Consideration of a Ga-FIB in Lamella Sample Prep for EBIC/EBAC Analysis of Advanced-Node SRAMs

Abstract The effects of sample prep with a Ga+-ion Focused Ion Beam (Ga-FIB) on measurements of electron beam induced current (EBIC) were studied. Concerns have been occasionally raised about amorphization from the beam, or even Ga+ implantation ruining the ability to make useful measurements for purposes of either failure analysis or device tailoring. To understand the magnitude of any deleterious effects, two different lamellae from a 5 nm SRAM sample were prepared with different areas of increasingly improved polish, as indicated by decreasing, cumulative, FIB beam energy, followed by EBIC measurements at 1 or 2 kV beam landing energy. A first experiment looked at the ability to generate EBIC measurements from depletion zones and found no difference across the various beam polish cells. A second experiment considered leakage and/or shorts and found little problematic currents, within standard deviations.