Trench Insulating Plug Structure for MOSFET Edge Breakdown Control
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Solution Overview
Problem
Current semiconductor devices, such as MOSFETs, face challenges in improving performance and preventing edge breakdown due to insufficient edge termination structures, particularly in power electronic applications where trench designs and field plates are not adequately effective in managing electric fields.
Innovation Solution
A semiconductor device with a trench structure in the edge termination region, featuring an electrically insulating layer lining the trench and an insulating plug extending across the trench width, forming an interface with the layer and having a surface coplanar with the substrate, which enhances insulation and prevents material penetration during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench structure is formed in the edge termination region, then edge breakdown is prevented, but the device complexity increases due to additional insulating layers and plugs
Solution Approach 1:
The insulating structure in the trench is segmented into two distinct parts: a first electrically insulating layer lining the trench walls and base, and a second electrically insulating plug filling the remaining trench space. This segmentation allows each layer to perform its specific function optimally while maintaining overall reliability and managing complexity through functional division.
Solution Approach 2:
Different regions of the trench are assigned different insulating materials with specific properties tailored to local requirements. The first insulating layer provides surface passivation and field management at the trench walls, while the second insulating plug provides bulk insulation and mechanical support in the trench center, optimizing performance for each local region.
2Ease of manufacture
If the upper surface of the plug is coplanar with the first major surface, then subsequent processing is simplified, but manufacturing precision requirements increase
Solution Approach 1:
The first electrically insulating layer is formed as a preliminary step before depositing the second insulating plug. This preliminary layer serves as a foundation that defines the trench boundaries and provides a reference plane, making it easier to achieve coplanar alignment of the plug upper surface with the substrate surface in subsequent processing steps.
Solution Approach 2:
The first electrically insulating layer that lines the trench walls and base also serves as a self-aligning reference for the second insulating plug. By forming the plug on top of this layer, the structure automatically ensures proper positioning and alignment, reducing the need for additional alignment steps and lowering manufacturing precision requirements.
Data Source
Figure 1A~1C
Figure 2A~2D
Figure 3
AI summary
In an exemplary embodiment, a semiconductor device comprises a semiconductor substrate having a first major surface, a trench positioned in the semiconductor substrate and having a width, a base and a side wall extending from the base to the first major surface, a first electrically insulating layer that lines the base and side wall of the trench and an electrically insulating plug that is positioned in the trench and that extends across the entire width of the trench. The plug has a lower surface that forms an interface with the first electrically insulating layer and an upper surface. The upper surface of the plug is coplanar with the first major surface of the semiconductor substrate or positioned within the trench.