Focused ion beam sample preparation, transmission electron microscopy and electron energy loss spectroscopy analysis of advanced CMOS silicon technology interconnections

Abstract

In this paper we present a dedicated technique using focused ion beam etching for transmission electron microscopy sample preparation of advanced CMOS interconnections. We show that the etching advantages are: very precise localisation allowing for thinning of small diameter contacts even when made of hard material such as tungsten or titanium nitride. The very low thickness obtained allows for high magnification observation and chemical analysis of the diffusion barrier at the bottom of small contacts by means of electron energy loss spectroscopy.