Light-Emitting Device with Segmented Semiconductor Layer

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Solution Overview

Problem

In light-emitting devices with a window layer-cum-support substrate and a light-emitting portion, the high Al content in the clad layer leads to a higher etching rate during surface roughening, making it difficult to achieve a desired roughened surface without compromising the mechanical strength of the pad electrode, which increases the risk of chip cracks during wire bonding.

Innovation Solution

A light-emitting device structure with a first semiconductor layer comprising two layers: a low-Al-content roughened-side layer and a high-Al-content active-layer-side layer, where the roughened-side layer has a lower Al content than the active-layer-side layer, allowing for reduced etching depth and preventing chip cracks during wire bonding, while maintaining the effect of trapping carriers in the clad layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the clad layer has high Al content to effectively trap carriers, then the carrier trapping effect is improved, but the etching rate increases making it difficult to achieve desired surface roughening without compromising mechanical strength

Engineering Contradiction:

Improvecarrier trapping effectVSAvoidsurface roughening process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The first semiconductor layer is divided into two distinct layers: a lower layer with high Al content (0.6≤x≤1) for carrier trapping, and an upper layer with low Al content (0≤x<0.6) for surface roughening. This segmentation allows each layer to independently fulfill its specific function without interfering with the other, resolving the contradiction between carrier trapping effectiveness and etching controllability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the first semiconductor layer are given different Al compositions tailored to their specific functions: the lower layer near the active layer has high Al content optimized for carrier confinement, while the upper layer near the surface has low Al content optimized for controlled etching and roughening. This local quality differentiation enables simultaneous optimization of both carrier trapping and surface treatment processes

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If deep etching is performed to achieve desired roughened surface shape, then the surface roughening is improved, but the mechanical strength of pad electrode decreases increasing risk of chip cracks

Engineering Contradiction:

Improvesurface roughened shapeVSAvoidmechanical strength of pad electrode

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The first semiconductor layer is segmented into two layers with different Al contents, where the upper low-Al layer serves as a sacrificial etching layer that can be deeply etched to create the desired roughened surface shape without compromising the mechanical strength of the underlying structure and pad electrode

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The upper low-Al-content layer acts as an intermediary sacrificial layer between the etching process and the pad electrode. This layer absorbs the etching action, allowing deep etching to achieve the desired surface roughness while protecting the pad electrode from direct etching damage that would compromise its mechanical strength

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution reduces the etching depth required for a desired roughened shape, inhibits chip cracks during wire bonding, and maintains the carrier trapping effect in the clad layer, enhancing the manufacturing efficiency and reliability of the light-emitting device.

Implementation Method 1

a first surface roughening treatment step of roughening a surface of the first semiconductor layer; and a second surface roughening treatment step of roughening a surface and a side surface of the window layer-cum-support substrate

Methodology Applied

Scientific EffectSurface roughening:

Implementation Method 2

an insulator top coat at least partially coating a surface of the first semiconductor layer and a side surface of the light-emitting portion

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 3

the roughened-side layer is formed of a material having a lower Al content than that of the active-layer-side layer

Methodology Applied

Scientific EffectSelective etching:

Data Source

PatentUS10388831B2Light-emitting device and method for manufacturing light-emitting device

Publication Date: 2019.08.20 SHIN ETSU HANDOTAI CO LTD

AI summary

A light-emitting device including a window layer-cum-support substrate, a light-emitting portion provided on the window layer-cum-support substrate and including a second semiconductor layer of a second conductivity type, an active layer, and first semiconductor layer of a first conductivity type in stated order, a first ohmic electrode provided on the first semiconductor layer, and insulator top coat at least partially coating the first semiconductor layer surface and light-emitting portion side surface, wherein the first semiconductor layer surface and surface of the window layer-cum-support substrate are roughened, and the first semiconductor layer includes at least two layers of an active-layer-side layer and roughened-side layer, and roughened-side layer is formed of material having lower Al content than the active-layer-side layer. This light-emitting device can reduce etching depth required to obtain desired roughened shape and inhibit occurrence of chip cracks during wire bonding, while keeping effect of trapping carriers in the clad layer.