Light Emitting Device Columnar Parts Concavo-Convex Electrode

Solution Overview

Problem

Existing semiconductor light emitting devices with nano-column structures face challenges in ensuring reliable electrical contacting due to microscopic concavo-convex shapes on the n-type electrode, which affect the connection reliability with bonding wires or anisotropic conductive films.

Innovation Solution

A light emitting device configuration with a substrate, a laminated structure of columnar parts, and electrically-conductive layers, where an insulating layer is applied to the concavo-convex shapes on the first electrically-conductive layer, and an electrode layer is formed to cover these shapes, enhancing electrical and mechanical connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the area where nano-columns are formed is etched to reach the n-type GaN layer and an n-type electrode is provided, then the electrode can be formed on the etched area, but the concavo-convex shapes remain on the electrode surface making it difficult to ensure electrical connection reliability

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidsurface shape of electrode

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent applies local quality by creating a planarized region on the electrode surface through selective etching. Specifically, a flat surface portion is formed on the n-type electrode by removing the concavo-convex shapes in a localized area, while the rest of the electrode maintains its original structure. This allows bonding wires or anisotropic conductive films to be reliably connected to the planarized region, solving the electrical connection reliability issue caused by the overall concavo-convex surface shape.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If dry etching is used to etch the area where nano-columns are formed, then the etching process can be performed, but microscopic concavo-convex shapes are traced on the electrode surface

Engineering Contradiction:

Improveetching processabilityVSAvoidelectrical connection reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies segmentation by dividing the electrode surface into two functional regions: a planarized region where the concavo-convex shapes are removed through selective etching to ensure reliable electrical connection, and a non-planarized region that maintains the original concavo-convex structure. This segmentation allows the electrode to simultaneously achieve good electrical connection reliability at the planarized region while preserving the overall etched structure for manufacturing purposes.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the electrode surface has concavo-convex shapes, then the electrode can be formed following the nano-column structure, but it becomes difficult to connect bonding wires or anisotropic conductive films reliably

Engineering Contradiction:

Improveelectrode structure adaptabilityVSAvoidelectrical connection reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by creating a planarized region on the electrode surface through selective etching. Specifically, a flat surface portion is formed on the n-type electrode by removing the concavo-convex shapes in a localized area, while the rest of the electrode maintains its original structure. This allows bonding wires or anisotropic conductive films to be reliably connected to the planarized region, solving the electrical connection reliability issue caused by the overall concavo-convex surface shape.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11624973B2Light emitting device having columnar parts surrounded by concavo-convex shapes and projector

Publication Date: 2023.04.11 SEIKO EPSON CORP

AI summary

A light emitting device includes a substrate, a first semiconductor layer provided to the substrate, a laminated structure disposed at an opposite side to the substrate of the first semiconductor layer, and including a plurality of columnar parts, a first electrically-conductive layer as a surface layer at laminated structure side in the first semiconductor layer, and a second electrically-conductive layer opposed to the first electrically-conductive layer via the laminated structure, wherein the columnar part includes a light emitting layer configured to emit light, a second semiconductor layer which is disposed between the light emitting layer and the first electrically-conductive layer, and a third semiconductor layer disposed between the light emitting layer and the second electrically-conductive layer, concavo-convex shapes are formed on a surface of the first electrically-conductive layer, an insulating layer is disposed on the first electrically-conductive layer, and electrode layers are disposed so as to cover an area where the insulating layer is disposed, and some of the concavo-convex shapes.