Oxide Semiconductor Transistor with Oxygen-Releasing Insulator
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Solution Overview
Problem
Transistors using oxide semiconductors face reliability issues due to high variability in electrical characteristics and a tendency towards normally-on characteristics, making it difficult to create logic circuits and driver circuits effectively.
Innovation Solution
A semiconductor device structure is developed with a specific insulator configuration, including a second insulator with high oxygen release properties and a third insulator with excess oxygen, which helps stabilize the oxide semiconductor by reducing oxygen vacancies and preventing hydrogen diffusion, thereby improving reliability and achieving normally-off characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transistor including an oxide semiconductor is used, then the transistor can be operated at higher speed and manufactured more easily, but the reliability is low due to high possibility of change in electrical characteristics
Solution Approach 1:
The patent applies preliminary action by forming an insulator layer containing excess oxygen before forming the oxide semiconductor layer. This excess oxygen is released during heating to fill oxygen vacancies in the oxide semiconductor, preventing electrical characteristic changes before they occur. The insulator layer is prepared in advance with the specific function of oxygen supply to ensure reliability.
Solution Approach 2:
The insulator layer containing excess oxygen acts as an intermediary between the external environment and the oxide semiconductor. It mediates the oxygen supply to the oxide semiconductor, releasing oxygen when heated to maintain the oxide semiconductor's electrical characteristics without direct exposure to external oxygen sources.
2Reliability
If a transistor including an oxide semiconductor is used, then it has extremely low leakage current in off state, but it tends to have normally-on characteristics making it difficult to provide logic circuits
Solution Approach 1:
The patent changes the oxygen concentration parameter in the oxide semiconductor by using an insulator layer with excess oxygen. This parameter change fills oxygen vacancies, which modifies the electrical characteristics to achieve both low leakage current and proper normally-off behavior. The oxygen concentration is precisely controlled through the insulator layer's oxygen release properties.
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 solution enhances the reliability of oxide semiconductor transistors by reducing oxygen vacancies and hydrogen diffusion, leading to stable electrical characteristics, low off-state current, and low power consumption, enabling the creation of reliable logic circuits and driver circuits.
Implementation Method 1
the amount of oxygen released from the second insulator when converted into oxygen molecules is larger than or equal to 1×10^14 molecules/cm² and smaller than 1×10^16 molecules/cm² in thermal desorption spectroscopy at a surface temperature of a film of the second insulator of higher than or equal to 50° C. and lower than or equal to 500° C.
Implementation Method 2
helps stabilize the oxide semiconductor by reducing oxygen vacancies
Implementation Method 3
preventing hydrogen diffusion
Data Source
AI summary
A semiconductor device includes a first insulator, a transistor over the first insulator, a second insulator over the transistor, and a third insulator over the second insulator. The transistor includes an oxide semiconductor. The amount of oxygen released from the second insulator when converted into oxygen molecules is larger than or equal to 1×1014 molecules/cm2 and smaller than 1×1016 molecules/cm2 in thermal desorption spectroscopy at a surface temperature of a film of the second insulator of higher than or equal to 50° C. and lower than or equal to 500° C. The second insulator includes oxygen, nitrogen, and silicon.