Oxide Semiconductor Transistor Oxygen Supply Gate Insulator
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Solution Overview
Problem
Oxide semiconductor devices face variations in electric characteristics due to deviations from stoichiometric composition, oxygen vacancies, and the introduction of impurities like hydrogen or water during manufacturing, leading to instability and reliability issues.
Innovation Solution
The use of a semiconductor device structure where an oxide semiconductor film is dehydrated or dehydrogenated through heat treatment, and a gate insulating film with an oxygen excess region is employed to supply oxygen and prevent impurity reincorporation, utilizing metal oxide films and insulating films with oxygen excess regions to stabilize the oxide semiconductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed to dehydrate or dehydrogenate the oxide semiconductor film, then impurity content is reduced and electrical stability is improved, but manufacturing process complexity increases
Solution Approach 1:
Heat treatment is performed in advance to dehydrate or dehydrogenate the oxide semiconductor film before subsequent manufacturing steps. This preliminary action removes impurities early in the process, preventing their reincorporation later and ensuring electrical stability without requiring complex ongoing controls.
Solution Approach 2:
The heat treatment is conducted in an inert atmosphere to prevent oxidation and impurity contamination during the dehydration and dehydrogenation processes. This creates a controlled environment that maintains film purity while achieving the desired impurity removal.
2Reliability
If a gate insulating film with oxygen excess region is used to supply oxygen to the oxide semiconductor film, then stoichiometric composition is maintained and electrical characteristics are stabilized, but device structure complexity increases
Solution Approach 1:
The gate insulating film is designed with a localized oxygen excess region specifically positioned to contact the oxide semiconductor film. This local concentration of oxygen in the appropriate area supplies oxygen where needed to maintain stoichiometric composition without requiring the entire gate insulating film to have non-stoichiometric composition, thus limiting structural complexity to only the necessary region.
Solution Approach 2:
The gate insulating film is constructed as a composite structure combining regions with different oxygen compositions. This includes an oxygen excess region that supplies oxygen to the oxide semiconductor film and other regions with standard composition, creating a functionally optimized composite structure that balances performance requirements with structural complexity.
3Reliability
If metal oxide films are used as gate insulating film to suppress impurity reincorporation, then reliability is improved, but manufacturing difficulty increases
Solution Approach 1:
Metal oxide films with specific compositional parameters are selected for the gate insulating film to achieve optimal impurity barrier properties. By carefully controlling the metal-to-oxygen ratio and selecting appropriate metal elements, the film exhibits enhanced resistance to impurity reincorporation while remaining compatible with existing manufacturing processes.
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 a transistor with stable electric characteristics and high reliability, reducing temperature-dependent variations and light-induced deterioration, while minimizing impurity effects and maintaining low off-state current.
Implementation Method 1
oxygen is supplied from the gate insulating film to the oxide semiconductor film
Implementation Method 2
an oxide semiconductor film is dehydrated or dehydrogenated by performance of heat treatment
Data Source
AI summary
An object is to provide a semiconductor device including an oxide semiconductor, which has stable electric characteristics and high reliability. In a transistor including an oxide semiconductor film, the oxide semiconductor film is subjected to dehydration or dehydrogenation performed by heat treatment. In addition, as a gate insulating film in contact with the oxide semiconductor film, an insulating film containing oxygen, preferably, a gate insulating film including a region containing oxygen with a higher proportion than the stoichiometric composition is used. Thus, oxygen is supplied from the gate insulating film to the oxide semiconductor film. Further, a metal oxide film is used as part of the gate insulating film, whereby reincorporation of an impurity such as hydrogen or water into the oxide semiconductor is suppressed.