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A new optical alignment artifact under development at NTST is described. This artifact, referred to as a stepped microcone, is designed to assist users and manufacturers of overlay metrology tools in the reduction oftool-induced measurement errors. We outline the design criteria and diamond turning lathe techniques used for manufacturing this structure. The alignment methods using this artifact allow the separation of error components associated with the optical system or the mechanical positioning systems as encountered when performing measurements in different focal planes. Although some difficulties have been encountered in the actual diamond turning process, the data presented show some improvements with the more recent prototypes which indicate that this method offabrication will be useful. Photometer scan data and CCD image acquisition hardware show a significant optical response at the step edges from these structures.

The Rapidly Renewable Lap (RRL) uses a textured substrate over which thin films are slumped (Figure 1). The substrate provides the geometry of the lap and a localized texture, depending on the film thickness, properties, and how it is deformed over and adhered to the substrate. Abrasives, added to the film, lap or polish without touching or changing the substrate geometry. Depending on process parameters, the RRL gives brittle or ductile lapping and polishing.