High Yield Precision Transfer and Assembly of GaN µLEDs Using Laser Assisted Micro Transfer Printing

Abstract

Rapid developments in GaN based µLED mass transfer & assembly have been driven by the demand for high resolution, bright and efficient displays for various solid-state lighting applications. There has however been a roadblock for the commercialization of this technology due to the poor transfer yields attained and high processing costs. The Laser Lift-Off (LLO) process used to release the µLEDs from their native substrate (sapphire) is non-trivial as it can easily crack the chips. In this work, we propose a new µLED transfer and assembly process based on adhesive bonding using a laser de-bondable thermoplastic polyimide (HD3007) that can potentially achieve transfer yields >99%. The LLO process is also done more reliably by using mechanically supported µLEDs which helps to attain nearly 100% LLO yield.