Challenges and opportunities in small pixel development for novel CMOS image sensors

As pixels continue to shrink, increasingly complicated structures are being used to maintain performance. Some of these involve novel processes like wafer thinning and bonding, while others involve novel device or optical structures like light-pipes. The development of 3D interconnect and packaging technologies has also allowed new sensor structures to be developed that allow further customization to imaging. Whether these will be commercially viable, will depend on the cost-effectiveness of developing and manufacturing such structures. Despite the fact that increasingly complicated structures are being used, as we reach pixels with sizes 1.1um and below, system MTF does not continue to scale in performance with the increased pixel sampling frequency. However, the increased pixel sampling frequency can be used to support novel functionality such as High Dynamic Range Imaging or time-interleaved sampling for other applications like depth sensing and stereo vision.