Dear Mr.Ley,

I think that you would have tried to etch your wafers
at room temperature. If that is the case, then 10µm
per hour etchrate is normal. I would like you to do
the etching at 80°c and you may get a etch rate of 60
to 70µm per hour. If this is not the case, I am not
sure abt the solution to your problem.

Good luck

regards,
Venkat
Microsystems Department
Hamburg University of Technology, Germany.
www.tuhh.de/mst



Hi.
>
> I am trying to etch 100um deep V-pits in on 1-0-0 Si
> wafers.
> I am etching n-type (phosphorous doped) wafers of
> resistivity
> 7.5 - 12.5 ohm-cm.  I'm using a 10-weight % aqueous
> solution of
> KOH (i.e. 50g KOH pellets + 450 mL D.I. water) , and
> a ~1um-thick
> thermal oxide as an etch mask.  The etch pits are
> defined by 120
> um square holes in the oxide.  I am getting an etch
> rate of only
>  ~10 um/ hr for <100> Si.   From the literature I
> have read (Seidel,
> et al.  J. Electrochem. Soc. V. 137, No.11, Nov
> 1990), I expected an etch rate of ~80 um/hr.  I am
> getting an etch rate for the oxide
> that is close to what I expected (800-900
> Angstrom/hr).   Can
> anybody suggest to me what I'm doing wrong?   Any
> suggestion will
> be greatly appreciated.
>
> Thanks,
>
> Jed Ley
> Colorado School of Mines
> Golden, Colorado
>
>


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