Image sensors with multi-photodiode image pixels and vertical transfer gates

Abstract

Image sensors may include an array of pixels each having nested sub-pixels. Nested sub-pixels may include an inner photosensitive region and an outer photosensitive region. Inner photosensitive regions of pixels in an array may be provided with a respective local vertical transfer gate structure formed in a trench that laterally surrounds the inner photosensitive region. A trench structure may be formed in a grid-like pattern having gaps in which the nested sub-pixels are formed. The trench structure may be coupled to outer photosensitive regions of each of the pixels in the array. The trench structure may be a global vertical transfer gate structure. The vertical transfer gate structures provided to the pixels may allow for accumulated charges to be transferred to respective charge storage nodes associated with the photosensitive regions in any given pixel. Image sensors formed in this way may be used in rolling shutter or global shutter configurations.