Superjunction Transistor Edge Doping for Avalanche Breakdown Control
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Solution Overview
Problem
Existing superjunction transistor devices face challenges in achieving higher voltage blocking capability in the edge region compared to the inner region, leading to potential Avalanche breakdown in the inner region with a larger area and volume.
Innovation Solution
A method is developed to form first and second doping type regions in the edge region with lower lateral doping doses by adjusting the diffusion rate and length of dopant atoms, using a protection layer to control interstitial injection and promote differential diffusion in the edge and inner regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration in the edge region is increased to improve voltage blocking capability, then the voltage blocking capability is improved, but the Avalanche breakdown risk in the inner region increases
Solution Approach 1:
The patent applies local quality by creating different doping concentrations in different regions of the semiconductor device. The edge region has a higher doping concentration than the inner region, allowing the edge region to provide enhanced voltage blocking capability while the inner region maintains lower doping to prevent Avalanche breakdown. This spatial variation in doping concentration resolves the contradiction by optimizing each region for its specific function.
2Ease of manufacture
If the doping concentration is uniform across the device, then the manufacturing process is simplified, but the voltage blocking capability in the edge region is insufficient
Solution Approach 1:
The patent segments the doping process into two distinct steps: a first doping step that uniformly dopes the entire semiconductor structure, and a second doping step that selectively increases doping concentration only in the edge region. This segmentation allows the manufacturing process to remain relatively simple while achieving the required non-uniform doping profile for enhanced voltage blocking capability in the edge region.
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 approach enhances the voltage blocking capability in the edge region, ensuring Avalanche breakdown occurs in the edge region with a higher area and volume, providing improved robustness and reliability.
Implementation Method 1
adjusting the diffusion rate and length of dopant atoms, using a protection layer to control interstitial injection and promote differential diffusion in the edge and inner regions
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
A method for forming a transistor device and a transistor device are disclosed. The method includes: forming a plurality of first regions of a first doping type and a plurality of second regions of a second doping type in an inner region and an edge region of a semiconductor body; and forming body regions and source regions of a plurality of transistor cells in the inner region of the semiconductor body. Forming the first regions and the second regions includes: forming a plurality of first implanted regions and a plurality of second implanted regions in the inner region and the edge region of the semiconductor body, wherein each of the first implanted regions includes at least dopant atoms of a first doping type, and wherein each of the second implanted regions includes at least dopant atoms of a second doping type; and diffusing the dopant atoms of the first doping type and the second doping type in a thermal process such that dopant atoms of at least one of the first doping type and the second doping type have at least one of different diffusion rates and diffusion lengths in the inner region and the edge region.