Shared Gate Electrodes for Solid-State Image Sensor Pixel Miniaturization
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Solution Overview
Problem
In solid-state image sensors with miniaturized pixels, the small width of gate electrodes for transfer transistors and the increased area occupied by control wires lead to decreased charge transfer capability, aperture ratio, and sensitivity, particularly when the space between pixels is small.
Innovation Solution
A semiconductor device design where the number of gate electrodes for transfer transistors is fewer than the number of photodiodes, allowing shared gate electrodes to control multiple transfer transistors, reducing the number of control wires and optimizing the layout to maintain charge transfer efficiency and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the pixel is miniaturized to increase pixel density, then the pixel size is reduced, but the gate electrode width becomes small causing decreased charge transfer capability
Solution Approach 1:
Multiple transfer transistors share a common gate electrode, merging the control function into a single structure. This reduces the number of gate electrodes and control wires, thereby increasing the effective width available for charge transfer in each transistor while maintaining compact pixel dimensions.
Solution Approach 2:
A single gate electrode serves multiple transfer transistors simultaneously, making the gate electrode structure universal across multiple photodiodes. This multi-functional approach reduces overall component count and improves space utilization within the miniaturized pixel.
2Area of moving object
If the pixel is miniaturized to increase pixel density, then the pixel size is reduced, but the area occupied by control wires increases causing decreased aperture ratio
Solution Approach 1:
Multiple control functions are merged into a single gate electrode structure, eliminating the need for separate control wires for each transfer transistor. This consolidation significantly reduces the total wire area within the pixel while maintaining full control capability over multiple photodiodes.
Solution Approach 2:
The shared gate electrode performs universal control functions for multiple transfer transistors, replacing what would otherwise require multiple individual control wire paths. This multi-functional design optimizes space utilization and improves the aperture ratio.
3Area of moving object
If the pixel is miniaturized to increase pixel density, then the pixel size is reduced, but the number of components remains high causing decreased sensitivity
Solution Approach 1:
The control structures of multiple transfer transistors are merged into a single gate electrode, reducing the total component count within the pixel. This consolidation increases the effective area available for light-sensitive elements, thereby improving sensitivity.
Solution Approach 2:
The shared gate electrode provides universal control across multiple photodiodes, reducing redundancy in the pixel structure. This efficient use of space allows for larger photodiode areas or improved light-receiving structures, enhancing sensitivity.
Data Source
AI summary
In a semiconductor device in which a plurality of light receiving elements are provided in each of a plurality of pixels that form a solid-state image sensor, a decrease in the performance of the semiconductor device is prevented, the decrease occurring due to an increase in the number of wires. In the pixel having a first photodiode and a second photodiode, a first transfer transistor coupled to the first photodiode and a second transfer transistor coupled to the second photodiode are respectively controlled by the same gate electrode, thereby allowing the number of wires for controlling the first and the second transfer transistors is reduced.