TFT Array Substrate for X-ray Detector Fill Factor
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Solution Overview
Problem
The fill factor of X-ray detectors is limited due to the occupation of space by components, reducing the area available for the photosensitive surface, which in turn decreases the sensitivity of the detector.
Innovation Solution
A thin film transistor (TFT) array substrate is designed with wires arranged in specific layers to minimize noise and maximize the photodiode area, allowing for improved fill factor and increased photosensitivity by separating and optimizing the placement of wires and transistors within the detector's pixel areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wires are placed in the lower portion of the photodiode layer, then noise is reduced, but the photodiode area is reduced
Solution Approach 1:
The patent applies dimensional change by moving the first wire from the lower portion of the photodiode layer to the upper portion, effectively utilizing the vertical dimension (layer stacking) to resolve the spatial conflict between noise reduction and area maximization. This allows the photodiode to occupy the lower area while the wire occupies the upper layer, eliminating the trade-off.
Solution Approach 2:
The patent implements nesting by placing the first wire within the vertical structure of the photodiode layer (in the upper portion) rather than having it occupy horizontal space at the lower level. This nested arrangement in the vertical dimension allows both components to coexist without reducing the photodiode's active area.
2Measurement precision
If the photodiode area is increased, then sensitivity is improved, but the fill factor is reduced due to component occupation
Solution Approach 1:
The patent resolves the fill factor contradiction by transitioning wire placement to the vertical dimension (upper portion of photodiode layer), freeing up horizontal space in the lower layer. This enables the photodiode to expand its area without being constrained by wire occupation, thereby improving both sensitivity and fill factor simultaneously.
Solution Approach 2:
The patent segments the detector structure into distinct vertical layers, with the photodiode occupying the lower portion and the first wire occupying the upper portion. This segmentation in the vertical dimension allows independent optimization of each component's area without mutual interference, resolving the fill factor limitation.
3Ease of manufacture
If wires are arranged in a single layer, then manufacturing is simplified, but noise increases and photodiode area is reduced
Solution Approach 1:
The patent introduces a second layer dimension for wire arrangement, placing the first wire in the upper portion of the photodiode layer. This multi-layer approach maintains manufacturing simplicity while effectively reducing noise and maximizing photodiode area by eliminating spatial overlap between wires and the photodiode active region.
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 enhances the fill factor of the X-ray detector, increasing the photosensitive area and improving the detector's sensitivity by reducing noise and allowing for a larger photodiode area, thereby enhancing the detection efficiency.
Implementation Method 1
a photodiode formed in a photodiode area... a photodiode generating an electrical detection signal corresponding to incident light
Data Source
AI summary
A thin film transistor (TFT) array substrate for an X-ray detector that improves a fill factor is disclosed. According to one aspect, the substrate includes a plurality of pixel areas each including a transistor area in which a TFT is formed, and a photodiode area in which a photodiode is formed. A first wire is formed in a first layer disposed in a lower portion of a photodiode layer in which the photodiode is formed, in at least a portion of the transistor area of the photodiode layer, and in a second layer disposed in an upper portion of the photodiode layer. A second wire, insulated from the first wire, extends in the pixel areas and is formed in the second layer. At least one TFT is formed in the transistor area and electrically connected to at least one of the first and second wires.