TFT Second Gate Electrode Stabilization for Display Uniformity
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Solution Overview
Problem
In high-definition displays, the reduced area per pixel makes it difficult to dispose thin film transistors and wiring, and the metal layer's potential stability is affected by variations in the underlying layer, necessitating connection to a predetermined potential without available space for a contact region.
Innovation Solution
A second gate electrode is connected to a predetermined potential above or below a thin film transistor, with the source electrode penetrating through the semiconductor layer to establish electrical connection, eliminating the need for a connection region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal layer is disposed below the thin film transistor to prevent semiconductor layer irradiation, then display uniformity is improved, but the metal layer's potential becomes unstable due to variation in underlying layer potential
Solution Approach 1:
A second gate electrode is introduced as an intermediary between the metal layer and the underlying layer. This second gate electrode is connected to a predetermined potential (ground or power supply potential) through a connection electrode, thereby stabilizing the potential of the metal layer without requiring the metal layer to directly contact the underlying layer. The intermediary structure resolves the contradiction by providing potential stability while maintaining the metal layer's function in preventing semiconductor layer irradiation.
2Reliability
If the metal layer is connected to a predetermined potential to stabilize its potential, then potential stability is improved, but no room is available for forming a contact portion in the display area
Solution Approach 1:
The connection structure is moved from the planar display area to the vertical dimension. The connection electrode extends in the thickness direction of the substrate to connect the second gate electrode to the predetermined potential. This vertical connection approach allows potential stabilization without occupying additional area in the display plane, thereby resolving the contradiction between potential stability and display area availability.
3Manufacturing precision
If the area per pixel is reduced to achieve high definition display, then display resolution is improved, but it becomes difficult to dispose thin film transistors and wiring
Solution Approach 1:
The gate structure is segmented into a first gate electrode and a second gate electrode that are positioned on opposite sides of the semiconductor layer. This segmentation allows the thin film transistor to be configured more compactly, with the semiconductor layer sandwiched between the two gate electrodes. The segmented gate structure reduces the horizontal space required for the transistor, enabling high-definition display with smaller pixel areas while maintaining proper transistor functionality.
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 configuration stabilizes the metal layer's potential and improves display uniformity by ensuring both the source and second gate electrodes are at the same potential, addressing the challenge of limited space in the display area.
Implementation Method 1
The source electrode penetrates through the semiconductor layer and is connected to the second gate electrode on the second side. Both the source electrode and the second gate electrode are at the same potential.
Data Source
AI summary
A display device includes a pixel layer for displaying an image and a circuit layer including a thin film transistor for driving the pixel layer. The thin film transistor includes a semiconductor layer including a channel region and a source region and a drain region sandwiching the channel region, a first gate electrode facing the channel region on a first side which is either above or below the semiconductor layer, a second gate electrode facing at least the channel region and the source region on a second side opposite to the first side, a source electrode connected to the source region, and a drain electrode connected to the drain region. The source electrode penetrates through the semiconductor layer and is connected to the second gate electrode on the second side.