Dummy Contact Holes for Hydrogen Diffusion in Oxide Semiconductor Displays
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Solution Overview
Problem
The existing display devices face challenges in simplifying the circuit structure of the driver and reducing power consumption, particularly in preventing hydrogen diffusion into oxide semiconductor layers which can lead to negative threshold voltage shifts and reduced reliability of NMOS transistors.
Innovation Solution
The display device incorporates a pixel circuit part with a first oxide semiconductor layer, a first gate driver with a second oxide semiconductor layer, and a line part with dummy contact holes adjacent to the oxide semiconductor layers. These dummy contact holes allow hydrogen from the inorganic insulating layers to diffuse out, preventing it from reaching the oxide semiconductor layers and thus reducing the negative shift of the threshold voltage and improving transistor reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If inorganic insulating layers are used in the gate driver structure, then device stability and insulation are improved, but hydrogen diffusion into oxide semiconductor layers occurs causing negative threshold voltage shift
Solution Approach 1:
A dummy contact hole is introduced as an intermediary structure to provide a dedicated hydrogen diffusion pathway. This dummy contact hole, filled with conductive material or left empty, serves as a trap for hydrogen atoms migrating from the inorganic insulating layer, preventing them from reaching the oxide semiconductor layer and causing threshold voltage shifts.
Solution Approach 2:
The harmful hydrogen is extracted from the system by providing an alternative escape route through the dummy contact hole. Instead of allowing hydrogen to diffuse into the oxide semiconductor layer, the dummy contact hole acts as a sink that captures and removes hydrogen from the diffusion path, thereby protecting the transistor performance.
2Reliability
If dummy contact holes are added to prevent hydrogen diffusion, then transistor reliability is improved, but device structure complexity increases
Solution Approach 1:
The dummy contact hole is merged with the existing contact hole pattern and inorganic insulating layer structure. It is formed using the same fabrication processes (etching, filling) as the functional contact holes, thereby integrating the hydrogen mitigation function into the existing device architecture without requiring entirely new manufacturing steps.
Solution Approach 2:
The dummy contact hole serves multiple functions: it provides a hydrogen diffusion sink to prevent threshold voltage shifts, maintains the integrity of the inorganic insulating layer by providing a controlled opening, and can be integrated with the clock line structure to provide electrical connection. This multi-functionality reduces the need for additional separate structures.
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 implementation of dummy contact holes in the display device effectively prevents hydrogen diffusion into the oxide semiconductor layers, thereby reducing the negative shift of the threshold voltage and enhancing the reliability of the NMOS transistors, which in turn improves the overall performance and longevity of the display device.
Implementation Method 1
These dummy contact holes allow hydrogen from the inorganic insulating layers to diffuse out, preventing it from reaching the oxide semiconductor layers
Data Source
AI summary
A display device includes a pixel circuit part including a first oxide semiconductor layer, a first gate driver electrically connected to the pixel circuit part, and including a second oxide semiconductor layer at a same layer as the first oxide semiconductor layer, and a first line part electrically connected to the first gate driver, and defining at least one first dummy contact hole adjacent to the second oxide semiconductor layer.