Image Sensor Protective Layer for Sub-Pixel Crosstalk Reduction
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Solution Overview
Problem
Current image sensors face challenges in achieving optimal optical characteristics and manufacturing methods that enhance light receiving efficiency and signal-to-noise ratio (SNR) due to limitations in pixel isolation and light management structures.
Innovation Solution
The image sensor design incorporates a semiconductor substrate with a grid structure and color filters, where a low-refractive index pattern with pores is used to define sub-pixel regions, and a protective layer made of silicon oxide or nitrogen is applied to cover the grid structure and color filters, improving light distribution and reducing crosstalk between sub-pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a grid structure is used to define sub-pixel regions, then pixel isolation is improved, but light receiving efficiency deteriorates due to increased light loss at boundaries
Solution Approach 1:
The patent applies porous low-refractive index material to fill the grid structure defining sub-pixel regions. The pores in this material reduce light reflection and refraction at the boundaries between adjacent sub-pixel regions, allowing more light to reach the photoelectric conversion regions while maintaining effective pixel isolation. This resolves the contradiction by using a material with specific physical properties (porosity and low refractive index) that simultaneously improves isolation and light receiving efficiency.
2Ease of manufacture
If conventional protective layers are applied, then manufacturing simplicity is maintained, but optical characteristics deteriorate due to light reflection and refraction
Solution Approach 1:
The patent changes the refractive index parameter of the protective layer by using porous low-refractive index material. This material has a refractive index closer to that of air, which reduces the refractive index difference at interfaces and minimizes light reflection and refraction. The protective layer maintains its protective function while improving optical characteristics through this parameter change, resolving the contradiction between manufacturing simplicity and optical performance.
3Object-generated harmful factors
If pixel isolation structures are added to define sub-pixel regions, then crosstalk reduction is achieved, but light management efficiency deteriorates due to increased light loss
Solution Approach 1:
The patent uses a composite structure combining porous low-refractive index material with the grid structure defining sub-pixel regions. This composite material approach creates an optical pathway that maintains effective isolation between pixels while reducing light loss at boundaries. The porous structure with specific refractive index properties allows the system to simultaneously achieve crosstalk reduction and improved light management efficiency, resolving the energy loss contradiction.
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
This configuration enhances light receiving efficiency and improves the signal-to-noise ratio (SNR) by optimizing light incidence and reducing crosstalk, leading to improved optical characteristics and manufacturing efficiency.
Implementation Method 1
A low-refractive index pattern having a low-refractive index region having pores is disposed in the planarization insulating layer
Implementation Method 2
improving light distribution and reducing crosstalk between sub-pixel regions
Data Source
AI summary
An image sensor includes a semiconductor substrate having a plurality of pixel regions arranged in a first direction and a second direction that are parallel to an upper surface of the semiconductor substrate. The first direction is perpendicular to the second direction. A grid structure extends in the first direction and the second direction on the semiconductor substrate to define openings corresponding to a plurality of sub-pixel regions of the plurality of the pixel regions, respectively. Color filters are disposed in the openings of the grid structure, respectively. A protective layer covers sidewalls of the grid structure and bottom surfaces of the color filters. The protective layer includes silicon oxide including carbon (C) or nitrogen (N).