SCR Layer Structure for Low-Voltage Fast Turn-On
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Solution Overview
Problem
Existing semiconductor controlled rectifier devices fail to simultaneously achieve low capacitance, low trigger voltage, fast turn-on, and low on-resistance, particularly in modern circuits with low supply voltage and fast data rates.
Innovation Solution
A semiconductor device is designed with a layered structure comprising doped regions of different charge carriers forming bipolar junction transistors, where a junction element functions as a short or resistor between base contacts, reducing trigger voltage and capacitance by creating forward-biased emitter-base junctions, thereby eliminating the need for additional trigger diodes and sophisticated isolation schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex trigger structures are used in existing semiconductor controlled rectifiers, then the device can achieve reliable triggering, but the capacitance increases and trigger voltage cannot be reduced to the required levels
Solution Approach 1:
The patent changes the doping parameters of the semiconductor layers, specifically creating a high dopant region in the third layer with doping concentration higher than the base layer, to achieve low capacitance while maintaining reliable triggering through the simplified two-layer structure
Solution Approach 2:
The patent extracts and eliminates the separate trigger diode component from the device structure, integrating the triggering function directly into the bipolar junction transistor structure itself, thereby reducing overall device capacitance while maintaining triggering reliability
2Power
If additional trigger diodes are added to reduce trigger voltage, then the trigger voltage decreases, but the device complexity and capacitance increase
Solution Approach 1:
The patent merges the trigger function with the main power transistor structure by creating a bipolar junction transistor where the base-collector junction serves as the trigger path, eliminating the need for separate trigger diodes and reducing device complexity
Solution Approach 2:
The bipolar junction transistor structure performs multiple functions simultaneously: it acts as both the power switching element and the triggering element, with the base-collector junction providing the low-voltage trigger path while the emitter-collector path handles the main power current
3Power
If the emitter-base junction has high capacitance, then the device can handle higher current, but the turn-on speed decreases and capacitance increases
Solution Approach 1:
The patent applies local quality by creating a high dopant region specifically in the third layer adjacent to the second layer, while keeping other regions with appropriate doping levels, thereby achieving low capacitance at the critical emitter-base junction while maintaining overall current handling capability
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 achieves low capacitance and fast turn-on with reduced trigger voltage, simplifying the device configuration and enhancing performance in modern circuits.
Implementation Method 1
Injection of minority carriers starts from both sides and the turn-on effect is fast
Implementation Method 2
At least one of the emitter base junctions has a low capacitance, therefore, the semiconductor controlled rectifier has a low capacitance, too
Data Source
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AI summary
According to a first example of the disclosure, a semiconductor device is proposed, which comprises a first layer doped with a first type of charge carriers; a second layer doped with a second type of charge carriers different from the first type of charge carriers; a third layer doped with the first type of charge carriers; a fourth layer doped with the second type of charge carriers; and an input terminal electrically connected with the first layer and an output terminal electrically connected with the fourth layer. The first, second and third layer form a first bipolar junction transistor, BJT, and the second, third and fourth layer form a second bipolar junction transistor, BJT. Additionally, a junction element is provided which electrically connects the second layer with the third layer. Furthermore, the third layer comprises a high dopant region adjoining the second layer. The electrical junction element functions as a short between the two base contacts of each BJT. It reduces the trigger voltage to the equivalent of two forward biased diodes. When the device gets triggered, both emitter base junctions, between the first-second layer and fourth-third layer, are forward biased at the same time. Injection of minority carriers starts from both sides and the turn-on effect is fast. At least one of the emitter base junctions has a low capacitance, therefore, the semiconductor controlled rectifier has a low capacitance, too.