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Proceedings Paper

New color alignment for CMOS image sensor
Author(s): Miri Kish Dagan; Remi Edart; Hadas Rechtman; Yehuda Kanfi; Patrick Warnaar; Oshri Moshe; Richard van Haren
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Paper Abstract

A new alignment mark implementation for color processing has been successfully tested in a joint activity between ASML and TOWER. Alignability and overlay performance have been proven by applying the combination of a pure high order mark design and a dual implementation using the ATHENATM alignment sensor and a PAS5500/400 machine. By their very nature, the resists used in color filter processes will absorb light at various wavelengths. While this makes them useful as color filters, it can noticeably reduce the signal strength of pattern images as seen by lithography alignment systems. The pure high order mark design enhances the signal strength. Exposing two of such mark pairs in a Metal Last layer with two different metal plateaus (in previous metal layers: "Metal Last - 1" and "Metal Last -2") leads to two different optical mark depths and therefore mimics a four wavelength alignment system with ATHENA. In principle, the evaluated technique might be extended to more (than four) "wavelengths" as well as other process layers. Moreover, the use of scribe-line marks enhances productivity since no extra lithography step is required to expose Zero Layers. The performance of this implementation has been evaluated for 180-nm CMOS Image Sensor technology. This paper discusses the overlay and alignment results of the evaluation. Alignment parameters such as absolute signal strength and signal strength variation were studied in detail. It is shown that such mark implementation shows good alignability and easily meets the product overlay requirements of Image Sensor devices.

Paper Details

Date Published: 27 March 2007
PDF: 12 pages
Proc. SPIE 6520, Optical Microlithography XX, 65204M (27 March 2007); doi: 10.1117/12.712200
Show Author Affiliations
Miri Kish Dagan, Tower Semiconductor, Ltd. (Israel)
Remi Edart, ASML Netherlands B.V. (Netherlands)
Hadas Rechtman, Tower Semiconductor Ltd. (Israel)
Yehuda Kanfi, ASML Netherlands B.V. (Netherlands)
Patrick Warnaar, ASML Netherlands B.V. (Netherlands)
Oshri Moshe, Tower Semiconductor, Ltd. (Israel)
Richard van Haren, ASML Netherlands B.V. (Netherlands)

Published in SPIE Proceedings Vol. 6520:
Optical Microlithography XX
Donis G. Flagello, Editor(s)

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