Olefin Copolymer Window for CMP Pad UV Resistance
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Solution Overview
Problem
Conventional chemical mechanical polishing pads face issues with window leakage and degradation when exposed to shorter wavelengths of light, leading to variability in polishing properties and potential defects, and existing solutions do not adequately address durability and defectivity in multilayer configurations.
Innovation Solution
A multilayer chemical mechanical polishing pad with a broad spectrum endpoint detection window block made from an olefin copolymer, which is resistant to degradation and includes a pressure-sensitive adhesive layer to secure the polishing layer to the subpad without laminating adhesives, reducing window leakage and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional polymer based endpoint detection windows are used, then the pad allows light transmission for endpoint detection, but the windows degrade upon exposure to ultraviolet light (330-425 nm) causing yellowing and decomposition
Solution Approach 1:
The patent changes the chemical composition parameters of the window material by incorporating specific UV absorbers and Hindered Amine Light Stabilizers (HALS) at controlled concentrations (0.1-10 wt% UV absorber, 0.05-5 wt% HALS) to resist UV degradation while maintaining light transmission properties
Solution Approach 2:
The patent creates a composite window material by combining base polymer (polyurethane or polyacrylic) with UV stabilizing agents (UV absorbers and HALS), forming a multi-component system that provides both optical clarity and UV resistance
2Illumination intensity
If aliphatic polyurethane windows are used to improve light transmission, then broad spectrum transmission is achieved, but the windows lack durability for demanding polishing applications
Solution Approach 1:
The patent creates a composite window material by combining base polymer (polyurethane or polyacrylic) with UV stabilizing agents (UV absorbers and HALS), forming a multi-component system that provides both optical clarity and UV resistance
3Reliability
If filters are used to attenuate ultraviolet light before exposure to the window, then window degradation is reduced, but the ability to detect thinner material layers and smaller device sizes is compromised
Solution Approach 1:
The patent introduces UV stabilizing agents (UV absorbers and HALS) as intermediary substances within the window material itself, which absorb and dissipate UV energy before it can degrade the polymer structure, while allowing the desired UV wavelengths to pass through for endpoint detection
4Measurement precision
If plug in place windows are used in polishing pads, then endpoint detection is enabled, but polishing fluid leaks around the window into the porous subpad layer causing variability in polishing properties
Solution Approach 1:
The patent uses a flexible sealing member (O-ring or gasket) made of elastomeric material that conforms to the interface between the window and the polishing pad layers, creating an effective seal that prevents slurry leakage while accommodating dimensional variations and thermal expansion
Solution Approach 2:
The patent creates a composite sealing structure combining the rigid or semi-rigid window material with a flexible elastomeric sealing member, where each material provides its complementary properties (optical clarity and sealing flexibility)
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 solution provides a durable polishing pad with reduced spectrum loss and improved endpoint detection accuracy, minimizing defects and variability in polishing performance across the pad surface.
Implementation Method 1
the broad spectrum, endpoint detection window block exhibits a spectrum loss ≦60%
Implementation Method 2
a pressure sensitive adhesive layer; wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; wherein the coextensive region secures the polishing layer to the porous subpad layer without the use of a laminating adhesive
Data Source
AI summary
A multilayer chemical mechanical polishing pad is provided, having: a polishing layer having a polishing surface, a counterbore opening, a polishing layer interfacial region parallel to the polishing surface; a porous subpad layer having a bottom surface and a porous subpad layer interfacial region parallel to the bottom surface; and, a broad spectrum, endpoint detection window block comprising, comprises an olefin copolymer; wherein the window block exhibits a uniform chemical composition across its thickness; wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; wherein the multilayer chemical mechanical polishing pad has a through opening that extends from the polishing surface to the bottom surface of the porous subpad layer; wherein the counterbore opening opens on the polishing surface, enlarges the through opening and forms a ledge; and, wherein the window block is disposed within the counterbore opening.