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Proceedings Paper

Manufacturing-induced residual stresses in optical glasses and crystals: Example of residual stress relief by magnetorheological finishing (MRF) in commercial silicon wafers
Author(s): John C. Lambropoulos; Steven R. Arrasmith; Stephen D. Jacobs; Donald Golini
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Paper Abstract

The Twyman effect refers to the generation by grinding of residual compressive stresses on the surface of a brittle material. Two issues are the correlation of stress-induced deformation (bowing) with the compressive force, and the depth over which the compressive stress acts. We summarize results from optical glasses, and we then apply a new analysis to optical crystals, specifically silicon. The issue of grinding-induced stress depth is addressed by demonstrating the relief of lapping-induced stresses in commercial Si wafers by magnetorheological finishing (MRF). MRF is a novel process that is effective for fine figuring and polishing of a variety of optical glasses and crystals. We demonstrate that MRF is suitable for finishing the surfaces of electronic grade single crystal silicon wafers. Four inch diameter <111> silicon wafers were loose abrasive lapped with various sized abrasives. The lapping- induced stress in the wafer surface was extracted by interferometrically measuring the curvature of the wafer due to the Twyman effect. Subsequent polishing by MRF was found to be effective in removing the associated residual stress generated in the wafer surface during loose abrasive lapping. The lapping-induced residual stresses are largest near the lapped surface, decaying with a characteristic length of 0.4-0.5 micrometers into the lapped surface.

Paper Details

Date Published: 27 December 2001
PDF: 10 pages
Proc. SPIE 4451, Optical Manufacturing and Testing IV, (27 December 2001); doi: 10.1117/12.453618
Show Author Affiliations
John C. Lambropoulos, Univ. of Rochester (United States)
Steven R. Arrasmith, Univ. of Rochester (United States)
Stephen D. Jacobs, Univ. of Rochester (United States)
Donald Golini, QED Technologies, LLC (United States)


Published in SPIE Proceedings Vol. 4451:
Optical Manufacturing and Testing IV
H. Philip Stahl, Editor(s)

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