RC-IGBT Zones with Lower Emitter Efficiency
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Solution Overview
Problem
Improving the characteristics of multi-mode semiconductor devices like RC-IGBTs often adversely affects another mode of operation, making it challenging to enhance device performance without compromising other functionalities.
Innovation Solution
The semiconductor device design includes a drift zone of a first conductivity type with controllable cells forming a conductive channel, and zones of complementary conductivity types are strategically arranged between the drift zone and a rear side electrode, with a larger third zone having a lower mean emitter efficiency than the second zones, allowing for improved performance in both transistor and reverse conducting modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the characteristics of one mode of multi-mode semiconductor devices are improved, then the device characteristics of that mode are enhanced, but another mode is adversely affected
Solution Approach 1:
The patent applies local quality by creating zones with different doping concentrations and emitter efficiencies in specific regions of the semiconductor device. The third zone has a lower mean emitter efficiency compared to the second zones, allowing different regions to optimize for different operating modes. This spatial variation in properties enables the device to maintain good characteristics in both transistor and reverse conducting modes without mutual interference.
2Power
If the nominal current capacity is increased, then the current handling capability is improved, but the temperature uniformity and charge carrier distribution may deteriorate
Solution Approach 1:
The patent divides the semiconductor structure into zones with different properties (second zones with higher emitter efficiency and a third zone with lower emitter efficiency). This local differentiation allows current to be distributed more evenly across the device structure, preventing concentration in specific areas that would lead to local overheating. The varied zone structure maintains temperature uniformity even at higher current capacities.
Solution Approach 2:
The third zone acts as an intermediary region between the drift zone and the rear side electrode, with its lower mean emitter efficiency serving to moderate and distribute charge carrier flow. This intermediary zone helps achieve a more homogeneous charge carrier plasma distribution, which in turn promotes uniform temperature distribution across the device during high current operation.
3Temperature
If the charge carrier plasma distribution is made more homogeneous, then the temperature uniformity is improved, but the current density distribution may be restricted
Solution Approach 1:
The patent employs local quality through strategically designed zones with different emitter efficiencies. The second zones provide regions of higher current density capability, while the third zone with lower emitter efficiency ensures homogeneous charge carrier plasma distribution. This spatial differentiation allows the device to achieve both uniform temperature and adequate current density distribution simultaneously, as each zone contributes its optimal properties to the overall device performance.
Data Source
AI summary
A semiconductor device includes a drift zone of a first conductivity type in a semiconductor body. Controllable cells are configured to form a conductive channel connected with the drift zone in a first state. First zones of the first conductivity type as well as second zones and a third zone of a complementary second conductivity type are between the drift zone and a rear side electrode, respectively. The first, second and third zones directly adjoin the rear side electrode. The third zone is larger and has a lower mean emitter efficiency than the second zones.