I am trying to etch Polystyrene nano-sphere using Plasma etching process. For etching process pressure require is 5-10 mTorr as I have seen in some papers.
Is plasma etching process possible at lower pressure? If yes what other things I should keep in mind.
Please share some references as well. (If possible)
I think pressure of 5-10 mtorr is high for plasma etching purposes. However, it may be so for metallic surfaces. therefore, for nonmetallic surfaces it should be lower. At pressure of 1-3 mtorr, you can perform excellent plasma etching for polystyrene surface at current density of 2 mA/cm2 or lower for a couple of hours.
Hi
Actually 5-10 mTorr is already on the lower side of the plasma etching process, I have seen people generally using high pressure than this, now as you suggested why people uses 5-10 mTorr, the reason being that it gives steep wall(being mean free path is high), while at higher pressures it may give partially isotropic structure as the mean free path is low.
Now there is a trade off, if you are using low pressure
- Your plasma may not strike
- Etching rate can be very low
I have not particularly etched polystyrene beads but I think you might be getting an idea that why people are using low pressures.
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