Oxide Thin Film Transistor Sidewall Isolation Against Oxygen Diffusion
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Solution Overview
Problem
The reliability of the active layer in multilayer oxide thin film transistors is poor, affecting the display effect due to oxygen diffusion and oxidation of source-drain metal layers during high temperature processes.
Innovation Solution
A metal oxide active layer is designed with a carrier transport layer and a carrier isolation layer, where the carrier isolation layer covers the lateral surface of the carrier transport layer, reducing oxygen diffusion and oxidation, and a via hole or blind hole is defined in the carrier isolation layer to enhance electrical coupling and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer oxide thin film transistor is designed with multiple high mobility and high impedance layers to improve mobility and stability, then the mobility and stability are improved, but the reliability of the active layer deteriorates due to oxygen diffusion and oxidation during high temperature processes
Solution Approach 1:
A carrier isolation layer is introduced as an intermediary between the carrier transport layer and the environment. This isolation layer specifically targets and blocks oxygen diffusion pathways, preventing oxidation of the source-drain metal layers while maintaining the electrical performance benefits of the multilayer structure.
Solution Approach 2:
The active layer is constructed as a composite structure with at least two different metal oxide materials having different band gaps. The carrier transport layer and carrier isolation layer use different metal oxide materials, creating a composite system where each layer performs its specific function - one layer transports carriers efficiently while the other isolates and protects from oxygen diffusion.
2Object-affected harmful factors
If the carrier isolation layer covers the lateral surface of the carrier transport layer to prevent oxygen diffusion, then oxidation resistance is improved, but device complexity increases due to additional layer configuration
Solution Approach 1:
The active layer is segmented into functionally distinct layers - a carrier transport layer and a carrier isolation layer. Each segment performs a specific function: one transports carriers while the other isolates and protects. This segmentation allows the complex protection function to be achieved through specialized, simplified layers rather than a single complex structure.
Solution Approach 2:
Different regions of the active layer are assigned different properties. The carrier transport layer has high mobility properties optimized for charge transport, while the carrier isolation layer has high impedance properties optimized for oxygen barrier function. Each layer's material composition and structure are locally optimized for its specific function, simplifying the overall design.
3Reliability
If via holes or blind holes are defined in the carrier isolation layer to enhance electrical coupling, then electrical conductivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of requiring precise through-holes through the entire isolation layer, the patent extracts the electrical coupling function to specific locations via via holes or blind holes. These openings are strategically placed only where electrical connection is needed, reducing the overall precision requirements compared to a fully penetrating hole structure while maintaining effective electrical coupling.
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 improves the reliability of the oxide thin film transistor by reducing oxygen diffusion and oxidation, thereby enhancing the stability and performance of the display device.
Implementation Method 1
reducing oxygen diffusion and oxidation
Implementation Method 2
reducing oxygen diffusion and oxidation
Implementation Method 3
enhance electrical coupling and reduce resistance
Data Source
AI summary
An oxide thin film transistor includes: a gate electrode, a metal oxide active layer and a source-drain metal layer, which are on a base substrate. The metal oxide active layer includes a first metal oxide layer and a second metal oxide layer stacked on the first metal oxide layer in a direction away from the base substrate; the first metal oxide layer is a carrier transport layer; the second metal oxide layer is a carrier isolation layer; an electron transfer rate of the carrier transport layer is greater than an electron transfer rate of the carrier isolation layer. The first metal oxide layer includes a primary surface facing toward the base substrate and a primary surface away from the base substrate; the first metal oxide layer further includes a lateral surface around the primary surfaces; the second metal oxide layer covers the lateral surface of the first metal oxide layer.