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7 December 1994 Technical performance of the ALTA-3000 laser writer
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Mask precision specifications continue to become more stringent with the advent of 64 Mb and 256 Mb DRAM fabrication. At the same time, data density per mask layer has increased and the data address size has decreased, limiting mask throughput. The first ALTA-3000 laser mask lithography system has recently been factory acceptance tested and is in the process of being installed in the IBM mask fabrication facility. The Etec ALTA-3000 is a new mask lithography system utilizing advanced scanning and data-path technology to meet the performance and throughput requirements of advanced mask manufacturing needs. A 32- channel parallel data-path and printing system is utilized to improve throughput with large patterns and small address sizes. An advanced 8-pass printing strategy is used to improve error reduction through averaging. `Gridless' printing is accomplished by incorporating grid snap errors from the 8.333 nm address unit size into the CD and placement error budgets. Plate sizes up to 9' X 9' can be accommodated on the new high-speed air-bearing stage. The performance of the system, as measured in factory acceptance testing, is compared to the design specification for critical dimension (CD) control, composite overlay, placement accuracy, stripe butting error, scan linearity, and edge roughness. One major problem encountered in measuring system performance is mask blank quality. With typical mask lithography tool CD performance below 30 nm, CD error contributions above +/- 5 nm from the mask blank become significant components of total CD performance.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brian J. Grenon, D. C. Defibaugh, Donna M. Sprout, Henry Chris Hamaker, and Peter D. Buck "Technical performance of the ALTA-3000 laser writer", Proc. SPIE 2322, 14th Annual BACUS Symposium on Photomask Technology and Management, (7 December 1994);

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