Multi-Zone IGBT With Staged Switching For Loss Trade-Off

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Solution Overview

Problem

Existing power semiconductor devices, particularly bipolar types, face a trade-off between conduction loss and switching loss, where optimizing one aspect typically increases the other, making it difficult to achieve a low-loss conduction state and low-loss switching behavior in the same chip.

Innovation Solution

The design of Insulated Gate Bipolar Transistors (IGBTs) with multiple zones, each having distinct switching losses and doping densities, where zones with higher switching losses transition to a non-conducting state before those with lower switching losses, utilizing different recombination lifetime treatments and gate insulation thicknesses to manage switching and conduction losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the device is optimized for low switching loss, then switching performance is improved, but conduction loss increases

Engineering Contradiction:

Improveswitching lossVSAvoidconduction loss

Core Design Contradiction:

Loss of energyVSLoss of energy

Solution Approach 1:

The device is divided into multiple zones with different doping densities and switching characteristics. Fast-switching zones have higher doping densities optimized for low switching loss, while slow-switching zones have lower doping densities optimized for low conduction loss. This segmentation allows the device to achieve both low switching loss and low conduction loss simultaneously by having different zones perform different functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different zones within the device have locally optimized properties: fast-switching zones have higher doping densities and are configured for rapid switching, while slow-switching zones have lower doping densities and are configured for efficient conduction. Each zone's properties are tailored to its specific function, resolving the global trade-off between switching loss and conduction loss.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If zones with higher switching losses transition later, then conduction loss is reduced, but overall switching loss increases

Engineering Contradiction:

Improveconduction lossVSAvoidswitching loss

Core Design Contradiction:

Loss of energyVSLoss of energy

Solution Approach 1:

The patent inverts the conventional approach by having zones with higher switching losses transition earlier rather than later. Fast-switching zones with higher doping densities are designed to switch off first, carrying the switching loss burden, while slow-switching zones with lower doping densities transition later and maintain conduction efficiency. This inversion resolves the trade-off by assigning different temporal roles to different zones.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

Fast-switching zones are configured to transition to the non-conducting state before slow-switching zones. This preliminary action in the fast-switching zones allows the main current switching to occur early, while the slow-switching zones continue conducting at lower currents, thereby reducing overall conduction loss while managing switching losses through the staged transition.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9793386B2Multiple zone power semiconductor device

Publication Date: 2017.10.17 FORD GLOBAL TECH LLC

AI summary

A power semiconductor device is comprised of a plurality of zones having similar structure. Each of the zones may be characterized by a switching loss during transitions to a non-conducting state. The device is configured such that the switching loss is different between at least two of the zones. Further, the device is configured such that zones having greater switching losses transition to the non-conducting state before zones having lesser switching losses.