JP2006136996A - Polishing composition manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for economically manufacturing polishing composition in which the surface roughness of an object after polishing is small, and nano-scratches important in high density can be considerably reduced. <P>SOLUTION: The polishing composition manufacturing method comprises a step of filtering polishing composition before the refining by a depth-type filter to obtain intermediate filtrate (Step 1), and a step of filtering the intermediate filtrate by a pleat-type filter to obtain polishing composition (Step 2), wherein the fluctuation range of the filter inlet pressure in Step 1 is ≤ 50kPa. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a polishing composition.

  Recent memory hard disk drives are required to have a high capacity and a small diameter, and in order to increase the recording density, the flying height of the magnetic head is reduced to reduce the unit recording area. Accordingly, the surface quality required after polishing in the manufacturing process of the magnetic disk substrate is becoming stricter year by year. That is, it is necessary to reduce the surface roughness, micro waviness, roll-off and protrusions according to the low flying height of the head, and the allowable number of scratches per substrate surface is small according to the decrease in the unit recording area, Its size and depth are getting smaller and smaller.

  Also in the semiconductor field, high integration and high speed are advancing. In particular, miniaturization of wiring is required for high integration. As a result, in the manufacturing process of a semiconductor substrate, the depth of focus when exposing to a photoresist becomes shallow, and further surface smoothness is desired.

In response to such demands, for the purpose of improving surface smoothness, a polishing slurry having a reduced number of coarse particles and a method for producing the same are proposed in order to reduce scratches (scratches) generated on the surface of the object to be polished. (Patent Documents 1 to 3).
However, even if the above method is used, it is insufficient to obtain a polishing composition that can cope with higher density such as higher capacity and higher integration.
Japanese Patent Laid-Open No. 2003-188122 JP 2002-97387 A Japanese Patent Laid-Open No. 11-57454

  An object of the present invention is to provide a method capable of economically producing a polishing composition that has a small surface roughness of an object to be polished and can significantly reduce nanoscratches that are important in increasing the density. There is to do.

That is, the gist of the present invention is a method for producing a polishing liquid composition having the following purification step, wherein the fluctuation range of the filter inlet pressure in step 1 is 50 kPa or less (step 1). A step of filtering the pre-purification polishing composition with a depth filter to obtain an intermediate filtrate, and (step 2) a step of filtering the intermediate filtrate with a pleated filter to obtain a polishing composition.
About.

  By using the manufacturing method of the present invention, for example, when used in a polishing process of a precision component substrate for high density or high integration, fine nano scratches can be remarkably reduced, and high quality with excellent surface properties. The polishing liquid composition capable of producing precision component substrates such as memory hard disk substrates and semiconductor element substrates can be produced without impairing productivity.

The method for producing a polishing liquid composition of the present invention is a method for producing a polishing liquid composition having the following purification step, wherein the fluctuation range of the filter inlet pressure in step 1 is 50 kPa or less. This is a method for producing a composition, which can significantly reduce nanoscratches that cause defects and provide a substrate having excellent surface smoothness.
(Step 1) A step of filtering the pre-purification polishing composition with a depth filter to obtain an intermediate filtrate, and (Step 2) a step of filtering the intermediate filtrate with a pleated filter to obtain a polishing composition.

  This nano-scratch is a physical property that is important for high density or high integration especially in a memory hard disk substrate or a semiconductor device substrate. Therefore, by using the polishing composition obtained in the present invention, a high-quality memory hard disk substrate or semiconductor element substrate having excellent surface properties can be produced.

  The nano-scratch in the present invention is a fine flaw on the substrate surface having a depth of 10 nm or more and less than 100 nm, a width of 5 nm or more and less than 500 nm, and a length of 100 μm or more, and is detected by an atomic force microscope (AFM). It can be quantitatively evaluated as the number of scratches by measurement with “MicroMax” which is a visual inspection apparatus described in the examples described later.

  The nano scratch is a surface defect that has not been detected conventionally. That is, when a conventionally known method is used, the quality of the substrate is insufficient for higher density such as higher capacity and higher integration. As a result of intensive studies by the inventors of the present invention, it has been found for the first time that the reduction of “nano scratches” that could not be detected is insufficient.

  Although the mechanism for reducing nanoscratches in the present invention is not clear, since polishing is performed by sandwiching a substrate with a polishing pad and applying a constant load, aggregates of abrasive primary particles contained in the polishing liquid composition or coarse polishing It is considered that the primary particles receive a local load under the polishing pressure, come into contact with the surface of the object to be polished and are pushed into the substrate surface, and deep nano scratches are generated. In the present specification, the abrasive particles in the polishing liquid composition include not only primary particles but also aggregated particles obtained by aggregating primary particles.

  Therefore, it has been clarified that the nano-scratch can be reduced by reducing the coarse abrasive particles having a specific size present in the polishing composition, but the conventional known technique sufficiently reduces the coarse abrasive particles. Was not industrially made. For example, in the process of filtering with a screen type filter such as a membrane filter, although aggregates of abrasive particles or coarse abrasive particles can be removed, they cannot be used industrially. In addition, in the filtration process using only a depth type filter, the removal of aggregates of abrasive particles or coarse abrasive particles is insufficient, and thus the reduction of nano scratches is not sufficient. Although the removal of the aggregates or coarse abrasive particles is sufficient, the coarse particles cause clogging, and it is difficult to economically obtain a purified polishing composition.

  In the present invention, a polishing composition capable of significantly reducing nanoscratches by filtering using a depth-type filter and then a pleat-type filter, and adjusting the fluctuation range of the depth-type filter inlet pressure to a specific range for filtration. Can be obtained economically.

  Here, in filter filtration, when the effective opening of the filter medium is widened by pressurization, coarse particles that have been collected or should be collected may pass through the filter. The separation of fibers etc. may lead to a decrease in filtration accuracy. In order to prevent these phenomena, it is generally recommended by each filter manufacturer to manage the differential pressure between the filter inlet pressure and the outlet pressure below a certain value. However, even when this differential pressure is controlled below a certain value, the filtration accuracy is often lowered. Therefore, as a result of diligent investigation, the applicants surprisingly found that when the pulsation of the liquid feeding occurs during the liquid feeding, the fluctuation range of the filter inlet pressure becomes large, and the filtration accuracy due to the same factors as described above is increased. It was found to cause a decrease.

  Therefore, as a result of further diligent examination, the present applicant conducted filtration of the depth type filter and then the pleated type filter, and kept the fluctuation range of the inlet pressure of the depth type filter within a certain value, thereby reducing the polishing composition. In this manufacturing process, it is possible to increase the collection efficiency and accuracy of coarse particles of the filter, and for the first time, it is found that even a polishing composition in which the amount of coarse particles is extremely strictly controlled as in the present invention can be produced. It was.

  In the present invention, the fluctuation range of the depth type filter inlet pressure refers to the difference between the maximum value and the minimum value of the pressure applied to the filter during liquid feeding. This fluctuation range is a value in all depth filters.

  The fluctuation range of the depth filter inlet pressure in step 1 is 50 kPa or less, and is preferably 40 kPa or less, more preferably 30 kPa or less, from the viewpoint of reducing the coarse particle removal load in step 2 due to the improvement of filtration accuracy. The fluctuation range of the filter inlet pressure can be measured by, for example, using a pressure gauge attached to the filter housing and reading the maximum value and the minimum value of the pressure during liquid feeding.

  One method of reducing the pressure fluctuation range is to reduce the pulsation generated from the liquid feed pump. For example, a method of feeding with a non-pulsation pump with small pulsation, or preventing pulsation of the liquid feed pump. For this purpose, a method of installing a pressure buffering device such as a damper at the pump outlet can be used. In addition, there is a method of increasing the volume of piping in order to reduce the pulsation of the object to be filtered between the liquid feed pump and the filter inlet, for example, a method of installing an accumulator or the like between the pump outlet and the filter, A method of taking a long pipe between the pump and the filter or increasing the pipe diameter can be used. In addition, the pressure fluctuation range can be further reduced by combining them individually or appropriately according to the filtration device and the filtration conditions.

  In the polishing composition purification step, the depth type filter in step 1 includes a bag type filter (Sumitomo 3M Co., Ltd.) and a cartridge type filter (Advantech Toyo Co., Nippon Pole Co., CUNO Co., Daiwabo Co., Ltd.). Can be used.

  The depth type filter has a characteristic that the pore structure of the filter medium is rough at the inlet, finer at the outlet, and continuously or stepwise as it goes from the inlet to the outlet. That is, among coarse particles, large particles are collected in the vicinity of the inlet side, and small particles are collected in the vicinity of the outlet side, so that effective filtration is possible. The shape of the depth filter may be a bag-like bag type or a hollow cylindrical cartridge type. In addition, a filter material having the above-described characteristics, which is simply processed into a pleat shape, is classified as a depth filter because it has a function of a depth filter.

  In step 1, a depth filter may be used in one stage, or may be used in combination (for example, arranged in series) in multiple stages. Moreover, you may use combining a bag type and a cartridge type. In multi-stage filtration, the filter pore size and the structure of the filter medium are appropriately selected according to the number of abrasive particles having a particle size of 0.56 μm or more and less than 1 μm in the pre-purification polishing composition, and the processing order of the filter is further selected By selecting this, it is possible to improve the particle size control (filtration accuracy) and economy of coarse particles to be removed. That is, when a filter having a large pore structure is used upstream (upstream) of a fine filter, there is an effect that the lifetime of the filter can be extended as a whole manufacturing process.

As the pleated filter in the process 2, generally, the filter medium is formed into a pleated shape and formed into a hollow cylindrical cartridge type (Advantech Toyo, Nippon Pole, CUNO, Daiwabo, etc.) Unlike a depth type filter that collects at each part in the thickness direction, the pleated filter is said to be mainly collected on the filter surface because the filter material is thin. It is characterized by high filtration accuracy.
The pleated filter used in step 2 may be used in one stage, or may be used in combination (for example, arranged in series) in multiple stages. In addition, in the multistage filtration, the filter pore size and the structure of the filter medium are appropriately selected according to the number of abrasive particles having a particle size of 0.56 μm to less than 1.0 μm in the intermediate filtrate after step 1, and the filter By appropriately selecting the treatment order, the productivity of the polishing composition in the present invention can be improved. That is, if a filter having a large pore structure is used upstream (upstream) of a fine filter, the life of the filter can be extended as a whole. Furthermore, the filter used later can stabilize the quality in polishing liquid composition more by making the filter of the same hole diameter into a multistage.

  In the entire filtration process, when a pleated filter is used after using a depth filter, the life of the filter can be extended as a whole, and the polishing composition in the present invention can be produced economically.

  The pore size of these depth type filters and pleated type filters is generally expressed as a filtration accuracy capable of removing 99%. For example, a pore size of 1.0 μm indicates a filter capable of removing 99% of particles having a diameter of 1.0 μm.

  The pore size of the depth filter used in step 1 of the present invention is preferably 5.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.0 μm or less, from the viewpoint of reducing the coarse particle removal load in step 2. It is.

In addition, when the depth type filter used in Step 1 is multistage (for example, arranged in series), if the final filter has a pore size of sub-micron or less, the coarse particle removal load in Step 2 is further reduced, resulting in more production. It is possible to improve the performance.
The pore size of the pleated filter used in step 2 of the present invention is preferably 1.0 μm or less, more preferably 0.8 μm or less, still more preferably 0.6 μm or less, and still more preferably 0.8 μm or less from the viewpoint of reducing coarse particles. 5 μm or less.

The number of abrasive particles having a particle size of 0.56 μm or more and less than 1 μm in the intermediate filtrate after step 1 is preferably 1,000,000 or less per cm ³ , and more preferably from the viewpoint of reducing the number of particles removed in step 2 Is 800,000 or less, more preferably 700,000 or less, more preferably 600,000 or less.
The number of abrasive particles having a particle size of 0.56 μm or more and less than 1 μm in the polishing composition after Step 2 is preferably 500,000 or less per cm ³ , and more preferably 400,000 or less from the viewpoint of reducing nanoscratches. More preferably, it is 300,000 or less, more preferably 200,000 or less, and still more preferably 100,000 or less.

  The abrasive particle size (particle size) in the polishing composition can be a number counting method (Sizing Particle Optical Sensing method), for example, Accusizer 780 and Coulter manufactured by Particle Sizing Systems, USA. It can be measured by a Coulter counter manufactured by (Coulter).

  The filtration method in step 1 and step 2 may be a recirculation type that repeatedly filters or a one-pass method. Alternatively, a batch method that repeats the one-pass method may be used. In order to pressurize, the liquid passing method preferably uses a pump in the circulation type, and uses a pump in the one-pass method. In addition, a pressure filtration with a small fluctuation range of the filter inlet pressure by introducing air pressure or the like into the tank. Can be used.

The intermediate filtrate to be used in Step 2 preferably has 1,000,000 or less abrasive particles having a particle size of 0.56 μm or more and less than 1 μm per 1 cm ^3. A general dispersion or particle removal step may be provided before and / or after step 1. For example, a dispersion method using a high-pressure dispersion device such as a high-speed dispersion device or a high-pressure homogenizer, or a sedimentation method using a centrifugal separator or the like can be used. When processing using these, each may be processed independently or may be processed in combination of two or more, and there is no limitation on the processing order of the combination. Further, the processing conditions and the number of processing times can be appropriately selected and used.

As the supply pressure to the filter in the step 1 and the step 2, it is preferable to perform filtration at a pressure equal to or lower than the pressure recommended for the filter to be used from the viewpoint of filtration accuracy. In addition, the differential pressure between the filter inlet pressure and the outlet pressure is preferably controlled to be a certain value or less because the effective pressure of the filter medium is increased and the filtration accuracy is reduced by increasing the differential pressure. .
The differential pressure of the depth filter in step 1 is preferably 200 kPa or less, more preferably 170 kPa or less, and even more preferably 150 kPa or less from the viewpoint of filtration accuracy. The differential pressure of the pleated filter in step 2 is preferably 250 kPa or less, more preferably 200 kPa or less, and still more preferably 170 kPa or less from the viewpoint of filtration accuracy. The differential pressure applied to the filter at the time of liquid feeding can be obtained from the difference between the average values using, for example, inlet and outlet pressure gauges attached to the filter housing.
In addition, there is no limitation in particular as filtration conditions other than the above in process 1 and 2.

  The pre-purification polishing composition used in the present invention refers to a composition containing an abrasive containing abrasive particles before being subjected to Step 1, for example, an abrasive, water, if necessary, The thing manufactured by mixing the other component which can be mix | blended with the below-mentioned polishing liquid composition is mentioned. Further, the state of the polishing composition before purification is preferably a state in which abrasive particles are dispersed.

  In this invention, a polishing liquid composition can be manufactured by using the polishing liquid composition before refinement | purification to process 1 and 2. Specifically, an abrasive, water, and other components produced by mixing are used for Steps 1 and 2, or a pre-purification polishing composition containing an abrasive and water is used in Steps 1 and 2 above. After being subjected to 2, the polishing composition can be produced by mixing other components with the obtained filtrate.

  As the abrasive used in the present invention, those generally used for polishing can be used, such as metal, metal or metalloid carbide, nitride, oxide, boride, diamond, etc. Is mentioned. 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 the abrasive include silicon oxide (hereinafter also referred to as silica), aluminum oxide (hereinafter also referred to as alumina), silicon carbide, diamond, manganese oxide, magnesium oxide, zinc oxide, and titanium oxide (hereinafter also referred to as titania). ), Cerium oxide (hereinafter also referred to as ceria), zirconium oxide, and the like. Use of one or more of these is preferable from the viewpoint of improving the polishing rate. Among these, silica, alumina, titanium oxide, ceria, zirconium oxide, and the like are suitable for polishing precision component substrates such as semiconductor element substrates and magnetic recording medium substrates.

  Among them, as the abrasive particles, colloidal particles and fumed particles are preferable from the viewpoint of reducing nano scratches that cause surface defects, and colloidal particles are preferable. And colloidal silica particles are more suitable. The colloidal silica particles can be obtained, for example, by a production method in which the colloidal silica particles are generated from a silicic acid aqueous solution. In addition, those obtained by surface modification or surface modification of these abrasive particles with functional groups, those obtained by compounding with surfactants or other abrasives, and the like can also be used.

  The average particle size of the primary particles of the abrasive is preferably 1 to 50 nm from the viewpoint of reducing nanoscratches and the surface roughness (centerline average roughness: Ra, Peak to Valley value: Rmax). From the viewpoint of simultaneously improving the polishing rate, the thickness is more preferably 3 to 50 nm, further preferably 5 to 40 nm, and further preferably 5 to 30 nm.

  The average particle size of the primary particles of the abrasive can be obtained as an average particle size when measured by each method by a method obtained from an observation image with a transmission electron microscope (TEM), a titration method, or a BET method. .

  The content of the abrasive in the polishing composition at the time of use is preferably 0.5% by weight or more, more preferably 1% by weight or more, further preferably 3% by weight or more, from the viewpoint of improving the polishing rate. Preferably, it is 5% by weight or more, and from the viewpoint of economically improving the surface quality, it is preferably 20% by weight or less, more preferably 15% by weight or less, further preferably 13% by weight or less, and further preferably 10% by weight. % Or less. Therefore, from the viewpoint of improving the polishing rate and economically improving the surface quality, the content is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and further preferably 3 to 13% by weight. %, More preferably 5 to 10% by weight. The content of the abrasive may be either the content at the time of producing the polishing liquid composition or the content at the time of use. Usually, it is produced as a concentrated solution, and this is often used after being diluted. .

  Examples of water used in the present invention include ion exchange water, distilled water, and ultrapure water. The water content corresponds to the balance obtained by removing the abrasive and other components from 100% by weight, preferably 60 to 99% by weight, and more preferably 80 to 97% by weight.

  Although there is no restriction | limiting in particular about pH of the polishing liquid composition manufactured in this invention, When using the said polishing liquid composition as an abrasive | polishing material, it is preferable to use pH at 0.1-7. In alkalinity, nano-scratches tend to occur more easily than acidity. The generation mechanism is not clear, but in an alkaline atmosphere in which abrasive particles repel each other due to surface charges, aggregates of abrasive primary particles or coarse abrasive primary particles contained in the polishing composition are dense in the polishing part. It is presumed that it is not possible to perform proper filling and is likely to receive a local load under the polishing pressure. The pH is preferably determined according to the type of the object to be polished and the required characteristics. When the material of the object to be polished is a metal material, the pH is preferably 6 or less, more preferably 5 from the viewpoint of improving the polishing rate. Hereinafter, it is more preferably 4 or less. Further, from the viewpoint of the influence on the human body and the prevention of corrosion of the polishing apparatus, the pH is preferably 0.5 or more, more preferably 1 or more, and still more preferably 1.4 or more. In particular, in the case of a precision component substrate whose material to be polished is a metal material, such as a nickel-phosphorus (Ni-P) plated aluminum alloy substrate, the pH is 0.5 to 6 in consideration of the above viewpoint. More preferably, it is 1.0-5, More preferably, it is 1.4-4.

  As the polishing composition in the present invention, a composition whose pH is appropriately adjusted according to the stable state and surface modification state of the abrasive can be used. For example, it can adjust with the following acids, salts, or alkalis. Specifically, inorganic acids such as nitric acid, sulfuric acid, nitrous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid, or salts thereof, 2-amino Ethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane- 1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2- Diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane- , 3,4-tricarboxylic acid, organic phosphonic acids such as α-methylphosphonosuccinic acid or their salts, aminocarboxylic acids such as glutamic acid, picolinic acid, aspartic acid or their salts, oxalic acid, nitroacetic acid, maleic acid And carboxylic acids such as oxaloacetic acid or salts thereof. Of these, inorganic acids or organic phosphonic acids and their salts are preferred from the viewpoint of reducing nanoscratches.

  Among inorganic acids or salts thereof, nitric acid, sulfuric acid, hydrochloric acid, perchloric acid or salts thereof are more preferable. Among organic phosphonic acids or salts thereof, 1-hydroxyethylidene-1,1-diphosphone is preferred. More preferred are acids, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) or salts thereof. These acids or their salts may be used alone or in admixture of two or more.

  The counter ion (cation) of these salts is not particularly limited, and specific examples include salts with metal ions, ammonium ions, and alkylammonium ions. Specific examples of the metal include metals belonging to 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or Group 8 of the periodic table (long period type). From the viewpoint of reducing nanoscratches, ammonium ions or metal ions belonging to Group 1A are preferred.

  Moreover, other components can be mix | blended with the polishing liquid composition in this invention as needed. For example, a thickener, a dispersant, a rust inhibitor, a basic substance, a surfactant, and the like can be given. Moreover, although it cannot generally limit by the material of to-be-polished material, generally an oxidizing agent can be added with a metal material from a viewpoint of improving a grinding | polishing rate. Examples of the oxidizing agent include hydrogen peroxide, permanganic acid, chromic acid, nitric acid, peroxo acid, oxyacid, or salts thereof and oxidizing metal salts.

Among them, the polishing composition after step 2 preferably satisfies the following conditions from the viewpoint of reducing nanoscratches:
(1) Abrasive particles having a particle diameter of 1 μm or more are 0.001% by weight or less based on all abrasive particles in the polishing liquid composition, and (2) Abrasive particles having a particle diameter of 3 μm or more are totally polished in the polishing liquid composition. 0.0008% by weight or less based on the particles.

  The polishing liquid composition obtained by the production method of the present invention is supplied, for example, between a non-woven organic polymer polishing cloth or the like (polishing pad) and the substrate to be polished, that is, the polishing liquid composition is polished. The substrate is supplied to a substrate polishing surface sandwiched between polishing pads with a pad attached thereto, and is used in the polishing step while contacting the substrate by moving the polishing plate and / or the substrate under a predetermined pressure. This polishing can remarkably suppress the generation of nanoscratches.

  The polishing liquid composition is particularly suitable for the production of precision component substrates. For example, it is suitable for polishing precision component substrates such as substrates of magnetic recording media such as magnetic disks and magneto-optical disks, optical disks, photomask substrates, optical lenses, optical mirrors, optical prisms, and semiconductor substrates. In the manufacture of a semiconductor substrate, the manufacturing method of the present invention is used in a polishing process of a silicon wafer (bare wafer), a formation process of a buried element isolation film, a planarization process of an interlayer insulating film, a formation process of a buried metal wiring, a formation process of a buried capacitor, etc. The polishing liquid composition obtained in (1) can be used.

  The polishing composition obtained by the production method 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.

  Suitable materials for the polishing object using the polishing composition obtained by the production method of the present invention include, for example, metals or semi-metals such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, or the like. Examples thereof include glassy substances such as alloys, glass, glassy carbon, and amorphous carbon, ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride, and titanium carbide, and resins such as polyimide resins. Among these, it is suitable for an object to be polished containing a metal such as aluminum, nickel, tungsten, or copper and an alloy mainly composed of these metals. For example, a Ni—P plated aluminum alloy substrate or a glass substrate such as crystallized glass or tempered glass is more suitable, and a Ni—P plated aluminum alloy substrate is more suitable.

  There is no particular limitation on the shape of the object to be polished. For example, the polishing liquid composition of the present invention has a shape having a flat portion such as a disk shape, a plate shape, a slab shape, a prism shape, or a shape having a curved surface portion such as a lens. Things are used. Among them, it is excellent for polishing a disk-shaped workpiece.

  The surface roughness, which is a measure of surface smoothness, is not limited in its evaluation method, but for example, it is evaluated as a roughness that can be measured at a short wavelength of 10 μm or less in an atomic force microscope (AFM), and the center line average It can be expressed as roughness Ra (AFM-Ra). The polishing composition of the present invention is suitable for a polishing process for a magnetic disk substrate, and further for a polishing process for reducing the surface roughness (AFM-Ra) of the substrate after polishing to 2.0 mm or less.

  In the production process of the substrate, when there are a plurality of polishing processes, it is preferable to use the polishing liquid composition obtained by the production method of the present invention after the second process, which significantly reduces nanoscratches and has an excellent surface. From the viewpoint of obtaining smoothness, it is particularly preferably used in the finish polishing step. The finish polishing process refers to at least one final polishing process when there are a plurality of polishing processes.

  At that time, in order to avoid mixing of the polishing material and polishing liquid composition in the previous process, different polishing machines may be used, and when different polishing machines are used, a substrate is provided for each process. It is preferable to wash. The polishing machine is not particularly limited. The substrate manufactured in this way has nano scratches remarkably reduced and is excellent in surface smoothness. That is, the surface roughness after polishing (AFM-Ra) is, for example, 2.0 mm or less, preferably 1.8 mm or less, more preferably 1.5 mm or less.

  The surface property of the substrate before being subjected to the polishing step using the polishing composition after step 2 of the present invention is not particularly limited. For example, a substrate having a surface property with an AFM-Ra of 10 mm or less is suitable.

  The abrasive used in the production of such a substrate may be the same as that used in the polishing composition of the present invention. The polishing step is preferably performed after the second step among the plurality of polishing steps, and particularly preferably performed in the finish polishing step.

  The substrate produced as described above has excellent surface smoothness and a surface roughness (AFM-Ra) of, for example, 2.0 mm or less, preferably 1.8 mm or less, more preferably 1.5 mm or less. can get.

Further, the manufactured substrate has very few nano scratches. Therefore, when the substrate is, for example, a memory hard disk substrate, it is possible to cope with a recording density of 120 G bits / inch ² and further 160 G bits / inch ² , and when it is a semiconductor substrate, A wiring width of 65 nm or even 45 nm can be handled.

As a substrate to be polished, a Ni-P plated aluminum alloy substrate having an outer diameter of 95 mmφ and an inner diameter of 25 mmφ having a thickness of 1.27 mm and roughly polished with a polishing liquid containing an alumina abrasive in advance and having an AFM-Ra of 10 mm. Polishing evaluation was performed.
As an evaluation index of productivity in filtration, when at least 200 kg of polishing composition can be filtered without clogging, the productivity evaluation is acceptable, and when clogging occurs within 200 kg and filtration becomes difficult, at that time Table 1 shows the filtration amount.
In addition, the differential pressure of the filter in an Example and a comparative example was controlled by the amount of liquid flow so that a depth type filter might be 150 kPa or less, and a pleat type filter might be 160 kPa or less.

Example 1
As a pre-purification polishing composition, colloidal silica slurry (manufactured by DuPont, average particle size of primary particles of 20 nm, silica particle concentration of 40% by weight, number of abrasive particles of 0.587 μm or more and less than 1 μm, 6,875,000 / cm ³ ) was used. Yamada diaphragm pump (model number DP-10BT) is used as the pump, and a pulsation damper (model number AD-10ST) manufactured by Yamada Corporation is used at the outlet, and a 10m Tetron blade hose (outer diameter 18mm, inner diameter 12mm) is connected to the depth filter. ) And a bag-type depth filter (Sumitomo 3M, “Liquid Filter 522”) with a pressure gauge installed directly in the housing as a filter. Two 250 mm “TCP-JX” (pore diameter 1.0 μm) manufactured by Advantech Toyo Co., Ltd. were placed in series, and filtered under the condition of an average liquid flow rate of 10.3 kg / min to obtain a polishing liquid composition a. At this time, the pressure fluctuation range of the depth type filter was 30 kPa, and clogging did not occur when the filtration amount was 200 kg. A predetermined amount of 35% by weight of hydrogen peroxide water (manufactured by Asahi Denka) and 60% by weight of HEDP (1-hydroxyethylidene-1,1-diphosphonic acid) aqueous solution in ion-exchanged water so that the concentrations shown in Table 1 are obtained. (Solucia Japan) and 95% by weight sulfuric acid (Wako Pure Chemical Industries, Ltd.) were added, and while stirring the mixed aqueous solution, the polishing composition a was added to obtain a polishing composition a ′.

Example 2
The same pre-purification polishing composition, diaphragm pump, damper, tetron blade hose, and bag-type depth filter as in Example 1 were used in the same manner. Next to the bag-type depth filter, one cartridge-type depth filter “TCPD-03A” (pore diameter 3.0 μm) manufactured by Advantech Toyo Co., Ltd. 250 mm in length, and then as a pleated filter, Advantech Toyo Co., Ltd. 250 mm in length Two “TCP-JX” (pore diameter: 1.0 μm) manufactured in series were arranged in series and filtered under the condition of an average liquid flow rate of 8.1 kg / min to obtain a polishing composition b. At this time, the pressure fluctuation range of the depth type filter was 35 kPa, and clogging did not occur when the filtration amount was 200 kg. Using the obtained polishing liquid composition b, a polishing liquid composition b ′ was obtained in the same manner as in Example 1.

Example 3
The same pre-purification polishing composition, diaphragm pump, damper, tetron blade hose, and bag-type depth filter as in Example 1 were used in the same manner. Next to the bag-type depth filter, as a cartridge-type depth-type filter, 250 mm long “TCPD-03A” (pore diameter: 3.0 μm) manufactured by Advantech Toyo Co., Ltd., Japan Pole “profile II-010” (pore diameter: 1.0 μm) ), And two “TCYE-HS” (pore diameter 0.65 μm) manufactured by Advantech Toyo Co., Ltd. with a length of 250 mm are arranged in series as a pleated filter, and filtered under the condition of an average liquid flow rate of 5.2 kg / min. A polishing liquid composition c was obtained. At this time, the pressure fluctuation range of the depth type filter was 32 kPa, and clogging did not occur when the filtration amount was 200 kg. Using the obtained polishing composition c, a polishing composition c ′ was obtained in the same manner as in Example 1.

Example 4
The same pre-purification polishing composition, diaphragm pump, damper, tetron blade hose, and bag-type depth filter as in Example 1 were used in the same manner. Next to the bag-type depth filter, as a cartridge-type depth-type filter, “Profile II-020” (pore diameter 2.0 μm) manufactured by Nippon Pole Co., Ltd., having a length of 250 mm, “Profile II-005” (pore size 0. 5 μm), and two “TCYE-HS” (pore diameter 0.65 μm) manufactured by Advantech Toyo Co., Ltd., having a length of 250 mm, are arranged in series as a pleated filter, and the average liquid flow rate is 6.4 kg / min. Thus, a polishing liquid composition d was obtained. At this time, the pressure fluctuation range of the depth type filter was 21 kPa, and clogging did not occur when the filtration amount was 200 kg. Using the polishing composition d thus obtained, a polishing composition d ′ was obtained in the same manner as in Example 1.

Example 5
The same pre-purification polishing composition, diaphragm pump, damper, tetron blade hose, and bag-type depth filter as in Example 1 were used in the same manner. As a step of obtaining an intermediate filtrate, first, the polishing composition before purification was filtered with a bag-type depth filter under the condition of an average liquid flow rate of 15.3 kg / min. At this time, the variation range of pressure in the depth type filter was 39 kPa, and the amount of filtration was 250 kg. The obtained primary filtrate is rotated using a KS type ultra-high speed centrifuge (manufactured by Kansai centrifuge, model number: U1-160, rotating cylinder size Φ105 × length 730 mm, maximum solid content holding amount about 6 L). The treatment was performed under the conditions of several 18500 r / min, centrifugal acceleration 20000 G, and average liquid flow rate 12.5 kg / min. This intermediate filtrate is put into a pressurizable 1M ³ stainless steel tank, and two “TCP-JX” (pore diameter 1.0 μm) made by Advantech Toyo Co., Ltd. with a length of 250 mm are connected in series as a pleated filter to the tank outlet line. It installed and filtered under the pressurization conditions of a pressure of 1.7 kg / cm < ² >, and the polishing liquid composition e was obtained. No clogging occurred when the filtration amount was 200 kg. Using the obtained polishing liquid composition e, a polishing liquid composition e ′ was obtained in the same manner as in Example 1.

Comparative Example 1
About the polishing composition before refinement | purification and a bag-type depth type filter, the same thing as Example 1 was used. Yamada's diaphragm pump (Model No. DP-10BT), 2m Tetron blade hose (outer diameter 18mm, inner diameter 12mm) is used as a pipe to the depth type filter, and the pleat type is next to the bag type depth type filter. Two “TCP-JX” (pore diameter 1.0 μm) manufactured by Advantech Toyo Co., Ltd. with a length of 250 mm were installed in series as a filter, and filtered under the condition of an average liquid flow rate of 12.6 kg / min. Obtained. At this time, the pressure fluctuation range of the depth type filter was 75 kPa, and clogging did not occur when the filtration amount was 200 kg. Using the resulting polishing liquid composition f, a polishing liquid composition f ′ was obtained in the same manner as in Example 1.

Comparative Example 2
The same pre-purification polishing composition, diaphragm pump, damper, tetron blade hose, and bag-type depth filter as in Example 1 were used in the same manner. A polishing liquid composition g was obtained by filtering with a bag-type depth filter alone under the condition of an average liquid flow rate of 13.5 kg / min. At this time, the fluctuation range of the pressure applied to the depth type filter was 50 kPa, and clogging did not occur when the filtration amount was 200 kg. Using the obtained polishing composition g, a polishing composition g ′ was obtained in the same manner as in Example 1.

Comparative Example 3
About the polishing liquid composition before refinement | purification, the diaphragm pump, the damper, and the Tetron blade hose, the same thing as Example 1 was used similarly. As a pleated filter, two “TCP-JX” (pore diameter 1.0 μm) manufactured by Advantech Toyo Co., Ltd. with a length of 250 mm are installed in series and filtered under the condition of an average liquid flow rate of 8.9 kg / min. Got. The fluctuation range of the pleat type filter inlet pressure at this time was 45 kPa, and clogging occurred when the filtration amount was 43 kg. Using the obtained polishing composition h, a polishing composition h ′ was obtained in the same manner as in Example 1.

Comparative Example 4
About the polishing liquid composition before refinement | purification, the diaphragm pump, the damper, and the Tetron blade hose, the same thing as Example 1 was used similarly. As a pleated filter, two “TCYE-HS” (pore diameter 0.65 μm) manufactured by Advantech Toyo Co., Ltd. having a length of 250 mm are installed in series, and a polishing liquid composition i is obtained under the condition of an average flow rate of 7.5 kg / min. It was. The fluctuation range of the pleat type filter inlet pressure at this time was 61 kPa, and clogging occurred when the filtration amount was 20 kg. Using the resulting polishing liquid composition i, a polishing liquid composition i ′ was obtained in the same manner as in Example 1.

  Next, polishing was performed under the following conditions using the polishing liquid compositions a ′ to i ′ obtained in Examples 1 to 5 and Comparative Examples 1 to 4, and nano scratches were evaluated.

1. Polishing conditions / polishing tester: Speedfam, double-sided 9B polisher / polishing pad: Fujibow, urethane finish polishing pad / upper plate rotation speed: 32.5 r / min
Polishing liquid composition supply amount: 100 mL / min
・ Main polishing time: 4 min
-Final polishing load: 7.8 kPa
・ Number of loaded substrates: 10

2. Measuring conditions and measuring equipment for abrasive particles: “Accurizer 780APS” manufactured by PSS
・ Injection Loop Volume: 1mL
-Flow rate: 60 mL / min
・ Data Collection Time: 60sec
・ Number of channels: 128

3. Nano scratch measurement conditions / measurement equipment: “MicroMax VMX-2100CSP” manufactured by VISION PSYTEC
-Light source: 100% for both 2Sλ (250W) and 3Pλ (250W)
-Tilt angle: -6 °
・ Magnification: Maximum (Field range: 1/120 of the total area)
・ Observation area: total area (substrate with outer circumference 95mmφ and inner circumference 25mm)
・ Iris: notch

Evaluation: Randomly select 4 out of the substrates put in the polishing tester, and divide the total number of nano scratches (on each side) of each of the 4 substrates by 8 to get The number of nano scratches was calculated. Moreover, the evaluation of the nanoscratches described in Table 1 was performed by relative evaluation with respect to the number of nanoscratches (lines / surface) of Comparative Example 1.

  From the results of Table 1, the polishing liquid compositions a ′ to e ′ obtained in Examples 1 to 5 are more productive than the polishing liquid compositions f ′ to i ′ obtained in Comparative Examples 1 to 4. It can be seen that nanoscratches can be significantly reduced well.

  The method for producing a polishing composition of the present invention can be used, for example, in a polishing step of a precision component substrate for high density or high integration.

Claims (5)

The manufacturing method of the polishing liquid composition which has the following purification processes, Comprising: The fluctuation range of the filter inlet pressure in the process 1 is 50 kPa or less.
(Step 1) A step of filtering the pre-purification polishing composition with a depth filter to obtain an intermediate filtrate, and (Step 2) a step of filtering the intermediate filtrate with a pleated filter to obtain a polishing composition. The method for producing a polishing composition according to claim 1, wherein the number of abrasive particles having a particle size of 0.56 µm or more and less than 1 µm in the intermediate filtrate after step 1 is 1,000,000 or less per 1 cm ³ . The method for producing a polishing composition according to claim 1 or 2, wherein the polishing composition after step 2 has 500,000 or less abrasive particles having a particle size of 0.56 µm or more and less than 1 µm per cm ³ . The method for producing a polishing composition according to any one of claims 1 to 3, wherein the number of abrasive particles having a particle size of 0.56 µm or more and less than 1 µm in the intermediate filtrate to be provided in Step 2 is 1,000,000 or less per 1 cm ³ . The manufacturing method of the polishing liquid composition in any one of Claims 1-4 with which the polishing liquid composition after the process 2 satisfy | fills the following conditions:
(1) Abrasive particles having a particle diameter of 1 μm or more are 0.001% by weight or less based on all abrasive particles in the polishing liquid composition, and (2) Abrasive particles having a particle diameter of 3 μm or more are totally polished in the polishing liquid composition. 0.0008% by weight or less based on the particles.