Solid-state imaging element and electronic equipment
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Solution Overview
Problem
In stacked image sensors, the sensitivity of photoelectric conversion units on the opposite side of the light incident side is deteriorated due to absorption of light in another wavelength region by the unit on the light incident side.
Innovation Solution
A solid-state imaging element is designed with a first photoelectric conversion unit made of organic material converting light in a first wavelength region, a second unit converting light in a second wavelength region on the opposite side, and a third unit converting light in a third wavelength region, with color splitters dispersing and redirecting light to improve sensitivity by preventing absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stacked image sensor with multiple photoelectric conversion units is used, then the ability to capture multiple wavelength regions is improved, but the sensitivity of units on the opposite side of the light incident side deteriorates due to light absorption by units on the light incident side
Solution Approach 1:
A light guide layer is introduced as an intermediary component between the first photoelectric conversion unit and the second photoelectric conversion unit. This light guide layer redirects transmitted light toward the second unit, ensuring that light in the second wavelength region reaches the intended photoelectric conversion unit with high efficiency while minimizing unwanted absorption by the first unit.
Solution Approach 2:
The patent applies different structural optimizations to different regions of the stacked sensor. The light guide layer is specifically designed with properties optimized for guiding light to the second unit, while the first unit maintains its photoelectric conversion function. This localized functional differentiation resolves the sensitivity issue without compromising the multi-wavelength capture capability.
2Adaptability or versatility
If light is transmitted through the first photoelectric conversion unit to reach the second unit, then multi-wavelength detection is enabled, but light absorption by the first unit reduces the intensity of light reaching the second unit
Solution Approach 1:
The light guide layer serves as a mediator that captures light transmitted through the first photoelectric conversion unit and redirects it toward the second unit. This intermediary structure minimizes energy loss by ensuring that transmitted light is efficiently directed to its intended target, thereby maintaining high light intensity at the second unit while preserving multi-wavelength detection capability.
3Device complexity
If photoelectric conversion units are stacked in the light incident direction, then compact multi-functional sensing is achieved, but sensitivity of deeper units deteriorates due to light absorption
Solution Approach 1:
The light guide layer is positioned between the first and second photoelectric conversion units to act as an intermediary that actively manages light distribution. It redirects transmitted light toward the second unit, compensating for the sensitivity deterioration that would otherwise occur in a compact stacked configuration. This allows the maintenance of a space-efficient stacked structure while preserving the sensitivity of deeper units.
Solution Approach 2:
The patent optimizes specific regions of the stacked structure to address sensitivity issues. The light guide layer is designed with local properties (such as refractive index and thickness) optimized for light guidance, while the overall stacked structure maintains its compact form factor. This localized optimization enables both compactness and high sensitivity in deeper units.
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 enhances the sensitivity of photoelectric conversion units on the opposite side of the light incident side by effectively redirecting and dispersing light, reducing absorption and improving light utilization across different wavelength regions.
Implementation Method 1
The first color splitter disperses light transmitted through the first photoelectric conversion unit
Implementation Method 2
bends the light in the third wavelength region toward the third photoelectric conversion unit
Implementation Method 3
a photoelectric conversion layer made of an organic material and photoelectrically converts light in a first wavelength region
Data Source
AI summary
A solid-state imaging element (1) includes a first photoelectric conversion unit that includes a photoelectric conversion layer (52b) made of an organic material and photoelectrically converts light in a first wavelength region, a second photoelectric conversion unit and a third photoelectric conversion unit that are disposed on an opposite side of a light incident side with respect to the first photoelectric conversion unit and photoelectrically convert light in a second wavelength region and a third wavelength region different from the first wavelength region, and a first color splitter and a second color splitter that are disposed between the first photoelectric conversion unit and the second photoelectric conversion unit and the third photoelectric conversion unit and disperse light transmitted through the first photoelectric conversion unit. The first color splitter makes the light in the second wavelength region incident on the second photoelectric conversion unit near the first color splitter and bends the light in the third wavelength region toward the third photoelectric conversion unit adjacent to the first color splitter, and the second color splitter makes the light in the third wavelength region incident on the third photoelectric conversion unit near the second color splitter and bends the light in the second wavelength region toward the second photoelectric conversion unit adjacent to the second color splitter.