Research departments

Wet etching bench (KOH BHF)


Wet etching bench (KOH / BHF)
Paillasse d'usinage humide (KOH + BHF) (CTMN)


Contact :

Laurent ROBERT
TEMIS Sciences building – Office N1-21
03 81 66 66 47 (Office)
laurent.robert@femto-st.fr

Location :

TEMIS cleanroom
Chemistry Area



Principle :

This chemical bench enables to etch silicon, quartz, SiO2. The anisotropic silicon etching is based on the fact that, for some chemical solutions, the etching velocities are different according to crystallographic directions. For our etching, we use a solution of potassium hydroxide diluted in water (KOH). For quartz and SiO2, the solution used is buffered hydrofluoric acid (BHF).

Technical specifications :

Silicon wet etching :

- Solution used : Potassium hydroxyde KOH, H2O
- Concentration : 41 % in mass (10 moles / litre)
- Temperature : 55°C (85°C max)
- Stirring : 300 tr/mn
- Etching rate : 0.25 µm/min (at 55 °C, for Si (100))

SiO2 etching :

- Solution used : Buffered Hydrofluoric Acid (BHF)
- Concentration : 1 volume HF 50% for 10 volumes NH4F 40% in H2O
- Temperature : ambient
- Strirring : manual
- Etching rate : 50 nm/min

Quartz etching :

- Solution used : Ammonium bifluorure
- Concentration : 1 volume HF 50% for 1 volume NH4F 40% in H2O
- Temperature : 80°C max
- Stirring : magnetic
- Etching rate : some microns/min

Achieved results :

Microaccéléromètre

Si Tri-axis Micro-acceleromer

Réseau µ-pyramides_Gravure KOH

Si Micro-pyramids grating