Termination Structure Body Extension Regions for Power Transistors
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Solution Overview
Problem
Existing superjunction construction technologies for power transistors face limitations in pitch, leading to wasted semiconductor area and termination difficulties, which affect device reliability and yield, while also struggling to maintain low on-state resistance and high breakdown voltage.
Innovation Solution
The proposed electronic device features a termination structure with a body extension region, inner drain extension region, and floating doped regions to reduce electrical fields and enhance breakdown voltage, allowing for narrower designs that support higher drain-to-source voltages without compromising reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If existing superjunction construction technologies are used, then device area utilization is reduced due to limited pitch, but increasing pitch would reduce the number of trenches and affect voltage blocking capability
Solution Approach 1:
The patent introduces body extension regions that protrude from the trench bottoms into the semiconductor layer, creating a three-dimensional structure that extends beyond the traditional planar trench configuration. This dimensional extension allows the termination structure to effectively block voltage across a broader area without requiring increased pitch between trenches, thereby improving area utilization while maintaining voltage blocking capability.
Solution Approach 2:
The termination structure is segmented into multiple functional regions: trenches filled with insulating material, body extension regions protruding from trench bottoms, and drift regions. This segmentation allows each component to perform its specific function optimally - trenches provide physical separation and voltage blocking, while body extension regions enhance the blocking capability without requiring increased spacing between trenches.
2Reliability
If robust termination structures are used to maintain high breakdown voltage, then device complexity increases, but simplifying the structure would reduce breakdown voltage
Solution Approach 1:
The body extension regions serve multiple functions simultaneously: they extend the depletion region to enhance voltage blocking capability, they provide additional path for charge carrier generation during breakdown, and they work cooperatively with the trench structures to create an integrated termination system. This multi-functionality achieves high breakdown voltage without proportionally increasing structural complexity.
Solution Approach 2:
The body extension regions are positioned and dimensioned to create equipotential surfaces that distribute the electric field uniformly across the termination structure. By maintaining equipotential conditions, the structure achieves enhanced voltage blocking capability through a relatively simple geometric modification rather than complex multi-layer configurations.
3Area of moving object
If narrower termination structures are used to reduce area, then electrical field concentration increases reducing breakdown voltage, but wider structures would increase area usage
Solution Approach 1:
The body extension regions extend vertically from the trench bottoms into the drift region, creating a three-dimensional field distribution pattern. This vertical extension allows the termination structure to maintain narrow planar dimensions (saving area) while achieving effective voltage blocking through the extended depletion region that protrudes into the drift region, thereby distributing the electrical field more effectively.
Solution Approach 2:
The body extension regions act as intermediary structures between the trenches and the drift region. They provide a gradual transition for the electric field lines, preventing sharp field concentration at the trench edges while maintaining compact overall dimensions. This intermediary structure enables narrow termination structures to achieve adequate field distribution for high breakdown voltage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The termination structure achieves higher breakdown voltages and improved reliability by reducing electrical fields and allowing for narrower designs that maintain high performance across a range of drain-to-source voltages from 100 V to 900 V.
Implementation Method 1
a body extension region of the second conductivity type adjacent to the primary surface of the first semiconductor layer and spaced apart from the first trench
Data Source
AI summary
An electronic device can include a termination structure that includes a substrate, a semiconductor layer, and a first trench. The substrate includes a semiconductor material of a first conductivity type. The semiconductor layer has a second conductivity type opposite the first conductivity type and overlies the substrate and has a primary surface. The first trench extends through a majority of a thickness of the semiconductor layer. In an embodiment, a body extension region of the second conductivity type is adjacent to the primary surface and spaced apart from the first trench. In another embodiment, a doped region of the first conductivity type is adjacent to the primary surface and abuts the first trench. In a further embodiment, the termination structure can include a second trench extending through a majority of the thickness of the semiconductor layer and a doped region is spaced apart from the first and second trenches.