Vertical Spectral Pixel Lateral Light Bending for Color Mixing
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Solution Overview
Problem
In solid-state imaging elements with a vertical spectral structure, color mixing and sensitivity reduction occur due to the absorption of incorrect wavelengths by photoelectric conversion units, leading to image quality deterioration and SN ratio degradation during color correction calculations.
Innovation Solution
Incorporating a diffraction grating or metal nanoparticle/nanowire as a spectral unit on the surface of photoelectric conversion units to laterally bend specific wavelengths of incident light, allowing only the intended wavelengths to be absorbed by corresponding units, thereby preventing color mixing and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple photoelectric conversion units are vertically stacked to enable simultaneous multi-color output, then productivity and color information acquisition are improved, but color mixing occurs and measurement precision deteriorates
Solution Approach 1:
The patent segments the optical path for each wavelength by introducing spectral units (diffraction gratings or metal nanoparticles) that laterally bend specific wavelengths to dedicated photoelectric conversion units. This segmentation prevents wavelength cross-contamination while maintaining the vertical stacked structure for simultaneous multi-color detection.
Solution Approach 2:
Spectral units act as intermediary elements between incident light and photoelectric conversion units. These intermediaries laterally bend specific wavelengths before they reach the photoelectric conversion units, ensuring that each unit receives only its designated wavelength range and preventing color mixing.
2Device complexity
If photoelectric conversion units are arranged in vertical layers, then device complexity is reduced compared to lateral arrangements, but color mixing occurs causing image quality deterioration
Solution Approach 1:
The patent introduces a lateral dimension to the optical path by using spectral units to bend light horizontally across the pixel. This dimensional change allows the vertical stacked structure to achieve spectral separation without increasing vertical complexity, maintaining device simplicity while improving image quality.
3Measurement precision
If spectral sensitivity is increased by thickening photoelectric conversion units, then sensitivity is improved, but color mixing from adjacent wavelengths increases
Solution Approach 1:
The patent applies local quality by making each photoelectric conversion unit selectively responsive to a specific wavelength range through the lateral bending action of spectral units. Each unit's effective sensitivity is localized to its designated wavelength, preventing the color mixing that would occur with uniformly thick units exposed to all wavelengths.
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
The solution effectively suppresses color mixing and sensitivity reduction, improving image quality and reducing noise propagation in color correction calculations by ensuring each wavelength is absorbed by the appropriate unit, thus enhancing the spectral sensitivity characteristics.
Implementation Method 1
a first spectral unit formed on an upper surface of the first photoelectric conversion unit and configured to laterally bend a traveling direction of the light having the first wavelength of the incident light
Implementation Method 2
a first photoelectric conversion unit configured to generate an electric charge in accordance with light having a first wavelength among incident light, a second photoelectric conversion unit configured to generate an electric charge in accordance with light having a second wavelength among the incident light
Data Source
AI summary
The present disclosure relates to a solid-state imaging element and an electronic apparatus capable of suppressing color mixing and sensitivity reduction in each of pixels of a solid-state imaging element having a vertical spectral structure. A solid-state imaging element according to a first aspect of the present disclosure is a solid-state imaging element including a vertical spectral structure pixel containing a plurality of photoelectric conversion units stacked in layers. The vertical spectral structure pixel includes a first photoelectric conversion unit configured to generate an electric charge in accordance with light having a first wavelength among incident light, a second photoelectric conversion unit configured to generate an electric charge in accordance with light having a second wavelength among the incident light that has been transmitted through the first photoelectric conversion unit, and a first spectral unit formed on an upper surface of the first photoelectric conversion unit and configured to laterally bend a traveling direction of the light having the first wavelength of the incident light. The present disclosure is applicable to an electronic apparatus including an image sensor, for example.