MOSFET Perimeter Trench Structure for Source Ring Current Distribution
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Solution Overview
Problem
In semiconductor devices like MOSFETs, current concentration in the source ring region can lead to destruction, particularly due to high voltage and current handling, which existing designs fail to adequately prevent.
Innovation Solution
The semiconductor device incorporates a perimeter trench surrounding the active region with a second gate electrode and a source ring region connected to the source electrode, increasing the connection area and forming a channel around the trench to distribute current and prevent concentration on the source ring portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a source ring structure is used in a MOSFET, then the device can handle high voltage and current, but current concentration occurs in the source ring region leading to potential destruction
Solution Approach 1:
The source ring region is divided into multiple discrete source regions (first source region, second source region, third source region) with different impurity concentrations and geometries. This segmentation allows each region to handle current differently, preventing concentration at any single location while maintaining overall high power capability
Solution Approach 2:
Different regions of the source ring are assigned different impurity concentrations (higher in first source region, lower in second and third source regions) and different geometries (rectangular, L-shaped, U-shaped). This creates local quality variations that distribute current density evenly across the source ring, preventing hot spots while preserving high voltage handling
2Reliability
If the gate ring region is made larger to improve gate control, then voltage control is enhanced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The gate ring is segmented into multiple gate regions (first gate region, second gate region, third gate region) that can be independently formed and controlled. This segmentation provides flexible gate control over different portions of the channel without requiring a single large complex gate structure, simplifying manufacturing while maintaining control capability
Solution Approach 2:
The gate ring structure serves multiple functions: it controls the channel in the active region, provides edge termination, and influences current distribution in the source ring. By integrating these functions into a unified gate ring design with segmented regions, the device achieves enhanced control without proportional increases in complexity
Data Source
AI summary
A semiconductor device includes an active region as a region through which main current flows, an active region perimeter that surrounds the active region, and an edge termination region that surrounds the active region perimeter. The active region perimeter includes: a semiconductor substrate; a drift layer of a first conductivity type; a base region of a second conductivity type provided on an upper surface side of the drift layer; a source region of a first conductivity type selectively provided on an upper surface side of the base region; a perimeter trench including a contact region of the second conductivity type selectively provided, having at least a sidewall on the active region side in contact with the source region, and provided to pass through the base region; and a source ring region provided to be in contact with the contact region.