LED Fabrication Using Patterned Sapphire Carrier and Laser Lift-Off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional fabrication processes of light-emitting diode (LED) devices face high substrate wafer loss and complex sapphire carrier removal, leading to increased costs and reduced yield, especially for small-area LED chips.
Innovation Solution
A method involving a carrier with insulating micro patterns, where a laser lift-off process focuses on a planar interface between the sapphire carrier and silicon oxide micro patterns, followed by wet etching to form μm-scaled recess structures and a surface-roughing process to achieve nm-scaled roughness, enhancing light-emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional substrate wafer sawing process is used to fabricate small-area LED chips, then individual LED chips can be obtained, but substrate wafer loss increases and total light-emitting area is reduced
Solution Approach 1:
The patent segments the sapphire carrier into multiple individual carriers, each capable of supporting an LED chip structure. This segmentation allows the LED chip to be formed and transferred without requiring extensive substrate wafer area, thereby reducing substrate loss and increasing total light-emitting area utilization.
Solution Approach 2:
The patent introduces a patterned sapphire carrier as an intermediary substrate that facilitates LED chip formation and subsequent transfer to the final substrate. This intermediary approach enables efficient use of the sapphire carrier material while minimizing waste of the expensive LED chip substrate material.
2Ease of manufacture
If conventional sapphire carrier removal process is adopted, then LED chip can be released, but fabrication cost increases and yield control becomes complex
Solution Approach 1:
The patent replaces the conventional mechanical or chemical sapphire carrier removal process with a laser-based lift-off method. The laser beam selectively removes the patterned sapphire carrier material without requiring complex chemical etching or mechanical processes, simplifying the fabrication workflow and improving yield control.
Solution Approach 2:
The patent utilizes laser parameters (wavelength, power, pulse duration) to precisely control the carrier removal process. By adjusting these parameters, the laser can selectively ablate the patterned sapphire carrier while leaving the LED chip structure intact, providing a controllable and simplified removal mechanism.
3Productivity
If laser lift-off process is applied to remove sapphire carrier, then carrier can be removed, but high energy density may damage the LED device
Solution Approach 1:
The patterned sapphire carrier is segmented into discrete regions that can be selectively removed by the laser. This segmentation allows the laser energy to be concentrated on specific areas without exposing the entire LED structure to high energy density, reducing the risk of damage while maintaining removal efficiency.
Solution Approach 2:
The patent creates regions of different material composition and structure (patterned sapphire regions versus protected LED chip regions) with distinct laser absorption characteristics. This local quality difference enables selective laser removal of the carrier while protecting the LED device, as the laser energy is preferentially absorbed by the patterned sapphire regions.
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 reduces the maximum energy density of the laser beam, prevents damage to the LED device, improves process yield, and increases light-emitting efficiency by creating roughened surfaces on the semiconductor layer.
Implementation Method 1
The carrier is lifted off from the light-emitting lamination layer by a laser lift-off process
Data Source
AI summary
The invention provides a method for fabricating a light-emitting diode device. The method includes providing a carrier having a first surface and a second surface. The first surface has insulating micro patterns. A buffer layer, a first-type semiconductor layer, a light-emitting layer and a second-type semiconductor layer are grown on the first surface to form a light-emitting lamination layer. A substrate is provided for the second-type semiconductor layer to bond on. The carrier is lifted off from the light-emitting lamination layer by a laser lift-off process, and surfaces of the insulating micro patterns and a surface of the barrier layer between the insulating micro patterns are exposed. The insulating micro patterns and the barrier layer are removed. Recess structures are formed on the first-type semiconductor layer. A surface-roughing process is then performed on the recess structures.