Abstract
GaN-based microscale light-emitting diodes (μLEDs) are reported for assembly into deformable displays and repair systems. A stamp-imprinting method that enables large area assembly without spatial limitation is involved in the system, and a selective pick-up method is presented that includes a method for removing detected defective chips through micro-pulsed laser scanning. The photosensitive functional material, which is an accepted layer for the stable imprinting of chips, is determined by controlling the adhesion. In addition, selective pick-up and adhesion-controlled functional materials allow the implementation of defect-free displays through two pick-and-place cycles. Displays and related systems fabricated with this method can offer interesting optical and electrical properties.
Highlights
Ultra-high-resolution displays have attracted attention because of the development of applications such as smart phones, glass monitors, and virtual-reality devices
The microscopy images of Figure (b) show that defective chips remain on the μLED wafer and only good chips are picked up on the stamp
The defective chips of the μLED wafer are detected by micro-pulsed laser scanning
Summary
Ultra-high-resolution displays have attracted attention because of the development of applications such as smart phones, glass monitors, and virtual-reality devices. Considering manufacture of displays with a higher pixel density, this method is not the ultimate solution because it is difficult to secure space for a spare chip The solution to this problem is the top priority for manufacturing μLED displays using stamp-imprinting. The transfer is defined in four steps as follows: (i) Analysis of the defective chips in a μLED wafer, (ii) selective pick-up from μLED wafer to stamp, (iii) imprinting of the μLED array to the board substrate using a functional layer capable controlled-adhesive force, and (iv) repair. The stamp used to transfer the μLED array from the wafer to the board substrate is polydimethylsiloxane (PDMS), which is a dry adhesive silicone rubber[19,20] These picked-up good chip arrays are imprinted on a board substrate with a UV-photosensitive thin film. To verify the stamp-imprinting method developed in this study, we fabricated a passive-matrix prototype after transferring single chips and a 10 × 10 array to a deformable polyimide (PI) substrate
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