Solid-State Imaging Device Diffractive Color Separation
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Solution Overview
Problem
Layered solid-state imaging devices face a trade-off between color reproducibility and sensitivity due to the absorption of light by general pigment-based color filters, which limits their ability to effectively separate light into different colors without significant signal loss.
Innovation Solution
The implementation of higher-refractive-index transparent parts embedded in a lower-refractive-index transparent layer within the solid-state imaging device, which separates incident light into zero-order, first-order, and negative-first-order diffracted light, allowing each color component to be directed to a specific photoelectric conversion film, thereby reducing light absorption and enhancing color reproducibility and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If general pigment-based color filters are used to separate light into different colors, then color reproducibility is improved, but sensitivity deteriorates due to light absorption
Solution Approach 1:
The patent changes the fundamental parameter of color separation from pigment-based absorption to diffraction-based separation. By using a diffraction grating structure with specific refractive indices and geometric parameters (grating constant, depth, width), light is separated into different wavelengths through constructive and destructive interference rather than absorption, thereby maintaining high sensitivity while achieving color reproducibility
Solution Approach 2:
The patent replaces the chemical/optical absorption mechanism of pigment-based color filters with a physical diffraction mechanism. The diffraction grating uses structural geometry (periodic variations in refractive index) to separate wavelengths, substituting the absorption-based color filtering approach with an interference-based approach that preserves more incident light
2Measurement precision
If pigment-based color filters are used for color separation, then color reproduction is achieved, but signal loss increases
Solution Approach 1:
The patent fundamentally changes the color separation mechanism from absorption to diffraction by modifying the optical parameters of the system. The diffraction grating structure with controlled refractive index variations and geometric parameters separates wavelengths through phase differences and interference patterns, preserving signal intensity while achieving spectral separation
Solution Approach 2:
The patent substitutes the absorption-based color filtering system with a diffraction-based wavelength separation system. This replacement eliminates the inherent signal loss associated with pigment absorption while maintaining the ability to reproduce colors through selective wavelength detection
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 allows for high-resolution and high-sensitivity imaging with reduced light volume loss during color separation, enabling improved performance and cost-effectiveness in image sensors for various applications such as digital cameras and mobile phones.
Implementation Method 1
separates incident light into zero-order, first-order, and negative-first-order diffracted light
Implementation Method 2
a photoelectric conversion film which is formed above a semiconductor substrate and converts incident light into electric charges
Data Source
AI summary
A solid-state imaging device includes: a plurality of pixel cells; and column signal lines. Each of the pixel cells includes: a photoelectric conversion film, a pixel electrode, a transparent electrode, an amplifier transistor, a reset transistor, and an address transistor. The solid-state imaging device further includes: a lower-refractive-index transparent layer formed above the transparent electrode; and higher-refractive-index transparent parts embedded in the lower-refractive-index transparent layer and each having a refractive index higher than a refractive index of the lower-refractive-index transparent layer. Each of the higher-refractive-index transparent parts separates light passing through the higher-refractive-index transparent part into zero-order diffracted light, first-order diffracted light, and negative-first-order diffracted light which exit the higher-refractive-index transparent part and travel toward the photoelectric conversion film.