Laser-Driven Micro Transfer Placement of Prefabricated Microstructures

Microassembly of prefabricated structures and devices is emerging as key process technology for realizing heterogeneous integration and high-performance flexible and stretchable electronics. Here, we report on a laser-driven micro transfer placement process that exploits, instead of ablation, the mismatch in thermomechanical response at the interface of a transferable microstructure and a transfer tool to a laser pulse to drive the release of the microstructure from the transfer tool and its travel to a receiving substrate. The resulting facile pick-and-place process is demonstrated with the assembling of 3-D microstructures and the placement of GaN light-emitting diodes onto silicon and glass substrates. High-speed photography is used to provide experimental evidence of thermomechanically driven release. Experiments are used to measure the laser flux incident on the interface. These, when used in numerical and analytical models, suggest that temperatures reached during the process are enough to produce strain energy release rates to drive delamination of the microstructure from the transfer tool.