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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Scatterometry techniques are used to characterize the CD uniformity, focus and dose control, as well as the image contrast of a hyper-NA immersion lithography scanner. Results indicate very good scanner control and stability of these parameters, as well as good precision and sensitivity of the metrology techniques.

This paper examines the extendibility of the scatterometry techniques to characterize structures pushing the limits of current lithographic printing technologies. In particular, we investigate the limits of normal-incidence optical CD (NI-OCD) measurements using the smallest features afforded by the most recent generation of hyper-NA immersion scanners. Special analysis techniques have also been developed and applied to cases relevant to double exposure and double patterning lithography. Models were used successfully to decouple CD and overlay values associated with patterning the first and second set of features on the wafer, using a single scatterometry measurement. These advances pave the way to the development of full solutions for the general case of double patterning structures with two different populations of lines or structures.In addition, the current study focused on seeking a better understanding of the use of scatterometry 3D features characterization, particularly as it relates to OPC model building and verification. The demonstration of tip-to-tip measurements on 3D structures is very encouraging as it introduces the advantages of scatterometry, such as reduced influence of line-edge roughness (LER) and better precision, to the practice of advanced OPC model building.

Applications that require overlay measurement between layers separated by absorbing interlayer films (such as α-carbon) pose significant challenges for sub-50nm processes. In this paper scatterometry methods are investigated as an alternative to meet these stringent overlay metrology requirements. In this article, a spectroscopic Diffraction Based Overlay (DBO) measurement technique is used where registration errors are extracted from specially designed diffraction targets. DBO measurements are performed on detailed set of wafers with varying α-carbon (ACL) thicknesses. The correlation in overlay values between wafers with varying ACL thicknesses will be discussed. The total measurement uncertainty (TMU) requirements for these layers are discussed and the DBO TMU results from sub-50nm samples are reviewed. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 6922 69222W-3 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 6922 69222W-11 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx