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Carbon nanotube micro-contactors on ohmic substrates for on-chip microelectromechanical probing applications at wafer level

Tas, Mehmet O., Baker, Mark A., Musaramthota, Vishal, Uppal, Hasan, Masteghin, Mateus G., Bentz, Jedidiah, Boxshall, Keir and Stolojan, Vlad (2019) Carbon nanotube micro-contactors on ohmic substrates for on-chip microelectromechanical probing applications at wafer level Carbon, 150. pp. 117-127.

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Abstract

CNTs can have the ability to act as compliant small-scale springs or as shock resistance micro-contactors. This work investigates the performance of vertically-aligned CNTs (VA-CNTs) as micro-contactors in electromechanical testing applications for testing at wafer-level chip-scale-packaging (WLCSP) and wafer-level-packaging (WLP). Fabricated on ohmic substrates, 500-μm-tall CNT-metal composite contact structures are electromechanically characterized. The probe design and architecture are scalable, allowing for the assembly of thousands of probes in short manufacturing times, with easy pitch control. We discuss the effects of the metallization morphology and thickness on the compliance and electromechanical response of the metal-CNT composite contacts. Pd-metallized CNT contactors show up to 25 μm of compliance, with contact resistance as low as 460 mΩ (3.6 kΩ/μm) and network resistivity of 1.8 × 10−5 Ω cm, after 2500 touchdowns, with 50 μm of over-travel; they form reproducible and repeatable contacts, with less than 5% contact resistance degradation. Failure mechanisms are studied in-situ and after cyclic testing and show that, for top-cap-and-side metallized contacts, the CNT-metal shell provides stiffness to the probe structure in the elastic region, whilst reducing the contact resistance. The stable low resistance achieved, the high repeatability and endurance of the manufactured probes make CNT micro-contacts a viable candidate for WLP and WLCSP testing.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Electronic Engineering
Authors :
NameEmailORCID
Tas, Mehmet O.m.tas@surrey.ac.uk
Baker, Mark A.M.Baker@surrey.ac.uk
Musaramthota, Vishal
Uppal, Hasan
Masteghin, Mateus G.
Bentz, Jedidiah
Boxshall, Keir
Stolojan, VladV.Stolojan@surrey.ac.uk
Date : September 2019
Funders : Engineering and Physical Sciences Research Council (EPSRC)
DOI : 10.1016/j.carbon.2019.04.115
Copyright Disclaimer : © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords : Carbon nanotubes; Electromechanical micro-contacts; Pd and Au metallization of CNTs; CNT contact resistances; CNT micro-probes
Depositing User : Clive Harris
Date Deposited : 15 May 2019 15:25
Last Modified : 12 Dec 2019 14:45
URI: http://epubs.surrey.ac.uk/id/eprint/851840

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