Wafer level bonding poses significant technical challenges and had not previously been achieved between a GaN-on-Silicon microLED wafers and a high-density CMOS backplanes, claims Plessey who says it achieved the world’s first mechanically successful wafer to wafer bond in early April 2019. This follows a continued partnership with JDC including an extensive capital investment in a complete tool set, enabling successful wafer to wafer bonding.
This new milestone lead to a fully functional, electrical and mechanical bond, resulting in a fully operational microLED display. The display features an array of 1920x1080 (FHD) current-driven monochrome pixels on a pitch of 8 microns. Each display requires more than two million individual electrical bonds to connect the microLED pixels to the controlling backplane. The JDC backplane provides independent 10-bit single colour control of each pixel – Bonding a complete LED wafer to a CMOS backplane wafer, incorporates over 100 million micro level bonds between the wafers.