P‐1: Development of High‐yield Laser Lift‐off Process for Micro LED Display

Abstract

This paper reports our developments for Micro LED laser liftoff which is a very important step in Micro LED mass transfer process. By selecting the temporary bonding material, optimizing laser power intensity and other process parameters, the yield of Micro LED laser lift-off can reach 99.87% for more than 1500 LEDs. This technical developments is of great potential for promoting high-yield mass transfer technology to realize commercial Micro-LED displays.

Infra‐Red Intelligent Surface for Near‐Field Touchless Displays

“…Photo emitters and receivers that are used for this sensor technology are quite similar to the RGB pixels being developed for microLED screens. This means that the same kind of mass‐transfer methods can be employed to transfer the IR micro‐elements as the RGB pixels, such as laser lift‐off, 2 mechanical transfer, and fluidic assembly 3 . This implies that the processes to make microLED displays and IRIS‐enhanced microLED interactive displays will be alike and add little additional complexity to the fabrication process.…”

Highly effective transfer of micro-LED pixels to the intermediate and rigid substrate with weak and tunable adhesion by thiol modification

“…16,18,19 GaN-based micro-LED pixels are usually separated from the sapphire epitaxial substrate by laser lift-off (LLO). In this process, laser absorption through the underside of the transparent sapphire occurs at the undoped GaN/sapphire interface, which causes the undoped GaN buffer to decompose into nitrogen (N 2 ) and gallium (Ga) droplets, 10,20 and the pixels are thus separated from the sapphire substrates and transferred to the acceptor substrate. During the LLO, to ensure that the pixels are not displaced or missing, an acceptor substrate with strong adhesion is required to accept the pixels, most of which are polymer tapes that are relatively strongly sticky and flexible (such as semiconductor wafer processing (SWP) tape and polyimide (PI) tape).…”

A Novel Compliant 2-DOF Ejector Pin Mechanism for the Mass Transfer of Robotic Mini-LED Chips

“…At present, the mass transfer technology of micro-LED can be mainly summarized as following: (1) the electrostatic transfer method for chip operation by using electrostatic adsorption force [12]; (2) elastic stamp transfer using van der Waals force to absorb and release chips [13][14][15]; (3) laser-assisted transfer technology using a laser-point melting chip adhesion layer [16,17]; and (4) self-assembly technology using a fluids journal [18]. However, there are some problems with these technologies, such as the need for special materials on the chip adhesion layer and the high cost of spare parts.…”