take too long to remove all 400 nm of your film.
Good luck,
Andy
You can also remove some carbon films from silica surface by submersion in 47% hydrofluoric acid. That is a very nasty acid however, you want to make sure you understand the danger and have proper procedures and protective gear. Only allow the part you want removed to be dipped in the acid. I expect it to work in under 30 minutes if it will work at all on your particular carbon.
Hydrofluoric acid will do the job, but if you go too deep, it will also etch the fused quartz material. If you do it with sulfuric acid (also much less dangerous to use), it will attack the carbon layer without any risk for the fused quartz below (which is only sensitive to HF and to strong bases).
Thank you all for the great suggestions, they were very helpful! In the end, I decided to go with placing a 25 micron thick piece of Ni foil and an additional piece of quartz clamped on top of the foil over the carbon I wanted to protect. Then I did an O2 RIE to remove the carbon film. It worked, was really easy, and did not introduce additional contaminants. My project can now move forward!
If you access to laser micromachining system, you can remove a variety of patterns or machine the pattern designs you need very easily and very rapidly with high degree of resolution. Laser ablation will even remove partial film if the process is controlled effectively.
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