Power Semiconductor Barrier Region for Gate Oxide Robustness

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Solution Overview

Problem

Power semiconductor devices face challenges in achieving a balance between long-term stability and robustness to gate insulator degradation, particularly during high-frequency and harsh switching conditions, where existing solutions either compromise on static loss or fail to ensure long-term performance.

Innovation Solution

Incorporating a barrier region between the drift region and the extraction electrode, which shields additional extraction contacts and reduces detrimental effects on the on-state while maintaining improved robustness to gate oxide degradation, thereby achieving a trade-off between long-term stability and static loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If extraction regions are provided between emitter trenches to improve robustness to gate insulator degradation, then long-term stability is improved, but static loss increases

Engineering Contradiction:
Improverobustness to gate insulator degradationVSAvoidstatic loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a barrier region with different doping characteristics (higher doping concentration) in specific locations between the drift region and extraction electrode. This localized modification allows the barrier region to selectively block carrier extraction in the on-state (reducing static loss) while still permitting degradation charge extraction during off-state (improving robustness to gate insulator degradation). The barrier region's specific electrical properties are tailored to achieve different functions in different operational states.

Inventive Principle:
Principle #3Local quality

2Reliability

If additional extraction contacts are added to improve robustness to gate oxide degradation, then long-term stability is improved, but device complexity increases

Engineering Contradiction:
Improverobustness to gate oxide degradationVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the barrier region functionality with the existing drift region structure. The barrier region is formed as an extension of the drift region through continued doping, integrating the new functionality into the existing device architecture rather than adding completely separate structures. This merging approach reduces device complexity by utilizing existing structural elements and process steps while still achieving improved robustness to gate oxide degradation.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If barrier region is introduced to reduce static loss, then energy efficiency is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvestatic lossVSAvoidmanufacturing complexity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by forming the barrier region through a doping process that occurs before final device assembly and characterization. The barrier region is created during the manufacturing process itself, allowing its electrical properties to be established and optimized before the device is put into service. This preliminary formation of the barrier region with specific doping concentrations and profiles enables subsequent optimization of static loss performance without requiring complex post-manufacturing adjustments.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4203069B1Power semiconductor device and manufacturiing method
Publication Date: 2024.07.03 HITACHI ENERGY LTD
  • EP4203069B1 patent drawingFigure 1~3
  • EP4203069B1 patent drawingFigure 4~5
  • EP4203069B1 patent drawingFigure 6~7

AI summary

In at least one embodiment, the power semiconductor device (1) comprises: - a semiconductor body (2), - a gate electrode (31), and - an extraction electrode (34), wherein the semiconductor body (2) comprises - a source region (21) of a first conductivity type, - a well region (22) of a second conductivity type different from the first conductivity type at the gate electrode (31), - a drift region (23) which is of the first conductivity type, and - a barrier region (28) which is of the first conductivity type, the barrier region (28) is located between the drift region (23) and the extraction electrode (34).