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Proceedings Paper

A hybrid solution using computational prediction and measured data to accurately determine process corrections with reduced overlay sampling
Author(s): Ben F. Noyes III; Babak Mokaberi; Ram Mandoy; Alex Pate; Ralph Huijgen; Mike McBurney; Owen Chen
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Paper Abstract

Reducing overlay error via an accurate APC feedback system is one of the main challenges in high volume production of the current and future nodes in the semiconductor industry. The overlay feedback system directly affects the number of dies meeting overlay specification and the number of layers requiring dedicated exposure tools through the fabrication flow. Increasing the former number and reducing the latter number is beneficial for the overall efficiency and yield of the fabrication process. An overlay feedback system requires accurate determination of the overlay error, or fingerprint, on exposed wafers in order to determine corrections to be automatically and dynamically applied to the exposure of future wafers. Since current and future nodes require correction per exposure (CPE), the resolution of the overlay fingerprint must be high enough to accommodate CPE in the overlay feedback system, or overlay control module (OCM). Determining a high resolution fingerprint from measured data requires extremely dense overlay sampling that takes a significant amount of measurement time. For static corrections this is acceptable, but in an automated dynamic correction system this method creates extreme bottlenecks for the throughput of said system as new lots have to wait until the previous lot is measured. One solution is using a less dense overlay sampling scheme and employing computationally up-sampled data to a dense fingerprint. That method uses a global fingerprint model over the entire wafer; measured localized overlay errors are therefore not always represented in its up-sampled output. This paper will discuss a hybrid system shown in Fig. 1 that combines a computationally up-sampled fingerprint with the measured data to more accurately capture the actual fingerprint, including local overlay errors. Such a hybrid system is shown to result in reduced modelled residuals while determining the fingerprint, and better on-product overlay performance.

Paper Details

Date Published: 28 March 2017
PDF: 6 pages
Proc. SPIE 10145, Metrology, Inspection, and Process Control for Microlithography XXXI, 1014508 (28 March 2017); doi: 10.1117/12.2257486
Show Author Affiliations
Ben F. Noyes III, SAMSUNG Austin Semiconductor LLC (United States)
Babak Mokaberi, SAMSUNG Austin Semiconductor LLC (United States)
Ram Mandoy, SAMSUNG Austin Semiconductor LLC (United States)
Alex Pate, SAMSUNG Austin Semiconductor LLC (United States)
Ralph Huijgen, ASML Netherlands B.V. (Netherlands)
Mike McBurney, ASML Netherlands B.V. (Netherlands)
Owen Chen, ASML Netherlands B.V. (Netherlands)

Published in SPIE Proceedings Vol. 10145:
Metrology, Inspection, and Process Control for Microlithography XXXI
Martha I. Sanchez, Editor(s)

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