Trench Semiconductor Switch Electrode for Loss Reduction
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Solution Overview
Problem
Existing power semiconductor devices, such as IGBTs, face challenges in reducing switching losses while maintaining low saturation voltage, as current methods either integrate p-channel FETs or form narrow mesa structures, which have limitations in efficiency and complexity.
Innovation Solution
The semiconductor device incorporates a switch electrode and a gate electrode arranged in a trench structure, with the switch electrode generating a potential barrier to accumulate minority charge carriers in the drift region, reducing saturation voltage and switching losses by controlling the charge carrier distribution, and adjusting the voltage applied to the switch electrode before switching off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If p-channel field effect transistor is integrated parallel to n-channel field effect transistor, then switching losses are reduced, but device complexity increases
Solution Approach 1:
The patent extracts the hole extraction function from a separate p-channel FET and implements it through a switch electrode that can be integrated into the existing trench structure. This eliminates the need for a parallel p-channel FET while maintaining the hole extraction capability, thereby reducing device complexity while still reducing switching losses.
Solution Approach 2:
The switch electrode serves multiple functions: it acts as a gate electrode for controlling the conductive channel, and simultaneously functions to extract holes from the drift region by generating an attractive force on minority charge carriers. This multi-functionality replaces the need for separate p-channel FET structure.
2Strength
If narrow mesa structures are formed between trenches, then saturation voltage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
Instead of relying on precise control of mesa structure width, the patent changes the approach by using electrical parameter control (voltage applied to the switch electrode) to achieve the desired saturation voltage reduction. The switch electrode generates a potential barrier that attracts holes, and this effect can be controlled by adjusting the voltage parameter rather than relying on precise geometric dimensions.
3Loss of energy
If switch electrode is added to control charge carrier distribution, then switching losses are reduced, but device complexity increases
Solution Approach 1:
The patent merges the switch electrode and gate electrode functions into a single integrated structure within the trench. The switch electrode is positioned in the drift region and can be controlled independently to extract holes, while the gate electrode controls the main conductive channel. This integration achieves hole extraction functionality without adding separate external control circuits or structures.
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 approach effectively reduces switching losses and saturation voltage by managing charge carrier flow, leading to improved efficiency and reduced power dissipation during switching operations.
Implementation Method 1
the switch electrode generating a potential barrier to accumulate minority charge carriers in the drift region
Implementation Method 2
applying a first on-voltage of a second polarity to the gate electrode to generate a conductive channel in the body region
Implementation Method 3
adjusting the voltage applied to the switch electrode before switching off to manage charge carrier flow
Data Source
AI summary
A semiconductor device with switch electrode and gate electrode and a method for switching a semiconductor device. One embodiment provides a semiconductor substrate with an emitter region, a drift region, a body region and a source region. The drift region is formed between the emitter and the body region while the body region is formed between the drift and the source region. A first trench structure extends from the source region at least partially into the drift region. The first trench structure includes a gate electrode arranged next to the body region and a switch electrode arranged in portions next to the drift region, wherein the switch and gate electrodes are electrically insulated from each other in the trench structure. A first gate driver is electrically connected to the gate electrode while a second gate driver is electrically connected to the switch gate.