Embodiments of the disclosed subject matter relate to image sensors, and, more particularly, to image sensors that extract color or other wavelength-related information, including those that do so with the aid of multi-height light-sensing regions.
Conventional image sensors (CIS, CCD, etc.) typically use a color filter array (CFA) to extract color information to construct color images. A common method uses Red (R), Green (G), and Blue (B) color filters.
The color filter materials themselves absorb some photons, resulting in loss of quantum efficiency, and hence a lower signal-to-noise ratio (SNR).
Thick color filter material also results in worse Chief-Ray Angle (CRA), which is important in designing thinner camera modules and incorporating large aperture lenses.
Additionally, CFA process variations, such as thickness, size, and alignment, may cause excess crosstalk, where a portion of light intended to impinge only a first class of pixel regions associated with a first intended color in fact is incident on a second class associated with a second color. Such CFA process variations may also produce non-uniformity issues, further lowering the SNR, resulting in poor images.
Furthermore, a CFA is often responsible for reliability failures, and obvious process costs associated with the CFA process and yield loss are undesirable.