Consideration of a Ga-FIB in Lamella Sample Prep for EBIC Analysis of Advanced-node SRAMs

An experiment to understand possible detrimental effects from processing SRAM samples with gallium focused ion beams (Ga-FIB) prior to electron beam induced current (EBIC) characterization is presented. To understand the magnitude of sample surface amorphization upon the ability to collect EBIC measurements, a lamella was prepared with different areas of increasingly improved polish, followed by EBIC measurements at 1 and 2 kV beam landing energy. The results indicate that EBIC measurements on a 5 nm SRAM lamella are minimally impacted by variations in final FIB polishing optimization, a reminder that these measurements are interacting with a volume in the sample, rather than merely the surface. A second experiment showed the ability to perform high-magnification EBIC measurements underneath gates.