[Paper] A 3D Stacked 16Mpixel Global-shutter CMOS Image Sensor Using 4 Million Interconnections

Abstract

We have developed a 3D stacked 16Mpixel global-shutter CMOS image sensor with pixel level interconnections using four million micro bumps. The four photodiodes in the unit pixel circuit on the top substrate share one micro-bump interconnection in a 7.6μm pitch. Each signal of the photodiodes is transferred to the corresponding storage node on the bottom substrate via the interconnection to achieve a global-shutter function. The ratio of the parasitic light sensitivity of an in-pixel storage node and the light sensitivity of a photodiode is –180dB with a 3.8μm pixel. In addition, we discuss further improvement to reduce noise figure in global-shutter image sensors.