Wafer Separation Aid for Controlled Mechanical Tension
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Solution Overview
Problem
The challenge in the semiconductor industry is to safely and gently separate wafers from their carriers during thinning processes, especially for very thin and mechanically sensitive wafers, where traditional methods often result in breakage due to uncontrolled mechanical stress and residue issues from adhesion layers.
Innovation Solution
A method involving a layer system with a separation aid that generates mechanical tension and fixes the second carrier behind the separation front, allowing for controlled mechanical separation using a single partition front, with optional vibration or temperature changes to facilitate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional mechanical separation methods are used to separate wafers from carriers, then the separation process is simple, but the wafer is subjected to uncontrolled mechanical stress causing breakage
Solution Approach 1:
The patent introduces a separation aid as an intermediary component between the wafer and carrier. This separation aid has controlled mechanical properties that allow it to mediate the separation process, distributing mechanical stress evenly across the wafer surface and preventing uncontrolled stress concentrations that would cause breakage.
Solution Approach 2:
The patent changes the mechanical parameters of the separation system by introducing a separation aid with specific elastic modulus and thickness parameters. These parameter changes allow the system to transition from direct mechanical contact (high stress) to mediated contact (controlled stress), enabling safe separation of thin wafers.
2Reliability
If a connecting layer is used between the wafer and carrier to compensate for topographical unevenness, then adhesion and surface compensation are improved, but residue remains on the wafer surface after separation requiring cleaning
Solution Approach 1:
The patent extracts the adhesive function from the separation process by using a separation aid that mechanically facilitates separation without relying on adhesive breakdown. The separation aid is designed to separate cleanly from the wafer surface, taking out the residue problem while maintaining the necessary adhesion during the thinning process.
Solution Approach 2:
The separation aid acts as an intermediary that replaces the traditional connecting layer. Instead of using adhesive materials that leave residue, the separation aid uses controlled mechanical properties to achieve separation, mediating between the wafer and carrier without contaminating the wafer surface.
3Manufacturing precision
If the wafer is thinned to very small thickness, then the final product specifications are met, but the wafer loses mechanical stability and becomes highly susceptible to breakage
Solution Approach 1:
The patent applies beforehand cushioning by introducing a separation aid with appropriate mechanical properties before the thinning process completes. This separation aid cushions the wafer during subsequent handling and separation operations, protecting the mechanically vulnerable thin wafer from breakage while allowing the thinning to proceed to the required specifications.
Solution Approach 2:
The separation aid functions as a flexible support structure that can accommodate the thin wafer's mechanical limitations. The flexible properties of the separation aid provide the necessary mechanical stability during separation without interfering with the thin wafer's final dimensions or specifications.
4Strength
If hard carriers are used to stabilize very thin wafers during thinning, then mechanical stability is improved, but separation becomes difficult due to high adhesive forces
Solution Approach 1:
The separation aid serves as an intermediary between the hard carrier and the wafer. During thinning, the hard carrier provides necessary mechanical stability. During separation, the separation aid mediates the interaction, allowing the hard carrier to be separated from the thin wafer without requiring excessive force that would damage the wafer.
Solution Approach 2:
The patent changes the mechanical parameters of the separation interface by introducing the separation aid. This allows the system to maintain the hard carrier's stabilizing function during thinning while changing the separation mechanics to enable easy, damage-free removal of the carrier.
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 ensures safe and controlled separation of wafers from their carriers, minimizing mechanical stress and avoiding residue on the wafer surface, thereby reducing breakage and simplifying the cleaning process.
Implementation Method 1
Generating a mechanical tension in the area of the interface between the carrier composite and the layer composite, so that the layer composite is separated from the carrier composite
Implementation Method 2
generating a vibration in the layer system
Implementation Method 3
changing the temperature of the layer system or parts of the layer system
Data Source
Figure 1
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Figure 4
AI summary
The invention relates to a method for mechanically separating a laminar structure (8) from a carrier assembly (1a) comprising or consisting of a first carrier (1), wherein the laminar structure (8) comprises a wafer (7) and optionally a second, stretchable carrier (20), comprising the following steps: a) providing a layer system (1a, 8) comprising the carrier assembly (1a) and the laminar structure (8), b) creating a mechanical stress in the region of the boundary surface between the carrier assembly (1a) and the laminar structure (8), so that the laminar structure (8) is separated from the carrier assembly (1a), by a method comprising i) the steps: i a) providing a separating aid (29), i b) fixing the separating aid (29) on the second carrier (20) such that, during the separating operation, the second carrier (20) remains fixed to the separating aid (29) directly behind a separating front (33) occurring during separation, and i c) mechanically separating the laminar structure (8) from the carrier assembly (1a) by using a separating front (33), and/or ii) the following step: ii) creating a vibration in the layer system (1a, 8), and/or iii) the following step: iii) changing the temperature of the layer system (1a, 8) or parts of the layer system (1a, 8) with the proviso that, if the method does not include the steps i a) - i c), the steps ii) and/or iii) lead to complete separation of the laminar structure from the carrier assembly.