Multilayer Photodetector Filter Structure for Flare Suppression
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Solution Overview
Problem
Conventional photodetection devices experience flare issues due to light leakage at pixel boundaries, which affect image quality, particularly in devices that detect red, green, and blue light.
Innovation Solution
A photodetection device with a semiconductor layer and a multilayer film filter having a stacked structure of high and low refractive index layers, integrated with the semiconductor layer, where the light incident surface features an uneven shape to scatter light and enhance transmission of a specific wavelength band while reducing flare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light shielding film is provided at pixel boundaries to suppress flare, then flare is reduced, but light transmission in the desired wavelength band is blocked
Solution Approach 1:
The patent applies local quality by making the light shielding film's optical properties position-dependent. The film has different transmittance characteristics for different wavelength bands at different locations: high transmittance for the desired wavelength band (e.g., 400-700nm) and low transmittance for other wavelength bands (e.g., infrared). This allows the same film structure to simultaneously achieve flare suppression and light transmission by selectively filtering wavelengths based on location and direction.
Solution Approach 2:
The patent changes the optical parameters of the light shielding film by controlling its material composition, thickness, and layer structure. By adjusting these parameters, the film achieves wavelength-selective transmittance: it maintains high transmittance for visible light (400-700nm) while blocking infrared light and other unwanted wavelengths. This parameter optimization resolves the contradiction between flare suppression and light transmission.
2Object-affected harmful factors
If a light shielding film is provided at pixel boundaries to suppress flare, then flare is reduced, but image quality deteriorates due to reduced quantum efficiency
Solution Approach 1:
The light shielding film implements local quality by having directionally selective optical properties. It exhibits high transmittance for light incident from the optical system side (forward direction) and low transmittance for light incident from the pixel boundary side (backward direction, which causes flare). This directional selectivity allows the film to maintain high quantum efficiency for useful light while effectively suppressing flare from adjacent pixels.
Solution Approach 2:
The patent optimizes the film's physical parameters including thickness (e.g., 50-200nm), material composition (e.g., silicon oxide, silicon nitride), and layer structure to achieve the desired optical characteristics. These parameter changes enable the film to transmit sufficient light for high quantum efficiency while blocking flare, thus resolving the contradiction between flare suppression and image quality.
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 flare by increasing the transmission of desired wavelengths and reducing the transmission of other wavelengths, thereby improving image quality and quantum efficiency.
Implementation Method 1
the multilayer film filter has a stacked structure in which a high refractive index layer and a low refractive index layer are alternately stacked, and is capable of transmitting light in a first wavelength band at a higher transmittance than light in other wavelength bands
Implementation Method 2
a side of the light incident surface of the photoelectric conversion regions has an uneven shape
Data Source
AI summary
A photodetection device in which flare is suppressed is provided. The photodetection device includes a semiconductor layer in which one surface is a light incident surface and another surface is an element formation surface, the semiconductor layer including a plurality of photoelectric conversion regions arranged in an array along a row direction and a column direction perpendicular to a thickness direction and a multilayer film filter provided integrally with the semiconductor layer on a side of the light incident surface of the semiconductor layer and provided at a position overlapping the photoelectric conversion regions, in which a side of the light incident surface of the photoelectric conversion regions has an uneven shape, and the multilayer film filter has a stacked structure in which a high refractive index layer and a low refractive index layer are alternately stacked, and is capable of transmitting light in a first wavelength band at a higher transmittance than light in other wavelength bands among light incident along the thickness direction.