Inorganic Oxide Semiconductor Layer for Charge Transfer in Image Pickup Elements
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Solution Overview
Problem
Conventional stacked image pickup elements face challenges in efficiently transferring electric charges due to complex fabrication steps and limitations in the composition and configuration of semiconductor materials, leading to reduced manufacturing yield and suboptimal photoelectric conversion efficiency.
Innovation Solution
An image pickup element with a photoelectric conversion unit incorporating an inorganic oxide semiconductor material layer with a specific composition of indium, gallium, and tin, optimized to enhance charge transfer characteristics, including a gallium atomic ratio that balances optical gap, mobility, and oxygen deficiency suppression, ensuring efficient charge accumulation and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor materials and structures are used in stacked image pickup elements, then the device can be manufactured with existing processes, but the charge transfer efficiency is insufficient and signal charge delay occurs
Solution Approach 1:
The patent changes the material parameter from conventional semiconductor to inorganic oxide semiconductor, which fundamentally alters the charge transfer characteristics. This material substitution enables both high transfer efficiency and fast transfer speed by exploiting the unique electrical properties of inorganic oxide semiconductors, resolving the contradiction between reliability and productivity in charge transfer.
Solution Approach 2:
The patent employs a composite structure combining inorganic oxide semiconductor layer with conventional semiconductor substrates and electrodes. This composite approach allows the inorganic oxide semiconductor to provide superior charge transfer performance while maintaining compatibility with existing manufacturing processes, thus improving charge transfer efficiency without sacrificing overall device productivity.
2Reliability
If complex fabrication structures are implemented to improve charge accumulation, then charge transfer characteristics improve, but manufacturing yield decreases
Solution Approach 1:
The patent simplifies the fabrication process by changing the semiconductor material parameter to inorganic oxide semiconductor, which inherently provides excellent charge accumulation characteristics. This material change eliminates the need for complex multi-layer structures and extensive fabrication steps, thereby improving manufacturing yield while maintaining superior charge accumulation performance.
Solution Approach 2:
The patent extracts and eliminates unnecessary complex fabrication steps and structures from conventional processes. By using inorganic oxide semiconductor material, the design removes redundant layers and processing steps that do not contribute to charge accumulation, simplifying manufacturing and improving yield while preserving essential charge transfer functionality.
3Measurement precision
If organic semiconductor material is used for photoelectric conversion layer, then specific color photoelectric conversion is achieved, but charge transfer efficiency is limited
Solution Approach 1:
The patent creates a composite structure where organic photoelectric conversion layer is combined with inorganic oxide semiconductor charge transfer layer. The organic material provides wavelength-selective photoelectric conversion with high color accuracy, while the inorganic oxide semiconductor layer handles charge transfer with high efficiency. This composite approach resolves the contradiction by assigning different functional roles to different materials.
Solution Approach 2:
The patent applies local quality by using different materials optimized for different functions within the same device. The organic semiconductor is used specifically where photoelectric conversion and color selectivity are needed, while the inorganic oxide semiconductor is used where charge transfer efficiency is critical. This spatial differentiation of material properties allows both color accuracy and transfer efficiency to be optimized simultaneously.
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 improved charge transfer efficiency and reduced noise in image pickup elements, enhancing the overall performance and manufacturing yield while maintaining a simple configuration, thereby excelling in charge accumulation and transfer characteristics.
Implementation Method 1
a photoelectric conversion unit that contacts the first electrode and is formed above the charge accumulation electrode via an insulation layer
Data Source
AI summary
An image pickup element 10 includes a first electrode 21, a charge accumulation electrode 24 that is arranged apart from the first electrode 21, a photoelectric conversion unit 23 that contacts the first electrode 21 and is formed above the charge accumulation electrode 24 via an insulation layer 82, and a second electrode 22 formed on the photoelectric conversion unit 23. The photoelectric conversion unit 23 includes, from the second-electrode side, a photoelectric conversion layer 23A, and an inorganic oxide semiconductor material layer 23B including InaGabSncOd, and 0.30≤b/(a+b+c)≤0.50 and b≥c are satisfied.