Large-scale programmable assembly of functional micro-components for advanced electronics via light-regulated adhesion and polymer growth

Abstract

Large-area, programmable assembly of diverse micro-objects onto arbitrary substrates is a fundamental yet challenging task. Herein a simple wafer-level micro-assembly technique based on the light-triggered change in both surface topography and interfacial adhesion of a soft photo-sensitive polymer is proposed. In particular, the light-regulated polymer growth creates locally indented and elevated zones on the stamp surface. The light-mediated adhesion reduction, on the other hand, facilitates the inks to be released from the polymer. The interplay of these two effects makes it feasible for the programmable assembly of ultra-small components onto various substrates coated with supplementary adhesive layers. The fidelity of this technique is validated by assembling diverse materials and functional devices, with the printing size up to 4-inch. This work provides a rational strategy for large-scale and programmable assembly of diverse delicate micro-objects, bypassing the common issues of some existing techniques such as poor transfer uniformity, small printing area, and high cost.

Laser‐Based Micro/Nano‐Processing Techniques for Microscale LEDs and Full‐Color Displays

“…Micro‐LED mass transfer process [ 9,27–35 ] is widely regarded as one of the biggest obstacles for Micro‐LED display. Being small, ultrathin and fragile, Micro‐LEDs cannot be properly manipulated using a conventional sequential pick and place method.…”

“…Despite the great potential in these applications, the commercialization of Micro-LED displays has been hindered by many technical challenges and the prohibitive manufacturing cost. [25,26] Micro-LED mass transfer process [9,[27][28][29][30][31][32][33][34][35] is widely regarded as one of the biggest obstacles for Micro-LED display. Being small, ultrathin and fragile, Micro-LEDs cannot be properly manipulated using a conventional sequential pick and place method.…”

Printing of Nano‐ to Chip‐Scale Structures for Flexible Hybrid Electronics

“…For instance, TP has been explored for pick‐and‐place of the microchips (≥100 µm) onto flexible substrates with high transfer yield. [ 10 ] Whilst pick‐and‐place approach using elastomeric stamps prove effective for printing large microchips, it is challenging to use the method for ultrasmall chips with ≤100 µm size and/or nanoscale materials with high transfer yield. This is because at these dimensions, i.e., <100 µm adhesion forces including electrostatic, and Van Der Waals on the chip surface may dominate over the gravitational force, as a result these adhesion forces inevitably introduces complication in micromanipulation.…”

“…This is because at these dimensions, i.e., <100 µm adhesion forces including electrostatic, and Van Der Waals on the chip surface may dominate over the gravitational force, as a result these adhesion forces inevitably introduces complication in micromanipulation. [ 10,11 ] Furthermore, UTCs are likely to fail during their transfer as compared to thicker chips due to lower mass and fragile nature. [ 12 ] These challenges could be addressed by “direct roll transfer printing” method, which has been shown to integrate laterally aligned nanoscale and microscale structures with high transfer yield of 95%.…”

“…This is because at these dimensions, i.e., <100 µm adhesion forces including electrostatic, and Van Der Waals on the chip surface may dominate over the gravitational force, as a result these adhesion forces inevitably introduces complication in micromanipulation. [10,11] Furthermore, UTCs are likely to fail during their transfer as compared to thicker Flexible hybrid electronics (FHE) offers potential for fast computation and communication needed in applications such as human-machine interfaces, electronic skin, etc. FHE typically comprises devices that can vary from nano-to chip scale, and their integration using a common process is often challenging.…”