Light-Emitting Element Fabrication With Isolation Trenches
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Solution Overview
Problem
The existing methods for fabricating light-emitting elements, such as chemical lift-off (CLO) and laser lift-off (LLO), apply significant stress to the light-emitting structure, potentially causing cracks and are costly due to the difficulty in implementing substrates made of gallium nitride (GaN) series, which necessitates the use of heterogeneous substrates.
Innovation Solution
A method involving the formation of element isolation patterns, a buffer layer, and light-emitting structure layers on a substrate, followed by etching to create element isolation trenches, injecting a lift-off solution to remove the patterns, and then removing the substrate using a laser beam, with a support substrate bonded to reduce stress and using hydrogen fluoride as the lift-off solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chemical lift-off (CLO) method is used to remove substrate, then substrate can be removed from light-emitting structure, but stress is applied to light-emitting structure causing potential damage
Solution Approach 1:
The patent introduces element isolation trenches as an intermediary structure between the substrate and light-emitting structures. These trenches allow lift-off solution to be injected and enable stress-free substrate removal by providing a separation path that prevents direct mechanical stress transmission to the light-emitting structures.
Solution Approach 2:
The patent segments the substrate removal process into distinct regions by creating element isolation trenches that divide the substrate into separate zones. This segmentation allows selective removal and reduces overall stress on the light-emitting structures by isolating different regions during the lift-off process.
2Ease of manufacture
If laser lift-off (LLO) method is used to remove substrate, then substrate can be removed from light-emitting structure, but high-power laser beam causes stress and cracks in light-emitting structure
Solution Approach 1:
The element isolation trenches act as an intermediary that protects the light-emitting structures from direct laser beam exposure. By injecting lift-off solution into these trenches, the patent enables chemical separation without requiring high-power laser irradiation that would otherwise directly contact and damage the light-emitting structures.
Solution Approach 2:
The patent replaces the mechanical/thermal stress-based LLO method with a chemical lift-off approach using element isolation trenches. Instead of using high-power laser beams to mechanically separate the substrate, the patent uses chemically injected lift-off solution to dissolve or separate the substrate at the trench locations, eliminating laser-induced damage.
3Ease of manufacture
If heterogeneous substrate is used instead of GaN substrate, then fabrication cost is reduced, but stress management becomes more challenging
Solution Approach 1:
The patent extracts or removes the problematic interface between heterogeneous substrate and light-emitting structure by creating element isolation trenches. This extraction eliminates the stress concentration points that would otherwise exist at the substrate-structure interface, allowing cost-effective heterogeneous substrates to be used without suffering from lattice mismatch stresses.
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 method reduces stress on the light-emitting element, minimizes damage, and facilitates the removal of the substrate while maintaining the integrity of the light-emitting structure, addressing the challenges of stress and cost associated with existing techniques.
Implementation Method 1
injection of a lift-off solution into the element isolation trenches to remove the element isolation patterns
Implementation Method 2
removing the substrate from the light-emitting structures by radiating a laser beam to the substrate
Data Source
AI summary
A method of fabricating a light-emitting element, in which less stress is applied to the light-emitting element, includes: forming element isolation patterns on a substrate; forming a buffer layer on an entire surface of the substrate to directly contact the surface of the substrate and the element isolation patterns and forming light-emitting structure layers on the buffer layer; forming element isolation trenches, which overlap at least part of the element isolation patterns, respectively, buffer layer patterns and light-emitting structures which are separated from each other by the element isolation trenches, respectively, by etching the buffer layer and the light-emitting structure layers; injecting a lift-off solution into the element isolation trenches to remove the element isolation patterns; and removing the substrate.