Pixel Grid and Light-Shield Structure 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 design and structure, particularly in minimizing light absorption and cross-talk while optimizing light reception.
Innovation Solution
The image sensor design incorporates a semiconductor layer with a grid pattern and a light-shield pattern, where the grid pattern is thinner than the light-shield pattern, and includes a low-refractive index material to minimize light absorption and enhance light reception, reducing cross-talk and increasing luminance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grid pattern is used to protect against electrostatic discharge, then reliability is improved, but light absorption increases and image quality deteriorates
Solution Approach 1:
The patent applies different thicknesses of the grid pattern in different regions: a first thickness over the first section and a second thickness over the second section. This local variation allows the grid to provide adequate ESD protection while minimizing light absorption in the active imaging region, thus resolving the contradiction between reliability and light absorption.
2Object-affected harmful factors
If a light-shield pattern is used to reduce cross-talk, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent combines the grid pattern and light-shield pattern into a single integrated structure with varying thicknesses. The grid pattern itself serves dual functions: ESD protection and light shielding. By merging these functions into one structure rather than using separate components, the patent reduces device complexity while still achieving cross-talk reduction.
3Reliability
If the grid pattern thickness is increased to improve ESD protection, then reliability is improved, but light absorption increases and luminance efficiency decreases
Solution Approach 1:
The patent implements a thickness gradient in the grid pattern, with different thicknesses in different sections. The first section has a first thickness optimized for ESD protection, while the second section has a second thickness that balances protection with light transmission. This local optimization maintains luminance efficiency while ensuring adequate ESD protection throughout the device.
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 enhances image quality by reducing light absorption and cross-talk, leading to improved luminance efficiency and image reception capabilities.
Implementation Method 1
a low-refractive index pattern is used to refract light, reducing cross-talk and enhancing luminance efficiency
Implementation Method 2
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.