IZTO Oxide Semiconductor Layer for High Mobility Thin Film Transistors
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Solution Overview
Problem
Existing thin film transistors with amorphous oxide semiconductor layers face challenges in achieving high mobility and low defect density, which are crucial for next-generation display devices requiring large size, high resolution, and high-speed driving.
Innovation Solution
The use of an In-Zn-Sn-O (IZTO) oxide semiconductor layer with controlled oxygen partial pressure during deposition, where the oxygen partial pressure is maintained at 15% by volume or less, and the metal element content is optimized within specific atomic percentage ranges, to achieve high mobility and low defect density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If amorphous oxide semiconductor is used for high carrier mobility, then mobility is improved, but defect density increases due to non-uniform composition
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen partial pressure during sputtering deposition (maintaining at 15% by volume or less) and optimizing the metal element composition ratios (In:Zn:Sn in specific ranges). These parameter adjustments enable the formation of IZTO oxide semiconductor layers with both high carrier mobility (15 cm²/Vs or more) and low defect density (7.5×10¹⁵ cm⁻³ or less), resolving the contradiction between mobility improvement and defect reduction.
2Ease of manufacture
If general amorphous silicon is used, then manufacturing is simpler, but carrier mobility is lower compared to oxide semiconductor
Solution Approach 1:
The patent employs composite materials by creating an In-Zn-Sn-O (IZTO) oxide semiconductor system that combines multiple metal elements with oxygen. This composite oxide semiconductor achieves carrier mobility significantly higher than general amorphous silicon while maintaining compatibility with existing TFT manufacturing processes, thus improving speed without sacrificing ease of manufacture.
3Manufacturing precision
If oxygen partial pressure is increased during deposition, then oxide formation is improved, but defect density increases and mobility decreases
Solution Approach 1:
The patent applies parameter changes by establishing a critical threshold for oxygen partial pressure (15% by volume or less) during sputtering deposition. This precise parameter control ensures uniform oxide composition and stoichiometry while preventing excessive oxygen incorporation that would create defects and reduce carrier mobility, thereby achieving both manufacturing precision and high-speed performance.
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 results in a thin film transistor with significantly improved mobility and reduced defect density, leading to a display device with enhanced reliability and performance.
Implementation Method 1
an oxygen partial pressure is not more than 15% by volume when depositing the oxide in the semiconductor layer
Data Source
AI summary
In an oxide for a semiconductor layer of a thin film transistor according to the present invention, wherein metal elements constituting the oxide are In, Zn, and Sn, an oxygen partial pressure is 15% by volume or more when depositing the oxide in the semiconductor layer of the thin film transistor, and a defect density of the oxide satisfies 7.5×1015cm−3 or less, and a mobility satisfies 15 cm2/Vs or more.