Nanowire Image Sensor Structure for Smaller RGB Pixels
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Solution Overview
Problem
Current image sensors have a large pixel area and an unbalanced energy proportion for red, green, and blue (RGB) light sensing, which affects their efficiency and performance.
Innovation Solution
The image sensor structure incorporates a nanowire structure with sequentially stacked doped layers of different conductive types, allowing for vertically stacked image sensing devices to sense red, green, and blue light, reducing pixel area and achieving a balanced energy proportion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If horizontally arranged image sensing devices are used, then the device structure is simple, but the pixel area becomes large and RGB energy proportion becomes unbalanced
Solution Approach 1:
The patent transitions from horizontal arrangement to vertical stacking of image sensing devices, utilizing the third dimension (depth/vertical space) to pack multiple photodiodes within a smaller pixel footprint. This dimensional change allows multiple color channels (RGB) to be sensed vertically rather than horizontally, reducing pixel area while maintaining device functionality.
Solution Approach 2:
The pixel is segmented into multiple vertically stacked photodiodes, each responsible for sensing specific color wavelengths. This segmentation allows independent optimization of each photodiode's function and enables more efficient use of the pixel area by dividing the sensing function across multiple vertical layers rather than requiring horizontal space for all color channels.
2Ease of manufacture
If horizontally arranged image sensing devices are used, then the manufacturing process is straightforward, but the RGB energy proportion becomes unbalanced
Solution Approach 1:
Each photodiode in the vertical stack is engineered with specific local properties - different depths, doping concentrations, and material compositions optimized for sensing particular wavelength ranges. This local quality differentiation within the vertical stack enables balanced RGB energy proportion by assigning each layer specialized sensing capabilities, whereas horizontal arrangement treats all photodiodes more uniformly.
Solution Approach 2:
The patent employs parameter changes in the vertical stacking configuration, varying parameters such as photodiode depth, doping concentration, and material composition across the vertical layers to optimize sensing efficiency for different colors. These parameter variations enable balanced energy proportion capture, whereas horizontal arrangements typically use more uniform parameter sets across all photodiodes.
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 effectively reduces pixel area and balances the energy proportion of RGB, enhancing the image sensor's performance and eliminating the need for color filters, thereby simplifying the manufacturing process and reducing costs.
Implementation Method 1
The first doped layer and the second doped layer may form a first image sensing device. The second doped layer and the third doped layer may form a second image sensing device. The third doped layer and the fourth doped layer form a third image sensing device.
Data Source
AI summary
An image sensor structure including a substrate, a nanowire structure, a first conductive line, a second conductive line, and a third conductive line is provided. The nanowire structure includes a first doped layer, a second doped layer, a third doped layer, and a fourth doped layer sequentially stacked on the substrate. The first doped layer and the third doped layer have a first conductive type. The second doped layer and the fourth doped layer have a second conductive type. The first conductive line is connected to a sidewall of the second doped layer. The second conductive line is connected to a sidewall of the third doped layer. The third conductive line is connected to the fourth doped layer.