SiC Semiconductor Floating Base Region Reverse Recovery
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Solution Overview
Problem
Conventional semiconductor devices with silicon carbide (SiC) materials face challenges in high-speed and high-current applications due to the large surface area of the non-operating region, which leads to increased reverse recovery current and susceptibility to destruction in the current sensing portion.
Innovation Solution
The semiconductor device design includes a floating p-type base region in the non-operating region to reduce the surface area and electric field concentration, enhancing the breakdown voltage and reverse recovery capability by separating the parasitic diode formation from the current sensing portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the non-operating region is made large to accommodate circuit portions for protecting/controlling the main semiconductor element, then the device functionality is improved, but the reverse recovery current increases and the current sensing portion becomes susceptible to destruction
Solution Approach 1:
The non-operating region is segmented into a first non-operating region and a second non-operating region that are electrically isolated from each other. The first non-operating region contains circuit portions for protecting/controlling the main semiconductor element, while the second non-operating region contains the current sensing portion. This segmentation prevents reverse recovery current generated in the first region from affecting the current sensing portion in the second region.
Solution Approach 2:
The current sensing portion is extracted from the first non-operating region and placed in a separate second non-operating region that is electrically isolated. This extraction removes the current sensing portion from the harmful electrical environment of the first non-operating region, protecting it from reverse recovery current while maintaining its sensing function.
2Speed
If silicon carbide material is used to achieve high-speed and high-current characteristics, then the switching speed and current capacity are improved, but the reverse recovery current in the non-operating region increases
Solution Approach 1:
The non-operating region is divided into electrically isolated first and second non-operating regions. This segmentation isolates the current sensing portion in the second region from the reverse recovery current generated in the first region, allowing silicon carbide to maintain its high-speed switching capability while preventing reverse recovery current from affecting the sensing portion.
Data Source
AI summary
A region of a portion directly beneath an OC pad is a sensing effective region where unit cells of a current sensing portion are disposed. Directly beneath the OC pad, a region surrounding a periphery of the sensing effective region is a sensing non-operating region in which no unit cells of the current sensing portion are disposed. In the sensing non-operating region, a first p-type base region that floats is provided in a surface region of the front surface of the semiconductor substrate and is separated from a second p-type base region of the sensing effective region by an n−-type region that surrounds a periphery of the sensing effective region. The n−-type region has a surface area that is greater than that of the sensing effective region. A distance between the first and the second p-type base regions is at least 0.1 μm and is as small as possible.