SiC MOSFET Gate ESD Circuit Using Bipolar Current Boost
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Solution Overview
Problem
Semiconductor devices using silicon carbide substrates face challenges in achieving sufficient electrostatic withstand voltage while maintaining cost-effectiveness due to low anode current in the second protection diode, leading to increased area requirements and costs.
Innovation Solution
Incorporating a bipolar transistor and adjusting its structure and resistance element to complement the anode current of the second protection diode, allowing for increased current flow and reduced area requirements, thereby enhancing electrostatic protection without increasing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second protection diode is used in the electrostatic protection circuit, then the device can provide protection functionality, but the anode current is low requiring larger diode area which increases cost
Solution Approach 1:
The patent combines the second protection diode with a bipolar transistor to form a composite protection structure. The bipolar transistor's collector current complements the diode's anode current, providing sufficient electrostatic protection current without requiring a large diode area, thus reducing manufacturing cost while maintaining protection reliability.
Solution Approach 2:
The patent modifies the protection circuit by introducing a bipolar transistor with specific current gain characteristics. The transistor's current amplification capability transforms the low anode current of the second protection diode into a sufficient protection current, changing the electrical parameters of the protection path without increasing physical area.
2Reliability
If the diode area is increased to compensate for low anode current, then sufficient electrostatic withstand voltage can be achieved, but the device area and cost increase
Solution Approach 1:
The patent merges the second protection diode with a bipolar transistor in a compact configuration. The transistor provides current amplification that compensates for the diode's low anode current, achieving sufficient electrostatic withstand voltage without increasing the diode area, thus maintaining small device footprint while ensuring protection reliability.
3Ease of manufacture
If a bipolar transistor is added to complement the anode current, then sufficient protection current can be achieved with smaller area, but the device complexity increases
Solution Approach 1:
The patent integrates the bipolar transistor and second protection diode into a unified protection element where the transistor's collector and emitter are connected to complement the diode terminals. This merging approach provides current amplification functionality while maintaining a simple external interface, adding minimal structural complexity while achieving cost reduction through smaller area requirements.
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 effectively suppresses the need for larger diode areas, securing sufficient electrostatic withstand voltage while reducing the overall cost and improving the reliability of the semiconductor device.
Implementation Method 1
Incorporating a bipolar transistor and adjusting its structure and resistance element to complement the anode current of the second protection diode, allowing for increased current flow
Data Source
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AI summary
A semiconductor device includes an electrostatic protection circuit 1 and a MOSFET 2 including a gate terminal. The electrostatic protection circuit 1 includes a positive-side power supply terminal 3, a negative-side power supply terminal 5, a first protection diode 4, a second protection diode 6, a resistance element 7, and a bipolar transistor 8. The second protection diode 6 includes an anode terminal electrically connected to the negative-side power supply terminal 5 via the resistance element 7, and a cathode terminal electrically connected to the gate terminal. The bipolar transistor 8 includes a base terminal, an emitter terminal, and a collector terminal. The bipolar transistor 8 is electrically connected to the anode terminal of the second protection diode 6, the gate terminal, and the positive-side power supply terminal 3. The electrostatic protection circuit 1 is formed on a semiconductor substrate made of silicon carbide.