What Cr etchant are you using?

Don Friedrich
JDSU - Advanced Optical Technologies
Santa Rosa CA
Don.friedrich@jdsu.com

-----Original Message-----
From: Taekyung Kim [mailto:tkkim74@gmail.com]
Sent: Tuesday, February 24, 2009 9:28 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Cr etching after HF vapor or BOE treatment.

Hi folks,

I have a problem with Cr etching after HF vapor or BOE treatment.

30 nm of Cr blanket layer is deposited on 100 nm thermal oxide. Then, 40
nm
thick Pt electrodes are defined by electron beam lithography.
After another EBL, a window is defined around one of the electrodes. In
the
open window (6um x 10um), 300 nm width Pt electrode on top of Cr
(30nm)/SiO2
(100nm) is exposed.
Cr etchant (~200 nm/min) removes Cr layer and SiO2/Si layer is etched in
CF4/SF6 RIE. Now Pt/Cr/SiO2 beam is suspended. I was able to remove SiO2
layer with HF vapor or BOE. But the problem is that Cr layer is exposed
to
HF vapor or BOE, it is not easily etched in Cr etchant. It took several
minute and all the Pt electrodes were peeled off. Can Cr layer be
changed
during CF4/SF6 RIE process or during HF treatment?


Thanks

TK