• Zikry, Mohammed A.
• Shanthraj, Pratheek
• Rezvanian, Omid

Abstract

—Three-dimensional fractal representations of surface<br/>roughness are incorporated into a finite-element framework<br/>to obtain the electrothermomechanical behavior of ohmic<br/>contacts in radio frequency (RF) microelectromechanical systems<br/>(MEMS) switches. Fractal surfaces are generated from<br/>the Weierstrass–Mandelbrot function and are representatives of<br/>atomic force microscope surface roughness measurements of contact<br/>surfaces in fabricated RF MEMS switches with metal contacts.<br/>A specialized finite-element scheme is developed, which<br/>couples the thermomechanical asperity creep deformations with<br/>the electromechanical contact characteristics to obtain predictions<br/>of contact parameters and their evolution as a function of time<br/>and loading. A dislocation-density-based crystal plasticity framework<br/>is also used to investigate microstructure evolution at microcontacts<br/>and its effects on contact parameters. Using this<br/>approach, simulations are made to investigate how surface roughness,<br/>initial residual strains, and operating temperature can affect<br/>asperity contact behavior. Based on these predictions, tribological<br/>design guidelines can be obtained to increase the lifetime of<br/>low-contact-resistance RF MEMS switches by limiting stiction and<br/>electrical resistance increase.

Topics

• density
• impedance spectroscopy
• microstructure
• surface
• simulation
• dislocation
• plasticity
• Surface roughness measurement
• crystal plasticity
• creep