Solid-state imaging device reflection ratio adjusting layer
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Solution Overview
Problem
Solid-state imaging devices face challenges in suppressing light reflection across a wide wavelength band due to the difficulty in forming deep uneven structures with pitches smaller than 100 nm, which affects sensitivity and causes flare and ghost issues.
Innovation Solution
A solid-state imaging device with a reflection ratio adjusting layer comprising a first layer with an uneven structure and a second layer of lower refractive index material, where the first layer's thickness is optimized for the received wavelength, reducing reflection by minimizing diffraction and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a deep uneven structure with narrow pitch is formed to suppress light reflection, then reflection suppression is improved, but manufacturing difficulty increases and thickness cannot be kept below 100 nm
Solution Approach 1:
The reflection suppression layer is divided into multiple layers (first layer with uneven structure and second layer with lower refractive index material) to achieve effective reflection suppression without requiring a single deep structure that is difficult to manufacture
Solution Approach 2:
The thickness of the first layer is optimized for the specific wavelength of light to be received, allowing the structure to achieve effective reflection suppression at manageable thicknesses rather than requiring uniformly deep structures across all wavelengths
2Productivity
If pixel size is reduced to increase pixel count, then device integration is improved, but sensitivity deteriorates due to reduced aperture ratio
Solution Approach 1:
A thin-film reflection suppression structure is applied to the pixel surface, providing effective reflection suppression without adding significant thickness, thereby maintaining sensitivity while allowing for reduced pixel sizes
Solution Approach 2:
The reflection suppression layer uses composite structure with different materials (first layer and second layer with different refractive indices) to achieve superior reflection suppression performance, compensating for the reduced light-gathering area in smaller pixels
3Device complexity
If a single-layer uneven structure is used, then structure simplicity is maintained, but reflection suppression effectiveness is insufficient across wide wavelength band
Solution Approach 1:
The solution transitions from a single-layer to a multi-layer structure, adding the dimension of layering to achieve broad-spectrum reflection suppression that cannot be achieved with a single layer, while keeping each individual layer relatively simple
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 light reflection across a wide wavelength band, improving sensitivity and reducing flare and ghost effects, even at smaller pixel sizes.
Implementation Method 1
a recess portion on the uneven structure is filled with a material having a lower refractive index than a refractive index of the substrate forming the second layer
Implementation Method 2
a thickness of the first layer is made a thickness optimized for a wavelength of light to be received
Data Source
AI summary
A substrate includes a photoelectric converting unit in a pixel unit and a reflection ratio adjusting layer provided on the substrate in an incident direction of incident light with respect to the substrate for adjusting reflection of the incident light on the substrate. The reflection ratio adjusting layer includes a first layer formed on the substrate and a second layer formed on the first layer, the first layer has an uneven structure provided on the substrate, and a recess portion on the uneven structure is filled with a material having a lower refractive index than that of the substrate forming the second layer, and a thickness of the first layer is optimized for a wavelength of light to be received. The present technology may be applied to an imaging device.