25 March 2008 Novel approach for immersion lithography defectivity control to increase productivity
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Abstract
Increase of Depth of Focus (DOF) and higher Numerical Aperture (NA), make of immersion lithography a sub-50nm technology node enabler. At the same time it introduces a range of new defect types, also known as immersion defects. According to the ITRS roadmap, the Smallest Defect Of Interest (SDOI) for the 45nm node has a size of 30nm [1] which is the minimal defect size which poses risk to the integrity of the post litho chain processes. A novel approach of Immersion Defectivity Baseline creation and monitoring has been developed for the 45nm technology node by ASML, supported by Applied Materials. An Immersion Defectivity Baseline consists of: a qualified stack, a dedicated defectivity reticle, a Defect Inspection Tool with an optimized inspection recipe, a Defect Review SEM with an optimized defect review recipe and a defect qualification scheme. The new approach to Immersion Defectivity Baseline creation is based on the combined capabilities of highest resolution bright-field inspection and SEM (Scanning Electron Microscopy) review that are available today, with a unique qualification methodology using printed programmed defects that cover the full printable size range. The inspection tool's SDOI detection sensitivity has been optimized for engineering, production as well as monitoring modes, with negligible nuisance rate and basic classification capability followed by highly accurate SEM review and classification. As a result, it enables a stringently controlled, highly efficient, automated defect classification for baseline monitoring and increased productivity. The SEM material analysis sub-apparatus complete the control loop for baseline creation and excursion control. This paper presents a protocol for Immersion Defectivity Baseline creation and control methodologies used for the latest ASML immersion scanner.
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Ilan Englard, Raf Stegen, Peter Vanoppen, Ingrid Minnaert-Janssen, Ted der Kinderen, Erik van Brederode, Frank Duray, Jeroen Linders, Denis Ovchinnikov, Rich Piech, Claudio Masia, Noam Hillel, Erez Ravid, Ofer Rotlevi, Amir Wilde, Saar Shabtay, Zach Telor, Robert Schreutelkamp, "Novel approach for immersion lithography defectivity control to increase productivity", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69223U (25 March 2008); doi: 10.1117/12.776085; https://doi.org/10.1117/12.776085
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