Adhesive-Free Multi-Layer CMP Polishing Pad
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Solution Overview
Problem
Existing chemical-mechanical polishing (CMP) processes face challenges with adhesive-based multi-layer polishing pads, which suffer from harsh fumes, long curing times, chemical susceptibility, and potential delamination, leading to the need for efficient and cost-effective adhesive-free solutions for producing multi-layer pads with translucent regions.
Innovation Solution
A multi-layer polishing pad comprising a top layer, a middle layer of thermoplastic polyurethane with a lower Vicat softening temperature, and a bottom layer, bonded together without adhesives, using a lamination process that subjects the middle layer to temperatures above its softening point but below that of the other layers to form a strong bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesives are used to join polishing pad layers, then the layers can be bonded together, but the adhesives produce harsh fumes and require long curing times
Solution Approach 1:
The patent removes the adhesive layer entirely from the polishing pad construction. Instead of using adhesives to bond the polishing layer to the support layer, the invention uses a mechanical interlocking structure where the support layer is formed with protrusions that engage with recesses in the polishing layer, eliminating the need for adhesive curing time and associated environmental issues.
Solution Approach 2:
The patent introduces a mechanical intermediary structure (the protrusion-recess engagement mechanism) that mediates the bonding between layers. This mechanical intermediary replaces the chemical intermediary (adhesive) and achieves bond strength through physical interlocking rather than chemical bonding, thereby eliminating curing time requirements.
2Strength
If adhesives are used to join polishing pad layers, then the layers can be bonded together, but the adhesives are susceptible to chemical attack from polishing composition
Solution Approach 1:
The patent removes the adhesive layer that is vulnerable to chemical attack. By eliminating the adhesive and using direct mechanical bonding through protrusions and recesses, the system removes the component that is susceptible to degradation from polishing composition chemicals, thereby improving reliability.
Solution Approach 2:
The patent creates a homogeneous bonding interface through mechanical interlocking where the protrusion and recess structures are made from the same or compatible materials as the layers they connect. This eliminates the heterogeneous adhesive interface that creates chemical vulnerability, as the bonding structure is now integral to the layers themselves.
3Strength
If adhesives are used to join polishing pad layers, then the layers can be bonded together, but the bonding is imperfect and degrades over time causing delamination
Solution Approach 1:
The patent removes the adhesive layer that degrades over time. The mechanical interlocking structure provides a permanent bond that does not rely on chemical adhesion that can deteriorate, thereby extending the service life of the polishing pad by preventing delamination.
Solution Approach 2:
The patent incorporates the bonding structure into the manufacturing process itself, with protrusions and recesses being formed as integral parts of the layers during molding. This beforehand integration ensures that the bonding capability is built-in from the start and cannot degrade over time, providing long-term reliability.
4Strength
If adhesives are used to join polishing pad layers, then the layers can be bonded together, but the process is costly and limited in pad material options
Solution Approach 1:
The patent removes the adhesive application process entirely, simplifying manufacturing. The mechanical interlocking structures are formed directly during the molding process of the layers themselves, eliminating the need for separate adhesive application, positioning, and curing steps, thereby reducing cost and increasing manufacturing flexibility.
Solution Approach 2:
The patent merges the bonding structure with the layer structures themselves. The protrusions and recesses are formed as integral parts of the polishing layer and support layer during their respective molding processes, then the layers are assembled by engaging these pre-formed features. This combining of bonding and structural functions eliminates the need for separate adhesive materials and processes.
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 solution provides a stronger, adhesive-free bond that is resistant to high temperatures and allows for different physical and chemical properties in each layer, enhancing the durability and efficiency of the polishing pad while avoiding the drawbacks of adhesive-based methods.
Implementation Method 1
the thermoplastic polyurethane of the middle layer has a lower Vicat softening temperature than the top layer and/or the bottom layer
Data Source
Figure 1
Figure 2a~2b
Figure 3~4
AI summary
The invention is directed to a multi-layer polishing pad for chemical-mechanical polishing comprising a top layer, a middle layer and a bottom layer, wherein the top layer and bottom layer are joined together by the middle layer, and without the use of an adhesive. The invention is also directed to a multi-layer polishing pad comprising an optically transmissive region, wherein the layers of the multi-layer polishing pad are joined together without the use of an adhesive.