C-Axis-Aligned Oxide Semiconductor Film for Defect-Stable Conductivity
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Solution Overview
Problem
Oxide semiconductor films used in transistors often exhibit unstable electric characteristics due to oxygen vacancies and dangling bonds, leading to reduced reliability in semiconductor devices.
Innovation Solution
An oxide semiconductor film with a c-axis-aligned crystalline region, composed of indium, gallium, and zinc, is developed, which reduces oxygen vacancies, dangling bonds, and impurities, thereby stabilizing the electric characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oxide semiconductor film is kept amorphous, then it is easy to manufacture and can be formed over larger substrates, but oxygen vacancies and dangling bonds are generated leading to unstable electric characteristics
Solution Approach 1:
The patent applies phase transition by transforming the oxide semiconductor film from an amorphous phase to a crystalline phase through controlled heating treatment. This phase transition eliminates oxygen vacancies and dangling bonds that exist in the amorphous state, thereby stabilizing electric characteristics while maintaining manufacturing feasibility through a simple heat treatment process.
Solution Approach 2:
The patent changes the structural parameter of the oxide semiconductor film from amorphous to crystalline by controlling the heating temperature and atmosphere. This parameter change (structural ordering) reduces defect concentration and stabilizes electrical properties, resolving the contradiction between ease of manufacture and reliability.
2Reliability
If an oxide semiconductor film is crystallized, then oxygen vacancies and dangling bonds are reduced improving electric characteristics stability, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes phase transition from amorphous to crystalline state through a controlled heating process. This approach achieves reliable crystalline structure with reduced defects while keeping the manufacturing process relatively simple by using a single heat treatment step rather than complex multi-step crystallization procedures.
Solution Approach 2:
The patent performs preliminary action by forming the oxide semiconductor film with a specific composition (In-Ga-Zn-O) that is predisposed to form a stable crystalline structure during subsequent heating. This preliminary compositional design facilitates easy crystallization and reduces the complexity of the overall manufacturing process.
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 c-axis-aligned crystalline structure ensures stable electric conductivity and reliability of semiconductor devices, even under exposure to visible light and ultraviolet radiation.
Implementation Method 1
an oxide semiconductor film which contains indium, gallium, and zinc and includes a c-axis-aligned crystalline region
Data Source
AI summary
To provide an oxide semiconductor film having stable electric conductivity and a highly reliable semiconductor device having stable electric characteristics by using the oxide semiconductor film. The oxide semiconductor film contains indium (In), gallium (Ga), and zinc (Zn) and includes a c-axis-aligned crystalline region aligned in the direction parallel to a normal vector of a surface where the oxide semiconductor film is formed. Further, the composition of the c-axis-aligned crystalline region is represented by In1+δGa1−δO3(ZnO)m (0<δ<1 and m=1 to 3 are satisfied), and the composition of the entire oxide semiconductor film including the c-axis-aligned crystalline region is represented by InxGayO3(ZnO)m (0<x<2, 0<y<2, and m=1 to 3 are satisfied).