High bonding yield and brighter integrated GaN LED and Si-CMOS

To improve the bonding yield and the brightness of the final integrated Si-CMOS + GaN LED wafer, two issues need to be addressed. The first problem is the surface protrusions such as melt-back etching and hillocks which are the common surface imperfections on the surface of GaN/Si substrates. This prevents the direct contact of the two wafers and create unbonded area. To address this, a CMP process that using conventional SiO
₂
slurry with additional diamond nanoparticles is carried out on the GaN (LED)-on-Si wafer prior to the bonding to the Si-CMOS wafer. The second issue is the Si substrate of the GaN LED wafer absorbs photons which lowers the light emitting efficiency of the LEDs. We address this issue by transferring the Si-CMOS + GaN LED films from the Si (111) wafer to a transparent quartz substrate. By addressing these issues, a high bonding yield and high brightness of Si-CMOS + GaN LED on quartz substrate is realized.