Nitride Semiconductor Gate Insulator with Nitrogen Gradient
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Solution Overview
Problem
In semiconductor devices using nitride semiconductors, charge injection into the insulating layer leads to degradation of characteristics such as threshold voltage fluctuations, increased leakage current, and elevated on-resistance, which are not effectively addressed by existing technologies.
Innovation Solution
A semiconductor device with a gate insulating layer comprising a silicon oxide film and an aluminum oxynitride film, where the nitrogen concentration gradient in the aluminum oxynitride film is strategically controlled to suppress charge injection, achieving a reversed fixed dipole direction at the interface between the silicon oxide and aluminum oxynitride films, thereby reducing threshold voltage fluctuations and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulating layer is used in nitride semiconductor transistors, then the device structure is simple, but charge injection occurs leading to threshold voltage fluctuation, increased leakage current, and increased on-resistance
Solution Approach 1:
The gate insulating layer is divided into multiple distinct layers: a first insulating layer (Aluminum Oxynitride) in contact with the nitride semiconductor layer, and a second insulating layer (Silicon Oxide) on top of the first layer. This segmentation allows each layer to perform specific functions - the first layer suppresses charge injection while the second layer provides electrical insulation, thereby resolving the contradiction between reliability and device simplicity.
Solution Approach 2:
The patent employs a composite gate insulating layer structure combining Aluminum Oxynitride and Silicon Oxide materials. The Aluminum Oxynitride layer specifically addresses charge injection issues due to its material properties, while the Silicon Oxide layer provides robust electrical insulation. This composite approach improves threshold voltage stability without requiring overly complex device architecture.
2Reliability
If silicon oxide film is used alone as the gate insulating layer, then the manufacturing process is simple, but charge injection into the film causes threshold voltage fluctuation and increased leakage current
Solution Approach 1:
The gate insulating layer is segmented into two layers formed by sequential deposition processes. The first layer (Aluminum Oxynitride) is deposited using ALD or PECVD, followed by the second layer (Silicon Oxide) deposited by PECVD or CVD. This segmentation enables charge injection suppression while maintaining manufacturing feasibility through established semiconductor fabrication techniques.
Solution Approach 2:
The patent uses a composite gate insulating layer combining Aluminum Oxynitride and Silicon Oxide. The Aluminum Oxynitride layer specifically suppresses charge injection due to its material properties, while the Silicon Oxide layer provides electrical insulation. This composite structure improves reliability without requiring exotic materials or overly complex fabrication 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
The solution effectively suppresses charge injection into the gate insulating layer, stabilizing the threshold voltage and reducing leakage current, thereby improving the overall performance and reliability of nitride semiconductor transistors.
Implementation Method 1
achieving a reversed fixed dipole direction at the interface between the silicon oxide and aluminum oxynitride films
Implementation Method 2
suppress charge injection, achieving a reversed fixed dipole direction at the interface
Data Source
AI summary
A semiconductor device according to an embodiment includes a first nitride semiconductor layer; a second nitride semiconductor layer on the first nitride semiconductor layer; a first electrode and a second electrode disposed on or above the first nitride semiconductor layer; a gate electrode above the first nitride semiconductor layer; and a gate insulating layer, the gate insulating layer including a silicon oxide film and an aluminum oxynitride film, the aluminum oxynitride film disposed between the first nitride semiconductor layer and the silicon oxide film, a first atomic ratio of nitrogen relative to a sum of oxygen and nitrogen at a first position in the aluminum oxynitride film being higher than a second atomic ratio of nitrogen relative to a sum of oxygen and nitrogen at a second position in the aluminum oxynitride film, and the second position being closer to the silicon oxide film than the first position.