Bipolar Semiconductor Diode with Segmented Anode for Soft Recovery
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Solution Overview
Problem
Existing semiconductor diodes face challenges in achieving both soft recovery behavior and high surge current strength, with previous solutions like the SPEED concept and emitter switched diodes either lacking robustness or requiring complex manufacturing and active control.
Innovation Solution
A bipolar semiconductor component with a semiconductor body featuring p-doped anode emitter zones spaced by n-doped channel zones, and a cathode structure with n-doped buffer regions and p-doped island zones, allowing current paths only through n-doped zones for controlled emitter efficiency and enhanced surge current handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plasma concentration is reduced on the anode side to achieve soft recovery behavior, then the soft recovery behavior is improved, but the anodal emitter efficiency is reduced and surge current strength is impaired
Solution Approach 1:
The anode emitter zone is divided into multiple p-doped zones spaced apart by n-doped channel zones. This segmentation allows different regions to serve different functions: the p-doped zones provide high emitter efficiency for surge current handling, while the n-doped channel zones maintain low plasma concentration for soft recovery behavior.
Solution Approach 2:
Different doping concentrations and types are applied in different spatial regions. The p-doped anode emitter zones have high doping concentration for high emitter efficiency, while the n-doped channel zones have appropriate doping to maintain low plasma concentration. This local differentiation resolves the contradiction between soft recovery and surge current strength.
2Strength
If the p+-type zones are heavily doped to improve surge current strength, then the surge current strength is improved, but the reverse recovery behavior deteriorates
Solution Approach 1:
The anode emitter structure is segmented into discrete p-doped zones separated by n-doped channel zones. This segmentation prevents the formation of large plasma regions that cause hard recovery, while still providing sufficient injection capability for surge current handling through the distributed p-doped zones.
Solution Approach 2:
The doping concentration and distribution are optimized to achieve the right balance. The p-doped zones are heavily doped for high emitter efficiency, but their spatial separation by n-doped channels limits the total plasma concentration, thereby maintaining good reverse recovery behavior.
3Reliability
If the p+-type zones are lightly doped or have small horizontal area to maintain soft recovery behavior, then the soft recovery behavior is maintained, but the improvement in surge current strength is only moderate
Solution Approach 1:
Multiple p-doped zones are distributed across the anode surface, each with moderate dimensions. The cumulative effect of multiple zones provides high surge current strength, while the n-doped channel zones between them maintain low plasma concentration for soft recovery behavior.
Solution Approach 2:
Each p-doped zone is designed with appropriate local doping concentration and area to provide high emitter efficiency, while the n-doped channel zones locally maintain low plasma concentration. The combination achieves both high surge current strength and soft recovery behavior.
4Reliability
If additional structures like MOS channels or control electrodes are added to achieve both soft recovery and high surge current strength, then the performance is improved, but the manufacturing complexity and device control complexity increase
Solution Approach 1:
The diode structure itself provides the necessary functionality through its doping profile without requiring external control. The n-doped channel zones and p-doped emitter zones automatically create the desired plasma distribution and emitter efficiency characteristics, eliminating the need for additional control electrodes or MOS channels.
Solution Approach 2:
The complex control mechanisms (MOS channels, control electrodes) are removed entirely. Instead, the desired functionality is achieved through a simplified doping structure that inherently provides both soft recovery behavior and high surge current strength without external intervention.
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
The solution enables a semiconductor diode with both high overcurrent robustness and soft recovery behavior, avoiding the limitations of previous designs by maintaining low emitter efficiency at low current densities and high efficiency at high densities without external control, thus improving switching performance.
Implementation Method 1
p-doped anode emitter zones spaced by n-doped channel zones
Implementation Method 2
at least one current path runs in the semiconductor body only through n-doped zones
Implementation Method 3
load pn junction
Implementation Method 4
bipolar semiconductor component with a fully depletable channel zone
Data Source
AI summary
A bipolar semiconductor component includes a semiconductor body having first and second substantially parallel main surfaces and at least one load pn junction, a first metallization on the first surface, a second metallization on the second surface, and a current path running in the semiconductor body from the first metallization to the second metallization only through n-doped zones, including between first and second p-doped zones which are in contact with the first metallization and spaced apart from one another by an n-doped channel zone through which the current path runs. A space charge region forms in the semiconductor body between the first and second p-doped zones to fully deplete the n-doped channel zone between the first and second p-doped zones and therefore prevent current flow between the first and second metallizations along the current path when a positive voltage is applied between the second metallization and the first metallization.