Pixel Grid and Light-Shield Layout for Low Cross-Talk Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in achieving improved image quality due to limitations in pixel design and light management, leading to issues with cross-talk and luminance efficiency.
Innovation Solution
The image sensor design incorporates a semiconductor layer with distinct sections, including a grid pattern and a light-shield pattern, where the grid pattern is thinner and made of low-refractive material, minimizing light absorption while allowing electrostatic discharge and refracting light to enhance pixel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shield pattern is used to block light and reduce cross-talk, then cross-talk is reduced, but light absorption increases and luminance efficiency decreases
Solution Approach 1:
The patent applies local quality by using different material properties in different regions: the light-shield pattern uses high-refractive-index material to block light effectively, while the grid pattern uses low-refractive-index material to minimize light absorption. This localized differentiation allows each region to optimize its function without compromising overall performance.
Solution Approach 2:
The patent changes the refractive index parameter of the materials used in different patterns. By selecting materials with appropriate refractive indices (high for light-shield, low for grid), the patent optimizes both light blocking and light transmission properties, resolving the contradiction between reducing cross-talk and maintaining luminance efficiency.
2Reliability
If a thicker grid pattern is used to improve electrostatic discharge protection, then reliability improves, but light absorption increases and image quality deteriorates
Solution Approach 1:
The patent changes the refractive index parameter of the grid pattern material to a low value, which reduces light absorption even when the pattern has sufficient thickness for electrostatic discharge protection. This parameter optimization allows the grid to maintain both protective function and optical performance.
Solution Approach 2:
The patent employs composite material strategy by using different materials with different refractive indices for different functional patterns. The grid pattern uses low-refractive-index material optimized for light transmission, while the light-shield pattern uses high-refractive-index material optimized for light blocking, allowing each component to perform its function optimally.
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 design reduces cross-talk and increases luminance efficiency, resulting in improved image quality by optimizing light management and pixel performance.
Implementation Method 1
the grid pattern is thinner and made of low-refractive material, minimizing light absorption while allowing electrostatic discharge and refracting light to enhance pixel efficiency
Implementation Method 2
Each of the pixels includes a photodiode (PD). The photodiodes serve to transform incident light into an electrical signal.
Data Source
AI summary
An image sensor includes a semiconductor layer including a first section and a second section, the semiconductor layer having a first surface and a second surface that face each other; a device isolation layer in the semiconductor layer and defining a plurality of pixels; a first grid pattern on the first surface of the semiconductor layer over the first section; and a light-shield pattern on the first surface of the semiconductor layer over the second section. A top surface of the first grid pattern is located at a first level, a top surface of the light-shield pattern is located at a second level, the first level is lower than the second level, and the first and second levels are defined with respect to the first surface of the semiconductor layer.