GaN Substrate Peeling Layer Alignment for Low-Waste Slicing
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Solution Overview
Problem
The existing methods for slicing gallium nitride (GaN) substrates from ingots result in significant waste, with up to 60-70% of the ingot being discarded due to the thickness of inner diameter blades used, leading to inefficiencies in manufacturing.
Innovation Solution
A manufacturing method involving the formation of a peeling layer using a laser beam that is split into focal points, aligned with specific crystal orientations of the GaN ingot, to efficiently slice and separate the substrate while minimizing the occurrence of cracks and irregularities on the severed surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inner diameter blade is used to slice the GaN ingot, then the substrate can be separated from the ingot, but the blade thickness causes significant material waste (60-70% discard rate)
Solution Approach 1:
The patent replaces the mechanical slicing blade with a laser beam system. The laser beam forms a peeling layer inside the GaN ingot through optical-thermal interaction, eliminating the need for physical contact with a thick blade. This substitution of mechanical slicing with optical-field-based peeling removes the blade thickness constraint entirely, enabling precise substrate separation without the 60-70% material waste associated with mechanical blades.
Solution Approach 2:
The patent changes the physical state and properties of the GaN ingot by using laser irradiation to create a peeling layer. By controlling laser parameters (wavelength, power, scanning speed) and aligning them with the crystal orientation <1-1 00>, the process transforms the intact ingot into a state with a predefined peeling layer, enabling clean separation. This parameter control approach replaces the fixed geometric constraint of blade thickness with adjustable laser processing parameters.
2Ease of manufacture
If the laser beam is applied without aligning with crystal orientation, then the peeling process can be simplified, but cracks occur on the severed surface increasing irregularities
Solution Approach 1:
The patent applies local quality by specifically targeting the laser beam along the <1-1 00> crystal orientation direction of the GaN ingot. This directional alignment exploits the anisotropic properties of the crystal structure, where the peeling layer forms preferentially along specific crystallographic planes. By localizing the laser energy deposition to this specific orientation, the process achieves clean peeling without cracks, as the peeling layer forms along the natural cleavage planes of the crystal structure.
Solution Approach 2:
The patent performs preliminary action by pre-forming the peeling layer through controlled laser irradiation before the actual substrate separation. The laser processing creates a weakened peeling layer along the <1-1 00> orientation that serves as a predetermined separation plane. This preliminary formation of the peeling layer ensures that subsequent separation proceeds cleanly without cracks, as the damage is already localized to the intended peeling interface rather than propagating unpredictably through the substrate.
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 method allows for the efficient slicing and manufacturing of GaN substrates with reduced waste and improved surface quality by aligning the peeling process with the crystal orientations of the ingot, thereby enhancing the production efficiency and reducing the discard rate.
Implementation Method 1
forming a peeling layer by irradiating the gallium nitride ingot with a laser beam of a wavelength, which transmits through gallium nitride
Implementation Method 2
forming a peeling layer at a depth, which corresponds to a thickness of the gallium nitride substrate to be manufactured, by relatively moving the gallium nitride ingot and a focal point of a laser beam
Data Source
AI summary
A manufacturing method of a gallium nitride (GaN) substrate includes a peeling layer forming step of forming a peeling layer at a depth, which corresponds to a thickness of the gallium nitride substrate to be manufactured, by relatively moving a GaN ingot and a focal point of a laser beam of a wavelength, which transmits through GaN, along a direction of a crystal orientation of the GaN ingot as represented by the below-described formula (1) with the focal point positioned inside the GaN ingot, and a peeling step of peeling the GaN substrate from the GaN ingot using the peeling layer as a start point. The peeling layer forming step is set such that the laser beam is split to form a plurality of focal points and straight lines connecting the individual split focal points each extend along a direction parallel to the direction of the crystal orientation represented by the below-described formula (1).1 1 2 0 Formula (1)