Study Of Highly Reliable Laser-driven Chips Transfer Technology

Micro light-emitting diode(MicroLED/?LED)is a new generation of display technology in the future due to its low power consumption,low cost and long life.After the fabrication of MicroLED chips,millions of MicroLED chips need to be transferred from the wafer to the driver circuit substrate,namely mass transfer technology.Because the laser has the advantages of high processing efficiency and convenient patterning,this paper chooses the laser-driven method to realize the transfer of the chips.At present,the research on laserdriven chips transfer is not enough,this paper discusses the four important links of laserdriven MicroLED chips transfer process: transfer threshold and transfer accuracy measurement,threshold optimization,accuracy optimization,and experimental equipment design and construction.The main research is as fellows:1.Participated in the construction of laser lift-off experimental equipment,and based on this equipment,researched the transfer threshold,transfer accuracy and process mechanism of the laser-driven chips transfer process.By adjusting the laser energy density and the adhesion of the adhesive layer,the threshold interval for the chips to be successfully transferred is obtained.By changing the distance between the chips and the receiving substrate,the relationship between the transfer accuracy and the distance is obtained.By measuring the bubbling height of the dynamic release layer under different working conditions,the process mechanism of the laser-driven chips transfer is explained.2.Aiming at the problem that the threshold range of the laser-driven chips transfer process is small,the thermal release adhesive interface adhesion control is proposed to optimize the threshold.The transfer threshold is optimized by changing the adhesion of the same dynamic release layer at different times by using thermal release adhesive.The experimental results show that by adjusting the interface adhesion of the thermal release adhesive,the adhesion of the dynamic release layer can be reduced from very high to very low,thereby improving the transfer success rate and expanding the threshold range.3.Aiming at the problem of low transfer accuracy of the laser-driven chips transfer process,the magnetic force-induced self-positioning of the chips is proposed to optimize the transfer accuracy.The transfer accuracy is optimized by the aid of an external magnetic field.The experimental results show that the magnetic force-induced self-positioning of the chips can ensure the transfer accuracy under a larger transfer gap,which can be doubled compared with the previous method.4.Participate in the design and construction of mass transfer experimental equipment.Participate in the process flow,the structural design of each component,the overall layout and the assembly of the mass transfer equipment.Self-developed mass transfer equipment,which mainly integrates 308 nm excimer laser,patterned optical path,high-precision motion platform,positioning and observation systems.Through the equipment,MicroLED chips can be accurately positioned,transferred in batches and patterned,and compatible with realtime observation,eliminating bad chips and repairing bad chips.