SiC Semiconductor Device with Segmented Non-Operating Region
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Solution Overview
Problem
Conventional semiconductor devices with silicon carbide (SiC) 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 wider bandgap material like silicon carbide with a specific layout where the n-type region surrounds the sensing effective region in the non-operating area, reducing the p-type base region and enhancing the breakdown voltage, thereby mitigating the reverse recovery current and increasing the reverse recovery capability of the parasitic diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the non-operating region has a large surface area to accommodate circuit portions, then the device can integrate more functional elements, but the reverse recovery current increases and the current sensing portion becomes susceptible to destruction
Solution Approach 1:
The non-operating region is divided into multiple isolated n-type regions (n-type first region, n-type second region, n-type third region) that are electrically separated from each other. This segmentation prevents hole current from flowing across the entire non-operating region, thereby reducing reverse recovery current while still providing sufficient area for integrating circuit portions such as current sensing elements, temperature sensing elements, and control circuits.
Solution Approach 2:
Different regions within the non-operating area are assigned different n-type regions with specific local functions. The n-type first region is positioned to isolate the current sensing portion, the n-type second region isolates the temperature sensing element, and the n-type third region isolates the control circuit. This localized quality assignment optimizes the reverse recovery performance in each specific area while maintaining overall device functionality.
2Speed
If silicon carbide material is used to achieve high-speed and high-current characteristics, then the switching speed and current capacity improve, but the reverse recovery current still becomes excessive in devices with large non-operating regions
Solution Approach 1:
The n-type regions are segmented into multiple isolated zones within the non-operating region, preventing the formation of continuous hole current paths. This segmentation maintains the high-speed switching characteristics of silicon carbide while dramatically reducing the reverse recovery current that would otherwise flow through the large non-operating region.
3Reliability
If the p-type base region is reduced to lower reverse recovery current, then the reverse recovery capability improves, but the breakdown voltage may be affected
Solution Approach 1:
n-type regions are strategically positioned at critical locations within the non-operating region to provide localized electric field termination and hole current blocking. This local quality enhancement allows the p-type base region to be reduced overall while maintaining adequate breakdown voltage through the distributed n-type region structure.
Solution Approach 2:
The n-type regions act as intermediary structures between the p-type base region and the drift region, providing a transition zone that manages both the reverse recovery current and the electric field distribution. These intermediary n-type regions enable the device to achieve low reverse recovery current while maintaining sufficient breakdown voltage through their strategic positioning and doping characteristics.
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
This design effectively reduces the reverse recovery current and enhances the reverse recovery capability of the parasitic diode, improving the reliability and efficiency of the current sensing portion by minimizing the flow of hole current into the sensing effective region.
Implementation Method 1
a built-in parasitic diode formed by a pn junction between a p-type base region and an n−-type drift region
Implementation Method 2
increased reverse recovery current and susceptibility to destruction in the current sensing portion
Data Source
AI summary
Unit cells of a current sensing portion are disposed in a sensing effective region of a main non-operating region. In a sensing non-operating region of the main non-operating region excluding the sensing effective region, an n−-type region that surrounds a periphery of the sensing effective region is disposed in a surface region of the front surface of the semiconductor substrate. In the main non-operating region, a p-type base region disposed in a surface region of the front surface of the semiconductor substrate opposes the sensing effective region across the n−-type region. The p-type base region is fixed at a source potential of the main semiconductor element 11. A field insulating film on the front surface of the semiconductor substrate is thicker at a portion that covers the n−-type region that in other portions.