> Does anyone know how to etch nitride faster than is possible by hot
> phosphoric acid?  I am looking for etch rates of 50 - 100 A/sec.

I've measured the following etch rates:

                        Stoichiometric          Si-Rich
                        LPCVD Si3N4             LPCVD nitride

Concentrated HF (49%)   140 A/min               52 A/min
10:1 HF                 11                      3
25:1 HF                 6                       1
5:1 BHF                 9                       4

Note that it's difficult to mask strong HF mixtures (stronger than 3:1 or
so)
with photoresist because it tends to lift off.
Oxide is, of course, not an option as a mask with HF.

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Kirt R. Williams, Ph.D.
Research Staff Scientist
Lucas NovaSensor
1055 Mission Ct., Fremont, CA  94539-8203
[email protected]
(510) 661-6147  FAX (510) 770-0645
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