Super Junction Termination Structures for Breakdown Voltage
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Solution Overview
Problem
There is a challenge in designing semiconductor devices with reduced drain-to-source on-resistance (RDS.ON) without compromising breakdown voltage, as modifications to improve breakdown voltage often degrade RDS.ON, and existing techniques like reduced surface field (RESURF) face limitations in achieving an optimal trade-off between these parameters.
Innovation Solution
A semiconductor device with a super junction structure is developed, featuring a termination structure that includes alternating P-type and N-type regions, where the final N-type region is half as wide as the others, and a trench isolation structure formed by polycrystalline material, which helps in maintaining high breakdown voltage and reducing RDS.ON, and can be easily integrated into existing designs without additional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If modifications are made to improve breakdown voltage, then breakdown voltage is improved, but drain-to-source on-resistance (RDS.ON) deteriorates
Solution Approach 1:
The device is divided into multiple cells, each with its own super junction structure and termination region. This segmentation allows the breakdown voltage enhancement to be distributed across multiple localized regions rather than requiring a single large modification that would increase overall resistance. Each cell independently contributes to the breakdown voltage while maintaining low resistance paths for current flow.
Solution Approach 2:
The termination structure implements local quality by creating regions with different doping concentrations and geometries at specific locations. The final N-type region is made narrower than others, and P-type regions are selectively removed in certain areas, creating localized field enhancement regions that improve breakdown voltage without requiring uniform modifications across the entire device that would increase RDS.ON.
2Reliability
If reduced surface field (RESURF) technique is used to improve trade-off between breakdown voltage and RDS.ON, then breakdown voltage is improved, but device structure complexity increases
Solution Approach 1:
The termination structure employs asymmetric geometry where the final N-type region is narrower than the other N-type regions, and P-type regions are selectively removed in specific patterns. This asymmetric design creates controlled field enhancement regions that improve breakdown voltage without requiring the complex symmetric RESURF structures with multiple doped layers and extended termination regions.
Solution Approach 2:
Instead of adding more doped regions and complex structures to enhance breakdown voltage (the conventional RESURF approach), this invention removes P-type regions in specific areas and narrows the final N-type region. This inverted approach—subtracting material rather than adding it—achieves field control and breakdown enhancement with simpler overall device structure.
Data Source
AI summary
A semiconductor device 10 is provided. A first layer 12 has a first dopant type; a second layer 14 is provided over the first layer 12; and a third layer 16 is provided over the second layer and has the first dopant type. A plurality of first and second semiconductor regions 22, 24 are within the third layer. The first semiconductor region 22 has the first dopant type, and the second semiconductor region 24 has the second dopant type. The first and second semiconductor regions 22, 24 are disposed laterally to one another in an alternating pattern to form a super junction, and the super junction terminates with a final second semiconductor region 24, 24′ of the second dopant type.