GaN Seed Crystal Laser Interface Modification

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Solution Overview

Problem

Existing methods for growing gallium nitride crystals on seed crystal substrates often result in cracks, reduced production yield, and bowing issues due to incomplete separation from the supporting body, with voids forming during thermal decomposition and laser irradiation.

Innovation Solution

A method involving the irradiation of laser light from the side of the supporting body to create an altered portion with dislocation defects or an amorphous layer along the interface between the supporting body and the seed crystal layer, preventing voids and enabling easier separation of the gallium nitride crystal without cracks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a seed crystal film is formed on a sapphire substrate and a thick film of gallium nitride is grown, then a thick gallium nitride layer can be obtained, but parts remain adhered to the supporting body resulting in reduced production yield

Engineering Contradiction:

Improvethickness of gallium nitride layerVSAvoidproduction yield

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

Laser irradiation is performed on the interface between the sapphire substrate and seed crystal film before growing the thick gallium nitride layer. This preliminary action creates an altered portion that prevents adhesion, ensuring complete separation later while maintaining high production yield and allowing growth of thick gallium nitride layers

Inventive Principle:

Principle #10Preliminary action

2Area of stationary object

If the area of the supporting body is increased, then larger gallium nitride layers can be produced, but cracks and bowing increase

Engineering Contradiction:

Improvearea of supporting bodyVSAvoidcracks and bowing

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

Laser irradiation is applied to the entire interface area between the sapphire substrate and seed crystal film before growing the gallium nitride layer. This creates an altered portion across the whole interface that prevents adhesion, enabling complete separation of large-area gallium nitride layers without cracks or bowing

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Laser irradiation changes the physical and chemical parameters of the interface region, creating an altered portion with different properties that prevents adhesion. This parameter change allows large-area gallium nitride layers to be produced without cracks or bowing

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If laser irradiation is applied to thermal decompose gallium nitride in void regions, then voids can be filled, but the seed crystal layer may melt back into the melt causing disappearance

Engineering Contradiction:

Improvequality of gallium nitride crystalVSAvoidstability of seed crystal layer

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

Laser irradiation is performed on the interface between the sapphire substrate and seed crystal film before growing the gallium nitride layer to create an altered portion. This preliminary action prevents void formation in the first place, eliminating the need for subsequent laser irradiation that could cause seed crystal melting

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The laser irradiation is applied at a stage and in a manner that converts the potential harm of laser heating into a beneficial effect. By irradiating the interface before gallium nitride growth rather than irradiating void regions after growth, the laser energy creates adhesion prevention without causing seed crystal melting or nitrogen saturation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly reduces cracks and improves the production yield by allowing for the growth of high-quality, free-standing gallium nitride substrates with reduced bowing, facilitating their separation from the supporting body.

Implementation Method 1

irradiating a laser light from a side of the supporting body to provide an altered portion comprising the nitride of the group 13 element along an interface between the supporting body and the seed crystal layer

Methodology Applied

Scientific EffectLaser irradiation: Laser

Data Source

PatentUS10192738B2Methods of producing seed crystal substrates and group 13 element nitride crystals, and seed crystal substrates

Publication Date: 2019.01.29 NGK INSULATORS LTD

AI summary

A seed crystal layer is provided on a supporting body. A laser light is irradiated from a side of the supporting body to provide an altered portion along an interface between the supporting body and seed crystal layer. The altered layer is composed of a nitride of a group 13 element and has a portion into which dislocation defects are introduced or an amorphous portion.