Semiconductor Superjunction Drift Region Voltage Blocking Optimization
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Solution Overview
Problem
Current power integrated circuits face a trade-off between voltage blocking capability and specific on-resistance, leading to increased leakage current and degraded performance at high voltages, with existing RESURF structures failing to optimize the size reduction of power devices effectively.
Innovation Solution
The introduction of buried superjunction layers and deep N-drift extensions in the semiconductor device allows current to spread deeper into the drift region, improving the breakdown voltage and on-resistance trade-off without degrading voltage blocking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentration of dopants is used in the various regions of the device, then the operational on-resistance is reduced, but the voltage blocking performance is degraded due to enhanced electric field near heavily doped junctions causing increased leakage current
Solution Approach 1:
The drift region is segmented into multiple alternating P-type and N-type superjunction columns. This segmentation distributes the voltage blocking function across multiple junctions, reducing the electric field concentration at any single junction while maintaining low on-resistance through the parallel conduction paths.
Solution Approach 2:
Different regions of the device are given different doping types and concentrations optimized for their specific functions: the superjunction columns have alternating doping types for voltage blocking, while the drift region provides the conduction path. Each region's properties are locally optimized rather than uniform throughout.
2Reliability
If modifications are made in the device structure to improve voltage blocking performance, then the voltage blocking capability is enhanced, but the operational on-resistance is degraded
Solution Approach 1:
The drift region is divided into multiple alternating P-type and N-type superjunction columns. This segmentation allows voltage blocking to be distributed across many small junctions rather than one large junction, reducing electric field concentration while providing multiple parallel conduction paths to maintain low on-resistance.
Solution Approach 2:
The device uses a composite structure with alternating P-type and N-type doped regions within the drift zone. This composite superjunction structure combines the voltage blocking capability of reverse-biased junctions with the low resistance of closely spaced opposite-type regions, achieving both high breakdown voltage and low on-resistance simultaneously.
Data Source
AI summary
A semiconductor device may include a semiconductor substrate having a first dopant type. A first semiconductor region within the semiconductor substrate may have a plurality of first and second portions (44, 54). The first portions (44) may have a first thickness, and the second portions (54) may have a second thickness. The first semiconductor region may have a second dopant type. A plurality of second semiconductor regions (42) within the semiconductor substrate may each be positioned at least one of directly below and directly above a respective one of the first portions (44) of the first semiconductor region and laterally between a respective pair of the second portions (54) of the first semiconductor region. A third semiconductor region (56) within the semiconductor substrate may have the first dopant type. A gate electrode (64) may be over at least a portion of the first semiconductor region and at least a portion of the third semiconductor region (56).