联用动态EMMI与FIB的集成电路失效分析

EMMI被广泛应用于集成电路的失效分析和机理判定。针对端口I-V特性曲线的异常现象,采用静态电流的发光效应对漏电点进行光发射定位。静态电流法无法全面测试集成电路内部逻辑单元,需要使用动态信号驱动集成电路,使内部失效部位能够产生光发射。对样品在动态失效工作状态进行光发射捕捉,再结合良品对比、电路原理图和版图分析等辅助手段进行故障假设,以定位失效点,最后利用FIB系统对电路进行剖面切割制样,找出物理损伤点。对砷化镓数字集成电路的不稳定软失效案例进行分析,动态EMMI法与FIB系统联用可成功应用于芯片内部金属化互连异常的失效分析,解决传统静态光发射法无法定位的技术难题。

FIB Assisted Dynamic EMMI Used for Failure Analysis of ICs

EMMI had been widely used in failure analysis and mechanism estimation of ICs. Emission effect of static current was adopted to locate the leakage spots confirmed by abnormal I-V characteristic curve. However, internal logic units were not able to be tested exhaustively by static current method. In order to generate photon emission in the area of internal failure spots, dynamic method was developed to drive the ICs with signal input. Photon emission collection was performed when the device was working in dynamic failure state, then comparisons with good reference, circuit schematic and layout analysis were used to establish a defect hypothesis to locate the failure spots. With the assistance of focus ion beam(FIB), cross-sectional sample preparation was carried out to give the physical defect spots. Case analysis of unstable soft defects in GaAs digital ICs was performed. Dynamic EMMI combined with FIB could successfully be used for failure analysis of internal metal interconnection failure in the ICs, and could solve the problem that the traditional static EMMI was not able to locate the failure spots.