TVS短路失效机理分析

Analysis on Short-circuit Failure Mechanisms of Transient Voltage Suppressor

常用电路保护器件的主要失效模式为短路,瞬变电压抑制器(TVS)亦不例外。TVS一旦发生短路失效,释放出的高能量常常会将保护的电子设备损坏,这是TVS生产厂家和使用方都想极力减少或避免的情况。通过对TVS筛选和使用短路失效样品进行解剖观察获得其失效部位的微观形貌特征,结合器件结构、材料、制造工艺、工作原理、筛选或使用时所受的应力等,采用理论分析和试验证明等方法分析导致TVS器件短路失效的原因。分析结果表明引发TVS短路失效的内在质量因素包括粘结界面空洞、台面缺陷、表面强耗尽层或强积累层、芯片裂纹和杂质扩散不均匀等,使用因素包括过电应力、高温和长时间使用耗损等。

The primary failure mode of commomly used circuit protective devices is short-circuit, and so is TVS （Transient Voltage Suppressor） . When the TVS is shorted, the release of high energy often damages the protected electronic equipment, which is strongly desired to be reduced or avoided by TVS manufacturers and users. Some shorted TVS failed in the screen tests and the applisation were sectioned to observe their microscopic appearance features. The failure mechanisms of the samples were analyzed by theoretical analysis and test proving, based on the devices＇ structure, materials, manufacturing process, working principle or withstanded stresses in the screen tests and application. It is shown that the intrinsic quality factors caused shortcircuit faihue of TVS include bonding interface voids, mesa defects, strong surface depletion layers and strong accumulation layers, cracks in wafer and impurities diffusion inhomogeneous, and the extrinsic reasons include electrical over-stressing and high temperature.