CMP Pad with MCDEA Curative for 3D Substrate Planarization
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) pads are inadequate for effectively polishing three-dimensional semiconductor or memory substrates with thick oxide films and large features, as they fail to provide the necessary removal rates and planarization for substrates with dimensions greater than previous generations.
Innovation Solution
A CMP polishing pad with a polyurethane reaction product comprising 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) or mixtures with 4,4′-methylene-bis-o-(2-chloroaniline) (MbOCA) and a polyisocyanate prepolymer, formed from polytetramethylene ether glycol (PTMEG) or polypropylene glycol (PPG), having a specific unreacted isocyanate concentration and stoichiometric ratio, which provides a high shear storage modulus and low damping component for enhanced planarization and removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP pads are used, then polishing process is simple, but removal rate is insufficient for thick oxide films
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing pad by incorporating specific curatives (MCDEA, MbOCA) and controlling the unreacted isocyanate content (8.6-11 wt.%), stoichiometric ratio (0.85:1 to 1.20:1), and shear storage modulus (125-500 MPa at 65°C) to achieve both high removal rate and effective polishing of thick oxide films
Solution Approach 2:
The patent uses composite polyurethane materials formed by reacting polyisocyanate prepolymer with specific curatives (MCDEA, MbOCA) to create a polishing pad with optimized mechanical and chemical properties that simultaneously provides high removal rate and reliable polishing performance for three-dimensional substrates
2Manufacturing precision
If conventional CMP pads are used, then pad material is standard, but planarization capability is insufficient for large features
Solution Approach 1:
The patent optimizes physical parameters including shear storage modulus (125-500 MPa at 65°C), damping component (low), and Shore D hardness (60-90) to enable the polishing pad to maintain structural integrity and provide uniform pressure distribution across large feature dimensions (1-50 mm), achieving excellent planarization quality for complex three-dimensional substrate geometries
Solution Approach 2:
The patent creates local quality variations in the polishing pad through controlled porosity (8-40%) and optimized material distribution to adapt to different regions of large-scale substrates, ensuring consistent planarization performance across varying feature sizes and depths
3Productivity
If polyurethane prepolymer from polypropylene glycol and toluene diisocyanate is used, then metal containing substrates are polished improved, but removal rate for oxide films is insufficient
Solution Approach 1:
The patent changes the chemical composition by incorporating specific curatives (MCDEA, MbOCA) and controlling the unreacted isocyanate content (8.6-11 wt.%) to enhance reactivity with oxide films while maintaining compatibility with metal-containing substrates, achieving both high removal rate and broad substrate adaptability
Solution Approach 2:
The patent creates a composite polyurethane system combining polyisocyanate prepolymer with specific curatives to achieve dual functionality: high removal rate for thick oxide films and effective polishing for metal-containing substrates, expanding the range of applicable substrate types
Data Source
AI summary
The present invention provides a chemical mechanical (CMP) polishing pad for polishing three dimensional semiconductor or memory substrates comprising a polishing layer of a polyurethane reaction product of a thermosetting reaction mixture of a curative of 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) or mixtures of MCDEA and 4,4′-methylene-bis-o-(2-chloroaniline) (MbOCA), and a polyisocyanate prepolymer formed from one or two aromatic diisocyanates, such as toluene diisocyanate (TDI), or a mixture of an aromatic diisocyanate and an alicyclic diisocyanate, and a polyol of polytetramethylene ether glycol (PTMEG), polypropylene glycol (PPG), or a polyol blend of PTMEG and PPG and having an unreacted isocyanate (NCO) concentration of from 8.6 to 11 wt. %. The polyurethane in the polishing layer has a Shore D hardness according to ASTM D2240-15 (2015) of from 60 to 90, a shear storage modulus (G′) at 65° C. of from 125 to 500 MPa, and a damping component (G″/G′ measured by shear dynamic mechanical analysis (DMA), ASTM D5279-08 (2008)) at 50° C. of from 0.06 to 0.13.