Thin-Film Transistor Substrate With Integrated Capacitive Electrode
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Solution Overview
Problem
Current thin-film transistor (TFT) substrates, particularly those using oxide semiconductor materials like IGZO, face challenges in achieving efficient power management due to small leakage currents, which can impact the performance and energy efficiency of display devices such as OLEDs.
Innovation Solution
The implementation of a thin-film transistor substrate configuration that includes a first and second insulating film, a first and second TFT with top-gate electrodes, and a capacitive element utilizing a low-resistive semiconductor region from the same semiconductor layer, where the low-resistive region overlaps with the top-gate electrode, enabling efficient structure and manufacturing by sharing source/drain regions between TFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional TFT substrate structure is used, then the manufacturing process is simpler, but leakage current is higher and power consumption increases
Solution Approach 1:
The patent merges the storage capacitor electrode with the source/drain electrode of the TFT into a single continuous conductive layer. This integration eliminates the need for separate capacitor electrodes and reduces the number of manufacturing steps while achieving low leakage current through the oxide semiconductor material
Solution Approach 2:
The oxide semiconductor layer serves multiple functions: it acts as the active channel region of the TFT and simultaneously forms the electrode of the storage capacitor. This multi-functional design reduces device complexity while maintaining low leakage current characteristics
2Area of stationary object
If separate capacitor electrodes are used, then the capacitive element can be formed, but the device area increases and manufacturing becomes more complex
Solution Approach 1:
The storage capacitor electrode is merged with the source/drain electrode into a single conductive structure, eliminating the need for separate capacitor electrodes and reducing device area while simplifying the manufacturing process
Solution Approach 2:
The same conductive layer serves dual purposes as both the TFT source/drain electrode and the storage capacitor electrode, reducing the number of manufacturing steps and minimizing device area
3Reliability
If oxide semiconductor material is used, then leakage current is reduced, but the semiconductor layer requires additional processing steps
Solution Approach 1:
The patent controls the resistance of the oxide semiconductor layer by adjusting processing parameters such as oxygen partial pressure during annealing and impurity concentration, achieving low leakage current while maintaining ease of manufacture through parameter optimization rather than additional processing steps
Data Source
AI summary
A thin-film transistor substrate includes a first insulating film, a second insulating film located upper than the first insulating film, a first thin-film transistor, a second thin-film transistor, and a capacitive element. The first thin-film transistor includes a top-gate electrode and a first semiconductor region located above the first insulating film. The second thin-film transistor includes a second semiconductor region located above the second insulating film. The capacitive element includes at least a part of the top-gate electrode and a first low-resistive semiconductor region of the same semiconductor layer that includes the second semiconductor region, the first low-resistive semiconductor region overlapping at least a part of the top-gate electrode with an insulating film interposed therebetween.