We introduce a 1.58μm back illuminated CMOS image-sensor (BI CIS) which contains 4 Mega 2×1 shared on-chip micro-lenses (OCL). With this architecture, we realize a full phase-detection auto focus (PDAF) CIS, where all photo detectors (PDs) are L/R paired with a common OCL, the same color on-chip-color-filter (OCCF) and without metal grid between the L/R pixel boundary. The device has a good separation ratio of 2.59 and is more than twice sensitive under normal incident 550nm plane wave compared to current state-of-the-art PDAF pixels with half metal-shielded aperture. Because the device has no obstacle structure on its optical path, it hardly suffers from reflection and diffraction of the incident light. This feature is adequate to realize PDAF function especially for the CISs with smaller pixels. In addition, the OCCF configuration of the device is a 45° rotated to Bayer CF pattern, and hence, every 2 lines contain only Green pixels. This CF configuration makes it suitable to detect the phase difference between L and R sub-images. Furthermore, this architecture is in particular suitable for HDR imaging by varying the exposure times for each L and R sub-images because it is possible to capture two set of sub-images with almost identical optical characteristics to the on-focus object. In this paper, we report on the device performance and propose versatile applications including high-sensitive AF and HDR for the full-PDAF CIS.
