Dielectric Multilayer Color Filter for Solid-State Imaging
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Solution Overview
Problem
Conventional solid-state imaging devices face issues with color separation function degradation due to oblique light and noise, and reducing pigment particle size leads to sensitivity and color unevenness, while existing manufacturing methods are complex and costly.
Innovation Solution
A solid-state imaging device with a filter unit comprising two λ/4 multilayer films and an insulation layer, where each λ/4 multilayer film includes dielectric layers with different refractive indices, and the insulation layer's optical thickness is optimized to transmit specific wavelengths, preventing oblique light from reaching adjacent pixels and improving color separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If pigment particles in color filters are reduced in size to improve resolution, then pixel size can be reduced, but sensitivity and color uniformity deteriorate
Solution Approach 1:
The patent replaces the conventional pigment-based color filter (mechanical/chemical system) with a dielectric multilayer film system that uses optical interference effects. This substitution eliminates the need for pigment particles, allowing for smaller pixel sizes without compromising color uniformity or sensitivity, as the multilayer structure provides consistent optical properties across the pixel area.
Solution Approach 2:
The patent employs composite dielectric multilayer structures with alternating high and low refractive index materials. This composite approach enables precise control of optical transmission characteristics while maintaining color uniformity, resolving the contradiction between miniaturization and color quality.
2Ease of manufacture
If conventional color filters with pigment particles are used, then manufacturing is simpler, but oblique light causes color separation degradation and noise
Solution Approach 1:
The patent replaces pigment-based color filters with dielectric multilayer films that utilize optical interference principles. This substitution creates a structure inherently resistant to oblique light effects, as the multilayer design maintains consistent optical path differences regardless of incident angle, thereby preserving color separation accuracy without complicating the manufacturing process.
Solution Approach 2:
The patent optimizes the optical thickness of each dielectric layer to achieve wavelength-selective transmission. By carefully controlling layer thickness parameters, the filter maintains effective color separation for both perpendicular and oblique incident light, resolving the reliability issue while keeping manufacturing feasible.
3Reliability
If filter thickness is reduced to improve resolution and reduce oblique light effects, then color separation improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses composite dielectric multilayer structures where the combined effect of multiple layers provides robust color separation. This approach allows for moderate individual layer thickness tolerances while maintaining overall filter performance, as the interference pattern emerges from the cumulative effect of all layers rather than depending critically on any single layer's exact thickness.
Solution Approach 2:
The patent divides the color filtering function across multiple dielectric layers rather than relying on a single thick layer. This segmentation allows each layer to contribute to the overall optical effect, providing tolerance to individual layer variations and reducing the cumulative impact of manufacturing precision errors while maintaining effective color separation.
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 enhances color separation and wavelength sensitivity, reduces noise, and simplifies the manufacturing process by allowing for a smaller filter thickness and stable color separation characteristics, while reducing manufacturing costs and complexity.
Implementation Method 1
a dielectric multilayer film 406 including a low refractive index material and a high refractive index material which are alternately layered... the dielectric multilayer film 406 having a thickness of not more than a wavelength of light
Data Source
AI summary
A solid-state imaging device includes a color filter that selectively transmits incoming light. The color filter includes two λ/4 multilayer films, and an insulation layer sandwiched between the two λ/4 multilayer films. Here, each of the λ/4 multilayer films is constituted by a plurality of dielectric layers, and the optical thickness of the insulation layer is not λ/4. Since this color filter has a smaller thickness, the solid-state imaging device has a smaller size.