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Proceedings Paper

A study of hot spot measurement on WLCD
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Paper Abstract

Optical lithography stays at 193nm with a numerical aperture of 1.35 for several more years before moving to EUV lithography. Utilization of 193nm lithography for 45nm and beyond forces the mask shop to produce complex mask designs and tighter lithography specifications which in turn make process control more important than ever. High yield with regards to chip production requires accurate process control. Critical Dimension Uniformity (CDU) is one of the key parameters necessary to assure good performance and reliable functionality of any integrated circuit. There are different contributors which impact the total wafer CDU, mask CD uniformity, resist process, scanner and lens fingerprint, wafer topography, etc. In this paper, the wafer level CD metrology tool WLCD of Carl Zeiss SMS is utilized for CDU measurements in conjunction with the CDC tool from Carl Zeiss SMS which provides CD uniformity correction. The WLCD measures CD based on proven aerial imaging technology. The CDC utilizes an ultrafast femto-second laser to write intra-volume shading elements (Shade-In ElementsTM) inside the bulk material of the mask. By adjusting the density of the shading elements, the light transmission through the mask is locally changed in a manner that improves wafer CDU when the corrected mask is printed. The objective of this study is to evaluate the usage of these two tools in a closed loop process to optimize CDU of the mask before leaving the mask shop and to ensure improved intra-field CDU at wafer level. Mainly we present the method of operation and results for logic pattering by using these two tools.

Paper Details

Date Published: 29 June 2012
PDF: 9 pages
Proc. SPIE 8441, Photomask and Next-Generation Lithography Mask Technology XIX, 844107 (29 June 2012); doi: 10.1117/12.978706
Show Author Affiliations
Hidemichi Imai, Dai Nippon Printing Co., Ltd. (Japan)
Shingo Yoshikawa, Dai Nippon Printing Co., Ltd. (Japan)
Hideyoshi Takamizawa, Dai Nippon Printing Co., Ltd. (Japan)
Ute Buttgereit, Carl Zeiss SMS GmbH (Germany)
Thomas Thaler, Carl Zeiss SMS GmbH (Germany)

Published in SPIE Proceedings Vol. 8441:
Photomask and Next-Generation Lithography Mask Technology XIX
Kokoro Kato, Editor(s)

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