Hybrid SiC Power Device Structure for High Voltage Reliability
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Solution Overview
Problem
Silicon-based power metal oxide semiconductor field-effect transistors (MOSFETS) are approaching their physical limits due to increasing operating speed and power loss requirements, and wide bandgap semiconductor devices like silicon carbide (SiC) face reliability issues with high gate bias voltage and electrical characteristics, making it difficult to interface and control them effectively.
Innovation Solution
A hybrid silicon carbide (SiC) device structure is developed, comprising a first SiC substrate with multiple conductivity type layers and a second device structure bonded to it, including a switching device on a different substrate, to form a hybrid power device that addresses the reliability issues and enhances voltage handling and switching frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based power MOSFETs are used, then fabrication process maturity and current handling capability are improved, but operating speed and power loss performance deteriorate due to approaching physical limits
Solution Approach 1:
The patent employs a hybrid device structure combining silicon-based control circuitry with wide bandgap semiconductor power switching elements. This composite approach allows the silicon portion to provide mature fabrication benefits while the wide bandgap section delivers superior operating speed and reduced power loss, effectively resolving the contradiction between manufacturing maturity and performance limitations.
2Productivity
If wide bandgap semiconductor devices like SiC are used, then operating speed and voltage handling capability are improved, but reliability deteriorates due to high gate bias voltage requirements
Solution Approach 1:
The patent divides the power device into separate functional sections: a control section fabricated in mature silicon technology with lower voltage requirements, and a power switching section using wide bandgap materials for high-speed operation. This segmentation isolates the high gate bias voltage stress to specific regions, improving overall device reliability while maintaining high switching frequencies in the power section.
Solution Approach 2:
The patent introduces intermediate coupling structures and interface layers between the silicon control circuitry and wide bandgap power devices. These intermediary elements buffer the electrical stress and signal transitions, protecting the wide bandgap devices from excessive voltage spikes while enabling efficient control signal transmission, thereby enhancing reliability without sacrificing switching performance.
3Strength
If wide bandgap semiconductor devices like SiC are used, then voltage handling capability is improved, but ease of operation deteriorates due to difficulty in interfacing and control
Solution Approach 1:
The patent implements local quality optimization by designing the control interface specifically tailored to the wide bandgap device characteristics. The silicon-based control circuitry is locally optimized with voltage scaling circuits and level shifters that adapt standard low-voltage logic signals to the high-voltage requirements of the wide bandgap power devices, making operation easier while maintaining high voltage handling capability.
Data Source
AI summary
A hybrid silicon carbide (SiC) device includes a first device structure having a first substrate comprising SiC of a first conductivity type and a first SiC layer of the first conductivity type, where the first SiC layer is formed on a face of the first substrate. The first device structure also includes a second SiC layer of a second conductivity type that is formed on a face of the first SiC layer and a first contact region of the first conductivity type, where the first contact region traverses the second SiC layer and contacts the first SiC. The device also includes a second device structure that is bonded to the first device structure. The second device structure includes a switching device formed on a second substrate and a second contact region that traverses a first terminal region of the switching device and contacts the first contact region.