Oxide Semiconductor Film Oxygen Release Prevention
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Solution Overview
Problem
Oxide semiconductor transistors with c-axis aligned crystal parts face issues with oxygen vacancies, leading to unstable electrical characteristics and reduced reliability due to oxygen release from side surfaces, which affects the transistor's performance under bias-temperature stress and light irradiation.
Innovation Solution
A semiconductor device structure is implemented with a first and second oxide semiconductor film, both containing indium, gallium, and zinc, where the second film has a higher indium content and the oxide film has a higher gallium content, stacked over the first film, with the oxide film covering the side surfaces to prevent oxygen release and maintain sufficient oxygen, thereby enhancing the crystallinity and reliability of the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an amorphous oxide semiconductor film is used, then the transistor can be manufactured more easily compared to polycrystalline silicon, but the electrical characteristics become unstable due to oxygen vacancies
Solution Approach 1:
The patent changes the structural parameters of the oxide semiconductor film by forming c-axis aligned crystal parts within the film. This structural transformation from amorphous to partially crystalline state reduces oxygen vacancies while maintaining the ease of manufacturing associated with oxide semiconductors, thereby resolving the contradiction between ease of manufacture and electrical characteristics stability.
Solution Approach 2:
The patent creates a composite structure within the oxide semiconductor film by forming c-axis aligned crystal parts (CAAC-OS) within the amorphous matrix. This composite approach combines the manufacturing advantages of amorphous films with the stability benefits of crystalline structures, achieving both ease of manufacture and reliable electrical characteristics.
2Device complexity
If the oxide semiconductor film is amorphous, then manufacturing is simpler, but oxygen vacancies are generated easily leading to threshold voltage shifts
Solution Approach 1:
The patent modifies the structural parameters of the oxide semiconductor film by introducing c-axis aligned crystal parts. This changes the atomic arrangement from completely random (amorphous) to partially ordered (c-axis aligned), which reduces oxygen vacancy formation and stabilizes threshold voltage while maintaining relatively simple manufacturing processes.
3Reliability
If c-axis aligned crystal parts are formed in the oxide semiconductor film, then oxygen vacancy generation is suppressed and electrical characteristics stabilize, but the film structure becomes more complex
Solution Approach 1:
The patent applies local quality by forming c-axis aligned crystal parts only in specific regions or orientations within the oxide semiconductor film, rather than requiring complete crystallization. This localized crystalline ordering provides the necessary stability against oxygen vacancies while maintaining overall structural simplicity and ease of manufacture.
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 structure effectively suppresses oxygen vacancy generation and improves the crystallinity of the oxide semiconductor film, leading to more stable electrical characteristics and increased reliability of the semiconductor device by maintaining sufficient oxygen and reducing parasitic channel formation.
Implementation Method 1
the oxide film covering the side surfaces to prevent oxygen release and maintain sufficient oxygen
Data Source
AI summary
A semiconductor device in which release of oxygen from side surfaces of an oxide semiconductor film including c-axis aligned crystal parts can be prevented is provided. The semiconductor device includes a first oxide semiconductor film, a second oxide semiconductor film including c-axis aligned crystal parts, and an oxide film including c-axis aligned crystal parts. In the semiconductor device, the first oxide semiconductor film, the second oxide semiconductor film, and the oxide film are each formed using a IGZO film, where the second oxide semiconductor film has a higher indium content than the first oxide semiconductor film, the first oxide semiconductor film has a higher indium content than the oxide film, the oxide film has a higher gallium content than the first oxide semiconductor film, and the first oxide semiconductor film has a higher gallium content than the second oxide semiconductor film.