From mobile phones, TVs, to cars and public screens, displays have become an important component in daily life to convey information. The importance of displays becomes more significant during COVID-19, as the demand to have a display for remote communication is higher.
There is an emerging display type – Micro-LED display, which has the potential to become the next-generation mainstream, with its ability to be fabricated from tiny to huge sizes. The challenges and opportunities are discussed in the IDTechEx report ‘Micro-LED Displays 2021-2031: Technology, Commercialization, Opportunity, Market and Players’.
COVID-19 has not stopped the development of Micro-LED displays. With CES and Display Week, as well as a number of events being put online, we can see the progress and new launches of Micro-LED display prototypes and products are not affected much.
The increasing number of activities from display suppliers can be seen from the highly cumulated investment and the increasing number of patent filings, as well as the prototypes/products brought in by Micro-LED vendors, such as AUO, PlayNitride, RiTdisplay, Samsung, LG, Sony, TCL, Tianma, Konka, Glo, Plessey, JBD, X-Display, VueReal, CSOT, Sharp, Kyocera; the list can go on.
However, prototypes to prove technology/science readiness with lab/fab scale production are very different from mass manufactured commercial products. The latter requires zero defects for consumer products. Although the science has been proved, there are more engineering and manufacturing issues. For instance, conventional LEDs can reach external quantum efficiencies (EQEs) to ~70%, while tiny Micro-LEDs less than 10µm may struggle to reach 20%.
Red LEDs are especially challenging with low EQEs and brittle features. Tiny Micro-LEDs have a large surface area, which may lead to more defects during the fabrication process. Therefore, solving engineering/manufacturing challenges is important, including die size miniaturization while maintaining high efficiency, chip design, and chip manufacturing technique improvement. Other issues include mass transfer yield & accuracy, defect repair, testing, uniformity, light management, color conversion, etc.
To fabricate a Micro-LED display, many technologies and processes are involved, such as epitaxy, photolithography, chip fabrication, substrate removal, inspection, mass transfer, bonding and interconnection, testing, repair, backplane and drive IC, etc. After years of development, some technology difficulties have been solved, while new challenges sit in front of us.
For instance, several years ago, the major efforts were concentrated in die miniaturization, chip design. and mass transfer, etc. Recently, more and more players realize a complete understanding of all the processes is the key. Therefore, more people also put increasing efforts on technologies such as inspection, repair, driving, image improvement, light management, and high-volume production equipment.
Another interesting phenomenon is the increasing number of partnerships, mergers, acquisitions, joint ventures, and further investment. This aligns with the display cycle trend. There was hype in the Micro-LED display one or two years ago and now major players gradually find their roadmap. Mini-LED displays and large signage & TVs are approached by many vendors and players are still working on Micro-LED displays in the meantime. Compared to previous years, consolidation becomes more obvious.
Following on with the LCD industry, China has invested a lot in Micro-LED displays again. Before 2019, BOE was not active in the Micro-LED display area. However, after 2019, BOE jumped to be the top company in terms of patent filing numbers. Large investment also indicates huge interests. Although there are quite a few start-ups in Europe and America, it seems East Asia will be dominating in the Micro-LED display development.