Paper
27 March 2007 New color alignment for CMOS image sensor
Miri Kish Dagan, Remi Edart, Hadas Rechtman, Yehuda Kanfi, Patrick Warnaar, Oshri Moshe, Richard van Haren
Author Affiliations +
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.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Miri Kish Dagan, Remi Edart, Hadas Rechtman, Yehuda Kanfi, Patrick Warnaar, Oshri Moshe, and Richard van Haren "New color alignment for CMOS image sensor", Proc. SPIE 6520, Optical Microlithography XX, 65204M (27 March 2007); https://doi.org/10.1117/12.712200
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KEYWORDS
Metals

Optical alignment

Semiconducting wafers

Overlay metrology

Data transmission

Oxides

Scanning probe microscopy

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