Gallium Aluminum Oxide Buffer Layer for Nitride Semiconductor Delamination
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Solution Overview
Problem
The manufacturing of vertical type nitride semiconductor light emitting devices faces challenges due to delamination issues caused by irregular etching of the gallium oxide substrate interface and thermal expansion coefficient differences, leading to poor adhesive strength and reliability.
Innovation Solution
A nitride semiconductor light emitting device is fabricated using a gallium aluminum oxide layer over a gallium oxide substrate, enhancing interfacial adhesion through stronger bond strengths between gallium and oxygen compared to aluminum and oxygen, and between gallium and nitrogen compared to aluminum and nitrogen, preventing delamination and ensuring a high-quality nitride semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a gallium oxide substrate is used for vertical type nitride semiconductor light emitting devices, then the manufacturing process can avoid substrate separation, but the nitride semiconductor layer delaminates from the substrate due to irregular etching and thermal expansion differences
Solution Approach 1:
An aluminum oxide layer is introduced as an intermediary between the gallium oxide substrate and the nitride semiconductor layer. This intermediate layer acts as a buffer that reduces the thermal expansion coefficient mismatch and prevents direct contact between the gallium oxide substrate and nitride layer, thereby eliminating delamination while maintaining manufacturing simplicity
Solution Approach 2:
The thermal expansion coefficient parameter is modified by introducing the aluminum oxide intermediate layer, which has a thermal expansion coefficient between that of gallium oxide and nitride semiconductor. This parameter adjustment resolves the thermal stress issue that causes delamination during cooling and heat treatment processes
2Manufacturing precision
If the nitride semiconductor layer is grown at high temperature with ammonia and hydrogen gas, then the nitride layer can be formed, but the gallium oxide substrate interface is irregularly etched by hydrogen gas, degrading adhesive strength
Solution Approach 1:
The aluminum oxide layer serves as a protective intermediary that shields the gallium oxide substrate interface from hydrogen gas etching during nitride semiconductor layer growth. This intermediate barrier allows high-temperature ammonia and hydrogen gas processing to form quality nitride layers without directly exposing the gallium oxide substrate to harmful etching
Solution Approach 2:
The aluminum oxide layer is formed in advance before nitride semiconductor layer growth, creating a protective interface that prevents subsequent etching damage. This preliminary protective action ensures the substrate interface remains intact during the high-temperature nitride layer formation process
3Productivity
If the nitride semiconductor layer is cooled after growth or heat treatment is performed, then the light emitting device can be manufactured, but delamination occurs at the interface due to stress from thermal expansion coefficient differences
Solution Approach 1:
The aluminum oxide intermediate layer is specifically chosen because its thermal expansion coefficient lies between those of gallium oxide and nitride semiconductor. This thermal expansion matching reduces stress during cooling and heat treatment, preventing delamination while allowing normal manufacturing processes to proceed
Solution Approach 2:
The aluminum oxide layer acts as a thermal expansion buffer that mediates the stress between the gallium oxide substrate and nitride semiconductor layer during temperature changes. This intermediate structure absorbs thermal stress, maintaining interface integrity throughout the manufacturing process
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 approach results in a light emitting device with superior reliability and performance by enhancing the interfacial adhesion between the gallium oxide substrate and the nitride semiconductor layer, preventing delamination and enabling high-quality nitride semiconductor growth.
Implementation Method 1
enhancing interfacial adhesion through stronger bond strengths between gallium and oxygen compared to aluminum and oxygen
Implementation Method 2
enhancing interfacial adhesion through stronger bond strengths between gallium and nitrogen compared to aluminum and nitrogen
Implementation Method 3
A light emitting device (LED) includes a p-n junction diode having a characteristic of converting electric energy into light energy
Implementation Method 4
the gallium oxide substrate has a thermal expansion coefficient different from that of the nitride semiconductor layer. Accordingly, when the nitride semiconductor layer is cooled after the nitride semiconductor layer has been grown, or when a heat treatment process is performed in order to manufacture the light emitting device, the delamination may be caused at the interface between the gallium oxide substrate and the nitride semiconductor layer due to the stress caused by the difference in the thermal expansion coefficient
Data Source
AI summary
Disclosed is a method for fabricating a light emitting device. The method includes forming an oxide including gallium aluminum over a gallium oxide substrate, forming a nitride including gallium aluminum over the oxide including gallium aluminum and forming a light emitting structure over the nitride including gallium aluminum.