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Journal of Micro/Nanolithography, MEMS, and MOEMS

Particle contamination effects in extreme ultraviolet lithography: enhanced theory for the analytical determination of critical particle sizes
Author(s): Gerd Brandstetter; Sanjay Govindjee
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Paper Abstract

Existing analytical and numerical methodologies are discussed and then extended in order to calculate critical contamination-particle sizes, which will result in deleterious effects during extreme ultraviolet lithography E-chucking in the face of an error budget on the image-placement-error (IPE). The enhanced analytical models include a gap-dependent clamping pressure formulation, the consideration of a general material law for realistic particle crushing and the influence of frictional contact. We present a discussion of the defects of the classical de-coupled modeling approach where particle crushing and mask/chuck-indentation are separated from the global computation of mask bending. To repair this defect we present a new analytic approach based on an exact Hankel transform method which allows a fully coupled solution. This will capture the contribution of the mask-indentation to the image-placement-error (estimated IPE increase of 20%). A fully coupled finite element model is used to validate the analytical models and to further investigate the impact of a mask back-side CrN-layer. The models are applied to existing experimental data with good agreement. For a standard material combination, a given IPE tolerance of 1 nm and a 15 kPa closing pressure, we derive bounds for single particles of cylindrical shape (radius×height<44  μm2) and spherical shape (diameter<12  μm).

Paper Details

Date Published: 13 June 2012
PDF: 9 pages
J. Micro/Nanolith. 11(2) 023011 doi: 10.1117/1.JMM.11.2.023011
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 11, Issue 2
Show Author Affiliations
Gerd Brandstetter, Univ. of California, Berkeley (United States)
Sanjay Govindjee, Univ. of California, Berkeley (United States)

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