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Proceedings Paper

Photomask CD metrology at the 100-nm node
Author(s): John Allsop; Stephen Johnson; Marcel Demarteau; Onno Wismans
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Paper Abstract

At the 100nm technology node, mask level CDs are typically 400nm with assist features and OPC serifs below 160nm. These design rules represent a severe challenge to conventional optical metrology. The use of any method of measurement, which is not representative of the way the pattern information is transmitted from the mask to the wafer, can lead to measurements that do not correlate directly with those at the wafer (excluding MEEF, magnification factors, lens distortion etc.) The most representative tool for Photomask CD metrology would perhaps be an actinic transmitted light tool. This ideal tool however, may not yet be available. When using alternative non-transmitted measurement, higher resolution is only part of the solution. Matching, calibration and sample interaction must also be considered. This paper discusses the relative merits of optical and non-optical metrology. Multiple, feature specific, gauge R&R studies are used to demonstrate the capability indices, for the Leica LWM250DUV (248nm), at each technology node. Furthermore, the specific application of the optical tool in the measurement of 'assisted' chrome lines, at the 100nm technology node, is demonstrated. The methodology employed includes optical/CDSEM calibration and correlation. Tool specific considerations necessary to achieve a stable and reliable match are detailed

Paper Details

Date Published: 1 August 2002
PDF: 13 pages
Proc. SPIE 4754, Photomask and Next-Generation Lithography Mask Technology IX, (1 August 2002); doi: 10.1117/12.476968
Show Author Affiliations
John Allsop, Photronics (United Kingdom)
Stephen Johnson, Photronics (United Kingdom)
Marcel Demarteau, ASML (Netherlands)
Onno Wismans, ASML (Netherlands)

Published in SPIE Proceedings Vol. 4754:
Photomask and Next-Generation Lithography Mask Technology IX
Hiroichi Kawahira, Editor(s)

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