Oxide Semiconductor Transistor Structure for Hydrogen-Stable Operation
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Solution Overview
Problem
Existing semiconductor transistors face challenges in achieving stable electrical characteristics, low power consumption, and high reliability, particularly when using oxide semiconductors as the semiconductor layer.
Innovation Solution
The transistor design includes an insulating layer containing excess oxygen and a conductive layer to absorb hydrogen, combined with a manufacturing process that minimizes exposure to air, and employs a surrounded-channel structure with a gate and backgate electrode configuration to enhance electrical stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxide semiconductor is used for semiconductor layer, then field-effect mobility is improved, but electrical characteristics stability deteriorates due to hydrogen and water contamination
Solution Approach 1:
The patent applies preliminary action by forming a protective insulating layer containing excess oxygen (such as silicon oxide or silicon nitride) over the oxide semiconductor layer before any potential contamination can occur. This layer is prepared in advance to prevent hydrogen and water from reaching the semiconductor layer during subsequent manufacturing steps or device operation, thereby maintaining electrical characteristics stability while preserving high field-effect mobility.
Solution Approach 2:
The patent introduces an intermediary protective layer (insulating layer with excess oxygen) that acts as a barrier between the oxide semiconductor layer and external contaminants. This intermediary layer contains excess oxygen that can actively scavenge any hydrogen or water molecules attempting to penetrate through, preventing direct contact between contaminants and the semiconductor layer, thus resolving the contradiction between maintaining high mobility and ensuring stability.
2Ease of manufacture
If conventional transistor structure is used, then manufacturing simplicity is maintained, but power consumption increases due to high leakage current in off state
Solution Approach 1:
The patent applies parameter changes by modifying the protective insulating layer to contain excess oxygen beyond stoichiometric requirements. This excess oxygen parameter change creates active oxygen sites that can trap and neutralize hydrogen and water contaminants, dramatically reducing leakage current in the off state. The change in oxygen content parameter transforms the insulating layer from a passive barrier to an active contaminant scavenger, enabling low power consumption while maintaining manufacturing simplicity.
3Adaptability or versatility
If oxide semiconductor layer is exposed to air during manufacturing, then manufacturing process flexibility is improved, but hydrogen concentration in semiconductor layer increases
Solution Approach 1:
The patent applies preliminary action by forming the oxygen-excess insulating protective layer over the oxide semiconductor layer before any air exposure occurs during subsequent manufacturing steps. This pre-formed protective barrier ensures that even when the device is exposed to air for manufacturing flexibility reasons, hydrogen and water from the air cannot penetrate to the semiconductor layer, thus maintaining precise hydrogen concentration control while allowing manufacturing process flexibility.
Solution Approach 2:
The patent introduces an intermediary protective insulating layer that mediates between the oxide semiconductor layer and the air environment. This intermediary layer contains excess oxygen that actively scavenges hydrogen and water molecules from the air, preventing them from reaching the semiconductor layer. This allows the device to be exposed to air during manufacturing without compromising hydrogen concentration precision, thereby achieving both manufacturing flexibility and manufacturing precision.
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 design provides transistors with favorable electrical characteristics, stable operation, low power consumption, and high reliability, while enabling high integration and resistance to environmental stress.
Implementation Method 1
an insulating layer containing excess oxygen is formed over the oxide semiconductor layer
Implementation Method 2
a conductive layer with a function of absorbing hydrogen is used for a source electrode and a drain electrode
Data Source
AI summary
An object is to provide a highly reliable transistor. In a bottom-gate transistor including an oxide semiconductor layer as a semiconductor layer where a channel is formed, an insulating layer containing excess oxygen is formed over the oxide semiconductor layer, and then an insulating layer through which impurities do not easily pass is formed without exposure to the air. As the insulating layer through which impurities do not easily pass, an aluminum oxide layer or the like can be used. When a conductive layer with a function of absorbing hydrogen is used for a source electrode and a drain electrode, the amount of hydrogen in the oxide semiconductor layer can be reduced.