Split Trench Gate Electrode Structure for Low-Noise IGBT Switching
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Solution Overview
Problem
Existing insulated gate bipolar transistors (IGBTs) face challenges in reducing electromagnetic noise due to high gate-collector capacitance and gate-emitter capacitance ratios, which increase switching loss and noise levels.
Innovation Solution
A semiconductor device with a unique structure featuring separate upper and lower electrodes, each with different gate-emitter capacitances, connected by resistors, to control voltage differences and reduce capacitance ratios, thereby minimizing electromagnetic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching speed is increased to reduce switching loss, then switching loss decreases, but electromagnetic noise increases
Solution Approach 1:
The gate electrode is divided into two separate electrodes: a first gate electrode and a second gate electrode. Each electrode can be independently controlled with different voltages, allowing separate optimization of switching speed and noise reduction. The first gate electrode controls the main switching operation while the second gate electrode suppresses electromagnetic noise by controlling displacement current.
Solution Approach 2:
Different regions of the gate structure are assigned different functions with different voltage controls. The first gate electrode region is optimized for fast switching by applying higher voltage, while the second gate electrode region is optimized for noise suppression by applying lower voltage, creating local quality differences in the gate control.
2Speed
If gate voltage Vge overshoot is increased to improve switching speed, then switching speed increases, but electromagnetic noise increases due to higher displacement current
Solution Approach 1:
The gate control is segmented into two independent voltage controls applied to different gate electrodes. The first gate electrode can be rapidly charged to achieve fast switching, while the second gate electrode is controlled separately to suppress displacement current and reduce electromagnetic noise during the switching transition.
Solution Approach 2:
Different voltage parameters are applied to different gate electrodes simultaneously. The first gate electrode receives a higher voltage for fast switching, while the second gate electrode receives a lower voltage to suppress displacement current. This parameter differentiation allows independent optimization of switching speed and noise reduction.
3Object-generated harmful factors
If gate-collector capacitance Cgc is reduced to decrease Cgc/Cge ratio, then electromagnetic noise decreases, but device structure becomes more complex
Solution Approach 1:
Instead of modifying the physical structure to reduce Cgc, the invention segments the gate control into two independent electrodes. This allows electrical control of the effective Cgc/Cge ratio through voltage management rather than structural changes, reducing electromagnetic noise without significantly increasing device structural complexity.
Solution Approach 2:
The invention changes the electrical parameters (voltages) applied to different gate electrodes rather than changing the physical structure. By controlling the voltage on the second gate electrode, the effective capacitance ratio Cgc/Cge can be dynamically adjusted to reduce electromagnetic noise without modifying the device geometry or adding complex structural elements.
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 device effectively reduces electromagnetic noise by optimizing capacitance ratios and voltage control, leading to decreased switching loss and improved performance.
Implementation Method 1
gate-emitter capacitance of the lower electrode is smaller than gate-emitter capacitance of the upper electrode
Implementation Method 2
via a lower gate insulating film; an upper electrode formed inside the trench via an upper gate insulating film
Implementation Method 3
positioned above the lower electrode and separated from the lower electrode by an intermediate insulating film
Implementation Method 4
a first resistor connected between the upper electrode and the gate electrode; and a second resistor connected between the lower electrode and the gate electrode
Data Source
AI summary
An upper electrode is separated from a lower electrode inside a trench by an intermediate insulating film. A first resistor is connected between the upper electrode and the gate electrode. A second resistor is connected between the lower electrode and the gate electrode. Gate-emitter capacitance of the lower electrode is smaller than gate-emitter capacitance of the upper electrode.