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Proceedings Paper

On-chip polarizer on image sensor using advanced CMOS technology
Author(s): Kiyotaka Sasagawa; Norimitsu Wakama; Toshihiko Noda; Takashi Tokuda; Kiyomi Kakiuchi; Jun Ohta
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Paper Abstract

The structures in advanced complementary metal-oxide-semiconductor (CMOS) integrated circuit technology are in the range of deep-submicron. It allows designing and integrating nano-photonic structures for the visible to near infrared region on a chip. In this work, we designed and fabricated an image sensor with on-pixel metal wire grid polarizers by using a 65-nm standard CMOS technology. It is known that the extinction ratio of a metal wire grid polarizer is increased with decrease in the grid pitch. With the metal wire layers of the 65-nm technology, the grid pitch sufficiently smaller than the wavelengths of visible light can be realized. The extinction ratio of approximately 20 dB has been successfully achieved at a wavelength of 750 nm. In the CMOS technologies, it is usual to include multiple metal layers. This feature is also useful to increase the extinction ratio of polarizers. We designed dual layer polarizers. Each layer partially reflects incident light. Thus, the layers form a cavity and its transmission spectrum depends on the layer position. The extinction ratio of 19.2 dB at 780 nm was achieved with the grid pitch greater than the single layer polarizer. The high extinction ratio is obtained only red to near infrared region because the fine metal layers of deepsubmicron standard CMOS process is usually composed of Cu. Thus, it should be applied for measurement or observation where wide spectrum is not required such as optical rotation measurement of optically active materials or electro-optic imaging of RF/THz wave.

Paper Details

Date Published: 7 March 2014
PDF: 6 pages
Proc. SPIE 8974, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VII, 89740I (7 March 2014); doi: 10.1117/12.2040012
Show Author Affiliations
Kiyotaka Sasagawa, Nara Institute of Science and Technology (Japan)
Norimitsu Wakama, Nara Institute of Science and Technology (Japan)
Toshihiko Noda, Nara Institute of Science and Technology (Japan)
Takashi Tokuda, Nara Institute of Science and Technology (Japan)
Kiyomi Kakiuchi, Nara Institute of Science and Technology (Japan)
Jun Ohta, Nara Institute of Science and Technology (Japan)


Published in SPIE Proceedings Vol. 8974:
Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VII
Georg von Freymann; Winston V. Schoenfeld; Raymond C. Rumpf, Editor(s)

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