Dual-Gate Oxide TFT Layout for Stable Channel Length
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Solution Overview
Problem
Thin film transistors, particularly oxide semiconductor thin film transistors, face challenges in maintaining uniform effective channel lengths, leading to property deviations and reduced driving stability, which affects the display quality of high-resolution display devices as the number of pixels increases.
Innovation Solution
Incorporating an auxiliary electrode on one side of the active layer opposite to the gate electrode, with specific overlap and spacing configurations, to define an effective channel length and enhance driving stability by applying a voltage higher than the source electrode, thereby forming a double gate structure and minimizing property deviations among transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of pixels is increased to achieve high resolution, then the display quality is improved, but the number of thin film transistors increases correspondingly, requiring smaller transistor sizes which shortens the channel length and deteriorates driving stability
Solution Approach 1:
The patent introduces a dual-gate structure by adding a second gate electrode on the opposite side of the active layer from the first gate electrode. This dimensional change from single-gate to dual-gate configuration allows independent control of channel conductivity, enabling effective channel length to be maintained even as transistor size is reduced for high-resolution displays.
Solution Approach 2:
The patent changes the electrical parameters by applying different voltages to the first and second gate electrodes. By independently controlling the voltages on both gates, the channel conductivity can be precisely regulated, maintaining driving stability despite reduced channel length in miniaturized transistors for high pixel density displays.
2Productivity
If the size of the thin film transistor is reduced to dispose more transistors in a certain area, then the pixel density is improved, but the channel length is shortened, whereby driving stability is deteriorated
Solution Approach 1:
By adding the second gate electrode on the opposite side of the active layer, the patent creates a dual-gate structure that provides an additional control dimension. This allows the transistor to maintain effective channel length and driving stability even when the overall transistor footprint is reduced to increase pixel density.
Solution Approach 2:
The independent voltage control of both gate electrodes enables precise adjustment of channel conductivity parameters. This parameter control mechanism ensures driving stability is maintained in miniaturized transistors with reduced channel lengths required for high pixel density displays.
3Ease of manufacture
If an oxide semiconductor is used as the active layer to achieve transparency and low manufacturing temperature, then the manufacturing cost is reduced and transparency is improved, but stability and mobility are deteriorated as compared with polycrystalline silicon
Solution Approach 1:
The dual-gate structure enables independent voltage control of the oxide semiconductor channel, allowing optimization of conductivity parameters. This compensates for the inherently lower mobility of oxide semiconductors by providing enhanced electrical control, achieving stability comparable to polycrystalline silicon while maintaining the manufacturing advantages of oxide materials.
Solution Approach 2:
The second gate electrode serves multiple functions: it controls channel conductivity, compensates for low mobility of oxide semiconductor, and provides additional control for stabilizing device performance. This multi-functional gate structure enables oxide semiconductors to achieve reliability levels previously only attainable with polycrystalline silicon.
4Ease of manufacture
If the conductorized area is permeated into the channel without uniform length control, then the manufacturing process is simplified, but the effective channel length is not maintained uniformly, whereby property deviation occurs between thin film transistors
Solution Approach 1:
By controlling the voltage applied to the second gate electrode, the patent can precisely adjust the effective channel length and conductivity. This electrical parameter control compensates for variations in conductorized area penetration, ensuring uniform effective channel length across all transistors despite manufacturing tolerances, thereby reducing property deviation.
Data Source
AI summary
One embodiment of the present disclosure provides a thin film transistor comprising an auxiliary electrode, a gate electrode and an active layer disposed between the auxiliary electrode and the gate electrode, wherein the active layer includes a channel portion overlapped with the gate electrode, a first connection portion disposed at one side of the channel portion, and a second connection portion disposed at the other side of the channel portion, and the channel portion includes a first portion overlapped with the auxiliary electrode and a second portion not overlapped with the auxiliary electrode. One embodiment of the present disclosure also provides a display apparatus comprising the thin film transistor.