Semiconductor Well Region Electrode for Current Crowding Mitigation
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Solution Overview
Problem
The semiconductor device experiences low breakdown resistance due to current crowding during avalanche breakdown or short circuits, primarily because carriers flowing out of the main region into the well layer follow the upper surface of the semiconductor substrate, leading to uneven current distribution and reduced withstand voltage.
Innovation Solution
The introduction of a well region electrode in contact with the well region through a contact hole in the interlayer insulating film allows carriers to quickly exit, preventing current crowding and enhancing breakdown resistance by uniformly distributing current and increasing the withstand voltage. This is achieved by forming the well region deeper than the trenches in the main and current sense regions, with the well region electrode being either separate or integral with the main emitter electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the well layer is formed on the outer edge of the main region and insulated by the interlayer insulating film, then the structure is simple and easy to manufacture, but carriers flowing out of the main region into the well layer flow along the upper surface of the semiconductor substrate and easily effect current crowding in a specific location, resulting in low breakdown resistance
Solution Approach 1:
A well region electrode is introduced as an intermediary component between the well layer and the external circuit. This electrode provides a dedicated low-resistance path for carriers to exit the well layer, preventing them from flowing along the upper surface and causing current crowding. The well region electrode is connected to the main emitter electrode through a conductor, effectively mediating the carrier flow and eliminating the harmful current distribution pattern while maintaining manufacturing simplicity.
2Reliability
If the well layer depth is increased to prevent current crowding, then breakdown resistance improves, but the device complexity increases due to additional trenches and structures
Solution Approach 1:
Instead of increasing the well layer depth in the vertical dimension (which would require deeper trenches and increase complexity), the solution introduces a new horizontal dimension by adding the well region electrode on the upper surface. This electrode extends from the well layer through the interlayer insulating film to connect with the main emitter electrode, providing an alternative carrier exit path without modifying the vertical well layer depth or requiring additional deep trenches.
3Ease of manufacture
If carriers are allowed to flow along the upper surface of the semiconductor substrate, then the manufacturing process remains simple, but current crowding occurs in specific locations leading to reduced withstand voltage
Solution Approach 1:
The well region electrode serves as an intermediary that intercepts carriers before they can flow along the upper surface and cause current crowding. By providing a direct vertical path from the well layer to the main emitter electrode, the well region electrode eliminates the need for carriers to traverse the upper surface, thereby preventing current concentration and maintaining high withstand voltage while keeping the manufacturing process simple.
Data Source
AI summary
A semiconductor device disclosed herein is configured such that a well region including a well layer is disposed between a main region of a semiconductor substrate and a current sense region of the semiconductor substrate, that a well region electrode is disposed above the well region, and that the well layer and the well region electrode are in contact with each other through a contact hole formed in an interlayer insulating film.