Dear Kevin,

We have found that TMAH etched (111) surfaces are smoother with increasing TMAH
concentration, although at the expense of both (111) and (100) etch rates.
Isopropyl alcohol also affects TMAH etch characteristics, but we have not
studied its effect on (111) surface smoothness. Merlos et.al. have reported
smoother TMAH etched surfaces with the addition of isopropyl alcohol. (TMAH/IPA
Anisotropic Etching Characteristics, Sensors and Actuators A, 37-38, pp.737,
1993).

We have also noticed a significant difference in (111) surface smoothness
between wafer batches. We suspect oxide is precipitating from oxygen rich
wafers during high temperature processing. Has anyone else had experience with
this problem?

Thanks, Rick
--
Dr. Rick Mlcak
ITM, Inc.
mlcak@itminc.com
301-577-1788