Hi Xiao,

It can be found from the following reference:

"Anisotropic etching of crystalline silicon in alkaline solutions", J.
Electrochem. Soc., Vol.137, No.11, p3612, Nov.1990.

10%KOH  13.3um/hour (50degreeC)    25.2(60)  46(70)  82(80)

Hope it helps.

Best regards,
Yours sincerely
Fei Wang
______________
Postdoctoral researcher, Dr
MIC - Department of Micro and Nanotechnology
Technical University of Denmark (DTU)
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Email: fei.wang@nanotech.dtu.dk
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