Split-Gate IGBT Electrode Structure for Lower Electromagnetic Noise
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Solution Overview
Problem
Existing insulated gate bipolar transistors (IGBTs) face challenges in reducing electromagnetic noise due to high gate-emitter capacitance, which increases switching loss and electromagnetic interference.
Innovation Solution
A semiconductor device with a structure that includes separate upper and lower electrodes, each connected to different resistors, where the gate-emitter capacitance of the lower electrode is smaller than that of the upper electrode, reducing electromagnetic noise by controlling the voltage and capacitance independently.
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 controlled independently with different voltages, allowing separate optimization of switching speed and electromagnetic 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: 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. This local differentiation allows simultaneous achievement of fast switching and low electromagnetic noise.
2Productivity
If gate voltage Vge is increased to improve switching performance, then switching performance improves, but electromagnetic noise increases due to higher displacement current
Solution Approach 1:
The gate voltage control is segmented into two independent control paths: one for the first gate electrode and another for the second gate electrode. This allows the first electrode to receive high voltage for performance while the second electrode receives low voltage for noise suppression, resolving the contradiction between performance and noise.
Solution Approach 2:
Different voltage parameters are applied to different gate electrodes: the first gate electrode is supplied with a first voltage optimized for switching performance, while the second gate electrode is supplied with a second voltage optimized for minimizing displacement current and electromagnetic noise. This parameter differentiation resolves the contradiction.
3Object-generated harmful factors
If Cgc/Cge ratio is decreased to reduce electromagnetic noise, then electromagnetic noise decreases, but switching speed and performance are compromised
Solution Approach 1:
The gate control is segmented into two independent electrodes that can be optimized for different functions. The first gate electrode maintains the traditional capacitance characteristics for fast switching, while the second gate electrode is designed to control displacement current and reduce electromagnetic noise, allowing both requirements to be met simultaneously.
Solution Approach 2:
Different regions of the gate structure have different capacitance characteristics: the first gate electrode region is optimized for fast charging (low Cge) to achieve high switching speed, while the second gate electrode region is optimized for displacement current control (appropriate Cgc) to reduce electromagnetic noise. This local optimization resolves the contradiction.
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 structure effectively reduces electromagnetic noise by increasing the charging speed of the lower electrode's capacitance, decreasing the gate-collector capacitance, and minimizing the IC peak, thereby improving the IGBT's performance and reducing switching loss.
Implementation Method 1
a lower gate insulating film covering a side surface and a bottom surface of the lower electrode; an upper gate insulating film covering a side surface of the upper electrode
Implementation Method 2
separated from the lower electrode by an intermediate insulating film
Implementation Method 3
gate-emitter capacitance of the lower electrode is smaller than gate-emitter capacitance of the upper electrode
Implementation Method 4
Vge increases as a displacement current (Idis=Cgc×dV/dt) is higher and Cge is smaller
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 input terminal. A second resistor is connected between the lower electrode and the input terminal. Gate-emitter capacitance of the lower electrode is smaller than gate-emitter capacitance of the upper electrode.