we use Transene Chrome etchant which is ceric ammonium nitrate. several
photoresist masks were used successfully,

30nm: 25sec, slow agitation
50nm: 40sec, slow agitation
100nm: 80sec, slow agitation
200nm: 80sec, slow agitation
300nm: 90sec, slow agitation

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Salam R. Gabran, MASc.
Research associate, PhD. Candidate
Center for Integrated RF Engineering
(CIRFE Lab)
ECE Dept., University of Waterloo,