Pixel-Border Polysilicon Layout for Low-Crosstalk Photodetectors
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Solution Overview
Problem
Existing photodetectors face challenges in improving pressure resistance performance while minimizing crosstalk between adjacent pixels, particularly in miniaturized designs.
Innovation Solution
The photodetector incorporates a layout of polysilicon films and connection wirings that are electrically coupled through openings in the insulating layer, forming a continuous border around each pixel to prevent light leakage and maintain a significant distance between the anode and cathode, thereby enhancing pressure resistance and reducing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pixel size is reduced for miniaturization, then the device size is reduced, but the pressure resistance performance deteriorates due to reduced distance between anode and cathode
Solution Approach 1:
The patent introduces a vertical dimension by stacking the insulating layer and polysilicon films above the semiconductor substrate surface. This three-dimensional arrangement allows the light-shielding structure to extend upward, effectively increasing the distance between anode and cathode in the vertical direction while maintaining small pixel footprint in the horizontal plane, thus resolving the contradiction between miniaturization and pressure resistance.
Solution Approach 2:
The patent introduces an intermediary structure consisting of the insulating layer and polysilicon films that are electrically coupled to the light-receiving section. This intermediary arrangement provides both electrical connection and physical separation, maintaining the necessary distance between electrodes while enabling functional connectivity, thereby improving pressure resistance without compromising device operation.
2Productivity
If the distance between adjacent pixels is reduced, then the pixel density is increased, but crosstalk between adjacent pixels increases due to light leakage
Solution Approach 1:
The patent utilizes the vertical dimension by stacking the insulating layer and polysilicon films above the substrate surface. This three-dimensional light-shielding structure effectively blocks light leakage between adjacent pixels without requiring increased horizontal spacing, thereby enabling high pixel density while suppressing crosstalk.
Solution Approach 2:
The patent employs a composite structure combining the insulating layer and polysilicon films to create an effective light-shielding barrier. This composite arrangement provides both electrical functionality and optical isolation, allowing adjacent pixels to be placed closer together while preventing crosstalk through the combined light-blocking properties of the layered structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design improves pressure resistance against edge breakdown and suppresses crosstalk, facilitating the miniaturization of photodetector pixels while maintaining effective signal detection.
Implementation Method 1
a light-receiving section that is provided inside the first semiconductor substrate for each of the pixels, and generates carriers corresponding to a received light amount by photoelectric conversion
Implementation Method 2
a multiplication section that is provided on the first surface for each of the pixels, and performs avalanche multiplication of the carriers generated in the light-receiving section
Data Source
AI summary
A photodetector of an embodiment of the disclosure includes: a first semiconductor substrate having a first surface and a second surface and including a pixel array section; a light-receiving section inside the first semiconductor substrate for each of the pixels that generates carriers corresponding to a received light amount; a multiplication section; an insulating layer stacked on the first surface and having an opening; a polysilicon film with the insulating layer interposed between the first surface and the polysilicon film along at least a border of the pixels that is electrically coupled to the light-receiving section through the opening; a first wiring along an outer shape of each of the pixels on the side of the first surface; and a first connection wiring along the outer shape of each of the pixels on the side of the first surface that electrically couples the polysilicon film and the first wiring.