Masahiro Kasano

A Day and Night Vision MOS Imager With Robust Photonic-Crystal-Based RGB-and-IR

This paper demonstrates a day and night vision MOS imager with red, green, blue (RGB) and extra near-infrared filters placed over individual pixels. The on-chip RGB and IR filters are fabricated from an inorganic photonic crystal color filter (PCCF) technology, thereby realizing a robust and reliable camera module for indoor and outdoor use without mounting a mechanical IR-cut filter. These PCCFs allow the IR band as well as the RGB bands to pass through to the RGB photodiodes from which RGB signals, each involving some amount of IR component, are derived. During the daytime, however, chromatically almost pure RGB colors are reproduced by subtracting a weighed IR signal of an extra IR pixel from the raw RGB signals of the surrounding IR pixels. As a result, the IR components in the resultant RGB signals are minimized from 25%, 21%, and 50% to 9%, 4%, and 21%, respectively. During the night, on the other hand, an IR image having a resolution match with a conventional IR imager can be captured by using the IR components of the raw RGB signals with the IR signal.

A 2.0-/spl mu/m pixel pitch MOS image sensor with 1.5 transistor/pixel and an amorphous Si color filter

In this paper, an ultrafine pixel size (2.0/spl times/2.0 /spl mu/m/sup 2/) MOS image sensor with very high sensitivity is developed. The key technologies that realize the MOS image sensor are a newly developed pixel circuit configuration (1.5 transistor/pixel), a fine 0.15-/spl mu/m design rule, and an amorphous Si color filter (Si-CF). In the new pixel circuit configuration, a unit pixel consists of one photodiode, one transfer transistor, and an amplifier circuit with two transistors that are shared by four neighboring pixels. Thus, the unit pixel has only 1.5 transistors. The fine design rule of 0.15 /spl mu/m enables reduction of wiring area by 40%. As a result, a high aperture ratio of 30% is achieved. A newly developed Si-CF realizes the 1/10 thickness of that of the conventional organic-pigment CF, giving rise to high light-collection efficiency. With these three technologies combined, a high sensitivity of 3400 electrons/lx/spl middot/s is achieved even with a pixel size of 2.0/spl times/2.0 /spl mu/m/sup 2/.