芯片漏电会对LED灯珠稳定性和寿命造成很大影响,为此本文对LED样品的漏电失效机理进行了研究。在微光显微镜观测下,样品的芯片正电极位置存在漏电异常。利用氩离子精密刻蚀系统对样品进行截面制样,并采用扫描电镜进行观察,分析可能导致漏电的原因。SEM下观测到漏电样品芯片正极出现空洞,且空洞对应的外延层出现较明显的裂缝。分析认为,在焊接时电极产生空洞,在后续高温回流焊、封装和使用过程中压力和应力集中在裂缝处,使GaN外延层受损导致漏电。研究结果为LED芯片漏电检测手段、机理分析提供了良好的参考方案,并为解决芯片裂缝和空洞问题提供了理论参考方向。

The failure mechanism of leakage in LED samples was studied. Since leakage has a negative impact on LED quality, it is necessary to analyze how the process works on the leakage. Two groups of failure samples were selected for study. Through testing, there are abnormal leakage at the positive electrodes under the emission microscope. The section of the sample was prepared by fully automated argon ion polishing system and observed by scanning electron microscope. SEM observation showed that in the chips there were holes in electrodes and obvious cracks in the epitaxial layer corresponding to the holes. According to the analysis, electrode cavity is generated during welding. In the subsequent high-temperature reflow welding, packaging also using process, pressure and stress are concentrated at the crack, which causes damage of GaN epitaxial layer and leads to electric leakage. It provides a good reference scheme for LED chip leakage detection means and mechanism analysis. Whats more, it provides a theoretical reference direction for reducing chip cracks and holes.