Laser Annealing Sequence for Modified Layer Formation on Rough Surfaces
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Solution Overview
Problem
Laser machining methods face challenges in forming modified layers inside objects with rough or non-flat irradiation surfaces, as the laser beam may be absorbed or scattered, preventing appropriate layer formation.
Innovation Solution
A laser machining method involving two steps: first, using a shorter-pulse laser beam for laser annealing to flatten the irradiation surface, and second, using a longer-pulse laser beam to form modified layers inside the object, where the first laser beam's pulse pitch is shorter than the second, allowing continuous recrystallization and appropriate flattening of the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is used to form modified layers inside an object with a rough irradiation surface, then the modified layers may be appropriately formed, but the laser beam may be absorbed or scattered on the rough surface, preventing appropriate layer formation
Solution Approach 1:
The patent applies preliminary action by performing laser annealing to flatten the irradiation surface before forming the modified layer. The first laser beam irradiates the surface to create a flat, smooth irradiation surface, which then allows the second laser beam to form the modified layer accurately without scattering or absorption issues caused by surface roughness.
2Manufacturing precision
If laser annealing is performed to flatten the irradiation surface, then the surface quality is improved, but additional processing time is required
Solution Approach 1:
The patent merges the surface flattening process and the modified layer formation process into a single integrated operation. By using a laser beam with dual functionality that can perform both laser annealing (surface flattening) and modified layer formation in sequence, the patent eliminates the need for separate processing steps, thereby reducing total processing time while maintaining surface quality.
3Manufacturing precision
If the pulse pitch of the laser beam for laser annealing is shortened, then continuous recrystallization and flattening are achieved, but the complexity of laser parameter control increases
Solution Approach 1:
The patent applies parameter changes by adjusting the pulse pitch of the first laser beam to be shorter than the pulse pitch of the second laser beam. This specific parameter setting enables continuous recrystallization and effective surface flattening during laser annealing, while the control unit manages the parameter transitions automatically, reducing the perceived complexity for the operator.
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 effectively flattens the irradiation surface and allows for appropriate formation of modified layers inside the object, improving the machining process by reducing the number of passes required for layer formation and enhancing surface quality.
Implementation Method 1
a first step of flattening an irradiation surface through laser annealing by irradiating a surface or a back surface of an object with a first laser beam
Implementation Method 2
a region that is recrystallized and flattened after melting can be continuously formed
Implementation Method 3
a second step of forming a modified layer inside the object by irradiating the irradiation surface, which is flattened in the first step, with a second laser beam
Data Source
AI summary
A laser machining method performed by a laser machining device includes: a first step of flattening an irradiation surface through laser annealing by irradiating a surface or a back surface of an object with a laser beam, the object including a functional element layer on a surface side; and a second step of forming a modified layer inside the object by irradiating the irradiation surface, which is flattened in the first step, with a laser beam. A pulse pitch of the laser beam is shorter than a pulse pitch of the laser beam.