Erratum: “A single asperity study of Au/Au electrical contacts” [J. Appl. Phys. <b>93</b>, 4661 (2003)]

Tringe, Joseph W.; Uhlman, T. A.; Oliver, A.; Houston, Jack E.

doi:10.1063/1.1641958

Cited by 13 publications

(14 citation statements)

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“…Although not explicitly pointed out, a previous study showed a decrease in R with increasing current [46]. To further support our hypothesis of creep at low current, we carefully monitored the temporal behavior of contact force.…”

Section: Contact Resistancementioning

confidence: 74%

“…For instance, it has been reported that there are 20-40 Å of adsorbed hydrocarbons on freshly cleaned Au [44,45]. These alien films reduce and/or prevent metallic contact and increase R, but may actually be beneficial by reducing adhesion [46]. Contact resistance of a few ohms is typical of surfaces contaminated with carbon [47][48][49].…”

Section: Electrode Materialsmentioning

confidence: 99%

“…Other typical contaminants in electrical contacts include particles, corrosion products, friction polymers, organic solvents, lubricants, and silica [50]. Contaminants are generally nonconducting and reports have shown that tunneling is the dominant charge transfer mechanism for Au contacts in both air and dry nitrogen environments [45,46,51,52].…”

Section: Electrode Materialsmentioning

confidence: 99%

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Fundamental studies of Au contacts in MEMS RF switches

2005

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Microelectromechanical systems (MEMS) radio frequency (RF) switches hold great promise in a myriad of commercial, aerospace, and military applications. However, there is little understanding of the factors determining the performance and reliability of these devices. Fundamental studies of hot-switched gold (Au) contacts were conducted using a micro/nanoadhesion apparatus as a switch simulator. Experiments were conducted in a well defined air environment under precisely controlled operating conditions. Fundamental properties were connected to performance with an emphasis on the effects of contact force and electric current on contact resistance (R), microadhesion, and reliability/durability. Electric current had the most profound effect on switch performance. Observations at low current (1-10 lA) include: (1) slightly higher R; (2) asperity creep; (3) high adhesion after rapid switching; (4) switch bouncing; and (5) reasonable durability. Conversely, observations at high current (1-10 mA) include: (1) slightly lower R; (2) melting; (3) no measurable adhesion; (4) less propensity for switch bouncing; (5) necking of contacts; and (6) poor reliability and durability due to switch shorting. Low current behavior was dominated by the propensity to form smooth surface contacts by hammering, which led to high van der Waals force. High current behavior was dominated by the formation of Au nanowires that bridge the contact during separation. Data suggest the presence of an adventitious film containing carbon and oxygen. Aging of the contacts in air was found to reduce adhesion.

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Section: Contact Resistancementioning

confidence: 74%

Section: Electrode Materialsmentioning

confidence: 99%

Section: Electrode Materialsmentioning

confidence: 99%

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Fundamental studies of Au contacts in MEMS RF switches

2005

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“…On the other hand, the effect due to contaminant films on resistance of metal contacts is known to be significant. 16,17 For instance, Holm 16 showed that the magnitude of resistance of contaminant films can be 2.3 times larger than the constriction resistance for Au-Au contact with a load of 1.15 g ͑ϳ11.3 mN͒ at room temperature. Our measurements were performed when these thin films were exposed to ambient laboratory conditions for 72 h or more.…”

Section: Resultsmentioning

confidence: 99%

Contact resistance study of noble metals and alloy films using a scanning probe microscope test station

Chen

Lee

Guo

et al. 2007

Journal of Applied Physics

108

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The proper selection of electrical contact materials is one of the critical steps in designing a metal contact microelectromechanical system ͑MEMS͒ switch. Ideally, the contact should have both very low contact resistance and high wear resistance. Unfortunately this combination cannot be easily achieved with the contact materials currently used in macroswitches because the available contact force in microswitches is generally insufficient ͑less than 1 mN͒ to break through nonconductive surface layers. As a step in the materials selection process, three noble metals, platinum ͑Pt͒, rhodium ͑Rh͒, ruthenium ͑Ru͒, and their alloys with gold ͑Au͒ were deposited as thin films on silicon ͑Si͒ substrates. The contact resistances of these materials and their evolution with cycling were measured using a specially developed scanning probe microscope test station. These results were then compared to measurements of material hardness and resistivity. The initial contact resistances of the noble metals alloyed with Au are roughly proportional to their resistivities. Measurements of contact resistance during cycling of different metal films were made under a contact force of 200-250 N in a room air environment. It was found that the contact resistance increases with cycling for alloy films with a low concentration of gold due to the buildup of contamination on the contact. However, for alloy films with a high gold content, the contact resistance increase due to contamination is insignificant up to 10 8 cycles. These observations suggest that Rh, Ru, and Pt and their gold alloys of low gold content are prone to contamination failure as contact materials in MEMS switches.

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“…It is widely recognized that parameters such as surface topography, electrical and mechanical surface properties, environmental conditions, insulating films, contact load, and voltage drop play key roles in the current flow at contacting surfaces. 8 Those insulating films are extremely persisting and, even after surface etching, sputter cleaning in ultrahigh vacuum, and applying mechanical stress at the contact interface, charge transport still occurs by tunneling through energy barriers imposed by the insulating films. However, in most of the applications thin insulating films reside in the surfaces due to corrosion, oxidation, or contamination, thus hindering the current flow.…”

Section: Introductionmentioning

confidence: 99%

Electrical performance of contaminated rough surfaces in contact

Kogut

2005

Journal of Applied Physics

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The inevitable presence of thin insulating films at the contact interface of electrical contacts has an adverse effect on their performances. An attempt is made to study the electrical performance of degraded electrical contacts where insulating films reside at the contact interface of conductive rough surfaces. The degradation mechanism is based on gradual growth of an insulating film and the characteristics of the insulating film are assumed to be known without considering details regarding the physical and chemical origins of the growth mechanisms. The present study relies on recently developed theories for electrical contact resistance of clean and fully contaminated rough surfaces, thus bridging the gap between these two extreme cases. For thick insulating films no current flow occurs across contaminated asperity contacts, whereas for thin insulating films tunneling currents are taken into account. A relationship is obtained between the degraded electrical contact resistance and the metallic conductance area. The effect of tunneling currents on the performance of partially contaminated surfaces is negligible due to the considerable current flow across the metallic asperity contacts. The electrical performance of fully contaminated surfaces is sensitive to the thickness and integrity of the insulating films and, therefore, can be exploited to study the durability of thin insulating films.

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Erratum: “A single asperity study of Au/Au electrical contacts” [J. Appl. Phys. 93, 4661 (2003)]

Cited by 13 publications

References 0 publications

Fundamental studies of Au contacts in MEMS RF switches

Fundamental studies of Au contacts in MEMS RF switches

Contact resistance study of noble metals and alloy films using a scanning probe microscope test station

Electrical performance of contaminated rough surfaces in contact

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