A new optical alignment artifact under development at NIST is described. This structure, referred to as a stepped microcone, is designed to assist users and manufacturers of overlay metrology tools in the reduction of tool-induced measurement errors. We outline the design criteria and diamond turning lathe manufacturing techniques used for 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 machining processes, the data presented show some recent improvements and that this method of machining will be useful. Photometer scan data and CCD image acquisition hardware show a significant optical response form these structures at the step edges. Initial analysis of the optical response of these edges shows sensitivity to the materials choices and detailed manufacturing processes.
Proceedings Title: Proceedings of SPIE, Metrology, Inspection, and Process Control for Microlithography XI, Susan K. Jones, Editor
Conference Dates: March 10, 1997
Conference Location: Santa Clara, CA
Conference Title: Registration and Overlay I
Pub Type: Conferences
diamond turning lathe, induced measurement errors, optical alignment artifact, optical response step edges, stepped microcone, tool-induced measurement errors