电压衬度在CMOS集成电路失效分析中的应用

Application of Voltage Contrast in CMOS IC's Failure Analysis

电压衬度(Voltage Contrast,VC)是CMOS集成电路失效分析的一种有效方法。电压衬度主要利用二次电子的发射效率与样品表面电势相关的原理。通过数据分析、电学测试等流程缩小搜索范围,再利用电压衬度原理进一步缩小范围,通过FIB精准定位缺陷并进行剖析,最终找到失效根源。作者探讨电压衬度原理,并通过具体案例,对电压衬度分析在扫描电子显微镜(Scanning Electron Microscope,SEM)以及聚焦离子束(Focused Ion beam,FIB)的运用作了详细阐述。

The Voltage Contrast localization is an effective method in CMOS IC＇ s Failure analysis. VC imaging takes advantage of differing secondary electron emission efficiencies with surface potential on ICs. Using data analysis and electrical testing to narrow the searching area, voltage contrast was then used to further locate the defect position, finally precision cutting by FIB was applied to dissect the defect and root cause of failure was found. In this paper, the principle of voltage contrast was introduced, and how to apply VC method on SEM and FIB to locate the defect was described by three cases.