Source/Drain Electrodes for Thin-Film Transistors Without Barrier Layers
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Solution Overview
Problem
Conventional thin-film transistor substrates for liquid crystal display devices face issues with interdiffusion between aluminum alloy source/drain electrodes and amorphous silicon semiconductor layers, leading to decreased ON-state current, increased OFF-state current, and poor thermal stability, which necessitates the use of barrier metal layers that increase production costs and complexity.
Innovation Solution
The implementation of source/drain electrodes with a nitrogen-containing layer, such as silicon nitride or silicon oxynitride, that binds to silicon, allowing direct connection between the aluminum alloy and the semiconductor layer without the need for barrier metal layers, using an Al-Ni alloy with specific nickel content for improved electrical properties and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier metal layers are used to prevent interdiffusion between aluminum alloy source/drain electrodes and amorphous silicon semiconductor layers, then interdiffusion is reduced, but production cost and device complexity increase
Solution Approach 1:
The invention removes the barrier metal layer from the conventional structure, using only an aluminum alloy layer in direct contact with the amorphous silicon semiconductor layer. This extraction of the barrier metal layer simplifies the device structure while maintaining interdiffusion prevention through controlled alloy composition and deposition conditions.
Solution Approach 2:
The invention changes the compositional parameters of the aluminum alloy layer, specifically controlling the alloying element content to be 0.1-10 atomic percent. This parameter adjustment allows the aluminum alloy layer to function both as a conductive electrode and as a layer that prevents excessive interdiffusion with the semiconductor, eliminating the need for separate barrier layers.
2Reliability
If barrier metal layers are used to prevent interdiffusion, then semiconductor layer properties are maintained, but manufacturing cost increases
Solution Approach 1:
The invention extracts and eliminates the barrier metal layer from the multi-layer structure, reducing the number of deposition steps and materials required. This simplification directly reduces manufacturing cost while maintaining semiconductor layer performance through optimized aluminum alloy composition.
Solution Approach 2:
The aluminum alloy layer is designed to perform multiple functions simultaneously: providing electrical conductivity as an electrode and preventing interdiffusion as a barrier. This multi-functionality is achieved by selecting specific alloying elements and concentrations, eliminating the need for separate barrier metal layers and reducing overall manufacturing cost.
3Device complexity
If conventional aluminum alloy source/drain electrodes are used without barrier metal layers, then device complexity is reduced, but interdiffusion occurs leading to poor thermal stability
Solution Approach 1:
The invention modifies the compositional parameters of the aluminum alloy layer by controlling the alloying element content to be 0.1-10 atomic percent. This parameter control creates an optimal balance between maintaining structural simplicity and achieving sufficient thermal stability to prevent harmful interdiffusion during device operation and manufacturing processes.
Solution Approach 2:
The invention uses a composite aluminum alloy material consisting of aluminum combined with specific alloying elements at controlled concentrations. This composite structure provides both the electrical conductivity needed for electrode function and the thermal stability required to prevent interdiffusion, all within a single layer without requiring additional barrier metals.
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 achieves excellent thin-film transistor properties, high thermal stability, and low contact resistivity without the need for barrier metal layers, simplifying the manufacturing process and reducing production costs while maintaining or exceeding the performance of conventional equivalents.
Implementation Method 1
nitrogen of the nitrogen-containing layer binds to silicon of the thin-film transistor semiconductor layer
Implementation Method 2
the amorphous silicon semiconductor layer and a thin film of pure aluminum or an aluminum alloy are directly connected to each other
Data Source
AI summary
A source/drain electrode is used in a thin-film transistor substrate containing a substrate, a thin-film transistor semiconductor layer, source/drain electrodes, and a transparent picture electrode. The source/drain electrode includes a nitrogen-containing layer and a thin film of pure aluminum or an aluminum alloy. Nitrogen of the nitrogen-containing layer binds to silicon of the thin-film transistor semiconductor layer, and the thin film of pure aluminum or aluminum alloy is connected to the thin-film transistor semiconductor layer through the nitrogen-containing layer.