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Wet bench used generally for KOH-based etching processes :
1. Anisotropic etching of Silicon
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 :
http://www.lelandstanfordjunior.com/KOH.html
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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
2. Femto-second laser assisted wet etching (FLAE method) of Glass
The bench contains also an automatic ultrasonic wet etching station, being a part of FEMTOprint system for 3D micromachining of glass. The station is dedicated for releasing of 3D structures, exposured previously by f-s laser using f100 aHead Enhanced FEMTOprint machine, in hot KOH solution.
- Etch rate of exposured glass depends strongly on parameters of laser process (typ. ~2µm/min for Fused Silica with selectivity of >200).
- Compatiblity with chip-level and wafer-level (up to 6") etching (tank size LxWxH: 50x29x20cm3).
- Adjustable parameters of etching process: temperature, US power and frequency.
- Due to big capacity (28l of DI), heating up to the process temperature takes 2.5h (to be considered during reservation).