Group III Nitride Seed Substrate with Enlarged Hexagonal Regions

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Solution Overview

Problem

Existing methods for producing GaN crystals, such as the Na flux method using a multi-point seed substrate, face challenges in achieving a large area while minimizing dislocation density and warpage, particularly when seed crystals are arranged in a regular hexagonal pattern, which reduces the grown GaN area.

Innovation Solution

A method and seed substrate design where seed crystals are arranged within a hexagonal region with enlarged trapezoidal regions continuous with the hexagonal sides, allowing for increased area growth by optimizing the disposition pattern to reduce irregularities and enhance crystal combination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If seed crystals are arranged in a regular hexagonal pattern to reduce irregularities and cracks, then manufacturing precision and reliability improve, but the area of grown GaN decreases

Engineering Contradiction:

Improveregularity of outer peripheryVSAvoidarea of grown GaN

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The invention modifies the symmetric hexagonal pattern by adding enlarged regions to specific sides, creating an asymmetric disposition region that maintains the regularity benefits while expanding the growth area. The enlarged regions are added to at least two adjacent sides among the six sides of the hexagon, breaking the perfect symmetry to achieve larger area utilization.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention extends the disposition region beyond the basic hexagonal boundary by adding enlarged regions that protrude outward from the hexagon sides. This dimensional extension allows the seed crystal arrangement to occupy a larger area while maintaining the hexagonal structural benefits for reducing irregularities.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the disposition region is enlarged to increase GaN growth area, then productivity improves, but irregularities and cracks on the outer periphery increase

Engineering Contradiction:

Improvearea of GaN growthVSAvoidregularity of outer periphery

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The asymmetric addition of enlarged regions to specific hexagon sides allows selective expansion in directions that maximize area while minimizing the creation of irregularities. By strategically placing enlargements on adjacent sides rather than all sides, the design achieves area increase with controlled impact on peripheral regularity.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The enlarged regions are applied locally to specific sides of the hexagon rather than uniformly to all sides. This local quality approach allows the disposition region to be expanded in areas where it provides maximum benefit while maintaining the regular hexagonal structure in other areas, thus balancing area increase with irregularity reduction.

Inventive Principle:

Principle #3Local quality

3Reliability

If a hexagonal disposition region is used to prevent cracks, then reliability improves, but the area utilization is reduced compared to circular patterns

Engineering Contradiction:

Improvecrack preventionVSAvoidarea of disposition region

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The invention segments the hexagonal structure by adding distinct enlarged regions to specific sides, creating a composite shape that combines the crack-prevention benefits of hexagonal geometry with the area efficiency of extended regions. This segmentation allows the disposition region to maintain structural integrity while expanding into underutilized spaces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges the hexagonal region with additional enlarged regions to create a composite disposition region. This combination integrates the advantages of both shapes: the hexagonal core provides crack prevention through its regular geometry, while the attached enlarged regions increase the total area for seed crystal arrangement and GaN growth.

Inventive Principle:

Principle #5Merging (Combining)

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 and substrate design enable larger area growth of Group III nitride semiconductors with reduced peripheral irregularities and dislocation, enhancing crystal uniformity and reducing warpage.

Implementation Method 1

dissolving nitrogen in the melt

Methodology Applied

Scientific EffectDissolution: Solvation

Data Source

PatentUS20250320631A1Seed substrate and method for producing group iii nitride semiconductor

Publication Date: 2025.10.16 TOYODA GOSEI CO LTD

AI summary

A method for producing a Group III nitride semiconductor includes: preparing a seed substrate including a substrate on which plural seed crystals, each made from a Group III nitride semiconductor, are discretely disposed; and bringing the plural seed crystals into contact with a melt containing an alkali metal and a Group III metal, and dissolving nitrogen in the melt to grow a Group III nitride semiconductor on the plural seed crystals, the plural seed crystals are disposed inside a disposition region which has a predetermined plane pattern, and the disposition region has: a hexagonal region having a hexagonal shape; and at least two enlarged regions as defined herein.