5.6 A 1/2.65in 44Mpixel CMOS Image Sensor with 0.7µm Pixels Fabricated in Advanced Full-Depth Deep-Trench Isolation Technology

As the smart mobile device market continues to grow and the number of cameras per device rapidly increases, demand for CMOS image sensors (CIS) also increases. Two major trends in mobile device cameras are: (1) adopting smaller pixels that enable greater pixel count at similar optical format, and (2) bigger pixels for higher image quality. To be more specific, front-facing cameras have a trend towards smaller pixels, while rear main cameras have a trend towards both smaller and bigger pixels. The optical format of front-facing cameras is especially limited due to existing bezel-less or border-less display designs, yet higher resolution still-shot and video (such as 4K UHD) recording is desired. To implement greater pixel count in a limited camera module size, scaling of pixel size is required. The main challenges are to maintain acceptable photodiode full-well capacity (FWC) and sensitivity, while suppressing optical crosstalk [1]. To completely eliminate both electrical and optical crosstalk, deep-trench isolation (DTI) has evolved from early BDTI (Back-side DTI) to current FDTI (Front-side DTI) technology, which is also called full-depth DTI. In this paper, a 44Mpixel CIS with 0.7μm pixels using full-depth DTI is demonstrated.