Oxide Semiconductor Pixel Circuit for Low Power Imaging
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Solution Overview
Problem
Imaging devices face challenges in capturing high-quality images under low illuminance, requiring wide dynamic range, high resolution, and low power consumption while maintaining high reliability and being cost-effective, especially in varying temperature conditions.
Innovation Solution
The imaging device incorporates a pixel circuit with a p-channel transistor in a silicon substrate, a photodiode, and n-channel transistors with oxide semiconductor active layers, forming a CMOS circuit for efficient light management and low off-state current, allowing for high-speed operation and wide temperature range usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxide semiconductor transistors are used in pixel circuits, then power consumption is reduced and off-state current is lowered, but manufacturing complexity increases due to multiple material requirements
Solution Approach 1:
The patent merges oxide semiconductor transistors and silicon transistors into a single integrated imaging device, allowing the pixel circuit to use oxide semiconductors for low power consumption while peripheral circuits use silicon for high-speed operation. This combination resolves the contradiction by enabling energy efficiency in critical areas without sacrificing overall device performance or requiring completely separate manufacturing processes.
Solution Approach 2:
The patent applies different semiconductor materials to different functional areas: oxide semiconductors are used specifically in pixel circuits where low off-state current is critical for power savings, while silicon is used in peripheral circuits where high-speed operation is prioritized. This localized application of material properties resolves the contradiction by optimizing each region for its specific functional requirements.
2Productivity
If high integration is achieved, then device functionality is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the imaging device into distinct functional regions with different material requirements - pixel circuits using oxide semiconductors and peripheral circuits using silicon. This segmentation allows each region to be optimized independently, achieving high integration without uniformly increasing manufacturing precision requirements across the entire device.
Solution Approach 2:
The patent creates a multi-functional device structure where a single substrate supports both oxide semiconductor-based pixel circuits and silicon-based peripheral circuits. This universal platform approach enables high integration by accommodating multiple material systems and functional requirements within one device, avoiding the need for separate manufacturing processes for each function.
3Speed
If oxide semiconductor transistors are used, then operating speed is improved, but device area increases reducing aperture ratio
Solution Approach 1:
The patent changes the material parameter from conventional silicon to oxide semiconductor in pixel circuit transistors, which improves operating speed and reduces off-state current. By changing this critical material parameter locally in the pixel circuit area, the patent achieves faster operation without proportionally increasing the overall device area, as the material change enables more efficient circuit design.
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 enables the imaging device to capture images with a wide dynamic range, high resolution, and low power consumption, suitable for low illuminance conditions and varying temperatures, while maintaining a high aperture ratio and reliability.
Implementation Method 1
a photoelectric conversion element formed using silicon
Data Source
AI summary
An image-capturing device which is capable of capturing high quality images and can be formed at a low cost is provided. The image-capturing device includes a first circuit including a first transistor and a second transistor, and a second circuit including a third transistor and a photodiode. The first transistor is provided on a first surface of a silicon substrate. The second transistor is provided over the first transistor. The photodiode is provided to the silicon substrate. The silicon substrate includes a second insulating layer surrounding a side surface of the photodiode. The first transistor is a p-channel transistor including an active region in the silicon substrate. The third transistor is an n-channel transistor including an oxide semiconductor layer as an active layer. A light-receiving surface of the photodiode is a surface of the silicon substrate opposite to the first surface.