Laser Substrate Separation via Non-Linear Self-Focusing
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Solution Overview
Problem
Current methods for separating substrates, such as glass wafers, are inefficient and costly due to unsatisfactory edge quality, high processing time, and energy consumption, particularly in producing a large number of separating surfaces without sequential removal.
Innovation Solution
A method utilizing pulsed laser radiation with non-linear self-focusing effects, where the focal length difference exceeds substrate thickness, enabling anisotropic material removal through liquid or dry etching without tracking the laser focus, reducing processing time and energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If diamond cutting tools are used for substrate separation, then the separation process can be carried out at high speed (30 cm/sec), but the edge quality becomes unsatisfactory leading to increased cleaning costs and reduced product reliability
Solution Approach 1:
The patent replaces mechanical diamond cutting tools with a laser-based separation system. The laser beam modifies the substrate material along the beam axis through optical energy, eliminating mechanical contact and associated edge damage. This substitution maintains high separation speed while dramatically improving edge quality by avoiding mechanical stress and chip generation.
Solution Approach 2:
The patent utilizes laser wavelength and pulse duration parameters to achieve precise material modification. By selecting appropriate laser parameters (wavelength, pulse width, intensity), the process achieves clean separation without the edge damage characteristic of mechanical cutting, resolving the contradiction between speed and quality.
2Manufacturing precision
If sequential removal methods are used to create separating surfaces, then manufacturing precision can be maintained, but processing time increases significantly reducing productivity
Solution Approach 1:
The laser performs preliminary modification of the substrate material along the entire separating line simultaneously through rapid scanning, rather than sequential removal. This preliminary action creates a modified zone that enables subsequent clean separation, dramatically reducing processing time while maintaining precision.
Solution Approach 2:
The laser beam continuously scans along the separating line without interruption, maintaining constant material modification along the entire separation path. This continuous action eliminates the need for multiple sequential operations, reducing processing time while ensuring uniform separating surface quality throughout.
3Manufacturing precision
If high energy laser pulses are used to modify substrate material, then separation quality improves, but energy consumption increases
Solution Approach 1:
The patent employs pulsed laser radiation with optimized pulse duration and repetition rate. By using periodic pulses rather than continuous high-power radiation, the process achieves necessary material modification while allowing thermal relaxation between pulses, significantly reducing overall energy consumption compared to continuous high-energy operation.
Solution Approach 2:
The patent optimizes laser parameter combinations (wavelength, pulse duration, intensity, repetition rate) to achieve efficient material modification at lower energy levels. By tuning these parameters, the process maintains high separation quality while minimizing energy input, resolving the contradiction between modification quality and energy consumption.
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 simplifies the separation process by eliminating the need for focus tracking, significantly reducing processing time and energy consumption while ensuring high-quality separation surfaces with minimal material removal.
Implementation Method 1
the laser radiation being focused by non-linear self-focusing within the pulse duration of a single pulse through the same optical system
Implementation Method 2
separating a substrate... by means of a laser beam... using pulsed laser radiation
Implementation Method 3
the subsequent separation process is carried out by anisotropic removal essentially along the separating line
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3c
AI summary
The invention relates to a method and device for separating a substrate (2) by means of a laser beam (3). The duration of the effect of the laser beam (3) is extremely short such that the substrate (2) is only modified concentrically about the laser beam axis (Z) without it degrading the substrate material. Whilst the laser beam (3) acts upon the substrate (2), said substrate (2) moves relative to a laser machining head (10) such that a plurality of filament-type modifications are produced along a separating surface (5) which is to be incorporated. Said laser beam (3) is initially diverted by a transmission medium (8) having a higher intensity-dependent refractive index than air, and subsequently reaches the substrate (2). As the intensity of the used pulsed laser is not constant but increases to a maximum over the temporal course of the single pulse, and then reduces, the refractive index also changes. The focus point (9a) of the laser beam (3) moves between the outer surfaces (11, 12) of the substrate (2) along the beam axis (Z) such that it reaches the desired modification along the beam axis (Z) without correcting the laser machining head (10) in the z-axis.