Imaging Panel Organic Film Extraction for TFT Threshold Stability
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Solution Overview
Problem
The existing X-ray sensors with oxide semiconductor thin film transistors experience a shift in threshold voltage due to defect levels formed during X-ray irradiation, leading to unstable operation.
Innovation Solution
An imaging panel design where an organic film is strategically positioned above or below the thin film transistors, with specific areas devoid of the organic film to prevent capture of positive charges by defect levels, thereby minimizing the shift in threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon dioxide (SiO2) is used in the passivation film or insulating film, then the thin film transistor can be formed with standard materials and processes, but defect levels are formed during X-ray irradiation causing threshold voltage shift and unstable operation
Solution Approach 1:
The patent extracts and removes the organic film from the area above the thin film transistor. This extraction eliminates the source of positive charges that would otherwise be captured by defect levels formed in the SiO2 insulating film during X-ray irradiation, thereby preventing threshold voltage shift while maintaining the use of standard SiO2 materials and processes
Solution Approach 2:
The patent applies local quality by creating a non-uniform structure where the organic film is selectively removed only from the area above the thin film transistor, while remaining present in other areas. This localized modification targets the specific region where charge capture causes instability, without affecting other functional areas of the device
2Device complexity
If an organic film is provided above the thin film transistor, then the device structure is complete and protected, but positive charges in the organic film are captured by defect levels during X-ray irradiation causing threshold voltage shift
Solution Approach 1:
The patent extracts the organic film from the critical area above the thin film transistor to eliminate the charge capture problem. The organic film may still be present in other areas of the device, maintaining structural completeness where needed while removing it from the region where it causes instability
Solution Approach 2:
The patent segments the organic film coverage area, distinguishing between regions where the organic film is present and regions where it is removed. This segmentation allows the device to maintain structural benefits of the organic film in non-critical areas while eliminating its harmful effects in the critical TFT 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
The design effectively stabilizes the operation of thin film transistors by reducing the shift in threshold voltage during X-ray irradiation, ensuring consistent performance.
Implementation Method 1
picking up scintillation light obtained by converting X-ray projected from an X-ray source, with use of a scintillator
Implementation Method 2
conversion elements that are provided at the pixels, respectively, for receiving the scintillation light and converting the same into charges
Data Source
AI summary
An imaging panel having a plurality of pixels, for picking up scintillation light obtained by converting X-ray projected from an X-ray source, with use of a scintillator, includes photodiodes, TFTs, and an organic film. The photodiodes are provided at the pixels, respectively, for receiving the scintillation light and converting the same into charges. The TFTs are provided at the pixels, respectively, for reading the charges obtained through the conversion by the photodiodes. In one pixel area of the pixels, an area where the organic film is not provided exists in a layer at an upper position with respect to the TFTs, other than an area where a contact hole CH1 for connecting the photodiode and the drain electrode is provided.