Double Gate Thin Film Transistor Substrate Parasitic Capacitance Reduction
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Solution Overview
Problem
The double gate thin film transistor substrate generates parasitic capacitance between the upper and lower gate electrodes, leading to degraded picture quality in organic light-emitting display apparatus due to overlapping areas, which affects the performance of thin film transistors.
Innovation Solution
A thin film transistor substrate design with a lower gate electrode and an upper gate electrode, where at least one of the electrodes is perforated with a through hole to reduce overlapping areas, and the electrodes are independently controlled to minimize parasitic capacitance, using materials like indium gallium zinc oxide (IGZO) for the semiconductor layer and metals for the electrodes to prevent light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double gate electrode structure is used in the thin film transistor, then the control over threshold voltage is improved, but parasitic capacitance is generated between the upper and lower gate electrodes, degrading picture quality
Solution Approach 1:
The gate electrode is divided into two separate gates (upper gate and lower gate) positioned on opposite sides of the semiconductor layer. This segmentation allows independent voltage control of each gate, improving threshold voltage control while the through-holes in each gate reduce overlapping area and parasitic capacitance between the gates
Solution Approach 2:
Through-holes are formed in the upper gate electrode and/or lower gate electrode, creating a porous structure. This reduces the overlapping area between the upper and lower gates, thereby decreasing parasitic capacitance while maintaining the dual-gate control capability
2Reliability
If the upper gate electrode and lower gate electrode have large overlapping areas, then the transistor control capability is improved, but parasitic capacitance increases, affecting performance
Solution Approach 1:
The gate structure is segmented into upper and lower gates with through-holes, allowing the transistor to maintain control capability through dual-gate operation while reducing parasitic capacitance by minimizing the overlapping area between gates
Solution Approach 2:
The overlapping area between upper and lower gates is changed by introducing through-holes, which reduces the parasitic capacitance parameter while maintaining adequate control capability through independent voltage application to each gate
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 reduced parasitic capacitance improves the characteristics of the thin film transistor, decreasing leakage currents and enhancing the picture quality of the organic light-emitting display apparatus by allowing independent control of electric potentials and preventing light interference with the semiconductor layer.
Implementation Method 1
a parasitic capacitance is generated between an upper gate electrode and a lower gate electrode
Implementation Method 2
the lower gate electrode to prevent light transmitted through the substrate from reaching the semiconductor layer
Data Source
AI summary
A thin film transistor substrate that includes a substrate, a lower gate electrode arranged on the substrate, a semiconductor layer arranged on the substrate and overlapping the lower gate electrode, the semiconductor layer including a channel region interposed between a source region and a drain region, and an upper gate electrode arranged on the substrate and overlapping the semiconductor layer, the upper gate electrode being arranged on an opposite side of the semiconductor layer than the lower gate electrode, wherein at least one of the lower gate electrode and the upper gate electrode is perforated by an aperture to reduce a parasitic capacitance between the upper and lower gate electrodes.