Beta-Ga2O3 Single Crystal Substrate EFG Growth

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Solution Overview

Problem

Conventional methods for growing β-Ga2O3 single crystals result in low-quality substrates with high dislocation densities and poor crystal orientation, limiting their application in advanced semiconductor devices.

Innovation Solution

A new method involving an Edge Defined Film Fed Growth (EFG) process with an after-heater and reflective plate is used to grow β-Ga2O3 single crystals, reducing full width at half maximum (FWHM) of x-ray rocking curves and average dislocation density, while avoiding twinning and broadening processes that degrade crystal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional EFG method is used to grow β-Ga2O3 single crystal, then crystal growth is achieved, but the crystal quality is low with high dislocation density and poor orientation

Engineering Contradiction:
Improvecrystal qualityVSAvoiddislocation density
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the pulling speed (0.1-10 mm/h) and rotation speed (0.1-10 rpm) of the seed crystal, along with controlling the temperature gradient in the growth chamber. These parameter optimizations enable high-quality crystal growth with reduced dislocation density while maintaining reliable crystal structure

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic control during crystal growth by continuously adjusting the pulling speed and rotation speed of the seed crystal based on real-time growth conditions. This dynamic adjustment allows the system to maintain optimal growth conditions throughout the process, achieving both high crystal quality and low dislocation density

Inventive Principle:
Principle #15Dynamics

2Area of moving object

If conventional EFG method broadens crystal width from seed crystal, then larger width crystal is obtained, but crystal quality degrades with increased dislocation density

Engineering Contradiction:
Improvecrystal widthVSAvoidcrystal quality
Core Design Contradiction:
Area of moving objectVSManufacturing precision

Solution Approach 1:

The patent uses dynamic control of the seed crystal rotation and pulling speed during the width-broadening process. By continuously adjusting these parameters, the system maintains optimal growth conditions even as the crystal width increases, preventing quality degradation and dislocation formation

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent optimizes growth parameters including pulling speed (0.1-10 mm/h) and rotation speed (0.1-10 rpm) to achieve width broadening while maintaining crystal quality. These controlled parameter changes enable the crystal to expand in width without compromising structural integrity or increasing dislocation density

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If conventional methods are used, then crystal growth is achieved, but FWHM of x-ray rocking curve is high indicating poor orientation

Engineering Contradiction:
Improvecrystal orientationVSAvoidFWHM of x-ray rocking curve
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent optimizes growth parameters including temperature gradient, pulling speed (0.1-10 mm/h), and rotation speed (0.1-10 rpm) to achieve superior crystal orientation. These controlled parameter changes result in reduced FWHM values in x-ray rocking curves, indicating improved orientational precision of the crystal lattice

Inventive Principle:
Principle #35Parameter changes

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

The method produces β-Ga2O3 single crystal substrates with improved crystal quality, characterized by reduced FWHM and dislocation density, enabling better orientation and reduced twinning, which is essential for high-performance semiconductor applications.

Implementation Method 1

To grow a β-Ga2O3 single crystal by EFG method

Methodology Applied
Scientific EffectCrystallisation: Crystallisation

Implementation Method 2

a temperature gradient in a hot zone is formed in the radial direction

Methodology Applied
Scientific EffectTemperature Gradient: Temperature Gradient

Data Source

PatentEP2924150B1ß-GA2O3-BASED SINGLE CRYSTAL SUBSTRATE
Publication Date: 2017.11.22 TAMURA KK
  • EP2924150B1 patent drawingFigure 1A~1B
  • EP2924150B1 patent drawingFigure 2A~2B
  • EP2924150B1 patent drawingFigure 3A~3C

AI summary

A β-Ga2O3-based single crystal substrate includes a β-Ga2O3-based single crystal. The β-Ga2O3-based single crystal includes a full width at half maximum of an x-ray rocking curve of less than 75 seconds.