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Proceedings Paper

Reducing the overlay metrology sensitivity to perturbations of the measurement stack
Author(s): Yue Zhou; DeNeil Park; Karsten Gutjahr; Abhishek Gottipati; Tam Vuong; Sung Yong Bae; Nicholas Stokes; Aiqin Jiang; Po Ya Hsu; Mark O'Mahony; Andrea Donini; Bart Visser; Chris de Ruiter; Grzegorz Grzela; Hans van der Laan; Martin Jak; Pavel Izikson; Stephen Morgan
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Paper Abstract

Overlay metrology setup today faces a continuously changing landscape of process steps. During Diffraction Based Overlay (DBO) metrology setup, many different metrology target designs are evaluated in order to cover the full process window. The standard method for overlay metrology setup consists of single-wafer optimization in which the performance of all available metrology targets is evaluated. Without the availability of external reference data or multiwafer measurements it is hard to predict the metrology accuracy and robustness against process variations which naturally occur from wafer-to-wafer and lot-to-lot. In this paper, the capabilities of the Holistic Metrology Qualification (HMQ) setup flow are outlined, in particular with respect to overlay metrology accuracy and process robustness. The significance of robustness and its impact on overlay measurements is discussed using multiple examples. Measurement differences caused by slight stack variations across the target area, called grating imbalance, are shown to cause significant errors in the overlay calculation in case the recipe and target have not been selected properly. To this point, an overlay sensitivity check on perturbations of the measurement stack is presented for improvement of the overlay metrology setup flow. An extensive analysis on Key Performance Indicators (KPIs) from HMQ recipe optimization is performed on µDBO measurements of product wafers. The key parameters describing the sensitivity to perturbations of the measurement stack are based on an intra-target analysis. Using advanced image analysis, which is only possible for image plane detection of μDBO instead of pupil plane detection of DBO, the process robustness performance of a recipe can be determined. Intra-target analysis can be applied for a wide range of applications, independent of layers and devices.

Paper Details

Date Published: 28 March 2017
PDF: 12 pages
Proc. SPIE 10145, Metrology, Inspection, and Process Control for Microlithography XXXI, 101452G (28 March 2017); doi: 10.1117/12.2257913
Show Author Affiliations
Yue Zhou, GLOBALFOUNDRIES Inc. (United States)
DeNeil Park, GLOBALFOUNDRIES Inc. (United States)
Karsten Gutjahr, GLOBALFOUNDRIES Inc. (United States)
Abhishek Gottipati, GLOBALFOUNDRIES Inc. (United States)
Tam Vuong, GLOBALFOUNDRIES Inc. (United States)
Sung Yong Bae, GLOBALFOUNDRIES Inc. (United States)
Nicholas Stokes, GLOBALFOUNDRIES Inc. (United States)
Aiqin Jiang, ASML US, Inc. (United States)
Po Ya Hsu, ASML US, Inc. (United States)
Mark O'Mahony, ASML US, Inc. (United States)
Andrea Donini, ASML Netherlands B.V. (Netherlands)
Bart Visser, ASML Netherlands B.V. (Netherlands)
Chris de Ruiter, ASML Netherlands B.V. (Netherlands)
Grzegorz Grzela, ASML Netherlands B.V. (Netherlands)
Hans van der Laan, ASML Netherlands B.V. (Netherlands)
Martin Jak, ASML Netherlands B.V. (Netherlands)
Pavel Izikson, ASML Netherlands B.V. (Netherlands)
Stephen Morgan, ASML Netherlands B.V. (Netherlands)

Published in SPIE Proceedings Vol. 10145:
Metrology, Inspection, and Process Control for Microlithography XXXI
Martha I. Sanchez, Editor(s)

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