GaN Vertical LED Fabrication via Laser Substrate Extraction
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Solution Overview
Problem
Conventional methods for fabricating nitride-based semiconductor devices, such as LEDs, face challenges in achieving high yield and performance, particularly in terms of brightness and thermal conductivity, due to the use of non-conductive substrates like sapphire, which limits heat dissipation and device efficiency.
Innovation Solution
A method involving a wafer assembly with n-doped and p-doped layers and a multiple quantum well layer, where laser cutting is used to define vertical light-emitting diode (VLED) devices without completely cutting through the substrate, combined with techniques like dry etching and wet etching, to enhance device separation and reduce substrate damage, while using non-conductive materials to absorb potential destructive forces during separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional methods use non-conductive sapphire substrates for fabricating nitride-based semiconductor devices, then device fabrication is enabled, but heat dissipation is limited and device efficiency decreases
Solution Approach 1:
The patent extracts and removes the non-conductive sapphire substrate from the final device structure through selective laser cutting and etching processes. The substrate is used temporarily during fabrication to enable high-yield production of multiple devices, then completely removed to allow the devices to be mounted on heat-conductive substrates for optimal thermal management and efficiency.
Solution Approach 2:
The patent segments the fabrication process into two distinct phases: first, fabricating multiple devices simultaneously on a sapphire substrate in a wafer assembly; second, separating individual devices from the substrate through laser cutting and etching. This segmentation enables the substrate to serve its temporary purpose without compromising the final thermal performance of the devices.
2Manufacturing precision
If laser cutting is used to define semiconductor devices in the wafer assembly, then device separation is achieved, but substrate damage may occur
Solution Approach 1:
The patent applies partial action by using laser cutting to define device patterns without completely cutting through the substrate. The laser creates precise trenches and defines device boundaries while leaving the substrate intact, enabling subsequent separation steps without compromising substrate integrity.
Solution Approach 2:
The patent introduces an intermediary etching process between laser cutting and final device separation. The etching process selectively removes material in the laser-defined regions, facilitating clean device separation while the intact substrate continues to provide mechanical support and protection during the separation 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 improves the yield and performance of nitride-based semiconductor devices by enhancing brightness and thermal conductivity, allowing for better heat dissipation and reducing damage during substrate separation, thus addressing the limitations of conventional fabrication methods.
Implementation Method 1
applying a laser to cut through at least the deposited layers without cutting completely through the substrate and define one or more semiconductor devices in the wafer assembly
Data Source
AI summary
Techniques for fabricating metal devices, such as vertical light-emitting diode (VLED) devices, power devices, laser diodes, and vertical cavity surface emitting laser devices, are provided. Devices produced accordingly may benefit from greater yields and enhanced performance over conventional metal devices, such as higher brightness of the light-emitting diode and increased thermal conductivity. Moreover, the invention discloses techniques in the fabrication arts that are applicable to GaN-based electronic devices in cases where there is a high heat dissipation rate of the metal devices that have an original non- (or low) thermally conductive and/or non- (or low) electrically conductive carrier substrate that has been removed.