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19 March 2015 Scanner focus metrology for advanced node scanner monitoring and control
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Scanner Focus window of the lithographic process becomes much smaller due to the shrink of the device node and multipatterning approach. Consequently, the required performance of scanner focus becomes tighter and more complicated. Focus control/monitoring methods such as “field-by-field focus control” or “intra-field focus control” is a necessity. Moreover, tight scanner focus performance requirement starts to raise another fundamental question: accuracy of the reported scanner focus.

The insufficient accuracy of the reported scanner focus using the existing methods originates from:

a) Focus measurement quality, which is due to low sensitivity of measured targets, especially around the nominal production focus.

b) The scanner focus is estimated using special targets, e.g. large pitch target and not using the device-like structures (irremovable aberration impact).

Both of these factors are eliminated using KLA-Tencor proprietary “Focus Offset” technology.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jimyung Kim, Youngsik Park, Taehwa Jeong, Suhyun Kim, Kwang-Sub Yoon, Byoung-il Choi, Vladimir Levinski, Daniel Kandel, Yoel Feler, Nadav Gutman, Eltsafon Island-Ashwal, Moshe Cooper, DongSub Choi, Eitan Herzel, Tien David, and JungWook Kim "Scanner focus metrology for advanced node scanner monitoring and control", Proc. SPIE 9424, Metrology, Inspection, and Process Control for Microlithography XXIX, 94242E (19 March 2015);

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