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Proceedings Paper

Improving chip performance by photomask tuning: ultimate intra-field CD control as a major part of an overall excursion prevention strategy
Author(s): Rolf Seltmann; Aravind Narayana Samy; Thomas Thamm; Ofir Sharoni; Yael Sufrin; Avi Cohen; Thomas Scheruebl
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Paper Abstract

Excursion prevention is one of the key points in the mission of leading edge foundries. In this paper, we concentrate on patterning excursions and how to prevent them. This strategy concentrates pro-actively on the task to minimize the distributions of critical input parameters as much as possible, independently upon a certain pre-defined specification is met or not. In our paper, we will describe this concept by improving intra-field CDU using CD Correction (CDC) by mask tuning. Mask Tuning by the ForTune system uses ultra-short pulse laser technology to locally change the mask transmission, based on the wafer intra-field CDU, and hence improves CDU on wafer (CDC). To ensure a save patterning with a large enough process window without any negative yield or reliability impact, our concept looks for the tail of the final CD distribution instead of traditional 3-sigma numbers. By using a calibrated 3D resist model, we simulate the wafer CD distribution under all combinations of the Litho input parameter distributions dose, focus and mask CDU. As a result of the simulation, we get thousands of CD-results. The tail of that CD distribution still needs to be larger than the minimum CD needed for a safe etch transfer. Based on our simulation data we can calculate patterning failure probabilities and thus expected yield loss for the different patterning cases, including systematic process deviations (mask, dose, focus). At the final step, we will show in detail how the pro-active optimization of intra-field CDU by Mask Tuning using the ForTune CDC process will give us more patterning margin and thus will reduce the failure probability dramatically. The calculated yield loss for the worst scenario (focus and dose offset additionally to the mask signature) will be reduced from several percentages close to zero.

Paper Details

Date Published: 3 October 2019
PDF: 10 pages
Proc. SPIE 11148, Photomask Technology 2019, 111480L (3 October 2019); doi: 10.1117/12.2536896
Show Author Affiliations
Rolf Seltmann, RS Lithoconsult (Germany)
Aravind Narayana Samy, GLOBALFOUNDRIES Dresden Module Two, GmbH & Co. KG (Germany)
Thomas Thamm, GLOBALFOUNDRIES Dresden Module Two, GmbH & Co. KG (Germany)
Ofir Sharoni, Carl Zeiss SMS Ltd. (Israel)
Yael Sufrin, Carl Zeiss SMS Ltd. (Israel)
Avi Cohen, Carl Zeiss SMS Ltd. (Israel)
Thomas Scheruebl, Carl Zeiss SMS Ltd. (Israel)

Published in SPIE Proceedings Vol. 11148:
Photomask Technology 2019
Jed H. Rankin; Moshe E. Preil, Editor(s)

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