Auger Sputter Depth Profiling Applied to Advanced Semiconductor Device Structures

Abstract

ABSTRACTThe continuing miniaturisation of modern semiconductor devices is placing new demands on the spatial resolution of many existing assessment techniques. With device structures reduced to nm dimensions the need to optimise conditions for high resolution in-depth profiling is essential for accurate characterisation. In this paper we present Auger profiles of two micro-electronic structures and consider the choice of ion beam parameters necessary to minimise ion beam induced distortion. In VLSI (Very Large Scale Integration) technology where high dopant concentrations are ion implanted into shallow layer structures, Auger profiling can be used to establish dopant distributions accurately in the peak regions of the high dose implant. This information is shown to provide data for process modelling programmes.Also presented are profiles of MOCVD (Metal Organic Chemical Vapour Deposition) grown GaAlAs/GaAs superlattices with 70 Å repeat structures. Interface width measurements are of particular importance in this case where sharp interfaces are a pre-requisite for good device performance. These structures have been found to be very vulnerable to enhanced atomic mixing, a consequence of the small mass of the Al atom. The Al content of the GaAlAs determining the obtainable in-depth resolution.