Barrier Layer for Hydrogen Diffusion in Display Substrates
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Solution Overview
Problem
The integration of low-temperature polysilicon thin-film transistors in display technology leads to hydrogen diffusion into metal oxide thin-film transistors during high-temperature processes, reducing the reliability of the driving backplane and potentially causing failure.
Innovation Solution
A method is introduced where a barrier layer is prepared over the active layer of the metal oxide transistor to prevent hydrogen diffusion, followed by the formation of low-temperature polysilicon transistors, ensuring the active layer's integrity during subsequent high-temperature processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-temperature polysilicon thin-film transistors are prepared using high-temperature processes, then the transistor mobility and charging speed are improved, but hydrogen diffuses into the metal oxide thin-film transistor active layer, reducing reliability
Solution Approach 1:
A barrier layer is introduced as an intermediary between the metal oxide thin-film transistor active layer and the low-temperature polysilicon thin-film transistor. This barrier layer prevents hydrogen diffusion from the polysilicon transistor preparation process into the metal oxide transistor active layer, while allowing the high-temperature processes to proceed for achieving high mobility and charging speed in the polysilicon transistor.
Solution Approach 2:
The barrier layer is prepared in advance, before the low-temperature polysilicon thin-film transistor preparation process. This preliminary action ensures that the metal oxide thin-film transistor active layer is protected from hydrogen diffusion before the high-temperature processes begin, maintaining reliability while enabling subsequent high-speed transistor fabrication.
2Reliability
If a barrier layer is added to prevent hydrogen diffusion, then the reliability of the metal oxide thin-film transistor is improved, but the device structure and fabrication process become more complex
Solution Approach 1:
The barrier layer serves multiple functions: it acts as a hydrogen diffusion barrier to protect the metal oxide thin-film transistor active layer, and simultaneously serves as the gate insulating layer for the low-temperature polysilicon thin-film transistor. This multi-functionality reduces the total number of layers needed, simplifying the overall device structure despite the added protection function.
Solution Approach 2:
The barrier layer and the gate insulating layer are merged into a single layer. Instead of having separate barrier and gate insulating layers, the patent combines these functions into one layer, reducing structural complexity while maintaining both the protection function and the gate insulation function.
3Reliability
If multiple separate layers are used for barrier and gate insulating functions, then the protection function is ensured, but the fabrication process steps increase
Solution Approach 1:
The barrier layer is designed to perform dual functions: preventing hydrogen diffusion and serving as the gate insulating layer. This eliminates the need for separate fabrication steps for creating the gate insulating layer, as it is formed simultaneously with the barrier layer, thereby improving fabrication process efficiency while maintaining protection function.
Solution Approach 2:
The fabrication process merges the formation of the barrier layer and gate insulating layer into a single step. By combining these two functions into one layer formed in one process step, the total number of fabrication steps is reduced, improving productivity without compromising the hydrogen diffusion protection.
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 approach enhances the reliability of the display substrate by preventing hydrogen-induced degradation, simplifying the fabrication process, and maintaining high display quality and resolution.
Implementation Method 1
preparing a barrier layer on a surface of the first active layer away from the substrate... When these high-temperature processes are carried out, it is easy to diffuse hydrogen into the active layer of the metal oxide thin film transistor. These lead to a reduction in the reliability of the driving backplane
Data Source
AI summary
The present disclosure provides a display substrate, a method for preparing the same, and a display device. The method for preparing the display substrate includes a step of preparing a pixel driving circuit on a substrate, the step specifically includes: preparing a first active layer of an oxide transistor on the substrate; preparing a barrier layer on a surface of the first active layer away from the substrate, an orthogonal projection of the barrier layer on the substrate covering an orthogonal projection of the first active layer on the substrate; preparing a low-temperature polysilicon transistor is on the substrate; and preparing a first gate insulating layer, a first gate electrode, a first input electrode, and a first output electrode of the oxide transistor on the substrate.