FA Approach on MIM (Metal-Insulator-Metal) Capacitor Failures

Abstract

MIM (Metal-Insulator-Metal) capacitor is a capacitor fabricated between metal layers and usually in an array form. Since it is usually buried within stack of back-end metal layers, neither front side nor backside FA fault isolation techniques can easily pinpoint the defect location of a failing MIM capacitor. A preliminary fault isolation (FI) often needs to be performed by biasing the desired failing state setup to highlight the difference(s) of FI site(s) between failing unit & reference. Then, a detailed study of the CAD (Computer Aided Design) schematic and die layout focusing on the difference(s) of FI site(s) will lead to a more in-depth analyses such as Focused Ion-Beam (FIB) circuit edit, micro-probing/nano-probing, Voltage Contrast (VC) and other available FA techniques to further identify the defective MIM capacitor. Once the defective MIM capacitor was identified, FIB cross-section or delayering can be performed to inspect the physical defect on the MIM capacitor. This paper presents the FA approach and challenges in successfully finding MIM capacitor failures.