Decoupled Trigger Thyristor for Reverse Recovery Protection
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Solution Overview
Problem
Thyristors are vulnerable to destruction during steep voltage rises in the forward direction during the reverse recovery time due to a positive electric potential at the cathode compared to the anode.
Innovation Solution
The thyristor design features a second contact surface of the n-doped firing stage emitter spaced from the p-doped base, increasing the net dopant concentration in the p-doped base area, enhancing the amplification factor and residual plasma concentration, while maintaining electrical resistance to prevent unwanted ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second contact surface of the n-doped firing stage emitter is spaced from the p-doped base, then the net dopant concentration of the p-doped base can be locally increased to enhance amplification factor, but the area of the p-doped base available for achieving minimum voltage is reduced
Solution Approach 1:
The p-doped base is segmented into a first region with increased net dopant concentration positioned between the n-doped firing stage emitter and n-doped main emitter to provide enhanced amplification factor and residual plasma concentration, and a second region with lower net dopant concentration that provides sufficient area for achieving the minimum ignition voltage through voltage drop.
2Quantity of substance
If the net dopant concentration of the p-doped base is increased, then the amplification factor and residual plasma concentration are enhanced for targeted ignition, but the electrical resistance decreases making it harder to reach the critical voltage threshold
Solution Approach 1:
The p-doped base is divided into regions with different net dopant concentrations: the first region has increased concentration to enhance residual plasma concentration and amplification factor for targeted ignition during reverse recovery time, while the second region maintains lower concentration to preserve electrical resistance necessary for reaching the minimum ignition voltage.
Solution Approach 2:
Different regions of the p-doped base are assigned different dopant concentrations according to their specific functional requirements: the region between the n-doped firing stage emitter and n-doped main emitter has increased dopant concentration for high amplification factor and residual plasma concentration, while other regions have lower dopant concentration to maintain the electrical resistance needed for voltage drop and ignition.
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 design allows for targeted ignition during voltage pulses with critical time derivatives, ensuring the thyristor operates safely and effectively by compensating for increased dopant concentration with increased electrical resistance, preventing premature ignition.
Implementation Method 1
This creates the possibility of locally increasing the net dopant concentration of the p-doped base compared to a conventional thyristor in the area of the relevant n-doped firing stage emitter, which means an increase in the amplification factor β pnp of the relevant n-doped firing stage emitter from the p-doped base, the n-doped base and the p-doped emitter formed pnp transistor causes. Such an increase in the amplification factor β pnp leads to an increase in the concentration of the residual plasma in the region of the ignition stage in question during the reverse recovery time.
Implementation Method 2
Since the second contact surface of a thyristor according to the present invention is at a distance from the associated n-doped firing stage emitter, the area of the p-doped base that is decisive for achieving the aforementioned minimum voltage is increased and, as a result, the electrical resistance that is decisive for achieving the minimum voltage is increased.
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
The invention relates to a thyristor comprising a semiconductor body (1), in which a p-doped emitter (8), an n-doped base (7), a p-doped base (6) and an n-doped emitter (5) are disposed consecutively in a vertical direction (v), starting a rear side (14) toward a front side (13) located opposite of the rear side (14). Furthermore, a trigger stage structure (AG) comprising at least one trigger stage (AG1, AG2, AG3, AG4) is provided, each stage comprising an n-doped trigger stage emitter (51, 52, 53, 54) that is spaced apart from the n-doped emitter (5) and embedded in the p-doped base (6). A trigger stage electrode (42) contacts one (52) of the trigger stage emitters (51, 52, 53, 54) at the front side (13) and has a first contact surface (421) with the latter. On a second contact surface (422), the trigger stage electrode (42) contacts the p-doped base (6) on the side of the one (52) trigger stage emitter at the front side (13) that faces the n-doped emitter (5). The second contact surface (422) is spaced apart both from the first contact surface (421) and from the one (52) trigger stage emitter.