SiC Power Semiconductor Rectification Barrier for Low Freewheel Loss
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Solution Overview
Problem
Conventional silicon carbide power devices have a high conduction voltage drop due to parasitic body diodes, requiring external diodes that are less integrated, more expensive, and less efficient.
Innovation Solution
A power semiconductor device with a contact metal forming a rectification barrier and a source metal wrapping the contact metal, replacing the parasitic body diode, which reduces freewheel conduction voltage drop and enhances reverse recovery speed and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional silicon carbide power device is used with an external freewheel diode, then the device can operate in required applications, but the integration is reduced, cost increases, and efficiency decreases
Solution Approach 1:
The patent combines the freewheel diode function with the power device by introducing a contact metal forming a rectification barrier with the first-conductivity-type doping region. This integration eliminates the need for external diodes, reducing system complexity and improving efficiency while maintaining application compatibility
Solution Approach 2:
The contact metal structure serves multiple functions: it provides electrical contact, forms a rectification barrier to enable freewheel diode functionality, and integrates with the existing power device structure. This multi-functionality allows a single component to replace what previously required separate external diodes
2Ease of operation
If an external diode is used in parallel with the conventional power device, then the freewheel function is achieved, but the conduction voltage drop increases and efficiency decreases
Solution Approach 1:
The patent extracts the rectification function from the external diode and implements it directly within the power device through the contact metal structure. This eliminates the need for current to pass through external diodes with high voltage drops, thereby reducing energy loss while maintaining the freewheel function
Solution Approach 2:
The contact metal acts as an intermediary element that forms a rectification barrier with the doping region, providing the necessary diode functionality internally. This intermediary structure enables low-voltage-drop conduction while maintaining the freewheel capability
3Reliability
If a contact metal forming a rectification barrier is introduced, then the freewheel conduction voltage drop is reduced and reverse recovery speed is improved, but the device structure becomes more complex
Solution Approach 1:
The patent applies local quality by introducing the rectification barrier only at the specific location where the contact metal interfaces with the first-conductivity-type doping region. This localized modification provides the necessary diode functionality and improved reverse recovery performance without requiring complex changes to the entire device structure
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 freewheel conduction voltage drop, increases reverse recovery speed, and lowers reverse recovery peak current compared to conventional power devices, while improving reliability.
Implementation Method 1
a contact metal disposed on the first-conductivity-type doping region and forming a contact barrier having rectification characteristics with the first-conductivity-type doping region below
Data Source
AI summary
A power semiconductor device includes: a substrate; drain metal; a drift region; a base region; a gate structure; a first conductive type doped region contacting the base region on the side of the base region distant from the gate structure; a source region provided in the base region and between the first conductive type doped region and the gate structure; contact metal that is provided on the first conductive type doped region and forms a contact barrier having rectifying characteristics together with the first conductive type doped region below; and source metal wrapping the contact metal and contacting the source region.