TFT Substrate Ohmic Contact Resistance Reduction via TCO Interlayer
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Solution Overview
Problem
Current oxide semiconductor TFT substrates have high ohm contact resistance between the oxide semiconductor layer and the source/drain, and between the pixel electrode layer and the source/drain, leading to higher driving voltage, power consumption, and lower response speed in flat panel displays.
Innovation Solution
A manufacturing method involving the sequential deposition and patterning of heavily doped transparent conducting thin film layers and metal layers to form a gate, source/drain, and pixel electrode, with specific thicknesses and materials like ITO or IZO, and an IGZO semiconductor layer, to reduce ohm contact resistance through optimized electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the oxide semiconductor layer directly contacts the source/drain, then the device structure is simple, but the ohm contact resistance is large leading to higher power consumption
Solution Approach 1:
The patent introduces a transparent conducting oxide (TCO) layer as an intermediary between the oxide semiconductor layer and the source/drain electrode. This TCO layer serves as a mediator that reduces the contact resistance at the interface, enabling better electrical connection without adding excessive structural complexity. The TCO layer acts as a bridge that facilitates charge carrier transport from the source/drain to the semiconductor channel.
Solution Approach 2:
The patent employs composite material structure by combining the oxide semiconductor layer with a transparent conducting oxide layer at the contact region. This composite structure leverages the beneficial properties of both materials: the oxide semiconductor provides the active channel function while the TCO material provides low-resistance contact and transparency. The composite approach optimizes both electrical performance and optical properties.
2Device complexity
If the oxide semiconductor layer directly contacts the pixel electrode layer, then the device structure is simple, but the ohm contact resistance is large leading to higher driving voltage
Solution Approach 1:
The patent introduces a transparent conducting oxide (TCO) layer as an intermediary between the oxide semiconductor layer and the pixel electrode layer. This TCO layer serves as a mediator that reduces the contact resistance at the interface, enabling better electrical connection without adding excessive structural complexity. The TCO layer acts as a bridge that facilitates charge carrier transport from the semiconductor channel to the pixel electrode.
Solution Approach 2:
The patent employs composite material structure by combining the oxide semiconductor layer with a transparent conducting oxide layer at the contact region. This composite structure leverages the beneficial properties of both materials: the oxide semiconductor provides the active channel function while the TCO material provides low-resistance contact and transparency. The composite approach optimizes both electrical performance and optical properties.
3Device complexity
If the ohm contact resistance is large, then the device structure is simple, but the response speed is low
Solution Approach 1:
The patent introduces a transparent conducting oxide (TCO) layer as an intermediary between the oxide semiconductor layer and the source/drain electrode. This TCO layer serves as a mediator that reduces the contact resistance at the interface, enabling better electrical connection without adding excessive structural complexity. The TCO layer acts as a bridge that facilitates charge carrier transport from the source/drain to the semiconductor channel.
Solution Approach 2:
The patent changes the electrical parameters at the contact interface by introducing the TCO layer with optimized thickness and doping characteristics. By adjusting the thickness of the TCO layer and its doping level, the contact resistance is reduced, which directly improves the response speed of the TFT device. This parameter optimization enables faster charging and discharging of the pixel capacitor.
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 method effectively reduces ohm contact resistance, lowering the threshold voltage and power consumption while increasing the response speed of flat panel displays by enhancing the conductivity between the oxide semiconductor layer, source/drain, and pixel electrode layer.
Implementation Method 1
sequentially deposing and patterning a first heavily doped transparent conducting thin film layer and a first metal layer on the substrate to form a gate and the first heavily doped transparent conducting thin film layer located at a lower surface of the gate
Implementation Method 2
sequentially deposing and patterning a first heavily doped transparent conducting thin film layer and a first metal layer on the substrate
Data Source
AI summary
An oxide semiconductor TFT substrate includes a substrate, a gate and a first heavily doped transparent conducting layer formed on a substrate and covered by a gate isolation layer. An island shaped oxide semiconductor layer and an island shaped etching stopper layer are sequentially formed on the gate isolation layer with two side parts of the oxide semiconductor layer exposed outside the etching stopper layer. A source and a drain are formed on the two side parts of the oxide semiconductor layer to be in electrical connection therewith with a heavily doped transparent conducting layer therebetween. A protecting layer is formed on the source and the drain and is formed with a via. A pixel electrode extends through the via to electrically connect to the source and the drain with a heavily doped transparent conducting layer interposed therebetween and in direct contact therewith.