Extending particle characterization limits in wafer processing

As analytical tools are called on determine ever-smaller particle size, the use of a scanning electron microscope with energy-dispersive x-ray spectroscopy (SEM/EDS) becomes inadequate for ascertaining the origin of microparticles. Additional methods other than SEM/EDS are required, featuring improved surface sensitivity, low-z material capability, and some chemical identification capability. This paper presents a case study on a specific process-induced contamination problem - the recurring formation of small aluminum-containing spheres during metal etch - and gives practical illustrative examples where SED/EDS must be augmented by other techniques.