Message: 4
Date: Mon, 05 Jan 2004 13:02:58 -0500
From: Robert D White 
Subject: [mems-talk] Necessity of HCl dip after PZT etch
To: mems-talk@memsnet.org
Message-ID: <200401051802.i05I2wa6010293@rise.engin.umich.edu>

MEMS community,

I am starting to work with PZT thin films (solgel and pulsed laser
deposited), which I plan to etch using diluted (10:1) BOE solution.
It was recommended to me by one source that after etching the PZT I
should perform a brief (5 min) dip in heated (50C) concentrated
HCl to removed metal fluorides created during the PZT etching.

Can anyone with experience working with PZT thin films comment on the
necessity and utility of the HCl dip?  Is this something that you have
done?  What are the effects of this step?

Many thanks,

Robert White
University of Michigan, Ann Arbor
rdwhite@umich.edu



Hi, Robert
I have had experience with piezoresponse imaging on PZT films on
different stages of photolithographic processes. This ferroelectric
domain imaging technique is very sensitive to surface contamination; 1
nanometer contamination layer kills signal completely. What I have found
that coercive bias before photolithography was ~ 5 V to switch domain
locally; after lift-off it was ~30 V because of contamination build-up.
HCL etching worked perfectly to regain surface quality. The caveat is
that the etch is very non-uniform with preferential etching at grain
boundaries, etc, so timing strongly depends on film quality.
Hope this helps
Sergei

--
Sergei V. Kalinin,
Oak Ridge National Laboratory,
1 Bethel Valley Rd,
Bldg. 3025, MS6030,
Oak Ridge, TN 37831
Phone: (865) 241-0236
FAX: (865) 574-4143
URL: sergei2.kalininweb.com