CN1320078C - Polishing composition - Google Patents

Abstract

The present invention relates to a polishing liquid composition containing α-alumina, intermediate alumina, an oxidizing agent and water, a method for reducing surface ripples of a ground substrate in the process of using the polishing liquid composition to polish a ground substrate, and having the method of using the above-mentioned The manufacturing method of the substrate in the process of polishing the substrate to be polished with the polishing liquid composition. The above-mentioned polishing liquid composition is suitable for grinding substrates of magnetic recording media such as magnetic disks, optical disks, and magneto-optical disks, photomask substrates, optical lenses, optical mirrors, optical prisms, and substrates for precision components such as semiconductor substrates.

Description

Slurry Composition

technical field

The present invention relates to a polishing liquid composition with high polishing speed and capable of reducing surface waviness of a substrate to be polished. Further, the present invention relates to a method for reducing surface waviness of a substrate to be polished using the polishing liquid composition and a method for manufacturing the substrate.

Background technique

In order to reduce the minimum recording area and increase the capacity of hard disks, it is required to reduce the floating amount of the magnetic head. In order to reduce the floating amount of the magnetic head, it is necessary to reduce short-wavelength surface waviness (surface waviness with a wavelength of 50 to 500 μm) and long-wavelength surface waviness (surface waviness with a wavelength of 0.5 mm or more) in the polishing process of the hard disk substrate. The term "surface waviness" as used herein refers to surface irregularities longer than the wavelength of the surface roughness. In order to manufacture such a substrate with reduced surface waviness, mechanical conditions such as control of the pore diameter of the polishing pad, control of the hardness, and control of the polishing load and rotational speed during polishing were studied. However, although these mechanical conditions are effective, they cannot be said to be sufficient. On the other hand, the reduction of surface waviness by slurry composition has also been studied. JP-P3-115383 communiqué has studied the abrasive liquid composition that contains α-alumina, water-soluble peroxide and boehmite; The grinding liquid composition of colloidal particles and oxidizing agent; Japanese Patent Application Publication No. 2002-327170 (US 2002194789 A1) discloses a polishing liquid composition containing colloidal silicon dioxide, oxidizing agent and organic phosphonic acid; Japanese Patent Application Publication No. 2003-41239 ( US 2003041526 A1) discloses a polishing liquid composition using intermediate alumina. However, these polishing liquid compositions cannot be said to be sufficient from the viewpoint of reducing surface waviness at a polishing rate required for practical use.

Contents of the invention

That is, the gist of the present invention involves

(1) A polishing liquid composition containing α-alumina, intermediate alumina, an oxidizing agent and water;

(2) reduce the surface corrugation method of polished substrate with the polishing liquid composition described in above-mentioned (1); And

(3) A method for producing a substrate comprising a step of polishing a substrate to be polished with the polishing liquid composition described in the above (1).

Detailed ways

The present invention relates to the polishing fluid composition that has high grinding speed, can reduce the surface corrugation of polished substrate, also relate to the method for using this polishing fluid composition to reduce the surface corrugation of polished substrate, and use this polishing fluid composition to make the surface A method of manufacturing a high-quality substrate with reduced waviness.

These and other advantages of the present invention will become apparent from the following description.

The polishing liquid composition of the present invention, its major feature is abrasive material and uses α-alumina and middle aluminum oxide, and grinding accelerator uses oxidizing agent, finds that by using the polishing liquid composition with this feature, high grinding can be achieved Speed, and can significantly reduce the surface waviness of the polished substrate.

By using α-alumina and intermediate alumina in combination, the effect of increasing the grinding speed and reducing surface waviness is obtained. Regarding the mechanism of this action, it is speculated that the filling properties are improved due to the different particle sizes and hardness, and the grinding physical force Effectively acts on the surface of the object to be ground, but it is not limited to this.

The polishing liquid composition of the present invention contains α-alumina as a polishing material. As α-alumina, gibbsite, bayerite, nordstrandite, diaspore, boehmite, pseudoboehmite, aluminum gel, γ-alumina and θ-alumina and the like are aluminas fired at a temperature above 1100°C by conventional methods. From the viewpoint of reducing surface waviness, reducing surface roughness, increasing grinding speed, and preventing surface defects, α-alumina is preferably alumina with a purity of 95% or more, more preferably 97% or more, and still more preferably 99% above.

The average particle size of the primary particles of α-alumina is preferably 0.005 to 0.8 μm, more preferably 0.01 to 0.4 μm from the viewpoint of reducing surface waviness, and the average particle size of the secondary particles is preferably 0.01 to 2 μm, more preferably It is 0.05 to 1.0 μm, more preferably 0.1 to 0.5 μm. The average particle size of the primary particles of the grinding material is observed with a scanning electron microscope (preferably 3000 to 30000 times) or a transmission electron microscope (preferably 10000 to 300000 times), and image analysis is carried out. The average value of the long diameter and the short diameter can be used as Calculate the number average particle size. The average particle diameter of the secondary particles can be measured as a volume average particle diameter by a laser diffraction method.

From the viewpoint of increasing the grinding speed and reducing surface waviness, the specific surface area of α-alumina measured by BET method is preferably 0.1-50m ² /g, more preferably 1-40m ² /g, and still more preferably 2-20m ² /g.

From the viewpoint of improving the grinding speed and reducing surface ripples, the content of α-alumina in the polishing liquid composition is preferably more than 0.05% by weight, more preferably more than 0.1% by weight, more preferably more than 0.5% by weight, and more preferably 1% by weight or more. From the viewpoint of surface quality and economic efficiency, it is preferably 40% by weight or less, more preferably 30% by weight or less, still more preferably 25% by weight or less, and still more preferably 20% by weight or less. That is, the content of α-alumina in the polishing liquid composition is preferably 0.05 to 40% by weight, more preferably 0.1 to 30% by weight, still more preferably 0.5 to 25% by weight, and still more preferably 1 to 20% by weight.

From the standpoint of increasing the polishing speed and reducing surface waviness, the polishing liquid composition of the present invention should contain intermediate alumina. The intermediate alumina in the present invention is a general term for alumina particles other than α-alumina particles, and specific examples include γ-alumina particles, δ-alumina particles, θ-alumina particles, η-alumina particles, κ-alumina particles, Aluminum particles and their mixtures, etc. Among these, the following intermediate aluminas are preferred from the viewpoint of increasing the polishing rate and reducing surface waviness. Its crystal form is preferably γ-alumina, δ-alumina, θ-alumina and their mixtures, more preferably γ-alumina and θ-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. From the viewpoint of reducing surface waviness, the average particle diameter of secondary alumina particles is preferably 0.01-5 μm, more preferably 0.01-2 μm, still more preferably 0.05-1 μm, still more preferably 0.1-0.5 μm. This average particle diameter can be measured as a volume average particle diameter by the laser diffraction method called "LA-920" manufactured by Horiba, Ltd., for example.

The content of alkali metals and alkaline earth metals in intermediate alumina is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and still more preferably 0.01% by weight or less. For example, when aluminum hydroxide with a relatively large specific surface area and low content of alkali metals and alkaline earth metals is used as a raw material, the produced intermediate alumina has less welding and particle strength is also small, so the surface of the object to be ground can be effectively reduced. defect.

Aluminum hydroxide as a raw material for intermediate alumina has a specific surface area measured by the BET method of preferably 10 to 500 m ² /g, more preferably 30 to 400 m ² /g, still more preferably 50 to 300 m ² /g. The content of alkali metals and alkaline earth metals in aluminum hydroxide is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and still more preferably 0.01% by weight or less. When aluminum hydroxide is heated and dehydrated to produce intermediate alumina, dry air or nitrogen is introduced during heating, which can effectively prevent surface defects of the ground object. The above-mentioned heat dehydration treatment can be performed according to a conventional method. These intermediate aluminas can be wet or dry pulverized by pulverizers such as ball mills, bead mills, high-pressure homogenizers, and jet mills to adjust to a predetermined particle size as needed.

Aluminum hydroxide is a compound represented by the chemical formula Al(OH) ₃ , AlOOH, AlOOH·nH ₂ O or Al ₂ O ₃ ·nH ₂ O (n is 1 to 3), as long as it is a compound capable of heating and dehydrating to produce intermediate alumina. Yes, there is no particular limitation. Specific examples include gibbsite, bayerite, neoalumina, diaspore, boehmite, pseudoboehmite, aluminum gel, and the like.

The details of the mechanism of action of this intermediate alumina during grinding are unclear, but it is considered that the grinding speed increases when the two are mixed compared with the use of α-alumina alone and the intermediate alumina alone, so the physical force on the surface of the object to be polished Increase.

From the viewpoint of improving the grinding speed and reducing surface ripples, the content of intermediate alumina in the polishing liquid composition is preferably more than 0.05% by weight, more preferably more than 0.1% by weight, more preferably more than 0.5% by weight, and more preferably 1% by weight. % by weight or more. From the viewpoint of surface quality and economic efficiency, it is preferably 40% by weight or less, more preferably 30% by weight or less, still more preferably 25% by weight or less, and still more preferably 20% by weight or less. That is, the content of intermediate alumina in the polishing liquid composition is preferably 0.05 to 40% by weight, more preferably 0.1 to 30% by weight, still more preferably 0.5 to 25% by weight, and still more preferably 1 to 20% by weight.

From the viewpoint of increasing the grinding speed and reducing surface ripples, the weight ratio of α-alumina to intermediate alumina (α-alumina/intermediate alumina) is preferably 99/1 to 30/70, more preferably 97/3 to 40/60, more preferably 95/5-50/50, more preferably 93/7-55/45.

In order to effectively increase the grinding speed and reduce surface waviness, the total amount of α-alumina and intermediate alumina is preferably 0.1 to 45% by weight, more preferably 0.2 to 35% by weight, more preferably 1 to 30% by weight, and more preferably 2 to 25% by weight.

From the viewpoint of increasing the polishing speed and reducing surface waviness, the polishing liquid composition of the present invention should contain an oxidizing agent. The mechanism of grinding is not clear, but it is presumed that the grinding effect of alumina can be fully exerted by the action of the oxidizing agent on the material to be ground. The oxidizing agent used in the present invention includes, for example, peroxides, metal peroxyacids or salts thereof, oxyacids or salts thereof, nitrates, sulfates, metal salts of acids, and the like. Oxidants can be roughly divided into inorganic oxidants and organic oxidants according to their structures. Specific examples of these oxidizing agents are shown below. As the inorganic oxidizing agent, hydrogen peroxide, alkali metals such as sodium peroxide, potassium peroxide, calcium peroxide, barium peroxide, and magnesium peroxide, or peroxides of alkaline earth metals, sodium percarbonate, percarbonic acid, etc., can be used. Percarbonates such as potassium, ammonium peroxodisulfate, sodium peroxodisulfate, potassium peroxodisulfate, persulfuric acid such as permonosulfuric acid or its salts, pernitric acid such as pernitric acid, sodium pernitrate, potassium pernitrate or its salts , sodium superphosphate, potassium superphosphate, ammonium superphosphate and other superphosphoric acid or its salts, sodium perborate, potassium perborate and other perborates, potassium perchromate, sodium perchromate and other perchromates, high Potassium manganate, sodium permanganate and other permanganates, sodium perchlorate, potassium perchlorate, chloric acid, sodium hypochlorite, sodium periodate, potassium periodate, iodic acid, sodium iodate and other halogen acids or their derivatives Species, iron (III) chloride, iron (III) sulfate and other inorganic acid metal salts. As the organic oxidizing agent, percarboxylic acids such as peracetic acid, performic acid, and perbenzoic acid, peroxides such as tert-butyl peroxide and cumene peroxide, and iron (III) citrate can be used. Among them, the inorganic oxidizing agent is preferably used when comparing the polishing rate improvement, ease of availability, and water solubility. From the viewpoint of environmental problems, inorganic peroxides that do not contain heavy metals are preferred. From the viewpoint of preventing contamination of the surface of the substrate to be polished, hydrogen peroxide, persulfates, halogen acids or derivatives thereof are more preferred, and hydrogen peroxide is still more preferred. These peroxides may be used alone or in combination of two or more.

From the viewpoint of increasing the grinding speed and reducing surface ripples, the content of the oxidant in the polishing liquid composition is preferably more than 0.002% by weight, more preferably more than 0.005% by weight, more preferably more than 0.007% by weight, and more preferably more than 0.01% by weight . From the viewpoint of surface quality and economic efficiency, it is preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 10% by weight or less, and still more preferably 5% by weight or less. That is, the content of the oxidizing agent in the polishing liquid composition is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, even more preferably 0.007 to 10% by weight, and still more preferably 0.01 to 5% by weight.

From the viewpoint of increasing the polishing rate and reducing surface waviness, it is preferable that the polishing liquid composition of the present invention further contains an acid.

From the viewpoint of improving the grinding speed and reducing surface waviness, the pK1 of the acid used in the present invention is preferably 7 or less, more preferably 5 or less, more preferably 3 or less, and still more preferably 2 or less. Here, when the log value of the reciprocal of the acid dissociation constant (25° C.) is expressed as pKa, pK1 is the log value of the reciprocal of the first acid dissociation constant among them. The pK1 of each compound is described, for example, in Chemical Handbook Revised 4th Edition (Basic Edition) II, pp 316-325 (edited by the Chemical Society of Japan), and the like.

Specific examples of acids used in the present invention are shown below. Examples of inorganic compounds include monobasic inorganic acids such as nitric acid, hydrochloric acid, perchloric acid, and amide sulfuric acid, and polybasic inorganic acids such as sulfuric acid, sulfurous acid, phosphoric acid, pyrophosphoric acid, polyphosphoric acid, phosphonic acid, and phosphinic acid. . Examples of organic compounds include monocarboxylic acids such as formic acid, acetic acid, glycolic acid, lactic acid, propionic acid, hydroxypropionic acid, butyric acid, benzoic acid, and glycine, oxalic acid, succinic acid, glutaric acid, adipic acid, and maleic acid. , fumaric acid, itaconic acid, malic acid, tartaric acid, citric acid, isocitric acid, phthalic acid, nitrotriacetic acid, ethylenediaminetetraacetic acid and other polycarboxylic acids, methanesulfonic acid, p-toluenesulfonic acid, etc. Alkyl sulfonic acids, ethyl phosphoric acid, butyl phosphoric acid and other alkyl phosphoric acids, phosphonoglycolic acid, hydroxyethylene diphosphonic acid, phosphonobutane tricarboxylic acid, ethylenediaminetetramethylenephosphonic acid, etc. Organic phosphonic acids. Among them, from the viewpoint of increasing the grinding rate and reducing surface waviness, polybasic acids are preferred, polybasic inorganic acids, polybasic organic carboxylic acids, and polybasic organic phosphonic acids are more preferred, and polybasic inorganic acids and polybasic organic carboxylic acids are more preferred. Here, the polybasic acid refers to an acid having two or more hydrogen atoms capable of generating hydrogen ions in a molecule. From the viewpoint of preventing contamination of the surface of the substrate to be polished, nitric acid, sulfuric acid, phosphonic acid, and carboxylic acid are preferable.

The above acids may be used alone, but are preferably used in combination of two or more. Wherein, when grinding a metal surface such as a nickel-phosphorus (Ni-P) substrate, when the metal ions of the grinding object are dissolved out during the grinding process, the pH of the polishing liquid composition rises, and when a high grinding speed cannot be obtained, in order to reduce The pH change is preferably a combination of an acid with a pK1 of less than 2.5 and an acid with a pK1 of 2.5 or more, more preferably a combination of an acid with a pK1 of 1.5 or less and an acid with a pK1 of 2.5 or more. When containing such two or more acids, from the viewpoint of increasing the grinding speed and reducing surface ripples, and the ease of availability of the acid, in acids with pK1 less than 2.5, inorganic acids such as nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid and organic acids are preferably used. Phosphonic acid. On the other hand, among acids having a pK1 of 2.5 or more, organic carboxylic acids such as acetic acid, succinic acid, malic acid, tartaric acid, and citric acid are preferable from the same viewpoint.

From the viewpoint of improving the grinding speed and reducing surface ripples, the total content of the above-mentioned acids in the polishing liquid composition is preferably more than 0.002% by weight, more preferably more than 0.005% by weight, more preferably more than 0.007% by weight, and more preferably 0.01% by weight %above. From the viewpoint of surface quality and economical efficiency, the total content is preferably 20% by weight or less, more preferably 15% by weight or less, more preferably 10% by weight or less, and still more preferably 5% by weight or less. That is, the total content of acids in the polishing composition is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, even more preferably 0.007 to 10% by weight, and still more preferably 0.01 to 5% by weight. From the viewpoint of increasing the grinding speed, the weight ratio of the acid with pK1 less than 2.5 to the acid with pK1 of 2.5 or more (acid with pK1 less than 2.5/acid with pK1 of 2.5 or more) is preferably 9/1 to 1/9, more preferably 7/1 to 1/7, more preferably 5/1 to 1/5.

The water in the polishing liquid composition of the present invention is used as a medium, and from the viewpoint of effectively grinding the object to be ground, its content is preferably 50 to 99% by weight, more preferably 60 to 97% by weight, and even more preferably 70 to 99% by weight. 95% by weight.

From increasing the grinding speed, reducing surface waviness, and according to other purposes, the polishing liquid composition of the present invention can be further compounded with other components, such as inorganic salts, thickeners, rust inhibitors, alkaline substances, etc. Examples of inorganic salts include ammonium nitrate, ammonium sulfate, potassium sulfate, nickel sulfate, aluminum nitrate, aluminum sulfate, ammonium sulfamate, and the like. These other components may be used alone or in combination of two or more. From the viewpoint of economical efficiency, its content in the polishing liquid composition is preferably 0.05 to 20% by weight, more preferably 0.05 to 10% by weight, and still more preferably 0.05 to 5% by weight.

As other components, a bactericide, an antibacterial agent, etc. can be further compounded as needed. From the point of view of bringing into play its function, from the point of view of the impact on grinding performance and economic efficiency, the content of these bactericides and antibacterial agents in the polishing liquid composition is preferably 0.0001 to 0.1% by weight, more preferably 0.001 to 0.05% by weight, More preferably, it is 0.002 to 0.02% by weight.

The concentration of each component of the polishing liquid composition of the present invention is the preferred concentration at the time of polishing, but may be the concentration at the time of preparation of the composition. Usually, the composition is prepared in the form of a concentrate in most cases, which is diluted before or at the time of use.

In addition, the polishing liquid composition can be prepared by adding and mixing required components by any method.

The pH of the polishing liquid composition is preferably appropriately determined according to the type and required quality of the object to be polished. For example, from the viewpoint of improving the grinding speed and reducing surface waviness, from the viewpoint of the corrosion resistance of the processing machine and the safety of the operator, the pH of the polishing liquid composition is preferably less than 7, more preferably 0.1 to 6, and more preferably 0.5 ~5, more preferably 1~4, even more preferably 1~3. According to needs, the pH can be adjusted by properly blending the required amount of inorganic acids such as nitric acid and sulfuric acid, organic acids such as hydroxy acids, polycarboxylic acids, amino polycarboxylic acids, amino acids, or their metal salts, ammonium salts, ammonia water, and sodium hydroxide. , potassium hydroxide, amine and other alkaline substances to adjust.

The manufacturing method of the substrate of the present invention includes the step of polishing the substrate to be polished with the above-mentioned polishing liquid composition.

The material of the object to be polished represented by the substrate to be polished as the object of the present invention includes, for example, metals or metalloids such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, and alloys mainly composed of these metals, glass , glassy carbon, amorphous carbon and other glassy substances, alumina, silicon dioxide, silicon nitride, tantalum nitride, titanium carbide and other ceramic materials, polyimide resin and other resins, etc. Among them, metals such as aluminum, nickel, tungsten, and copper, and alloys mainly composed of these metals are preferable, or semiconductor substrates such as semiconductor elements containing these metals are preferable. In particular, when the polishing liquid composition of the present invention is used on a substrate made of a Ni-P-plated aluminum alloy, surface waviness can be significantly reduced, which is preferable. The shape of the object to be ground is not particularly limited. For example, shapes with flat parts such as discs, flakes, plates, and prisms, and shapes with curved parts such as lenses are all objects to be polished with the polishing liquid composition of the present invention. Among them, it is particularly excellent in polishing a disc-shaped to-be-polished object.

The present invention further relates to a method of reducing surface waviness of the above-mentioned ground substrate. In the method of reducing surface waviness of a substrate to be polished using the polishing liquid composition of the present invention, surface waviness can be significantly reduced by polishing the above-mentioned substrate to be polished using the polishing liquid composition of the present invention. For example, clamp the substrate with a grinding disc with a porous organic polymer system grinding cloth, etc., supply the polishing liquid composition of the present invention to the grinding surface, and rotate the grinding disc and the substrate while applying pressure, so that surface waviness can be reduced. High quality substrate.

The polishing liquid composition of the present invention is suitable for polishing substrates for precision parts. For example, it is suitable for grinding substrates of magnetic recording media such as magnetic disks, optical disks, and magneto-optical disks, photomask substrates, optical lenses, optical mirrors, optical prisms, and semiconductor substrates. The polishing of semiconductor substrates includes, for example, the polishing process of a silicon wafer (bare wafer), the formation process of an embedded element separation film, the planarization process of an interlayer insulating film, the formation process of an embedded metal wiring, the embedded Polishing performed in the capacitor forming process, etc. The polishing liquid composition of the present invention is particularly effective in the polishing process, but it can also be applied to other polishing processes, such as lapping processes. The polishing liquid composition of the present invention is particularly suitable for polishing a substrate for a magnetic disk.

Example

The mode of the present invention is further described and described in detail through the following examples, and these examples only disclose the present invention and do not represent any limitation.

Examples 1-17, Comparative Examples 1-5

[Grinding liquid preparation method]

Stir and mix the given amount of α-alumina shown in Tables 1 to 3 (the average particle diameter of the primary particles is 0.07 μm, the average particle diameter of the secondary particles is 0.3 μm, the specific surface area is 15 m ² /g, and the purity is 99.9% ), θ-alumina (the average particle size of the secondary particles is 0.2μm, the specific surface area is 120m ² /g, and the purity is 99.9%), oxidant, acid and other additives, and the balance is ion-exchanged water, adjusted with ammonia water pH, to obtain the polishing liquid composition.

[grinding method]

The centerline average roughness Ra measured with a Talystep manufactured by Rank Taylor Hobson (stylus tip size: 25 μm × 25 μm, bypass filter: 80 μm, measurement length: 0.64 mm) is 0.2 μm, thickness is 1.27 mm, diameter is The surface of a 3.5-inch (95.0mm) Ni-P-plated aluminum alloy is polished under the setting conditions of the following double-side processing machine with a double-side processing machine to obtain a Ni-P-plated aluminum used as a substrate for a magnetic recording medium. Abrasives for alloy substrates.

The setting conditions of the double-sided processing machine are as follows.

<Setting conditions of double-sided processing machine>

Double-sided processing machine: Made by Speedfam, 9B type double-sided processing machine

Processing pressure: 9.8kPa

Polishing pad: "H9900S" (trade name) manufactured by Fujibo Corporation

Fixed plate speed: 50r/min

Supply flow rate of polishing liquid composition: 100ml/min

Grinding time: 5 minutes

The number of substrates put in: 10

[grinding speed]

The weight of each substrate before and after polishing was measured with a balance ("BP-210S" manufactured by Sartorius Co., Ltd.), and the weight change of each substrate was obtained. The average value of 10 pieces was used as the amount of decrease, and the value obtained by dividing it by the polishing time was taken as the weight. Reduce speed. The weight reduction rate was introduced into the following formula to convert it into a polishing rate (μm/min). Using the polishing rate of Comparative Example 1 as a reference value 1, the relative value (relative speed) of the polishing rate of each Example or Comparative Example was obtained.

Weight reduction rate (g/min) = {weight before grinding (g) - weight after grinding (g)}

/ Grinding time (minutes)

Polishing speed (μm/min) = Weight reduction rate (g/min)/Substrate surface area (mm ² )

/Ni-P plating density (g/cm ³ )×10 ⁶

[surface ripple]

Two points (4 points in total) were taken at intervals of 180° from each polished substrate, and short-wavelength surface waviness and long-wavelength surface waviness were measured under the following conditions.

Machine: "Zygo New View200"

Objective lens: 2.5x "Michelson"

Zoom ratio: 0.5

Move out: Cylinder

Filter: FFT fixed band pass (Band Pass)

Measurement wavelength:

·Short wavelength surface ripple: filter high wavelength 50μm

Filter low wavelength 500μm

·Long wavelength surface ripple: filter high wavelength 0.5mm

Filter low wavelength 5mm

Area: 4.33mm×5.77mm

[surface dirty]

Each polished substrate was washed with detergent water and ion-exchanged water using PVA (polyvinyl acetate) slices in a leaf-type washer, and then observed with a polarizing microscope at 300 times, and the surface dirt was checked for 4 times. grade evaluation.

◎: No aluminum oxide residue and grinding dust are present on the surface.

◯: There are almost no alumina residues and abrasive dust on the surface.

△: Alumina residues and grinding dust are present in some places on the surface.

X: There are many alumina residues and grinding dust on the surface.

The results are shown in Tables 1 and 2. The values of the polishing rate and surface waviness are relative values based on the value of Comparative Example 1 as the reference value 1. It can be seen that, compared with the comparative examples, the polishing liquid compositions obtained in Examples 1-12 containing α-alumina, intermediate alumina, and oxidizing agents are excellent in both performance of improving the polishing speed and reducing surface waviness. In particular, when an acid is added, its effect is remarkable. Furthermore, the polishing liquid compositions obtained in Examples 1 to 12 also have the effect of preventing contamination of the substrate to be polished.

Table 1 α-alumina (%) θ-alumina (%) Oxidant (%) acid(%) pH grinding speed Surface ripple (relative value) Dirty substrate relative value short wavelength long wavelength Example 1 3 1 hydrogen peroxide 0.6 - - 4.1 2.5 0.59 0.77 ○ Example 2 3.5 0.5 hydrogen peroxide 0.6 citric acid 3.0 2.0 29 0.24 0.43 ◎ Example 3 2 2 hydrogen peroxide 0.6 citric acid 3.0 2.0 28 0.23 0.38 ◎ Example 4 1 3 hydrogen peroxide 0.6 citric acid 3.0 2.0 20 0.21 0.34 ◎ Example 5 3 1 hydrogen peroxide 0.6 citric acid 3.0 2.0 42 0.26 0.25 ◎ Example 6 3 1 hydrogen peroxide 0.6 nitric acid 1.1 0.8 36 0.27 0.42 ◎ Example 7 3 1 hydrogen peroxide 0.6 sulfuric acid 1.7 0.8 53 0.26 0.21 ◎ Example 8 3 1 hydrogen peroxide 1.8 sulfuric acid 5.1 0.5 63 0.25 0.19 ◎ Example 9 3 1 hydrogen peroxide 0.6 Methanesulfonic acid 1.7 0.8 41 0.26 0.30 ◎ Example 10 3 1 hydrogen peroxide 0.6 phosphoric acid 1.7 1.4 34 0.27 0.35 ○ Example 11 3 1 hydrogen peroxide 0.6 Hydroxyethylene diphosphonic acid 1.8 1.2 44 0.26 0.22 ○ Example 12 3 1 hydrogen peroxide 0.6 polyphosphoric acid 1.4 1.4 37 0.25 0.27 ○ Comparative example 1 3 1 - - - - 4.1 1 1 1 x

In the table, % means % by weight.

Table 2 α-alumina (%) θ-alumina (%) Oxidant (%) Acid and other additives (%) pH grinding speed Surface ripple (relative value) Dirty substrate relative value short wavelength long wavelength Comparative example 1 3 1 - - - - 4.1 1 1 1 x Comparative example 2 3 0 hydrogen peroxide 0.6 boehmite 1.0 4.1 1.1 0.91 0.92 ○ Comparative example 3 3 0 Aluminum nitrate 0.6 Colloidal silicon dioxide ^*) 1.0 4.1 2.0 0.59 0.77 △ Comparative example 4 3 1 citric acid 0.5 3.0 2.3 0.72 0.85 △ Comparative Example 5 0 0 hydrogen peroxide 0.6 Colloidal silica ^*) hydroxyethylene diphosphonic acid 4.01.8 1.2 1.5 0.27 0.92 ◎

In the table, % means % by weight.

^* ): average particle size 0.05μm, purity 99.9%.

Table 3 shows the results when the pH was higher than that in Table 1 in consideration of the safety to the human body and the corrosion resistance to machines. It can be seen that, compared with Comparative Example 1, the polishing liquid compositions obtained in Examples 13 to 17 are excellent in both the improvement of the polishing speed and the reduction of surface waviness. In addition, compared with the case of using a single acid (Examples 13 and 14), when two kinds of acids such as carboxylic acids and inorganic acid sulfuric acid were used in combination in Examples 15 to 17, the effect of increasing the polishing rate and reducing surface waviness was further improved. . Furthermore, the polishing liquid compositions obtained in Examples 13 to 17 all have the effect of preventing contamination of the substrate to be polished.

In addition, it can be seen that, since the surface waviness evaluated in Examples 1-17 is micro-surface waviness, the polishing liquid compositions obtained in Examples 1-17 all have the effect of significantly reducing micro-surface waviness.

table 3 α-alumina (%) θ-alumina (%) Oxidant (%) Acid ^*) (%) (%) pH grinding speed Surface ripple (relative value) Dirty substrate relative value short wavelength long wavelength Example 13 3 1 hydrogen peroxide 0.6 citric acid 1.0 - - 2.2 35 0.29 0.37 ◎ Example 14 3 1 hydrogen peroxide 0.6 - - sulfuric acid 1.1 2.1 20 0.29 0.40 ○ Example 15 3 1 hydrogen peroxide 0.6 citric acid 1.0 sulfuric acid 1.1 2.1 49 0.25 0.19 ◎ Example 16 3 1 hydrogen peroxide 0.6 tartaric acid 1.0 sulfuric acid 1.1 2.1 40 0.27 0.22 ◎ Example 17 3 1 hydrogen peroxide 0.6 Acetic acid 1.0 sulfuric acid 1.1 2.1 41 0.26 0.20 ◎ Comparative example 1 3 1 - - - - - - 4.1 1 1 1 x

In the table, % means % by weight.

^* ): citric acid pK1=2.9, tartaric acid pK1=2.8, acetic acid pK1=4.6, sulfuric acid pK1<0.

The polishing liquid composition of the present invention can be applicable to the substrate that grinds precision parts, for example is suitable for the substrate of the magnetic recording medium such as grinding disk, optical disk, magneto-optical disk, photomask substrate, optical lens, optical reflection mirror, optical prism, semiconductor substrate wait.

When the polishing liquid composition of the present invention is used for polishing substrates for precision components, etc., it can achieve a high polishing rate and reduce surface waviness of objects to be polished. Among them, the surface corrugations composed of short-wavelength surface corrugations with a wavelength of 50-500 μm and long-wavelength surface corrugations with a wavelength of 0.5-5 mm are called micro-surface corrugations. The present invention has the effect of significantly reducing such micro-surface corrugations.

In addition, since the obtained polished product has less contamination such as grinding dust, and can be easily cleaned after polishing, it is possible to economically manufacture a high-quality substrate with reduced surface waviness.

With the invention thus described, it will be apparent that there are many forms within the same scope. It is considered that such diversity does not depart from the spirit and scope of the invention, and it should be understood that all changes made by those skilled in the art fall within the scope of the claims.

Claims (18)

1, the grinding Liquid composition that contains Alpha-alumina, intermediate alumina, hydrogen peroxide, water and acid.

2, grinding Liquid composition according to claim 1, its pH is less than 7.

3, grinding Liquid composition according to claim 1, wherein the weight ratio of Alpha-alumina and intermediate alumina (Alpha-alumina/intermediate alumina) is 99/1～30/70.

4, grinding Liquid composition according to claim 2, wherein the weight ratio of Alpha-alumina and intermediate alumina (Alpha-alumina/intermediate alumina) is 99/1～30/70.

5, grinding Liquid composition according to claim 1, wherein the median size of the offspring of Alpha-alumina is 0.01～2 μ m, and specific surface area is 0.1～50m ²/ g, the median size of the offspring of intermediate alumina is 0.01～5 μ m, and specific surface area is 30～300m ²/ g.

6, grinding Liquid composition according to claim 2, wherein the median size of the offspring of Alpha-alumina is 0.01～2 μ m, and specific surface area is 0.1～50m ²/ g, the median size of the offspring of intermediate alumina is 0.01～5 μ m, and specific surface area is 30～300m ²/ g.

7, grinding Liquid composition according to claim 3, wherein the median size of the offspring of Alpha-alumina is 0.01～2 μ m, and specific surface area is 0.1～50m ²/ g, the median size of the offspring of intermediate alumina is 0.01～5 μ m, and specific surface area is 30～300m ²/ g.

8, grinding Liquid composition according to claim 1, wherein acid is polyprotonic acid.

9, grinding Liquid composition according to claim 2, wherein acid is polyprotonic acid.

10, grinding Liquid composition according to claim 3, wherein acid is polyprotonic acid.

11, grinding Liquid composition according to claim 5, wherein acid is polyprotonic acid.

12, grinding Liquid composition according to claim 1, it contains pK1 is acid more than 2.5 less than 2.5 acid and pK1.

13, grinding Liquid composition according to claim 2, it contains pK1 is acid more than 2.5 less than 2.5 acid and pK1.

14, grinding Liquid composition according to claim 3, it contains pK1 is acid more than 2.5 less than 2.5 acid and pK1.

15, grinding Liquid composition according to claim 5, it contains pK1 is acid more than 2.5 less than 2.5 acid and pK1.

16, grinding Liquid composition according to claim 8, it contains pK1 is acid more than 2.5 less than 2.5 acid and pK1.

17, reduce the method for the external waviness that is ground substrate, it has the operation of being ground substrate with the described grinding Liquid composition grinding of claim 1.

18, the manufacture method of substrate, it has the operation of grinding quilt grinding substrate with the described grinding Liquid composition of claim 1.