SiC Epitaxial Substrate Defect Screening for Device Reliability

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Solution Overview

Problem

Existing silicon carbide semiconductor devices face reliability issues due to the presence of internal line-shaped stacking faults and carrot defects, which are difficult to detect and can lead to performance deterioration post-shipment.

Innovation Solution

A silicon carbide epitaxial substrate is designed with a specific ratio of internal line-shaped stacking fault dimensions and carrot defect dimensions, where the number of internal line-shaped stacking faults is less than the number of carrot defects, and the substrate is manufactured using controlled propane gas flow rates during epitaxial growth to minimize these defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If internal line-shaped stacking faults are present in the silicon carbide epitaxial layer, then device manufacturing can proceed, but reliability deteriorates due to undetected defects

Engineering Contradiction:

Improvedevice reliabilityVSAvoiddefect detectability

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent utilizes photoluminescence imaging to detect defects. Carrot defects emit red light while internal line-shaped stacking faults emit green light, creating color-based visual differentiation. This allows non-destructive detection of normally invisible internal defects through optical property changes, resolving the contradiction between maintaining device integrity and detecting hidden defects.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent replaces traditional mechanical or electrical detection methods with optical detection using photoluminescence imaging. By substituting the detection mechanism with optical properties, the system can non-contact, non-destructively identify internal stacking faults and carrot defects, improving both reliability assessment and detectability simultaneously.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If carrot defects are present in the silicon carbide epitaxial layer, then manufacturing complexity increases, but reliability improves due to easier defect identification

Engineering Contradiction:

Improvedevice reliabilityVSAvoiddefect structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Carrot defects exhibit distinct red photoluminescence emission, providing visual complexity that aids detection. This color-based differentiation transforms the complexity of defect identification into a beneficial diagnostic feature, allowing easy distinction between carrot defects (red) and internal stacking faults (green) without additional detection equipment.

Inventive Principle:

Principle #32Color changes

3Reliability

If the number of internal line-shaped stacking faults is reduced, then reliability improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvedevice reliabilityVSAvoidepitaxial growth precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary detection of internal line-shaped stacking faults using photoluminescence imaging before final device assembly. By detecting and mapping defect locations in advance, manufacturers can plan device fabrication to avoid defective regions or apply targeted remediation, reducing the need for ultra-high precision manufacturing throughout the entire process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables localized assessment of defect density and distribution through photoluminescence imaging. Rather than requiring uniform high precision across the entire wafer, manufacturers can identify specific regions with internal stacking faults and adjust processing parameters or device layout locally, reducing overall manufacturing precision requirements while maintaining reliability.

Inventive Principle:

Principle #3Local quality

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 enhances the reliability of silicon carbide semiconductor devices by ensuring that devices with internal line-shaped stacking faults are not shipped, while readily identifying and rejecting those with carrot defects, thereby reducing the risk of reliability failures.

Implementation Method 1

silicon carbide epitaxial layer, located on the silicon carbide substrate

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Data Source

PatentUS20250218771A1Silicon carbide epitaxial substrate and method of manufacturing silicon carbide semiconductor device

Publication Date: 2025.07.03 MITSUMI ELECTRIC CO LTD

AI summary

A silicon carbide epitaxial substrate has a silicon carbide substrate, a silicon carbide epitaxial layer, an internal line-shaped stacking fault, and a carrot defect. The silicon carbide epitaxial layer is located on the silicon carbide substrate and has a main surface. The internal line-shaped stacking fault is located inside the silicon carbide epitaxial layer and is separated from the main surface. The carrot defect is exposed at the main surface. A value obtained by dividing a length of the internal line-shaped stacking fault by a width of the internal line-shaped stacking fault is 0.5 or less. A value obtained by dividing a length of the carrot defect by a width of the carrot defect is more than 0.5. The number of the internal line-shaped stacking faults is less than the number of the carrot defects.