Oxide TFT Display Stack for Fewer Masks and Hydrogen Blocking
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Solution Overview
Problem
Existing display device manufacturing processes require multiple masks, leading to increased costs and potential defects like optical leakage and hydrogen intrusion due to direct contact between the active layer and insulating layers, which affects transistor functionality.
Innovation Solution
A manufacturing method that reduces the number of masks by using an oxygen supply layer and a hydrogen diffusion prevention layer, comprising metal oxides like IGZO and Al2O3, to prevent light exposure and hydrogen ingress, while maintaining transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light shielding film is provided under the active layer to prevent optical leakage, then optical leakage is prevented, but the number of masks and manufacturing cost increase
Solution Approach 1:
The patent combines the light shielding function with the existing buffer layer by using the same material (IGZO) for both the semiconductor layer and the buffer layer. This merging eliminates the need for a separate light shielding film and its associated mask process, while still preventing optical leakage and hydrogen intrusion effectively.
Solution Approach 2:
The buffer layer is given multiple functions: it serves as both a structural buffer layer and a light shielding layer. By using IGZO material that has both semiconductor properties and light shielding properties, the same layer performs multiple protective functions, reducing the need for additional components.
2Device complexity
If the active layer and insulating layer directly contact to reduce masks, then manufacturing cost reduces, but hydrogen flows into the active layer and transistor function is lost
Solution Approach 1:
The patent introduces the buffer layer as an intermediary between the active layer and the insulating layer. This buffer layer acts as a barrier that prevents hydrogen from the insulating layer from penetrating into the active layer, while still allowing the structure to maintain a reduced number of masks by eliminating the need for a separate light shielding film.
3Reliability
If multiple masks are used to prevent hydrogen intrusion, then transistor functionality is maintained, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent merges the protective functions into the existing buffer layer structure, eliminating the need for additional mask processes. The IGZO-based buffer layer provides both hydrogen barrier properties and light shielding properties, simplifying the manufacturing process while maintaining transistor functionality.
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 simplifies the manufacturing process, reduces costs, and ensures stable transistor operation by minimizing optical leakage and hydrogen diffusion, thereby enhancing the reliability of the display device.
Implementation Method 1
an oxygen supply layer positioned under the second conductive layer, in contact with the second conductive layer
Implementation Method 2
a metal oxide layer positioned between the insulating layer and the second conductive layer
Data Source
AI summary
A display device according to an embodiment includes: a substrate; a first conductive layer positioned on the substrate; a semiconductor layer positioned on the first conductive layer; a second conductive layer positioned on the semiconductor layer; an oxygen supply layer positioned under the second conductive layer, in contact with the second conductive layer, and having the same planar shape as the second conductive layer; and a light-emitting element connected to the second conductive layer, wherein the oxygen supply layer includes a metal oxide that includes one or more of indium, zinc, tin, or gallium, or alloys thereof.