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Proceedings Paper

In-chip optical CD measurements for non-volatile memory devices
Author(s): Mauro Vasconi; Stephanie Kremer; M. Polli; Ermes Severgnini; Silvia S. Trovati
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Paper Abstract

A potential limitation to a wider usage of the scatterometry technique for CD evaluation comes from its requirement of dedicated regular measurement gratings, located in wafer scribe lanes. In fact, the simplification of the original chip layout that is often requested to design these gratings may impact on their printed dimension and shape. Etched gratings might also suffer from micro-loading effects other than in the circuit. For all these reasons, measurements collected therein may not represent the real behavior of the device. On the other hand, memory devices come with large sectors that usually possess the characteristics required for a proper scatterometry evaluation. In particular, for a leading edge flash process this approach is in principle feasible for the most critical process steps. The impact of potential drawbacks, mainly lack of pattern regularity within the tool probe area, is investigated. More, a very large sampling plan on features with equal nominal CD and density spread over the same exposure shot becomes feasible, thus yielding a deeper insight of the overall lithographic process window and a quantitative method to evaluate process equipment performance along time by comparison to acceptance data and/or last preventive maintenance. All the results gathered in the device main array are compared to those collected in standard scatterometry targets, tailored to the characteristics of the considered layers in terms of designed CD, pitch, stack and orientation.

Paper Details

Date Published: 24 March 2006
PDF: 12 pages
Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 61520D (24 March 2006); doi: 10.1117/12.650997
Show Author Affiliations
Mauro Vasconi, STMicroelectronics Srl (Italy)
Stephanie Kremer, KLA-Tencor France S.A.RL. (France)
M. Polli, KLA-Tencor Italy Srl (Italy)
Ermes Severgnini, STMicroelectronics Srl (Italy)
Silvia S. Trovati, STMicroelectronics Srl (Italy)

Published in SPIE Proceedings Vol. 6152:
Metrology, Inspection, and Process Control for Microlithography XX
Chas N. Archie, Editor(s)

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