| AVS 55th International Symposium & Exhibition | |
| Tribology Focus Topic | Wednesday Sessions |
| Session TR+MN+NC-WeM |
| Session: | Surfaces and Interfaces in MEMS/NEMS |
| Presenter: | M. Walker, North Carolina State University |
| Authors: | M. Walker, North Carolina State University N. McGruer, Northeastern University J. Krim, North Carolina State University |
| Correspondent: | Click to Email |
Studies of RF MEMS switch performance under ultra clean and controlled environmental conditions have to date been extremely limited.1 Such studies are highly valuable however, as they provide an opportunity to separately examine the impact of various factors such as contamination films, creep, deformation and stiction that plague current RF MEMS switch reliability. We have constructed a custom ultra high vacuum chamber with in situ surface cleaning, variable temperature and gas dosing capabilities in an effort to isolate the multiple variables that impact RF MEMS contact resistance and longevity. This chamber allows us to study switches in atmosphere followed by studies performed in the cleanest environment possible. We have investigated cantilever MEMS devices with both Au on Au and Ru on Ru contacts. Au on Au switches have so far been investigated by the vast majority of studies, and provide baseline material for our studies. Ru on Ru switches are far less studied. Ru is currently our material of interest on account of its harder properties that resists creep and deformation. In atmosphere we observe the resistance of a closed switch over time then open the switch. We pump the chamber to a base pressure of 9 x 10-10 torr followed by measuring the resistance over time then opening the switch. Surface cleaning is performed via in situ oxygen plasma. This is followed by closing the switch and observing the resistance over time. We have observed switches that have initially had infinite resistance in both atmosphere and UHV exhibit tens of ohms contact resistance after oxygen plasma cleaning. The resistance values after oxygen cleaning are closer to the theoretical values for clean contact. We compare these resistance changes to theoretical models2 that account for creep and deformation of the switch contacts. A study of contact resistance as a function of hydrocarbon uptake is in progress.3 This work was supported by the DARPA Center for RF MEMS Reliability and Design Fundamentals Grant # HR0011-06-1-0051 and the AFOSR Extreme Friction MURI Grant #FA9550-04-0381.
1 C. Brown, A. Morris, A. Kingon, J. Krim, submitted to J. MEMS
2 O. Rezvanian, C. Brown, M. Zikry, A. Kingon, J. Krim, D. Irving, D. Brenner, submitted to J. Applied Physics
3 H. Koidl, W. Rieder, Q. Salzmann, vol. 22, No. 3, 1999 .