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Journal of Micro/Nanolithography, MEMS, and MOEMS • Open Access

Role of wafer geometry in wafer chucking
Author(s): Kevin T. Turner; Roshita Ramkhalawon; Jaydeep K. Sinha

Paper Abstract

Wafer chucks are used in advanced lithography systems to hold and flatten wafers during exposure. To minimize defocus and overlay errors, it is important that the chuck provide sufficient pressure to completely chuck the wafer and remove flatness variations across a broad range of spatial wavelengths. Analytical and finite element models of the clamping process are presented here to understand the range of wafer geometry features that can be fully chucked with different clamping pressures. The analytical model provides a simple relationship to determine the maximum feature amplitude that can be chucked as a function of spatial wavelength and chucking pressure. Three-dimensional finite element simulations are used to examine the chucking of wafers with various geometries, including cases with simulated and measured shapes. The analytical and finite element results both demonstrate that geometry variations with short spatial wavelengths (e.g., high-frequency wafer shape features) present the greatest challenge to achieving complete chucking. The models and results presented here can be used to provide guidance on wafer geometry and chuck designs for advanced exposure tools.

Paper Details

Date Published: 22 May 2013
PDF: 14 pages
J. Micro/Nanolith. MEMS MOEMS 12(2) 023007 doi: 10.1117/1.JMM.12.2.023007
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 12, Issue 2
Show Author Affiliations
Kevin T. Turner, Univ. of Pennsylvania (United States)
Roshita Ramkhalawon, KLA-Tencor Corp. (United States)
Jaydeep K. Sinha, KLA-Tencor Corp. (United States)

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