Development of FIB-based Charge Reduction Methods for Auger Electron Spectroscopy and Their Application in Failure Analysis

Surface charging is encountered in the study Auger electron spectroscopy of non-conducting surfaces. In this paper, two case studies of (i) Au-pad of packaged die unit and (ii) floating Al-pads of patterned wafer were presented. Surface charging was noticed in both the samples and it was not possible to eliminate the effect with convention charge reduction methods. Two FIB-based methods of charge reduction with potential applications in a failure analysis lab were discussed. The essence of techniques is to provide conducting path to charge accumulated on the surface of specimen. This is achieved by drawing Pt wires using FIB technique. In one of the methods discussed, Pt wire is deposited and patterned in the vicinity of feature of interest while, in the second technique a hole is drilled to Si substrate using a laser source and followed by Pt deposition. Both the methods were effective in reducing surface charge, thus aiding in Auger data collection