TFT Array Metal Layer Segmentation for Noise Reduction
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Solution Overview
Problem
The production yield of TFT arrays in radiation image detectors is hindered by line defects, and the image quality is compromised by electronic noise due to high line capacitance in the data lines.
Innovation Solution
Forming scan lines, data lines, and common lines with distinct metal layers separated by insulating films to reduce line capacitance and improve production yield, while also reducing electronic noise by optimizing the thickness and dielectric constants of the insulating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If scan lines, data lines and storage capacitor lines are formed in the same metal layer, then the manufacturing process is simplified, but line defects occur and production yield decreases
Solution Approach 1:
The patent divides the conductive lines into separate metal layers: scan lines and gate electrodes in one layer, and data lines and storage capacitor lines in another layer. This segmentation prevents line defects caused by overlapping patterns in the same layer, thereby improving production yield while maintaining manufacturing feasibility through standard multi-layer TFT fabrication processes.
2Device complexity
If data lines are formed in the same metal layer as source and drain electrodes, then the device complexity is reduced, but electronic noise increases due to high line capacitance
Solution Approach 1:
The patent resolves the capacitance issue by moving data lines to a different metal layer (second metal layer) separated from source and drain electrodes by an insulating film. This spatial separation in the vertical dimension reduces parasitic capacitance between adjacent conductors, thereby reducing electronic noise while maintaining a relatively simple planar device structure.
3Object-generated harmful factors
If insulating film thickness is increased to reduce line capacitance, then electronic noise decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the insulating film thickness to a specific range (50-200 nm) that balances noise reduction with manufacturing feasibility. This parameter optimization achieves sufficient capacitance reduction without imposing excessive precision requirements on the fabrication process, making the solution practically implementable.
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 approach enhances the production yield of TFT arrays and improves image quality by reducing line capacitance and electronic noise, specifically achieving a 48% reduction in line capacitance and corresponding noise reduction.
Implementation Method 1
electronic noise due to high line capacitance in the data lines
Implementation Method 2
optimizing the thickness and dielectric constants of the insulating films
Data Source
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AI summary
The invention provides an image detector capable of improving the quality of detected images by reducing electronic noise, the image detector comprising, a plurality of scan lines disposed in parallel, a plurality of data lines provided so as to cross with the scan lines, thin film transistors connected with the scan and data lines and provided in matrix, sensor sections connected to the thin film transistor and provided in a matrix and a plurality of common lines disposed so as to apply bias voltage commonly to the sensor sections provided in matrix. Each of the scan lines, data lines and common lines are formed by metal layers different from each other and provided with insulating film(s) disposed therebetween.