SiC Double-Layer Guard Ring Structure for Higher Breakdown Voltage
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Solution Overview
Problem
Silicon carbide semiconductor devices face reliability issues due to high-intensity electric fields at the oxide-silicon carbide interface, leading to surface charge accumulation and reduced breakdown voltage.
Innovation Solution
A semiconductor structure with a double-layer floating guard ring terminal is introduced, featuring a first guard ring structure adjacent to the top surface of the silicon carbide layer and a second guard ring structure below it, which helps to lower the electron peak position and reduce surface charge accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer guard ring structure is used, then the manufacturing process is simple, but the surface charge accumulation is not effectively reduced and breakdown voltage is limited
Solution Approach 1:
The guard ring structure is divided into two separate layers: a first guard ring structure adjacent to the top surface and a second guard ring structure below it. This segmentation allows each layer to independently manage electric field distribution at different depths, effectively reducing surface charge accumulation and increasing breakdown voltage without creating an overly complex single-structure design
Solution Approach 2:
The solution transitions from a two-dimensional planar guard ring to a three-dimensional multi-layer structure by adding vertical depth. The first and second guard ring structures are positioned at different vertical levels within the silicon carbide layer, creating a volumetric electric field management system that addresses surface charge accumulation more effectively than a single-plane structure
2Reliability
If the guard ring structure is placed adjacent to the top surface, then surface charge accumulation is addressed, but the electric field intensity at the oxide interface remains high
Solution Approach 1:
By introducing a vertical dimension with the second guard ring structure positioned below the first, the electric field is distributed across multiple depth levels. This three-dimensional arrangement allows the guard ring system to address surface charge accumulation at the top surface while simultaneously managing electric field intensity at deeper oxide interfaces, as each layer operates at its optimal vertical position
Data Source
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AI summary
A semiconductor structure includes a silicon carbide layer, which has a unit region and a termination region surrounding the unit region. A first guard ring structure is located in the termination region of the silicon carbide layer, and adjoins a top surface of the silicon carbide layer. The first guard ring structure may include at least one first guard ring well region. A second guard ring structure is located in the silicon carbide layer and below the first guard ring structure. The second guard ring structure may include at least one second guard ring well region, which corresponds to the at least one first guard ring well region in a vertical direction. A method for manufacturing the semiconductor structure is also provided.