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Publication Citation: Calibrated Overlay Wafer Standard

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Author(s): Michael T. Stocker; Richard M. Silver; Ravikiran Attota; Jay S. Jun;
Title: Calibrated Overlay Wafer Standard
Published: January 01, 2007
Abstract: This document describes the physical characteristics of Standard Reference Material SRM 5000, provides guidance for its use in calibrating overlay (OL) tools, and gives information and precautions concerning its care and handling.Standard Reference Material SRM 5000 was developed for use in calibrating OL tools.  It is a double-etched silicon on silicon 200 mm wafer with various OL targets.  Five Frame-in-Frame targets and five Bar-in-Bar targets on this wafer were calibrated.  This SRM makes possible traceable OL measurements in a customer s facility in effect by comparisons of measurements on this wafer to the certified values provided by the National Institute of Standards and Technology (NIST).A layout of the wafer is presented to guide the user to the locations that contain the calibrated OL targets.  A discussion on calibration strategies is included to help the user decide on the best way to use the SRM 5000.  The NIST OL tool and certification technique are described.  The statistical performance of the system was evaluated by monitoring values from a control wafer.  The factors which contribute to the calibration uncertainty are explained and evaluated.
Citation: NIST SP - 260-165
Keywords: accuracy;bar-in-bar;frame-in-frame;measurement uncertainty;optical microscope;overlay;standard reference material
Research Areas: Metrology, Manufacturing