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Proximity matching is a common activity in the wafer fabs1,2,3for purposes such as process transfer, capacity expansion, improved scanner yield and fab productivity. The requirements on matching accuracy also become more and more stringent as CD error budget shrinks with the feature size as technology advances. Various studies have been carried out, using scanner knobs including NA, inner sigma, outer sigma, stage tilt, ellipticity, and dose. In this paper, we present matching results for critical features of a logic device, between an ASML XT:19x0i scanner and an XT:1700i (reference), demonstrating the advantage of freeform illuminator pupil as part of the adjustable knobs to provide additional flexibility. We also present the investigation of a novel method using lens manipulators for proximity matching, effectively injecting scalar wavefront to an XT:19x0i to mimic the behavior of the XT:1700i lens.

Scanner mismatch has become one of the critical issues in high volume memory production. There are several components that contribute to the scanner CD mismatch. One of the major components is illumination pupil difference between scanners. Because of acceleration of dimensional shrinking in memory devices, the CD mismatch became more critical in electrical performance and process window. In this work, we demonstrated computational lithography model based scanner matching for sub 3x nm memory devices. We used ASML XT:1900Gi as a reference scanner and ASML NXT:1950i as the to-be-matched scanner. Wafer metrology data and scanner specific parameters are used to build a computational model, and determine the optimal settings by model simulation to minimize the CD difference between scanners. Nano Geometry Research (NGR) was used as a wafer CD metrology tool for both model calibration and matching result verification. The extracted pupil parameters from measured source map from both before and after matching are inspected and analyzed. Simulated and measured process window changes by applying the matching sub-recipe are also evaluated.