钝化材料对深紫外LED器件性能的影响

Effects of Passivation Materials on Performance of Deep Ultraviolet LEDs

对比研究了SiO2、聚酰亚胺薄膜、SiNx/旋涂玻璃(SOG)复合材料等钝化材料对倒装焊深紫外LED器件抑制漏电流恶化、改善器件可靠性的作用。实际测试结果表明,未钝化和采用SiO2、聚酰亚胺、SiNx/SOG复合钝化膜后,倒装焊紫外LED短路漏电比例分别为100%、100%、55%和18%,采用聚酰亚胺和SiNx/SOG复合钝化膜的器件点亮1 000h后光衰分别为67%和20%。分析表明,SiNx与SOG结合使用有效降低了表面电荷复合几率并改善了倒装焊短路问题;SOG还进一步降低了表面的粗糙度,改善了由于AlGaN外延表面上的深凹槽结构引起的器件漏电及倒装焊金属溢流的短路,从而大大提高了可靠性。

The effects of silicon dioxide （SiO2）, polyimide, silicon nitride （SiNx）/spin-onglass （SOG） layer on the current leakage and the stabilities of deep ultraviolet LEDs were studied. The results show that for LEDs with no passivation, or with SiO2 layer, polyimide layer and SiNx/SOG layers, the leakage ratio is 100%, 100%, 55% and 15%, respectively. After the burn-in time exceeds 1,000 hours under stress test condition, theoptical power degradation of the latter two types is 67% and 20%, respectively. The analysis shows that the application of the SiNx/SOG passivation can both reduce the surface charge recombination rate and alleviate electrode shorts during flip chip bonding. In addition, the ability of SOG to planarize rough surface has reduced electrode shorts and surface leakage resulted from pits and bumps of the epitaxial AlGaN layer, therefore, the performance and lifelime of deep ultraviolet LEDs are improved dramatically.