E2PROM工艺的ESD保护电路失效分析

ESD保护电路已经成为集成电路不可或缺的组成部分,如何避免由ESD应力导致的保护电路的击穿已经成为CMOSIC设计过程中一个棘手的问题。光发射显微镜利用了IC芯片失效点所产生的显微红外发光现象可以对失效部位进行定位,结合版图分析以及微分析技术,如扫描电子显微镜SEM、微红外发光显示设备EMMI等的应用可以揭示ESD保护电路的失效原因及机理。文章通过对一组击穿失效的E2PROM工艺的ESD保护电路实际案例的分析和研究,介绍了几种分析工具,并且在ESD失效机制的基础上,提出了改进ESD保护电路的设计途径。

Study of Failure in ESD Protection Circuit in E2PROMIC

ESD (electrostatic discharge) protect circuit is an indispensable part in IC. It is a hard problem to avoid over-ESD-stress-induced breakdown in the protection circuit of CMOS IC. Photon emission microscopy is an efficient tool to localize the failure. Layout analysis and micro-analysis methods such as scanning electron microscopy and EMMI were used to find out the cause and the mode of the failure in ESD protection circuit. A batchofbreakdowninESDprotectioncircuitinE2PROMICwerestudied,andsomeFAimplementwereintroduced. Based on the analysis of the failure mechanism some methods to improve the ESD protection circiut were proposed.