JP2009245580A - Polishing liquid composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing liquid composition with which abrasive grains and polishing residues produced during polishing scarcely remain on a polished substrate after the finish of polishing, which has high polishing speed, and with which the smoothness of the substrate is maintained, and to provide a method of manufacturing the substrate for which the polishing liquid composition is used. <P>SOLUTION: The method of manufacturing the substrate for a hard disk has steps to supply the polishing liquid composition comprising an organic nitrogen compound having two or more amino groups and/or imino groups in the molecule, an organic polybasic acid, an abrasive, and water to the substrate, and to polish the substrate by using a polishing pad. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing liquid composition and a method for producing a substrate using the polishing liquid composition.

  In recent years, hard disks have been required to reduce the flying height of the magnetic head and prevent surface defects (surface contamination) in order to reduce the minimum recording area and increase the capacity.

  Therefore, conventionally, a polishing liquid that can polish the surface of the hard disk substrate more smoothly and hardly causes surface defects during polishing has been studied (for example, Patent Document 1). Recently, in order to obtain a substrate having a desired surface quality for a certain period of time, studies using two or more stages of polishing processes have been made.

  However, if the abrasive grains and polishing residue used in the hard disk substrate obtained in the first stage polishing process remain, most of them are removed in the second stage polishing process. Anything left unremoved becomes a defect. Further, although it is removed in the second stage polishing process, the residual abrasive grains and polishing residue in the first stage adversely affect the second stage polishing process and cause scratches and pits, which is not preferable. This is especially true in polishing performed in only one stage or polishing performed in the final finishing process.

  In order to solve these problems, it is important that abrasive grains and polishing debris are removed from the substrate at the end of the polishing process performed in each stage, but the polishing composition with less surface contamination of the substrate There has been almost no examination of things, and no one has yet been known that sufficiently solves this problem.

JP 2002-164307 A

  An object of the present invention is to provide a polishing composition that has little residue on a polishing substrate after polishing of abrasive grains and polishing residue generated in polishing, has a high polishing rate, and can maintain the smoothness of the substrate, and It is providing the manufacturing method of the board | substrate using this polishing liquid composition.

That is, the gist of the present invention is as follows.
[1] A polishing composition comprising an organic nitrogen compound having two or more amino groups and / or imino groups in the molecule, an organic polybasic acid, an abrasive, and water is supplied to a substrate, and a polishing pad is prepared. A method for producing a substrate for a hard disk, comprising a step of polishing the substrate used;
[2] The organic nitrogen compound is selected from the group consisting of polyalkyleneimines, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, bis (3-aminopropyl) amine, and 1,3-propanediamine. The production method according to the above,
[3] The production method according to [2], wherein the polyalkyleneimines have a molecular weight of 150 to 2000.
[4] The above [1] to [3], wherein the organic polybasic acid is selected from the group consisting of succinic acid, citric acid, malic acid, tartaric acid, hydroxyethylidene-1,1-diphosphonic acid, and ethylenediaminetetramethylenephosphonic acid. Any one of the production methods,
[5] The method according to any one of [1] to [4], wherein the content of the organic nitrogen compound is 0.001 to 0.5% by weight,
[6] The production method according to any one of [1] to [5], wherein the content of the polybasic acid is 0.002 to 20% by weight,
[7] Any of [1] to [6] above, wherein the weight ratio of the organic nitrogen compound to the organic polybasic acid (organic nitrogen compound / organic polybasic acid) is 1/10000 to 1/1. Or manufacturing method according to
[8] The production method according to any one of [1] to [7], wherein the content of the abrasive is 0.05 to 40% by weight,
[9] The method according to any one of [1] to [8], wherein the pH is 1 to 7,
[10] The production method according to any one of [1] to [9], wherein the polishing pressure is 2 to 30 kPa,
[11] The method according to any one of [1] to [10], wherein the polishing liquid composition is supplied to the substrate at a rate of 0.01 to 0.5 mL / min per 1 cm ^{2 of the} substrate to be polished.

  By using the polishing composition of the present invention, there is an effect that a substrate having few surface defects (surface contamination) and excellent surface smoothness can be efficiently produced.

  As described above, the polishing liquid composition of the present invention contains an organic nitrogen compound having two or more amino groups and / or imino groups in the molecule, an organic polybasic acid, an abrasive, and water. There are characteristics, and by having such characteristics, there is an effect that it is possible to efficiently manufacture a substrate with few surface defects (surface contamination) and excellent surface smoothness.

In addition, although it is still unclear about the action mechanism for preventing the abrasive grains and polishing residue of the polishing composition of the present invention from remaining, a specific organic nitrogen compound and an organic polybasic acid are used in combination as described below. It is thought to be due to the synergistic effect of doing.
That is, the organic polybasic acid used for improving the polishing rate makes it easy for the abrasive grains and polishing residue to remain on the substrate, and the organic nitrogen compound adsorbs to the polishing particles and polishing residue to the polishing substrate. Presumed to prevent adhesion and residue of

  The organic nitrogen compound used in the present invention refers to a compound having two or more amino groups and / or imino groups in the molecule. The number of amino groups and imino groups in the molecule is not particularly limited, but is preferably 2 to 2000, more preferably 2 to 1000, and still more preferably 2 to 50, from the viewpoint of polishing rate and prevention of substrate contamination. Specific examples include polyalkyleneimines, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, bis (3-aminopropyl) amine, 1,3-propanediamine and the like.

  The polyalkyleneimines typically include polyethyleneimine, polypropyleneimine, polybutadieneimine, and the like, and examples include linear, branched, and cyclostructured ones. Among these, polyethyleneimine is preferable from the viewpoint of polishing rate and prevention of contamination. The molecular weight is preferably from 150 to 100,000, more preferably from 200 to 30,000, still more preferably from 200 to 10,000, and particularly preferably from 300 to 2,000 from the viewpoint of polishing rate and reduction of surface contamination.

  In addition, the content of the organic nitrogen compound in the polishing composition is preferably 0.001 to 0.5% by weight, and 0.001 to 0.3% by weight from the viewpoint of polishing rate and prevention of contamination of the substrate. More preferred is 0.001 to 0.1% by weight.

  As the organic polybasic acid used in the present invention, a sulfur-containing organic acid, a carboxylic acid, and a phosphorus-containing organic acid are preferable. Specific examples thereof include organic phosphonic acids such as methanedisulfonic acid, ethanedisulfonic acid, phenoldisulfonic acid, naphthalenedisulfonic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, malic acid. Polycarboxylic acids such as tartaric acid, citric acid, isocitric acid, phthalic acid, nitrotriacetic acid, ethylenediaminetetraacetic acid, phosphorus-containing compounds such as hydroxyethylidene-1,1-diphosphonic acid, phosphonobutanetricarboxylic acid, ethylenediaminetetramethylenephosphonic acid An organic acid etc. are mentioned. Of these, succinic acid, citric acid, malic acid, tartaric acid, hydroxyethylidene-1,1-diphosphonic acid, and ethylenediaminetetramethylenephosphonic acid are preferred from the viewpoint of improving the polishing rate, reducing waviness, and reducing roll-off. Acid and tartaric acid are more preferable, and citric acid is particularly preferable. These compounds may be used alone or in combination.

  The content of the organic polybasic acid is preferably 0.002% by weight or more, more preferably 0.005% by weight or more, more preferably 0.007% by weight or more, and more preferably 0.007% by weight or more in the polishing composition from the viewpoint of improving the polishing rate and reducing waviness. Preferably it is 0.01 weight% or more. From the viewpoint of surface quality and economy, it is preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 10% by weight or less, and further preferably 5% by weight or less. That is, the content of the organic polybasic acid in the polishing composition is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, still more preferably 0.007 to 10% by weight, and still more preferably 0.01 to 5% by weight. It is.

  In the polishing composition of the present invention, the weight ratio of the content of the organic nitrogen compound and the organic polybasic acid (organic nitrogen compound / organic polybasic acid) is determined from the viewpoint of polishing rate and prevention of substrate contamination. 1/10000 to 1/1 is preferable, 1/1000 to 1/2 is more preferable, and 1/500 to 1/5 is still more preferable.

  As the abrasive used in the present invention, an abrasive generally used for polishing can be used. Examples of the abrasive include metals; metal or metalloid carbides, nitrides, oxides, borides; diamond and the like. The metal or metalloid element is derived from Group 2A, 2B, 3A, 3B, 4A, 4B, 5A, 6A, 7A or Group 8 of the periodic table (long period type). Specific examples of abrasives include aluminum oxide particles such as α-alumina particles and intermediate alumina particles, silicon carbide particles, diamond particles, magnesium oxide particles, zinc oxide particles, cerium oxide particles, titanium oxide particles, zirconium oxide particles, colloidal silica. Examples thereof include particles and fumed silica particles. Among these, α-alumina particles, intermediate alumina particles, cerium oxide particles, zirconium oxide particles, colloidal silica particles, fumed silica particles, and the like are more preferable, and α-alumina particles, intermediate alumina particles, colloidal silica particles, fumed silica particles are more preferable. Particularly preferred are α-alumina particles and intermediate alumina particles. Furthermore, by using α-alumina and intermediate alumina in combination, a further polishing rate and waviness reduction effect can be obtained.

Among the α-alumina and the intermediate alumina, from the viewpoint of reducing waviness, reducing the surface roughness, improving the polishing rate and preventing surface defects, alumina having a purity of 95% or more is preferable, more preferably 97% or more, 99% or more of alumina is preferred. Further, α-alumina is preferable from the viewpoint of polishing rate, and intermediate alumina such as γ-alumina, δ-alumina, θ-alumina, η-alumina, and κ-alumina is preferable from the viewpoint of surface properties and waviness reduction. . The intermediate alumina used in the present invention is a general term for alumina particles other than α-alumina particles. Specifically, γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, these And the like. Among the intermediate aluminas, γ-alumina, δ-alumina, θ-alumina and a mixture thereof are preferable from the viewpoint of improving the polishing rate and reducing waviness, and γ-alumina and θ-alumina are particularly preferable.
In particular, in the case of intermediate alumina, the specific surface area measured by the BET method is preferably 30 to 300 m ² / g, more preferably 50 to ²⁰⁰ m ² / g.

  The average particle size of the primary particles of the abrasive is preferably 0.001 to 2 μm, more preferably 0.005 to 0.8 μm, and still more preferably 0.01 to 0.5 μm, from the viewpoint of improving the polishing rate and reducing waviness. Furthermore, when primary particles are aggregated to form secondary particles, the average particle size of the secondary particles is preferably 0.02 to 3 μm, from the viewpoint of improving polishing rate and reducing waviness and not generating surface defects. More preferably, it is 0.05-1 micrometer, More preferably, it is 0.1-0.8 micrometer. The average particle size of the primary particles of the abrasive is observed with a scanning electron microscope (preferably 3000 to 30000 times) or observed with a transmission electron microscope (preferably 10,000 to 500000 times), and image analysis is performed. It can be determined by measuring the diameter. The average particle size of the secondary particles can be measured as a volume average particle size using a laser beam diffraction method.

  The specific gravity of the abrasive is preferably 1.5 to 8, and more preferably 1.5 to 5, from the viewpoints of dispersibility, supply to a polishing apparatus and recovery and reusability.

  The content of the abrasive is preferably 0.05 to 40% by weight, more preferably 0.1 to 30% by weight, and still more preferably 0.5% in the polishing composition from the viewpoints of economy and improvement in polishing rate. -25% by weight, more preferably 1-20% by weight.

  The water in the polishing composition of the present invention is used as a medium, and the content thereof is preferably 55 to 99% by weight, more preferably 60 to 97, from the viewpoint of efficiently polishing an object to be polished. % By weight, more preferably 70 to 95% by weight.

  Moreover, other components can be mix | blended with the polishing liquid composition of this invention as needed.

  It is preferable to use an inorganic acid in combination with the polishing composition of the present invention from the viewpoint of further improving the polishing rate and reducing waviness. From the viewpoint of improving the polishing rate, nitric acid, nitrous acid, sulfuric acid, sulfurous acid and amidosulfuric acid are preferred, sulfuric acid, sulfurous acid and amidosulfuric acid are more preferred, and sulfuric acid is more preferred. The content of the inorganic acid in the polishing composition is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, and still more preferably 0.007 to 10% by weight from the viewpoints of polishing rate, surface quality and economy. More preferably, it is 0.01 to 5% by weight.

Moreover, it is preferable that the polishing liquid composition of this invention contains an oxidizing agent from a viewpoint of the improvement of polishing rate. The oxidizing agent is roughly classified into an inorganic oxidizing agent and an organic oxidizing agent. Inorganic oxidants include hydrogen peroxide, alkali metal or alkaline earth metal peroxides, peroxosulfuric acid or salts thereof, peroxonitric acid or salts thereof, peroxophosphoric acid or salts thereof, peroxoborate salts, peroxochrome. Acid salts, permanganates, halogen acids or derivatives thereof, inorganic acid metal salts, and the like can be used. As the organic oxidizing agent, percarboxylic acids, peroxides, iron (III) citrate and the like can be used. Among these, when comparing handling properties such as polishing rate improvement, availability, and water solubility, an inorganic oxidizer is preferable, and an inorganic peroxide containing no heavy metal is preferable in consideration of environmental issues. . Further, from the viewpoint of preventing surface contamination of the substrate to be polished, hydrogen peroxide, peroxosulfates, halogen acids or derivatives thereof are more preferable, and hydrogen peroxide is more preferable. These oxidizing agents may be used alone or in combination of two or more.

  The content of the oxidizing agent is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, and more preferably 0.005 to 15% by weight in the polishing composition from the viewpoints of improvement in polishing rate, reduction of waviness, surface quality, and economy. Preferably it is 0.007-10 weight%, Most preferably, it is 0.01-5 weight%.

  Examples of other components include celluloses such as cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose; water-soluble alcohols such as ethanol, propanol, and ethylene glycol; and surfactants such as alkyl benzene sulfonic acid. Examples thereof include salts, formalin condensates of naphthalenesulfonic acid, polyacrylates, lignin sulfonates, and the like, and water-soluble polymers such as polyvinyl alcohol. These components may be used alone or in combination of two or more. In addition, the content is preferably 0.001 to 20% by weight, more preferably 0.01 to 5% by weight, and still more preferably, in the polishing liquid composition, from the viewpoint of developing each function and from the viewpoint of economy. 0.01 to 2% by weight.

  In addition, although the density | concentration of each said component of polishing liquid composition is a density | concentration preferable at the time of grinding | polishing, the density | concentration at the time of this composition manufacture may be higher than these density | concentrations. Usually, the composition is produced as a concentrated liquid, and it is often used after being diluted at the time of use.

  The polishing composition of the present invention is suitably used for polishing a hard disk substrate as a substrate to be polished. The hard disk substrate is not particularly limited as long as it is a generally known substrate. For example, a Ni-P plated aluminum alloy substrate, a Ni-P plated glass substrate, and a metal layer on the surface layer of an aluminum disk or the like. Examples thereof include a substrate, a substrate having a glassy substance such as a carbon disk and a glass substrate, or a ceramic material, and a substrate in which they are combined. Among them, when the polishing composition of the present invention is used for a substrate having a metal layer on a surface layer such as a Ni-P plated aluminum alloy substrate, a Ni-P plated glass substrate, an aluminum disk, etc., abrasive grains and This is preferable because the polishing residue can be particularly reduced.

The pH of the polishing composition is preferably appropriately determined according to the type of substrate to be polished. For example, 1 to 12 is preferable from the viewpoint of the rinse property of the substrate, the corrosion prevention property of the processing machine, and the safety of the operator. In addition, when the substrate to be rinsed is mainly an aluminum alloy substrate plated with Ni-P, a glass substrate plated with Ni-P, or a substrate having a metal layer on a surface layer such as an aluminum disk, from the viewpoint of improving the polishing rate. The pH is preferably 1-7, more preferably 1-5, still more preferably 1-4, still more preferably 2-4, still more preferably 2 or more and less than 3. The pH can be adjusted by appropriately blending an inorganic acid, an organic acid, and a salt thereof, or a basic substance such as ammonia, sodium hydroxide, potassium hydroxide, or an amine as necessary.

  In the present invention, the residual prevention effect of abrasive grains and polishing residue of the polishing liquid composition can be evaluated by, for example, microscopic observation of a substrate surface obtained after polishing, observation by a scanning electron microscope, etc. Can be evaluated by observing the inner edge portion which is difficult to clean with these instruments. Further, the polishing substrate surface can be evaluated by glow discharge spectroscopic analysis (GDOES) or the like.

  The polishing liquid composition of the present invention having such a configuration can be used in a polishing process in a method for manufacturing a substrate such as a hard disk substrate, thereby preventing abrasive grains and polishing residue generated on the substrate from remaining on the substrate. As a result, it is possible to manufacture a substrate having no surface defects (scratches, pits) on the substrate surface and no abrasive grains or polishing residue. Accordingly, the present invention relates to a method for manufacturing a substrate.

  The manufacturing method of the board | substrate of this invention has the process of grind | polishing a to-be-polished board | substrate using the said polishing liquid composition. In this step, for example, the substrate is sandwiched with a polishing surface plate to which a porous organic polymer polishing cloth (polishing pad) or the like is attached, the polishing composition of the present invention is supplied to the polishing surface, and the pressure is applied. The substrate to be polished can be polished by moving the polishing platen and the substrate while adding. Therefore, this invention relates also to the method of grind | polishing a board | substrate using the said polishing liquid composition.

In the substrate manufacturing method of the present invention, from the viewpoint of improving the polishing rate and economically, it is preferably 0.01 to 0.5 mL / min, more preferably 0.02 to 0.3 mL / min per 1 cm ^{2 of the} substrate to be polished. It is preferable to have a step of supplying the polishing composition to the substrate and polishing with a polishing pad at a rate of 0.03 to 0.2 mL / min.

  In the method for producing a substrate of the present invention, the polishing pressure when polishing the polishing composition supplied between the substrate and the polishing pad is preferably 2 to 30 kPa, preferably from the viewpoint of improving the polishing rate and reducing waviness. Is preferably adjusted to 2 to 20 kPa, more preferably 4 to 15 kPa.

  There are no particular limitations on other conditions (type of polishing machine, type of polishing pad, polishing temperature, polishing rate, etc.) when polishing.

  The polishing composition of the present invention is particularly effective in the polishing process, but can be similarly applied to other polishing processes such as a lapping process.

Examples 1-13, Comparative Examples 1-5
Α-alumina shown in Table 1 (average primary particle size 0.07 μm, secondary particle average particle size 0.3 μm, specific surface area 15 m ² / g, purity 99.9%), θ-alumina (secondary particle average particle size) 0.2 μm, specific surface area 120 m ² / g, purity 99.9%), a predetermined amount of organic polybasic acid, organic nitrogen compound and other additives, and the remainder is stirred and mixed with ion-exchanged water to obtain a polishing composition. It was.

1. Polishing method The surface of a substrate made of Ni-P plated aluminum alloy with a thickness of 1.27mm and a diameter of 3.5 inches ("ZygoNewView5032", short wavelength undulation 3.8nm, long wavelength undulation 1.6nm) is processed by the double-sided processing machine as follows. Polishing was performed using the above polishing composition under the setting conditions of the processing machine to obtain a polished product of a Ni—P plated aluminum alloy substrate used as a substrate for a magnetic recording medium.
The setting conditions for the double-sided machine are shown below.

<Setting conditions of double-sided machine>
Double-sided processing machine: 9B type double-sided processing machine made by Speed Farm Co., Ltd. Processing pressure: 9.8kPa
Polishing pad: Fujibow Hard disk substrate polishing pad Surface plate rotation speed: 50r / min
Polishing liquid composition supply flow rate: 100 mL / min (0.076 mL / min per 1 cm ^{2 of} substrate to be polished)
Polishing time: 4min
Number of substrates loaded: 10

2. Evaluation method (1) Polishing speed Each substrate before and after polishing is weighed (measured using “BP-210S” manufactured by Sartorius) to determine the weight change of each substrate, and the average value of 10 substrates is taken as the reduction amount. The value obtained by dividing the result by the polishing time was defined as the weight reduction rate. The weight reduction rate was introduced into the following equation and converted to a polishing rate (μm / min).
Weight reduction rate (g / min) = {weight before polishing (g) −weight after polishing (g)} / polishing time (min)
Polishing rate (μm / min) = Weight reduction rate (g / min) / Substrate single side area (mm ² )
/ Ni-P plating density (g / cm ³ ) × 1000000
Table 1 shows the relative values (relative speeds) of the polishing rates of the examples and comparative examples, with the polishing rate of comparative example 1 being the reference value 1.

(2) Surface contamination The surface of each substrate after polishing was observed with a scanning electron microscope (manufactured by Hitachi, Ltd .: S-4000) at a magnification of 10,000, and the following five-level evaluation was performed. 1 and 2 are practical defects.
5: Alumina residue, polishing debris, etc. are not observed at all on the surface. 4: A very small amount is observed. 3: A small amount is observed. 2: A large amount is observed. 1: A very large amount is observed.

(3) Waviness Regarding the waviness of each substrate after polishing, two types of waviness of short wavelength and long wavelength were measured according to the following conditions. Table 1 shows the relative values of the swells of the examples and comparative examples, with the swell of Comparative Example 1 as the reference value 1. A lower value indicates less waviness.
Equipment: Zygo NewView5032
Lens: 2.5x Micheison
Zoom ratio: 0.5
Remove: Cylinder
Filter: FFT Fixed Band Pass
Short wavelength swell: 50-500μm
Long wavelength swell: 0.5 to 5mm
Area: 4.33mm x 5.77mm

  From the results shown in Table 1, the polishing liquid compositions obtained in Examples 1 to 13 have significantly less surface contamination of the substrate after polishing than those of Comparative Examples 1 to 5, and the substrate is wavy. It turns out that it is difficult.

  The polishing composition of the present invention can be suitably used, for example, in the production process of a substrate for a hard disk such as a memory hard disk.

Claims (11)

  A polishing composition comprising an organic nitrogen compound having two or more amino groups and / or imino groups in the molecule, an organic polybasic acid, an abrasive, and water is supplied to the substrate, and the substrate is prepared using a polishing pad. A method for producing a hard disk substrate, comprising a polishing step. The production according to claim 1, wherein the organic nitrogen compound is selected from the group consisting of polyalkyleneimines, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, bis (3-aminopropyl) amine, and 1,3-propanediamine. Method. The manufacturing method of Claim 2 whose molecular weight of the said polyalkyleneimines is 150-2000.   The production according to any one of claims 1 to 3, wherein the organic polybasic acid is selected from the group consisting of succinic acid, citric acid, malic acid, tartaric acid, hydroxyethylidene-1,1-diphosphonic acid, and ethylenediaminetetramethylenephosphonic acid. Method.   The manufacturing method in any one of Claims 1-4 whose content of the said organic nitrogen compound is 0.001-0.5 weight%.   The manufacturing method in any one of Claims 1-5 whose content of the said polybasic acid is 0.002 to 20 weight%.   The manufacturing method in any one of Claims 1-6 whose weight ratio (organic nitrogen compound / organic polybasic acid) of content of the said organic nitrogen compound and the said organic polybasic acid is 1/10000-1/1.   The manufacturing method in any one of Claims 1-7 whose content of the said abrasives is 0.05 to 40 weight%.   The manufacturing method in any one of Claims 1-8 whose pH is 1-7.   The manufacturing method in any one of Claims 1-9 whose polishing pressure is 2-30 kPa. The manufacturing method according to claim 1, wherein the polishing liquid composition is supplied to the substrate at a rate of 0.01 to 0.5 mL / min per 1 cm ^{2 of the} substrate to be polished.