SiC Source Trench Sidewall Contact for Reliable Source Grounding
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Solution Overview
Problem
Existing SiC semiconductor devices face challenges in appropriately source-grounding the source region within a source trench structure, which affects the device's performance and reliability.
Innovation Solution
The SiC semiconductor device includes a source trench with a side wall contact portion of the source electrode connected to the source region, allowing for effective source-grounding by electrically connecting the source region to the source electrode exposed from the side wall of the source trench, along with a body region of a second conductivity type and a source region of the first conductivity type, ensuring proper electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a source trench structure is used in SiC semiconductor devices, then device integration and insulation are improved, but appropriate source-grounding of the source region becomes difficult to achieve
Solution Approach 1:
The patent transitions from conventional planar source grounding to three-dimensional side wall contact grounding. The source electrode contacts the source region through the side wall of the source trench rather than through the bottom, utilizing the vertical dimension to achieve effective grounding while maintaining the trench structure's insulation benefits.
Solution Approach 2:
The patent introduces a source insulating layer as an intermediary substance coating the inner wall of the source trench. This insulating layer enables the source electrode to contact the source region through the side wall while preventing unwanted electrical connections between the source electrode and the drift region, thus achieving both grounding and insulation requirements.
2Reliability
If the source electrode is embedded in the source trench across an insulating layer, then insulation between source and drain is improved, but electrical connection between source region and source electrode becomes insufficient
Solution Approach 1:
The source insulating layer is applied selectively to specific regions: it coats the inner wall of the source trench to provide insulation, but intentionally leaves the side wall contact region exposed or removes the insulating layer in that area. This local differentiation enables both insulation where needed and electrical connection where required.
Solution Approach 2:
The source trench structure is segmented into distinct functional zones: the upper portion with insulating layer coverage for insulation, and the side wall contact portion for electrical connection. This segmentation allows the single source trench structure to simultaneously fulfill both insulation and grounding functions.
Data Source
AI summary
An SiC semiconductor device includes an SiC semiconductor layer of a first conductivity type having a main surface, a source trench formed in the main surface and having a side wall and a bottom wall, a source electrode embedded in the source trench and having a side wall contact portion in contact with a region of the side wall of the source trench at an opening side of the source trench, a body region of a second conductivity type formed in a region of a surface layer portion of the main surface along the source trench, and a source region of the first conductivity type electrically connected to the side wall contact portion of the source electrode in a surface layer portion of the body region.