Pixel-Separated Image Sensor Layout With Common Gate Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image sensors face challenges in achieving high integration and performance across various applications, such as digital cameras and medical micro cameras, due to limitations in pixel arrangement and transistor design.
Innovation Solution
The image sensor design includes a substrate with a device isolation layer, active regions with separated pixel regions, photoelectric devices for light conversion, and a microlens on the substrate surface. This design incorporates select transistors and source follower transistors with a common gate electrode, optimizing pixel arrangement and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pixel regions are separated by device isolation layer to improve integration, then device complexity increases, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The pixel array is divided into multiple pixel regions (first pixel region, second pixel region, third pixel region, fourth pixel region) that are physically separated by device isolation layers. Each pixel region contains its own photoelectric device and associated transistors, enabling independent operation and reducing interference between adjacent pixels while maintaining high integration density.
Solution Approach 2:
Different pixel regions are positioned at different distances from the microlens, creating local variations in optical path length. The first and second pixel regions are at a first distance while the third and fourth pixel regions are at a second distance, allowing optimization of light focusing and conversion efficiency for different spatial locations within the same sensor structure.
2Adaptability or versatility
If select transistors and source follower transistors are formed in each pixel region to improve functionality, then device complexity increases, but area per pixel increases
Solution Approach 1:
The select transistor and source follower transistor are merged into a single integrated structure within each pixel region. The select transistor includes a gate electrode, source region, and drain region, while the source follower transistor shares the drain region of the select transistor as its source region, reducing the total transistor area while maintaining full functionality for signal selection and amplification.
Solution Approach 2:
The common source/drain region serves multiple functions: it acts as the drain region for the select transistor and simultaneously as the source region for the source follower transistor. This multi-functional design reduces the number of discrete regions needed while maintaining complete transistor operation capabilities within each pixel region.
3Manufacturing precision
If photoelectric devices are positioned at different distances from microlens to optimize light conversion, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The pixel regions are arranged in a two-dimensional pattern with varying distances from the microlens along different axes. The first and second pixel regions are positioned at a first distance in one direction, while the third and fourth pixel regions are positioned at a second distance in another direction, creating a multi-dimensional spatial arrangement that optimizes optical path variations without requiring complex three-dimensional structures.
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 proposed image sensor achieves higher integration and improved performance by reducing noise through the common gate electrode design and ensuring efficient light conversion across the pixel regions.
Implementation Method 1
Each of the pixels may include a photoelectric device such as a photodiode (PD). The photoelectric device may convert incident light into an electrical signal.
Data Source
AI summary
An image sensor is provided. The image sensor may include a substrate including first and second surfaces opposite to each other, a device isolation layer extending through the substrate and having a surface level with the second surface of the substrate, an active region comprising first and second pixel regions spaced apart and separated from each other by the device isolation layer, a photoelectric device located in the substrate and configured to convert light into electric charges, a microlens on the first surface, a first select transistor and a first source follower transistor in the first pixel region, a second source follower transistor in the second pixel region, a first node between the first select transistor and the first source follower transistor, on the first pixel region, and a second node on one side of the first select transistor on the first pixel region.