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

Layer-Scale and Chip-Scale Transfer Techniques for Functional Devices and Systems: A Review

“…By shrinking the LED chip size, the LLO technique can be exploited to fabricate ultrathin micro-LED chips, with the major purpose of developing high-resolution micro-LED displays [ 98 , 118 , 130 , 219 , 220 ]. For instance, Kim et al developed a protocol to transfer predefined GaN micro-LEDs to Si by a hybrid approach of combining wafer bonding, LLO, and transfer printing [ 130 ].…”

“…Finally, these tethered chips were picked up using a PDMS stamp and transferred to the final substrate to build functional systems. Alternatively, wafer bonding and LLO are used to transfer lateral LEDs to a temporary substrate, and then transferred to the final substrate by debonding the temporary support [ 98 , 219 ]. While conceptually feasible, these methods are very complicated, and involve the use of expensive wafer bonding, debonding, and transfer printing tools, which are not always available to regular users.…”

“…Chip scale transfer is another direction which has received strong interest from both academia and industry [ 1 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 ]. This is primarily driven by Moore’s law, and the requirement of integrating more functional chips onto one single substrate.…”

“…Therefore, there is growing interest in developing chip-scale assembly techniques with high assembly speed, high yield, and good placement accuracy. The recently emerged micro-LED display technology, for instance, is one of the major driving forces for small chip transfer [ 98 , 99 , 100 , 105 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 ]. Being small, self-emissive inorganic semiconductor devices, micro-LED displays have a number of distinct advantages over conventional LCD and OLED techniques, such as higher brightness, lower power consumption, faster switching, higher contrast, etc.…”

P‐5.7: Selective Laser Lift‐off of GaN Micro‐LED from a Sapphire Substrate Using 266‐nm Solid‐state Laser

“…However, the poor electrical and thermal conductivity of sapphire affect the electrical characteristics and life of the device negatively. Since 355nm solid-state laser was firstly used to peel GaN epitaxial film from sapphire substrate with almost little damage in 1997 [1]- [2] , which establishing the foundation and development of laser lift-off (LLO) technology in LED's fabrication [3]- [6] . Compared to traditional LED, LLO-LED has higher saturation current and luminous efficiency, LLO technology is the one of the focus topics of LED's research directions.…”