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Polishing composition

a technology of composition and polishing, applied in the field of polishing composition, can solve the problems of low polishing rate, easy formation of scratches, and severely affecting the surface quality of the polishing, and achieve the effect of reducing scratches

Inactive Publication Date: 2007-07-19
YOSHIDA HIROYUKI +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a polishing composition containing silica particles and an aqueous medium, where the silica particles have a negative zeta potential. The invention also includes methods for polishing glass substrates and memory hard disk substrates using the polishing composition, as well as methods for increasing the polishing rate and reducing scratches on the substrates. The technical effects of the invention include improved polishing efficiency and reduced damage to the substrate surface.

Problems solved by technology

Along with this trend, the surface qualities required after polishing have become severely assessed every year even in a method for manufacturing a substrate for a magnetic disk.
The slurry polishing liquid containing the silica particles has been highly useful and is widely used, but has a disadvantage that the polishing rate is low.
On the other hand, the slurry polishing liquid containing cerium oxide particles has been used for polishing optical glass, a memory hard disk made of glass, a semiconductor insulation film, or the like, and has a feature of a high polishing rate, but has a disadvantage that scratches tend to be easily formed.
However, although scratches and dust are reduced as compared to the case where the zeta potential of the surface of the particles exceeds −10 mV, the polishing rate is also lowered, so that both the reduction of scratches and dust and the increase in polishing rate cannot be satisfied.
However, the description of the polishing at a high speed is made on the basis of comparison with a polishing agent containing silica particles, which are heterogeneous particles, so that the relationship between the polishing rate and the zeta potential has not yet been elucidated.
However, the surface smoothness is still insufficient for obtaining surface smoothness required for high density of the memory hard disk substrate.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

examples

[0092] The following examples further describe and demonstrate embodiments of the present invention. The examples are given solely for the purposes of illustration and are not to be construed as limitations of the present invention.

[0093] Each of the polishing compositions in the following Examples and Comparative Examples was evaluated for its polishing properties by using an Ni—P plated, aluminum alloy substrate having a thickness of 1.27 mm, an outer circumferential diameter of 95 mm and an inner circumferential diameter of 25 mm, which was previously roughly polished with a polishing liquid containing alumina abrasives so that the substrate had a surface roughness (Ra) of 1 nm as an object to be polished.

examples i-1 to i-9

and Comparative Examples I-1 to I-5

[0094] There were added together Colloidal Silica I-A (commercially available from Du Pont, average primary particle size: 27 nm, D90 / D50=3.1), Colloidal Silica I-B (commercially available from Du Pont, average primary particle size: 15 nm, D90 / D50=2.2), Colloidal Silica I-C (commercially available from Du Pont, average primary particle size: 19 nm, D90 / D50=1.6), or a mixture of Colloidal Silicas I-A and I-B corresponding to Example I-4 (commercially available from Du Pont, average primary particle size: 18 nm, D90 / D50=3.0) as an abrasive; a 60% by weight aqueous HEDP solution, a 98% by weight sulfuric acid, and / or citric acid as a zeta potential controlling agent; and a 35% by weight aqueous hydrogen peroxide as the other component, to give each of the polishing compositions having a composition, pH, and a zeta potential of the abrasive as shown in Table 1. Here, the balance was ion-exchanged water.

[0095] The order of mixing each component was as...

example ii-1

[0126] There were added together 20% by weight of Colloidal Silica Slurry II-A (commercially available from Du Pont, average primary particle size: 37 nm, D90 / D50=2.2) as silica particles; 0.25% by weight of a 36% by weight aqueous hydrochloric acid solution as a zeta potential controlling agent, and the balance being ion-exchanged water to give a polishing composition (zeta potential: 26.5 mV, pH: 1.5).

[0127] The order of mixing each component was as follows: The zeta potential controlling agent 36% by weight aqueous hydrochloric acid solution prepared by diluting hydrochloric acid with water was added to Colloidal Silica Slurry II-A little by little while stirring, to give a polishing composition. The polishing properties were evaluated on the basis of the following conditions by using the polishing composition. As a result, the polishing rate was 0.197 μm / minute, and a surface smoothness (Ra) of 0.23 nm.

II-1. Substrate to be Polished

[0128] A memory hard disk substrate made of...

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Abstract

The present invention relates to a polishing composition containing an aqueous medium and silica particles, wherein the silica particles in the polishing composition has a zeta potential of from −15 to 40 mV; a method for manufacturing a substrate including the step of polishing a substrate to be polished with a polishing composition containing an aqueous medium and silica particles, wherein the silica particles in the polishing composition has a zeta potential of from −15 to 40 mV; and a method for reducing scratches on a substrate to be polished with a polishing composition containing an aqueous medium and silica particles, including the step of adjusting a zeta potential of silica particles in the polishing composition to −15 to 40 mV. The polishing composition can be favorably used in polishing the substrate for precision parts, including substrates for magnetic recording media such as magnetic discs, optical discs and opto-magnetic discs; photomask substrates; optical lenses; optical mirrors; optical prisms; semiconductor substrates; and the like.

Description

[0001] This application is a Divisional of co-pending application Ser. No. 11 / 081,560, filed on Mar. 17, 2005, the entire contents of which are hereby incorporated by reference and for which priority is claimed under 35 U.S.C. § 120.FIELD OF THE INVENTION [0002] The present invention relates to a polishing composition and a method for manufacturing a substrate. [0003] In addition, the present invention relates to a method for increasing a polishing rate of a substrate (hereinafter referred to as a “polishing rate-increasing method”), a method for manufacturing a substrate using the method, a polishing composition, and a method for reducing scratches. BACKGROUND OF THE INVENTION [0004] Currently, steps for polishing various substrates have been employed in the manufacture of various kinds of substrates. For example, in the field of semiconductors, there has been employed a step of polishing a silicon wafer substrate; a compound semiconductor wafer substrate made of a compound such as...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B24D3/02B24B7/30B24B1/00B24B7/24B24B37/04C09G1/02C09K3/14
CPCB24B37/044C09G1/02C09K3/1436C09K3/1463
Inventor YOSHIDA, HIROYUKIHOMMA, YUICHITAKASHIMA, SHIGEAKIHAGIHARA, TOSHIYA
Owner YOSHIDA HIROYUKI
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