Laser Wafer Peeling Layer Scanning for Stable Ingot Separation
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Solution Overview
Problem
Conventional wafer manufacturing methods from ingots face inefficiencies due to variations in depth positions of modified layers, leading to increased processing margins for grinding or polishing and reduced manufacturing efficiency.
Innovation Solution
A wafer manufacturing method involving a peeling layer forming step where a laser beam is scanned across the ingot surface in multiple directions to form linear scanning lines at consistent depth positions, reducing depth variations and processing margins, and a wafer peeling step that uses a unidirectional load to stabilize cleavage and improve peeling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser irradiation is used to form modified layers, then wafers can be produced from ingots, but depth variations in modified layers increase processing margins for grinding or polishing
Solution Approach 1:
The patent divides the laser irradiation process into multiple scanning passes, where the laser beam scans the ingot surface in a first direction to form scanning lines, then scans in a second direction orthogonal to the first direction. This segmentation of the irradiation path ensures that modified layers are formed at consistent depth positions across the entire ingot surface, reducing depth variations and minimizing processing margins required for subsequent grinding or polishing operations.
Solution Approach 2:
The patent introduces a two-dimensional scanning approach by irradiating the ingot surface in both a first direction and a second direction orthogonal to the first direction. This multi-directional scanning ensures uniform energy distribution and consistent modified layer depth across the surface, eliminating depth variations that would otherwise require excessive processing margins in conventional single-direction irradiation methods.
2Reliability
If conventional peeling methods are used, then wafers can be separated from the ingot, but peeling stability is insufficient leading to material wastage
Solution Approach 1:
The patent applies a unidirectional load to the ingot in the peeling direction before and during the peeling process. This preliminary application of force in the same direction as the desired peeling ensures that cleavage occurs stably along the modified layer interface, preventing deviations or failures in the peeling process. The pre-applied unidirectional force maintains consistent stress distribution, ensuring reliable separation and reducing material wastage.
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 enhances manufacturing efficiency by reducing depth variations in the peeling layer, minimizing processing margins, and stabilizing the wafer peeling process, resulting in improved surface quality and reduced material wastage.
Implementation Method 1
a peeling layer forming step that irradiates a surface (21) of one end side of the ingot in a height direction thereof with a laser beam having a permeability to the ingot, thereby forming a peeling layer at a depth position corresponding to a thickness of the wafer from the surface
Implementation Method 2
the peeling layer forming step performs laser scanning that irradiates the surface with the laser beam while causing an irradiation position (PR) of the laser beam to move on the surface in a first direction (Ds) across the surface
Implementation Method 3
a wafer peeling step that peels a wafer precursor (26) as a portion between the surface and the peeling layer from the ingot, the wafer precursor being peeled at the peeling layer
Data Source
AI summary
A surface of one end side of an ingot in a height direction thereof is irradiated with a laser beam having a permeability to the ingot, thereby forming a peeling layer at a depth position corresponding to a thickness of the wafer from the surface. A laser scanning irradiating the laser beam is performed for a plurality of times changing the irradiation position in a second direction while causing an irradiation position of the laser beam to move in a first direction. With a single laser scanning, a plurality of laser beams are irradiated in which irradiation positions are different in the first direction and the second direction.