CMP Polishing Pad UV Endpoint Windows
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional CMP polishing pads with endpoint detection windows suffer from low transmittance at wavelengths below 400 nm and degradation upon exposure to UV light, leading to polishing defects and adhesion issues during conditioning.
Innovation Solution
A CMP polishing pad with endpoint detection windows made from a reaction mixture of a linear cycloaliphatic urethane macromonomer and an aliphatic initiator, providing improved UV transmittance and durability, and enabling rapid customization without skiving, using a composition with specific molecular weight ranges and cycloaliphatic dicarbamate groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer materials are used for endpoint detection windows, then the windows can be easily manufactured and installed, but they exhibit low transmittance at wavelengths below 400 nm and degrade upon UV light exposure
Solution Approach 1:
The patent changes the chemical composition parameters of the window material by using aliphatic polyurethane with specific molecular weight ranges (5,000-50,000 g/mol) and controlled aromatic ring density (0.5-2.0 mmol/g), which fundamentally alters the material's UV transmission properties and photostability while maintaining manufacturability
Solution Approach 2:
The patent creates a composite material system combining aliphatic polyurethane base polymer with specific additives and modifiers that achieve both high UV transmittance (>30% at 300-400 nm) and durability, resolving the contradiction between performance and ease of manufacture
2Manufacturing precision
If skiving is used to create window openings in molded polishing pads, then the windows can be precisely positioned, but the process is time-consuming and damages the window surface
Solution Approach 1:
The patent incorporates window openings directly into the mold during the original pad manufacturing process, so the windows are pre-formed and positioned accurately without requiring subsequent skiving or machining operations, thereby eliminating surface damage and improving productivity
Solution Approach 2:
The patent merges the window formation step with the pad manufacturing step by integrating window openings into the mold cavity, combining two previously separate operations into one simultaneous process that achieves both precision and high productivity
3Illumination intensity
If aliphatic polyurethane window materials are used to improve UV transmittance, then light transmission at 300-400 nm is enhanced, but the materials lack durability during CMP polishing pad conditioning
Solution Approach 1:
The patent optimizes specific parameters of the aliphatic polyurethane including molecular weight (5,000-50,000 g/mol), aromatic ring density (0.5-2.0 mmol/g), and incorporates crosslinking agents or reinforcing fillers that simultaneously enhance both UV transmittance and mechanical durability during conditioning processes
Solution Approach 2:
The patent develops a composite aliphatic polyurethane formulation combining the base polymer with strategic additives that provide both optical clarity for UV transmission and structural reinforcement for durability, resolving the contradiction between light transmission and strength
4Reliability
If individual windows are formed and placed into recesses in the pad, then window adhesion can be improved, but the process is time-consuming and may still result in adhesion problems
Solution Approach 1:
The patent pre-integrates window openings into the pad structure during molding, eliminating the need for separate window placement and adhesion processes, thereby achieving both reliable adhesion (through proper mold design) and time efficiency
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 achieves high UV transmittance at 300 to 400 nm, maintains durability during pad conditioning, and enhances adhesion between the window and pad, ensuring effective endpoint detection and reduced polishing defects.
Implementation Method 1
an aliphatic initiator, such as an aliphatic photoinitiator or an aliphatic thermal initiator
Implementation Method 2
an aliphatic initiator, such as an aliphatic photoinitiator or an aliphatic thermal initiator, such as azo-bis isobutyronitrile (AIBN)
Implementation Method 3
high UV transmittance at 300 to 400 nm
Data Source
AI summary
The present invention provides chemical mechanical (CMP) polishing pads for polishing a substrate chosen from a semiconductor substrate comprising the CMP polishing pad and having one or more endpoint detection windows which is the cured product of a reaction mixture of a linear cycloaliphatic urethane macromonomer having two (meth)acrylate endgroups bound via cycloaliphatic dicarbamate esters to a polyether, polycarbonate or polyester chain having an average molecular weight of from 450 to 2,000, or an cycloaliphatic urethane oligomer thereof, and an aliphatic initiator, wherein the total isocyanate content in the urethane macromonomer ranges from 3.3 to 10 wt. %, and, further wherein, the composition comprises less than 5 wt. % of unreacted (meth)acrylate monomer and is substantially free of unreacted isocyanate. Regardless of their hardness or lack thereof, the endpoint detection windows provide excellent durability when wet.