JPH059463A - Abarasive composition for metallic material - Google Patents

Abstract

PURPOSE:To enable precision polishing of a metallic material used for a magnetic disc base a semiconductor substrate, etc., at a high processing efficiency with a low surface roughness and very few surface defects. CONSTITUTION:The title compsn. comprises water, an abrasive alumina, and a polishing accelerator consisting of at least one compd. selected from the group consisting of chromium (III) nitrate, lanthanum nitrate, ammonium cerium (III) nitrate, and neodymium nitrate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polishing composition for metal materials. More specifically, the present invention relates to a polishing composition used for precision polishing of magnetic disk substrate materials such as aluminum and nickel-based alloys, semiconductor substrate materials such as silicon and gallium arsenide, and other metal materials.

[0002]

2. Description of the Related Art Along with the progress of electronics and computer industries, precision polishing of magnetic disk substrate materials such as aluminum and nickel-based alloys and metal materials such as semiconductor substrate materials such as silicon and gallium arsenide is very important technology. Is positioned as.

In recent years, magnetic disks and semiconductors have higher recording densities and integration densities, and even in the precision polishing of these substrate materials, the surface smoothness and defect-free (scratch, orange peel, pit, The requirement level for no nodules) is becoming more sophisticated. Therefore, the improvement of the precision polishing technology level has become a more important issue than ever before.

Conventionally, lapping and polishing using free abrasive grains (abrasives) have been performed for a long time as a processing method with high accuracy. Alumina, silica, cerium oxide, zirconium oxide, iron oxide, chromium oxide, Silicon carbide, diamond and the like have been used as abrasive grains. Among them, alumina is widely used as an abrasive for metal materials such as magnetic disk substrate materials and semiconductor substrate materials because alumina has high hardness, excellent polishing ability, and is an easily available material.

Further, the surface smoothness of the processed surface in the precision polishing processing of the magnetic disk substrate material and the semiconductor substrate material,
From the viewpoint of improving the polishing rate, an invention has been proposed in which a specific polishing accelerator is blended in addition to water and an alumina abrasive.

For example, Japanese Examined Patent Publication (Kokoku) No. 64-436 discloses a polishing composition for neutral or weakly acidic plastic products and memory hard disks using nickel sulfate as a polishing accelerator. The publication discloses a polishing composition for a memory hard disk containing a polishing accelerator such as nickel nitrate or aluminum nitrate.

When nickel sulfate or nickel nitrate is used as a polishing accelerator, the pH is neutral or weakly acidic,
It has a defect that the polishing efficiency is not sufficient and surface defects such as minute pits and nodules are likely to occur. When aluminum nitrate is used as a polishing accelerator, the polishing efficiency is higher than that of nickel sulfate or nickel nitrate, but the pH is 2-4.
Since it is strongly acidic, it has poor workability and has the drawback of corrosion of polishing equipment.

In addition, with respect to the surface smoothness of the polished surface, it is the present situation that even if any of these polishing accelerators is used, it is not possible to meet the demanding level of sophistication, so that the polishing efficiency is higher and the surface smoothness is higher. There is a need for a polishing composition that provides a good polished surface.

[0009]

In view of such circumstances, the present inventors have aimed to obtain a polishing composition of a metal material, which has a high polishing efficiency, a small surface roughness and a polished surface without surface defects. As a result of earnest studies, it was found that when a specific polishing accelerator was contained, a polishing composition of a metal material satisfying all the above objects was obtained, and the present invention was completed.

[0010]

Means for Solving the Problems That is, the present invention provides a metal material polishing composition comprising water, an alumina abrasive and a polishing accelerator, wherein the polishing accelerator is chromium (III) nitrate, lanthanum nitrate, Another object of the present invention is to provide a polishing composition for a metal material, which is at least one selected from cerium (III) ammonium nitrate and neodymium nitrate.

The present invention will be described in more detail below. In the present invention, as the polishing accelerator, at least one compound selected from chromium (III) nitrate, lanthanum nitrate, ammonium cerium (III) nitrate, and neodymium nitrate is used. (III after the metal compound represents the valence of the metal.)

Of these, when chromium (III) nitrate is used as a polishing accelerator, a polishing composition in the acidic region having a pH of 2 to 4 is obtained as in the case of using conventionally known aluminum nitrate. The polishing rate and surface smoothness are superior to those when aluminum nitrate is used.

When at least one compound selected from lanthanum nitrate, cerium (III) ammonium nitrate and neodymium nitrate is used as a polishing accelerator, it is weakly acidic or neutral at pH 5 to 7, And polishing speed,
A polishing composition having excellent surface smoothness can be obtained.

The content of the polishing accelerator in the polishing composition is
About 0.3 to about 10% by weight, preferably about 0.5 to about 5
% By weight. The content of polishing accelerator is about 0.3% by weight
If it is less than the above range, the polishing rate tends to decrease and surface defects such as pits and nodules are likely to occur. On the other hand, even if the content of the polishing accelerator exceeds about 10% by weight, the polishing promoting effect is not improved, and the burden of wastewater treatment is increased.

The alumina abrasive used in the present invention is α-alumina, which is obtained by calcining alumina hydrate such as boehmite at 1100 ° C. to 1400 ° C. for 2 to 3 hours and then subjecting it to dry or wet vibration. A mill, a ball mill, an attritor, a bead mill, or the like, or a dry high-speed rotary mill or a known fine pulverizer such as an air flow pulverizer is used for pulverization. In addition, if necessary, wet gravity sedimentation, centrifugal sedimentation,
Coarse particles may be classified by a dry air classifier, and the particles may be sized to a desired particle size before use.

The content of the alumina abrasive in the polishing composition is about 1% by weight to about 30% by weight, preferably about 2% by weight to about 25% by weight. The content of alumina abrasive is
When it is less than about 1% by weight, the polishing efficiency is lowered, while when it exceeds about 30% by weight, no improvement in polishing efficiency is observed.
There is an inconvenience that the viscosity increases and the workability deteriorates.

The average particle size of the alumina abrasive is about 0.2.
To about 5μ, preferably about 0.3 to about 3μ. If the average particle size is less than about 0.2 μ, the polishing efficiency tends to be low, and fine particles tend to agglomerate to cause defects such as orange peel, and if it exceeds about 5 μ, the surface smoothness of the polished surface may deteriorate. It causes inconvenience.

In the polishing composition of the present invention, if necessary, celluloses such as cellulose, carboxymethyl cellulose and hydroxyethyl cellulose, and water-soluble polymers such as polyvinyl alcohol are used as anti-settling agents, and fatty acid esters and A surfactant such as funnel oil can also be added as a lubricant.

Although the mechanism of action of the polishing accelerator in the present invention is not clear, it has a mechanochemical polishing action on the polishing surface, and an action for controlling the dispersion and aggregation state of the alumina abrasive in the polishing composition. It is presumed that the metal material has an advantageous effect on the precision polishing process.

The polishing composition of the present invention is used for precision polishing of metal materials, and is particularly suitable for precision polishing of magnetic disk substrates plated with nickel-based alloys.

[0021]

The polishing composition of the present invention described in detail above is
Similar to the case of using the conventional polishing composition, between the workpiece and the polishing pad sliding on the surface thereof, only by using the polishing composition of the present invention, the processing efficiency is high, the surface roughness is small. It enables precision polishing of metal materials such as magnetic disk substrates and semiconductor substrates with extremely few surface defects, and its industrial value is enormous.

[0022]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the present invention, the analysis was carried out by the following method.

Average particle diameter: Measurement was carried out by a light scattering method particle size distribution measuring instrument Microtrac SPA.

Surface roughness: Surf coder E made by Kosaka Laboratory
The T-30HK was used to measure with a 0.5 μR stylus stylus at a measurement length of 0.8 mm and a cutoff of 80 μ.

Surface observation: The presence or absence of surface defects such as micro scratches, pits and nodules on the polished surface was observed by a differential interference microscope (50 times, 400 times).

Polishing speed: The weight of the workpiece before and after polishing was measured, and the polished thickness was calculated from the specific gravity of the substance to be polished.

Example 1 As a workpiece, an electroless Ni-P plated aluminum magnetic disk substrate (outer diameter 3.5 inch, Ni-P plated layer thickness 17 μ, surface roughness Ra 0.02 before polishing).
μ, Rmax 0.30 μ) was subjected to double-side polishing using a 4-way double-sided polishing machine (plate diameter 640 mmφ). As the polishing pad, a suede type pad (Domitex 25-6, manufactured by Daiichi Race Co., Ltd.) was used, the lower platen rotation speed was 40 rpm, and the processing pressure was 125.
Polishing was performed under the condition of g / cm ² .

The abrasive composition has an average particle size of 0.6 in pure water.
8.6% by weight of alumina abrasive, and 0.8% by weight of chromium (III) nitrate [Cr (NO ₃ ) ₃ .9H ₂ O] as a polishing accelerator were added and suspended to form a slurry. Then, polishing was performed for 5 minutes while supplying this slurry between the disk and the polishing pad at 40 ml / min. After polishing, the polishing rate, the surface roughness of the polished surface, and the polished surface were observed. The results are shown in Table 1.

Examples 2-5, Comparative Examples 1-3 The same procedure as in Example 1 was repeated except that the polishing composition in which the polishing accelerator was replaced by the polishing accelerator shown below was used in the method of Example 1. An aluminum magnetic disk substrate plated with electroless Ni-P was polished. The results are shown in Table 1. [Each example, the addition amount and the kind of the polishing accelerator used in Comparative Example (wt%)] Example _{2; La (NO 3) 3} · 6H 2 O 0.8 wt% Example 3; La (NO ₃ ) ₃ · 6H ₂ O 1.5 wt% example _{4; Ce (NO 3) 3} · 2 (NH 4 · NO 3) · 4H 2 O 0.8 wt% example _{5; Nd (NO 3) 3} · 6H ₂ O 0.8 wt% Comparative example _{1; Al (NO 3) 3} · 9H 2 O 0.8 wt% Comparative example _{2; NiSO 4 · 6H 2 O} 0.8 wt% Comparative example 3; None ─── ─

[0030]

[Table 1]

Claims (3)

[Claims] 1. A polishing composition for a metal material comprising water, an alumina abrasive and a polishing accelerator, wherein the polishing accelerator is chromium (III) nitrate, lanthanum nitrate, cerium ammonium nitrate (III) and neodymium nitrate. A polishing composition for a metal material, which is at least one selected from the above. 2. A polishing accelerator content of 0.3% by weight to 1
The composition for polishing a metal material according to claim 1, which is 0% by weight. 3. The content of alumina abrasive is 1% by weight to 3%.
The composition for polishing a metal material according to claim 1, which is 0% by weight.