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Proceedings Paper

Wafer level CD metrology on photomasks using aerial imaging technology
Author(s): Thomas Scherübl; Ulrich Strößner; Holger Seitz; Robert Birkner; Rigo Richter
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Paper Abstract

Recently more and more mask designs for critical layers involve strong OPC which increases the complexity for standard CD SEM mask measurements and conclusive interpretation of results. For wafer printing the wafer level CD is the crucial measure if the mask can be successfully used in production. Recent developments in the AIMSTM software have enabled the user to use the tool for wafer level CD metrology under scanner conditions. The advantage of this methodology is that AIMSTM does see the CD with scanner eyes. All lithographic relevant effects like OPC imaging which can not be measured by other tools like mask CD SEM will be captured optically by the AIMSTM principle. Therefore, measuring the CD uniformity of the mask by using AIMSTM will lead to added value in mask metrology. With decreasing feature sizes the requirements for CD metrology do increase. In this feasibility study a new prototype algorithm for measuring the lithographically relevant AIMSTM CD with sub pixel accuracy has been tested. It will be demonstrated that by using this algorithm line edge and line width roughness can be measured accurately by an AIMSTM image. Furthermore, CD repeatability and tool matching results will be shown.

Paper Details

Date Published: 19 May 2008
PDF: 8 pages
Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 70282W (19 May 2008); doi: 10.1117/12.793102
Show Author Affiliations
Thomas Scherübl, Carl Zeiss SMS GmbH (Germany)
Ulrich Strößner, Carl Zeiss SMS GmbH (Germany)
Holger Seitz, Carl Zeiss SMS GmbH (Germany)
Robert Birkner, Carl Zeiss SMS GmbH (Germany)
Rigo Richter, Carl Zeiss SMS GmbH (Germany)

Published in SPIE Proceedings Vol. 7028:
Photomask and Next-Generation Lithography Mask Technology XV
Toshiyuki Horiuchi, Editor(s)

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