GaN HEMT Resurf Layer Alleviates Lateral Electric Field
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Solution Overview
Problem
Semiconductor devices, such as switching devices and diodes, face a trade-off between breakdown voltage and on-resistance, with silicon-based devices nearing their performance limits, necessitating the use of wide bandgap materials like GaN and SiC to improve these characteristics.
Innovation Solution
A semiconductor device structure incorporating a first GaN-based semiconductor layer, a second GaN-based semiconductor layer with a larger bandgap, and p-type GaN-based layers, along with a recessed gate structure and resurf layers, is employed to enhance breakdown voltage and reduce on-resistance, utilizing epitaxial growth and specific electrode configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon-based devices are used, then manufacturing maturity and ease of fabrication are maintained, but breakdown voltage and on-resistance performance reach their limits
Solution Approach 1:
The patent employs a composite structure combining silicon substrate with GaN-based semiconductor layers. The silicon substrate provides mechanical support and成熟的 manufacturing infrastructure, while the GaN layers deliver high breakdown voltage and low on-resistance performance. This composite approach allows leveraging both materials' advantages to resolve the contradiction between manufacturing ease and performance improvement.
Solution Approach 2:
The device is segmented into distinct functional layers: silicon substrate, buffer layer, channel layer, and barrier layer. Each layer is optimized independently for its specific function, allowing the silicon substrate to handle manufacturing requirements while the GaN layers handle performance requirements. This segmentation enables separate optimization of manufacturing ease and device performance.
2Reliability
If wider bandgap materials like GaN are used, then breakdown voltage and on-resistance are improved, but device structure and manufacturing process become more complex
Solution Approach 1:
The patent applies local quality by creating a heterostructure where different GaN layers have specifically tailored properties: the channel layer is optimized for carrier transport with appropriate thickness and doping, while the barrier layer is optimized for field confinement with higher aluminum content. This local optimization of each layer's properties achieves low on-resistance without requiring excessive overall device complexity.
Solution Approach 2:
The patent utilizes parameter changes in the GaN layer composition, particularly varying the aluminum content in AlGaN barrier layers to control the two-dimensional electron gas density and field effect mobility. By adjusting these parameters systematically, the device achieves optimal on-resistance performance while maintaining a manageable structural complexity.
3Reliability
If GaN-based HEMT structure is implemented, then high breakdown voltage is achieved, but lateral electric field concentration occurs at gate edges
Solution Approach 1:
The patent converts the harmful lateral electric field concentration at gate edges into a beneficial effect by introducing p-type GaN layers that generate holes. These holes neutralize the excessive electric field at the gate edges, preventing premature breakdown while maintaining the high breakdown voltage capability of the GaN HEMT structure. The harmful field concentration is thus transformed into a mechanism for field control and reliability enhancement.
Solution Approach 2:
The p-type GaN layers act as intermediaries between the high-field region under the gate and the drain region. These layers mediate the electric field distribution by generating holes that compensate for the lateral field concentration, thereby protecting the device from field-induced breakdown while preserving the high breakdown voltage特性 of the GaN structure.
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 proposed structure achieves high breakdown voltage and low on-resistance by alleviating lateral electric fields, thereby improving the performance of GaN-based HEMT devices beyond the limitations of silicon-based devices.
Implementation Method 1
a second GaN based semiconductor layer disposed on the first GaN based semiconductor layer, the second GaN based semiconductor layer having a bandgap larger than a bandgap of the first GaN based semiconductor layer
Implementation Method 2
a first GaN based semiconductor layer; a second GaN based semiconductor layer disposed on the first GaN based semiconductor layer, the second GaN based semiconductor layer having a bandgap larger than a bandgap of the first GaN based semiconductor layer
Implementation Method 3
a p-type third GaN based semiconductor layer disposed between the second GaN based semiconductor layer and an end portion on the drain electrode side of the gate electrode, the gate insulating film being disposed between the gate electrode and the third GaN based semiconductor layer
Data Source
AI summary
A semiconductor device includes: a first GaN based semiconductor layer (hereinafter abbreviated as GaN layer); a second GaN layer on the first GaN layer and having a bandgap larger than that of the first GaN layer; a source electrode on the second GaN layer; a drain electrode on the second GaN layer; a gate electrode between the source electrode and the drain electrode, a gate insulating film between the gate electrode and the first GaN layer, a film thickness of the second GaN layer between the gate electrode and the first GaN layer being thinner than that of the second GaN layer between the source electrode and the first GaN layer; and a p-type third GaN layer between the second GaN layer and an end portion on the drain electrode side of the gate electrode, the gate insulating film between the gate electrode and the third GaN layer.