Stacked Image Sensor Pixel Circuit With Oxide Semiconductor Amplifier
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Solution Overview
Problem
Conventional image sensors face challenges in efficiently outputting and transferring pixel signals while maintaining low manufacturing costs, due to inadequate configurations and positions of pixel transistors and wires, leading to reduced sensitivity and increased costs.
Innovation Solution
A solid-state imaging element with a semiconductor substrate, a first photoelectric conversion unit, and a control unit including oxide semiconductor pixel transistors, where the channel formation region of the amplification transistor is made of an oxide semiconductor layer, and a manufacturing method involving the formation of oxide semiconductor layers, gate electrodes, power supply wiring, drive wiring, and photoelectric conversion films to optimize signal output and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional pixel transistor configurations are used, then manufacturing processes are simpler, but signal output efficiency is reduced and manufacturing costs increase
Solution Approach 1:
The patent transitions from planar transistor configurations to vertically stacked three-dimensional transistor structures. This dimensional change allows multiple transistors to be integrated in a compact vertical space, improving signal output efficiency while maintaining manageable device complexity through systematic stacking arrangements.
Solution Approach 2:
The patent implements nested transistor structures where transistors are stacked one on top of another, with upper transistors positioned directly above lower transistors. This nesting approach allows efficient space utilization and improved signal transfer pathways, enhancing productivity without proportionally increasing manufacturing complexity.
2Productivity
If pixel size is reduced, then device density increases, but sensitivity is lowered and signal-to-noise ratio is reduced
Solution Approach 1:
The patent moves from two-dimensional pixel arrangements to three-dimensional stacked structures. By stacking photoelectric conversion units and transistors vertically, the patent achieves higher device density while maintaining larger effective photoelectric conversion areas, thereby preserving signal-to-noise ratio despite reduced individual pixel footprints.
Solution Approach 2:
The patent employs composite structures combining multiple photoelectric conversion units with different spectral responses (red, green, blue detecting units) stacked vertically. This composite approach allows each unit to capture its optimal wavelength range, maintaining high sensitivity and signal quality while achieving increased overall device density.
3Adaptability or versatility
If color filters are used in each pixel, then color detection is enabled, but light loss occurs and pixel sensitivity is reduced
Solution Approach 1:
The patent replaces planar color filter arrangements with vertically stacked photoelectric conversion units, each optimized for specific wavelength ranges. This vertical stacking eliminates the need for light to pass through multiple filter layers, reducing light loss while maintaining full color detection capability through direct photoelectric conversion in each stacked unit.
Solution Approach 2:
The patent extracts the color filtering function from traditional planar filter layers and replaces it with wavelength-selective photoelectric conversion units stacked vertically. Each unit directly converts specific wavelength ranges to electrical signals, eliminating the light absorption losses inherent in filter-based systems while preserving color discrimination capabilities.
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
The solution enables efficient output and transfer of pixel signals while suppressing manufacturing costs, improving sensitivity and reducing color sensitivity differences.
Implementation Method 1
a first photoelectric conversion unit provided on the semiconductor substrate; the first photoelectric conversion unit includes a second electrode, a first photoelectric conversion film provided above the second electrode and converting light into charges
Implementation Method 2
a first photoelectric conversion film provided above the second electrode and converting light into charges
Data Source
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AI summary
A solid-state imaging element with pixel transistors and wires capable of efficiently outputting and transferring a pixel signal from a stacked photoelectric conversion film while suppressing an increase in manufacturing cost, and a manufacturing method thereof are provided. There is provided a solid-state imaging element which includes a semiconductor substrate; a first photoelectric conversion unit provided on the semiconductor substrate; and a control unit provided so as to be stacked with the first photoelectric conversion unit and including a plurality of pixel transistors for controlling the first photoelectric conversion unit, in which the first photoelectric conversion unit includes a second electrode, a first photoelectric conversion film provided above the second electrode and converting light into charges, and a first electrode provided on the first photoelectric conversion film, the plurality of pixel transistors include an amplification transistor that amplifies and outputs the charges as a pixel signal, and a channel formation region of the amplification transistor is made of an oxide semiconductor layer.