Two reactors (STS, Oxford Estrelas) are dedicated to the deep anisotropic etching of Si allowing to realize the Bosch switched process (step time up to 10 ms) and the cryogenic process (continuous etching in the mixture of SF6/O2 in the temperature range -70°C to -150°C). The resource carries out developments on the choice of masks (optical resin, e-beam resin, SiO2 or Si3N4) in collaboration with the lithography resource. The presence of electrostatic and mechanical clamps for 3'' and 4'' allow us to manage etchings on samples from a few mm (bonding) to 4″. SOI etchings can also benefit from an anti-notching device.

Deposits of organic thin films under vacuum are also proposed (parylene, pentacene,...).

- Variation of the etching profile, such as the angle of the etching flanks, by adjusting the oxygen content in the SF6/O2 mixture in cryogenic etching.


1.  Change of etching angle with the variation of oxygen rate in cryogenic process

- Deep anisotropic etchings with very low sidewall roughness by cryogenic process. Generally used for optoelectronic component realization as a replacement for Bosch etching for this reason.


- Bosch process for creating membranes, especially on SOI, with stress control, thin thicknesses, or even drilled membranes. Typically used for MEMs or BioMEMs applications.

gravure Bosch

3. Realization of a HF MEMs for AFM by Si Bosch etching (Team NAM6)

- Deep and very dense engravings by Bosch process, such as µ-pillars or µ-tubes. Engraving possible up to 100 µm depth on tube diameters of 2 µm-3 µm and pitch of 1 µm. Used in particular in energy storage applications.

Bosch process

4. etching of microtubes diameter 2µm, pitch 1µm in Bosch process (CSAM group, C. Lethien, RS2E)

Expertise and know-how: other

- Silicon substrate feedthrough in Bosch process

- Deposition of conformal C4F8 layers on any type of surface including nanowires. Use as surface functionalization to increase contact angle in microfluidic applications, bioMEMs,...