Pixel Grid Structure for Oblique Light Control in Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in enhancing sensitivity and signal-to-noise ratio due to limitations in light collection efficiency, particularly in preventing oblique light from interfering with adjacent pixel regions and effectively utilizing incident light.
Innovation Solution
The implementation of a grid pattern with a lattice shape over the substrate, which overlaps the device isolation layer but is spaced apart from photoelectric conversion devices, enhances light collection by reflecting oblique incident light and minimizing optical dead zones, thereby improving sensitivity and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a grid pattern is introduced to reflect oblique light and reduce optical dead zones, then sensitivity and signal-to-noise ratio are improved, but device complexity increases
Solution Approach 1:
A grid pattern comprising alternating first and second patterns is introduced as an intermediary structure between incident light and the pixel regions. This grid pattern reflects oblique light toward the pixel regions while maintaining compatibility with existing photoelectric conversion devices, thereby improving sensitivity without requiring fundamental changes to the core imaging architecture.
Solution Approach 2:
The grid pattern is configured with specific width ratios (first pattern width to second pattern width between 1:4 and 4:1) and spatial arrangements that utilize optical dimensionality to redirect light paths. By controlling the geometric dimensions and spacing of the grid elements, oblique light from multiple angles is reflected effectively onto the pixel regions, enhancing light collection efficiency.
2Productivity
If the grid pattern width is reduced to minimize optical dead zones, then light collection efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The grid pattern dimensions are optimized within specific parameter ranges: the width ratio between first and second patterns is controlled between 1:4 and 4:1, and the overall grid pattern width is set between 1/10 to 1/5 of the pixel region width. These parameter specifications balance light collection efficiency with manufacturability, ensuring that the grid structure remains effective while accommodating standard fabrication tolerances.
3Object-affected harmful factors
If the grid pattern overlaps the device isolation layer to prevent oblique light interference, then pixel region isolation is improved, but light transmission to pixel regions decreases
Solution Approach 1:
The grid pattern, positioned to overlap the device isolation layer, converts potentially harmful oblique light that would otherwise cause interference or stray light between adjacent pixels into beneficial reflected light. By strategically placing the grid pattern with appropriate width ratios, oblique incident light is reflected onto the pixel regions, transforming what would be a harmful effect into a light-collection enhancement mechanism.
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 increases the amount of incident light received by pixel regions, leading to enhanced sensitivity and signal-to-noise ratio in image sensors, addressing the limitations of existing technologies.
Implementation Method 1
enhances light collection by reflecting oblique incident light
Data Source
AI summary
An image sensor includes a device isolation layer disposed in a substrate and defining pixel regions, and a grid pattern on a surface of the substrate. The grid pattern overlaps the device isolation layer between adjacent pixel regions in a direction perpendicular to the surface. The grid pattern has a width less than a width of the device isolation layer.