Display Transistors with Local Oxide Layers and Hydrogen Tuning
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Solution Overview
Problem
Manufacturing transistors with different characteristics for display devices is challenging due to productivity and cost constraints, particularly in achieving a wide driving voltage range for driving transistors and high mobility for switching transistors.
Innovation Solution
Incorporating an oxide layer only in the driving transistor and optimizing the hydrogen concentration in the gate insulating layers of both transistors to enhance the driving voltage range and mobility, respectively, using a substrate with specific active layers and gate electrodes made of materials like indium, gallium, zinc, and oxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transistors with different characteristics are manufactured for driving and switching functions, then the driving voltage range of driving transistor is improved and mobility of switching transistor is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies local quality by selectively forming an oxide layer only in the driving transistor region and not in the switching transistor region. This creates different local structures with different functions: the oxide layer in the driving transistor provides a wide driving voltage range, while the absence of oxide layer in the switching transistor maintains high mobility. The gate insulating layers also have different hydrogen concentrations in different regions to optimize respective transistor characteristics.
Solution Approach 2:
The patent segments the gate insulating layer structure into two distinct types: a first gate insulating layer with lower hydrogen concentration for the driving transistor, and a second gate insulating layer with higher hydrogen concentration for the switching transistor. This segmentation allows each transistor type to have optimized characteristics while using a unified manufacturing process flow.
2Reliability
If transistors with different characteristics are manufactured for driving and switching functions, then the driving voltage range of driving transistor is improved and mobility of switching transistor is improved, but the manufacturing time and productivity decrease
Solution Approach 1:
The patent achieves universality by using a unified manufacturing process that forms both driving and switching transistors with different characteristics simultaneously. The oxide layer formation process is applied selectively to driving transistor regions, and the gate insulating layer deposition is performed across the entire substrate, creating different transistor types through a single integrated process flow rather than separate manufacturing steps.
Solution Approach 2:
The patent applies local quality by selectively forming an oxide layer only in the driving transistor region and not in the switching transistor region. This creates different local structures with different functions: the oxide layer in the driving transistor provides a wide driving voltage range, while the absence of oxide layer in the switching transistor maintains high mobility. The gate insulating layers also have different hydrogen concentrations in different regions to optimize respective transistor characteristics.
3Ease of manufacture
If uniform gate insulating layers are used for both transistors, then the manufacturing process is simplified, but the driving voltage range of driving transistor and mobility of switching transistor cannot be optimized
Solution Approach 1:
The patent applies local quality by selectively forming an oxide layer only in the driving transistor region and not in the switching transistor region. This creates different local structures with different functions: the oxide layer in the driving transistor provides a wide driving voltage range, while the absence of oxide layer in the switching transistor maintains high mobility. The gate insulating layers also have different hydrogen concentrations in different regions to optimize respective transistor characteristics.
Solution Approach 2:
The patent changes the hydrogen concentration parameter of the gate insulating layers in different regions. The first gate insulating layer has a lower hydrogen concentration to achieve a wide driving voltage range in the driving transistor, while the second gate insulating layer has a higher hydrogen concentration to achieve high mobility in the switching transistor. This parameter variation is achieved through selective deposition or treatment processes.
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 effectively increases the driving voltage range of the driving transistor and electron mobility of the switching transistor, improving the overall performance and efficiency of the display device.
Implementation Method 1
an oxide layer disposed on the first gate insulating layer and including an oxide semiconductor
Implementation Method 2
a hydrogen concentration of a first gate insulating layer between a first active layer and a first gate electrode of the first transistor is made lower than a hydrogen concentration of a second gate insulating layer between a second active layer and a second gate electrode of the second transistor, thereby increasing the driving voltage range of the first transistor
Data Source
AI summary
A display device is provided. The display device includes a substrate, a first active layer of a first transistor and a second active layer of a second transistor which are disposed on the substrate, a first gate insulating layer disposed on the first active layer, an oxide layer disposed on the first gate insulating layer and including an oxide semiconductor, a first gate electrode disposed on the oxide layer, a second gate insulating layer disposed on the first gate electrode and the second active layer, and a second gate electrode which overlaps the second active layer in a thickness direction of the substrate and is disposed on the second gate insulating layer, where the oxide layer overlaps the first active layer and does not overlap the second active layer in the thickness direction.