Fabrication And Comparison Of Flip LED Chip With Different Structure

Light Emitting Diode(LED)is widely used in many fields such as conventional lighting,automobile lighting,indicator Light and display screen due to its high reliability,energy saving and environmental protection,fast response and long service life.The LED chip can be divided into formal structure,flip structure and vertical structure.Flip LED chips have attracted more and more attention because of their advantages such as low junction temperature,high reliability and no gold wire packaging.According to the different Reflector layers,the flip LED chips can be divided into silver mirror flip structure and transparent conductive layer(ITO(Indium-Tin Oxide))+Distributed Bragg Reflector(DBR)flip structure.According to the number of different insulation layers,they can be divided into single layer insulation layer(SISO)structure and double layer insulation layer(DISO)structure.In this paper,a stable and mass producible chip technology is developed from the flip chip technology.The flip chips with different structures are prepared,and the performance characteristics of the flip chips with different structures are compared.The main work of this paper mainly includes two aspects:one is to design a stable and mass producible flip-chip process based on the analysis of the existing flip-chip structure and process,including using the Essential Macloed software to simulate and optimize the existing DBR reflectivity,and realize the improvement of the full-angle reflectivity;The preparation method of silver mirror and DBR pattern was developed.Using the different etching rate of platinum(PT)and DBR,a dry etching program of DBR which can realize etching cutoff is developed.On the other hand,mainly optimized ITO+DBR structure,Silver Mirror SISO structure and Silver Mirror DISO structure flip chip version;Based on the optimal version,the driving voltage,luminous power,saturation current,reliability and other properties of the flip-chip with three kinds of structures were compared.Based on performance comparison data,it is concluded that the ITO+DBR structure is more suitable for low-current and highreliability application scenarios,such as Mini LED and Micro LED.The Silver mirror SISO structure is suitable for small and medium size applications,such as flash lamp and flexible filament lamp,which can withstand large current pulse.The Silver mirror DISO structure is suitable for large size chip applications with large current and high brightness,such as car headlights and special lighting,etc.