Lift-off Method with Zone-Specific Laser Irradiation
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Solution Overview
Problem
The existing lift-off methods using laser beams to separate optical device layers from epitaxy substrates often result in warping and uneven peeling, leading to reduced processing quality and increased processing time due to differential laser application across the composite substrate.
Innovation Solution
A lift-off method employing a pulsed laser beam with adjustable irradiation conditions for ring-shaped areas on the buffer layer, allowing for controlled peeling by changing the focused spot and output power levels to optimize peeling efficiency and prevent substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied to the composite substrate to break the buffer layer, then the optical device layer can be peeled off from the epitaxy substrate, but the composite substrate is liable to have warping and uneven peeling due to differential laser application across the substrate
Solution Approach 1:
The patent applies different irradiating conditions (power, pulse width, frequency) to different radial zones of the buffer layer. The buffer layer is divided into multiple regions with varying laser parameters - outer circumferential regions receive different irradiation than central regions, optimizing peeling uniformity across the entire substrate while preventing warping and damage to the optical device layer
2Productivity
If the laser beam is applied to accelerate peeling of unpeeled regions, then the processing speed increases, but the already peeled portions are damaged and processing quality decreases
Solution Approach 1:
The patent performs preliminary breaking of the buffer layer through controlled laser irradiation before attempting to peel off the optical device layer. By pre-weakening the buffer layer bonds in a controlled manner with appropriate laser parameters, the subsequent peeling process becomes faster and cleaner, preventing damage to already peeled regions while maintaining high processing quality
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 achieves desired processed results by ensuring uniform peeling and reducing processing time while maintaining product quality by applying a pulsed laser beam with specific settings to the buffer layer, effectively addressing the issues of warping and uneven peeling in existing methods.
Implementation Method 1
applying a pulsed laser beam having a wavelength transmittable through the epitaxy substrate and absorbable by the buffer layer to the buffer layer from a reverse side of the epitaxy substrate
Implementation Method 2
absorbable by the buffer layer
Data Source
AI summary
A lift-off method includes a relocation substrate joining step of joining a relocation substrate to a surface of an optical device layer of an optical device wafer with a joining member interposed therebetween, thereby forming a composite substrate, a buffer layer breaking step of applying a pulsed laser beam having a wavelength transmittable through an epitaxy substrate and absorbable by a buffer layer to the buffer layer from a reverse side of the epitaxy substrate of the optical device wafer of the composite substrate, thereby breaking the buffer layer, and an optical device layer relocating step of peeling off the epitaxy substrate from the optical device layer, thereby relocating the optical device layer to the relocation substrate. In the buffer layer breaking step, irradiating conditions of the pulsed la-ser beam are changed for respective ring-shaped areas of the buffer layer, and the pulsed laser beam is applied to the optical device wafer under the changed irradiating conditions.