Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2000-10-17
2002-10-08
Nguyen, George (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S060000, C051S307000, C252S062200, C510S165000
Reexamination Certificate
active
06461227
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention pertains to a method of planarizing or polishing a surface of a memory or rigid disk.
BACKGROUND OF THE INVENTION
The demand for increased storage capacity in memory or rigid disks and the trend towards miniaturization of memory or rigid disks (due to the requests of computer manufacturers for smaller hard drives) continues to emphasize the importance of the memory or rigid disk manufacturing process, including the planarization or polishing of such disks for ensuring maximal performance. While there exist several chemical-mechanical polishing (CMP) compositions and methods for use in conjunction with semiconductor device manufacture, few conventional CMP methods or commercially available CMP compositions are well-suited for the planarization or polishing of memory or rigid disks.
In particular, such polishing compositions and/or methods can result in less than desirable polishing rates and high surface defectivity when applied to memory or rigid disks. The performance of a memory or rigid disk is directly associated with its surface quality. Thus, it is crucial that the polishing compositions and methods maximize the polishing or removal rate yet minimize surface defectivity of the memory or rigid disk following planarization or polishing.
There have been many attempts to improve the removal rate of memory or rigid disks during polishing, while minimizing defectivity of the polished surface during planarization or polishing. For example, U.S. Pat. No. 4,769,046 discloses a method for polishing a nickel-plated layer on a rigid disk using a composition comprising aluminum oxide and a polishing accelerator such as nickel nitrate, aluminum nitrate, or mixtures thereof. There remains a need, however, for improved methods of planarizing or polishing memory or rigid disks at a high removal rate, while minimizing surface defectivity. The present invention seeks to provide such a method. These and other advantages of the present inventive method will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a method for planarizing or polishing a surface of a memory or rigid disk comprising (a) providing a polishing system comprising (i) a polishing composition comprising water, an oxidizing agent, and a complexing agent selected from the group consisting of ammonia, halide ions, and mixtures thereof, and (ii) a polishing pad and/or an abrasive, (b) contacting at least a portion of a surface of a memory or rigid disk with the polishing system, and (c) moving the polishing system relative to the memory or rigid disk to polish at least a portion of the surface of a memory or rigid disk.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a method for planarizing or polishing a surface of a memory or rigid disk through use of a polishing system. The polishing system comprises (i) a polishing composition comprising water, an oxidizing agent, and a complexing agent selected from the group consisting of ammonia, halide ions, an mixtures thereof, and (ii) a polishing pad and/or an abrasive. At least a portion of the surface of the memory or rigid disk is contacted with the polishing system, and the polishing system is moved relative to the memory or rigid disk to polish at least a portion of the surface of the memory or rigid disk.
The term “memory or rigid disk” refers to any magnetic disk, hard disk, rigid disk, or memory disk for retaining information in electromagnetic form. The memory or rigid disk typically has a surface that comprises nickel-phosphorus, but the memory or rigid disk surface can comprise any other suitable material.
The abrasive of the polishing system can be any suitable abrasive. The abrasive desirably is in the form of particles and desirably is a metal oxide (e.g., metal oxide particles). Metal oxide abrasives include, for example, alumina, silica, titania, ceria, zirconia, germania, magnesia, coformed products thereof, and mixtures thereof Preferably, the abrasive of the polishing system is a condensation-polymerized metal oxide (e.g, condensation-polymerized silica particles). Condensation-polymerized silica particles typically are prepared by condensing Si(OH)
4
to form colloidal particles. Such abrasive particles can be prepared in accordance with U.S. Pat. No. 5,230,833 or can be obtained as any of various commercially available products, such as the Akzo-Nobel Bindzil {fraction (50/80)} product and the Nalco 1050, 2327, and 2329 products, as well as other similar products available from DuPont, Bayer, Applied Research, Nissan Chemical, and Clariant.
It should be understood that the polishing or planarization of a memory or rigid disk can involve two or more distinct polishing steps, utilizing different polishing systems, or alternatively utilizing substantially similar, or even the same, polishing systems. It is suitable, for example, to utilize in a first polishing step a “coarse” polishing system comprising abrasive particles with a particle size greater than 100 nm, and to utilize in a second polishing step a “fine” polishing system comprising abrasive particles with a particle size less than 100 nm.
The abrasive particles of the polishing system of the present invention, especially when formulated as a “fine” polishing system, desirably are such that about 90% or more of the abrasive particles (by number) have a particle size no greater than 100 nm. Preferably, the abrasive particles are such that at least about 95%, 98%, or even substantially all (or actually all) of the abrasive particles (by number) have a particle size no greater than 100 nm. These particle size preferences for the abrasive particles (i.e., whereby at least about 90%, 95%, 98%, substantially all, and all of the abrasive particles (by number) are no greater than a specific size of abrasive particle) also can pertain to other particle sizes, such as 95 nm, 90 nm, 85 nm, 80 nm, 75 nm, 70 nm, and 65 nm.
Similarly, the abrasive can be such that at least about 90%, 95%, 98%, or even substantially all (or actually all) of the abrasive particles (by number) have a particle size no less than 5 nm. These particle size preferences for the abrasive particles (i.e., whereby at least about 90%, 95%, 98%, substantially all, and all of the abrasive particles (by number) are no less than a specific size of abrasive particle) also can pertain to other particle sizes, such as 7 nm, 10 nm, 15 nm, 25 nm, and 30 nm.
The percentage values used herein to describe the nature of the abrasive in terms of particle size are percentages “by number,” rather than being weight percentages, unless otherwise noted. The particle size of the abrasive refers to the particle diameter. The particle size can be measured by any suitable technique. The particle size values set forth herein are based on a visual inspection, specifically by way of transmission electron micrography (TEM), of a statistically significant sample of the abrasive particles, preferably at least 200 particles.
The particle size distribution of the abrasive can be characterized by geometric standard deviation by number, referred to as sigma-g (&sgr;
g
). The &sgr;
g
values can be obtained by dividing (a) the diameter at which 84% of the abrasive particles (by number) are less than by (b) the diameter at which 16% of the abrasive particles (by number) are less than (i.e., &sgr;
g
=d
84
/d
16
). Monodispersed abrasive particles have a &sgr;
g
value of about 1. As the abrasive particles become polydispersed (i.e., include particles of increasingly different size), the &sgr;
g
value of the abrasives particles increases above 1. Although the abrasive particles suitable for use in conjunction with the present invention can be mono or poly dispersed to any degree, the abrasive particles typically have a &sgr;
g
value of about 2.5 or less (e.g., about 2.3 or less). The abrasive particles desirably have a &sgr;
g
value of at least about 1.1 (e.g., about 1.1-2.3), preferably a &sgr;
g
value of at least about 1.3 (e.g
Cabot Microelectronics Corporation
Nguyen George
LandOfFree
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