CMP Slurry for Nickel-Phosphorus Edge Roll-Off
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Solution Overview
Problem
Conventional chemical-mechanical polishing (CMP) methods and compositions are inadequate for effectively planarizing or polishing memory or rigid disks, leading to issues with microwaviness and edge roll-off, which affect the flying height of magnetic heads and data recording performance.
Innovation Solution
A CMP composition comprising wet-process silica particles, a water-soluble polymer, an oxidizing agent, a chelating agent, and an aqueous carrier with a pH of 1 to 7, which includes alpha alumina and fumed alumina particles, and a water-soluble polymer that aggregates silica to encapsulate alumina, improving surface smoothness and reducing edge roll-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high downward force is applied to increase removal rate, then productivity improves, but surface roughness deteriorates due to abrasive particle embedding
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by introducing an oxidizing agent that converts metallic abrasives to oxide forms, and adjusts pH to control the polishing reaction. This allows effective material removal while preventing abrasive embedding that degrades surface roughness.
Solution Approach 2:
The patent uses a composite polishing system combining metallic abrasive particles with oxidizing agents and pH-adjusting components. This composite composition enables controlled material removal through chemical-mechanical action while maintaining surface integrity and preventing abrasive embedding.
2Productivity
If conventional CMP methods are used to increase removal rate, then productivity improves, but manufacturing precision deteriorates due to microwaviness and edge roll-off
Solution Approach 1:
The patent modifies the chemical parameters of the polishing environment by adding oxidizing agents and pH-adjusting components to the slurry. These parameter changes enable uniform material removal across the disk surface, preventing microwaviness and edge roll-off while maintaining high removal rates.
Solution Approach 2:
The patent replaces purely mechanical abrasion with a chemical-mechanical polishing process. The oxidizing agent chemically modifies the substrate surface, making it more susceptible to controlled removal, thereby reducing reliance on high mechanical pressure that causes microwaviness and edge effects.
3Productivity
If high removal rate is achieved through increased downward force, then productivity improves, but reliability deteriorates due to head-to-disk collision risk from microwaviness
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing slurry by incorporating oxidizing agents and pH-adjusting components. This enables uniform material removal that minimizes microwaviness, ensuring stable head-to-disk spacing and preventing collisions while maintaining high removal rates.
Solution Approach 2:
The patent substitutes mechanical pressure-based removal with chemical-mechanical polishing. The oxidizing agent facilitates controlled material removal at lower pressures, producing a smoother surface that eliminates microwaviness-induced spacing modulation and prevents head-to-disk collisions.
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 effectively minimizes microwaviness and edge roll-off while maintaining a high removal rate, enhancing the surface finish of memory or rigid disks and improving data recording accuracy and reliability.
Implementation Method 1
a chemical-mechanical polishing composition comprising (a) an abrasive comprising wet-process silica particles, (b) a water-soluble polymer, (c) an oxidizing agent
Implementation Method 2
contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; and moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate, such as the nickel phosphorus layer on a surface of the substrate, to abrade at least a portion of the substrate
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition including (a) an abrasive comprising wet-process silica particles, (b) a water-soluble polymer, (c) an oxidizing agent, (d) a chelating agent, (e) a pH-adjusting agent, and (f) an aqueous carrier, wherein the pH of the polishing composition is about 1 to about 7. The invention also provides a method of polishing a substrate, especially a nickel-phosphorus substrate, with the polishing composition.