Nitride HEMT Heterojunction Structure for High Carrier Mobility
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Solution Overview
Problem
Current high electron mobility transistors (HEMTs) face challenges in achieving enhanced performance and integration with other components for diverse applications, particularly in achieving high carrier concentration and mobility, which limits their frequency and power handling capabilities.
Innovation Solution
A semiconductor device is developed with a substrate, multiple nitride semiconductor layers forming a heterojunction to create a two-dimensional electron gas (2DEG) region, along with specific gate conductors and passivation layers, enabling improved carrier mobility and frequency performance. The device includes a method for fabricating this structure using techniques like chemical vapor deposition and epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Si-based devices are used, then manufacturing simplicity is maintained, but high-frequency characteristics and carrier mobility are insufficient
Solution Approach 1:
The patent employs a composite material structure consisting of multiple nitride semiconductor layers (GaN and AlGaN) with different bandgaps to form a heterojunction. This composite structure enables high-frequency characteristics and high carrier mobility by creating a two-dimensional electron gas (2DEG) region at the interface, while maintaining compatibility with existing semiconductor manufacturing processes.
Solution Approach 2:
The invention implements local quality differentiation by creating distinct regions within the semiconductor device: a first nitride semiconductor layer (GaN) providing high electron mobility in the channel region, and a second nitride semiconductor layer (AlGaN) with greater bandgap forming the barrier layer. This spatial differentiation of material properties optimizes both high-frequency performance and manufacturing feasibility.
2Reliability
If single-layer nitride semiconductor structure is used, then manufacturing process is simple, but carrier concentration and mobility are limited
Solution Approach 1:
The patent utilizes composite nitride semiconductor materials with different compositions and bandgaps. The first nitride semiconductor layer (GaN) and second nitride semiconductor layer (AlGaN) form a heterojunction that generates high carrier concentration and mobility through polarization effects at the interface, achieving superior electrical properties without excessive structural complexity.
Solution Approach 2:
The invention transitions from a single-layer to a multi-layer vertical structure, adding the dimension of material composition variation. By stacking nitride semiconductor layers with different bandgaps vertically, the device achieves enhanced carrier mobility through the formation of a two-dimensional electron gas at the heterojunction interface.
3Reliability
If AlGaN layer is added to form heterojunction, then high-frequency performance is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the composition parameter of the AlGaN barrier layer, controlling the aluminum content to achieve the desired bandgap difference while maintaining manufacturability. By carefully adjusting the Al composition ratio and layer thickness parameters, the device achieves enhanced power handling capabilities without requiring excessively tight manufacturing tolerances.
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 semiconductor device exhibits enhanced high-frequency characteristics and power handling capabilities, outperforming traditional Si-based devices, making it suitable for next-generation power and RF applications.
Implementation Method 1
the polarization of the heterojunction forms a two-dimensional electron gas (2DEG) region in the channel layer for providing a channel for the carriers
Implementation Method 2
forming a first nitride semiconductor layer on the substrate, forming a second nitride semiconductor layer on the first nitride semiconductor layer
Implementation Method 3
forming a first nitride semiconductor layer on the substrate, forming a second nitride semiconductor layer on the first nitride semiconductor layer
Data Source
AI summary
The present disclosure relates to a semiconductor device and a fabrication method thereof. The semiconductor device includes a substrate, a first nitride semiconductor layer disposed on the substrate, a second nitride semiconductor layer disposed on the first nitride semiconductor layer and having a bandgap greater than that of the first nitride semiconductor layer. The semiconductor device further includes a first gate conductor disposed on a first region of the second nitride semiconductor layer, a passivation layer covering the first gate conductor, and a second gate conductor disposed on the passivation layer and on a second region of the second nitride semiconductor layer, wherein the first region is laterally spaced apart from the second region.