Avalanche Photodiode Pixel Isolation for Low-Leakage Imaging

The patent divides the semiconductor layer into multiple depth positions with distinct semiconductor regions (first, second, third, and fourth regions) having different conductivity types and doping concentrations. This segmentation allows the anode and cathode regions to be spatially separated in the depth direction while maintaining small pixel area for high resolution, thereby reducing leakage current without sacrificing resolution.

The patent transitions from a planar arrangement to a three-dimensional structure by positioning semiconductor regions at different depth positions (first, second, third, and fourth depth positions). The dielectric material extends from the second surface into the semiconductor layer, creating isolation in the depth dimension. This allows reduced pixel area for high resolution while managing leakage current through vertical separation rather than relying solely on lateral distance.

The patent segments the semiconductor layer into multiple regions at different depth positions with controlled doping concentrations. The first and third semiconductor regions (first conductivity type) and second and fourth semiconductor regions (second conductivity type) are positioned to maintain appropriate distances while enabling avalanche multiplication. This segmentation ensures stable avalanche multiplication by preventing excessive field concentration that would occur with too-close anode-cathode spacing.

The patent applies different doping concentrations and conductivity types to specific regions at different depth positions. The dielectric material is strategically positioned to locally modify the electric field distribution. This local quality control allows the anode and cathode regions to be positioned closer for high resolution while maintaining stable avalanche multiplication through localized field management and proper doping profiles.

The patent segments the pixel structure into multiple depth-layered semiconductor regions with controlled doping. This segmentation allows the pixel area to be reduced for high resolution while the vertical structure manages leakage current and noise by creating distinct functional zones that prevent unwanted current paths and signal interference.

The dielectric material acts as an intermediary between the semiconductor regions at different depth positions. It provides electrical isolation and field control, reducing leakage current and noise while allowing the pixel area to be minimized for high resolution. The dielectric material mediates the interaction between anode and cathode regions, enabling small pixel size without proportionally increasing noise.