Paper
2 April 2014 Improvement of inter-field CDU by using on-product focus control
Author Affiliations +
Abstract
This paper introduces to improve inter-field CDU with on-product focus control by diffraction based focus (DBF) method. For DBF target selection, a robust focus metrology for focus control was obtained, and the selected DBF target was integrated on each seven spot of a product reticle. For on-product focus control, previously on-product focus monitoring was performed, and the monitored lots showed a stable focus fingerprint. Based on the result, Z and Z/ Rx/Ry corrections per field on wafers were applied. Focus uniformity of controlled wafers was improved up to 29% in comparison with non-corrected ones. To demonstrate the improvement of inter-field CDU, Full CDs on wafers were measured by SEM. As a result, inter-field CDU for controlled wafers was improved by 16% (3σ) compared with noncontrolled wafers.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kyeong Dong Park, Tony Park, Jong Hyun Hwang, Jin Phil Choi, and Young Seog Kang "Improvement of inter-field CDU by using on-product focus control", Proc. SPIE 9050, Metrology, Inspection, and Process Control for Microlithography XXVIII, 90500R (2 April 2014); https://doi.org/10.1117/12.2046224
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CITATIONS
Cited by 3 scholarly publications.
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KEYWORDS
Semiconducting wafers

Metrology

Reticles

Signal processing

Control systems

Lithography

Process control

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