SiC Trench Transistor Superjunction Design for Bipolar Degradation
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Solution Overview
Problem
Silicon Carbide (SiC) semiconductor devices suffer from bipolar degradation due to crystal defects, leading to increased on-resistance and leakage current, and require improved Avalanche robustness in power electronics applications.
Innovation Solution
A trench structure is formed in the SiC semiconductor body with mesa regions and compensation regions, where dopant atoms are implanted via sidewalls to create a superjunction structure, reducing defect propagation and enhancing voltage blocking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a SiC semiconductor body is used for high voltage blocking capabilities, then low switching losses are achieved, but bipolar degradation occurs due to crystal defects
Solution Approach 1:
The semiconductor body is divided into multiple regions with different doping types (first doping type and second doping type) arranged in an alternating pattern. This segmentation creates a superjunction structure that prevents the propagation of crystal defects while maintaining high voltage blocking capabilities and reducing switching losses.
Solution Approach 2:
Different regions of the semiconductor body are assigned different doping types and concentrations locally. The alternating pattern of first and second doping types creates localized compensation regions that counteract the effects of crystal defects at specific locations, preventing bipolar degradation while preserving overall device performance.
2Reliability
If crystal defects are present in the SiC semiconductor body, then bipolar degradation increases, but device properties such as on-resistance and leakage current are degraded
Solution Approach 1:
The doping concentration and type are varied spatially to create a superjunction structure with alternating regions. By changing the doping parameters (type and concentration) in an alternating pattern, the device achieves high resistance to bipolar degradation while maintaining low on-resistance and leakage current through compensating electric fields.
3Reliability
If a trench structure with mesa regions is formed, then defect propagation is reduced, but device complexity increases
Solution Approach 1:
The trench structure divides the semiconductor body into discrete mesa regions separated by trenches filled with material of a different doping type. This segmentation physically isolates crystal defects within individual mesas, preventing their propagation to adjacent regions, while the systematic alternating doping pattern maintains manufacturing feasibility.
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 effectively reduces bipolar degradation and increases Avalanche robustness, improving the performance and reliability of SiC-based transistor devices by minimizing defect expansion and enhancing high-voltage blocking capabilities.
Implementation Method 1
forming the at least one compensation region includes implanting dopant atoms of a second doping type via sidewalls of the trenches into the mesa regions in the inner region
Data Source
Figure 1~2
Figure 3~6
Figure 7A~7C
AI summary
A method for forming a semiconductor device and a semiconductor device are disclosed. The method includes: forming a trench structure (2) with a plurality of trenches (22) in an inner region (130) and an edge region (140) of a SiC semiconductor body (100) such that the trench structure (2) extends from a first surface (101) of the semiconductor body (100) through a second semiconductor layer (120) into a first semiconductor layer (110) and such that the trench structure (2), in the second semiconductor layer (120), into forms a plurality of mesa regions; and forming at least one transistor cell (1) at least partially in each of the mesa regions (121) in the inner region (130). Forming each transistor cell (1) includes forming at least one compensation region (17), forming the at least one compensation region (17) includes implanting dopant atoms of a second doping type via sidewalls of the trenches (22) into the mesa regions (121) in the inner region (130), and forming the at least one compensation region (17) in each of the mesa regions (121) in the inner region (121) includes at least partially covering the edge region (140) with an implantation mask (301; 401).