37‐1: Yield Statistics for Fault Tolerant Micro LED Displays

Abstract

Millions of μLEDs are transferred from donor wafers and integrated onto TFT backplanes to fabricate a μLED display. To guarantee that the number of defective pixels is zero, a fault‐tolerant design (e.g. redundancy) may be adopted. In this work, the required redundancy level is estimated for a given display resolution, and yields for the μLED donor wafers and the transfer process of μLED to the backplane. This is done using a novel mathematical yield model that is derived from first principles statistics. It is shown that without redundancy the wafer and transfer yields need to be > 99.9999% to hit a display line yield of 80%. With redundancy, the required wafer and transfer yields can be as low as 99.5% with 3× redundancy. The model results may be used to assess the capital requirements and the risk involved in fabricating μLED displays.