GaN Junction Termination via Conductivity Modulation
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Solution Overview
Problem
Conventional methods for forming junction termination structures in semiconductor devices, particularly in GaN-based materials, face challenges such as high defect densities and limitations in thickness due to foreign substrates, leading to inefficient edge termination and increased off-state leakage current.
Innovation Solution
The method involves forming junction termination structures using ion implantation to modulate conductivity in GaN epitaxial layers, creating regions with varying conductivities to alleviate corner electrical fields and provide effective edge termination, thereby improving the breakdown voltage and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods for forming junction termination structures are used in GaN-based materials, then the device can be manufactured with standard processes, but high defect densities and limitations in thickness occur leading to inefficient edge termination and increased off-state leakage current
Solution Approach 1:
The patent applies local quality by creating regions with different conductivity types (n-type and p-type) in specific locations within the GaN epitaxial layer. Ion implantation is used to form localized junction termination regions with tailored electrical properties, allowing efficient edge termination in critical areas while maintaining low leakage current through appropriate conductivity modulation in those local regions.
2Reliability
If ion implantation is used to form junction termination structures, then conductivity modulation is achieved to alleviate corner electrical fields, but the process complexity increases
Solution Approach 1:
The patent employs parameter changes by varying the ion implantation conditions (ion type, energy, dose, and distribution) to achieve the desired conductivity modulation profile. By adjusting these parameters, the patent optimizes the electrical characteristics of the junction termination regions to enhance breakdown voltage while managing the inherent process complexity through controlled parameter selection.
3Reliability
If multiple regions with different conductivities are formed using ion implantation, then corner electrical fields are alleviated and breakdown characteristics are enhanced, but the manufacturing cost increases
Solution Approach 1:
The patent applies segmentation by dividing the junction termination structure into multiple distinct regions with different conductivity characteristics. Ion implantation creates separate n-type and p-type regions that work together to alleviate corner electrical fields. This segmented approach enhances breakdown characteristics by distributing the electrical stress management across multiple specialized zones rather than using a single uniform 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
This approach results in fully planar, cost-effective semiconductor devices with improved conductivity modulation, enhanced breakdown characteristics, and reduced off-state leakage current, enabling operation closer to parallel plane breakdown voltage.
Implementation Method 1
implanting ions into a first region of the second GaN epitaxial layer to form a first junction termination element characterized by a first conductivity less than a conductivity of the second GaN epitaxial layer and implanting ions into a second region of the second GaN epitaxial layer to form a second junction termination element characterized by a second conductivity less than the first conductivity
Data Source
AI summary
A semiconductor structure includes a GaN substrate having a first surface and a second surface opposing the first surface. The GaN substrate is characterized by a first conductivity type and a first dopant concentration. The semiconductor structure also includes a first GaN epitaxial layer of the first conductivity type coupled to the second surface of the GaN substrate and a second GaN epitaxial layer of a second conductivity type coupled to the first GaN epitaxial layer. The second GaN epitaxial layer includes an active device region, a first junction termination region characterized by an implantation region having a first implantation profile, and a second junction termination region characterized by an implantation region having a second implantation profile.