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Proceedings Paper

Improving focus performance at litho using diffraction-based focus metrology, novel calibration methods, interface, and control loop
Author(s): Jiarui Hu; Y. L. Chen; K. H. Chen; Brian Lee; Frankie Tsai; C. M. Ke; C. H. Liao; Desmond Ngo; Benny Gosali; Robin Tijssen; Vincent Huang; Ward Tu; Marc Noot; Maryana Escalante Marun; Christian Leewis; Carlo Luijten; Frank Staals; Martijn Van Veen; Francois Furthner; Stuart Young; Kaustuve Bhattacharyya
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Paper Abstract

In advanced optical lithography the requirements of focus control continues to tighten. Usable depth of focus (DoF) is already quite low due to typical sources of focus errors, such as topography, wafer warpage and the thickness of photoresist. And now the usable DoF is further decreased by hotspots (design and imaging hotspots). All these have put extra challenges to improve focus metrology, scanner focus stability calibrations and on-product correction mechanisms.

Asymmetric focus targets are developed to address robustness in focus measurements using diffraction-based focus (DBF and μDBF) metrology. A new layout specific calibration methodology is introduced for baseline focus setup and control in order to improve scanner focus uniformity and stability using the measurements of the above mentioned asymmetric targets. A similar metrology is also used for on product focus measurements. Moreover, a few novel alternative methods are also investigated for on-product focus measurements.

Data shows good correlation between DBF and process on record (POR) method using traditional FEM. The new focus calibration demonstrated robustness, stability and speed. This technical publication will report the data from all the above activities including results from various product layers.

Paper Details

Date Published: 8 March 2016
PDF: 5 pages
Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 977829 (8 March 2016); doi: 10.1117/12.2220373
Show Author Affiliations
Jiarui Hu, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
Y. L. Chen, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
K. H. Chen, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
Brian Lee, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
Frankie Tsai, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
C. M. Ke, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
C. H. Liao, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
Desmond Ngo, ASML (Taiwan)
Benny Gosali, ASML (Taiwan)
Robin Tijssen, ASML (Netherlands)
Vincent Huang, ASML (Taiwan)
Ward Tu, ASML (Taiwan)
Marc Noot, ASML (Netherlands)
Maryana Escalante Marun, ASML (Netherlands)
Christian Leewis, ASML (Netherlands)
Carlo Luijten, ASML (United States)
Frank Staals, ASML (Netherlands)
Martijn Van Veen, ASML (Netherlands)
Francois Furthner, ASML (Netherlands)
Stuart Young, ASML (Netherlands)
Kaustuve Bhattacharyya, ASML (Netherlands)


Published in SPIE Proceedings Vol. 9778:
Metrology, Inspection, and Process Control for Microlithography XXX
Martha I. Sanchez, Editor(s)

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