Power Superjunction MOSFET Resurf Regions for Breakdown Voltage
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Solution Overview
Problem
In semiconductor devices, particularly power MOSFETs with super junction structures, achieving high breakdown voltage with low on-resistance is challenging, especially in peripheral regions where the conventional junction edge termination and resurf structures fail to maintain the same breakdown voltage as the cell region.
Innovation Solution
A semiconductor device with a super junction structure in the drift region around the cell region, oriented parallel to the cell region's sides, is implemented using the trench fill technique, which includes multiple super junction structures with specific orientations and configurations to enhance breakdown voltage and reduce on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional junction edge termination structure or resurf structure is used in peripheral regions, then manufacturing is simpler, but breakdown voltage drops in peripheral areas compared to cell region
Solution Approach 1:
The patent applies different structures to different regions: the cell region uses conventional super junction structure while peripheral regions use extended P-type drift regions with specific doping concentrations. This local differentiation allows each region to be optimized for its specific function, maintaining high breakdown voltage in peripheral areas without complicating the overall device structure.
Solution Approach 2:
The patent changes the doping concentration parameters in peripheral regions by extending P-type drift regions with lower doping concentrations compared to the cell region. This parameter modification enables the peripheral regions to achieve equivalent or higher breakdown voltages while maintaining compatibility with the existing super junction structure.
2Adaptability or versatility
If multi-epitaxial technique is used to introduce super junction structure, then design flexibility is improved, but manufacturing cost increases due to complicated process
Solution Approach 1:
The patent segments the device into cell regions and peripheral regions, allowing different structures and processes to be applied to each. The peripheral regions use extended P-type drift regions that can be formed using standard ion implantation and thermal diffusion processes, avoiding the need for complex multi-epitaxial growth while maintaining design flexibility through parameter optimization.
3Device complexity
If trench insulating film filling technique is used, then process complexity is reduced, but device area increases due to trench requirements
Solution Approach 1:
The patent extracts the insulating film filling step from the process, using only ion implantation and thermal diffusion to form the extended P-type drift regions in peripheral areas. This eliminates the need for trench formation and insulating film deposition, significantly reducing the device area while maintaining process simplicity.
Data Source
AI summary
A semiconductor device which solves the following problem of a super junction structure: due to a relatively high concentration in the body cell region (active region), in peripheral areas (peripheral regions or junction end regions), it is difficult to achieve a breakdown voltage equivalent to or higher than in the cell region through a conventional junction edge terminal structure or resurf structure. The semiconductor device includes a power MOSFET having a super junction structure formed in the cell region by a trench fill technique. Also, super junction structures having orientations parallel to the sides of the cell region are provided in a drift region around the cell region.