Superjunction Power Device Pillar Configuration for Breakdown Voltage
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Solution Overview
Problem
Power semiconductor devices, such as MOSFETs and IGBTs, face challenges in achieving optimal performance characteristics like on-resistance, breakdown voltage, and switching speed, particularly in high-voltage applications, where existing technologies struggle to balance these parameters effectively.
Innovation Solution
The development of power devices with active and termination regions featuring alternately arranged pillars of different conductivity types, where the pillars in the termination regions have a higher width than in the active regions, creating a charge balance condition that enhances breakdown voltage without compromising switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breakdown voltage is improved by increasing the drift region thickness, then the on-resistance increases, but the switching speed decreases
Solution Approach 1:
The drift region is segmented into multiple cells with alternating P-type and N-type pillars arranged in a superjunction structure. This segmentation allows the electric field to be distributed across multiple pillars, enabling higher breakdown voltage without proportionally increasing the on-resistance, as each pillar contributes to voltage blocking while maintaining conductive paths
Solution Approach 2:
The patent applies different doping types (P-type and N-type) in alternating pillars within the drift region, creating local charge balance conditions. This local quality variation enables the drift region to simultaneously achieve high breakdown voltage through charge compensation and low on-resistance through maintained carrier concentration in specific regions
2Ease of manufacture
If the on-resistance is reduced by decreasing the drift region thickness, then the breakdown voltage decreases, but the device cannot handle high voltage applications
Solution Approach 1:
The patent changes the electrical parameters within the drift region by introducing alternating P-type and N-type pillars with specific doping concentrations. This parameter change creates a charge balance condition where the net charge is reduced, allowing the drift region to be thinner while maintaining both low on-resistance and high breakdown voltage capabilities
3Reliability
If charge balancing structures are added to the drift region to improve voltage performance, then the device complexity increases, but the manufacturing process becomes more complicated
Solution Approach 1:
The drift region is divided into repeating units of alternating P-type and N-type pillars, creating a modular superjunction structure. This segmentation allows the complex charge balancing function to be achieved through repetitive, standardized patterns that can be manufactured using conventional semiconductor processing techniques, reducing overall manufacturing complexity despite the advanced functionality
Data Source
AI summary
In one general aspect, a power device can include an active region having a plurality of pillars of a first conductivity type alternately arranged with a plurality of pillars of a second conductivity type. The power device can include a termination region surrounding at least a portion of the active region and can have a plurality of pillars of the first conductivity type alternately arranged with a plurality of pillars of the second conductivity type. Each of the plurality of pillars of the first conductivity type in the active region and the termination region can be defined by a trench. The power device can include an enrichment region at a bottom portion of one of the plurality of pillars of the first conductivity type in the active region.