12 April 2013 High order field-to-field corrections for imaging and overlay to achieve sub 20-nm lithography requirements
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Immersion lithography is being extended to the 20-nm and 14-nm node and the lithography performance requirements need to be tightened further to enable this shrink. In this paper we present an integral method to enable high-order fieldto- field corrections for both imaging and overlay, and we show that this method improves the performance with 20% - 50%. The lithography architecture we build for these higher order corrections connects the dynamic scanner actuators with the angle resolved scatterometer via a separate application server. Improvements of CD uniformity are based on enabling the use of freeform intra-field dose actuator and field-to-field control of focus. The feedback control loop uses CD and focus targets placed on the production mask. For the overlay metrology we use small in-die diffraction based overlay targets. Improvements of overlay are based on using the high order intra-field correction actuators on a field-tofield basis. We use this to reduce the machine matching error, extending the heating control and extending the correction capability for process induced errors.
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Jan Mulkens, Jan Mulkens, Michael Kubis, Michael Kubis, Paul Hinnen, Paul Hinnen, Roelof de Graaf, Roelof de Graaf, Hans van der Laan, Hans van der Laan, Alexander Padiy, Alexander Padiy, Boris Menchtchikov, Boris Menchtchikov, } "High order field-to-field corrections for imaging and overlay to achieve sub 20-nm lithography requirements", Proc. SPIE 8683, Optical Microlithography XXVI, 86831J (12 April 2013); doi: 10.1117/12.2011550; https://doi.org/10.1117/12.2011550

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