Image Sensor Blocking Layer for Hydrogen Penetration
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Solution Overview
Problem
Conventional X-ray image sensors face limitations in signal read-out speed due to high on-state resistance of switching elements and variations in threshold voltages, which affect resolution and dynamic range, and amorphous oxide semiconductors struggle with hydrogen penetration issues affecting stability.
Innovation Solution
An image sensor structure with hydrogenated amorphous silicon photoelectric transducers and amorphous oxide semiconductor switching elements, where a blocking layer, such as SiC, Al2O3, or AlN, is used to prevent hydrogen penetration, improving stability and read-out speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a-Si:H TFTs are used as switching elements, then the structure is simple and manufacturing is easy, but the on-state resistance is high which limits signal read-out speed
Solution Approach 1:
The patent changes the material parameter from a-Si:H to amorphous oxide semiconductor, which fundamentally alters the electrical properties including field-effect mobility and on-state resistance, enabling high-speed signal read-out while maintaining manufacturing simplicity
Solution Approach 2:
The patent uses a composite structure combining amorphous oxide semiconductor layer with hydrogenated amorphous silicon photoelectric transducer layer, where each material contributes its optimal properties to the overall device performance
2Speed
If poly-Si TFTs are used as switching elements, then the on-state resistance is low which improves signal read-out speed, but the threshold voltage varies largely which affects manufacturing precision
Solution Approach 1:
The patent changes the material from poly-Si to amorphous oxide semiconductor, which has inherently lower threshold voltage variation due to its amorphous structure, thereby improving manufacturing precision while maintaining high signal read-out speed
Solution Approach 2:
The patent adopts amorphous oxide semiconductor which can be formed by low-cost sputtering methods, replacing expensive and complex poly-Si formation processes, achieving both high speed and manufacturing precision
3Reliability
If hydrogenated amorphous silicon photoelectric transducers are used, then the quantum efficiency is high, but hydrogen separates from the layer at high temperature which penetrates into the amorphous oxide semiconductor and affects stability
Solution Approach 1:
The patent introduces a blocking layer as an intermediary between the hydrogenated amorphous silicon photoelectric transducer and the amorphous oxide semiconductor switching element, which prevents hydrogen penetration while allowing both materials to maintain their optimal properties
Solution Approach 2:
The patent converts the potential harm of hydrogen separation into a beneficial structure by using the blocking layer to capture and contain the separated hydrogen, preventing it from reaching the amorphous oxide semiconductor and thus maintaining device stability
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 enables high-speed signal read-out from high-resolution image sensors, supports fluoroscopy, and reduces manufacturing variations, enhancing yield and cost-effectiveness.
Implementation Method 1
a blocking layer which suppresses penetration of hydrogen separated from the hydrogenated amorphous silicon layers
Implementation Method 2
converting the light into electric charges with the photoelectric transducers
Data Source
AI summary
Provided are an image sensor and a method of manufacturing method of manufacturing the image sensor. The image sensor includes a substrate, photoelectric transducers and switching elements formed in layers on the substrate in this order. Each of the photoelectric transducers includes a hydrogenated amorphous silicon layer. Each of the switching elements includes an amorphous oxide semiconductor layer. The image sensor further includes a blocking layer arranged between the hydrogenated amorphous silicon layers of the photoelectric transducers and the amorphous oxide semiconductor layers of the switching elements, where the blocking layer suppresses penetration of hydrogen separated from the hydrogenated amorphous silicon layers.