microfab Service GmbH

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SURFACE TREATMENT

Self Assembling Monolayers SAM

Surface stiction is a major problem during fabrication of MEMS components, such as silicon sensors, microactuators or microfludic devices. In addition, the same phenomena are a limiting factor for reliability and lifetime of these components on the customer’s side.

The gas-phase SAM (self-assembling monolayers) coating process for micro components reduces or eliminates adhesion related phenomena. Essential for the industrial use of hydrophobic SAM-based coatings is the existence of a process suitable to be integrated in an industrial environment for fabrication of large volumes (serial production). microFAB has developed such a process together with international partner companies (Europlasma, Sonion A/S) and institutes (IMSAS Bremen, MIC/DTU Lyngby) in the scope of the European funded CRAFT project called HydroSurf.

Benefits of SAM coating

  • Avoidance of sticking during use of MEMS devices with delicate structures, like suspended membranes, movable comb structures or cantilevers
  • Avoidance of sticking during wet processing of wafers with suspended MEMS structures
  • Generation of a hydrophobic surface displaying low surface energy and high contact angles > 110°, similar to Teflon
  • Stabilization of the treated MEMS surface by low-temperature steps (full back-end process compatibility)
  • Excellent mechanical and thermal stability (up to 400°C, therefore compatible to standard-packaging-processes including solder reflow)
  • Selective coating of hydrophilic surfaces with OH-bonds only (metal pads are not coated)
  • Serial production compatible high-throughput, low-cost batch process