Wet bench used for silicon etching :
We use a KOH solution with a mass concentration of 41% (10M)
Etching rate at 55°C : 0.25 µm/min (Si (100))
To know etching rate for different temperature, you can use this website :
Silicon 100 etches anisotropically, with a 54.74° angle from the plane. Masked silicon will etch as shown in the diagram.
source : http://cleanroom.byu.edu/KOH