Hello all,

I observed some residues after etching poly-Si with SF6. Mask was photoresist
and etch stop was Si3N4.

A thin veil is visible at the edges of the poly lines after ashing the
photoresist mask in O2 plasma. The veil extends out by the amount of resist
undercutting that occured during the poly etch. Is polymer formation typical
with SF6?

I tried several post-etch cleans to remove the residues without success: HF,
SC1, Nanostrip, and Pirhanna. I don't have any experience with the many post-
etch residue removers available. Has anyone had good success with a specific
product? What about a modified plasma resist strip sequence that uses a step
with O2 + low%CF4?

Thanks