多层介质电容失效分析

Multilayer Dielectric Capacitor Failure Analysis

针对GaAs MMIC因电容失效而导致性能异常的问题,分析了电容失效模式及失效机理。对GaAs MMIC中多层介质电容的制作过程进行了重点监控,分析了电子束蒸发工艺缺陷对多层介质电容失效的影响。基于扫描电子显微镜(SEM)及能谱仪(EDX)分析,研究了电容基板金属颗粒对电容失效的影响。结果表明,电子束蒸发工艺产生的金属颗粒造成短路是电容主要失效模式。蒸发难熔金属时,在金属源形成的深坑导致蒸发速率瞬时增大,产生的大量金属颗粒造成电容极板短路,从而导致电路性能异常。最后,对金属蒸发工艺参数进行优化,采用分段蒸发增加熔源过程的方法降低了电容失效率。

The failure model and failure mechanism of the capactior were analyzed for the performance anomaly of the GaAs MMIC caused by the capacitor failure. The fabrication process of the GaAs multilayer dielectric capactior was monitored emphatically to analyze the influence of the electron beam evaporation process defect on the multilayer dielectric capacitor failure. The influence of the metal particles of the capacitance base on the capacitor failure was analyzed by the SEM and EDX. The results show that the main failure model is the short caused by the metal particles in the electron beam evaporation process. The pit in the metal source formed in the evaporation process of the high melting point metal would lead the greatly increase of the evaporation rate instantaneously,which could produce lots of metal particles on the capacitance base. The metal evaporation would cause the short of the capacitance plate,which leads to the circuit performance anomaly. Finally,the metal evaporation process parameters were optimized and the failure rate of the capacitor was reduced by increasing the melting process of the evaporation source segment.