Image Sensor Vertical Stacking for Multi-Wavelength Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensors require multiple pixels and color filters to detect different wavelength ranges of light, which complicates the design and reduces operational speed.
Innovation Solution
An image sensor design featuring a single pixel with multiple vertically overlapping photoelectric conversion parts and floating diffusion parts, each positioned at specific depths to detect various wavelength ranges, and a single transfer gate that concurrently transfers light signals of different wavelengths, eliminating the need for color filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple pixels and color filters are used to detect different wavelength ranges, then detection capability across various wavelengths is improved, but device complexity and design difficulty increase
Solution Approach 1:
The patent transitions from a two-dimensional pixel array with color filters to a three-dimensional structure by stacking multiple photoelectric conversion parts vertically. Each photoelectric conversion part detects different wavelength ranges, enabling multi-wavelength detection within a single pixel location without requiring multiple pixels or color filters, thus resolving the technical contradiction.
Solution Approach 2:
The patent implements a nested structure where multiple photoelectric conversion parts are vertically stacked and integrated within a single pixel unit. The first, second, and third photoelectric conversion parts are positioned at different depths, with each containing impurity regions that detect specific wavelength ranges, allowing compact integration of multiple detection functions in one location.
2Adaptability or versatility
If multiple pixels and color filters are used to detect different wavelength ranges, then spectral detection range is improved, but operational speed decreases
Solution Approach 1:
The patent merges multiple photoelectric conversion parts and their associated floating diffusion parts into a single integrated structure within one pixel. The first, second, and third photoelectric conversion parts are vertically stacked and share a common transfer gate and readout circuitry, enabling simultaneous detection of multiple wavelengths without the speed penalties of complex multi-pixel systems.
3Adaptability or versatility
If multiple transfer gates are used to handle signals from different wavelength detectors, then signal transfer capability is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal transfer gate structure that handles signals from all three photoelectric conversion parts. The single transfer gate is positioned to overlap with channel regions formed between the vertically stacked floating diffusion parts, enabling it to transfer signals from different wavelength detectors simultaneously, thus providing multi-functionality without increasing structural complexity.
4Measurement precision
If photoelectric conversion parts are positioned at different depths, then wavelength-specific detection is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the photoelectric conversion function into multiple distinct parts positioned at different vertical depths. Each photoelectric conversion part contains impurity regions doped at specific concentrations and depths, with the first part detecting one wavelength range, the second part detecting another range, and the third part detecting a third range, thereby achieving wavelength-specific detection through functional segmentation.
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
Enables simultaneous detection of lights across various wavelength ranges, enhancing operating speed and allowing for high integration without the need for multiple transfer gates or color filters.
Implementation Method 1
The photodiode is typically configured to transform an incident light into an electrical signal
Data Source
AI summary
An image sensor includes a transfer gate including a gate buried portion extending into a semiconductor substrate from a surface of the semiconductor substrate, a plurality of photoelectric conversion parts that are disposed in the semiconductor substrate on a side of the gate buried portion and vertically overlap each other, and a plurality of floating diffusion parts that are apart from and vertically overlap each other in the semiconductor substrate on other side of the gate buried portion, wherein at least one of the floating diffusion parts is positioned at a height of at least one of corresponding photoelectric conversion parts.