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Proceedings Paper

Effective use of aerial image metrology for calibration of OPC models
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Paper Abstract

The appropriate representation of the photomask in the simulation of wafer lithography processes has been shown to be of vital importance for 14-nm and below [1]. This task is difficult, since accurate optical metrology and physical metrology of the three-dimensional mask structure is not always available. OPC models for wafer patterning comprise representations of the mask, the optics, and the photoresist process. The traditional calibration of these models has involved empirical tuning of model parameters to CD-SEM data from printed photoresist patterns. Such a flow necessarily convolves the resist effects and it has been difficult to reliably obtain mask and optical parameters which are most representative of physical reality due to aliasing effects. In this work, we have undertaken to decouple the mask model from the photoresist process by use of the ZEISS Wafer-Level CD (WLCD) tool based upon aerial image metrology. By measuring the OPC test pattern mask with WLCD, the mask parameters in the OPC model can be tuned directly without interference of resist effects. This work utilized 14-nm,10-nm, and 7-nm node masks, and we demonstrate that the use of such a flow leads to the most predictive overall OPC models, and that the mask parameters resulting from this flow more closely match the expected physical values. More specifically, the mask corner rounding, sidewall angle, and bias values were tuned to the WLCD data instead of the wafer CD SEM data, and resulted in improved predictive capability of the model. Furthermore, other mask variables not traditionally tuned can be verified or tuned by matching simulation to aerial image metrology.

Paper Details

Date Published: 24 March 2017
PDF: 12 pages
Proc. SPIE 10147, Optical Microlithography XXX, 101470Y (24 March 2017); doi: 10.1117/12.2258632
Show Author Affiliations
Ao Chen, GLOBALFOUNDRIES Singapore (Singapore)
Yee Mei Foong, GLOBALFOUNDRIES Singapore (Singapore)
Thomas Thaler, Carl Zeiss AG (Germany)
Ute Buttgereit, Carl Zeiss AG (Germany)
Angeline Chung, Mentor Graphics Asia Pte Ltd. (Singapore)
Andrew Burbine, Mentor Graphics Corp. (United States)
John Sturtevant, Mentor Graphics Corp. (United States)
Chris Clifford, Mentor Graphics Corp. (United States)
Kostas Adam, Mentor Graphics Corp. (United States)
Peter DeBisschop, IMEC (Belgium)


Published in SPIE Proceedings Vol. 10147:
Optical Microlithography XXX
Andreas Erdmann; Jongwook Kye, Editor(s)

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