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Proceedings Paper

Development of an automated multiple-target mask CD disposition system to enable new sampling strategy
Author(s): Jian Ma; Jeff Farnsworth; Larry Bassist; Ying Cui; Bobby Mammen; Ramaswamy Padmanaban; Venkatesh Nadamuni; Muralidhar Kamath; Ken Buckmann; Julie Neff; Phil Freiberger
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Paper Abstract

Traditional mask critical dimension (CD) disposition systems with only one or two targets is being challenged by the new requirements from mask-users as the wafer process control becomes more complicated in the newer generation of technologies. Historically, the mask shop does not necessarily measure and disposition off the same kind of CD structures that wafer fabs do. Mask disposition specifications and structures come from the frame-design and the tapeout, while wafer-level CD dispositions are mainly based on the historical process window established per CD-skew experiments and EOL (end of line) yield. In the current high volume manufacturing environment, the mask CDs are mainly dispositioned off their mean-to-target (MTT) and uniformity (6sigma) on one or two types of pre-determined structures. The disposition specification is set to ensure the printed mask will meet the design requirements and to ensure minimum deviation from them. The CD data are also used to adjust the dose of the mask exposure tools to control CD MTT. As a result, the mask CD disposition automation system was built to allow only one or two kinds of targets at most. In contrast, wafer-fabs measure a fairly wide range of different structures to ensure their process is on target and in control. The number of such structures that are considered critical is increasing due the growing complexity of the technology. To fully comprehend the wafer-level requirements, it is highly desirable to align the mask CD sample site and disposition to be the same as that of the wafer-fabs, to measure the OPC (optical proximity correction) structures or equivalent whenever possible, and to establish the true correlation between mask CD measurements vs. wafer CD measurement. In this paper, the development of an automated multiple-target mask CD disposition system with the goal of enabling new sampling strategy is presented. The pros and cons of its implementation are discussed. The new system has been inserted in the production of Intel's 65 nm technologies and has become the POR (plan of record) for the future technologies that are being developed.

Paper Details

Date Published: 24 March 2006
PDF: 10 pages
Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 61521K (24 March 2006); doi: 10.1117/12.654326
Show Author Affiliations
Jian Ma, Intel Corp. (United States)
Jeff Farnsworth, Intel Corp. (United States)
Larry Bassist, Intel Corp. (United States)
Ying Cui, Intel Corp. (United States)
Bobby Mammen, Intel Corp. (United States)
Ramaswamy Padmanaban, Intel Corp. (United States)
Venkatesh Nadamuni, Intel Corp. (United States)
Muralidhar Kamath, Intel Corp. (United States)
Ken Buckmann, Intel Corp. (United States)
Julie Neff, Intel Corp. (United States)
Phil Freiberger, Intel Corp. (United States)

Published in SPIE Proceedings Vol. 6152:
Metrology, Inspection, and Process Control for Microlithography XX
Chas N. Archie, Editor(s)

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