Super Junction Strip Structures for Edge Area Breakdown Voltage
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Solution Overview
Problem
Super junction semiconductor devices face challenges in improving reliability, particularly in accommodating high reverse breakdown voltage at high impurity concentrations, which affects their performance and longevity.
Innovation Solution
The introduction of strip structures with compensation layers of inverse conductivity types extending into the edge area, including end sections and varying configurations, enhances the breakdown voltage and ruggedness by modulating the electric field distribution and impurity loading, thereby improving the device's reliability and avalanche resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the impurity concentration in the doped layer is increased to accommodate high reverse breakdown voltage, then the reverse blocking capability is improved, but the device reliability deteriorates due to reduced avalanche ruggedness and increased susceptibility to destructive current filaments
Solution Approach 1:
The patent introduces strip structures with alternating first and second compensation layers of different conductivity types at specific locations in the edge area. These localized compensation structures create non-uniform impurity distribution, where the edge regions with strip structures provide enhanced avalanche ruggedness while the cell area maintains high impurity concentration for reverse blocking. This local quality modification allows the device to achieve both high reverse breakdown voltage and improved avalanche resistance.
2Strength
If the device operates in reverse blocking mode with high impurity concentration, then the reverse breakdown voltage is maintained, but the electric field distribution becomes concentrated, leading to premature breakdown and reduced device longevity
Solution Approach 1:
The strip structures with alternating compensation layers act as intermediary elements in the edge area. These structures modify the electric field distribution by introducing controlled impurity variations that spread and redistribute the electric field lines. The compensation layers serve as mediators that prevent electric field concentration at the edges, thereby maintaining uniform electric field distribution across the device while preserving high reverse breakdown voltage capability.
3Strength
If conventional trench-based super junction structure is used, then the device achieves good reverse blocking performance, but the edge area lacks sufficient protection against avalanche breakdown and current filament formation
Solution Approach 1:
The patent segments the edge area protection by introducing discrete strip structures with alternating compensation layers at specific positions. Instead of uniform doping throughout, the edge region is divided into segments with different compensation characteristics. This segmentation allows targeted protection against avalanche breakdown in the edge area while maintaining the reverse blocking performance in the cell area, effectively addressing the harmful factors without compromising overall device performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively increases the nominal breakdown voltage in the edge area, reducing the occurrence of destructive current filaments and enhancing avalanche ruggedness, ensuring improved reliability and performance of the super junction semiconductor devices.
Implementation Method 1
enhances the breakdown voltage and ruggedness by modulating the electric field distribution
Implementation Method 2
Each strip structure includes a compensation structure with a first and a second section inversely provided on opposing sides of a fill structure. Each section includes a first compensation layer of a first conductivity type and a second compensation layer of a complementary second conductivity type.
Implementation Method 3
In a reverse blocking mode the complementary doped layer pair is depleted such that the device can accommodate a high reverse breakdown voltage
Implementation Method 4
enhancing avalanche ruggedness, ensuring improved reliability
Data Source
AI summary
A super junction semiconductor device includes a semiconductor portion having strip structures in a cell area. Each strip structure has a compensation structure with first and second sections inversely provided on opposite sides of a fill structure. Each section has first and second compensation layers of complementary conductivity types. The strip structures are linear stripes extending through the cell area in a first lateral direction and into an edge area surrounding the cell area in lateral directions. Each strip structure has an end section with a termination portion in the edge area in which the first compensation layer of the first section is connected with the first compensation layer of the second section via a first conductivity layer, and the second compensation layer of the first section is connected with the second compensation layer of the second section via a second conductivity layer.