Dual-Substrate Image Sensor for Wider Voltage Bias Control
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Solution Overview
Problem
Current CMOS image sensors have limited operation voltage ranges and lack flexibility in operation, which restricts their performance and functionality.
Innovation Solution
The design includes a dual-substrate structure with a first substrate having unit pixel regions with device and pixel isolation patterns, impurity regions, and a second substrate with a separate body contact, allowing for independent voltage application to each substrate, thereby increasing the operation voltage range and operational freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single-substrate CMOS image sensor structure is used, then the manufacturing process is simple, but the operation voltage range is limited and operational flexibility is reduced
Solution Approach 1:
The image sensor is divided into two separate substrates: a first substrate containing the photoelectric conversion region and a second substrate containing the transistor. This segmentation allows independent voltage application to each substrate through separate ground and body contacts, thereby expanding the operation voltage range and improving operational flexibility without compromising manufacturing feasibility
2Adaptability or versatility
If the ground contact and body contact are electrically connected, then the manufacturing process is simplified, but the voltage range and operational freedom are limited
Solution Approach 1:
The electrical connection between ground and body contacts is segmented into separate paths. The ground contact is coupled to the first substrate while the body contact is coupled to the second substrate, allowing independent voltage control. This segmentation enables flexible voltage operation modes (e.g., separate ground potentials, body biasing) that improve operational freedom
3Adaptability or versatility
If a dual-substrate structure with separated contacts is implemented, then the operation voltage range increases, but the device complexity increases
Solution Approach 1:
The contact configuration is segmented into ground contacts on the first substrate and body contacts on the second substrate. This segmentation naturally accommodates the dual-substrate structure and enables independent voltage application, achieving the desired voltage range expansion while keeping the contact configuration manageable through systematic placement
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 enhances the voltage range and operational flexibility of transistors, improving the image sensor's performance by preventing dark current and enhancing electric characteristics.
Implementation Method 1
Each of the unit pixel regions includes a photodiode, which is used to convert an incident light to an electric signal
Data Source
AI summary
An image sensor may include a first substrate having first and second surfaces and including unit pixel regions, each of which includes a device isolation pattern and a photoelectric conversion region adjacent to the first surface of the first substrate, a pixel isolation pattern provided in the first substrate to define the unit pixel regions and to penetrate the device isolation pattern, a first impurity region and a floating diffusion region provided in the first substrate and adjacent to the first surface, a second substrate provided on the first substrate to have third and fourth surfaces, a second impurity region provided in the second substrate and adjacent to the third surface, and ground and body contacts coupled to the first and second impurity regions, respectively. The ground contact and the body contact may be electrically separated from each other.