Semiconductor Light-Emitting Element Electrode Adhesion and Voltage Reduction

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Solution Overview

Problem

Semiconductor light-emitting elements of the waveguide ridge type face issues with high operating voltage due to small contact areas between electrodes and waveguide ridges, and p-side electrodes are prone to peeling off due to poor adhesiveness with insulating films.

Innovation Solution

A semiconductor light-emitting device with a p-side electrode contacting the entire surface of the waveguide ridge and an insulator film coating the side faces and end portions of the electrode, but not the center portion, along with a manufacturing method involving an image reversal resist to pattern the electrode and form the waveguide ridge and insulator film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the p-side electrode is formed after forming an insulating film for coating the side faces of the waveguide ridge, then the insulating film can be formed continuously, but the p-side electrode is easily peeled off due to poor adhesiveness with the SiO2 film

Engineering Contradiction:

Improvecontinuous insulating film formationVSAvoidelectrode adhesion

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The p-side electrode is formed preliminarily before forming the insulating film. This preliminary action allows the electrode to be formed on the semiconductor layer where it has good adhesion, and then the insulating film is formed over the electrode and waveguide ridge, solving both the adhesion problem and enabling continuous insulating film formation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conventional sequence is inverted: instead of forming the insulating film first and then the electrode, the electrode is formed first and then the insulating film is formed over it. This inversion resolves the adhesion issue while maintaining the benefit of continuous insulating film formation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Manufacturing precision

If an opening is formed in the insulating film on the top of the waveguide ridge by a lift-off process, then the insulating film can be removed from the opening area, but the insulating film is left on both ends of the top of the waveguide ridge, resulting in small contact areas between the electrode and waveguide ridge

Engineering Contradiction:

Improveinsulating film patterningVSAvoidelectrode contact area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The p-side electrode is formed preliminarily before forming the insulating film, covering the entire top surface of the waveguide ridge. This preliminary electrode formation ensures maximum contact area, and the subsequent insulating film formation and lift-off process do not reduce this contact area.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The insulating film is segmented through the lift-off process, removing it only from the opening area while leaving it on the side faces and end portions. This segmentation allows the electrode to maintain full contact with the waveguide ridge top while the insulating film provides coverage where needed.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7879684B2Method for manufacturing semiconductor light-emitting element

Publication Date: 2011.02.01 MITSUBISHI ELECTRIC CORP

AI summary

A semiconductor light-emitting device comprises: a semiconductor substrate; a semiconductor layer structure on the semiconductor substrate, including an active layer and a waveguide ridge; an electrode in contact with all of a top surface of the waveguide ridge; and an insulating film coating side faces of the waveguide ridge, side faces of the electrode, and ends, but not a center portion, of an upper face of the electrode.