Pixel/DRAM/logic 3-layer stacked CMOS image sensor technology

Abstract

We developed a CMOS image sensor (CIS) chip, which is stacked pixel/DRAM/logic. In this CIS chip, three Si substrates are bonded together, and each substrate is electrically connected by two-stacked through-silica vias (TSVs) through the CIS or dynamic random access memory (DRAM). We obtained low resistance, low leakage current, and high reliability characteristics of these TSVs. Connecting metal with TSVs through DRAM can be used as low resistance wiring for a power supply. The Si substrate of the DRAM can be thinned to 3 pm, and its memory retention and operation characteristics are sufficient for specifications after thinning. With this stacked CIS chip, it is possible to achieve less rolling shutter distortion and produce super slow motion video.