Defect localization has become more complicated in the FinFET era. As with planar devices, it is still generally possible to electrically isolate a failure down to a single transistor. However, the complexity of certain FinFET devices can lead to ambiguity as to the exact physical location of the defect. The default technique for isolating the defect location for this type of device is to start with a plan view S/TEM lamellae. Once the defect is located in plan view, the lamellae can be converted to cross-section (if necessary) for further characterization. However, if the defect is not detectable in plan view S/TEM analysis, an alternative approach is to examine the device in cross-section along either the x- or y- axis. Once the defect is located in the initial cross-sectional lamellae, it can be converted to the orthogonal axis if the initial cross-sectional lamellae did not provide adequate information for characterization. However, in converting a cross-sectional lamellae to the orthogonal axis, the initial lamellae must be exceedingly thin due to the dimensions of devices on 1x nm FinFET technologies, else other structures on the sample can obscure the view in the S/TEM. This can lead to structural integrity (warping) issues for the converted lamellae. In this paper, a novel solution to the warping issue is presented.

The modern scanning transmission electron microscope (S/TEM) has become a key technology and is heavily utilized in advanced failure analysis (FA) labs. It is well equipped to analyze semiconductor device failures, even for the latest process technology nodes (20nm or less). However, the typical sample preparation process flow utilizes a dual beam focused ion beam (FIB) microscope for sample preparation, with the final sample end-pointing monitored using the scanning electron microscope (SEM) column. At the latest technology nodes, defect sizes can be on the order of the resolution limit for the SEM column. Passive voltage contrast (PVC) is an established FA technique for integrated circuit (IC) FA which can compensate for this resolution deficiency in some cases. In this paper, PVC is applied to end-pointing cross-sectional S/TEM samples on the structure or defect of interest to address the SEM resolution limitation.