Novel techniques to expose substrate-level defects are presented in this paper. New techniques such as inter-layer dielectric (ILD) thinning, high keV imaging, and XeF2 poly etch overflow are introduced. We describe these techniques as applied to two different defects types at FEOL. In the first case, by using ILD thinning and high keV imaging, coupled with focused ion beam (FIB) cross section and scanning transmission electron microscopy (STEM,) we were able to judge where to sample for TEM from a top down perspective while simultaneously providing the top down images giving both perspectives on the same sample. In the second case we show retention of the poly Si short after removal of CoSi2 formation on poly. Removal of the CoSi2 exposes the poly Si such that we can utilize XeF2 to remove poly without damaging gate oxide to reveal pinhole defects in the gate oxide. Overall, using these techniques have led to 1) increased chances of successfully finding the defects, 2) better characterization of the defects by having a planar view perspective and 3) reduced time in localizing defects compared to performing cross section alone.

An ARC solution that can be used to improve backside imaging for backside photoemission microscopy applications is presented in this paper. Zinc Oxide (ZnO) -based thin films used as ARCs are deposited at the backside of the failing units through a simple and low cost spray pyrolysis technique. An improvised set-up, composed of an atomizer and a hot plate, is used in the experiment. The paper provides evidence of acceptable process repeatability and demonstrates that the technique and the material have important applications in the field of failure analysis. Furthermore, it shows that the application of ARC resulted in better defect localization. The location of the defect is easily been determined upon doing frontside inspection - to - backside image comparison on the deposited unit. By using high kV ion beam passive voltage contrast (PVC) and angled cut focused ion beam (FIB) cross section, we are able to isolate further and show the nature of the defect at the failing block.