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The stability and lifetime of electrical contact pose a major challenge to the performance of micro-electro-mechanical systems (MEMS), such as MEMS switches. The microscopic failure mechanism of electrical contact still remains largely unclear. Here conductive atomic force microscopy with hot switching mode was adopted to simulate the asperity-level contact condition in a MEMS switch. Strong variation and fluctuation of current and adhesion force were observed during 10,000 repetitive cycles, exhibiting an "intermittent failure" characteristic. This fluctuation of electrical contact properties was attributed to insulative carbonaceous contaminants repetitively formed and removed at the contact spot, corresponding to degradation and reestablishment of electrical contact. When contaminant film was formed, the contact interface became "metal/carbonaceous adsorbates/metal" instead of direct metal/metal contact, leading to degradation of the electrical contact state. Furthermore, a system of iridium/graphene on ruthenium (Ir/GrRu) was proposed to avoid direct metal/metal contact, which stabilized the current fluctuation and decreased interfacial adhesion significantly. The existence of graphene enabled less adsorption of carbonaceous contaminants in ambient air and enhanced mechanical protection against the repetitive hot switching actions. This work opens an avenue for design and fabrication of microscale electrical contact system, especially by utilizing two-dimensional materials.


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Intermittent failure mechanism and stabilization of microscale electrical contact

Show Author's information Tianbao MA1,( )Zhiwei YU1,2,Aisheng SONG1Jiahao ZHAO3,4,5Haibo ZHANG6Hongliang LU7,8Dandan HAN3,4,5Xueyan WANG7,8Wenzhong WANG6
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Inspur Beijing Electronic Information Industry Co., Ltd., Beijing 100085, China
Department of Precision Instrument, Tsinghua University, Beijing 100084, China
Innovation Center for Future Chips, Beijing 100084, China
State Key Laboratory of Precision Measurement Technology and Instruments, Beijing 100084, China
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

† Tianbao MA and Zhiwei YU contributed equally to this work.

Abstract

The stability and lifetime of electrical contact pose a major challenge to the performance of micro-electro-mechanical systems (MEMS), such as MEMS switches. The microscopic failure mechanism of electrical contact still remains largely unclear. Here conductive atomic force microscopy with hot switching mode was adopted to simulate the asperity-level contact condition in a MEMS switch. Strong variation and fluctuation of current and adhesion force were observed during 10,000 repetitive cycles, exhibiting an "intermittent failure" characteristic. This fluctuation of electrical contact properties was attributed to insulative carbonaceous contaminants repetitively formed and removed at the contact spot, corresponding to degradation and reestablishment of electrical contact. When contaminant film was formed, the contact interface became "metal/carbonaceous adsorbates/metal" instead of direct metal/metal contact, leading to degradation of the electrical contact state. Furthermore, a system of iridium/graphene on ruthenium (Ir/GrRu) was proposed to avoid direct metal/metal contact, which stabilized the current fluctuation and decreased interfacial adhesion significantly. The existence of graphene enabled less adsorption of carbonaceous contaminants in ambient air and enhanced mechanical protection against the repetitive hot switching actions. This work opens an avenue for design and fabrication of microscale electrical contact system, especially by utilizing two-dimensional materials.

Keywords: graphene, atomic force microscopy, microscale electrical contact

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Publication history

Received: 10 February 2022
Revised: 21 February 2022
Accepted: 28 February 2022
Published: 16 March 2022
Issue date: April 2023

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© The author(s) 2022.

Acknowledgements

The authors would like to acknowledge the support of the National Natural Science Foundation of China (Grant Nos. 11890671, 61774096, and 51935006), National Science and Technology Major Project (2017-VII-0013-0110), and the Fundamental Research Funds for the Central Universities.

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