Vertical III-Nitride LED Structure on SOI Substrate
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Solution Overview
Problem
Current methods for forming high-brightness light emitting diodes (LEDs) face challenges such as high costs and non-uniformity due to the use of expensive sapphire or SiC substrates, limited growth potential, and heat dissipation issues, as well as lower internal quantum efficiency due to lattice and thermal mismatch with silicon substrates.
Innovation Solution
A method involving the formation of a III-nitride based light emitting diode structure on a silicon-on-insulator (SOI) substrate, followed by layer transfer to a metal-based substrate, using techniques like mechanical removal, etching, and electroplating, with the incorporation of seed layers, reflective mirror layers, and photonic crystal structures to enhance light emission and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If sapphire or SiC substrates are used for GaN-based LED growth, then high brightness light emission is achieved, but manufacturing cost increases and substrate size is limited to 6 inches
Solution Approach 1:
The patent introduces a sacrificial SiO2 layer as an intermediary between the GaN LED structure and the final substrate. This layer enables the LED to be grown on inexpensive silicon substrates, then transferred to conducting substrates through chemical lift-off, eliminating the need for expensive sapphire or SiC substrates while maintaining large substrate size capability
Solution Approach 2:
The patent uses disposable silicon substrates with SiO2 sacrificial layers as temporary growth platforms. These inexpensive substrates serve their purpose during LED growth and are then completely removed through chemical lift-off, allowing the LED structure to be transferred to the final conducting substrate without the cost of permanent expensive substrates
2Ease of manufacture
If high power lasers are used for laser lift-off of sapphire/SiC substrates, then substrate removal is achieved, but process complexity increases and yield uniformity decreases
Solution Approach 1:
The patent replaces the mechanical/high-energy laser lift-off process with a chemical lift-off process using selective etchants. The etchants chemically dissolve the SiO2 sacrificial layer at lower temperatures, eliminating the need for high power lasers and associated complexity while improving yield uniformity across large wafers
Solution Approach 2:
The patent changes the removal mechanism from high-energy laser ablation to low-temperature chemical etching. This parameter change allows substrate removal at temperatures below 100°C using selective etchants, simplifying the process and improving control while maintaining effective substrate removal capability
3Ease of manufacture
If silicon substrates are used for LED growth, then manufacturing cost decreases and substrate size can be enlarged, but internal quantum efficiency decreases due to lattice and thermal mismatch
Solution Approach 1:
The patent introduces a SiO2 sacrificial layer as an intermediary that decouples the LED growth process from the final substrate. This allows growth on silicon with its cost and size advantages while the final conducting substrate provides the thermal and electrical properties needed for high efficiency operation, effectively separating the conflicting requirements
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 enables the production of high-quality, high-power LEDs with improved light emission efficiency and thermal management, bypassing costly substrate transfer methods and achieving comparable internal quantum efficiency to sapphire or SiC-based LEDs, while allowing for larger substrate sizes and cost-effective manufacturing.
Implementation Method 1
removing the SOI substrate by a layer transfer process such that the metal-based electrode structure functions as a metal-based substrate of the light emitting structure
Implementation Method 2
incorporation of seed layers, reflective mirror layers, and photonic crystal structures to enhance light emission
Implementation Method 3
incorporation of seed layers, reflective mirror layers, and photonic crystal structures to enhance light emission
Implementation Method 4
allowing for larger substrate sizes and cost-effective manufacturing
Data Source
AI summary
A method of forming a vertical III-nitride based light emitting diode structure 5 and a vertical III-nitride based light emitting diode structure can be provided. The method comprises forming a III-nitride based light emitting structure on a silicon-oninsulator (SOI) substrate; forming a metal-based electrode structure on the III-nitride based light emitting structure; and removing the SOI substrate by a layer transfer process such that the metal-based electrode structure functions as a metal-based 10 substrate of the light emitting structure.