Leading and trailing edge hot switching damage in a metal contact RF MEMS switch

Basu, Anirban; Hennessy, R. P.; Adams, George G.; McGruer, N.E.

doi:10.1109/transducers.2013.6626816

Cited by 8 publications

(2 citation statements)

References 9 publications

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“…The hot switching voltage that was applied across the contacts was 5 V. The currents were attributed to Fowler Nordheim tunneling. Similar currents were observed independently in the present work using a transimpedance amplifier (for higher bandwidth measurements) as well as a source-measure unit as reported in [36,37]. It was observed that, even at a hot switching voltage of 1 V (less than the work function of Ru), a pre-contact current was present, indicating that Fowler Nordheim tunneling alone is not responsible for this current.…”

Section: Observation and Investigation Of Pre-contact Current -supporting

confidence: 89%

Hot switching damage mechanisms in MEMS contacts—evidence and understanding

Basu¹,

Hennessy²,

Adams³

et al. 2014

J. Micromech. Microeng.

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Using an AFM-based test setup, experiments were performed on Ru microcontacts under a variety of leading and trailing edge hot switching conditions, including different voltages, different currents, different polarities (including bipolar and ac up to 20 MHz), and different approach and separation rates. It was found that hot switching damage is a complex phenomenon for microcontacts. It consists of a number of different mechanisms occurring simultaneously to different degrees depending on the hot switching conditions. It was determined through a combination of experiments and models that the mechanisms leading to contact erosion operate when the electrodes are separated by less than a few Å or are barely touching. For leading edge hot switching, i.e. hot switching when the contacts are closing, the main damage mechanism was found to be associated with currents less than 0.15 mA. Pre-contact currents were observed on uncleaned contacts and were not found to contribute to contact damage. Despite the damage caused by hot switching, it was found that unless the contact material is almost or completely eroded, hot switching does not lead to high contact resistance or high adhesion on Ru contacts. Under bipolar hot switching conditions, microcontacts with a 400 μN contact force maintained a contact resistance of less than 1 Ω and a pull-off force less than 60 μN for more than 100 million cycles.

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Section: Observation and Investigation Of Pre-contact Current -supporting

confidence: 89%

Hot switching damage mechanisms in MEMS contacts—evidence and understanding

Basu¹,

Hennessy²,

Adams³

et al. 2014

J. Micromech. Microeng.

Self Cite

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show abstract

“…The mechanism of field evaporation from AFM/STM tips was originally described in [108], and essentially states that at small separations, atoms can tunnel from one surface to another at a threshold electric field 50% lower than that required for field evaporation at large separations. In [92], Yang et al suggest field evaporation to be a possible mechanism in the material transfer they observed, while the authors of this work have discussed this is extensively as well [4,109].…”

Section: Materials Transfer Mechanisms and Hot Switchingmentioning

confidence: 75%

A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

Basu

Adams

McGruer

2016

J. Micromech. Microeng.

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Direct contact, ohmic MEMS switches for RF applications have several advantages over other conventional switching devices. Advantages include lower insertion loss, higher isolation, and better switching figure-of-merit (cut-off frequency). The most important aspect of a direct-contact RF MEMS switch is the metal microcontact which can dictate the lifetime and reliability of the switch. Therefore, an understanding of contact reliability is essential for developing robust MEMS switches. This paper discusses and reviews the most important work done over the past couple of decades toward understanding ohmic micro-contacts. We initially discuss the contact mechanics and multi-physics models for studying Hertzian and multi-asperity contacts. We follow this with a discussion on models and experiments for studying adhesion. We then discuss experimental setups and the development of contact test stations by various groups for accelerated testing of microcontacts, as well as for analysis of contact reliability issues. Subsequently, we analyze a number of material transfer mechanisms in microcontacts under hot and cold switching conditions. We finally review the material properties that can help determine the selection of contact materials. A trade-off between contact resistance and high reliability is almost always necessary during selection of contact material; this paper discusses how the choice of materials can help address such trade-offs.

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Design and modeling of RF MEMS metal contact switch for wireless applications

Raman

Shanmuganantham

2016

2016 International Conference on Control, Instrumentation, Communication and Computational Technologies (ICCICCT)

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Leading and trailing edge hot switching damage in a metal contact RF MEMS switch

Cited by 8 publications

References 9 publications

Hot switching damage mechanisms in MEMS contacts—evidence and understanding

Hot switching damage mechanisms in MEMS contacts—evidence and understanding

A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

Design and modeling of RF MEMS metal contact switch for wireless applications

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