Oxide Semiconductor Transistor Gate Stack Oxygen Compensation
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Solution Overview
Problem
Semiconductor devices using oxide semiconductors face fluctuations in electric characteristics due to oxygen vacancies, moisture, and hydrogen, leading to instability and reliability issues.
Innovation Solution
The semiconductor device manufacturing process involves sandwiching an oxide semiconductor layer between aluminum oxide films and performing heat treatment to remove impurities and add excess oxygen, reducing oxygen vacancies and stabilizing the electric characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide semiconductor layer is used to form a transistor, then the device can achieve low off-state current and high electron mobility, but the electric characteristics become unstable due to oxygen vacancies, moisture, and hydrogen
Solution Approach 1:
The patent applies preliminary anti-action by performing oxygen supplying treatment and heat treatment before the oxide semiconductor layer is fully formed and before it is exposed to air. The aluminum oxide film is formed first to create a protective barrier, then oxygen is supplied and heat treatment is performed to remove impurities in advance, preventing oxygen vacancies and impurity contamination before they can occur during subsequent processing steps.
Solution Approach 2:
The patent uses an aluminum oxide film as an intermediary protective layer between the oxide semiconductor layer and the external environment. This aluminum oxide film acts as a mediator that prevents moisture and hydrogen from entering the oxide semiconductor layer while allowing oxygen to be supplied to compensate for oxygen vacancies during the heat treatment process.
2Reliability
If heat treatment is performed to remove impurities and add oxygen, then the electric characteristics are stabilized, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges multiple functions into a single heat treatment step. The heat treatment simultaneously performs three functions: (1) removes impurities such as hydrogen and moisture from the oxide semiconductor layer, (2) supplies oxygen to compensate for oxygen vacancies, and (3) stabilizes the electric characteristics. This combination of multiple functions in one step reduces the overall manufacturing process complexity.
Solution Approach 2:
The heat treatment step is designed to be multi-functional, serving as both a dehydration/dehydrogenation process and an oxygen supplying process. By making the heat treatment step universal and multi-functional, the patent avoids the need for separate processing steps for each function, thereby simplifying the manufacturing process while achieving stable electric characteristics.
3Reliability
If aluminum oxide films are formed to suppress oxygen detachment and prevent impurity entry, then the electric characteristics are stabilized, but the manufacturing time and process complexity increase
Solution Approach 1:
The patent performs preliminary action by forming the aluminum oxide film, performing oxygen supplying treatment, and conducting heat treatment all before the oxide semiconductor layer is exposed to air. This preliminary sequence of actions ensures that the protective barrier is in place and oxygen vacancies are compensated before any potential contamination can occur, eliminating the need for additional protective steps later in the manufacturing process.
Solution Approach 2:
The patent maintains continuity of useful action by performing the aluminum oxide film formation, oxygen supplying treatment, and heat treatment in a continuous sequence without exposing the oxide semiconductor layer to air in between steps. This continuous process prevents impurity contamination while achieving oxygen vacancy compensation, thereby stabilizing electric characteristics without requiring additional processing time.
4Ease of manufacture
If the oxide semiconductor layer is exposed to air during manufacturing, then the manufacturing process is simpler, but oxygen vacancies increase and electric characteristics fluctuate
Solution Approach 1:
The patent creates an inert environment by performing all critical processing steps (aluminum oxide film formation, oxygen supplying treatment, heat treatment) without exposing the oxide semiconductor layer to air. This inert environment prevents oxygen vacancies and impurity contamination, ensuring stable electric characteristics while maintaining manufacturing simplicity through a streamlined process sequence.
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 semiconductor device with stable electric characteristics and high reliability by compensating oxygen vacancies and preventing the entry of moisture and hydrogen, thereby reducing fluctuations in threshold voltage and improving overall performance.
Implementation Method 1
the oxide semiconductor layer is sandwiched between aluminum oxide films to suppress oxygen detachment from the oxide semiconductor layer
Implementation Method 2
it is possible to remove impurities containing hydrogen atoms (e.g., hydrogen, moisture, and the like) by performing heat treatment on the oxide semiconductor film
Implementation Method 3
by successively forming stacked films of the transistor in an in-line apparatus which is a fast cycle apparatus, impurity concentration at an interface between each layer can be extremely reduced
Implementation Method 4
subjected to first heat treatment and oxygen supplying treatment in the first in-line apparatus
Data Source
AI summary
In a method for manufacturing a transistor including an oxide semiconductor layer, a gate electrode is formed and then an aluminum oxide film, a silicon oxide film, and the oxide semiconductor film are successively formed in an in-line apparatus without being exposed to the air and are subjected to heating and oxygen adding treatment in the in-line apparatus. Then, the transistor is covered with another aluminum oxide film and is subjected to heat treatment, so that the oxide semiconductor film from which impurities including hydrogen atoms are removed and including a region containing oxygen at an amount exceeding that in the stoichiometric composition ratio. The transistor including the oxide semiconductor film is a transistor having high reliability in which the amount of change in threshold voltage of the transistor by the bias-temperature stress (BT test) can be reduced.