Method for polishing a memory or rigid disk with an amino...

Details Method for polishing a memory or rigid disk with an amino... Method for polishing a memory or rigid disk with an amino...

2000-04-04

2002-10-29

Kunemund, Robert (Department: 1765)

Etching a substrate: processes

Nongaseous phase etching of substrate

Using film of etchant between a stationary surface and a...

C216S038000, C216S088000, C216S103000, C438S692000, C438S693000, C252S299010, C252S079100, C252S079400, C451S036000

Reexamination Certificate

active

06471884

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of planarizing or polishing a substrate, particularly 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 rigid or memory 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 of planarizing or polishing the surface of a memory or rigid disk comprising abrading at least a portion of the surface with (i) a polishing composition comprising an oxidizing agent selected from the group consisting of persulfates and peroxides, an amino acid, and water, and (ii) an abrasive.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a method of planarizing or polishing a memory or rigid disk. The method comprises contacting the surface of a memory or rigid disk with (i) a polishing composition comprising an oxidizing agent selected from the group consisting of persulfates and peroxides, an amino acid, and water, and (ii) an abrasive, and abrading at least a portion of the surface of the memory or rigid disk by movement of the polishing composition relative to the memory or rigid disk. Such contacting and abrading can take place by any suitable technique. For example, the polishing composition can be applied to the surface of the memory or rigid disk and used to abrade at least a portion of the surface of the memory or rigid disk through use of a polishing pad.
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 can be any suitable abrasive. Desirably, the abrasive is a metal oxide abrasive. Metal oxide abrasives include, for example, alumina, silica, titania, ceria, zirconia, germania, magnesia, and combinations thereof. Preferably, the abrasive of the present inventive method is a condensation-polymerizedmetal oxide, e.g., condensation-polymerizedsilica. Condensation-polymerizedsilica typically is prepared by condensing Si(OH)
4
to form colloidal particles. Such an abrasive 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 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.
The abrasive desirably is such that about 90% or more of the abrasive particles (by number) within the abrasive 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) within the abrasive 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) within the abrasive 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 particles of the abrasive (by number) within the abrasive 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) within the abrasive 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 particles within 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, preferably at least 200 particles.
The particle size distribution of the abrasive particles within 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) within the abrasive 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 &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. 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 (e.g., 1.1-1.3), preferably a &sgr;
g
value of at least about 1.3 (e.g., about 1.5-2.3 or even about 1.8-2.3).
Any suitable amount of the abrasive can be present in the polishing composition. Preferably, the abrasive is present in a concentration of about 0.1-30 wt. % of the composition, e.g., about 1-28 wt. % of the composition. More preferably, the abrasive is present in a concentration of about 3-25 wt. % of the composition, e.g., about 5-20 wt. % of the composition, or even about 6-15 wt. % of the composition. Alternatively, the abrasive, in whole or in part, can be fixed (e.g., embedded) on or in the polishing pad.
The oxidizing agent can be any suitable oxidizing agent. Suitable oxidizing agents include, for example, persulfates and peroxides. Preferably, the oxidizing agent is selected from the group consisting of ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide.
Any suitable amount of the oxidizing agent can

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