Ultra-Stretchable Interconnects for High-Density Stretchable Electronics

TL;DR

This paper presents CMOS-compatible, ultra-stretchable interconnects with micron-scale footprints, enabling high-density stretchable electronics through innovative 3D microfabrication techniques that achieve over 2000% elastic stretch.

Contribution

Introduction of a CMOS-enabled, free-standing, miniaturized interconnect structure leveraging 3D kinematic mechanisms for extreme stretchability in high-density electronics.

Findings

Elastic stretch beyond 2000% with <0.3% resistance change

Ultimate stretch beyond 3000% with <1% resistance change

Over 10 million cycles at 1000% stretch with stable resistance

Abstract

The exciting field of stretchable electronics (SE) promises numerous novel applications, particularly in-body and medical diagnostics devices. However, future advanced SE miniature devices will require high-density, extremely stretchable interconnects with micron-scale footprints, which calls for proven standardized (complementary metal-oxide semiconductor (CMOS)-type) process recipes using bulk integrated circuit (IC) microfabrication tools and fine-pitch photolithography patterning. Here, we address this combined challenge of microfabrication with extreme stretchability for high-density SE devices by introducing CMOS-enabled, free-standing, miniaturized interconnect structures that fully exploit their 3D kinematic freedom through an interplay of buckling, torsion, and bending to maximize stretchability. Integration with standard CMOS-type batch processing is assured by utilizing the Flex-to-Rigid (F2R) post-processing technology to make the back-end-of-line interconnect structures free-standing, thus enabling the routine microfabrication of highly-stretchable interconnects. The performance and reproducibility of these free-standing structures is promising: an elastic stretch beyond 2000% and ultimate (plastic) stretch beyond 3000%, with <0.3% resistance change, and >10 million cycles at 1000% stretch with <1% resistance change. This generic technology provides a new route to exciting highly-stretchable miniature devices.