Nitride Semiconductor P-Electrode Oxidation Prevention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional nitride semiconductor devices experience increased resistance and instability due to oxidation of the p electrode, leading to higher operating voltage and heat generation, which affects the stability and yield of nitride semiconductor devices like laser diodes.

Innovation Solution

A nitride semiconductor device is manufactured with a p electrode composed of a palladium (Pd) film, a tantalum (Ta) film, and an antioxidant film to prevent oxidation, reducing resistance and ensuring stable operation. The method involves forming the Pd and Ta films on a p-type contact layer, followed by an antioxidant film on the Ta film to inhibit oxidation, and thermally processing the p electrode in an oxygen-containing atmosphere.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heat treatment is performed in an oxygen-containing atmosphere after forming a p electrode, then the p electrode is thermally processed to improve contact, but oxidation of the p electrode occurs forming an oxide film that increases resistance

Engineering Contradiction:

Improvecontact stabilityVSAvoidoxidation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An antioxidant film is introduced as an intermediary layer between the p electrode and the oxygen-containing atmosphere during heat treatment. This antioxidant film acts as a mediator that prevents direct contact between oxygen and the p electrode, thereby preventing oxidation while allowing the heat treatment to proceed and improve contact properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful effect of oxygen (oxidation) into a beneficial protective mechanism by applying an antioxidant film. The antioxidant film is specifically designed to react with or resist oxygen, thereby protecting the p electrode from oxidation during the necessary thermal processing steps.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of manufacture

If a pad electrode is formed on an oxidized p electrode with an oxide film, then the pad electrode structure is completed, but the oxide film acts as an insulator causing contact failure between electrodes

Engineering Contradiction:

Improvepad electrode formationVSAvoidelectrode contact

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The antioxidant film is applied in advance before the heat treatment step that would otherwise cause oxidation. This preliminary protective action ensures that when the pad electrode is subsequently formed, the underlying p electrode remains free of oxide films, guaranteeing good electrical contact while allowing normal manufacturing progression.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If the p electrode is formed without antioxidant protection, then the manufacturing process is simpler, but resistance increases due to oxidation during heat treatment

Engineering Contradiction:

Improveelectrode structureVSAvoidoxidation resistance

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The p electrode structure is enhanced by combining the conductive p electrode material with an antioxidant film layer, creating a composite structure. This composite approach maintains the electrical functionality of the p electrode while adding oxidation resistance through the antioxidant film, achieving both simplicity and protection.

Inventive Principle:

Principle #40Composite materials

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 reduces the operating voltage and heat generation, enabling high-power and stable operation of nitride semiconductor devices by maintaining low resistance between the p electrode and pad electrode.

Implementation Method 1

The antioxidant film is formed on the entire upper surface of the Ta film to prevent oxidation of the Ta film

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Implementation Method 2

In the heat-treatment step, the p electrode formed is thermally processed

Methodology Applied

Scientific EffectThermal processing: Heat Treatment

Data Source

PatentUS7939943B2Nitride semiconductor device including an electrode in ohmic contact with a P-type nitride semiconductor contact layer

Publication Date: 2011.05.10 MITSUBISHI ELECTRIC CORP

AI summary

A nitride semiconductor device with a p electrode having no resistance between itself and other electrodes, and a method of manufacturing the same are provided. A p electrode is formed of a first Pd film, a Ta film, and a second Pd film, which is an antioxidant film for preventing oxidation of the Ta film, and on a p-type contact layer of a nitride semiconductor. On the second Pd film, a pad electrode is formed. The second Pd film as an antioxidant film is formed on the entire upper surface of the Ta film which forms the p electrode, to prevent oxidation of the Ta film. This inhibits the resistance between the p electrode and the pad electrode, thereby preventing a failure in contact between the p electrode and the pad electrode and providing the low-resistance p electrode.