Nickel-Phosphorus Disk Polishing Composition
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Solution Overview
Problem
The demand for improved planarization and polishing of memory or rigid disks with reduced chemical oxygen demand in polishing compositions, due to increased storage capacity needs and environmental regulations, is not adequately met by conventional chemical-mechanical polishing methods.
Innovation Solution
A chemical-mechanical polishing composition comprising alpha alumina, fumed alumina, silica, an oxidizing agent that oxidizes nickel-phosphorous, oxalic acid, optionally tartaric acid, a nonionic surfactant, a biocide, and water, with a pH of 2 to 4, is used to polish substrates, reducing chemical oxygen demand and enhancing surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP compositions are used for polishing memory or rigid disks, then polishing capability is provided, but chemical oxygen demand increases and environmental compliance becomes difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the CMP slurry by using oxalic acid (0.1-5 wt%) and tartaric acid (0.1-2 wt%) instead of conventional organic additives, maintaining polishing effectiveness while reducing chemical oxygen demand to meet environmental standards
Solution Approach 2:
The patent employs readily available, biodegradable organic acids (oxalic acid and tartaric acid) that provide the necessary chemical activity for polishing but are environmentally friendly and easily disposed of, replacing complex synthetic organic additives
2Productivity
If the flying height of the magnetic head is decreased to improve recording density, then storage capacity increases, but the requirement for surface planarity becomes more stringent
Solution Approach 1:
The patent uses a composite polishing system combining multiple abrasive types (alpha alumina, fumed alumina, silica) with specific size distributions and chemical additives that work synergistically to achieve superior surface planarity and finish quality
Solution Approach 2:
The patent employs abrasives with different size ranges (0.01-10 micrometers) to address different surface defects at various scales, with finer particles filling in micro-irregularities while larger particles remove broader surface deviations
3Volume of moving object
If miniaturization of memory or rigid disks is pursued to increase storage capacity, then device size decreases, but the polishing process complexity increases
Solution Approach 1:
The patent develops a universal CMP composition formulation that can effectively polish various disk sizes and nickel-phosphorous layer thicknesses, eliminating the need for different polishing recipes for different form factors
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 polishing composition effectively improves the surface finish and planarity of memory or rigid disks while reducing chemical oxygen demand, thus meeting environmental and performance requirements.
Implementation Method 1
an oxidizing agent that oxidizes nickel-phosphorous
Implementation Method 2
abrading at least a portion of the substrate to polish the substrate
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising alpha alumina, fumed alumina, silica, an oxidizing agent that oxidizes nickel-phosphorous, oxalic acid, optionally, tartaric acid, optionally, a nonionic surfactant, optionally, a biocide, and water. The invention also provides a method of chemically-mechanically polishing a substrate comprising contacting a substrate with a polishing pad and the chemical-mechanical polishing composition, moving the polishing pad and the polishing composition relative to the substrate, and abrading at least a portion of the substrate to polish the substrate.