Flat Panel Detector Substrate Layout to Block TFT Hydrogen Diffusion
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Solution Overview
Problem
Traditional X-ray flat panel detectors using amorphous silicon TFTs suffer from low mobility and stability issues due to hydrogen diffusion during passivation and PIN film layer deposition, affecting the detector's performance.
Innovation Solution
A detection substrate with a base substrate, data lines, gate lines, thin film transistors, and photoelectric conversion structures, where the first electrode overlaps with the active layer of the transistor to prevent hydrogen diffusion, and an insulating layer with specific passivation layers is used to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passivation and PIN film layer deposition are performed using conventional methods, then the manufacturing process is simple, but hydrogen diffusion occurs causing low stability and performance
Solution Approach 1:
The passivation layer is divided into multiple segments: a first passivation layer (silicon nitride) and a second passivation layer (silicon oxide), each serving specific functions. The first layer provides hydrogen barrier properties while the second layer provides electrical insulation, collectively preventing hydrogen diffusion and improving TFT stability without excessive complexity
Solution Approach 2:
The patent employs composite material structure by combining silicon nitride and silicon oxide in a layered configuration. This composite approach leverages the hydrogen barrier properties of silicon nitride and the electrical insulation properties of silicon oxide, achieving both stability improvement and process compatibility
2Reliability
If the first electrode is positioned to overlap with the active layer, then hydrogen diffusion is prevented improving stability, but the device structure becomes more complex
Solution Approach 1:
The first electrode is extended in the vertical dimension to overlap with and cover the active layer of the TFT. This dimensional extension creates a protective configuration that prevents hydrogen diffusion from the passivation layer to the active layer, improving stability while maintaining a relatively simple planar structure
Solution Approach 2:
The first electrode serves as an intermediary barrier between the passivation layer and the active layer. By positioning the electrode to overlap with the active layer, it acts as a physical shield that blocks hydrogen diffusion pathways, thereby protecting the active layer without requiring complex additional structures
3Speed
If conventional TFT structures are used, then manufacturing is easier, but mobility is low and frame rate is limited
Solution Approach 1:
The patent modifies key parameters of the TFT structure: using a bottom-gate configuration with extended source and drain regions, implementing a multi-layer passivation structure, and positioning the first electrode to overlap with the active layer. These parameter changes collectively improve carrier mobility and reduce leakage current, enabling higher frame rates while remaining compatible with existing manufacturing processes
4Measurement precision
If leakage current is not controlled, then manufacturing is simpler, but signal-to-noise ratio deteriorates
Solution Approach 1:
The device is segmented into functionally distinct regions: the first electrode region that overlaps with the active layer to control leakage, the pixel electrode region for signal collection, and the separated anode and cathode regions. This segmentation allows targeted leakage current control at the electrode-active layer interface, improving signal-to-noise ratio without requiring complex additional components
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 improves the stability and performance of the flat panel detector by preventing hydrogen diffusion and reducing leakage current, leading to higher frame rates and pixel fill rates, and enhancing the signal-to-noise ratio.
Implementation Method 1
an orthographic projection of the first electrode on the base substrate at least partially overlaps with an orthographic projection of an active layer of the corresponding thin film transistor on the base substrate
Implementation Method 2
converts the visible light into electrical signals under the effect of the PIN
Data Source
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.