Optical Filter Layer Structure for Pixel-Level Spectral Separation
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Solution Overview
Problem
Existing color filter layers in light detection devices, made from resins with added pigments, face challenges in achieving spectral separation due to material properties limiting transmittance and wavelength division.
Innovation Solution
A light detection device with a semiconductor layer and an optical filter layer comprising first and second filter parts per pixel, each with a specific structure including metal films, dielectric films with different refractive indices, and a light absorption film, allowing for spectral separation by varying the thickness ratio of the dielectric films across different filter parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a color filter layer is constituted by a resin to which a pigment is added, then the structure is simple and manufacturing is easy, but spectral separation cannot be achieved due to material properties limiting transmittance
Solution Approach 1:
The optical filter layer is divided into multiple filter parts (first filter part, second filter part, etc.), each with specific dielectric film thickness ratios to achieve different wavelength band transmissions. This segmentation enables spectral separation by assigning different optical functions to different regions of the filter layer.
Solution Approach 2:
Different regions of the optical filter layer are given different local properties through varying dielectric film thickness ratios. The first filter part has a first thickness ratio optimized for one wavelength band, while the second filter part has a second thickness ratio optimized for another wavelength band, achieving spectral separation through localized property variations.
2Manufacturing precision
If the optical filter layer uses a complex multilayer structure with metal films and dielectric films, then spectral separation is achieved, but manufacturing complexity increases
Solution Approach 1:
Multiple functional layers (metal films, dielectric films with different refractive indices, light absorption films) are merged into a single integrated optical filter layer structure. This combining achieves spectral separation through the cooperative optical effects of the merged layers while maintaining a unified manufacturing process.
Solution Approach 2:
The optical filter layer employs composite material structures combining metal films, dielectric films with different refractive indices, and light absorption films. This composite approach enables spectral separation by leveraging the complementary optical properties of different materials working together.
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 enables effective spectral separation of light into various wavelength bands, reducing color mixing and achieving this at a lower cost compared to conventional color filter layers, while also improving adhesion and reducing yield drops due to peeling issues.
Implementation Method 1
a first dielectric film and a second dielectric film which have different refractive indices and which are arranged in a thickness direction of the semiconductor layer side by side
Implementation Method 2
a first dielectric film and a second dielectric film which have different refractive indices
Implementation Method 3
a light absorption film provided between the first dielectric film and the second dielectric film
Data Source
AI summary
A technique for achieving spectral separation. A light detection device includes a semiconductor layer with a photoelectric conversion unit is provided for each of the pixels, and an optical filter layer on a light incident surface side that includes a first filter part and a second filter part for each of the pixels. Each of the first and second filter parts includes: a first metal film on the light incident surface side of the semiconductor layer; a first dielectric film and a second dielectric film having different refractive indices that are arranged in a thickness direction of the semiconductor layer side by side, on a side of the first metal film opposite the semiconductor layer; and a second metal film on a side of the dielectric films opposite the first metal film. A ratio of thicknesses between the dielectric films is different in the different filter parts.