8 November 2005 Scatterometry based CD and profile metrology of MoSi/quartz structures
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As the on-wafer transistor sizes shrink, and gate nodes run well below 90 nm, it is becoming extremely important to accurately characterize and control the CDs on the Mask. Since Phase shift technology for masks is essential to achieve the geometries of the future, CD and profile metrology on the phase shifting materials becomes critical. Phase shift materials, such as MoSi, present unique challenges for metrology. In this paper, we discuss the effect of the optical properties of MoSi on CD and profile metrology and the challenges in obtaining the correct optical constants needed for accurate metrology. Optical Scatterometry based metrology was used successfully with both Spectroscopic Ellipsometry (SE; λ~ 210nm-1000nm) and Spectroscopic Polarized Reflectometry (Rp; λ: 320nm-780nm). Spectra were collected with Nanometrics' Atlas-M reticle measurement system and were analyzed using ODP software from Timbre Technologies, Inc. Unlike chrome, the optical properties of the MoSi on the grating structure differ significantly from that on the rest of the blanket area of the mask. Unique modeling techniques are required to account for this difference. Etching of the chrome also causes changes in the MoSi top layer that need to be accounted. Data will be presented showing the sensitivities of the CD structures on the mask to variations of Quartz and MoSi optical constants. CD and profile sensitivities to roughness of the MoSi grating structure are also demonstrated.
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Sanjay Yedur, Sanjay Yedur, Vi Vuong, Vi Vuong, Deepak Shivaprasad, Deepak Shivaprasad, T.P. Sarathy, T.P. Sarathy, Milad Tabet, Milad Tabet, Rahul Korlahalli, Rahul Korlahalli, Jiangtao Hu, Jiangtao Hu, } "Scatterometry based CD and profile metrology of MoSi/quartz structures", Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59924I (8 November 2005); doi: 10.1117/12.632304; https://doi.org/10.1117/12.632304

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