Display Transistors With Split Metal-Oxide Gates for Low Scan Resistance
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Solution Overview
Problem
Existing transistors using oxide semiconductors face issues with high gate capacitance, increased resistance of scan lines, and difficulty in high-definition pixel arrangement due to complex manufacturing processes.
Innovation Solution
A display device design incorporating transistors with a first gate electrode made of metal and a second gate electrode made of metal oxide, connected to separate wirings, reduces gate capacitance and scan line resistance while allowing high-density pixel arrangement without increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate electrode made of metal oxide that releases oxygen by heating is used as a top gate, then transistor reliability is improved, but the resistance of the gate electrode and scan line increases
Solution Approach 1:
The gate electrode is divided into two separate gate electrodes: a first gate electrode made of metal with low resistance, and a second gate electrode made of metal oxide that releases oxygen. This segmentation allows each gate electrode to fulfill its specific function independently, resolving the contradiction between reliability improvement and resistance increase
Solution Approach 2:
The first gate electrode (metal) and second gate electrode (metal oxide) are combined in a stacked configuration to form a composite gate structure. This merging allows the low-resistance metal gate to compensate for the high resistance of the metal oxide gate, while the metal oxide gate provides oxygen release functionality for improved transistor reliability
2Loss of energy
If a single-gate structure is used, then gate capacitance is reduced, but the electrical surrounding effect that improves field-effect mobility is lost
Solution Approach 1:
The single gate is segmented into two separate gates (first gate electrode and second gate electrode) that can be independently controlled. This segmentation reduces gate capacitance by eliminating the need for a thick metal oxide layer in a single-gate structure, while still providing the electrical surrounding effect through the stacked configuration
Solution Approach 2:
The gate structure transitions from a planar single-gate configuration to a vertical stacked multi-gate configuration. This dimensional change allows the transistor to achieve both reduced gate capacitance and improved field-effect mobility by electrically surrounding the oxide semiconductor layer with multiple gate electrodes in the vertical dimension
3Object-affected harmful factors
If metal wiring is stacked over a gate electrode to reduce scan line resistance, then resistance is reduced, but the number of manufacturing steps increases
Solution Approach 1:
The scan line is merged with the first gate electrode (made of metal) in the same layer, eliminating the need for separate metal wiring stacking. This integration reduces scan line resistance while maintaining manufacturing simplicity by forming both the scan line and first gate electrode simultaneously in a single fabrication step
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 achieves reduced gate capacitance, low scan line resistance, and enables high-definition display without additional manufacturing costs, improving transistor reliability and pixel density.
Implementation Method 1
a gate electrode that is formed with, for example, an oxide layer and releases oxygen by being heated
Implementation Method 2
an oxide layer where a channel is formed is electrically surrounded by electric fields of top and bottom gate electrodes to achieve high field-effect mobility
Data Source
AI summary
A novel display device or the like in which a transistor connected to a scan line has small gate capacitance is provided. A novel display device or the like in which a scan line has low resistance is provided. A novel display device or the like in which pixels can be arranged with high density is provided. A novel display device or the like that can be manufactured without an increase in cost is provided. In a transistor including a first gate electrode and a second gate electrode, the first gate electrode is formed using a metal material with low resistance and the second gate electrode is formed using a metal oxide material that can reduce oxygen vacancies in an oxide semiconductor layer. The first gate electrode is connected to the scan line, and the second gate electrode is connected to a wiring to which a constant potential is supplied.