Photodetector Electrode Rearrangement for Crosstalk Reduction
Solution Overview
Problem
Current photodetectors for imaging and sensing applications face challenges in enhancing light detection characteristics, particularly in pixel arrays, where the existing designs often require a large number of wiring lines on the light incidence surface, leading to increased complexity and noise due to crosstalk between pixels.
Innovation Solution
A photodetector design featuring a semiconductor substrate with multiple photoelectric conversion sections, including regions of different electrical conduction types, where the third region absorbs incident light and is electrically coupled to electrodes on both surfaces, reducing the need for wiring lines on the light incidence surface and minimizing crosstalk by using a pixel separation layer and control gate to control potential barriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional photodetector design with multiple wiring lines on the light incidence surface is used, then electrical connection to photoelectric conversion sections is achieved, but device complexity and noise due to crosstalk increase
Solution Approach 1:
The patent moves the second electrode from the light incidence surface to the opposite surface of the semiconductor substrate. This dimensional repositioning allows the second electrode to be electrically coupled to the second region from the second surface side, eliminating the need for wiring lines on the light incidence surface and reducing device complexity while maintaining reliable electrical connection
Solution Approach 2:
The patent inverts the conventional arrangement by placing the second electrode on the opposite surface rather than on the light incidence surface. This inversion resolves the contradiction by reducing wiring complexity on the critical light incidence surface while maintaining proper electrical coupling to the photoelectric conversion sections
2Reliability
If more wiring lines are provided on the light incidence surface, then electrical connection to photoelectric conversion sections is improved, but noise due to crosstalk between pixels increases
Solution Approach 1:
The patent extracts the second electrode from the light incidence surface and relocates it to the opposite surface. This extraction removes the source of potential crosstalk noise from the light incidence surface while maintaining necessary electrical connections through the substrate, thereby reducing harmful crosstalk effects
Solution Approach 2:
The semiconductor substrate itself acts as an intermediary medium, allowing electrical coupling between the second electrode on the opposite surface and the second region. This intermediary approach enables electrical connection without requiring direct wiring lines on the light incidence surface, thus avoiding crosstalk noise
3Reliability
If the aperture ratio is increased to improve light absorption, then detection sensitivity increases, but pixel structure becomes less compact
Solution Approach 1:
By relocating the second electrode to the opposite surface of the substrate, the patent enables a more compact in-plane pixel structure. The light incidence surface can be fully dedicated to light reception without wiring obstructions, maximizing aperture ratio and detection sensitivity while maintaining compact overall pixel dimensions through vertical stacking
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 enhances light detection characteristics by reducing noise and increasing the aperture ratio, allowing for more efficient light absorption and improved sensitivity while maintaining a compact pixel structure.
Implementation Method 1
The third region absorbs incident light
Data Source
AI summary
A photodetector including a plurality of photoelectric conversion sections that is provided to a semiconductor substrate. The photoelectric conversion sections each include a first region of a first electrical conduction type that is provided on a first surface side of the semiconductor substrate, a second region of a second electrical conduction type that is provided on a second surface side of the semiconductor substrate opposite to the first surface, a third region of a third electrical conduction type that is provided in a region between the first region and the second region of the semiconductor substrate, a first electrode that is electrically coupled to the first region from the first surface side, and a second electrode that is electrically coupled to the second region from the second surface side. The third region absorbs incident light.