Effect of contact statistics on electrical contact resistance

Jang, Yong Hoon; Barber, J. R.

doi:10.1063/1.1622995

Cited by 39 publications

(31 citation statements)

References 11 publications

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“…Empirical relations have been established to connect the contact area and the thermal/electrical contact resistance [7]. A rigorous examination by Barber [8] proves the analogy between the conduction problem and the incremental elastic contact.…”

Section: Properties That Can Be Deduced From Rough Surface Contactmentioning

confidence: 99%

“…Scaling relations of the total contact area versus the applied load and roughness properties can be deduced [4], and compared with numerical simulations that have pre-specified spatial cutoff sizes [5,6]. We also discuss the validity conditions of predictions that are based on contact compliance, such as thermal/electrical contact resistance [7][8][9]. At microscale and nanoscale, it is worth noting that we still lack sufficient incorporation of micromechanics and novel deformation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Some Issues of Rough Surface Contact Plasticity at Micro- and Nano-Scales

2004

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Rough surface contact plasticity at microscale and nanoscale is of crucial importance in many new applications and technologies, such as nano-imprinting and nano-welding. This paper summarizes our recent progress in understanding contact plasticity from a multiscale point of view, and also presents our perspectives. We first discuss a contact model based on fractal roughness and continuum plasticity theory. Interestingly, our simple, elastic-plastic contact model of Weierstrass-Archard type gives rise to many practical scaling relations of contact pressure, contact compliance etc. The usefulness of those predictions is discussed for the experiments of indentation and measurements of thermal and electrical properties. A material length scale can be introduced by a nonlocal plasticity theory, or implicitly by dislocation mechanics model. The recent work on micro-plasticity of surface steps gives a variety of surface yielding and hardening behaviors, depending on interface adhesion, roughness features and slip systems. As a consequence, a rough surface contact at small scale can lead to the formation of a boundary layer with sub-layer dislocation structures, which cannot be predicted by existing strain gradient plasticity theories. The micromechanical analysis of surface plasticity could serve as the connection between microscale bulk dislocation plasticity and nanoscale atomistic simulations.

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Section: Properties That Can Be Deduced From Rough Surface Contactmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Some Issues of Rough Surface Contact Plasticity at Micro- and Nano-Scales

2004

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“…This raises the question of the possible physical origins of the factor of the approximate doubling in the resistance: A dielectric material (for dodecane, K = 2) confined within the contact is expected to raise the resistance by many orders of magnitude [6,31] and depend closely on the number of molecules confined within. It is possible that the molecules, being physisorbed and mobile, are not actually within the contacts but squeezed out into the regions immediately outside of them [46][47][48][49][50][51]. Indeed, Patton et al [3] reported that contact force of 200 lN is high enough to remove SAM molecules outside of MEMS contacts.…”

Section: Discussionmentioning

confidence: 94%

Electrical Contact Resistance and Device Lifetime Measurements of Au-RuO2-Based RF MEMS Exposed to Hydrocarbons in Vacuum and Nitrogen Environments

et al. 2011

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Electrical Contact Resistance (ECR) measurements are reported for RF micro-electromechanical switches with Au-RuO 2 contacts, situated within an ultrahigh vacuum system equipped with in situ oxygen plasma cleaning capabilities. Two studies are reported, each involving a comparison of the ECR in vacuum and nitrogen environments for measurements performed immediately after cleaning. The first study reports measurements of initial resistance (resistance measured upon first time closure) versus pressure as dodecane gas is admitted to the chamber. A significant increase is observed at pressures in vacuum as low as 10 -5 torr, (P/P sat \ 10 -4 ) consistent with earlier reports involving repetitive cycling of macroscopic switches in partial pressures of hydrocarbons in nitrogen. Somewhat unexpectedly, however, the resistance only doubles, even for pressures sufficiently high as to result in full monolayer condensation. In a second study, switch lifetimes in vacuum (10 -8 -10 -9 torr) and nitrogen gas environments are compared, for switches operated immediately afterward, or alternatively left open for a number of days before operation. Although it was expected that vacuum would reduce and/or prevent contamination of the electrical contact surfaces, no enhancement or extension of lifetime was observed: Continuous operation of a switch in a nitrogen environment immediately after plasma cleaning was in fact the only procedure observed to indefinitely prolong device lifetime. The results suggest that (1) Hydrocarbon reaction products, but not mobile physisorbed hydrocarbons themselves, are responsible for increasing ECR by orders of magnitude and (2) Repetitive cycling motion of a clean switch in nitrogen inhibits formation of physisorbed hydrocarbon contaminants on the contacts, while vacuum levels far superior to 10 -9 torr are required to prevent contamination.

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“…When load is increased, these plastically deformed spots join to form elastic spots [16]. The concept of fractal roughness has also been implemented to electrical [17] and thermal [18] contact resistances. Majumdar and Tien [18] developed a TCR model based on fractal characteristics of roughness and compared their model with experimental data.…”

Section: Why Plastic Microcontacts?mentioning

confidence: 99%