Superjunction Edge Termination Structure for Higher Breakdown Voltage
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Solution Overview
Problem
The breakdown voltage of state-of-the-art super-junction semiconductor devices is reduced due to charge balance interruption or discontinuity at the edge termination region.
Innovation Solution
A semiconductor power device with an edge termination region that includes electrically floating regions of a first conductivity type over a layer of a second conductivity type, improving charge balance and increasing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional edge termination structures are used in superjunction devices, then the device structure is simple and easy to manufacture, but the breakdown voltage is reduced due to charge balance interruption at the edge termination region
Solution Approach 1:
The edge termination region is segmented into multiple alternating drift regions and partition regions that form vertical p-n junctions. This segmentation allows the charge balance to be maintained at the edge by creating discrete charge compensation zones, thereby improving breakdown voltage without requiring a completely new structure type.
Solution Approach 2:
The patent transitions from a planar edge termination structure to a three-dimensional structure with vertical p-n junctions extending between drift and partition regions. This dimensional change enables charge balance to be achieved in the vertical dimension while maintaining edge termination functionality in the lateral dimension, resolving the breakdown voltage issue.
2Ease of manufacture
If the edge termination region uses simple structure, then manufacturing is easier, but charge balance is interrupted leading to reduced breakdown voltage
Solution Approach 1:
The drift regions and partition regions are formed in advance with specific doping concentrations and geometries that pre-establish the charge balance conditions needed at the edge termination. This preliminary structuring ensures charge balance continuity is achieved without requiring complex post-processing or adjustment steps.
Solution Approach 2:
The patent modifies key parameters including the doping concentrations of drift and partition regions, their geometric dimensions, and their lateral spacing to optimize charge balance at the edge termination. These parameter adjustments maintain manufacturing simplicity while achieving the required electrical performance.
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3~4(a)
AI summary
A semiconductor power device having an active region and an edge termination region surrounding the active region. The device comprises a plurality of drift regions of a first conductivity type and a plurality of partition regions of a second conductivity type alternately in contact with each other, to form a plurality of mutually parallel p-n junctions extending in a vertical direction between adjacent drift regions and partition regions. In the edge termination region, the depths of adjacent drift regions and partition regions decreases through the edge termination region. The device further comprises one or more electrically floating regions of a first conductivity type within the edge termination region.