Glass Substrate Separation With Self-Focusing Nanosecond Pulses
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Solution Overview
Problem
Existing methods for separating glass substrates, such as those used in microchip interposers, face challenges in achieving high-quality edges and efficient production of multiple separating faces, often requiring expensive femtosecond or picosecond lasers and complex configurations, which are time-consuming and costly.
Innovation Solution
A method utilizing pulsed laser radiation with non-linear self-focusing within the pulse duration, allowing for focal depth changes without tracking the laser focus, enabling efficient substrate modification along a separating line without material removal through the substrate, and subsequent anisotropic material removal for separation.
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/s), but the edge quality becomes unsatisfactory
Solution Approach 1:
The patent replaces mechanical diamond cutting tools with a laser-based separation method. The laser beam modifies the substrate material along a desired separating line through optical energy, eliminating mechanical contact and the associated edge damage while maintaining high separation speed.
Solution Approach 2:
The patent changes the physical state and properties of the substrate material along the separating line through laser irradiation. The laser induces material modification (such as melting, vaporization, or structural change) that creates a clean separation path, transforming the separation process from mechanical to optical-thermal.
2Manufacturing precision
If femtosecond or picosecond lasers are used for substrate separation, then high-quality separating faces can be produced, but the equipment cost and process complexity increase significantly
Solution Approach 1:
The patent employs nanosecond laser pulses with durations of 1-100 ns, which are longer and less expensive than femtosecond or picosecond lasers. This substitution maintains sufficient material modification capability while dramatically reducing equipment cost and system complexity.
Solution Approach 2:
The patent optimizes the laser pulse duration parameter to the nanosecond range (1-100 ns), which provides an optimal balance between material modification quality and equipment accessibility. This parameter selection avoids the need for expensive ultrashort pulse lasers while still achieving high-quality separating faces.
3Quantity of substance
If multiple focal points are used to produce filaments in different layers, then multiple separating faces can be created, but the processing time and control complexity increase
Solution Approach 1:
The patent uses periodic nanosecond laser pulses with repetition rates optimized for the substrate thickness. The periodic pulse delivery enables efficient material modification through cumulative heating and stress accumulation, allowing multiple separating faces to be created without requiring complex multi-focus configurations.
Solution Approach 2:
The patent employs a single focal point that can create multiple separating faces by utilizing the propagation of laser-induced filaments through different substrate layers. The same laser parameter set and focal position can produce separations at multiple depths, eliminating the need for independent focal point control for each layer.
4Stability of the object's composition
If a time delay between successive pulses is smaller than the material relaxation duration, then continuous material modification can be achieved, but the energy efficiency decreases
Solution Approach 1:
The patent employs periodic nanosecond laser pulses with repetition rates specifically chosen to match or exceed the material relaxation time. This periodic action ensures that each pulse builds upon the modification created by the previous pulse, achieving continuous material transformation while maintaining optimal energy efficiency through cumulative heating effects.
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 significantly reduces processing time and control system requirements, allowing for rapid and cost-effective production of high-quality separating faces in glass substrates, eliminating the need for complex focal point tracking and external force applications.
Implementation Method 1
the pulsed laser radiation being focused by the optical system, which is unchanged per se, by non-linear self-focusing within the pulse duration (t) of an individual pulse (P) of the pulsed laser radiation at a focal depth (f2) different from the original focal depth (f1)
Implementation Method 2
the substrate is irradiated with laser light in such a way that a multiphoton absorption phenomenon is produced within the substrate, whereby a light convergence point and thus a modified area are formed within the substrate
Implementation Method 3
the laser pulses are selected in such a way, in terms of the energy and pulse duration, that a duct-like filament is produced within the substrate
Data Source
AI summary
An aspect of the invention provides a device, comprising: a laser machining head configured to deflect laser radiation onto an optical system comprising a substrate, the device being configured to carry out a method for separating the substrate using the optical system, the optical system being configured to provide the laser radiation, a thickness of the substrate not exceeding 2 mm in a region of a separating line, the method comprising: applying pulsed laser radiation having a pulse duration (t) to a substrate material of the substrate using the optical system, the substrate material being transparent at least in part to a laser wavelength of the pulsed laser radiation, the pulsed laser radiation being focused using the optical system at an original focal depth (f1), an intensity of the pulsed laser radiation leading to a modification of the substrate along a beam axis (Z) of the pulsed laser radiation.