GaN Floating Guard Rings for Edge Termination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for creating edge termination structures in semiconductor devices, particularly for high-voltage applications, face challenges such as field crowding and uncontrollable breakdown at the device edges due to limitations in materials like silicon carbide substrates, which restrict GaN layer thickness and increase defect densities.
Innovation Solution
The method involves forming edge termination structures using ion implantation into gallium-nitride (GaN) based epitaxial layers to electrically isolate device regions from edge termination regions, providing a high degree of electrical isolation and allowing for fully planar structures without etched sidewalls, thus alleviating field crowding and enhancing breakdown voltage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicon carbide substrates are used for high-voltage semiconductor devices, then the devices can be manufactured with existing processes, but the GaN layer thickness is restricted and defect densities increase
Solution Approach 1:
The patent changes the substrate material parameter from silicon carbide to GaN, enabling thicker active layers and reduced defect densities. This material parameter change allows the GaN layer thickness to exceed what is possible on silicon carbide substrates, directly improving breakdown voltage performance while maintaining manufacturing feasibility through established GaN epitaxial processes
2Reliability
If conventional edge termination structures are used, then device regions can be separated from edge termination regions, but field crowding and uncontrollable breakdown occur at device edges
Solution Approach 1:
The patent introduces a vertical dimension to the edge termination structure by forming an elevated termination region that rises above the main device region. This dimensional change redistributes the electric field in the vertical direction, preventing field crowding at the horizontal edges and enabling controlled breakdown behavior at the device periphery
3Reliability
If ion implantation is used to form floating guard rings, then electrical isolation between device regions and edge termination regions is achieved, but the process complexity increases
Solution Approach 1:
The patent merges the floating guard ring formation with the edge termination structure fabrication by using the same ion implantation process for both. The elevated termination region and the floating guard rings are created in a coordinated manner through combined implantation steps, achieving electrical isolation while reducing the number of separate fabrication processes required
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 enables semiconductor devices to operate closer to their parallel plane breakdown voltage, reducing off-state leakage current and manufacturing costs, while exploiting the superior properties of GaN materials like high critical electric field and electron mobility.
Implementation Method 1
implanting ions into a first region of the second GaN epitaxial layer to electrically isolate a second region of the second GaN epitaxial layer from a third region of the second GaN epitaxial layer
Data Source
AI summary
A method for fabricating an edge termination structure includes providing a substrate having a first surface and a second surface and a first conductivity type, forming a first GaN epitaxial layer of the first conductivity type coupled to the first surface of the substrate, and forming a second GaN epitaxial layer of a second conductivity type opposite to the first conductivity type. The second GaN epitaxial layer is coupled to the first GaN epitaxial layer. The method also includes implanting ions into a first region of the second GaN epitaxial layer to electrically isolate a second region of the second GaN epitaxial layer from a third region of the second GaN epitaxial layer. The method further includes forming an active device coupled to the second region of the second GaN epitaxial layer and forming the edge termination structure coupled to the third region of the second GaN epitaxial layer.