Oxide Transistor Oxygen Gradient for Display Panel Reliability
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Solution Overview
Problem
Existing display panels face challenges in durability and reliability, particularly in maintaining stable threshold voltage under positive bias temperature stress, due to the limitations of silicon transistors and the complexity of manufacturing processes.
Innovation Solution
The implementation of an oxide transistor with a specific layered structure, including a bottom gate, oxide semiconductor pattern with varying oxygen atomic percentages, and a top gate, along with a simplified manufacturing method using sputtering processes to minimize threshold voltage variation and reduce the number of conductive layers and masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon transistor is used in display panels, then the manufacturing process is well-established, but the durability and reliability under positive bias temperature stress deteriorates due to threshold voltage variation
Solution Approach 1:
The patent changes the material parameter from silicon semiconductor to oxide semiconductor, which fundamentally alters the electrical properties and reduces threshold voltage variation under stress. This material substitution enables the transistor to maintain stable electrical characteristics under positive bias temperature stress while remaining compatible with existing manufacturing processes.
Solution Approach 2:
The patent employs a composite structure combining oxide semiconductor layers with insulating layers (silicon oxide and silicon nitride) to create a transistor that leverages the advantages of both materials. The oxide semiconductor provides stability under stress, while the insulating layers provide structural support and electrical isolation, together achieving both reliability and manufacturing precision.
2Manufacturing precision
If a complex manufacturing process is used to improve transistor performance, then the threshold voltage stability improves, but the manufacturing complexity and number of conductive layers increases
Solution Approach 1:
The patent merges multiple functions into the oxide semiconductor layer, which simultaneously serves as the active channel and provides inherent stability against threshold voltage variation. This consolidation reduces the need for additional complex conductive layers and masks, simplifying the overall manufacturing process while maintaining threshold voltage stability.
Solution Approach 2:
By changing the semiconductor material parameter to oxide semiconductor, the patent achieves threshold voltage stability with a simpler structure. The oxide semiconductor's inherent properties eliminate the need for complex multi-layer conductive structures, reducing both device complexity and manufacturing steps while maintaining the desired electrical stability.
3Ease of manufacture
If the oxide semiconductor pattern has uniform oxygen content, then the manufacturing process is simpler, but the channel properties and threshold voltage stability deteriorate
Solution Approach 1:
The patent applies local quality by creating regions with different oxygen concentrations within the oxide semiconductor layer. The first region has lower oxygen content for optimal channel conductivity, while the second region has higher oxygen content for stability. This spatial variation in oxygen distribution optimizes both channel properties and threshold voltage stability simultaneously.
Solution Approach 2:
The patent changes the oxygen concentration parameter across different regions of the oxide semiconductor layer. By controlling oxygen content to vary spatially (lower in the first region, higher in the second region), the patent optimizes electrical properties and stability without requiring complex manufacturing steps, achieving both ease of manufacture and reliability.
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 durability and reliability of display panels by reducing threshold voltage variation under positive bias temperature stress and simplifying the manufacturing process, while maintaining desirable channel properties.
Implementation Method 1
a first sputtering process and a second sputtering process
Data Source
AI summary
A display panel includes a light emitting element and a pixel circuit electrically connected to the light emitting element. The pixel circuit includes a transistor. The transistor includes a first gate, an oxide semiconductor member overlapping the first gate, and a second gate overlaps the oxide semiconductor member. The oxide semiconductor member is disposed between the first gate and the second gate and includes a first semiconductor layer and a second semiconductor layer. The second semiconductor layer is disposed between the first semiconductor layer and the second gate in a thickness direction of the oxide semiconductor member. An atomic percent of oxygen of the first semiconductor layer is lower than an atomic percent of oxygen of the second semiconductor layer.