A fluoro-ethoxysilane-based stiction-free release process for submicron gap MEMS

Parvais, Bertrand [UCL] Pallandre, Antoine [UCL] Jonas, Alain M. [UCL] Raskin, Jean-Pierre [UCL]

Nowadays, stiction remains one of the biggest reliability problems in the fabrication of micro-electromechanical systems (MEMS), especially when a small gap is used. To avoid the adhesion, a Self-Assembled Monolayer (SAM) can be coated. Main research in that field focuses on aliphatic chloro-silanes. We developed a novel wet-release CMOS compatible process for the fabrication of surface-micromachined beam using a perfluorated SAM. Uniform 9 Å thick monolayers were observed. A static contact angle of 121° was measured. Furthermore, a complete 1 µm thick (gap 0.5 µm) polysilicon RF MEMS capacitor with aluminium interconnects realized with this process demonstrated the CMOS compatibility.