13 March 2018 Multi-wavelength approach towards on-product overlay accuracy and robustness
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Abstract
Success of diffraction-based overlay (DBO) technique1,4,5 in the industry is not just for its good precision and low toolinduced shift, but also for the measurement accuracy2 and robustness that DBO can provide. Significant efforts are put in to capitalize on the potential that DBO has to address measurement accuracy and robustness. Introduction of many measurement wavelength choices (continuous wavelength) in DBO is one of the key new capabilities in this area. Along with the continuous choice of wavelengths, the algorithms (fueled by swing-curve physics) on how to use these wavelengths are of high importance for a robust recipe setup that can avoid the impact from process stack variations (symmetric as well as asymmetric). All these are discussed. Moreover, another aspect of boosting measurement accuracy and robustness is discussed that deploys the capability to combine overlay measurement data from multiple wavelength measurements. The goal is to provide a method to make overlay measurements immune from process stack variations and also to report health KPIs for every measurement. By combining measurements from multiple wavelengths, a final overlay measurement is generated. The results show a significant benefit in accuracy and robustness against process stack variation. These results are supported by both measurement data as well as simulation from many product stacks.
Conference Presentation
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kaustuve Bhattacharyya, Kaustuve Bhattacharyya, Marc Noot, Marc Noot, Hammer Chang, Hammer Chang, Sax Liao, Sax Liao, Ken Chang, Ken Chang, Benny Gosali, Benny Gosali, Eason Su, Eason Su, Cathy Wang, Cathy Wang, Arie den Boef, Arie den Boef, Christophe Fouquet, Christophe Fouquet, Guo-Tsai Huang, Guo-Tsai Huang, Kai-Hsiung Chen, Kai-Hsiung Chen, Kevin Cheng, Kevin Cheng, John Lin, John Lin, "Multi-wavelength approach towards on-product overlay accuracy and robustness", Proc. SPIE 10585, Metrology, Inspection, and Process Control for Microlithography XXXII, 105851F (13 March 2018); doi: 10.1117/12.2297420; https://doi.org/10.1117/12.2297420
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