Kimiaki Toshikiyo

A MOS Image Sensor With a Digital-Microlens

We have developed a MOS image sensor with digital-microlenses (DMLs), each of which has an effective refractive index realized by variation of the subwavelength separations between the concentric SiO2 ring walls. The effective refractive index profiles are optimized for the location of each pixel. The light-collection efficiency of the image sensor is twice as high as that of a conventional image sensor because of the enhanced light acceptance in the periphery. A 2.2-mum pitch 3-megapixel MOS image sensor based on the DML technology exhibited excellent uniformity of the light-collection efficiency across the image area, even for light with a very large incident angle, i.e., over 45deg. The DML promises new levels of performance of image sensors.

A MOS Image Sensor with Microlenses Built by Sub-Wavelength Patterning

A MOS image sensor has digital-microlenses implemented by sub-wavelength patterning of concentric SiO2 ring walls. The sensitivity at the periphery of the imager is 3000e-/1x-s. In comparison, the sensitivity at the periphery of a conventional imager is 1300e/1x-s. Thus, extremely uniform brightness throughout the reproduced image is demonstrated even with an angle of incidence > 45deg.