Adhesive-Free Multi-Layer CMP Polishing Pad Design
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Solution Overview
Problem
Existing multi-layer polishing pads for chemical-mechanical polishing rely on adhesives to join layers and affix windows, which are costly, limited in material and construction types, and prone to delamination and chemical attack, leading to inefficiencies and reliability issues.
Innovation Solution
A multi-layer polishing pad design that mechanically interlinks layers without adhesives, using physical overlap and intertwinement of polymer resins, allowing for different physical and chemical properties in each layer, and incorporating optically transmissive regions for in-situ endpoint detection, with layers joined through methods like coextrusion or foaming processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesives are used to join polishing pad layers and affix windows, then the layers can be easily bonded together, but the adhesives are susceptible to chemical attack, leading to delamination and reduced reliability
Solution Approach 1:
The patent removes the adhesive layer entirely from the polishing pad construction. Instead of using adhesives to bond the porous support layer to the polishing layer or to affix the window, the invention uses mechanical interlocking features such as recesses and protrusions that physically engage with each other, eliminating the chemical bonding interface that is susceptible to delamination.
Solution Approach 2:
The patent introduces mechanical interlocking features (recesses and protrusions) as an intermediary mechanism between layers. These features serve as a physical mediator that transfers and distributes mechanical stresses across layer interfaces, replacing the chemical bonding function of adhesives with a mechanical bonding system that is resistant to chemical attack and delamination.
2Ease of manufacture
If adhesives are used to join polishing pad layers, then bonding can be achieved, but the process requires curing time of 24 hours or more, reducing productivity
Solution Approach 1:
The patent eliminates the adhesive curing step by removing the adhesive material from the construction process. The mechanical interlocking features allow layers to be assembled and secured immediately without requiring time for chemical curing, thereby eliminating the 24-hour or longer waiting period associated with adhesive-based manufacturing.
3Ease of manufacture
If adhesives are used to affix windows to the polishing pad, then the window can be attached, but the adhesive can be attacked by polishing composition chemicals, leading to window dislodgement
Solution Approach 1:
The patent removes the adhesive layer from the window attachment process. Instead of chemically bonding the window to the polishing pad, the invention uses mechanical retention features such as recesses that physically hold the window in place, creating a chemical-resistant attachment system.
Solution Approach 2:
The patent introduces mechanical retention features as an intermediary between the window and the polishing pad. These features serve as a physical mediator that secures the window through mechanical engagement rather than chemical adhesion, protecting the window attachment from chemical attack by the polishing composition.
4Reliability
If adhesive-free mechanical interlinking is used to join layers, then reliability and resistance to delamination are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent divides the polishing pad into distinct functional layers (porous support layer, polishing layer, window) with defined interfaces. Each layer can be manufactured separately using optimized processes, and the mechanical interlocking features are integrated as part of the layer structures themselves, allowing for modular manufacturing that simplifies the overall process despite the elimination of adhesives.
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 adhesive-free design enhances the reliability and efficiency of polishing pads by preventing delamination, reducing chemical susceptibility, and enabling cost-effective production with improved optical transparency for endpoint detection, thus ensuring consistent and accurate polishing processes.
Implementation Method 1
the layers are joined together through the physical overlap and intertwinement of the polymer resins
Implementation Method 2
placing a polymer sheet under pressure in the presence of a CO2 gas for a period of time
Implementation Method 3
foaming the polymer sheet by heating the sheet to a temperature above the glass transition temperature of the polymer
Implementation Method 4
heating the sheet to a temperature above the glass transition temperature of the polymer
Implementation Method 5
the bottom layer is substantially optically transmissive
Data Source
Figure 1~6
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AI summary
The invention is directed to a multi-layer polishing pad (10) for chemical- mechanical polishing comprising a porous polishing layer (12) and a porous bottom layer (14) , wherein the bottom layer (14) is substantially coextensive with the polishing layer (12) , the polishing layer (12) being joined to the bottom layer without the use of an adhesive; the polishing layer (12) having an average surface roughness, Ra, that is greater than the Ra of the bottom layer.