Detection Substrate Electrode Layout Against TFT Hydrogen Diffusion
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Solution Overview
Problem
Traditional X-ray flat panel detectors using amorphous silicon TFTs suffer from low mobility ratio and large intrinsic size, leading to low frame rate and pixel fill rate, while oxide TFTs like a-IGZO improve performance but are susceptible to hydrogen diffusion during passivation layer deposition, affecting stability.
Innovation Solution
A detection substrate is designed with a base substrate, data and gate lines, thin film transistors, and a laminated structure of first electrodes, photoelectric conversion structures, and second electrodes, where the first electrode overlaps with the active layer of the thin film transistor and includes protruding parts to prevent hydrogen diffusion, and bias lines are electrically connected to the second electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxide TFTs like a-IGZO are used to improve mobility ratio and reduce intrinsic size, then frame rate and pixel fill rate are improved, but stability deteriorates due to hydrogen diffusion during passivation layer deposition
Solution Approach 1:
A protective film is introduced as an intermediary layer between the oxide TFT and the passivation layer. This protective film acts as a barrier to prevent hydrogen diffusion from the passivation layer deposition process to the oxide TFT, thereby maintaining the stability of the oxide TFT while allowing the use of high-performance oxide semiconductor materials for improved frame rate and pixel fill rate.
2Reliability
If the first electrode overlaps with the active layer of the thin film transistor, then electrical connection is improved, but hydrogen diffusion to the active layer increases, affecting stability
Solution Approach 1:
The protective film serves as a mediator between the first electrode and the active layer of the thin film transistor. It allows the first electrode to overlap with and electrically connect to the active layer while simultaneously blocking hydrogen diffusion from the passivation layer to the active layer, thus resolving the contradiction between electrical connection and hydrogen protection.
3Reliability
If protruding parts are added to the first electrode to prevent hydrogen diffusion, then stability is improved, but device complexity increases
Solution Approach 1:
The hydrogen diffusion prevention function is extracted from the first electrode structure and assigned to a separate protective film layer. This extraction simplifies the first electrode design by removing the need for complex protruding parts, while the protective film independently provides the hydrogen barrier function, thereby improving stability without increasing overall device complexity.
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 enhances the stability of the thin film transistor and improves the performance of the flat panel detector by preventing hydrogen diffusion and reducing leakage current, thereby increasing frame rate and pixel fill rate.
Implementation Method 1
a photoelectric conversion layer (120) on the side of the first electrode (110) distant from the base substrate (100)
Data Source
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AI summary
The embodiments of the present disclosure provide a detection substrate, a preparation method thereof and a flat panel detector. An orthographic projection of a first electrode on the base substrate is set to be at least partially overlapped with an orthographic projection of an active layer of a thin film transistor on the base substrate, a first protruding part is arranged on a side, close to a corresponding data line, of the first electrode, an orthographic projection of the first protruding part on the base substrate is located between the orthographic projection of the active layer on the base substrate and an orthographic projection of the data line on the base substrate, thereby preventing hydrogen from diffusing to the active layer in the subsequent process of manufacturing the photoelectric conversion structure, effectively improving the stability of the thin film transistor, and improving the performance of the flat panel detector.