Power Semiconductor Bevel Structure for Cooler Termination Regions

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Solution Overview

Problem

Power semiconductor devices face challenges in reducing emitter injection efficiency and heat generation in the termination region, leading to thermal instability during high-frequency operations or surge current events, especially at elevated temperatures.

Innovation Solution

The power semiconductor device incorporates a combination of semiconductor layers and an oxide layer, with a bevel structure and passivation, to effectively disconnect the termination region electrically and reduce emitter injection efficiency, while the oxide layer is applied using PECVD processes to enhance thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the termination region is electrically connected to reduce emitter injection efficiency, then device reliability improves, but heat generation increases causing thermal instability

Engineering Contradiction:
Improvedevice reliabilityVSAvoidheat generation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The termination region is segmented into multiple regions with different oxide layer configurations. First oxide layers are formed on portions of the first semiconductor layer in the termination region, while second oxide layers are formed on portions of the second semiconductor layer. This segmentation allows different areas to have different emitter injection efficiencies, enabling electrical connection for reliability while managing heat generation through regional differentiation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different oxide layer configurations are applied to different locations within the termination region. The first oxide layers and second oxide layers have different properties and are positioned at different locations, creating local quality variations. This allows the device to have high emitter injection efficiency where needed for reliability while maintaining lower heat generation in other areas, resolving the contradiction between reliability and heat management.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If emitter injection efficiency is reduced in the termination region, then thermal stability improves, but device performance deteriorates

Engineering Contradiction:
Improvethermal stabilityVSAvoiddevice performance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The termination region is divided into multiple segments with different oxide layer configurations. By segmenting the termination region and applying different oxide layers selectively, the device achieves reduced emitter injection efficiency in specific areas for thermal stability while maintaining adequate performance through the overall device structure and other functional regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different oxide layer properties are applied locally within the termination region. The first oxide layers and second oxide layers create local quality differences that allow thermal stability in areas where it is most needed while preserving device performance through the combined effect of all regions. This local differentiation resolves the contradiction between thermal stability and overall device performance.

Inventive Principle:
Principle #3Local quality

3Reliability

If oxide layers are formed on both semiconductor layers in the termination region, then emitter injection efficiency is reduced, but device complexity increases

Engineering Contradiction:
Improveemitter injection efficiency controlVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The oxide layer formation is segmented into two types: first oxide layers on the first semiconductor layer and second oxide layers on the second semiconductor layer. This segmentation allows for controlled reduction of emitter injection efficiency while maintaining a systematic fabrication process. The segmented approach manages complexity by organizing the oxide layer formation into distinct, manageable steps rather than a single complex process.

Inventive Principle:
Principle #1Segmentation

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 configuration reduces emitter injection efficiency, minimizes heat generation in the termination region, and increases thermal stability, enabling the device to operate at higher temperatures with improved cooling capabilities.

Implementation Method 1

an oxide layer extending in an active region of the power semiconductor device being surrounded by a termination region of the power semiconductor device is arranged on at least one of the first semiconductor layer and the second semiconductor layer

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 2

the oxide layer is applied using PECVD processes

Methodology Applied
Scientific EffectPlasma enhanced chemical vapor deposition: Plasma Enhanced Chemical Vapour Deposition

Data Source

PatentEP4439680A1Power semiconductor device and method for producing a power semiconductor device
Publication Date: 2024.10.02 HITACHI ENERGY LTD
  • EP4439680A1 patent drawingFigure 1~2
  • EP4439680A1 patent drawingFigure 3~4
  • EP4439680A1 patent drawingFigure 5

AI summary

A power semiconductor device (1) is specified, comprising - a first electrode (2), - a first semiconductor layer (3) of a first conductivity type, - a drift layer (4) of the first conductivity type, - a second semiconductor layer (5) of a second conductivity type different from the first conductivity type, and - a second electrode (6), wherein - at least one of the first semiconductor layer (3) and the second semiconductor layer (5) comprises an oxide layer (24) extending in an active region (9) of the power semiconductor device (1) being surrounded by a termination region (8) of the power semiconductor device (1), and - at least one of the first semiconductor layer (3) and the second semiconductor layer (5) has a bevel structure (19). Furthermore, a method for producing a power semiconductor device (1) is specified.