Laser Line Focus Phase Mask for Symmetric Substrate Separation
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Solution Overview
Problem
Existing laser-based methods for separating substrates along a curved surface result in asymmetric separating surfaces due to uneven energy distribution, requiring rework steps like polishing to achieve symmetry, especially in thick substrates.
Innovation Solution
A method controlling energy distribution within a substrate using a phase mask to influence the laser beam, allowing for symmetrical modification by shifting the energy deposition along the focus trajectory, thereby achieving symmetrical curvature of the separating surface without the need for rework.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser energy is deposited along the focus trajectory without phase mask control, then material modification occurs, but the separating surface becomes asymmetric
Solution Approach 1:
A phase mask is introduced as an intermediary optical element between the laser beam and the substrate. The phase mask modulates the laser beam's phase distribution to control the energy deposition pattern, creating symmetric modification around the vertex point without requiring complex mechanical adjustments to the laser system itself.
Solution Approach 2:
The patent changes the phase distribution parameter of the laser beam by using a phase mask with specific phase profiles (e.g., cubic phase). This parameter change transforms the intensity distribution along the focus trajectory, enabling symmetric energy deposition and symmetric material modification around the vertex point.
2Reliability
If the vertex point of the line focus is shifted to achieve sufficient modification along the entire thickness region, then energy deposition is improved, but the separating surface becomes asymmetric
Solution Approach 1:
Instead of physically shifting the vertex point position, the patent changes the phase distribution parameter of the laser beam through the phase mask. This allows the energy deposition to be centered at the vertex point while still achieving sufficient modification along the entire thickness region through controlled phase modulation.
Solution Approach 2:
The patent intentionally introduces asymmetric phase distribution (e.g., cubic phase) in the optical domain to achieve symmetric energy deposition in the spatial domain. The asymmetric phase mask profile compensates for the natural asymmetric energy distribution of the laser focus, resulting in symmetric material modification.
3Ease of manufacture
If conventional laser focusing is used without phase mask, then the process is simple, but rework steps like polishing are required to achieve symmetry
Solution Approach 1:
The phase mask is used to pre-control the energy deposition pattern before material modification occurs. By shaping the phase distribution in advance, the laser creates symmetric modification directly during the initial processing step, eliminating the need for subsequent polishing or other corrective post-processing operations.
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
Enables the formation of symmetrical curved separating surfaces directly after separation, even in thick substrates, by precisely controlling the energy distribution within the substrate material, ensuring uniform modification and reducing the need for post-processing steps like polishing.
Implementation Method 1
controlling the energy distribution within the substrate at least partly by influencing the laser beam by at least one phase mask
Implementation Method 2
the deposition of the laser pulse energy around the vertex point of a curved line focus makes it possible to reliably attain a curved modification of the substrate material
Data Source
AI summary
A method for controlling an energy distribution introduced by at least one line focus of at least one laser beam in a substrate is performed by forming the line focus at least regionally in the substrate and influencing the laser beam with at least one phase mask to control the energy distribution in the substrate.