Aberration measurement and matching: a correlation of measurement techniques and dedication scheme implications

Roberts, W.; Jekauc, Igor

doi:10.1117/12.535288

Cited by 1 publication

(1 citation statement)

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“…Image placement error can be used as a metric for tool-to-tool matching in a process environment to minimize the intrafield overlay of different product layers. 10 The dependency of the image placement error on pattern, illumination type, and field position makes the error difficult to compensate. Moreover, layer-to-layer overlay corrections are often calculated after measuring typical barin-bar overlay patterns.…”

Section: Introductionmentioning

confidence: 99%

Image placement error: closing the gap between overlay and imaging

Hendrickx

Colina

Hoff

et al. 2005

J. Micro/Nanolith. MEMS MOEMS

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We perform experimental and theoretical studies of image placement error induced by aberrations of the projection lens. The goal is to experimentally determine the magnitude of the image placement errors, to compare experiments and simulations, and to screen possible correction strategies. The calculations and experiments are done for ArF lithography. Theoretically, we simulate image placement error using the projection lens aberration data and simulators such as Prolith or Solid-C. Features with low and high sensitivities to lens aberrations are identified, together with a reference feature that has low sensitivity for image placement error. Dedicated reticles are fabricated to print various features at different illumination conditions on the same substrate. The resulting patterns could be analyzed using top-down scanning electron microscopy ͑SEM͒, but also optically with the standard optical overlay tool KLA5200. For both techniques, the experimentally found image placement errors are in excellent agreement with simulations. In simulations, we calculate the dependency of the image placement error on pattern density, pattern orientation, and illumination conditions. These tendencies are experimentally reproduced. We conclude with a case study that demonstrates a possible correction strategy for image placement error.

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Section: Introductionmentioning

confidence: 99%