Display Device Gate Driver for Hydrogen Diffusion Blocking
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Solution Overview
Problem
Hydrogen diffusion from insulating films affects the active layers of transistors in display devices, leading to reduced effective channel length and unstable threshold voltage in oxide semiconductor transistors, compromising driving reliability.
Innovation Solution
Incorporating first and second type transistors with different active layers (polysilicon and oxide semiconductor) and using electrode patterns to capture and block hydrogen diffusion, with overlapping electrode patterns and light-shielding structures to stabilize potential and prevent hydrogen flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen is not blocked from diffusing through insulating films, then the transistor structure remains simple, but the effective channel length reduces and threshold voltage becomes unstable
Solution Approach 1:
A light-shielding pattern is introduced as an intermediary element between the first and second transistors. This pattern serves dual functions: it blocks hydrogen diffusion from the first transistor to the second transistor, and it provides structural separation. The light-shielding pattern acts as a mediator that prevents harmful hydrogen interaction while maintaining overall device functionality without requiring completely separate transistor structures.
Solution Approach 2:
The light-shielding pattern is designed to perform multiple functions simultaneously: it blocks light, blocks hydrogen diffusion, and provides structural separation between transistors. By making the light-shielding pattern multi-functional, the patent avoids adding separate dedicated hydrogen-blocking structures, thereby improving reliability without proportionally increasing device complexity.
2Reliability
If electrode patterns are added to block hydrogen diffusion, then threshold voltage stability improves, but manufacturing complexity increases
Solution Approach 1:
The electrode pattern is merged with the light-shielding pattern into a single integrated structure. Instead of adding separate electrode patterns and light-shielding patterns as distinct manufacturing steps, the patent combines their functions into one pattern that serves both purposes. This merging reduces the number of separate manufacturing processes while achieving both hydrogen blocking and electrical functionality.
Solution Approach 2:
The combined electrode-light-shielding pattern performs multiple functions: it provides electrical connection, blocks hydrogen diffusion, and shields light. This multi-functionality allows the patent to achieve threshold voltage stability without adding dedicated hydrogen-blocking structures, thereby maintaining ease of manufacture.
3Reliability
If first and second type transistors are used with different active layers, then hydrogen diffusion is blocked, but device complexity increases
Solution Approach 1:
Different active layer materials are used locally in different regions: the first transistor uses a material optimized for its function, while the second transistor uses a different material optimized for hydrogen resistance. This local differentiation allows hydrogen diffusion prevention without requiring all transistors in the device to be complex multi-material structures, thereby limiting the increase in overall device complexity.
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
Prevents hydrogen diffusion, maintains effective channel length, stabilizes threshold voltage, and enhances driving reliability without additional materials or processes, reducing greenhouse gas emissions.
Implementation Method 1
electrode patterns, which are each located in the same layer as that of a gate electrode and a light-shielding pattern of the second type transistor, are sequentially arranged on top of a gate electrode of the first type transistor to capture hydrogen between the first type transistor and the second type transistor
Data Source
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AI summary
A display device includes a substrate comprising an active area and a non-active area, and a power voltage line and a gate driver disposed in the non-active area of the substrate and adjacent to each other. In the display device, the gate driver includes a first type transistor including a first active layer on the substrate, a first gate insulating film on the first active layer, and a first gate electrode overlapping the first active layer and located on the first gate insulating film, a second type transistor including a second active layer farther from the substrate than the first gate electrode, a second gate insulating film on the second active layer, and a second gate electrode overlapping the second active layer and located on the second gate insulating film, and a first electrode pattern overlapping the first gate electrode and located on the second gate insulating film.