Crystalline Oxide Semiconductor Film Nucleation and Impurity Control
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Solution Overview
Problem
The electrical characteristics of oxide semiconductor-based transistors are unstable due to the sensitivity of oxide semiconductors to hydrogen and water, and changes in conductivity occur during manufacturing, affecting the reliability and stability of semiconductor devices.
Innovation Solution
A method for manufacturing a semiconductor device involving the formation of a stack of material films with a hexagonal crystal structure, using a first material film with a wurtzite or corundum crystal structure as a nucleus for a crystalline oxide semiconductor film, and optimizing sputtering conditions to minimize impurity entry, including setting substrate temperature between 200°C and 400°C and maintaining low pressure and leakage rates to form a crystalline oxide semiconductor with reduced impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide semiconductor is used for transistor channel formation, then the device can be manufactured with simpler materials and processes, but the electrical characteristics become unstable due to sensitivity to hydrogen and water impurities
Solution Approach 1:
The patent employs an inert atmosphere environment during the sputtering process to prevent hydrogen and water impurities from entering the oxide semiconductor film. By maintaining a controlled inert atmosphere in the sputtering chamber, the method eliminates the sensitivity issue to impurities while preserving the manufacturing simplicity of using oxide semiconductors.
Solution Approach 2:
The patent changes the sputtering parameters including substrate temperature (200°C to 400°C), pressure conditions, and leakage rate control to optimize the film formation process. These parameter adjustments ensure low impurity concentration in the oxide semiconductor while maintaining ease of manufacture through controlled deposition conditions.
2Device complexity
If conventional sputtering conditions are used, then the manufacturing process is simple, but impurities such as hydrogen and water enter the oxide semiconductor causing conductivity changes
Solution Approach 1:
The patent implements an inert atmosphere environment in the sputtering chamber to prevent harmful impurities like hydrogen and water from entering the oxide semiconductor film during deposition, thereby reducing impurity concentration without significantly increasing process complexity.
Solution Approach 2:
The patent optimizes sputtering parameters including substrate temperature (200°C to 400°C), pressure, and leakage rate to minimize impurity entry while maintaining a relatively simple manufacturing process. These controlled parameter changes ensure high film quality without excessive process complexity.
3Productivity
If large-sized substrates are used for mass production, then productivity increases, but maintaining uniform crystal structure and low impurity concentration becomes more difficult
Solution Approach 1:
The patent maintains specific sputtering parameters including substrate temperature (200°C to 400°C), pressure, and leakage rate across large-sized substrates to ensure uniform crystal structure formation and consistent low impurity concentration throughout the film, enabling mass production with high precision.
Solution Approach 2:
The patent uses a first material film with hexagonal crystal structure as a nucleus layer before forming the oxide semiconductor film. This preliminary action prepares the substrate surface with a uniform crystal template that guides the formation of uniform oxide semiconductor crystals across large substrate areas, ensuring manufacturing precision in mass production.
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 semiconductor devices with stable electrical characteristics and high reliability, enabling mass production of reliable transistors using large-sized substrates by reducing impurity concentrations and maintaining crystal structure integrity.
Implementation Method 1
forming a second material film having a hexagonal crystal structure (a crystalline oxide semiconductor film) using the first material film as a nucleus
Implementation Method 2
forming a stack of the first material film and the second material film where the second material film is formed using the first material film as a nucleus
Implementation Method 3
optimizing sputtering conditions to minimize impurity entry, including setting substrate temperature between 200°C and 400°C and maintaining low pressure and leakage rates
Data Source
AI summary
An object is to provide a semiconductor device including an oxide semiconductor film, which has stable electrical characteristics and high reliability. A stack of first and second material films is formed by forming the first material film (a film having a hexagonal crystal structure) having a thickness of 1 nm to 10 nm over an insulating surface and forming the second material film having a hexagonal crystal structure (a crystalline oxide semiconductor film) using the first material film as a nucleus. As the first material film, a material film having a wurtzite crystal structure (e.g., gallium nitride or aluminum nitride) or a material film having a corundum crystal structure (α-Al2O3, α-Ga2O3, In2O3, Ti2O3, V2O3, Cr2O3, or α-Fe2O3) is used.