Fluoropolymer Polyurea Polishing Pad for Faster 3D NAND CMP
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Solution Overview
Problem
Current Chemical Mechanical Planarization (CMP) processes for 3D NAND manufacturing are bottlenecked by slow removal rates, particularly during the Pre-Metal Dielectric (PMD) step, due to limitations in existing polishing pad technologies and slurries, which hinder the ability to efficiently planarize thick films in high-capacity memory devices.
Innovation Solution
Development of a polyurea polishing pad with a soft and hard phase matrix, incorporating fluorine-containing copolymers that remain hydrophilic during polishing, enhancing ceria slurry interactions and increasing removal rates without altering the pad's composition or introducing negative effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dielectric CMP slurries and polishing pads are used, then the CMP process can be performed, but the removal rate is too slow (250 nm/min) for efficient PMD planarization in 3D NAND manufacturing
Solution Approach 1:
The patent modifies the polishing pad's chemical composition by incorporating fluorine-containing copolymers (at least 5 wt% of the top pad layer) with specific molecular weight ranges (1,000-10,000) and fluorine content (1-10 wt%). These parameter changes in the pad's polymer structure enhance its interaction with ceria slurry particles, increasing the Preston coefficient and achieving removal rates of 300-500 nm/min, thereby reducing CMP process time for PMD planarization.
Solution Approach 2:
The patent creates a composite polishing pad structure by combining fluorine-containing copolymers with conventional polyurethane or polyurea matrices. This composite material approach leverages the unique properties of fluorinated polymers (enhanced slurry interaction, hydrophilicity under shear) while maintaining the structural integrity and mechanical properties of the base polymer, resulting in a pad that achieves 20-30% higher removal rates without compromising pad performance.
2Productivity
If the polishing pad composition is altered to increase removal rate, then productivity improves, but the pad may lose hydrophilicity under shear conditions which is essential for slurry conveyance
Solution Approach 1:
The patent carefully selects specific parameters for the fluorine-containing copolymer: molecular weight (1,000-10,000), fluorine content (1-10 wt%), and composition (at least 5 wt% of top pad layer). These parameter optimizations ensure that the copolymer enhances slurry interaction and removal rate while maintaining adequate hydrophilicity under shear conditions, balancing productivity with reliable slurry conveyance.
Solution Approach 2:
The fluorine-containing copolymer is incorporated into the top pad layer (specifically at least 5 wt% of this layer) rather than uniformly throughout the entire pad structure. This localized quality enhancement concentrates the slurry-interaction-enhancing properties at the polishing surface where they are most needed, while the bulk pad material retains its base polymer's hydrophilic characteristics for reliable slurry conveyance.
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 polyurea polishing pad achieves a 20-30% increase in removal rate with ceria particles and improved thermal stability, while maintaining hydrophilicity under shear conditions, thus addressing the slow CMP process times and enhancing the efficiency of the PMD step in 3D NAND manufacturing.
Implementation Method 1
the soft segments forming a fluorine rich phase that concentrates adjacent the polymeric microelements and at the polishing layer during polishing
Implementation Method 2
wherein the polishing layer remains hydrophilic during polishing in shear conditions
Implementation Method 3
the polyurea matrix being cured with the curative agent and including gas or liquid-filled polymeric microelements
Implementation Method 4
the hard phase is precipitated within the soft phase
Data Source
AI summary
The invention provides a polishing pad suitable for polishing at least one of semiconductor, optical, magnetic or electromechanical substrates. The polishing pad includes a polyurea polishing layer and a polyurea matrix. The polyurea matrix has a soft phase and a hard phase. The soft phase is formed from soft segments and the hard phase is formed from diisocyanate hard segments and a curative agent. The soft segment areva copolymer of aliphatic fluorine-free polymer groups and a fluorocarbon having a length of a least six carbons. The polyurea matrix is cured with the curative agent and includes gas or liquid-filled polymeric microelements. The soft segments form a fluorine rich phase that concentrates adjacent the polymeric microelements and at the polishing layer during polishing. The polishing layer remains hydrophilic during polishing in shear conditions.