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

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) could 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 beams using a perfluorated SAM. Uniform 9 Angstrom thick monolayers were observed. A static contact angle of 117degrees up to 300degreesC was measured. Furthermore, a complete 1 mum thick (gap 0.5 mum) polysilicon RF MEMS capacitor with aluminium interconnects realized with this process demonstrated the CMOS compatibility.