Add a small amount of ammonium persulfate. This technique was published
by Erno Klaussen at Stanford.

ÂÞÔª wrote:

> Dear Sirs:
>     We want to etch a V-groove with TMAH.But our experiments showed
> that the surface is very rough with many hilllocks. By add IPA or
> (NH4)2S2O3, the surface is still rough.And the concentration of the
> TMAH we used is 5%(wt)~22%(wt).
>     Would someone kindly to tell us how to have a V-groove without
> hilllocks by using TMAH?
>     Thanks a lot.
>
>     Best Regards!
>
>                        Yours Sincerely:LuoYuan
>                            Aug.8,2001
>
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