Use of Electron Beam Position Modulation in Auger Depth Profile Analysis

摘要

By combining Auger analysis with ion etching, the scanning Auger microprobe (SAM) provides 'three-dimensional' composition information not readily obtainable from other analytical methods. As this technique is being applied to the analysis of microelectronic devices with increasingly smaller dimensions, two major limitations become evident: (1) features of interest in microelectronic circuits are often comparable in size to the beam diameter of commercial Auger microprobes, and (2) the electron beam tends to drift on the specimen surface because of mechanical instability and differential thermal expansion. Because Auger Depth profiling requires relatively low sputter rates for good depth resolution, depth profiles of small features can be seriously degraded by beam drift. In this report, we describe a technique that will eliminate the error and uncertainty caused by beam instability. In our technique, the analyzing beam is scanned repetitively across the feature to be profiled, and the Auger signal is synchronously detected at the scan frequency. The resultant Auger signal magnitude is shown to be unaffected by beam drift when compared to conventional detection methods. (Author)