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Proceedings Paper

4-micron-pixel CMOS image sensor with low-image lag and high-temperature operability
Author(s): Yasuyuki Endo; Yoshikazu Nitta; Hiroshi Kubo; Takeshi Murao; Ken'ichi Shimomura; Masatoshi Kimura; Kenji Watanabe; Satoshi Yamamoto; Shinji Komori
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Paper Abstract

We present a development of a high image quality color VGA CMOS image sensor with 4-micron pixel pitch, especially focusing on reduction of image lag. In order to eliminate image lag, improvement of charge transfer efficiency from photodiode (PD) to floating diffusion (FD) is a key point. We implemented two novel techniques for this purpose. The first technical point is an optimum design of pixel layout, which provides both high fill factor and a large channel width of transfer gate transistor (TG). We achieved both high fill factor of 42% without microlens and large TG channel width of 1.79um, which is 2.4 times larger than the minimum channel width allowed by design rule. The second technical point is a new device structure of TG by a novel Boron implantation process. This brings a wide path of charge transfer from PD to FD. High-quality images with low image lag, less than 0.75%, were obtained. Moreover, we also achieved a CMOS image sensor with high-temperature operability. In order to stabilize an adequate black level, we developed a new scheme of a black level control that adjusts offset voltages of amplifiers with feedback signal from analog-digital converter (ADC). An adequate black level was realized up to 100 degrees centigrade for a 5.6-micron pitch monochrome CIF sensor.

Paper Details

Date Published: 16 May 2003
PDF: 9 pages
Proc. SPIE 5017, Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV, (16 May 2003); doi: 10.1117/12.482802
Show Author Affiliations
Yasuyuki Endo, Mitsubishi Electric Corp. (Japan)
Yoshikazu Nitta, Mitsubishi Electric Corp. (Japan)
Hiroshi Kubo, Mitsubishi Electric Corp. (Japan)
Takeshi Murao, LTEC Corp. (Japan)
Ken'ichi Shimomura, Mitsubishi Electric Corp. (Japan)
Masatoshi Kimura, Mitsubishi Electric Corp. (Japan)
Kenji Watanabe, LTEC Corp. (Japan)
Satoshi Yamamoto, Mitsubishi Electric Corp. (Japan)
Shinji Komori, Mitsubishi Electric Corp. (Japan)

Published in SPIE Proceedings Vol. 5017:
Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV
Nitin Sampat; Ricardo J. Motta; Morley M. Blouke; Nitin Sampat; Ricardo J. Motta, Editor(s)

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