SiC MOSFET With Integrated JBS Diode for Lower Switching Loss
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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 such as parallel diodes are bulky and costly, making them unsuitable for all applications.
Innovation Solution
The integration of a Junction-Barrier Schottky (JBS) diode within the MOSFET device, formed by implanting P-type regions and forming a metallization layer in contact with the JFET region, allowing for reduced dimensions and efficient operation without damaging polysilicon structures at high activation temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a body-drain diode is formed in a conventional 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 patent merges the MOSFET transistor and diode into a single integrated device structure. The diode is formed by utilizing the body-drain junction of the MOSFET itself, eliminating the need for a separate parallel diode component. This integration reduces the overall device footprint and eliminates the harmful effects associated with discrete diode implementations while maintaining the ability to operate in bridge configurations.
2Reliability
If a parallel diode is added to improve MOSFET performance in bridge configurations, then switching performance improves, but the device becomes bulky and costly
Solution Approach 1:
The patent combines the MOSFET and diode functions into a single integrated device, eliminating the need for separate parallel components. The diode is formed by the body-drain junction of the MOSFET, reducing device complexity and cost while maintaining improved switching performance through the integrated structure.
3Ease of manufacture
If high activation temperatures are used to form the diode, then the diode structure is created, but polysilicon structures are damaged
Solution Approach 1:
The patent performs the diode formation process before the polysilicon gate deposition. By creating the diode structure first through ion implantation and thermal processing, and then depositing the polysilicon gate layer subsequently, the polysilicon structures are protected from damage during high-temperature activation processes. This sequence ensures both diode formation and polysilicon integrity.
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 JBS diode reduces ignition voltage, enhances efficiency, and lowers manufacturing costs by integrating the diode within the MOSFET device, offering improved performance and cost-effectiveness compared to discrete solutions.
Implementation Method 1
forming a first metallization layer on the first surface in direct contact with the implanted structure and with the JFET region and forming a Junction-Barrier Schottky (JBS) diode that includes the implanted structure and the JFET region
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.