Chip-Free Wafer Separation via Thermal Stress in Polymer Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wafer production methods, such as sawing, result in significant material loss (kerf loss), which is costly and inefficient, especially in the production of silicon wafers for solar cells, where over 50% of the material is lost, leading to high production costs.
Innovation Solution
A device for chip-free separation of wafers from a donor substrate using a multi-layer arrangement with a polymer receiving layer and a crack initiation device to generate stress-induced separation without contact, allowing for efficient and cost-effective wafer production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional sawing is used to produce wafers from an ingot, then the separation process is simple and reliable, but significant material loss occurs (kerf loss exceeding 50%)
Solution Approach 1:
The patent replaces the conventional mechanical sawing system with a thermal stress-based separation system. A polymer layer with high thermal expansion coefficient is applied to the workpiece, and through controlled heating and cooling, thermal stresses are induced to generate cracks that guide wafer separation without mechanical contact, thereby eliminating kerf loss.
Solution Approach 2:
The patent exploits thermal expansion differences between the polymer layer and the workpiece material. The polymer layer has a coefficient of thermal expansion approximately two orders of magnitude higher than the workpiece, allowing sufficiently high stresses to be induced during cooling to enable chip-free wafer detachment.
2Loss of substance
If a polymer layer is used to generate thermal stresses for wafer separation, then material loss is minimized, but the device complexity increases due to additional components
Solution Approach 1:
The patent combines multiple functions into a single integrated device. The applying device performs both crack initiation and crack propagation control through contactless stress application, eliminating the need for separate devices and reducing overall system complexity despite the sophisticated separation mechanism.
Solution Approach 2:
The patent introduces a fluidic substance as an intermediary medium to transmit stress to the multilayer arrangement. This fluidic substance acts as a mediator between the applying device and the workpiece, enabling contactless stress application and simplifying the interface between components.
3Device complexity
If the applying device generates both crack initiation and crack propagation stresses, then the device design becomes more compact and energy-efficient, but the control precision becomes more difficult
Solution Approach 1:
The patent employs dynamic control of the applying device to differentiate between crack initiation and crack propagation phases. By dynamically adjusting the parameters of contactless stress application, the device can precisely control crack behavior despite performing both functions with a single mechanism.
Solution Approach 2:
The patent implements feedback control mechanisms to monitor and adjust the stress application in real-time. This feedback system ensures precise control over crack initiation and propagation, maintaining manufacturing precision while using a compact integrated device design.
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
The device enables chip-free separation of wafers with minimal material loss, reducing production costs and improving efficiency, as it allows for targeted crack initiation and guidance, achieving a compact and energy-efficient design.
Implementation Method 1
the polymer layer exhibits a coefficient of thermal expansion approximately two orders of magnitude higher than that of the workpiece. Furthermore, by exploiting a glass transition, a relatively high modulus of elasticity can be achieved in the polymer layer, allowing sufficiently high stresses to be induced in the polymer layer-workpiece system during cooling to enable the wafer to detach from the workpiece.
Implementation Method 2
a contactless contacting device for applying stresses to the multilayer arrangement to generate crack-guiding stresses in the multilayer arrangement
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a device (1) for separating at least one wafer from a donor substrate (2). The device (1) according to the invention comprises at least a housing (4) with a receiving space (6) for receiving at least one multi-layer arrangement (8) which consists of at least one donor substrate (2) and a receiving layer (10) arranged or generated thereon, and an application device (12) for the contactless application of the multi-layer arrangement (8) for generating crack-conducting stresses in the multi-layer arrangement (8).