Influence of temperature on the actuation voltage of RF-MEMS switches

Most of the actual applications for RF-MEMS switch require high reliability, but consolidated qualification procedures are still lacking. This paper focuses, in particular, on the role of temperature on the switch reliability from a mechanical point of view, showing how this depends on the switch architecture and membrane material. Double clamped switches are sensitive to buckling, and this is the factor limiting their operational temperature, even though the range exploitable can be wide enough for many applications. Residual stress and thermal expansion coefficient of the mobile membrane are the most important parameters to understand and control this phenomenon. Cantilever switches are less influenced by the temperature in their performances, and have a much wider operational range. Other temperature-related factors are affecting the switch reliability in this case, such as elastic modulus variation, dielectric charging effects and creep.

► Variations of actuation voltage with temperature were measured for two switch typologies.
► For double clamped switches the limiting factor is the stress of the membrane.
► For cantilever switches other factors play a role.
► The operational temperature of cantilever switches is much wider than for double-clamped ones.