Simulations of a SCALPEL wafer-heating correction using an adaptive Kalman filter

Stuart T. Stanton

doi:10.1117/12.436644

20 August 2001 Simulations of a SCALPEL wafer-heating correction using an adaptive Kalman filter

Stuart T. Stanton

Proceedings Volume 4343, Emerging Lithographic Technologies V; (2001) https://doi.org/10.1117/12.436644
Event: 26th Annual International Symposium on Microlithography, 2001, Santa Clara, CA, United States

Abstract

The high-energy (100KeV) electron imaging process used by SCALPEL causes a dynamic heat load and wafer expansion response. Despite good thermal contact between the wafer and chuck, the dynamic distortion on a die length scale is too large to allow in the overlay error budget, and is fundamentally difficult to prevent or dissipate. However, the sub-field scanning strategy of SCALPEL allows us to implement a dynamic distortion-correction algorithm, by making a real-time position adjustment of the imaging sub-field. Analytical tools developed for understanding these phenomena could be applied in a purely predictive correction algorithm, in principle. However, these predictions are limited by the variability of chuck thermal contact, as well as by difficulty in handling the frictional chuck-attachment boundary condition. Hence, a means of improving upon a basic prediction is necessary to support a robust correction strategy. In this paper, I will explore the practical real-time implementation of a correction algorithm based on Adaptive Kalman Filter techniques, using dynamic alignment updates. Simulations demonstrate the feasibility of this approach to make a very close estimate of the ideal correction.

Citation Download Citation

Stuart T. Stanton "Simulations of a SCALPEL wafer-heating correction using an adaptive Kalman filter", Proc. SPIE 4343, Emerging Lithographic Technologies V, (20 August 2001); https://doi.org/10.1117/12.436644

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