Study Of Bonding And Laser Lift-Off Technology Of Vertical Structure Light Emitting Diodes

Light emitting diode(Simplified as LED)is a kind of solid state semiconductor device.It can convert electric energy into light energy directly.Vertical structure light emitting diode benefits in the specific structure as a kind of LED,it has a characteristics of good heat dissipation and high brightness.So in the specific lighting area the VLED has been applied spreadly.At present.the technology of VLED is complex and the cost is high,furthermore the key technology patents are held in foreign large factories,all these leads to the slow development of domestic VLED.In the article we mainly focused on the two specific technology during the manufacture of VTF LED.Firstly,the bonding technology,it is a technology that can transform the GaN epitaxy into another substrate.Secondly,the Laser lift-off technology,it is a technology that can separate the GaN epitaxy from sapphire substrate.The aim of studying the bonding technology is to improve the peeling problem after the bonding process.Now the bonding technology uses the Ni-Sn bonding instead of Au-Au bonding to reduce the cost.but as the bonding process window is small it is resulted in the bonding yield rate decreaSing.Based on the studying of the article,we can get the proper metal structure Ti/Ni/Sn(3/5/10KA)of Ni-Sn bonding technology,it is the best appearance after bonding.We import Ni-Sn bonding into CuW substrate products,the bonding transfer rate is over 98%and no dark cracks and fragments.It can be mass produced.Furthermore,we also reduce the substrate warpage degree by uSing the sapphire substrate and the CuW substrate to temporarily bond.Through a series of experiments,we confirmed the temporary bonding conditions and the process flow.Finally,we reduced the warpage degree from 400?m to under 180?m.The exposure process and improve production efficiency.By importing this technology into CuW substrate products,the test yield of the product increased by about 5%and the appearance yield increased by about 8%.For the laser lift-off is utilizing the GaN to absorb the laser energy and pyrolysis as Ga and N2 instantly that makes the epitaxy separate from sapphire substrate.The purpose of studying the Laser lift-off technology in this article is to adjust the laser and its stripping mode for the DPSS substrate to improve the imprint which produced after Laser lift-off and enhance the chips appearance yield rate.In addition,we optimized the rinSing process after laser lift-off and improved the fragment percent during the laser lift-off and sharply reduced the difficulty in the following operation.The data from the volume operation show that the fragmentation rate has decreased by 21.6%.