P‐10.4: A Non Photolithographic Black Light Shield Film for Ultra‐low Reflectivity Micro‐LED Display

Reflectivity, one of the most key specifications for display, is pursued to be extreme low to match the name of ultimate display for micro-LEDs. Conventionally, black light shield film is fabricated by photolithographic process before or after the micro- LED chips being mass transferred to the driver substrate to meet this requirement. In this study, we report a novel black light shield film material by a simple and effective graphical process to achieve ultra-low reflectivity with little influence on the light output of LED chips to dispense with complicated lithography process, which can fill the gap between the LED chips and the eutectic layer at the bottom of the LED chips, and expose the top of the micro-LED chips simultaneously. The black light shield film was directly adhered to the micro-LED substrate by heating, vacuum and press. Whole surface ashing process was then carried out to remove the excess black light shield film on the surface of the micro-LED substrate. By optimizing the thickness of removed black film, the surface of the micro-LED chips could be exposed while other places were still covered with black light shield film. A full-color Micro-LED display with 114 PPI resolution and size of 1.98-inch was successfully fabricated and showed superb performance with 1.16% reflectivity.