Vertical MOSFET Drift Region Layout for High Breakdown Voltage
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Solution Overview
Problem
Existing semiconductor devices, such as vertical MOSFETs, face challenges in increasing breakdown voltage while maintaining low on-resistance.
Innovation Solution
The semiconductor device incorporates a high resistance part with tensile stress in the n−-type drift region, arranged in an equilateral triangular configuration with structure bodies, to enhance breakdown voltage and carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breakdown voltage is increased in vertical MOSFETs, then the device can handle higher voltages, but the on-resistance increases which reduces efficiency
Solution Approach 1:
The patent introduces a high resistance part with tensile stress in a specific region of the drift region, creating local variation in electrical properties. This localized modification allows the majority of the drift region to maintain low resistance while the high resistance part controls the breakdown voltage characteristics, thus resolving the contradiction between high breakdown voltage and low on-resistance.
Solution Approach 2:
The patent changes the physical and electrical parameters of the drift region by introducing tensile stress through the high resistance part. This parameter change affects both the breakdown voltage (improving it) and the carrier mobility in surrounding regions (reducing on-resistance), simultaneously addressing both contradictory requirements.
2Reliability
If the drift region is modified to increase breakdown voltage, then higher voltage handling is achieved, but carrier mobility may be reduced increasing on-resistance
Solution Approach 1:
The high resistance part with tensile stress is introduced locally in the drift region rather than modifying the entire region. This localized approach allows carrier mobility to be maintained in the low resistance drift region while the high resistance part provides the necessary breakdown voltage enhancement through its specific electrical properties.
Solution Approach 2:
The patent converts the potentially harmful effect of high resistance (which would normally increase on-resistance) into a beneficial feature by strategically placing the high resistance part with tensile stress. The tensile stress induces beneficial strain in surrounding regions that enhances carrier mobility, thus converting the harmful high resistance property into a benefit for both breakdown voltage and carrier mobility.
3Reliability
If structure bodies are added to enhance breakdown voltage, then device reliability improves, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the high resistance part: it provides breakdown voltage enhancement, introduces tensile stress for carrier mobility improvement, and acts as an electrical isolation structure. By combining these functions into a single integrated structure rather than adding separate components, the patent enhances reliability while minimizing increases in device complexity.
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
This configuration effectively suppresses the reduction of breakdown voltage and reduces on-resistance by improving carrier mobility through tensile strain, while maintaining efficient depletion layer extension.
Implementation Method 1
a high resistance part (30) having a higher electrical resistance than the n−-type drift region (1) and having tensile stress
Implementation Method 2
This configuration effectively suppresses the reduction of breakdown voltage and reduces on-resistance by improving carrier mobility through tensile strain, while maintaining efficient depletion layer extension
Data Source
AI summary
A semiconductor device according to an embodiment includes first to third semiconductor regions, a structure body, a gate electrode, and a high resistance part. The structure body includes an insulating part and a conductive part. The insulating part is arranged with the third semiconductor region, the second semiconductor region, and a portion of the first semiconductor region. The conductive part is located in the insulating part. The conductive part includes a portion facing the first semiconductor region. The high resistance part is located in the first semiconductor region and has a higher electrical resistance than the first semiconductor region. A plurality of the structure bodies includes first to third structure bodies. The second and third structure bodies are next to the first structure body. The high resistance part overlaps a circle center of an imaginary circle passing through centers of the first to third structure bodies.