Global Shutter Pixel Trench Layout for Parasitic Light Blocking

The patent applies asymmetry by making the light-blocking section asymmetric with respect to the charge accumulating unit. Specifically, the light-blocking section is positioned closer to the image height end than to the image height center, creating an asymmetric configuration that compensates for the oblique incidence of light at image height ends. This asymmetric positioning ensures that light-blocking performance is uniform across the entire image height, resolving the contradiction between reducing parasitic light sensitivity and achieving uniform cover effectiveness.

The patent resolves the contradiction by transitioning from a planar light-blocking approach to a three-dimensional trench structure. The light-blocking section is formed as a trench that extends in the depth direction (vertical dimension) within the semiconductor substrate, rather than merely as a surface layer. This dimensional change allows the trench to effectively block oblique incident light at image height ends without increasing the lateral footprint, thereby maintaining opening size while achieving uniform light blocking across the image height.

The patent applies merging by integrating the light-blocking function directly into the existing trench structure used for other purposes in the global shutter architecture. Rather than adding separate light-blocking films as independent components, the light-blocking section is merged with the trench structure that already exists in the semiconductor substrate. This integration achieves oblique incidence light blocking without increasing device complexity, as the light-blocking function is combined with the existing structural elements.