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Proceedings Paper

Inspection technique of latent flaws on fine polished glass substrates using stress-induced light scattering method
Author(s): Yoshitaro Sakata; Kazufumi Sakai; Kazuhiro Nonaka
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Paper Abstract

The fine polishing technique, e.g. Chemical Mechanical Polishing treatment (CMP), is one of the most important techniques in the glass substrate manufacturing. However, mechanical interaction, e.g. friction, occurs between the abrasive and the surface of substrates. Therefore, latent flaws are formed in the surfaces of glass substrates depending on the polishing condition. In the case of the cleaning process of the glass substrate in which the latent flaws existed, latent flaws become obvious because glass surfaces were eaten away by chemical interaction of cleaning liquid. Therefore, latent flaws are the cause of decrease the yield of products. In general, non-destructive inspection techniques, e.g. light scattering method, foreign matter on the surface of glass substrates. Though, it is difficult to detect the latent flaws by these method, because these are closed. The present authors propose a novel inspection technique of latent flaws which occurred by the fine polishing technique, using light scattering method with stress concentration (Stress-Induced Light scattering Method; SILSM). SILSM is possible to classify and separately detect latent flaws and particles on the surfaces. Samples are deformed by the actuator and stress concentrations are occurred around the tip of latent flaws. By photo-elastic effect, the refractive index of around the tip of latent flaws is changed. And then, changed refractive index is detected by cooled CCD camera as the light scattering intensity. In this report, applying SILSM to glass substrates, latent flaws on the surface of glass substrates are detected non-destructively, and the usefulness of SILSM is evaluated as novel inspection technique of latent flaws.

Paper Details

Date Published: 1 May 2014
PDF: 8 pages
Proc. SPIE 9132, Optical Micro- and Nanometrology V, 913209 (1 May 2014); doi: 10.1117/12.2052046
Show Author Affiliations
Yoshitaro Sakata, National Institute of Advanced Industrial Science and Technology (Japan)
Kazufumi Sakai, National Institute of Advanced Industrial Science and Technology (Japan)
Kazuhiro Nonaka, National Institute of Advanced Industrial Science and Technology (Japan)

Published in SPIE Proceedings Vol. 9132:
Optical Micro- and Nanometrology V
Christophe Gorecki; Anand Krishna Asundi; Wolfgang Osten, Editor(s)

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