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Proceedings Paper

Reducing the impact of reticle CD-non-uniformity of multiple structures by dose corrections based on aerial image measurements
Author(s): Ute Buttgereit; Robert Birkner; Thomas Scheruebl; Sander de Putter; Bernardo Kastrup; Jo Finders
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Paper Abstract

For many critical lithography applications the main contributor to wafer intra-field CD variation is the reticle CD variation. Current practice is that the input data needed to correct the effect of the reticle on the wafer CD is gathered using wafer exposures and SEM or scatterometry analysis. This approach consumes valuable scanner time and adds wafer costs. In this work we evaluate the potential for Intra-Field CD non-uniformity (CDU) correction based on aerial image reticle measurements for a complex 2D structure, including peripheral structures. The application selected is a 45nm rotated brick wall structure (active area DRAM). A total of 10 line / space structures (both horizontal and vertical) through pitch represent the periphery. Mask qualification has been performed using the newly developed Zeiss WLCD32 metrology tool, which measures wafer level CD on masks using aerial imaging technology. Excellent correlation is shown between intra-field wafer data and WLCD32 data. Furthermore, a comparison is made between the correction potential of ASML DoseMapper recipes based on wafer data and on WLCD32 mask data, indicating that the potential CDU improvement via both approaches is similar. Exposures with the resulting dose recipes have been used to confirm this predicted correction potential in a realistic setting.

Paper Details

Date Published: 2 April 2010
PDF: 12 pages
Proc. SPIE 7638, Metrology, Inspection, and Process Control for Microlithography XXIV, 76380D (2 April 2010); doi: 10.1117/12.848053
Show Author Affiliations
Ute Buttgereit, Carl Zeiss SMS GmbH (Germany)
Robert Birkner, Carl Zeiss SMS GmbH (Germany)
Thomas Scheruebl, Carl Zeiss SMS GmbH (Germany)
Sander de Putter, ASML Netherlands B.V. (Netherlands)
Bernardo Kastrup, ASML Netherlands B.V. (Netherlands)
Jo Finders, ASML Netherlands B.V. (Netherlands)

Published in SPIE Proceedings Vol. 7638:
Metrology, Inspection, and Process Control for Microlithography XXIV
Christopher J. Raymond, Editor(s)

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