Super Junction Semiconductor Structure for Breakdown Voltage Stability
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Solution Overview
Problem
Conventional semiconductor devices with a super junction structure experience a reduction in breakdown voltage due to electric field concentration at the edge of p-type column regions opposed to n-type electrode-connection regions with high impurity concentration during reverse bias.
Innovation Solution
Incorporating a low-density electric-field relaxation region between the column region and the second electrode-connection region, which has a lower impurity concentration than the drift region, to relax the electric field concentration and maintain a uniform electric field distribution, thereby preventing a decrease in breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a super junction structure with high impurity concentration electrode-connection regions is used, then ON resistance is reduced, but breakdown voltage decreases due to electric field concentration at column region edges
Solution Approach 1:
A low-density electric-field relaxation region is introduced as an intermediary between the column region and the electrode-connection region. This relaxation region has lower impurity concentration than the drift region, which reduces electric field concentration at the column region edges while maintaining the beneficial low ON resistance properties of the high impurity concentration electrode-connection regions.
Solution Approach 2:
The patent applies local quality by creating a region with specifically tailored impurity concentration characteristics. The low-density electric-field relaxation region has a different impurity concentration profile compared to both the drift region and the electrode-connection region, allowing localized control of electric field distribution to prevent breakdown voltage reduction.
2Ease of manufacture
If uniform impurity concentration is maintained in the drift region, then manufacturing is simplified, but electric field uniformity deteriorates at column region boundaries
Solution Approach 1:
The drift region is segmented into multiple zones with different impurity concentration characteristics: the main drift region with higher impurity concentration for low ON resistance, and the low-density electric-field relaxation region with lower impurity concentration for electric field uniformity. This segmentation allows each zone to perform its specific function optimally.
Solution Approach 2:
By creating a localized region with different impurity concentration properties (the low-density relaxation region), the patent achieves non-uniform impurity distribution only where needed for electric field control, while maintaining simpler manufacturing conditions in the majority of the drift region.
Data Source
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AI summary
A semiconductor device includes a semiconductor base body (20), and a first main electrode (30) and a second main electrode (40) provided on the semiconductor base body (20). The semiconductor base body (20) includes a drift region (21) of a first conductivity type through which a main current flows, a column region (22) of a second conductivity type arranged adjacent to the drift region (21) in parallel to a current passage of the main current, a second electrode-connection region (24) of the first conductivity type electrically connected to the second main electrode (40), and a low-density electric-field relaxation region (25) of the first conductivity type having a lower impurity concentration than the drift region (21) and arranged between the second electrode-connection region (24) and the column region (22).