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26 July 1999 CD uniformity consideration for DUV step and scan tools
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In this paper, we evaluate the CD-uniformity performance of an advanced DUV step and scan exposure tool. Using high quality reticles CD-uniformity at semi-dense lines is shown to be less than 10nm at best focus and less than 20nm at 0.6 micrometers focus range. Isolated lines show 10nm CD-uniformity at best focus and 20nm at 0.4 micrometers focus range. Removing reticle contribution leads to a decreases of intra-field CD- uniformity up to 6nm. At 0.18 micrometers lines, 0.45 micrometers pitch we found that the Mask Error Factor (MEF) is around 1. Going to smaller feature sizes and/or defocus MEF increases rapidly. We show that proper focus control is crucial for isolated line intra-field CD-control. Horizontal and vertical lines behave very similarly at semi-dense pitch. The isolated horizontal lines show a considerably higher DOF and tighter intra-field CD-control than isolated vertical lines. We are able to show both reticle and scanner contributions are not a limiting factor for fulfilling the requirements for CD-control of state of the art microprocessors. In case of 0.15micrometers linewidth and/or smaller pitches mask eros become more critical due to a considerable increase of the MEF.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rolf Seltmann, Anna Maria Minvielle, Chris A. Spence, Sven Muehle, Luigi Capodieci, and Khanh B. Nguyen "CD uniformity consideration for DUV step and scan tools", Proc. SPIE 3679, Optical Microlithography XII, (26 July 1999);


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