Nitride Semiconductor P-Electrode Oxidation Prevention
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Solution Overview
Problem
Conventional nitride semiconductor devices experience increased resistance and instability due to oxidation of the p electrode during heat treatment, leading to variations in electrical characteristics and heat generation, which affects the stability and power output of devices like laser diodes.
Innovation Solution
A nitride semiconductor device is manufactured with a p electrode composed of a first palladium film, a tantalum film, and a second palladium film acting as an antioxidant, preventing oxidation of the tantalum film, thereby reducing contact resistance and ensuring low resistance between the p electrode and the pad electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed in an atmosphere containing oxygen after forming a p electrode, then the p electrode is heat-treated to improve electrical characteristics, but the p electrode undergoes oxidation forming an oxide film that increases resistance and causes contact failure
Solution Approach 1:
A protective film comprising a first Pd film and a first Ta film is introduced as an intermediary between the p-type contact layer and the external environment. This protective film acts as a barrier that prevents oxygen from reaching and oxidizing the p electrode during heat treatment, while still allowing the heat treatment process to proceed and improve electrical characteristics of the underlying semiconductor structure
Solution Approach 2:
The protective film creates an inert environment for the p electrode by physically isolating it from the oxygen-containing atmosphere during heat treatment. The Pd and Ta materials in the protective film are selected for their resistance to oxidation, effectively creating a localized inert zone that protects the sensitive p electrode from harmful oxidative effects
2Ease of manufacture
If a pad electrode is formed on the p electrode with an oxide film present, then the pad electrode can be formed on the heat-treated surface, but the oxide film acts as an insulator causing failure in contact between electrodes
Solution Approach 1:
The protective film serves as an intermediary barrier that prevents oxide formation on the p electrode surface during heat treatment. By blocking oxygen access, the protective film ensures that when the pad electrode is subsequently formed, it contacts a clean, non-oxidized p electrode surface, establishing reliable electrical connectivity without insulating oxide layers
Solution Approach 2:
The protective film is formed beforehand (in advance) to prevent oxidation before it can occur. This preliminary protective action ensures that the p electrode surface remains oxidation-free during the entire heat treatment process and subsequent pad electrode formation, guaranteeing good contact connectivity from the outset
3Device complexity
If the p electrode is heat-treated without protection, then the manufacturing process is simplified, but resistance between electrodes increases due to oxidation
Solution Approach 1:
The protective film comprising Pd and Ta layers is introduced as a mediator that prevents direct interaction between the p electrode and oxygen. This intermediary layer maintains low contact resistance by preventing oxidation, while the overall device complexity increases only modestly due to the addition of this necessary protective structure
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 effectively reduces operating voltage and heat generation, enabling high-power and stable operation of nitride semiconductor devices by preventing oxidation and maintaining low resistance between electrodes.
Implementation Method 1
a second Pd film is formed, as an antioxidant film that prevents oxidation of the Ta film, on an entire upper surface of the Ta film
Data Source
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, 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 is formed on the entire upper surface of the Ta film which forms part of the p electrode, and serves as an antioxidant film that prevents oxidation of the Ta film. Preventing oxidation of the Ta film, the second Pd film can reduce the resistance that may exist 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 p electrode with low resistance.