Hi Pradeep,

FeCl3 will not attack any resist I've worked with.
Use high concentration FeCl3 solution.
Use high mass transport to achieve low undercut (like chemical milling).

Regards,
Dave

David Roberts (Wafer Plating Specialist)
Prodigy Surface Tech (408) 469-3203 cell
807 Aldo Ave., Suite 103
Santa Clara, CA 95054
Phone (408) 492-9390
FAX (408) 492-9391

-----Original Message-----
From: Pradeep Dixit [mailto:pradeep.ntu@gmail.com]
Sent: Wednesday, September 02, 2009 6:15 AM
To: General MEMS discussion
Subject: [mems-talk] Nickel wet etchants and selectivity with AZ9235 resist

Hello All,

I would like to seek advice from you.

I would like to etch 300 nm thick Nickel pattern without significant
undercut using 1:1:1 mixture of HNO3: H3PO4: DI water. Mask would be a
resist mask 2-3 µm AZ9235.

Does any one has idea about the selectivity of sputtered nickel with AZ9235
photoresist with this etchant?

I learnt that nickel can also be etched by Piranha solution (4:1 mixture of
H2SO4:H2O2) or by 30%FeCl3, or by Alumnium etchant etc. Has any body tried
it and can share the results and what masks .

Any suggest would be welcome

Thanks,
Pradeep