Gallium Nitride Substrate Laser Separation for Lower Ingot Waste
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Solution Overview
Problem
The inefficiency and high waste generation in cutting gallium nitride substrates from ingots due to the use of inner peripheral blades, resulting in significant material loss and economic inefficiency.
Innovation Solution
A method involving the use of a laser beam to form a separating layer within the gallium nitride ingot, aligning focal points along specific crystal orientations to minimize cleavage and facilitate precise separation of substrates, reducing material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inner peripheral blade is used to cut the GaN substrate from the ingot, then the substrate can be separated from the ingot, but 60 to 70% of the GaN ingot is scraped off and discarded, resulting in high material loss
Solution Approach 1:
The patent applies preliminary action by forming a separating layer within the GaN ingot before the actual separation process. The laser beam irradiates the ingot to create a controlled separating layer at a predetermined depth, which then serves as a starting point for substrate separation. This preliminary preparation allows for precise control over where and how the separation occurs, minimizing material loss compared to conventional blade cutting methods.
Solution Approach 2:
The patent replaces the mechanical blade cutting system with a laser-based thermal processing system. Instead of using a physical inner peripheral blade that scrapes off large portions of the ingot, the invention uses a laser beam to induce controlled separation through thermal effects, creating a separating layer that enables precise substrate detachment with minimal material waste.
2Loss of substance
If a laser beam is used to form a separating layer by positioning the focal point inside the ingot, then material loss is reduced, but the process requires precise control of focal point positioning and crystal orientation alignment
Solution Approach 1:
The patent applies parameter changes by systematically varying the focal point position, laser beam intensity, and scanning speed to achieve optimal separating layer formation. By controlling these parameters and their relationships, the system can precisely position the separating layer at the desired depth while managing the complexity of multi-parameter coordination through established process guidelines.
Solution Approach 2:
The patent introduces crystal orientation as an intermediary factor that mediates between the laser processing and the desired separation outcome. By aligning the focal point positioning with specific crystal orientations ([1-10] and [1-10] directions), the system achieves controlled separation along predetermined paths, simplifying the overall control requirements through the guiding role of crystal structure.
3Manufacturing precision
If the separating layer is formed by irradiating the laser beam from the first surface, then the separating layer can be created at a controlled depth, but the process requires the laser wavelength to be transmissive to gallium nitride
Solution Approach 1:
The patent applies parameter changes by selecting specific laser wavelengths that are transmissive to gallium nitride, such as 1064 nm from Nd:YAG lasers. This wavelength selection enables controlled penetration depth while maintaining material integrity. The parameter of laser wavelength is optimized to balance penetration capability with separation precision, allowing the separating layer to be formed at the desired depth without excessive energy absorption that would compromise the process.
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
Enhances the efficiency of substrate production by minimizing material loss and improving productivity through controlled crack formation along desired directions, thereby reducing unnecessary waste.
Implementation Method 1
forming a separating layer at a depth corresponding to a thickness of the gallium nitride substrate to be manufactured, by positioning a focal point of a laser beam having a wavelength transmissive to gallium nitride inside the gallium nitride ingot
Implementation Method 2
The separating includes forming a plurality of focal points by branching the laser beam and setting the focal points such that a straight line connecting the branched focal points is along a direction parallel to a direction of a crystal orientation
Data Source
AI summary
A method for manufacturing a gallium nitride substrate from a gallium nitride ingot includes: holding the gallium nitride ingot; forming a separating layer at a depth corresponding to a thickness of the gallium nitride substrate to be manufactured, by positioning a focal point of a laser beam inside the gallium nitride ingot and relatively moving the gallium nitride ingot and the focal point along a direction of a crystal orientation represented by the following formula (1) of the gallium nitride ingot; and separating the gallium nitride substrate from the gallium nitride ingot with the separating layer as a starting point. The separating includes forming a plurality of focal points by branching the laser beam and setting the focal points such that a straight line connecting the branched focal points is along a direction parallel to a direction of a crystal orientation represented by the following formula (2).1 0 1 0 formula (1)1 1 2 0 formula (2)