影响倒装焊LED芯片电流分布均匀性的因素分析

Analysis of influencing factors on current spreading of flip-chip light-emitting diodes(LEDs)

为研究影响倒装LED芯片电流密度均匀分布的因素,建立了芯片的三维有限元电学模型,采用COMSOL有限元仿真方法,分析了芯片尺寸、电极结构、电流注入点对倒装LED芯片电流分布均匀性的影响,并对相关机理进行了探讨.研究结果表明,芯片尺寸的增加扩展了电流的横向传输路径与横向电阻,使LED芯片电流分布的不均匀性呈指数型恶化;叉指式电极结构可有效缩短电流传输途径,增加叉指电极数目有利于电流均匀性的提高;通过在块状电极上合理设计电流注入点可缩短电流传输路径,显著提高电流的均匀性.

In order to research the factors that affect the current uniformity of flip-chip LEDs, the three-dimensional model of LED chip is established by the finite-element analysis software COMSOL4.0. The influences of chip size, electrode structure and current injection bump on the electrical property of the LED are investigated. The simulation results show that the non-uniform current distribution of LED chip changes exponentially with the increase of the chip size. Interdigitated electrode structure can reduce the lateral resistance effectively by shorting the channel that current flows through. The reasonable design of the bump on the block electrode can also make current even by reducing the lateral resistance.