Mg-Doped AlGaN Layer Structure for Stable GaN Threshold Voltage
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving stable threshold voltage and high electron mobility due to fluctuations in manufacturing processes, particularly in the magnesium concentration profiles of GaN layers, which affect the performance and reliability of transistors.
Innovation Solution
A semiconductor device with a first semiconductor layer comprising magnesium and Alx1Ga1-x1N, structured into regions with varying magnesium concentrations, where the concentration decreases step-wise in the second region and remains low in the third region, is manufactured using specific ammonia partial pressures to control magnesium incorporation and stabilize the threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If magnesium concentration is increased in GaN layers to improve electron mobility, then electron mobility is improved, but threshold voltage becomes unstable due to manufacturing fluctuations
Solution Approach 1:
The GaN layer is divided into multiple regions with different magnesium concentration profiles. The first region has a first magnesium concentration profile, the second region has a second magnesium concentration profile, and the third region has a third magnesium concentration profile. This segmentation allows different portions of the layer to serve different functions: some regions optimized for electron mobility while others provide threshold voltage stability, thereby resolving the contradiction between improving electron mobility and maintaining threshold voltage stability.
Solution Approach 2:
Different regions of the GaN layer are assigned different magnesium concentration characteristics tailored to their specific functional requirements. The first region through third region each have distinct magnesium concentration profiles optimized for their local roles in the device structure. This local quality approach enables simultaneous optimization of electron mobility in certain regions and threshold voltage stability in others, resolving the fundamental contradiction between these two performance parameters.
2Speed
If magnesium concentration profile is optimized for high electron mobility, then electron mobility improves, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The complex magnesium concentration profile is segmented into three distinct regions, each with its own concentration characteristics. This segmentation simplifies the manufacturing process by breaking down the complex task of creating an optimized profile into three manageable steps, where each region can be controlled independently. This resolves the contradiction by making the manufacturing process more controllable while still achieving the desired electron mobility optimization.
Solution Approach 2:
The first region is formed with its specific magnesium concentration profile before forming the second and third regions. This preliminary action establishes a foundation that guides subsequent manufacturing steps, allowing each subsequent region to be built upon a already-established structure. This sequential approach improves manufacturing precision by providing clear reference points and reducing the complexity of simultaneous multi-parameter control.
3Stability of the object's composition
If step-wise magnesium concentration decrease is implemented to stabilize threshold voltage, then threshold voltage stability improves, but device complexity increases
Solution Approach 1:
The third region is designed with a specific magnesium concentration profile that is locally optimized for providing threshold voltage stability. By concentrating the threshold voltage stabilization function in this specific local region with distinct concentration characteristics, the overall device structure maintains relative simplicity while achieving the desired stability. This local quality approach avoids the need for complex modifications throughout the entire device structure.
Solution Approach 2:
The device structure is segmented into three functional regions, each with a defined magnesium concentration profile. This segmentation provides a clear, modular framework that simplifies the overall device design and manufacturing process. Each segment can be independently optimized and controlled, reducing the complexity of managing the entire device as a single complex system while still achieving threshold voltage stability through the coordinated action of all three regions.
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 stabilizes the threshold voltage and enhances electron mobility by controlling magnesium concentration gradients, improving the tolerance to manufacturing fluctuations and ensuring reliable transistor operation.
Implementation Method 1
a first semiconductor layer including magnesium and Alx1Ga1-x1N
Implementation Method 2
forming a first semiconductor layer on the substrate by using a gas. The gas includes ammonia, a raw material including gallium, and a raw material including magnesium
Data Source
AI summary
According to one embodiment, a semiconductor device includes a substrate, and a first semiconductor layer including magnesium and Alx1Ga1-x1N. The first semiconductor layer includes first, second, and third regions. The first region is between the substrate and the third region. The second region is between the first and third regions. A first concentration of magnesium in the first region is greater than a third concentration of magnesium in the third region. A second concentration of magnesium in the second region decreases along a first orientation. The first orientation is from the substrate toward the first semiconductor layer. A second change rate of a logarithm of the second concentration with respect to a change of a position along the first orientation is greater than a third change rate of a logarithm of the third concentration with respect to the change of the position along the first orientation.