Crystalline Oxide Semiconductor Film Manufacturing via Zinc Seed
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Solution Overview
Problem
Semiconductor devices using oxide semiconductors face instability in electric characteristics due to hydrogen or moisture exposure and light irradiation, leading to variations in conductivity and reliability issues, especially when manufactured on large substrates.
Innovation Solution
A method to form a crystalline oxide semiconductor film with a hexagonal crystal structure by preferentially depositing zinc and then tin or indium using a sputtering process, creating a seed crystal for crystal growth, which results in a single crystal or substantially single crystal film with improved orderliness and reduced impurities, enhancing stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If amorphous silicon is used to form transistors over glass substrates, then large glass substrates can be manufactured, but field effect mobility is low
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which fundamentally alters the electrical properties while maintaining compatibility with large glass substrates. This material substitution enables high field effect mobility without sacrificing the ability to manufacture on large-area substrates.
Solution Approach 2:
The invention uses composite material structures including oxide semiconductor films combined with specific insulating layers and electrode configurations. This composite approach optimizes both the electrical performance (mobility) and the manufacturability on large glass substrates.
2Reliability
If polycrystalline silicon is used to form transistors, then field effect mobility is high, but it is not suitable for larger glass substrates
Solution Approach 1:
The patent changes the material phase and composition from polycrystalline silicon to oxide semiconductor, maintaining the high mobility characteristic while enabling deposition on large-area glass substrates that would be unsuitable for polycrystalline silicon processing.
3Ease of manufacture
If oxide semiconductor is used in transistor manufacturing, then manufacturing simplicity is improved, but electric characteristics become unstable due to hydrogen or moisture exposure and light irradiation
Solution Approach 1:
The patent extracts and removes harmful impurities such as hydrogen and moisture from the oxide semiconductor film through careful process design and in-situ treatments. This extraction eliminates the sources of instability while maintaining the manufacturing simplicity of oxide semiconductor processing.
Solution Approach 2:
The invention employs inert atmosphere processing and protective layer structures to prevent exposure to hydrogen and moisture during manufacturing and operation. This creates a stable environment that preserves electric characteristics while keeping the manufacturing process simple.
Solution Approach 3:
The patent performs preliminary treatments such as in-situ heating and protective layer formation before the oxide semiconductor film is exposed to potentially harmful environments. This preliminary action prevents impurity incorporation and stabilizes the film properties in advance.
4Ease of manufacture
If conventional oxide semiconductor films are manufactured, then manufacturing simplicity is maintained, but negative-bias temperature stress photo-degradation occurs
Solution Approach 1:
The patent converts the typically harmful effect of light irradiation into a beneficial characterization tool. By carefully controlling and measuring photo-response characteristics, the invention identifies optimal processing conditions that actually improve stability under light exposure, turning the degradation mechanism into a quality assurance method.
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 crystalline oxide semiconductor film exhibits stable electric characteristics and high reliability, with reduced negative-bias temperature stress photo-degradation and improved photo-response characteristics, enabling mass production of reliable semiconductor devices on large substrates.
Implementation Method 1
a sputtering method is used to form a crystalline oxide semiconductor film
Implementation Method 2
crystal growth is caused using the seed crystal as a nucleus, so that a single crystal oxide semiconductor film or a substantially single crystal oxide semiconductor film can be formed
Data Source
AI summary
An object is to manufacture a semiconductor device including an oxide semiconductor film, which has stable electric characteristics and high reliability. A crystalline oxide semiconductor film is formed, without performing a plurality of steps, as follows: by utilizing a difference in atomic weight of plural kinds of atoms included in an oxide semiconductor target, zinc with low atomic weight is preferentially deposited on an oxide insulating film to form a seed crystal including zinc; and tin, indium, or the like with high atomic weight is deposited on the seed crystal while causing crystal growth. Further, a crystalline oxide semiconductor film is formed by causing crystal growth using a seed crystal with a hexagonal crystal structure including zinc as a nucleus, whereby a single crystal oxide semiconductor film or a substantially single crystal oxide semiconductor film is formed.