Oxide Semiconductor Transistor Oxygen Defect Reduction
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Solution Overview
Problem
The reliability of semiconductor devices incorporating transistors with oxide semiconductors is hindered by variations and decreases in electrical characteristics, primarily due to oxygen defects which affect the conductivity and stability under irradiation.
Innovation Solution
A semiconductor device with a bottom-gate transistor structure utilizing an oxide semiconductor film with a spin density of 1×10^18 spins/cm^3 or lower, combined with an oxide insulating film containing nitrogen, such as silicon oxynitride, to reduce oxygen defects and enhance electrical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oxide semiconductor film is used in a transistor, then the device can be manufactured with existing processes, but oxygen defects cause variation and decrease in electrical characteristics
Solution Approach 1:
An oxide insulating film containing nitrogen is introduced as an intermediary layer between the oxide semiconductor film and the environment. This mediator film supplies oxygen to the semiconductor film and prevents oxygen outdiffusion, thereby reducing oxygen defects and stabilizing electrical characteristics while maintaining compatibility with existing manufacturing processes
Solution Approach 2:
The invention changes the chemical composition parameters of the insulating film by incorporating nitrogen into the oxide insulating film. This parameter change enables the film to contain more oxygen than stoichiometric composition, transforming it into an oxygen-rich material that can compensate for oxygen defects in the semiconductor film
2Reliability
If the oxide semiconductor film has high conductivity, then device performance is improved, but oxygen defects increase causing instability under irradiation
Solution Approach 1:
The oxide insulating film containing nitrogen is positioned to preemptively counteract oxygen outdiffusion from the semiconductor film. By containing nitrogen and excess oxygen, the film creates a protective environment that prevents oxygen loss before it can occur during device operation and irradiation, thereby maintaining compositional stability
Solution Approach 2:
The invention uses a composite structure combining oxide semiconductor material with nitrogen-containing oxide insulating material. This composite approach leverages the complementary properties of both materials: the semiconductor provides electrical functionality while the nitrogen-containing oxide provides oxygen reservoir and stability under irradiation
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 approach results in a highly reliable semiconductor device with stable electrical conductivity and reduced variation in characteristics under visible light and ultraviolet irradiation, ensuring improved performance and longevity.
Implementation Method 1
By containing an adequate amount of nitrogen, the oxygen insulating film can contain oxygen more than that in the stoichiometric composition
Implementation Method 2
The number of lone electrons in the oxide semiconductor film can be measured as a spin density of the oxide semiconductor film by electron spin resonance (ESR)
Data Source
AI summary
A highly reliable semiconductor device that includes a transistor including an oxide semiconductor is provided. In a semiconductor device which includes a bottom-gate transistor including an oxide semiconductor film, the spin density of the oxide semiconductor film is lower than or equal to 1×1018 spins/cm3, preferably lower than or equal to 1×1017 spins/cm3, further preferably lower than or equal to 1×1016 spins/cm3. The conductivity of the oxide semiconductor film is lower than or equal to 1×103 S/cm, preferably lower than or equal to 1×102 S/cm, further preferably lower than or equal to 1×101 S/cm.