Organic Image Sensor Wiring Structure for Uniform Pixel Drive Voltage
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Solution Overview
Problem
In conventional laminated solid-state imaging elements, there is a variation in drive voltage between peripheral and central light receiving pixels due to higher voltage drop in transparent wiring with high resistance, affecting the stability of the pixel array unit operation.
Innovation Solution
A solid-state imaging element with a pixel array unit where each light receiving pixel includes an organic photoelectric conversion unit and another conversion unit, connected via a connection wiring that combines metal and transparent conductive films, with the metal wiring extending horizontally from the pixel's peripheral portion to the array unit, reducing resistance and stabilizing the drive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transparent wiring is used to connect the second electrode to the peripheral portion, then the pixel array unit can be formed with a simple structure, but the resistance is high causing voltage drop and unstable operation
Solution Approach 1:
The connection wiring is formed as a composite structure combining transparent wiring (first conductive film) and metal wiring (second conductive film). The transparent wiring extends from the second electrode to the peripheral portion, and the metal wiring is connected to the transparent wiring at the peripheral portion to extend toward the central portion, reducing overall resistance and voltage drop while maintaining structural integrity
2Reliability
If transparent wiring with high resistance is used, then the manufacturing process is simple, but the drive voltage varies between peripheral and central pixels affecting operation stability
Solution Approach 1:
The connection wiring is segmented into two functional parts: transparent wiring that connects the second electrode to the peripheral portion, and metal wiring that connects at the peripheral portion and extends toward the central portion. This segmentation allows each material to perform its optimal function while maintaining a relatively simple overall structure
3Loss of energy
If metal wiring is used to reduce resistance, then voltage drop is reduced, but the manufacturing complexity increases
Solution Approach 1:
Metal wiring is strategically placed only at the peripheral portion where it can most effectively reduce resistance in the connection path, while transparent wiring handles the connections where it suffices. This local application of different materials optimizes electrical performance while minimizing manufacturing complexity
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 configuration stabilizes the operation of the entire pixel array unit by minimizing voltage drops and maximizing the quantum efficiency and saturation charge amount of the photodiode, while allowing more light to reach the photodiode.
Implementation Method 1
a photoelectric conversion layer made of an organic semiconductor material
Implementation Method 2
a metal wiring made of metal and a transparent wiring made of a transparent conductive film. The metal wiring extends in a horizontal direction from a peripheral portion of the light receiving pixel to a peripheral portion of the pixel array unit
Data Source
AI summary
A solid-state imaging element (1) according to the present disclosure includes a pixel array unit (10) in which a plurality of light receiving pixels (11) is two-dimensionally arranged. Each of the light receiving pixels (11) includes an organic photoelectric conversion unit (61) and another photoelectric conversion unit. The organic photoelectric conversion unit (61) includes a photoelectric conversion layer (63) made of an organic semiconductor material, a first electrode (62) located on a light incident side of the photoelectric conversion layer (63), and a second electrode (65) located on a side opposite to the light incident side of the photoelectric conversion layer (63). The other photoelectric conversion unit is located on a side opposite to the light incident side of the organic photoelectric conversion unit (61), and performs photoelectric conversion in a wavelength region different from a wavelength region of the organic photoelectric conversion unit (61). The second electrode (65) is connected to a connection wiring (51) including a metal wiring (54) made of metal and a transparent wiring (53) made of a transparent conductive film. The metal wiring (54) extends in a horizontal direction from a peripheral portion of the light receiving pixel (11) to a peripheral portion of the pixel array unit (10).