Nitride Multilayer Buffer for Silicon Substrate Light Emitting Devices

Solution Overview

Problem

The high manufacturing cost and crystal defects associated with using sapphire or GaN substrates for semiconductor light emitting devices, due to lattice mismatch and thermal expansion coefficient differences, limit the industrial applicability and efficiency of nitride semiconductor-based light emitting diodes.

Innovation Solution

A method involving epitaxial growth of a nitride multilayer film on a silicon or silicon nitride substrate, with alternating layers of aluminum nitride and gallium nitride, which serves as a buffer to suppress silicon diffusion and lattice strain, and is used as an antireflection layer to enhance light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If sapphire substrate is used for crystal growth, then crystal growth stability is improved, but manufacturing cost increases and crystal defects occur due to lattice mismatch

Engineering Contradiction:

Improvecrystal growth stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent uses a silicon substrate instead of an expensive sapphire substrate as a temporary platform for epitaxial growth. The silicon substrate serves its purpose during the growth process and is subsequently removed, allowing the nitride semiconductor layer to be transferred to a final substrate. This disposable approach to the initial substrate dramatically reduces manufacturing costs while still enabling high-quality crystal growth.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces a buffer layer structure as an intermediary between the silicon substrate and the nitride semiconductor layer. This buffer layer mediates the lattice mismatch and thermal expansion differences, enabling successful epitaxial growth on silicon without directly encountering the substrate's defects. The buffer layer acts as a transition zone that facilitates the growth process on a low-cost substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If sapphire substrate is used for crystal growth, then crystal growth stability is improved, but crystal defects increase due to lattice mismatch and thermal expansion coefficient difference

Engineering Contradiction:

Improvecrystal growth stabilityVSAvoidcrystal quality

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent introduces a buffer layer structure as an intermediary between the silicon substrate and the nitride semiconductor layer. This buffer layer mediates the lattice mismatch and thermal expansion differences, enabling successful epitaxial growth on silicon without directly encountering the substrate's defects. The buffer layer acts as a transition zone that facilitates the growth process on a low-cost substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the growth parameters and layer structure by using multiple buffer layers with different compositions and thicknesses. By controlling the thickness, composition, and structure of these buffer layers, the patent optimizes the transition from silicon substrate to nitride semiconductor, minimizing defect formation while maintaining crystal growth stability.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If GaN substrate is used, then material matching is improved, but manufacturing cost increases and industrial applicability decreases

Engineering Contradiction:

Improvematerial matchingVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses a silicon substrate instead of an expensive GaN substrate as a temporary platform for epitaxial growth. The silicon substrate serves its purpose during the growth process and is subsequently removed, allowing the nitride semiconductor layer to be transferred to a final substrate. This disposable approach to the initial substrate dramatically reduces manufacturing costs while still enabling high-quality crystal growth.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces a buffer layer structure as an intermediary between the silicon substrate and the nitride semiconductor layer. This buffer layer mediates the lattice mismatch and thermal expansion differences, enabling successful epitaxial growth on silicon without directly encountering the substrate's defects. The buffer layer acts as a transition zone that facilitates the growth process on a low-cost substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If large-diameter sapphire substrate is used, then production capacity is improved, but manufacturing cost increases

Engineering Contradiction:

Improveproduction capacityVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent uses a silicon substrate instead of an expensive sapphire substrate as a temporary platform for epitaxial growth. The silicon substrate serves its purpose during the growth process and is subsequently removed, allowing the nitride semiconductor layer to be transferred to a final substrate. This disposable approach to the initial substrate dramatically reduces manufacturing costs while still enabling high-quality crystal growth.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 reduces manufacturing costs by using low-cost silicon substrates, improves crystallinity, and increases light extraction efficiency by up to 1.2 times compared to traditional methods, while maintaining high optical quality and reducing substrate-related defects.

Implementation Method 1

forming a light emitting layer including a nitride semiconductor on top of the nitride multilayer film, joining a laminate including the substrate for crystal growth, the nitride multilayer film and the light emitting layer

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

The nitride multilayer film includes a first layer including a first nitride semiconductor containing aluminum, a second layer including a second nitride semiconductor having a refractive index different from the refractive index of the first nitride semiconductor

Methodology Applied

Scientific EffectLattice matching:

Implementation Method 3

the nitride multilayer film includes a first layer including a first nitride semiconductor containing aluminum, a second layer including a second nitride semiconductor having a refractive index different from the refractive index of the first nitride semiconductor

Methodology Applied

Scientific EffectAntireflection: Anti-Reflective Coating

Implementation Method 4

performing epitaxial growth of a nitride multilayer film on top of a substrate for crystal growth including silicon or silicon nitride

Methodology Applied

Scientific EffectEpitaxy: Epitaxy

Data Source

PatentUS9312444B2Semiconductor light emitting device and manufacturing method thereof

Publication Date: 2016.04.12 SEOUL SEMICONDUCTOR

AI summary

A semiconductor light emitting device includes a supporting substrate, a light emitting layer including a nitride semiconductor, and a nitride multilayer film. The nitride multilayer film includes a first layer including a first nitride semiconductor containing aluminum nitride, a second layer including a second nitride semiconductor containing gallium nitride, and a third layer including the first nitride semiconductor containing aluminum nitride.