SiC MOSFET Gate Trench Layout for Short-Circuit Resistance
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Solution Overview
Problem
Conventional silicon carbide MOSFETs lack sufficient short-circuit resistance due to discontinuous arrangement of contact regions.
Innovation Solution
The silicon carbide semiconductor device incorporates a gate trench structure with an electric field relaxation region and a connection region that overlaps a virtual straight line, enhancing short-circuit resistance by increasing electrical resistance at narrow portions and limiting current paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If contact regions are discontinuously arranged along a gate trench, then device structure is simplified and manufacturing is easier, but short-circuit resistance is insufficient
Solution Approach 1:
The contact region is divided into multiple discrete contact regions arranged along the gate trench in plan view. This segmentation allows the contact region to provide sufficient short-circuit resistance through its distributed structure while maintaining ease of manufacture through a straightforward arrangement pattern that aligns with the gate trench geometry
Solution Approach 2:
The contact regions are arranged not only in the vertical direction but also distributed along the gate trench in plan view, adding a horizontal dimension to the contact region configuration. This multi-dimensional arrangement enhances short-circuit resistance by providing multiple current paths while keeping the structure manufacturable
2Reliability
If electric field relaxation region and connection region are positioned to overlap a virtual straight line, then short-circuit resistance is enhanced, but device structure becomes more complex
Solution Approach 1:
The electric field relaxation region and connection region are positioned to overlap a virtual straight line extending in the first direction, creating an equipotential arrangement that enhances short-circuit resistance. This linear alignment simplifies the electrical field distribution while providing sufficient resistance against short-circuit currents
Solution Approach 2:
The connection region serves multiple functions: it electrically connects the contact region to the electric field relaxation region, provides a current path, and when positioned to overlap the virtual straight line, enhances short-circuit resistance. This multi-functionality reduces the need for additional structures, thereby managing device complexity
3Reliability
If source region is separated from drift region, then device reliability is improved, but carrier supply efficiency decreases
Solution Approach 1:
The body region acts as an intermediary between the source region and the drift region. The source region is separated from the drift region by the body region, which improves device reliability by preventing direct contact. Meanwhile, carriers can still be supplied efficiently through the body region, maintaining productivity despite the separation
Data Source
AI summary
A silicon carbide semiconductor device includes a silicon carbide substrate having first and second main surfaces and including an electric field relaxation region and a connection region. A gate trench provided in the first main surface is defined by side surfaces and a bottom surface. The electric field relaxation region is a second conductivity type and provided between the bottom surface and the second main surface, and the connection region is the second conductivity type and electrically connects a contact region including first and second regions to the electric field relaxation region. In plan view, the gate trench and the electric field relaxation region are located on a virtual straight line. The first region is in contact with the connection region on the virtual straight line, and the second region is provided on a position where the source region is sandwiched between the gate trench and the second region.