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22 March 2008 Evaluating diffraction based overlay metrology for double patterning technologies
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Demanding sub-45 nm node lithographic methodologies such as double patterning (DPT) pose significant challenges for overlay metrology. In this paper, we investigate scatterometry methods as an alternative approach to meet these stringent new metrology requirements. We used a spectroscopic diffraction-based overlay (DBO) measurement technique in which registration errors are extracted from specially designed diffraction targets for double patterning. The results of overlay measurements are compared to traditional bar-in-bar targets. A comparison between DBO measurements and CD-SEM measurements is done to show the correlation between the two approaches. We discuss the total measurement uncertainty (TMU) requirements for sub-45 nm nodes and compare TMU from the different overlay approaches.
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Chandra Saru Saravanan, Yongdong Liu, Prasad Dasari, Oleg Kritsun, Catherine Volkman, Alden Acheta, and Bruno La Fontaine "Evaluating diffraction based overlay metrology for double patterning technologies", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69220C (22 March 2008);

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