Superjunction PN Layer Transition for Breakdown Voltage Stability
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Solution Overview
Problem
Conventional vertical semiconductor devices with a super junction (SJ) structure face issues with charge imbalance at the boundary between the active region and the edge termination region, leading to local electric field concentration and decreased breakdown voltage due to process variations.
Innovation Solution
A semiconductor device with a parallel pn layer structure, where the doping concentration of the n-type and p-type column regions is high in the active region, progressively decreases in the transition region, and is low in the edge termination region, thereby maintaining balanced charge across the regions and suppressing electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration of column regions is reduced in the edge termination region to increase breakdown voltage, then the breakdown voltage of the edge termination region increases, but charge imbalance occurs at the boundary between active region and edge termination region, leading to local electric field concentration and decreased reliability
Solution Approach 1:
The patent applies local quality by implementing different doping concentration profiles in different regions: the active region maintains high doping concentration for low on-resistance, while the edge termination region uses low doping concentration for high breakdown voltage. The transition region serves as an intermediate zone with graded doping concentration to smoothly connect these two extremes, preventing charge imbalance and electric field concentration at the boundary.
Solution Approach 2:
The patent utilizes parameter changes by progressively varying the doping concentration from the active region through the transition region to the edge termination region. This continuous parameter transition ensures that charge distribution remains balanced across regions while maintaining high breakdown voltage in the edge termination area, eliminating the harmful effect of local electric field concentration.
2Reliability
If a transition region is introduced between the active region and edge termination region to prevent charge imbalance, then electric field concentration is suppressed, but the device structure becomes more complex
Solution Approach 1:
The patent merges the transition region with the existing active region and edge termination region into a unified continuous structure. Rather than creating separate discrete regions, the doping concentration profile continuously transitions across all three zones, effectively combining them into one integrated structure that prevents charge imbalance without adding significant structural complexity.
Data Source
AI summary
The semiconductor substrate has an active region, a termination regions surrounding a periphery of the active region, and a transition region between the active region and the termination region. The transition region has a portion that overlaps an outer peripheral portion of the active region by a predetermined width. The portion of the transition region includes at least one pair of one of the n-type column regions in the active region and an adjacent one of the p-type column regions in the active region. The parallel pn layer exhibits doping concentration distributions of n-type and p-type in each of which the doping concentration is relatively high in a center portion of the active region, progressively decreases in the transition region in a direction from the active region to the edge termination region, and is relatively high in the termination region.