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Indexed by:期刊论文

Date of Publication:2016-10-01

Journal:PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY

Included Journals:SCIE、EI、Scopus

Volume:46

Page Number:339-348

ISSN No.:0141-6359

Key Words:Three-point-support method; Position determination; Gravity-induced deflection; Large and thin panels

Abstract:The flatness measurement of large and thin wafers is affected greatly by gravity. Inverting method is often used to cancel the effect. However, it is required that the positions of the supports and wafers are perfectly symmetric about the inversion axis. In this study a three-point-support method based on position determination of supports and wafers was proposed. The supporting balls and the wafer were placed in arbitrary positions and their positions were obtained by measurement and fed into the FEM model which was developed to calculate the gravity-induced deflection (GID). The methods to acquire the positions of the supports and the wafer were proposed. The position measurement accuracy of the supports was improved greatly by circle fitting to the profile of the supporting ball. Wafer edge point was obtained accurately as the intersection point between the wafer surface line and the edge profile. The method to measure the wafer thickness using only one displacement sensor on the same equipment was presented. The simulation results were verified by experimental results. The centering device for the wafer and the positioning accuracy requirements of the supports are not needed any more. The effect of the positions of the supports and the wafer was reduced to be less than 1 mu m for a 300 mu m diameter and 397 mu m thickness wafer with GID over 140 mu m. This method could also be used for accurate flatness measurement of other large and thin panels. (C) 2016 Elsevier Inc. All rights reserved.