Dilute HF is much better than BHF. I was surprised to find this. 50:1 HF dip may be a little slow, but it is worth a try. I would also try mixing 1 conc, HF to 9 H2O. Or stronger still. What are you stopping on?
As always with wet etch, I recommend a hot plate re-bake, 4 or 5 min., 115 C within ~ 30 min of the wet etch. If you stop and rinse for inspection, re-bake again before going back to the etch. This helps a lot with resist lifting and undercut.
TiO2 should plasma etch in an Al recipe, P5000 for semi-clean or PQuest for "golden"
jim
From: Neil Dasgupta <dasgupta@stanford.edu>
To: labmembers <labmembers@snf.stanford.edu>
Sent: Tuesday, August 30, 2011 2:16 PM
Subject: wet etching TiO2
Hi all,
Does anybody have any experience wet etching TiO2 thin films? I tried 20:1 and 6:1 BOE today on TiO2 films ranging from 15-40 nm deposited by ALD with no luck. Oh and also we use PR as an etch mask, so it would be preferable if the etchant was at least somewhat selective against resist.
Any help is greatly appreciated.
Thanks,
Neil Dasgupta
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