Performance Analysis Tool for Scanning Electron Microscopes Used in Semiconductor Metrology
Michael T. Postek, Andras Vladar, M P. Davidson
Scanning electron microscopes (SEM) are being utilized extensively in the production environment, and these instruments are approaching full automation. Once a human operator is no longer monitoring the instrument''s performance and multiple instruments are concerned, an objective diagnostic procedure must be implemented to ensure data fidelity. One approach to this issue is the sharpness technique. The utility of the sharpness concept for use on production metrology SEMs as implemented through the Fourier transform technique has been clearly demonstrated and documented. The original quantitative methods for sharpness analysis, however, were labor-intensive and therefore not readily suited to the production environment. Recently, these techniques have been integrated into an easy-to-use, stand-alone hardware and software package called SEM MONITOR that makes the analysis far more convenient and user-friendly. Moreover, this program can serve as a prototype for direct integration into a production SEM tool. Analytical data from both laboratory and production instruments demonstrate both the relevance of the sharpness concept and the usefulness of this tool for SEM performance monitoring.