Convention hand polishing, which is widely used for delayering, is becoming increasingly difficult as metal lines and stacks in semiconductor devices get thinner. For one thing, endpointing at the exact targeted layer and region of interest is a major challenge. The presence of cobalt and its propensity to oxidize, thus complicating electrical measurements, is another challenge. In this study, the authors demonstrate an alternative delayering method based on plasma focused ion beam (PFIB) milling aided by DX gas. The workflow associated with the new method is more efficient than that of conventional hand polishing and can help prevent cobalt oxidation.

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