A flexible and stackable 3D interconnect system using growth-engineered carbon nanotube scaffolds
Journal article, 2017

One of the critical challenges for realizing flexible electronic systems for a wide range of applications is the development of materials for flexible and stackable interconnects. We propose and demonstrate a three-dimensional (3D)interconnect structure embedded in a polymeric substrate using metal-coated carbon nanotube (CNT)scaffolds. By using two different underlayer materials for the catalyst, onestep synthesis of a dual-height CNT interconnect scaffold was realized. The CNT scaffolds serve as flexible cores for both annular metal through-substrate-vias and for horizontal metal interconnect. The 3D-CNT network was fabricated on a silicon substrate, and once the scaffolds were covered by metal, they were embedded in a polymer serving as a flexible substrate after peel-off from the silicon substrate. The 3D-CNT interconnect network was exposed to mechanical bending and stretching tests while monitoring its electrical properties. Even after 300 cycles no significant increase of resistances was found. Electrically there is a trade-off between flexibility and conductivity due to the surface roughness of the scaffold. However, this is to some extent alleviated by the metalized sidewalls giving the horizontal wires a cross-sectional area larger than indicated by their footprint. For gold wires 200 nm thick, measurements indicated a resistivity of 18 μΩ.cm, a value less than one order of magnitude larger than that of bulk gold, and a value that is expected to improve as technology improves. The mechanical properties of the metalized scaffolds were simulated using a finite element model. The potential scale-up capability of the proposed 3D-CNT network was demonstrated by the stacking of two such polymer-embedded interconnect systems.

flexible electronics

carbon nanotubes

interconnect

3D integration

Author

Di Jiang

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Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Shuangxi Sun

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Michael Edwards

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

IDEX Biometrics UK Ltd

Kjell Jeppson

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Nan Wang

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Yifeng Fu

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Johan Liu

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Flexible and Printed Electronics

2058-8585 (ISSN)

Vol. 2 2 025003

Areas of Advance

Production

Subject Categories

Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1088/2058-8585/aa6a82

More information

Latest update

5/30/2018