Optical Device Grating Structure for NIR Sensitivity and Crosstalk Reduction
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Solution Overview
Problem
Existing optical devices face challenges in enhancing near-infrared (NIR) sensitivity while maintaining visible image quality, as IR-pass filters in pixels often lead to lateral crosstalk, degrading visible image quality.
Innovation Solution
An optical device with IR-cut and IR-pass pixels, featuring a grating structure with specific dimensions (pitch and height) that reduces IR light penetration and increases reflectivity in IR-cut pixels, and traps IR light in IR-pass filters using low-refractive-index organic materials, combined with a color-filter mosaic pattern and weighting factor matrix for improved light-splitting and realistic color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IR-pass filters are arranged in pixels to enhance NIR sensitivity, then NIR sensitivity is improved, but lateral crosstalk increases and visible image quality deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of different pixel regions. IR-cut pixels are equipped with IR-cut filters and grating structures to reflect IR light, while IR-pass pixels use IR-pass filters to transmit IR light. This localized differentiation allows each pixel type to perform its specific function optimally, enhancing NIR sensitivity in IR-pass pixels while preventing crosstalk in IR-cut pixels.
Solution Approach 2:
The patent segments the image sensor into two distinct types of pixels: IR-cut pixels and IR-pass pixels. Each segment serves a specific function - IR-cut pixels capture visible light while blocking IR light, and IR-pass pixels capture both visible and IR light. This segmentation eliminates the need for all pixels to have the same filter configuration, thereby reducing lateral crosstalk while maintaining enhanced NIR sensitivity in the IR-pass segment.
2Object-affected harmful factors
If grating structure with specific pitch and height is used in IR-cut pixels, then IR light reflectivity is improved and penetration is reduced, but device complexity increases
Solution Approach 1:
The patent employs parameter changes by optimizing the pitch and height of the grating structure to specific ranges (pitch: 0.1-0.7 μm, height: 0.05-0.5 μm) to achieve effective IR light reflection. By carefully selecting these parameters, the grating structure becomes highly efficient at reflecting IR light while maintaining compatibility with standard semiconductor fabrication processes, thus balancing performance improvement with manageable device complexity.
Solution Approach 2:
The patent replaces traditional bulk IR-cut filters with a grating structure that uses diffraction and resonance effects to achieve IR light reflection. This substitution allows for thinner, more integrated structures that can be fabricated using standard semiconductor processes, reducing overall device complexity while maintaining or improving IR light blocking performance.
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 reduces crosstalk, enhances NIR sensitivity, and ensures accurate reproduction of red, green, and blue light information, resulting in improved image quality with realistic color representation.
Implementation Method 1
the pitch is defined by λ/sin θ, wherein λ is a wavelength of an incident light, and θ is a diffraction angle of the incident light through the first grating structure
Implementation Method 2
When IR light enters the grating structure, the IR light forms a resonance (wave-guide) mode within the grating structure and then reflects out the IR-cut pixel
Implementation Method 3
traps IR light in IR-pass filters using low-refractive-index organic materials
Data Source
AI summary
An optical device is provided. The optical device includes a plurality of IR-cut pixels, a plurality of IR-pass pixels, and a plurality of grids. The grids surround the IR-cut pixels and the IR-pass pixels. Each IR-cut pixel includes a first grating structure. A method for fabricating the optical device is also provided.