KR100697304B1 - Sheet-Shaped Kaolin and Cerium Oxide Complex Abrasive Material and Method for Manufacturing the same - Google Patents

Abstract

Provided are a plate kaolin-ceria composite abrasive which is excellent in polishing velocity and polishing performance and is minimized in the precipitation due to the agglomeration of ceria particles, and a method for preparing the plate kaolin-ceria composite abrasive. The plate kaolin-ceria composite abrasive comprises 5-2,000 parts by weight of a plate kaolin having a major axis length of 5 micrometers or less; and 100 parts by weight of a ceria particle having a diameter of 1 micrometer or less which is mixed or ball-milled on the outer surface of the plate kaolin. Preferably the ceria is a ceria granule having a diameter of 1 micrometer or less prepared in the preparation process of a ceria abrasive or a rare earth element compound containing ceria.

Description

Sheet-Shaped Kaolin and Cerium Oxide Complex Abrasive Material and Method for Manufacturing the same}

1a and 1b are SEM images of the plate-shaped kaolin according to the present invention,

2a and 2b are SEM images of the plate-shaped kaolin particles used as a comparative example in the present invention,

3A and 3B are SEM images of ceria used as an example in the present invention,

4a, 4b, 4c and 4d are SEM images of the composite slurry particles produced by mixing or ball milling the mixed slurry of ceria and plate kaolin according to the present invention,

5 is a graph of weight loss vs. polishing time of an example according to the present invention and a comparative example compared with the present invention;

6 is a graph showing the polishing rate versus the polishing time of the example according to the present invention and the comparative example compared with the present invention.

The present invention relates to a plate-like kaolin-ceria composite polishing material and a method of manufacturing the same, and more particularly, to mixing a plate-like kaolin having a long axis length of 5 μm or less and a rare earth compound containing ceria or ceria having a diameter of 1 μm or less at room temperature, or mixing them. It relates to a method for producing a plate-shaped kaolin-ceria composite abrasive material by coating a ceria on the outer surface of the plate-shaped kaolin by ball milling and plate-shaped kaolin-ceria composite abrasive material through the same.

Today, with the development of semiconductor and electronic technology, the importance of wide-area leveling of wafers of semiconductor devices and the polishing of surfaces of glass and optical lenses used in electrical and electronic products is greatly increased. Among these, chemical mechanical polishing (CMP) has begun to attract attention as a new planarization technique.

Polishing slurry used in semiconductor and glass polishing process is composed of metal oxide, deionized water, additives, etc., and metal oxides include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO ₂ ), and zirconia (ZrO). ₂ ) etc. are mainly used.

Cerium-based abrasives have been used mainly for conventional optical lens polishing. Recently, this abrasive has been widely used as an abrasive for glass materials used in electrical and electronic equipment. The cerium-based abrasive is prepared from cerium rare earth carbonate obtained from bastnasite ore or composite ore produced in China, or a rare earth carbonate is fired at high temperature to produce cerium rare earth oxide.

Abrasives are important for particle size, distribution, grain surface roughness, and scratches are very important for optical and precision glass polishing. To this end, there are removal of alkali metals for preventing agglomeration of particles, addition of a fluorination process for flatness of the polished surface, and a grinding process by ball milling.

US Patent No. 6,905,527, "Method of Manufacturing Cerium Abrasives," discloses a method of preparing cerium abrasives prepared by adding fluorine compounds and dispersants to powders obtained through grinding, firing, and wet regrinding of cerium abrasives. Aqueous dispersion, method and use for the preparation of U. S. Patent Publication No. 95873 discloses silica abrasives having no average particle diameter of less than 100 nm (without microscratches and high polishing rates). 6,328,944, 'Coated pyrogenic oxides', discloses pyrogenic oxides applied to metals and nonmetals with metals, nonmetals or their oxides and salts. However, these slurries also had problems of low uniformity of particle size.

The slurry using ceria as abrasive particles is 3 ~ 4 times faster than silica type, and shows high removal rate in neutral, but it is expensive, and it is large from the polygonal shape and uneven particle size of existing ceria particles. Due to the presence of particles and aggregated particles During the polishing process, scratches occur on the glass surface and the flatness in the glass surface is reduced. In addition, Ceria has a value of 27.7, which is a measure of the mutual pull force between particles, which is much higher than that of silica (5.99) or alumina (15.4). There is a high possibility of precipitation due to spontaneous reaggregation because there is little force to maintain the. During polishing, the glass surface may become larger in size due to aggregation of particles such as silica or ceria contained in the slurry, or process abnormalities such as scratches may occur due to particles caused by polishing by-products generated during polishing, which is reliable in glass polishing. Causes problems to drop.

 In addition, in the `` dry blasting abrasive '' of JP-A-2000-0055239, surface treatment of a material that imparts water repellency to spherical inorganic particles and effectively prevents troubles such as agglomeration of the abrasive due to moisture, solidification, and adhesion to an abrasive. Disclosed is an abrasive to prevent. The content disclosed in Japanese Patent Application Laid-Open No. 2000-0055239 is to surface-treat a material that imparts water repellency to spherical inorganic particles. As spherical inorganic particles, glass beads, alundum, corundum, cellarized beads, stainless steel, copper, etc. are used. In addition, the fluidity improving agent of the average particle diameter of 1/10 or less of the average particle diameter of a spherical inorganic particle is added and mixed, and kaolin is used as one of the fluidity improving agents.

In 'Abrasives based on mullite and its manufacturing method' of Korean Patent Laid-Open Publication No. 1999-0075271, the mullite is calcined by mixing and pulverizing kaolin and Al ₂ O ₃ powder by compression molding and calcining by heat treatment at a temperature of 1250 ° C. or higher. It was disclosed for the production method of the abrasive which is obtained by firing at a temperature of 1450 ℃ ~ 1600 ℃ mixed ZrO ₂ and firing at a temperature of 1450 ℃ to 1550 ℃. The contents disclosed in Japanese Patent Laid-Open No. 1999-0075271 provide abrasives based on mullite having excellent mechanical properties by transferring zircon at high temperatures.

The present invention is to overcome the above-mentioned problems of the prior art, by mixing or ball milling the plate-shaped kaolin and fine grain ceria particles, providing a plate-like kaolin-ceria composite abrasive material combining fine ceria particles on the outer surface of the plate-shaped kaolin and polishing method thereof The purpose is to minimize the sedimentation phenomenon due to aggregation between ceria particles while using ceria having good speed and polishing performance as abrasive particles. In addition, an object of the present invention is to improve the flatness in the glass surface or between the glass plate through the plate-shaped kaolin-ceria composite abrasive, and to have a low defect rate after polishing. In addition, an object of the present invention is to mass-produce plate-like kaolin-ceria composite abrasives for CRT glass and ultra-precision glass using a manufacturing process using a low-cost plate-shaped kaolin raw material.

The above object can be achieved through a plate-like kaolin-ceria composite abrasive material in which a rare earth compound containing ceria or ceria having a diameter of 1 μm or less is mixed or ball milled on an outer surface of a plate-shaped kaolin having a long axis length of 5 μm or less. In addition, the step of mixing a mixture slurry of 5 μm or less plate kaolin and 1 μm or less diameter ceria mixed at 15 ℃ to 70 ℃ for 10 minutes to 2 hours; Or ball milling the mixed slurry can be achieved through the method of producing a plate-like kaolin-ceria composite polishing material using a ball milling step to more effectively coat the ceria on the outer surface of the plate-shaped kaolin.

The plate-shaped kaolin-ceria composite abrasive according to the present invention and the weight ratio of ceria and plate-shaped kaolin used in the preparation method are 5 parts by weight to 2,000 parts by weight based on 100 parts by weight of the rare earth compound containing ceria or ceria. More preferably, it is 5 weight part-200 weight part, Most preferably, it is 5 weight part-50 weight part.

In addition, the plate-shaped kaolin-ceria composite abrasive according to the present invention and ceria used in the preparation method include a high purity ceria or a rare earth compound containing ceria.

Hereinafter, the technical configuration of the present invention will be described in detail.

The plate-like kaolin-ceria composite abrasive according to the present invention is formed by mixing plate-shaped kaolin (Sheet-Shaped Kaolin) and ceria (CeO ₂ ) or by ball milling after mixing.

The present invention is characterized by using a kaolin (Kaolin) having a plate-like structure.

Kaolin is a purple clay produced in the high lands of Jiangsu province in China and is the name of the ore attached to the ore used to make pottery. Kaolinite is a purple hydrous silicate mineral that is the main constituent of kaolin. The mineral constituting kaolin is Al ₂ Si ₂ O ₅ (OH) ₄ or Al ₂ O ₃ 2SiO ₂ 2H ₂ O, and in addition to kaolinite, halloysite (halloysite, Al ₂ O ₃ SiO ₂ 4H ₂ O), There are nacrite and dickite, but kaolinite and halosite are the main minerals. Kaolin contains impurities such as mica, quartz, feldspar, smectite, iron oxide minerals, titanium oxide minerals and manganese oxide minerals.

The kaolin minerals are all Al ₂ Si ₂ O ₅ (OH) _4, but have different crystal structures. The crystal structure of kaolinite, one of the main constituent minerals, is composed of one [Si ₄ O ₁₀ ] tetrahedral layer and one [Al ₄ O ₄ (OH) ₄ ] octahedral layer. In the present invention, kaolinite, which is a crystal structure in which kaolin forms a plate, is used.

The shape and size of the particles is the most important factor in determining the properties of kaolin. This is because these two influence the deformation of a mixture of clay and water. In addition, the incorporation of foreign matters greatly affects these properties. These impurities are the biggest detrimental to the quality of kaolin, because the presence of other clay minerals in kaolin, or iron in the kaolin mineral lattice or as an entity, lowers the kaolin's ore and product brightness.

The kaolin used in the present invention can be used not only using natural kaolin, but also synthetic kaolin as long as it exhibits the same effect.

It is preferable to use plate-shaped kaolin whose long axis length is 5 micrometers or less, More preferably, kaolin whose long axis length is 2 micrometers or less is used. If the long axis length of the plate-shaped kaolin is larger than 5 μm, several plate-shaped kaolins in contact with the glass substrate may be stacked and may not be brought into flat contact with the glass substrate, and the polishing rate may be unevenly transmitted to the ceria particles coated on the plate-shaped kaolin, resulting in a polishing rate. This reduced disadvantage may occur.

Moreover, as ceria, it is preferable to use the ceria of 1 micrometer or less in diameter, More preferably, the ceria of 500 nm or less is used. If the diameter of the ceria is larger than 1㎛, a problem occurs due to scratching during polishing, and in the plate kaolin-ceria composite abrasive material in which the plate kaolin and ceria are mixed or ball milled, the relative particle number of the ceria is not high so that the polishing efficiency is reduced or coated. There is a disadvantage that the bonding force is lowered. The ceria used in the present invention may use a rare earth compound containing ceria in addition to the general ceria, and further, may be used by mixing only the rare earth compound.

In the present invention, rare earth compounds used with ceria may be classified as light rare earth, medium rare earth, and heavy rare earth, and any rare earth having a desired effect in the present invention may be limited. Do not.

Rare earth compounds that can be used in the present invention are candium (scandium), yttrium (lanthanum), lanthanum (certhanum), cerium (cerium), praseodymium (praseodymium), neodymium (neodymium), promethium (samarium), europium ( At least one of oxides such as europium, gadolinium, terbium, dysprosium, dysprosium, holmium, erbium, thulium, ytterbium, and rutetium It may form or exist in the form of metal or compound.

The weight ratio of plate kaolin and ceria is preferably 5 to 2,000 parts by weight, more preferably 5 to 200 parts by weight, and most preferably 5 parts by weight of plate kaolin, based on 100 parts by weight of ceria. To 50 parts by weight is used.

If the content of plate kaolin is less than 5 parts by weight, ceria that are not bound with plate kaolin aggregate and precipitate together, which may cause scratches on the glass substrate. Also, if the content of ceria is greater than 50 parts by weight, ceria bound to the surface of the plate kaolin is less. The problem that the polishing efficiency is low due to the plate kaolin with a low number of particles and low polishing efficiency occurs.

It looks at the manufacturing method of the plate-shaped kaolin-ceria composite abrasive according to the present invention.

The manufacture of plate-shaped kaolin-ceria composite abrasives is carried out through a mixing step of mixing plate-shaped kaolin and ceria to make a composite slurry, or a ball milling step of ceria bonding to the surface of the plate-shaped kaolin by ball milling the mixed compound slurry. Are manufactured.

In the mixing step, a composite slurry obtained by mixing ceria having a plate-shaped kaolin diameter of 1 μm or less with a long axis length of 5 μm or less is prepared by stirring. In the mixing step, the temperature and time is preferably set to sufficiently mix the plate kaolin and ceria, and may vary depending on the size of the plate kaolin and ceria. It is preferable to advance mixing temperature at 15 degreeC-70 degreeC, More preferably, it is 25 degreeC-50 degreeC. The mixing time is preferably 10 minutes to 2 hours, more preferably 30 minutes to 1 hour 30 minutes.

The ball milling step can be performed once or twice as necessary. In the ball milling step, plate-shaped kaolin and ceria are ground to prepare a composite slurry, and the ball milling time is preferably performed for 0.5 to 5 hours.

In the ball milling step, ceria is bonded to the outer surface of the plate kaolin. Ball milling plate kaolin and ceria particle size is smaller, the plate kaolin-ceria composite abrasive material through the ball milling step is higher than the plate kaolin-ceria composite abrasive material made only by the mixing step, and scratch generation can be minimized. . Whether to use the plate-like kaolin-ceria composite abrasive through the mixing step or the plate-based kaolin-ceria composite abrasive through the ball milling step may be selected according to the use of the abrasive and the type of the target glass substrate. The physical and chemical properties of ceria and plate kaolin used in the production method are as described above.

In the present invention, while using a ceria-based abrasive having a higher polishing efficiency than that of a silica-based abrasive or an alumina-based abrasive, a relatively inexpensive plate-like kaolin is used to prevent ceria particles from agglomerating and settling due to strong mutual stresses between ceria particles. Use composite abrasives with ceria particles mixed or ball milled.

In addition, the polishing properties may be improved by mixing or ball milling a rare earth compound containing ceria as a ceria-based abrasive with plate-shaped kaolin.

Hereinafter, the plate-shaped kaolin-ceria composite abrasive and the manufacturing method according to the present invention will be described in detail through specific experimental data and examples.

Table 1 and Table 2 below show the mixing ratios (% by weight) of the Examples and Comparative Examples.

division Sample Name Plate kaolin (%) Ceria (%) Alumina (%) Example 1 BKC 5 5 95 - Example 2 BKC 10 10 90 - Example 3 BKC 15 15 85 - Example 4 BKC 20 20 80 - Example 5 BKC 30 30 70 - Example 6 MKC 5 50 50 - Example 7 MKC 15 60 40 - Example 8 MKC 30 70 30 - Comparative Example 1 Al ₂ O ₃ - - 100 Comparative Example 2 Rare Earth Compounds with CeO ₂ - 100 -

division Sample Name kaoline(%) Ceria (%) Kaolin Types Example 3 BKC 15 15 85 Plate Comparative Example 3 BK1C 15 15 85 Plate + Bed Comparative Example 4 BK2C 15 15 85 Plate + SiO ₂ (Quartz)

The experimental conditions (Process Conditions of CMP Equipment) polished using the abrasives corresponding to the Examples and Comparative Examples of Table 1 and Table 2 are shown in Table 3.

Polishing machine Condition Head Speed (rpm) fixed Table Speed (rpm) 400 Down force (N) 200 Slurry Flow Rate (Ml / min) 75 Slurry (6wt%) Total Slurry Amount 2L Slurry Ball-milling (rpm) at 250 rpm for 2hr slurry bath stirrer Speed (rpm) 250 Polished Wafer (1.1mm thickness) Soda-lime glass -

As shown in Table 3, in the present invention, using a PHOENIX ALPHA / BETA + VECTOR Grinder Polisher (Buehler) polisher attached with a φ10 ", MH C14B (Rohm & Haas) Grooved Pad, a φ4", soda-lime glass wafer was used. Polishing work. The head was fixed and the table rotation speed was 400rpm. The slurry was charged at 75 ml / min. The film thickness before and after polishing was measured using an Ellipsometer (Auto EL-II, Rudolph), and the removal rate (RR, removal rate) was measured using a scale (measurement accuracy: ± 0.0001g) before and after weight change. Measured and calculated.

1A and 1B are SEM images of the plate-shaped kaolin according to the present invention. As shown in FIGS. 1A and 1B, kaolin has a plate shape and varies in size from several tens of micrometers to several micrometers. In the example experiment according to the present invention, the size of the plate-shaped kaolin was used less than 5㎛, the main component is a kaolinite structure. FIG. 1A is an SEM photograph of 10,000 × magnification of plate kaolin, and FIG. 1B is an SEM photograph of 2,0000 × magnification of plate kaolin.

As shown in FIGS. 1A and 1B, ceria particles may be bonded to the front and rear surfaces of the plate using the structural characteristics of the plate-shaped kaolin.

2a and 2b are SEM images of the plate-shaped kaolin used as a comparative example in the present invention. Figure 2a is a SEM picture of kaolin in the form of a mixture of plate-shaped kaoliite and needle-shaped halosite. FIG. 2B is a SEM photograph of kaolin in the form of plate-shaped kaolinite and quartz.

3A and 3B are SEM images of ceria used as an example in the present invention. The size of ceria used as an example in the present invention was smaller than 1㎛. FIG. 3A is an SEM image of 10,000 times magnification of Ceria, and FIG. 3B is an SEM image of 2,0000 times magnification of Ceria.

4A, 4B, 4C, and 4D are SEM images of a composite slurry in which ceria and plate kaolin are mixed and ball milled according to the present invention, and are distinguished according to the content ratio of ceria and plate kaolin.

4A is a SEM photograph of 10,000-fold magnification of a plate-shaped kaolin-seria composite slurry ball milled with a plate-shaped kaolin and ceria in a 5:95 ratio (weight ratio). 4B and 4C are SEM images of 10,000-fold magnification of the plate-shaped kaolin-ceria composite slurry in which plate-shaped kaolin and ceria were mixed and ball milled at a ratio of 15:85 (weight ratio), respectively. FIG. 4D is a SEM photograph of 10,000-fold magnification of a plate-shaped kaolin-ceria composite slurry ball-milled with a plate-shaped kaolin and ceria in a 30:70 ratio (weight ratio). In FIG. 4B, the uniform mixing of the plate-shaped kaolin and ceria is not easy and the size of the agglomerated particles is relatively larger than that of the polishing slurry produced by the ball milling process. In FIGS. 4A, 4C and 4D, the plate-kaolin and ceria particles are It can be seen that the ball milling is closely adhered to the uniform mixing and the plate-like kaolin outer surface. The plate kaolin to which ceria particles are bound prevents mutual stress between ceria particles and prevents precipitation with aggregation of ceria and stability of complex sludge.

5 is a graph of weight loss vs. polishing time of an example according to the present invention and a comparative example compared with the present invention. Referring to Figure 5 Example 1 to Example 5 (BKC 5 ~ 30) using the plate-shaped kaolin-ceria composite abrasive prepared by ball milling plate-shaped kaolin-ceria composite abrasive material of Example 6 to Example 8 (MKC 5-30) and alumina (Al ₂ O ₃ 100%) or ceria (CeO ₂ 100%) compared with Comparative Example 1 and Comparative Example 2 using only the same time than the weight loss of the glass substrate can be seen that much. In particular, when the weight ratio of kaolin / ceria in the composite abrasive material is about 5% to 30% by weight, the weight loss is high and the polishing properties (scratch, roughness, flatness, etc.) are improved, which is due to the effective binding of ceria to plate kaolin. This is because more ceria particles may contact the glass substrate on the outer surface of the plate kaolin. When an excess of plate-like kaolin is added, it may be a problem due to low polishing power of kaolin.

6 is a composite abrasive material ball milled with Example 3 (BKC 15, kaolinite: ceria = 15: 85) and kaolin and ceria containing a needle-like halosite compared to the present invention (Comparative Example 3) , BK1C 15) and kaolin and ceria containing plate-shaped kaolinite and quartz ball milled composite abrasives (Comparative Example 4, BK2C 15). Looking at Figure 5 it can be seen that the polishing rate (nm / min) is improved when using the kaolin containing pure plate kaolinite than the kaolin containing a needle-like halosite or quartz in the plate kaolinite.

In the above, this invention was demonstrated in detail with reference to an Example and a comparative example centering on a structure. However, the scope of the present invention is not limited to the above embodiments but may be embodied in various forms of embodiments within the appended claims. Without departing from the gist of the invention as claimed in the claims, any person of ordinary skill in the art is deemed to be within the scope of the claims underlying the present invention to the extent possible for various modifications.

In addition, the preferred range, more preferred range, and even more preferred range limitation in the present invention is to maximize the effect even more, it is possible to obtain a more satisfactory technical effect by narrowing the limited range.

Based on the technical configuration described above, the present invention has the effect of improving the flatness in the glass surface or between the glass plates and preventing a precipitation phenomenon due to the aggregation between fine grain ceria particles and having a low defect rate after polishing. In addition, the present invention can mass-produce plate-like kaolin-ceria composite abrasives for CRT glass and ultra-precision glass using a manufacturing process using an inexpensive plate-like kaolin raw material.

Claims (6)

A plate-shaped kaolin-ceria composite abrasive material formed by mixing or ball milling a ceria having a diameter of 1 μm or less on an outer surface of a plate-shaped kaolin having a long axis length of 5 μm or less. The method of claim 1, The plate-like kaolin is a plate-shaped kaolin-ceria composite abrasive, characterized in that from 5 parts by weight to 2,000 parts by weight based on 100 parts by weight of ceria. The method of claim 1, The ceria is a plate-shaped kaolin-ceria composite abrasive, characterized in that using a rare earth compound containing fine ceria or ceria of 1 ㎛ or less prepared in the ceria abrasive manufacturing process. The method of claim 3, The rare earth compound is scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium (gadolinium), terbium (terbium), dysprosium (dysprosium), holmium (holmium), erbium (erbium), thallium, ytterbium (ytterbium), characterized in that at least one of the lutetium (lutetium) Ceria composite abrasive. A plate-shaped kaolin comprising a mixing step of stirring and mixing a composite slurry of a plate-shaped kaolin having a long axis length of 5 μm or less and a ceria or ceria having a diameter of 1 μm or less at 15 ° C. to 70 ° C. for 10 minutes to 2 hours. -Ceria composite abrasive material manufacturing method. The method of claim 5, Method for producing a plate-shaped kaolin-ceria composite abrasive material, characterized in that the ball milling step of milling the composite slurry for 0.5 to 5 hours to crush the plate kaolin and ceria or the rare earth compound once or twice.

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