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20 March 2020 Enabling accurate and robust optical metrology of in device overlay
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Abstract
Utilizing a unique high NA optical system, a new methodology to measure device overlay accurately has been developed with a key differentiation. Historically, optical techniques to measure features below the image resolution require supporting measurement techniques to be used as a reference to anchor the optical measurement. This novel selfreference methodology enables accurate and robust optical metrology for device features after etch eliminating the need for external reference measurements such as Decap, x-sections or high landing energy SEMs. In this paper, we discuss how a high NA Optical Metrology system enables measurements on small area device replica targets, which enables the ability to create a reference target for device measurements. The methodology utilizes this reference target to enable accurate direct on device overlay measurements without the need for an external reference. Furthermore, the technique is expanded to improve the robustness of the measurement and monitor live in production the health of the recipe, ensuring accuracy overtime. This ultimately leads to a method to extend the recipes in real-time based on the health KPIs. The improved accurate and robust device overlay measurements have proven to improve the overlay performance compared to other techniques. This, combined with the speed of optical systems, enables unconstrained dense measurements directly on device structures after etch, allowing for improved overlay control.
© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Min-Seok Kang, Chan Hwang, Seungyoon Lee, Jeongjin Lee, Joon-Soo Park, Christian Leewis, Eun-Ji Yang, Do-Haeng Lee, James Lee, Sabil Huda, Noh-Kyoung Park, Anagnostis Tsiatmas, Giulio Bottegal, Amy Wang, Filippo Belletti, Jan Jitse Venselaar, Giacomo Miceli, Izabela Saj, and Sam Chen "Enabling accurate and robust optical metrology of in device overlay", Proc. SPIE 11325, Metrology, Inspection, and Process Control for Microlithography XXXIV, 1132529 (20 March 2020); https://doi.org/10.1117/12.2553446
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