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Proceedings Paper

Impact of chuck flatness on wafer distortion and stepper overlay
Author(s): Klaus Simon; H.-U. Scheunemann; Hans L. Huber; F. Gabeli
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Paper Abstract

Overlay accuracy is known as one of the most important subjects for ULSI device production. Significant contributions such as alignment accuracy and mask distortions are well known. By breaking the 100 nm range on overlay accuracy a number of influences have to take into account, which were usually neglected for relaxed design rules. One of these influences to the overlay is directly related to wafer distortions induced by flatness deviations of wafer chucks. This impact was characterized by investigating the elastic behavior of 4' wafers (525 micrometers thick), fixed on a wafer chuck. Induced elastical deformation due to flatness error of the chuck causes strains and elongations in the wafer surface and therefore wafer distortions. The results obtained by exposure experiments and calculations show that even a point size defect has a 30 mm spreading. Therefore the induced distortions arrives about 100 nm in case of a 3 micrometers flatness irregularity. The final result of the investigations induces that the flatness differences between different wafer chucks or steppers should be smaller than 1 micrometers for design rules below quarter micron.

Paper Details

Date Published: 24 June 1993
PDF: 8 pages
Proc. SPIE 1924, Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing III, (24 June 1993); doi: 10.1117/12.146510
Show Author Affiliations
Klaus Simon, Fraunhofer-Institut fuer Mikrostrukturtechnik (Germany)
H.-U. Scheunemann, Fraunhofer-Institut fuer Mikrostrukturtechnik (Germany)
Hans L. Huber, Fraunhofer-Institut fuer Mikrostrukturtechnik (Germany)
F. Gabeli, Karl Suess GmbH & Co. (Germany)

Published in SPIE Proceedings Vol. 1924:
Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing III
David O. Patterson, Editor(s)

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