Wafer Extraction via Laser-Induced Cracking and Thermal Stress
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Solution Overview
Problem
Current methods for producing wafers result in significant material losses due to sawing, which is costly and inefficient, and machining methods damage the material, introduce mechanical stresses, and affect surface quality.
Innovation Solution
A method involving a donor substrate with specified crack courses created by laser beams, bonded to a carrier substrate with a stress-producing layer that induces thermal stresses to remove the solid layer without material destruction, allowing for reuse of the carrier substrate and reducing material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sawing is used to produce wafers from ingots, then wafers can be produced, but significant material losses occur as kerf-loss
Solution Approach 1:
The patent extracts the desired solid layer from the donor substrate by inducing controlled cracks that propagate along predetermined paths, separating the solid layer without removing surrounding material. This extraction method eliminates the need for sawing and associated kerf losses.
Solution Approach 2:
The patent replaces the mechanical sawing process with a stress-induced cracking mechanism. By applying controlled stresses through thermal expansion mismatch between layers, the solid layer is separated from the donor substrate without mechanical contact, eliminating material loss.
2Manufacturing precision
If machining is used to adjust wafer thickness, then standard thickness is achieved, but material is destroyed and mechanical stresses are introduced
Solution Approach 1:
The patent performs thickness adjustment and separation actions before the wafer is fully processed. By pre-defining crack paths and pre-adjusting thickness through controlled stress application, the need for subsequent machining is eliminated, preserving material integrity and avoiding additional mechanical stresses.
Solution Approach 2:
The patent replaces mechanical machining operations with stress-induced crack propagation and thermal field control. Thickness precision is achieved through controlled stress application and crack propagation rather than material removal by cutting tools, thereby preserving mechanical strength.
3Manufacturing precision
If machining is used to process wafers, then thickness is standardized, but surface quality is degraded due to scoring
Solution Approach 1:
The patent replaces mechanical machining operations with stress-induced crack propagation and thermal field control. Surface quality is preserved because the separation process occurs through controlled cracking rather than mechanical contact with cutting tools that would score or damage the surface.
Solution Approach 2:
The patent introduces stress fields and thermal fields as intermediaries to achieve thickness uniformity and separation without direct mechanical contact. These intermediary fields enable precise control of the separation process while avoiding harmful mechanical interactions that would degrade surface quality.
4Manufacturing precision
If machining is used to remove material, then desired thickness is achieved, but heat and dust are produced
Solution Approach 1:
The patent replaces mechanical machining with stress-induced crack propagation and thermal field application. This substitution eliminates the generation of dust and excessive heat associated with mechanical cutting, as the separation process occurs through controlled stress release rather than friction-based material removal.
Solution Approach 2:
The patent changes the physical parameters of the separation process from mechanical contact to stress and thermal field control. By adjusting stress magnitude, thermal expansion coefficients, and crack propagation conditions, precise thickness control is achieved without the harmful byproducts of mechanical machining.
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 reduces material losses, maintains the solid layer's stability for processing, and prevents mechanical stress during removal, enabling efficient and cost-effective production of wafers with improved surface quality.
Implementation Method 1
producing modifications, in particular by means of laser beams, in the donor substrate in order to specify a crack course
Implementation Method 2
thermally loading the stress-producing layer in order to produce stresses in the donor substrate
Implementation Method 3
a crack is triggered by the stress production, which crack propagates along the specified crack course in order to remove the solid layer
Data Source
AI summary
A method for treating a solid layer includes: providing a multi-layer assembly having a carrier substrate and a solid layer bonded to the carrier substrate by a bonding layer, the solid layer having an exposed surface including a defined surface structure, the defined surface structure resulting from a removal, which is effected by a crack, from a donor substrate, at least in sections; processing the solid layer, which is arranged on the carrier substrate; and separating the solid layer from the carrier substrate by a destruction of the bonding layer.