Dear colleagues,

I am working on etching Si in KOH until 5 to 10um is left without
using P++ doping.But I have observed a 7um etching depth
difference between the OF side and it's opposite side. And an
almost 20um difference in the maximum and minimum etching depth
measured within the wafer.

I tried a bubbler within the etching bath but the resulting
etching distribution was almost the same as before.

I am wondering if there are other ways of obtaining a good KOH
etching distribution.Any idea and suggestions will be greatly
appreciated.

Regan Nayve
[email protected]

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Etching condition
KOH           : 15% 90C
Temp control  :  $B!^ (B1C
Etching bath  : Stainless(with top cover)
Bath dimension: L20 W23 H23  (cm)