Vertical Transfer Gate Image Sensor for High Integration
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is to create an image sensor with improved performance that can provide high resolution images while maintaining pixel characteristics, as increasing integration density leads to deterioration of pixel characteristics due to reduced physical size.
Innovation Solution
The image sensor design includes a photoelectric conversion element, a vertical transfer gate with through holes, a floating diffusion layer, and a capacitor, along with a channel structure and interlayer dielectric layer, which facilitates high integration and prevents characteristic deterioration by optimizing the structure and materials used, such as low-K and high-K gate dielectric layers, and a method for fabricating these components to enhance integration and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If integration density is increased to provide high resolution images, then resolution is improved, but pixel characteristics deteriorate due to reduced physical size
Solution Approach 1:
The patent transitions from planar pixel arrangement to a three-dimensional stacked architecture where photoelectric conversion elements, transfer gates, and floating diffusion layers are vertically stacked. This vertical integration allows higher pixel density without reducing individual pixel area, thereby maintaining pixel characteristics while improving resolution.
Solution Approach 2:
The patent implements nested structures where the channel structure is formed within through-holes of the transfer gate, and multiple functional layers are stacked within a compact vertical space. This nesting approach maximizes the use of available space while preserving the functional integrity of each component.
2Productivity
If physical size of pixels is reduced to increase integration density, then more pixels can be integrated, but pixel characteristics deteriorate
Solution Approach 1:
The patent moves from two-dimensional pixel scaling to three-dimensional stacking, where multiple functional layers are vertically arranged. This allows integration density to increase through vertical stacking rather than horizontal compression, preserving the physical size and characteristics of individual pixel components.
Solution Approach 2:
The pixel structure is segmented into distinct functional layers (photoelectric conversion element, transfer gate, floating diffusion layer, capacitor) stacked vertically. Each layer can be independently optimized for its specific function while maintaining overall compactness, allowing high integration without compromising individual component performance.
3Measurement precision
If more pixels are integrated in limited area, then resolution is improved, but manufacturing complexity increases
Solution Approach 1:
Multiple functional components (transfer gate, floating diffusion layer, capacitor) are merged into a single vertical stack above each photoelectric conversion element. This consolidation reduces the lateral space required and simplifies the manufacturing process by enabling simultaneous formation of multiple components through vertical deposition and etching processes.
Solution Approach 2:
The patent resolves manufacturing complexity by transitioning to vertical stacking, where complex multi-component structures are formed through sequential layer deposition and through-hole etching rather than complex lateral patterning. This approach simplifies the fabrication process while achieving high pixel density.
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 design enables high integration and maintains pixel characteristics, allowing for improved resolution and efficiency in image sensing, facilitating the integration of more pixels in a limited area without deteriorating their performance.
Implementation Method 1
An image sensor converts an optical image into electrical signals
Data Source
AI summary
Provided is an image sensor having improved characteristics. An image sensor in accordance with an embodiment of the present invention may include a photoelectric conversion element formed in a substrate; a transfer gate formed over the photoelectric conversion element, formed over a first surface of the substrate and having at least one through hole, wherein the through hole passes through the transfer gate; a floating diffusion layer formed over the transfer gate; a channel structure formed in the through hole and electrically coupling the photoelectric conversion element to the floating diffusion layer in response to a signal applied to the transfer gate; and a capacitor formed over the floating diffusion layer.