Light-Emitting Element Assembly with Recessed Substrate

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Solution Overview

Problem

Current surface-emitting laser elements face challenges with heat radiation due to low thermal conductivity in mirror layers, leading to decreased emission efficiency, and the complex and costly process of dividing wafers into chips for mounting on sub-mounts, which limits design freedom and heat dissipation.

Innovation Solution

A light-emitting element assembly with a support substrate having a recessed portion and a conductive material layer, where the mesa structure of the light-emitting element is placed to enable partial contact between the conductive material layer and the second electrode, allowing efficient heat radiation and simplifying the assembly process, while emitting light from the second surface of the compound semiconductor layer without substrate absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If mirror layers are used to enclose light for laser oscillation, then light emission efficiency is improved, but thermal conductivity is insufficient leading to poor heat radiation

Engineering Contradiction:

Improvelight emission efficiencyVSAvoidheat radiation

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The device is divided into separate functional components: the VCSEL chip with DBR mirror layers for light generation, and a separate heat sink substrate for heat dissipation. This segmentation allows each component to optimize its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A conductive adhesive layer serves as an intermediary between the VCSEL chip and heat sink substrate, providing both mechanical bonding and thermal conduction pathways. This mediator enables efficient heat transfer from the chip to the heat sink while maintaining structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If wafer is divided into individual chips and mounted on sub-mount, then heat radiation is improved, but assembly complexity and cost increase

Engineering Contradiction:

Improveheat radiationVSAvoidassembly process

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The heat sink substrate integrates multiple functions into a single component: it provides mechanical support, thermal management, and electrical connection pathways. This merging eliminates the need for separate sub-mount structures and simplifies the overall assembly process.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The heat sink substrate serves multiple purposes simultaneously: it acts as a heat dissipation path, a mechanical support structure, and an electrical connection medium through the conductive adhesive layer. This multi-functionality reduces the number of components needed.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Use of energy by moving object

If light is emitted through substrate, then emission efficiency is reduced due to substrate absorption, but design freedom is maintained

Engineering Contradiction:

Improveemission efficiencyVSAvoiddesign freedom

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The substrate is removed from the light emission path by mounting the VCSEL chip on the heat sink substrate with the light-emitting surface facing outward. This extraction eliminates substrate absorption losses while the heat sink substrate provides the necessary mechanical and thermal support.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration enhances heat dissipation, prevents emission efficiency decrease, simplifies assembly, and increases design freedom by allowing efficient light emission without substrate absorption, thereby extending the operating temperature range and reducing manufacturing complexity.

Implementation Method 1

a conductive material layer formed over the first surface and the inner surface of the recessed portion... effectively radiating heat generated in the light-emitting portion

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

an active layer having a multiquantum well structure is provided in a cavity held between two mirror layers... light emitted from the active layer (light-emitting portion) due to current injection

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8372670B2Light-emitting element assembly and method for manufacturing the same

Publication Date: 2013.02.12 SONY GROUP CORP

AI summary

A method for making a light-emitting element assembly including a support substrate having a first surface, a second surface facing the first surface, a recessed portion, and a conductive material layer formed over the first surface and the inner surface of the recessed portion, and a light-emitting element. The light-emitting element has a laminated structure including a first compound semiconductor layer, a light-emitting portion, and a second compound semiconductor layer, at least the second compound semiconductor layer and the light-emitting portion constituting a mesa structure. The light-emitting element further includes an insulating layer formed, a second electrode, and a first electrode. The mesa structure is placed in the recessed portion so that the conductive material layer and the second electrode are in at least partial contact with each other, and light emitted from the light-emitting portion is emitted from the second surface side of the first compound semiconductor layer.