Semiconductor Device Reverse Recovery Tolerance
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Solution Overview
Problem
Existing power semiconductor modules face challenges in preventing electric current concentration at the boundary between the edge termination structure and active part, leading to breakdown issues during reverse recovery, due to inappropriate resistance values in the resistance region.
Innovation Solution
A semiconductor device is designed with a resistance region between the p-anode and p-guard ring regions, along with a low-density p-diffusion region in contact with the p-anode, and a high-density region in the surface layer to suppress electric current concentration. This includes a deeper diffusion depth for the resistance region and shallower diffusion depth for the p-guard ring regions, with the p-anode region receding inward from the anode electrode to alleviate electric current concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resistance value in the resistance region is not appropriately set, then the manufacturing is simpler, but electric current concentration occurs at the boundary between edge termination structure and active part causing breakdown
Solution Approach 1:
The patent applies local quality by creating distinct regions with different impurity densities (high-density and low-density p-diffusion regions) and different diffusion depths within the resistance region. This local differentiation allows the structure to simultaneously achieve current concentration suppression at boundaries while maintaining appropriate resistance values, thereby improving reverse recovery tolerance without excessive complexity
Solution Approach 2:
The resistance region is segmented into multiple diffusion regions with different characteristics (high-density region with deeper diffusion depth, low-density region with shallower diffusion depth). This segmentation enables each sub-region to perform specific functions: the high-density region suppresses current concentration at the active part boundary, while the low-density region controls the overall resistance value, achieving reliable reverse recovery performance
2Reliability
If the resistance region has appropriate resistance value, then electric current concentration is suppressed, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes parameter changes by varying impurity density and diffusion depth across different regions within the resistance region. The high-density region has deeper diffusion depth while the low-density region has shallower diffusion depth. These parameter variations are achieved through controlled thermal diffusion processes, allowing precise control of electrical characteristics while using standard semiconductor manufacturing techniques
Solution Approach 2:
The resistance region is formed preliminarily during the manufacturing process by controlling the diffusion depth and impurity concentration before final device assembly. The high-density and low-density regions are created in advance with specific diffusion depths, pre-establishing the electrical characteristics needed to suppress current concentration and prevent breakdown during operation
Data Source
AI summary
The semiconductor device includes a p-anode region disposed on an n-drift region, and a p-diffusion region disposed so as to be in contact with the p-anode region on the n-drift region. A resistance region disposed so as to be in contact with the p-diffusion region on an n− region, a plurality of p-guard ring regions, and a stopper region disposed away from the p-guard ring regions are provided. By providing the p-diffusion region, withdrawal of holes that concentrate to the p-anode region at the time of reverse recovery is suppressed, so that the semiconductor device has a high reverse recovery tolerance.