Polishing Pad Window with Adhesive Sealant Gap Filling
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Solution Overview
Problem
Existing polishing pads with integrated windows face challenges such as delamination, leakage, and warping during the chemical mechanical polishing (CMP) process, particularly due to lateral frictional forces and the risk of scratching the window surface, which affects transparency and endpoint detection accuracy.
Innovation Solution
A polishing pad design featuring a light-transmitting body recessed within the polishing layer stack, secured by a fluid-impermeable layer and an adhesive sealant that laterally fills the gap between the light-transmitting body and the polishing layer, reducing the risk of delamination and leakage while maintaining transparency and endpoint detection capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light-transmitting body is integrated into the polishing pad for endpoint detection, then endpoint detection capability is improved, but the risk of delamination and leakage increases due to lateral frictional forces during CMP
Solution Approach 1:
The light-transmitting body is nested within a cavity formed in the polishing layer, creating a hierarchical structure where the light-transmitting body is contained within the polishing pad matrix. This nesting approach provides mechanical support and reduces delamination risk by embedding the window rather than surface-mounting it.
Solution Approach 2:
An adhesive sealant is introduced as an intermediary material between the light-transmitting body and the cavity walls. This sealant laterally fills the gap and provides enhanced bonding, mediating the mechanical stress transfer and preventing delamination while maintaining the optical function.
2Measurement precision
If the window is made larger to improve detection area, then endpoint detection accuracy is improved, but the risk of delamination increases due to greater lateral frictional forces
Solution Approach 1:
The cavity is formed to accommodate a larger light-transmitting body while maintaining it within the polishing layer matrix. This nested structure distributes the lateral frictional forces across the cavity walls and adhesive sealant, allowing larger window sizes without proportionally increasing delamination risk.
Solution Approach 2:
The window assembly uses composite construction with the light-transmitting body made of a softer material than the polishing layer, combined with an adhesive sealant that has about the same hardness as the light-transmitting body. This composite approach allows larger windows while managing stress distribution.
3Illumination intensity
If the light-transmitting body is positioned closer to the polishing surface to improve light transmission, then optical performance is improved, but the risk of scratching during polishing increases
Solution Approach 1:
The cavity is formed with specific depth and the light-transmitting body is positioned at an optimized distance from the polishing surface before polishing begins. This pre-positioning cushions the window from direct contact with abrasive particles and conditioning elements, protecting it from scratching while maintaining adequate light transmission.
Solution Approach 2:
The light-transmitting body is made of a softer material than the polishing layer, creating a material hierarchy where the softer window is protected by the harder polishing layer during conditioning and polishing operations, preventing scratches while allowing optical function.
4Reliability
If adhesive sealant is used to laterally fill the gap, then delamination resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The cavity is pre-formed in the polishing layer before the light-transmitting body is installed. This preliminary action creates a ready-to-receive structure that simplifies subsequent assembly, allowing the adhesive sealant to be easily applied and laterally fill the pre-defined gap without requiring complex manufacturing steps.
Solution Approach 2:
The adhesive sealant is applied in a manner that allows it to self-distribute and laterally fill the gap between the light-transmitting body and cavity walls. This self-filling capability reduces the need for precise manual application or complex dispensing equipment, simplifying manufacturing while ensuring complete gap coverage for maximum delamination resistance.
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 design enhances the stability and transparency of the window, reducing the risk of delamination and leakage, allowing for larger window sizes without increased delamination risk, and minimizes the risk of scratching during the polishing process, thereby improving endpoint detection accuracy and polishing uniformity.
Implementation Method 1
An adhesive sealant of a different second material is disposed in and laterally fills the gap
Implementation Method 2
A fluid-impermeable layer spans the aperture and the polishing pad
Implementation Method 3
The light-transmitting body is positioned in the aperture
Data Source
Figure 1~2
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Figure 7~9
AI summary
A polishing pad includes a polishing layer stack that has a polishing surface, a bottom surface, and an aperture from the polishing surface to the bottom surface. The polishing layer stack includes a polishing layer that has the polishing surface. A fluid- impermeable layer spans the aperture and the polishing pad. A first adhesive layer of a first adhesive material is in contact with and secures the bottom surface of the polishing layer to the fluid-impermeable layer. The first adhesive layer spans the aperture and the polishing pad. The light-transmitting body is positioned in the aperture and has a lower surface in contact with, is secured to the first adhesive layer, and is spaced apart from a side-wall of the aperture by a gap. An adhesive sealant of a different second material is disposed in and laterally fills the gap.