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Proceedings Paper

High sensitivity electric field monitoring system for control of field-induced CD degradation in reticles (EFM)
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Paper Abstract

It has recently been reported [1] that production reticles are subject to progressive CD degradation during use and intense study is under way to try and identify the causes of it. One damage mechanism which has already been identified and quantified [2] is electric field induced migration of chrome (EFM). This can be caused by electric fields that are more than 100x weaker than those that cause ESD. Such low level electric fields can be experienced by a reticle during normal handling and processing steps, as well as coming from external sources during transportation and storage. The field strength of concern is lower than most electrostatic field meters are designed to measure and it can be difficult or impossible to measure such fields inside the cramped environment of equipment. To measure this risk a new sensor device ("E-Reticle") has been developed having the same materials of construction and form factor as a standard chrome-on-quartz reticle. It allows the electric field that a reticle would experience during normal use and handling to be measured and recorded. Results from testing of this device in a semiconductor production facility are reported, showing that certain processes like reticle washing are inherently hazardous. It also enables identification of problems with electrostatic protection measures inside equipment, such as unbalanced ionizers or poor load port grounding. The device is shown to be capable of recording electric fields in the reticle handling environment that are below the recommended maximum that is being proposed for the 2009 ITRS guidelines.

Paper Details

Date Published: 11 May 2009
PDF: 10 pages
Proc. SPIE 7379, Photomask and Next-Generation Lithography Mask Technology XVI, 73791P (11 May 2009); doi: 10.1117/12.824302
Show Author Affiliations
Thomas Sebald, ESTION GmbH & Co. KG (Germany)
Gavin Rider, Microtome, Inc. (United States)

Published in SPIE Proceedings Vol. 7379:
Photomask and Next-Generation Lithography Mask Technology XVI
Kunihiro Hosono, Editor(s)

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