Image Sensor Shared Extrinsic Region for Small-Pixel Noise Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image sensors face challenges in properly sensing light due to increased integration, leading to noise and reduced optical characteristics, especially as demands for high-resolution images with smaller pixel sizes grow.
Innovation Solution
The design of an image sensor that includes a substrate with photodiodes, a pixel separating pattern, and active patterns that overlap photodiodes, allowing for a shared extrinsic region between selection gates and source follower gates, potentially improving optical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel sizes are down-sized to meet high-resolution demands, then the number of pixels increases, but light sensing capability deteriorates and noise increases
Solution Approach 1:
The patent merges the extrinsic regions of the selection transistor and source follower transistor into a shared region. This consolidation reduces the total area occupied by transistor components, thereby compensating for the reduced light sensing area in downsized pixels while maintaining electrical performance
Solution Approach 2:
The shared extrinsic region serves dual purposes: it functions as the extrinsic region for both the selection transistor and the source follower transistor. This multi-functionality reduces redundant structures and improves light sensing efficiency in compact pixel designs
2Productivity
If pixel sizes are reduced, then integration increases, but noise between elements increases
Solution Approach 1:
The patent extracts and removes unnecessary portions of the pixel separating pattern between adjacent photodiodes. By selectively removing these separating structures, the design reduces interference and noise between elements while maintaining adequate isolation, thus improving signal quality in high-integration configurations
3Adaptability or versatility
If additional functions are added to pixels, then functionality increases, but pixel size reduction becomes more constrained
Solution Approach 1:
The patent combines multiple transistor functions into a shared extrinsic region, reducing the area required for additional circuit functions. This enables the inclusion of multiple functions (selection, source follower, reset, etc.) within compact pixel sizes by eliminating redundant structural elements
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 potentially improves the optical characteristics and electric characteristics of the source follower transistor, addressing noise and integration issues in CMOS image sensors.
Implementation Method 1
the photodiode may generate an electrical signal that may vary according to an amount of incident light
Data Source
AI summary
An image sensor includes a substrate, a plurality of photodiodes in the substrate, a pixel separating pattern in the substrate separating the plurality of photodiodes, a first active pattern in the substrate at least partially overlapping a first photodiode and a second photodiode from among the plurality of photodiodes, a selection gate on the first active pattern at least partially overlapping the first photodiode, and a source follower gate on the first active pattern at least partially overlapping the second photodiode. The first photodiode is adjacent to the second photodiode. The pixel separating pattern includes a first pixel separating pattern and a second pixel separating pattern disposed between the first photodiode and the second photodiode. The first pixel separating pattern is spaced from the second pixel separating pattern. The first active pattern includes a first extrinsic region disposed between the first pixel separating pattern and the second pixel separating pattern.