Specific Process Knowledge/Etch/DRIE-Pegasus/FAQ/Masks

Question 1

I remember you said that you don't like Al as masking material because it will get sputtered off (am I right?) - but what about ALD deposited aluminium oxide - it is, as far as I know, much harder and resistant than Al..?

Answer 1

We don't have experience with ALD deposited aluminium oxide as a mask, however for some ESC configurations we have seen evidence of sputtering of the alumina uniformity shield surrounding the wafer; this would lead me to believe that the ALD aluminium oxide could still sputter and cause contamination issues.