Vertical-Gate Image Sensor for Low-Voltage Photon Counting
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Solution Overview
Problem
Current image sensors face challenges in miniaturization and low-voltage operation while maintaining photon counting capability, which is essential for advanced applications like 3D and color imaging.
Innovation Solution
The design incorporates a semiconductor substrate with a vertical gate electrode, charge pocket region, and impurity regions, along with micro-lenses, to enable efficient photon detection and counting at low voltages, allowing for miniaturization and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional image sensor design is used, then device can operate at standard voltages, but device cannot achieve miniaturization and has high power consumption
Solution Approach 1:
The patent changes the operating voltage parameter from standard voltage to low voltage (e.g., 1.8V or lower), enabling the image sensor to consume less power while maintaining functionality. This parameter change allows the device to be used in applications requiring low power consumption and miniaturization, such as mobile devices and wearable technology.
2Use of energy by moving object
If low voltage operation is implemented, then power consumption is reduced and miniaturization is enabled, but photon counting capability may be compromised
Solution Approach 1:
The patent replaces conventional photodetector mechanisms with a photodiode coupled to a transistor-based readout system. This substitution enables the system to achieve photon counting capability through electrical signal processing rather than relying on high-voltage avalanche processes, thereby maintaining measurement precision at low operating voltages.
3Measurement precision
If photodetector and pixel transistor design is used for single photon counting, then photon detection precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the photodetector and pixel transistor into an integrated pixel structure where the photodiode is directly coupled to the transistor. This merging approach enables single photon counting functionality while minimizing the number of separate components, thereby reducing overall device complexity compared to using entirely separate photodetector and readout circuits.
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 allows for effective photon counting at low voltages, enhancing the image sensor's performance and enabling miniaturization, thus improving low-illuminance performance and reducing the size of the sensor, particularly for Time-of-Flight (TOF) applications.
Implementation Method 1
utilizing a photodiode and MOS transistor with a charge pocket region and vertical gate electrode structure to detect photons by sensing voltage or current changes
Data Source
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AI summary
An image sensor includes a semiconductor substrate including a pixel region; a vertical gate electrode disposed in the semiconductor substrate at a center of the pixel region; a charge pocket region provided under the vertical gate electrode in the semiconductor substrate, and doped with a first impurity having a first conductivity type; a first impurity region which is spaced apart from the charge pocket region in a vertical direction, doped with a second impurity having a second conductivity type, and surrounded by the vertical gate electrode; and a second impurity region which is provided around the vertical gate electrode and doped with the second impurity.