Stacked Pixel Wire and Trench Layout for Fine-Pitch Imaging

The patent transitions from planar pixel arrangement to three-dimensional stacking, arranging photodiodes, floating diffusions, and pixel circuits across multiple layers (first substrate, second substrate, third substrate) in the vertical direction. This dimensional change enables increased pixel density without expanding chip area, as pixels are distributed through the thickness of the device rather than only across the surface.

The patent implements nested positioning where components are vertically aligned across multiple substrates. Specifically, the photodiode in the first substrate, floating diffusion in the second substrate, and pixel circuit in the third substrate are positioned to overlap or align vertically, creating a compact nested structure that maximizes space utilization and maintains small chip footprint while achieving high pixel density.

The patent moves the electrical connection from a planar via structure to a three-dimensional wire structure that extends vertically through the substrates. The wire penetrates the first and second substrates to connect the floating diffusion to the pixel circuit, distributing the connection path through the thickness of the device rather than confining it to the surface plane, thereby reducing the area occupied in the pixel region.

The patent introduces a wire as an intermediary element that spans multiple substrates to establish electrical connection. Instead of using a via that occupies significant area within the pixel region, the wire acts as a mediator that connects components across layers with minimal intrusion into the effective pixel circuit area, as it can be routed through interlayer insulating films and bonding interfaces.

The patent divides the device into three separate substrates (first substrate with photodiode, second substrate with floating diffusion, third substrate with pixel circuit) connected by wires penetrating through them. This segmentation allows the wire to be formed in stages during manufacturing, reducing the complexity of forming long penetrating wires compared to creating single continuous connections through all layers at once. Each substrate can be processed and wired separately before final assembly.

The patent enables preliminary formation of wires and connections in each substrate before final assembly. The wires can be formed in interlayer insulating films of individual substrates prior to bonding, allowing pre-configuration of electrical connections. This preliminary action simplifies the overall manufacturing process by breaking down the complex task of creating through-substrate connections into manageable steps that can be performed on each substrate independently.