Hot-switched lifetime and damage characteristics of MEMS switch contacts

Abstract

Using a custom built contact testing system, direct current micro contact damage under hot-switching conditions was explored in ruthenium-on-ruthenium contacts operated at a contact force of approximately 400 μN. For the first time, contact damage on making and breaking contact under bias (leading and trailing edge hot switching) is compared. Trailing-edge hot switching leads to significantly higher adhesion (1.5-4 times higher) than leading-edge hot switching. The high-voltage tests (3.5 V) lead to polarity-dependent material transfer, with material moving in the direction of the electric field. The amount of material transfer does not depend strongly on the current limit from 0.78 to 380 mA. The low voltage (0.71 V) tests result in much less damage, and the material transfer does not have a clear directionality. However, the amount of damage does increase significantly as the current limit is increased from 16 to 78 mA. Also observed for the first time is a new type of high-current, short duration current spike associated with hot switching events at voltages above 1.5 V. The fact that these spikes occur at the higher voltage but not at the lower voltage suggests (but does not prove) that they are associated with the polarity dependent material transfer.

Reliability in Hot Switched Ruthenium on Ruthenium MEMS Contacts

“…A preliminary characterization of the observed material transfer and contact evolution of the switches was reported in previous work by the authors [7]. It was shown that while the adhesion between the contacts was different when hot switching voltage was applied to the leading edge as opposed to the trailing edge, the net transfer of contact material, or the overall damage to the contact, was comparable.…”

“…In this paper, the material transfer is studied in greater detail under varying hot switching conditions. While our earlier work [7] used a single approach and separation rate for the electrical contacts, the experiments in this work have been conducted at varying rates. Also, the effect of prolonged bipolar hot switching is studied and reported for the first time.…”

Development of a MEMS test platform for investigating the use of multi-walled CNT composites electric contacts

“…Electrostatically actuated MEMS based switches typically switch in the region of 50 µN to 1000 µN [7,15]. Further to this, the setup is comparable to that of a typical MEMS switch, with the primary difference being that one of the electrical contacts is an Au/MWCNT composite.…”

Extension of the Hot-Switching Reliability of RF-MEMS Switches Using a Series Contact Protection Technique

“…Several previous works have reported field induced material transfer damage mechanisms in hot-switching condition [19]- [21]. The common damage mechanisms include field evaporation, field emission, arc or pseudo-arc material transfer, and ohmic heating/bridge material transfer.…”