3 March 2010 Improving aberration control with application specific optimization using computational lithography
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As the industry drives to lower k1 imaging we commonly accept the use of higher NA imaging and advanced illumination conditions. The advent of this technology shift has given rise to very exotic pupil spread functions that have some areas of high thermal energy density creating new modeling and control challenges. Modern scanners are equipped with advanced lens manipulators that introduce controlled adjustments of the lens elements to counteract the lens aberrations existing in the system. However, there are some specific non-correctable aberration modes that are detrimental to important structures. In this paper, we introduce a methodology for minimizing the impact of aberrations for specific designs at hand. We employ computational lithography to analyze the design being imaged, and then devise a lens manipulator control scheme aimed at optimizing the aberration level for the specific design. The optimization scheme does not minimize the overall aberration, but directs the aberration control to optimize the imaging performance, such as CD control or process window, for the target design. Through computational lithography, we can identify the aberration modes that are most detrimental to the design, and also correlations between imaging responses of independent aberration modes. Then an optimization algorithm is applied to determine how to use the lens manipulators to drive the aberrations modes to levels that are best for the specified imaging performance metric achievable with the tool. We show an example where this method is applied to an aggressive memory device imaged with an advanced ArF scanner. We demonstrate with both simulation and experimental data that this application specific tool optimization successfully compensated for the thermal induced aberrations dynamically, improving the imaging performance consistently through the lot.
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Jianming Zhou, Jianming Zhou, Youping Zhang, Youping Zhang, Peter Engblom, Peter Engblom, Mike Hyatt, Mike Hyatt, Eric Wu, Eric Wu, Martin Snajdr, Martin Snajdr, Anton deVilliers, Anton deVilliers, Yuan He, Yuan He, Craig Hickman, Craig Hickman, Peng Liu, Peng Liu, Dennis de Lang, Dennis de Lang, Bernd Geh, Bernd Geh, Erik Byers, Erik Byers, Scott Light, Scott Light, } "Improving aberration control with application specific optimization using computational lithography", Proc. SPIE 7640, Optical Microlithography XXIII, 76400K (3 March 2010); doi: 10.1117/12.846697; https://doi.org/10.1117/12.846697

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