Oxide Semiconductor Transistor with Oxygen Barrier Insulators
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Solution Overview
Problem
Transistors using oxide semiconductors face issues with reliability due to high possibility of change in electric characteristics, particularly exhibiting normally-on characteristics, which complicates the creation of logic circuits and driver circuits, and have challenges with low leakage current in the off state.
Innovation Solution
A semiconductor device structure is developed with multiple insulator layers, including aluminum oxide, that provide a barrier to oxygen and hydrogen, and an excess-oxygen region to enhance the reliability and stability of oxide semiconductor transistors, ensuring low leakage current and maintaining electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide semiconductor transistors are used to achieve high-speed operation and low manufacturing complexity, then manufacturing ease and speed are improved, but reliability deteriorates due to high possibility of change in electric characteristics
Solution Approach 1:
The patent applies local quality by creating an excess-oxygen region in a specific location (the insulator layer adjacent to the oxide semiconductor) to针对性地 address the reliability issue. This localized oxygen enrichment targets the interface where oxygen vacancies most affect transistor characteristics, without requiring changes to the entire device structure, thus maintaining manufacturing simplicity while improving reliability.
Solution Approach 2:
The patent introduces an insulator layer with excess-oxygen region as an intermediary between the oxide semiconductor and other device components. This intermediary layer acts as an oxygen reservoir that supplies oxygen to the oxide semiconductor channel, preventing oxygen vacancies and stabilizing electrical characteristics without requiring direct modification of the oxide semiconductor material itself.
2Speed
If oxide semiconductor transistors are used to achieve high-speed operation, then operation speed is improved, but reliability deteriorates due to normally-on characteristics
Solution Approach 1:
The patent changes the oxygen concentration parameter by creating an excess-oxygen region in the insulator layer. This parameter change directly addresses the normally-on characteristic by ensuring adequate oxygen supply to the oxide semiconductor channel, stabilizing the threshold voltage and enabling proper normally-off operation while maintaining high-speed performance.
3Use of energy by moving object
If oxide semiconductor transistors are used to achieve low power consumption through low leakage current, then power consumption is reduced, but reliability deteriorates due to change in electric characteristics
Solution Approach 1:
The patent applies preliminary action by pre-forming an excess-oxygen region in the insulator layer during the manufacturing process, before the transistor is operated. This preliminary oxygen enrichment prevents oxygen vacancies from forming during subsequent processing and operation, ensuring stable electrical characteristics and reliable low-leakage current performance throughout the device lifetime.
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 solution improves the reliability and stability of oxide semiconductor transistors by reducing oxygen vacancies and hydrogen diffusion, achieving low off-state current and maintaining high on-state current, thus enhancing the overall performance and productivity of semiconductor devices.
Implementation Method 1
The first insulator and the third insulator have a barrier property with respect to oxygen and hydrogen
Implementation Method 2
The second insulator includes an excess-oxygen region
Data Source
AI summary
To provide a highly reliable semiconductor device that is suitable for miniaturization and an increase in density. The semiconductor device includes a first insulator over a substrate, a transistor including an oxide semiconductor over the first insulator, a second insulator over the transistor, and a third insulator over the second insulator. The first insulator and the third insulator have a barrier property with respect to oxygen and hydrogen. The second insulator includes an excess-oxygen region. The transistor is enclosed with the first insulator and the third insulator that are in contact with each other in an edge of a region where the transistor is positioned.