All,

Thank you for the recent discussion on TMAH etching.
At the Berkeley Micro/NanoLab we perform both KOH and TMAH etching.

Based upon our researchers experience and described in the the following
report:

INHIBITION OF PYRAMID FORMATION IN THE ETCHING OF SI P[100] IN AQUEOUS
POTASSIUM HYDROXIDE-ISOPROPANOL
Author(s): CAMPBELL SA, COOPER K, DIXON L, EARWAKER R, PORT SN, SCHIFFRIN DJ
Source: JOURNAL OF MICROMECHANICS AND MICROENGINEERING
Volume: 5    Issue: 3    Pages: 209-218    Published: SEP 1995

we added an oxygen bubbler to our KOH etch bath and significantly improved
roughness and finish of etched surfaces.

Are there published reports and similar mechanisms proposed for improving
etch finish of TMAH etched surfaces by increasing dissolved oxygen content
in the TMAH etch bath ?

Thank you for any related information.
Bill Flounders
Berkeley Marvell NanoLab


Prem Pal wrote:
> Dear Andrea,
>
> Thanks for appreciating our work.
>
> In wet anisotropic etching, it is hard to to get whole wafer surface
completely free of hillocks. Even in the echants which provide smooth etched
surface finish, some hillocks are observed. This we have mentioned in our work
"Study of rounded concave and sharp edge convex corners undercutting in CMOS
compatible anisotropic etchants”, Journal of Micromechanics and
Microengineering, vol. 17, no.11, pp. 2299-2307, November 2007.
>
> In 25 wt% TMAH + 0.1 vol% Triton, the etched surface with 8-10 nm roughness
can be achieved easily if the etching is performed on cleaned wafer and in
cleaned solution as the wet etching characteristics are very sensitive
impurities..
>
> Best regards
> Prem
>
> On Sat, 09 Oct 2010 18:04:05 +0530  wrote
>
>> Hi Prem,
>>
>
>
> i've read your paper "Complex three-dimensional structures in Si{1 0 0}
> using wet bulk micromachining", really a nice job!
>
> Just a question: which is the surface quality of (100) sufaces etched in
> TMAH+Triton ? Is it possibile to achieve a (100) mirro-like surface ?
>
> Best regards,
>
> Andrea
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