Temperature dependence of asperity contact and contact resistance in gold RF MEMS switches

Experimental measurements and modeling predictions were obtained to characterize the electro-mechanical response of two different gold contact radio frequency microelectromechanical system (RF MEMS) switches due to variations in the temperature and applied contact voltage. A three-dimensional surface roughness profile from AFM measurements of the top contact surface of a sample RF MEMS switch was used to obtain modeling predictions of the time-dependent deformation of the asperity microcontacts, real areas of contact, number of asperity microcontacts and constriction resistance. The experimental data indicated a decrease in the overall resistance and a decrease in the creep mechanism at 77 K and 5.6 K when compared to measurements at 293 K. At 293 K, there is more contact area per unit time, and the resistance drop from the increase in real contact area dominates the resistance increase due to asperity heating. At 77 K, the creep rate is reduced, and fewer asperities are in contact. At 5.6 K, the change in contact area over time is small, and the contact resistance measurement is dominated by the Joule heating. The data presented and constriction resistance modeling for gold RF MEMS switches show that temperature plays a significant role in the creep deformation and heating of switch contacts. (Some figures in this article are in colour only in the electronic version)