JP2006130638A - Encased abrasive material particle dispersed liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encased abrasive material particle dispersed liquid, remarkably reducing nano-scratch of material to be polished even in polishing after long-term storage independently of the storage period, and also to provide a polishing liquid kit including the encased abrasive material particle dispersed liquid. <P>SOLUTION: In this encased abrasive material particle dispersed liquid, the ratio of contact liquid area of polishing material particle dispersed liquid to the whole area of the wall surface in the case (contact liquid area)/(total wall surface area in the case) is 0.85 or more. This polishing liquid kit is composed of the encased abrasive material particle dispersed liquid, acid and/or its salt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a container-containing abrasive particle dispersion and a polishing liquid kit using the container-containing abrasive particle dispersion.

  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. Along with this, 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, a polishing liquid containing colloidal silica has been proposed in order to reduce the scratches (scratches, etc.) generated on the surface of the workpiece for the purpose of improving the surface smoothness (Patent Document). 1) is not mentioned at all about the container, storage conditions and the like.
JP 2002-327170 A

  An object of the present invention is not dependent on a storage period, and is a container-containing abrasive particle dispersion that can remarkably reduce nano-scratches of an object to be polished even after polishing after long-term storage, and the container-containing abrasive particle dispersion It is providing the polishing liquid kit containing a liquid.

The inventors of the present invention produced a solid product by evaporation and drying of water from the silica dispersion droplets adhering to the inner wall space of the container filled with the abrasive particle dispersion, and this was generated as an abrasive particle dispersion. When the abrasive particle dispersion is used as a polishing liquid, the solid matter is found to cause nanoscratch formation.
As a result of further investigation, it was found that the physical properties, particularly the action characteristics, of the abrasive particle dispersion can be maintained for a long time by adjusting the filling state of the abrasive particle dispersion in the container to a specific one. Completed the invention.
That is, the gist of the present invention is as follows.
[1] Ratio of the wetted area of the abrasive particle dispersion to the total area of the wall surface in the container (wetted area) / (total wall surface area in the container)
The present invention relates to a container-containing abrasive particle dispersion having an A of 0.85 or more, and [2] an abrasive liquid kit comprising the container-containing abrasive particle dispersion described in [1] above and an acid and / or a salt thereof.

  By using the container-containing abrasive particle dispersion of the present invention, for example, in a polishing step of a substrate for precision parts for high density or high integration, nano scratches can be remarkably reduced, so that the surface property is excellent. There is an effect that a precision component substrate such as a quality magnetic disk substrate or a semiconductor element substrate can be manufactured.

  As described above, the container-containing abrasive particle dispersion of the present invention has a ratio of the wall area in contact with the abrasive particle dispersion to the total area of the wall surface in the container [(wetted area) / (total wall surface in the container (Area)] is 0.85 or more, and has such a feature. By having such a feature, the nano-scratch of the object to be polished is remarkably reduced even in polishing after storage for a long period of time without depending on the storage period. The effect that it can be performed is produced.

  In the present invention, the “total wall surface area in the container” means the surface area of the entire wall surface of the inner surface of the container in which the abrasive particle dispersion can be placed (including a stopper part when the container has a stopper). . Further, the “wetted area” means the total wall surface area of the inner surface of the container in contact with the dispersion when the abrasive particle dispersion is placed in the container and the container is left standing. In addition, the total wall surface area and the liquid contact area in the container can be calculated by geometric calculation or by developing the container and measuring the dimensions. In this calculation, the surface of the container is assumed to be smooth, and irregularities of less than 1 mm are ignored.

  The ratio of the wetted area to the total wall surface area in the container is 0.85 or more, preferably 0.90 or more, more preferably 0.92 or more from the viewpoint of nanoscratch reduction, and also due to temperature rise. From the viewpoint of preventing the liquid from overflowing from the container due to the volume expansion of the dispersion, it is preferably 0.99 or less, more preferably 0.98 or less, and even more preferably 0.97 or less.

  In addition, the ratio of the liquid contact area to the total wall surface area in the container can be arbitrarily adjusted by the air filling in the container or the like in the case of a filling liquid amount in the container and a flexible bag (for example, polyethylene bag). .

  The nano-scratch in the present invention is a fine scratch on the substrate surface having a depth of 10 nm or more, less than 100 nm, a width of 5 nm or more, 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 by the number of nanoscratches by measurement with “MicroMax” manufactured by VISION PSYTEC, which is a visual inspection apparatus described in 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 has been insufficient.

In the present invention, the abrasive particle dispersion is a liquid in which abrasive particles are dispersed. As the abrasive, abrasives generally used for polishing can be used, for example, metal, metal or metalloid carbide, metal or metalloid nitride, metal or metalloid oxide, metal or Examples include metalloid borides and diamond. Examples of the metal or metalloid element include those belonging to Group 3A, 4A, 5A, 3B, 4B, 5B, 6A, 7A or Group 8 of the periodic table (long period type). Examples thereof include silicon dioxide, aluminum oxide, cerium oxide, titanium oxide, zirconium oxide, silicon nitride, manganese dioxide, silicon carbide, zinc oxide, diamond and magnesium oxide.
Among these, the abrasive particles are preferably colloidal particles. Colloidal particles refer to abrasive particles having a number average particle size of 100 nm or less. Examples of colloidal particles include colloidal silica, colloidal alumina, and colloidal ceria. From the viewpoint of reducing nanoscratches, colloidal silica is preferred. Colloidal silica can be obtained, for example, by a production method in which an aqueous silica solution is used. The dispersion state of these abrasive particles is not particularly limited as long as it has fluidity.
The abrasive particles can be used in combination of two or more. In addition, those obtained by surface modification or surface modification of these particles with functional groups, those obtained by compounding with surfactants or other abrasives, and the like can also be used.

  The average particle diameter of primary particles of abrasive particles such as colloidal particles is 1 to 1 from the viewpoint of reducing nanoscratches and the surface roughness (centerline average roughness: Ra, Peak to Valley value: Rmax). 50 nm is preferred. 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 particles can be determined 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. it can.

  The content of abrasive particles in the container-containing abrasive particle dispersion is preferably 0.5 to 50% by weight, more preferably 0.5 to 25% by weight from the viewpoint of reducing nanoscratches.

  Further, the content of the abrasive particles in the abrasive particle dispersion at the time of use is preferably 0.5% by weight or more, more preferably 1% by weight or more, and further preferably 3% by weight from the viewpoint of improving the polishing rate. % Or more, more preferably 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, still more preferably 13% by weight or less, Preferably it is 10 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 particles may be either the content at the time of manufacturing the abrasive particle dispersion or the content at the time of use. Usually, it is manufactured as a concentrated liquid, and this may be used after being diluted. Many.

  Examples of the medium used for the abrasive particle dispersion of the present invention include water such as ion-exchanged water, distilled water, and ultrapure water, alcohol, and the like. The content of these media corresponds to the balance obtained by removing the abrasive and other components described later from 100% by weight, preferably 60 to 99% by weight, and more preferably 80 to 97% by weight.

  The pH of the container-containing abrasive particle dispersion during storage is preferably away from the isoelectric point of the abrasive particles from the viewpoint of dispersion stability of the abrasive particles and reduction of nanoscratches. The isoelectric point varies depending on the type of abrasive particles. For example, since the isoelectric point of colloidal silica is 1 to 4, the pH during storage is preferably 7 or more, more preferably 8 or more, still more preferably 8.5 or more, still more preferably 9 or more, Further, from the viewpoint of dissolution of colloidal particles, 12 or less is preferable, more preferably 11 or less, and further preferably 10.5 or less.

  The container-containing abrasive particle dispersion of the present invention having such a structure is, for example, mixed with the abrasive particles, water, and, if necessary, other abrasives by a known method, and then put into a container or a container. It can be prepared by adding and mixing the above components therein.

  Examples of the container for storing the abrasive particle dispersion include a back-in box, a can, a drum, and a container.

  From the viewpoint of preventing aggregation due to elution of metal ions, the material of the wall surface in the container is preferably an organic polymer. Further, polyethylene, polypropylene, and poly (tetrafluoroethylene) are particularly preferable from the viewpoint of reducing the adhesion residue of the abrasive particle dispersion.

  In addition, when the abrasive particle dispersion is put in a container, microfiltration with a filter is performed for the purpose of efficiently and economically removing aggregates of abrasive primary particles or coarse abrasive primary particles contained in the dispersion. Preferably used.

Further, the contact angle between the material of the wall surface portion in the container and the abrasive particle dispersion filled in the container as described above is preferably 80 degrees or more, more preferably 85 degrees or more from the viewpoint of reducing nanoscratches. More preferably, it is 90 degrees or more. The contact angle is determined by the material of the wall surface in the container and the surface tension of the dispersion.
The contact angle can be measured by, for example, a contact angle measuring device manufactured by Kyowa Interface Science.

  From the viewpoint of reducing nanoscratches, the container-containing abrasive particle dispersion having the above-described configuration is preferably stored at 0 ° C. or more and less than 60 ° C., more preferably 10 ° C. or more and less than 45 ° C., more preferably It is 20 degreeC or more and less than 35 degreeC.

  The container-containing abrasive particle dispersion of the present invention can be used as a raw material for the polishing composition. In this case, it is preferable to use what adjusted pH of the container-containing abrasive particle dispersion acidic, as an abrasive composition. The pH is specifically 0.1 to 7. In the alkalinity, the generation of nanoscratches is remarkable compared to the 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.

  The pH can be adjusted by the following acid and / or salt thereof. 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 or 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.

  As described above, as an aspect of using the container-containing abrasive particle dispersion liquid of the present invention as a polishing liquid composition, for example, polishing composed of a container-containing abrasive particle dispersion liquid and an acid and / or a salt thereof is used. Liquid kits. Therefore, the present invention also relates to such a polishing liquid kit.

  In the polishing liquid kit, the acid and / or salt thereof may be in a state not mixed with the container-containing abrasive particle dispersion, and is preferably stored in another resistant container before use.

  Moreover, when using a polishing liquid kit, it is preferable to dilute with water just before use, or to add and use an acid and / or its salt from a viewpoint of nano scratch reduction. From the same viewpoint, it is preferable to use up the entire amount in the container once.

  In the polishing liquid kit of the present invention, a polishing liquid composition can be prepared by mixing a container-containing polishing material particle dispersion with an acid and / or a salt thereof. The resulting polishing liquid composition 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, a polishing machine on which the polishing liquid composition is attached to the polishing pad. The substrate is supplied to the sandwiched substrate polishing surface, and is used for the polishing step while contacting the substrate by moving the polishing disk and / or the substrate under a predetermined pressure. This polishing can remarkably suppress the generation of nanoscratches.

  In order to effectively reduce nano scratches, a polishing liquid composition is prepared by using the polishing liquid composition or by mixing each component so as to be a composition of the polishing liquid composition. Grind. Thereby, the surface defect of a to-be-polished substrate, especially nano scratch can be remarkably reduced, and a substrate excellent in surface quality with low surface roughness can be manufactured.

  It is particularly suitable for manufacturing precision component substrates. For example, it is suitable for polishing precision component substrates such as magnetic disk substrates 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, a polishing liquid composition 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. Can be used.

  The material of the object to be polished for which the polishing composition is suitable is, for example, metal or semimetal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, or alloys thereof, glass, glassy carbon, amorphous carbon, etc. Glass materials, alumina, silicon dioxide, silicon nitride, tantalum nitride, titanium carbide and other ceramic materials, polyimide resin and the like. 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.

  The shape of the object to be polished is not particularly limited. For example, the polishing composition is used for 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. It is done. Among them, it is excellent for polishing a disk-shaped workpiece.

  In the substrate manufacturing process, when there are a plurality of polishing processes, it is preferable that the polishing composition of the present invention is used in the second and subsequent processes, which significantly reduces nanoscratches and surface roughness, and has excellent surface smoothness. From the viewpoint of obtaining the above, it is particularly preferred to be 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.

Experimental Examples 1-7
As an abrasive particle dispersion, a colloidal silica dispersion (manufactured by DuPont, average particle diameter of primary particles 22 nm, silica particle concentration 40% by weight) was passed through a precision filter as necessary, and then placed in a container. After appropriately venting air, the mixture was adjusted so as to have a ratio of predetermined liquid contact area / total wall surface area in the container to obtain a colloidal silica dispersion containing the container. After storage at room temperature for 1 month, the colloidal silica dispersion in the container and water are diluted at a ratio of 1: 6 (volume ratio), and sulfuric acid (special grade manufactured by Wako Pure Chemical Industries, Ltd.) is further added to 0.4% by weight. Thus, a polishing composition was prepared (pH 1.5).
Using the polishing composition obtained, the substrate to be polished was polished based on the following method, and the presence or absence of the nanoscratch was evaluated.
In Table 1, the type of container used, presence / absence of precision filter treatment, presence / absence of air bleeding, ratio of wetted area / total wall area in the container, pH of colloidal silica dispersion, container material, contact angle, and The result of a nano scratch is shown.

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 substrates to be polished: 10

2. Substrate to be polished 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 was previously prepared. Using.

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 degrees-Magnification: Maximum (Field range: 1 / 120th 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 into 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.

  From the results shown in Table 1, when the precision filter is used or not used, the ratio of wetted area / total wall surface area in the container is 0.85 or more compared to the smaller one. It can be seen that the occurrence of scratches is remarkably suppressed.

Experimental Examples 8-11
The same colloidal silica dispersion containing the same container as in Experimental Example 1 was stored for 1 month in a thermostatic chamber set to the temperature shown in Table 2, and then polished by the same method as in Experimental Example 1 for nano scratch evaluation. The results are shown in Table 2.

  From the results in Table 2, it can be said that the obtained polishing composition sufficiently retains a practical nanoscratch reduction effect regardless of a wide range of storage temperatures of 5 to 45 ° C.

  The container-containing abrasive particle dispersion of the present invention is used for polishing a disk substrate such as a magnetic disk or a magneto-optical disk or a precision component substrate such as an optical disk, a photomask substrate, an optical lens, an optical mirror, an optical prism, or a semiconductor substrate. It can be suitably used for polishing and the like.

Claims (7)

Ratio of wetted area of abrasive particle dispersion to total area of wall surface in container (wetted area) / (total wall surface area in container)
A container-containing abrasive particle dispersion in which is 0.85 or more.   The container-containing abrasive particle dispersion according to claim 1, wherein the abrasive particles are colloidal particles.   The container-containing abrasive particle dispersion according to claim 1 or 2, wherein the pH is 7 or more.   The container-containing abrasive particle dispersion according to any one of claims 1 to 3, wherein the material of the wall portion in the container is an organic polymer.   The container-containing abrasive particle dispersion according to any one of claims 1 to 4, wherein the contact angle between the material of the wall surface portion in the container and the abrasive particle dispersion filled in the container is 80 degrees or more.   The container-containing abrasive particle dispersion according to any one of claims 1 to 5, which is used together with an acid and / or a salt thereof.   A polishing liquid kit comprising the container-containing abrasive particle dispersion according to claim 1 and an acid and / or a salt thereof.