SiC Semiconductor Device Segmented Diffusion Layer
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Solution Overview
Problem
Conventional trench gate semiconductor devices experience excessive voltage drop and electric field on the gate insulating film due to displacement current flowing from the terminal region into the active region, leading to potential breakdown of the gate insulating film.
Innovation Solution
The semiconductor device design includes a diffusion protective layer with extensions that are separated from the terminal protective layer, preventing displacement current from flowing into the active region and reducing excessive electric fields on the gate insulating film by electrically connecting the diffusion and terminal protective layers only through the source electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the diffusion protective layer is formed continuously from the gate trench to the terminal trench, then the withstand voltage is improved, but displacement current flows into the active region causing excessive voltage drop and electric field on the gate insulating film
Solution Approach 1:
The diffusion protective layer is segmented into two separate regions: a first diffusion protective layer in the active region and a second diffusion protective layer in the terminal region. These two layers are electrically connected through the source electrode rather than being continuously connected. This segmentation prevents displacement current from flowing from the terminal region into the active region through the diffusion protective layer, thereby eliminating excessive voltage drop and excessive electric field on the gate insulating film while still maintaining adequate withstand voltage through the source electrode connection.
2Power
If the diffusion protective layer extensions connect to the terminal protective layer, then current conduction is improved, but displacement current causes excessive voltage drop across the diffusion protective layer
Solution Approach 1:
The source electrode serves as an intermediary connection between the first diffusion protective layer and the second diffusion protective layer. Instead of direct connection through the diffusion protective layer extensions, the source electrode mediates the electrical connection. This intermediary connection path has lower resistance and prevents displacement current from causing excessive voltage drop, while still enabling proper current conduction for device operation.
Data Source
AI summary
A silicon carbide semiconductor device includes a diffusion protective layer provided below a gate insulating film, a gate line provided on an insulation film on the bottom face of a terminal trench and electrically connected to a gate electrode, the terminal trench being located more toward the outer side than the gate trench, a gate pad joined to the gate line in the terminal trench, a terminal protective layer provided below the insulation film on the bottom face of the terminal trench, and a source electrode electrically connected to a source region, the diffusion protective layer, and the terminal protective layer. The diffusion protective layer has first extensions that extend toward the terminal protective layer and that are separated from the terminal protective layer. This configuration inhibits an excessive electric field from being applied to the gate insulating film provided on the bottom face of the gate trench.