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There are some possible artifacts in PVC (passive voltage contrast) in FIB and SEM observations. One type of artifacts originates from deprocessing of IC chips because the PVC observations are often done after deprocessing. Figure 3859a shows that the metal layer was removed by deprocessing so that the gate is bright and appears floating due to positive charging. However, this contrast is actually an artifact because of deprocessing.

Figure 3859a. Artifacts in PVC (passive voltage contrast) due to IC deprocessing.
Another possibility having contrast artifact is that the conducting lines was destroyed (cut) with FIB as shown in Figure 3859b. In this case, the piece of floating metal is positively charged and appears dark in SE images.
Figure 3859b. Contrast artifact of PVC caused by FIB cutting.
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