SiC MOSFET With Integrated JBS Diode for Faster Bridge Switching
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Solution Overview
Problem
Silicon carbide MOSFET devices with integrated diodes face issues of high switching times, high voltage drop, and electromagnetic radiation, limiting their performance, and existing solutions are either bulky, costly, or not applicable due to high activation temperatures damaging polysilicon conductive regions.
Innovation Solution
A silicon carbide MOSFET device with a Junction-Barrier Schottky (JBS) diode integrated in parallel, formed by implanting P-type doping species and creating isolated gate structures, allowing for reduced dimensions and efficient operation without damaging the polysilicon regions at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a body-drain diode is integrated in a silicon carbide MOSFET device, then the device can operate in bridge configurations, but the diode exhibits high switching times, high voltage drop, and electromagnetic radiation
Solution Approach 1:
The diode function is segmented from the MOSFET structure by introducing a separate JBS diode with its own independent P-type body region and metallization contacts. This allows the diode to operate independently with optimized characteristics, separating the switching function from the MOSFET channel and reducing electromagnetic interference while maintaining bridge configuration capability
Solution Approach 2:
The patent employs a composite structure combining MOSFET and JBS diode regions within the same silicon carbide body. The JBS diode utilizes a hybrid junction of P-type semiconductor region and metal contact, creating a composite material system that achieves lower voltage drop and faster switching compared to traditional body-drain diodes
2Volume of moving object
If a Schottky diode is integrated with a MOS transistor in one and the same body of silicon carbide, then the dimensions are reduced, but the high activation temperatures damage the polysilicon conductive region
Solution Approach 1:
The JBS diode structure is formed with P-type doping in the body region before the isolated gate and polysilicon conductive regions are created. This preliminary formation of the diode structure allows subsequent low-temperature polysilicon deposition without requiring high-temperature Schottky contact formation, thus preserving the polysilicon regions while achieving integrated diode functionality
Solution Approach 2:
The patent changes the manufacturing parameters by using P-type doping and JBS diode formation instead of traditional Schottky contact formation. This parameter change allows the diode to be formed at lower temperatures compatible with polysilicon processing, enabling integrated diode-MOSFET structures without damaging the conductive regions
3Reliability
If a JBS diode is formed by implanting P-type doping species in the JFET region, then the ignition voltage is reduced and efficiency is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The P-type doping implantation in the JFET region serves multiple functions simultaneously: it creates the JBS diode structure for low-voltage operation, forms the body region for the MOSFET, and establishes the necessary electrical characteristics for both diode and transistor operation. This multi-functionality reduces manufacturing complexity despite the enhanced performance
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 solution reduces ignition voltage, enhances efficiency, and lowers manufacturing costs by integrating the JBS diode within the MOSFET device, offering improved performance and cost-effectiveness in bridge configurations.
Implementation Method 1
an implanted structure, with the second type of conductivity, extending into the JFET region from the first surface; and a first metallization layer extending over the first surface, the first metallization layer being in direct contact with the implanted structure and with the JFET region and forming a Junction-Barrier Schottky (JBS) diode
Data Source
AI summary
An integrated MOSFET device is formed in a body of silicon carbide and with a first type of conductivity. The body accommodates a first body region, with a second type of conductivity; a JFET region adjacent to the first body region; a first source region, with the first type of conductivity, extending into the interior of the first body region; an implanted structure, with the second type of conductivity, extending into the interior of the JFET region. An isolated gate structure lies partially over the first body region, the first source region and the JFET region. A first metallization layer extends over the first surface and forms, in direct contact with the implanted structure and with the JFET region, a JBS diode.