JP5396047B2 - Abrasive slurry for glass - Google Patents

Description

  The present invention relates to an abrasive slurry for glass comprising abrasive particles having a predetermined particle size distribution.

  In recent years, glass materials have been used for various purposes. In particular, glass substrates for optical disks and magnetic disks, active matrix LCDs (Liquid Crystal Displays), color filters for liquid crystal TVs, clocks, calculators, LCDs for cameras, glass substrates for displays such as solar cells, glass substrates for LSI photomasks, or In a glass substrate such as an optical lens, an optical lens, or the like, a polished surface of the glass is processed with high accuracy.

  In particular, in recent surface polishing of glass, a polishing technique capable of quickly realizing an excellent polished surface without scratches is required. As a solution to such a demand, for example, a polishing liquid as disclosed in Patent Document 1 has been proposed.

  The prior art of Patent Document 1 discloses a CMP polishing liquid characterized in that the abrasive particle size distribution has two or more peaks. According to this prior art, it is possible to realize a polishing liquid having excellent polishing characteristics such as high-speed polishing characteristics, low scratch characteristics, and high planarization performance.

JP 2005-38924 A

  However, since the polishing liquid of Patent Document 1 contains an abrasive having a particle size exceeding 90 nm, it cannot be said to be sufficient for use in a recent glass substrate or the like that requires a highly accurate polished surface. In particular, the polishing surface of glass is not effective for those requiring a polishing accuracy of arithmetic average surface roughness (Ra) of 0.1 nm or less.

  The present invention has been made in the background of the circumstances as described above, and an object thereof is to provide an abrasive slurry for glass capable of processing a polished surface of glass with high accuracy and capable of polishing at a relatively high speed.

  In the present invention, the maximum particle size Tmax of the abrasive particles measured by a transmission electron microscope is 90 nm or less, the maximum particle size Tmax, and the average particle size Tavg of the abrasive particles measured by a transmission electron microscope, Satisfying Tmax / Tavg ≧ 3, and the particle size distribution of the abrasive particles is at least a first peak that appears in the vicinity of the average particle size value and a second peak that appears in the vicinity of a particle size value that is three times or more of Tavg. It is related with the abrasive slurry for glass characterized by having.

  According to the abrasive slurry for glass of the present invention, it is possible to achieve a polishing accuracy of arithmetic average surface roughness (Ra) of 0.1 nm or less in a short time.

  The abrasive slurry for glass of the present invention requires that the maximum particle diameter Tmax of the abrasive particles measured by a transmission electron microscope be 90 nm or less. This is because, with such fine abrasive particles, it is possible to avoid deep polishing scratches on the polished surface of the glass and to realize a highly accurate polished surface.

  The abrasive slurry for glass of the present invention has a maximum particle size Tmax of abrasive particles measured by a transmission electron microscope and an average particle size Tavg of abrasive particles measured by a transmission electron microscope. / Tavg ≧ 3 must be satisfied.

  Furthermore, in the abrasive slurry for glass of the present invention, the particle size distribution of the abrasive particles is at least a first peak that appears in the vicinity of the average particle size value, and a second that appears in the vicinity of a particle size value that is three or more times Tavg. And having a peak. A polishing material exhibiting a particle size distribution having at least such two peaks can realize a high polishing rate.

  The particle size distribution of the abrasive particles in the present invention is determined by the abrasive particles observed with a transmission electron microscope. Specifically, the particle size distribution is determined based on the result of measuring the particle diameter of each particle of 200 or more, preferably 300 to 500, as the number of abrasive particles with a transmission electron microscope. In the present invention, the peak of the particle size distribution refers to a case where the middle section is larger than the frequency (number) of the preceding and following sections in three consecutive sections among the particle diameter sections constituting the particle size distribution.

  In the abrasive slurry for glass according to the present invention, the average particle size is preferably in the range of 5 nm to 20 nm. When the average particle size is less than 5 nm, the polishing rate tends to be low. On the other hand, if the average particle diameter exceeds 20 nm, the arithmetic average surface roughness (Ra) of the polished surface of the glass tends to increase.

  And in the abrasive slurry for glass which concerns on this invention, when an average particle diameter exists in the range of 5 nm-20 nm, a 1st peak appears in the range of 5 nm-20 nm, and a 2nd peak appears in 25 nm-60 nm. Is preferred. If there are two peaks at such positions, the arithmetic average surface roughness (Ra) of the polished surface of the glass is sufficiently low, and the polishing rate is within the range of 5 to 20 nm of the average particle size. More than 5 times larger than abrasives consisting of abrasive particles with only a peak. When the first peak is out of the range of 5 nm to 20 nm, that is, when it is less than 5 nm, the polishing speed tends to be low, and when it exceeds 20 nm, the arithmetic average surface roughness (Ra) of the polished surface of the glass tends to increase. It becomes a trend. Further, when the second peak is out of the range of 25 nm to 60 nm, that is, when it is less than 25 nm, the polishing speed is not improved so much, and when it exceeds 60 nm, the maximum particle size Tmax of the abrasive particles tends to exceed 90 nm, and the polishing scratches. It becomes an abrasive that is easy to generate.

  In the abrasive slurry for glass of the present invention, the abrasive is preferably colloidal ceria, colloidal silica, or a mixture of colloidal ceria and colloidal silica, and colloidal ceria is particularly preferable. This is because if these polishing materials are used for polishing, it becomes easy to make the arithmetic average surface roughness (Ra) of the polished surface of the glass 0.1 nm. In particular, when colloidal ceria is used, it is desirable that the glass after polishing is excellent in cleaning properties and it is difficult for the abrasive particles to remain on the glass surface.

  The abrasive slurry for glass of the present invention can be produced as follows. First, in the case of colloidal silica, spherical particles having a uniform particle diameter are commercially available, and therefore can be produced by mixing two kinds having different particle diameters. That is, for a commercial product with a large particle size (referred to as a large particle size product) and a commercial product with a small particle size (referred to as a small particle size product), the average particle size of the large particle size product / the average particle size of the small particle size product ≧ 3. Colloidal silica used as the abrasive slurry for glass of the present invention can be produced by appropriately mixing two kinds of commercially available products satisfying the relationship of 3 and large particle size average particle size ≦ 90 nm. When the average particle size of the large particle size product / average particle size of the small particle size product is close to 3, unless the amount of use of the small particle size product is increased, the mixture will not satisfy Tmax / Tavg ≧ 3 It becomes. In the case of colloidal silica, since the particle size is relatively uniform, the Tmax of the mixture is only slightly larger than the average particle size of the large particle size product. Therefore, unless two kinds of materials satisfying the relationship of large particle size product average particle size / small particle size product average particle size ≧ 3 are not mixed, it is difficult for the mixture to satisfy Tmax / Tavg ≧ 3.

  And when manufacturing the abrasive slurry for glass of this invention by colloidal ceria, ie, cerium oxide, it can manufacture as follows. The cerium oxide used as the abrasive is a method for producing a cerium-based abrasive comprising cerium oxide by oxidizing cerium (III) hydroxide, and cerium chloride and an alkaline substance are mixed with an inert gas such as nitrogen gas or argon gas. It is preferable to produce by cerium (III) hydroxide by reacting in an atmosphere and oxidizing the cerium hydroxide to obtain cerium oxide. (III) indicates that the valence of cerium is trivalent.

  In this cerium oxide production method, cerium chloride and an alkaline substance are reacted in an inert gas atmosphere. However, the reaction under such conditions is generated because the reaction proceeds rapidly. The particles of cerium hydroxide become fine tetragonal crystals and are oxidized to produce cubic and fine polygonal particles. And the particle size of the cerium oxide particle obtained can be adjusted by controlling reaction of cerium chloride and an alkaline substance.

  Specifically, the reaction for producing cerium (III) hydroxide can be performed by adding cerium chloride and an alkaline substance such as sodium hydroxide to the solvent while maintaining a constant addition rate. By changing the addition rate of cerium oxide, cerium oxide having different particle sizes can be produced. For example, the reaction can be performed by a method in which cerium chloride and an alkaline substance are dropped simultaneously in a solvent, or a method in which cerium chloride and an alkaline substance are brought into contact with each other and then immediately sheared. According to such a method, gelation at the time of reaction is suppressed, and cerium (III) hydroxide) can be generated in a uniform cubic shape. For this reason, the oxidation process easily proceeds uniformly, and fine particles of cerium oxide having a uniform particle diameter can be obtained.

  Further, the reaction between cerium chloride and the alkaline substance is preferably performed at a liquid temperature of 60 ° C. to 104 ° C. and a pH of 5 to 9. When cerium nitrate or cerium ammonium nitrate other than cerium chloride is used as a raw material, the particle diameter tends to increase. If the liquid temperature during the reaction is less than 60 ° C, the viscosity tends to be high and stirring tends to be difficult. Further, when the pH is less than 5, the particle size tends to increase, and when the pH exceeds 9, the particle shape tends to be rod-shaped and the polishing characteristics tend to deteriorate.

  The cerium (III) hydroxide obtained as described above is oxidized with an oxidizing agent to produce cerium oxide. As the oxidizing agent, hydrogen peroxide water, hypochlorous acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, ozone and the like can be used.

  The abrasive slurry for glass of the present invention can be produced by preparing two types of colloidal ceria having different particle sizes by the above production method and mixing them. Colloidal ceria to be mixed is manufactured to have a large particle size (referred to as a large particle size ceria) and a small particle size (referred to as a small particle size ceria product), and those that satisfy the following conditions are mixed. . Preferred conditions are large particle size ceria average particle size / small particle size ceria average particle size ≧ 2, large particle size product average particle size ≦ 70 nm, large particle size ceria average particle size / small particle size ceria average particle size ≧ 3, The condition of large particle size ceria average particle size ≦ 60 nm is more preferable. By mixing under such conditions, the mixture satisfies Tmax / Tavg ≧ 3. In the case of colloidal ceria, since the flow rate distribution has a considerable width, the Tmax of the mixture is considerably larger than the average particle size of the large particle size ceria. Therefore, even if the large particle size ceria average particle size / small particle size ceria average particle size <3, a mixture of two kinds of colloidal ceria having such a relationship often satisfies Tmax / Tavg ≧ 3. .

  According to the present invention, it is possible to polish a polished surface of glass with high accuracy and at high speed.

  The best embodiment of the present invention will be described in detail with reference to examples and comparative examples.

  First, a case where colloidal ceria is used will be described. In the case of colloidal ceria, an abrasive slurry containing two types of cerium oxide with target average particle sizes of 20 nm and 50 nm was produced.

  Colloidal ceria having a target average particle size of 20 nm was produced as follows. First, the cerium chloride aqueous solution was adjusted to 250 g / L in terms of cerium oxide and sodium hydroxide to 174.5 g / L, respectively. Next, 73 L of pure water was added into a 200 L reaction tank, and the mixture was heated to 90 ° C. or higher to perform deaeration treatment. Further, nitrogen gas was introduced at a flow rate of 2.5 L / min and left for 30 minutes to make the inside of the reaction vessel an inert atmosphere.

  Thereafter, both of the cerium chloride aqueous solution and the sodium hydroxide aqueous solution were introduced into the reaction vessel at a flow rate of 260 mL / min and 245 mL / min, respectively, and mixed by vigorous stirring. By this mixing reaction, a purple precipitate was generated in the reaction vessel. The obtained precipitate was identified as cerium (III) hydroxide by X-ray diffraction analysis (XRD).

  In the reaction tank, precipitation begins when an aqueous cerium chloride solution and an aqueous sodium hydroxide solution are introduced into the tank. From this point, a slurry is formed, and stirring in the tank (stirring speed: 250 rpm) is continued to a certain degree of aging treatment. By carrying out, the inside of the tank became a uniform slurry. The cerium (III) hydroxide slurry was aged for 10 minutes at a liquid temperature of 90 ° C. or higher until the reaction was completed. Thereafter, 2400 mL of 12 mass% hydrogen peroxide water was added at a flow rate of 80 mL / min to carry out oxidation treatment.

  After the completion of the oxidation treatment reaction, the resulting slurry was collected and subjected to desalting treatment with a cross-flow filter until the Na ions in the slurry were <10 ppm and the Cl ions were <100 ppm. When solid content in the obtained slurry was analyzed by X-ray diffraction (XRD), it was identified as cerium (IV) oxide.

  Further, colloidal ceria having a target average particle size of 50 nm is the same as the above-described method for producing colloidal ceria having a target average particle size of 20 nm, and the difference is in the mixing of a cerium chloride aqueous solution and a sodium hydroxide aqueous solution in a reaction vessel. is there. In the case of colloidal ceria with a target average particle size of 50 nm, mixing in the reaction tank is only by introducing both of the cerium chloride aqueous solution into the reaction tank at a flow rate of 200 mL / min and a sodium hydroxide aqueous solution at 190 mL / min. Mixed and not vigorously stirred. By this mixing reaction, a purple precipitate was generated in the reaction vessel. The obtained precipitate was identified as cerium (III) hydroxide by X-ray diffraction analysis (XRD).

  In the reaction tank, precipitation begins when an aqueous cerium chloride solution and an aqueous sodium hydroxide solution are introduced into the tank. From this point, a slurry is formed, and stirring in the tank (stirring speed: 250 rpm) is continued to a certain degree of aging treatment. By carrying out, the inside of the tank became a uniform slurry. The cerium (III) hydroxide slurry was aged for 10 minutes at a liquid temperature of 90 ° C. or higher until the reaction was completed. Thereafter, 2400 mL of 12 mass% hydrogen peroxide water was added at a flow rate of 80 mL / min to carry out oxidation treatment.

  After the completion of the oxidation treatment reaction, the resulting slurry was collected and subjected to desalting treatment with a cross-flow filter until the Na ions in the slurry were <10 ppm and the Cl ions were <100 ppm. When solid content in the obtained slurry was analyzed by X-ray diffraction (XRD), it was identified as cerium (IV) oxide.

  The colloidal ceria having a target average particle size of 20 nm obtained as described above was weighed in a 2 L beaker so as to be 57 g in terms of solid content, and 143 g of colloidal ceria having a target average particle size of 50 nm was measured in terms of solid content, Further charged into a 2L beaker. Then, an abrasive slurry (Example 1) made of colloidal ceria was prepared by adding pure water to a 2 L beaker and adjusting the solid content concentration to 10% by weight so that the content was 2000 g. Polishing evaluation of quartz was performed using this polishing material slurry. Polishing evaluation was performed by examining the polishing speed and the surface roughness of the surface to be polished.

The polishing test was performed using a single-side polishing machine (manufactured by MT Corporation). As the polishing conditions, quartz glass (diameter 60 mm) was polished as an object to be polished using a polyurethane polishing pad. Then, the abrasive slurry was supplied at a rate of 25 mL / min, the pressure on the polishing surface was set to 9.0 kPa (0.088 kg / cm ² ), and polishing was performed at a polishing machine rotation speed of 60 rpm for 30 minutes. A polishing process was performed for 30 minutes, and the glass mass before and after the polishing was measured to determine the amount of reduction of the glass mass due to the polishing. Based on this value, the polishing rate was determined. Regarding the polishing accuracy, the polished surface of the glass obtained by polishing was washed with pure water, dried in a dust-free state, and the polishing accuracy was evaluated. The surface roughness is measured with an atomic force microscope (AFM; Nanoscope IIIA manufactured by Biko Japan) in a measurement range of 10 μm × 10 μm on the polished surface of the glass after polishing. The thickness Ra was calculated.

  In the abrasive slurry of Example 1, the polishing rate was 0.113 μm / min, and the arithmetic average surface roughness (Ra) of the polished surface was 0.070 nm.

Comparative Example 1: For comparison, an abrasive slurry using only the colloidal ceria having the target average particle diameter of 20 nm was prepared. The colloidal ceria having a target average particle diameter of 20 nm used in Example 2 above was weighed into a 2 L beaker so as to be 200 g in terms of solid content, and pure water was added so that the content became 2000 g. Thus, the abrasive slurry by the target average particle diameter of 20 nm colloidal ceria which solid content concentration was adjusted to 10 weight% was produced. Polishing evaluation of quartz was performed using this polishing material slurry. The polishing evaluation method is the same as in Example 1.

  As a result, the polishing slurry of Comparative Example 1 had a polishing rate of 0.004 μm / min and an arithmetic average surface roughness (Ra) of the polished surface of 0.067 nm.

Comparative Example 2: For comparison, an abrasive slurry using only the colloidal ceria having the target average particle diameter of 50 nm was prepared. Colloidal silica with a target average particle size of 50 nm was weighed into a 2 L beaker so that the solid content was 200 g, and pure water was added to make the content 2000 g. In this way, an abrasive slurry with a particle size of about 50 nm colloidal ceria having a solid content concentration adjusted to 10% by weight was prepared. Polishing evaluation of quartz was performed using this polishing material slurry. The polishing evaluation method is the same as in Example 1.

  As a result, in the abrasive slurry of Comparative Example 2, the polishing rate was 0.225 μm / min, and the arithmetic average surface roughness (Ra) of the polished surface was 0.158 nm.

  Next, the case where colloidal silica is used will be described. Colloidal silica having an average particle size of about 20 nm (trade name “COMPOL 20” manufactured by Fujimi Incorporated) was weighed into a 2 L beaker so that the solid content was 57 g. Then, 143 g of colloidal silica having an average particle size of about 80 nm (trade name “COMPOL 80”: manufactured by Fujimi Incorporated Co., Ltd.) in terms of solid content was weighed and put into a 2 L beaker.

  Pure water was added to a 2 L beaker charged with two types of colloidal silica to adjust the content to 2000 g and the solid content concentration to 10% by weight to prepare an abrasive slurry with colloidal silica. Polishing evaluation of quartz was performed using this polishing material slurry. The polishing evaluation was the same as in Example 1 above.

  In the abrasive slurry of Example 2, the polishing rate was 0.050 μm / min, and the arithmetic average surface roughness (Ra) of the polished surface was 0.081 nm.

Comparative Example 3: For comparison, an abrasive slurry using only the colloidal silica having a particle diameter of about 20 nm was prepared. The colloidal silica having a particle diameter of about 20 nm used in Example 1 above was weighed into a 2 L beaker so that the solid content was 200 g, and pure water was added so that the content became 2000 g. Thus, an abrasive slurry with a particle size of about 20 nm colloidal silica having a solid content adjusted to 10% by weight was prepared. Polishing evaluation of quartz was performed using this polishing material slurry. The polishing evaluation method is the same as in Example 1.

  As a result, the polishing slurry of Comparative Example 3 had a polishing rate of 0.002 μm / min and an arithmetic average surface roughness (Ra) of the polished surface of 0.067 nm.

Comparative Example 4: For comparison, an abrasive slurry using only the colloidal silica having a particle diameter of about 80 nm was prepared. In Comparative Example 2, an abrasive slurry was prepared under the same conditions as in Comparative Example 1 except that colloidal silica having a particle size of about 80 nm used in Example 1 was used. Then, this polishing material slurry was used to evaluate the polishing of quartz. The polishing evaluation method is the same as in Example 1.

  As a result, the polishing slurry of Comparative Example 4 had a polishing rate of 0.014 μm / min and an arithmetic average surface roughness (Ra) of the polished surface of 0.233 nm.

  Then, the result of having investigated the particle size distribution about each Example and a comparative example is demonstrated.

  Tables 1 to 6 show the results of examining the particle size distribution of the abrasive particles for each example and comparative example. This particle size distribution was created as follows.

  The particle diameter (TEM diameter) obtained by a transmission electron microscope was specified as follows. First, a TEM image was taken with a transmission electron microscope at a magnification at which 200 to 1000 particles were included in one field of view. Then, tracing paper or an OHP sheet is placed on the TEM image photograph, and the outlines of all the particles are traced. FIGS. 1 and 2 show a TEM image photograph and a trace drawing thereof in the case of Example 1, FIGS. 3 and 4 show the case of Comparative Example 1, and FIGS. 5 and 6 show the case of Comparative Example 2. FIG. ing. The trace drawing obtained in this way is read by a scanner (flat head scanner CanonScan 8200F: output resolution 400 dpi), converted into electronic data, and image data (Image Pro Plus: Media Cybernetics, Inc.) is used to scan the object (individual particles). ) By measuring the diameter passing through the center of gravity in increments of 2 °, taking the average value as the particle size of the particle, measuring the particle size of all the electronic data particles, and dividing the total by the number of particles. The average particle size Tavg was specified. Further, from the particle size values of the individual particles, the number of particles was counted with respect to the particle size sections described in Tables 1 to 6 below, thereby creating a particle size distribution table.

  Since the maximum particle size of the abrasive particles in the present example is 90 nm, the data size interval was set between 0 and 100 nm at intervals of 5 nm. Each particle size distribution table is shown below.

  From Tables 1 to 3 and the results of polishing evaluation thereof, in the case of colloidal ceria, there are two peaks in the particle size distribution as in Example 1, and the maximum particle size Tmax and the average particle size Tavg are Tmax / Tavg. In the case of satisfying ≧ 3, it was found that the surface roughness of the polished surface was the same level as that of Comparative Example 1, but the polishing speed was nearly 30 times faster. Further, it was found that the surface roughness of the surface to be polished was significantly reduced, although the polishing rate was slightly slower when compared with Comparative Example 2.

  From the results of Tables 4 to 6 and the polishing evaluation thereof, in the case of colloidal silica, there are two peaks in the particle size distribution as in Example 2, and the maximum particle size Tmax and the average particle size Tavg are Tmax / Tavg. For those satisfying ≧ 3, it was found that the surface roughness of the polished surface was the same level as that of Comparative Example 3, but the polishing speed was nearly 25 times faster. Further, when compared with Comparative Example 4, it was found that the polishing speed was increased by a factor of 3 and the surface roughness of the polished surface was significantly reduced.

4 is a TEM image of Example 1. FIG. 2 is a trace drawing of Example 1. FIG. 4 is a TEM image of Comparative Example 1. Trace drawing of comparative example 1 TEM image of Comparative Example 2. The trace drawing of the comparative example 2. FIG.

Claims (2)

The maximum particle size Tmax of the abrasive particles measured by a transmission electron microscope is 90 nm or less,
The maximum particle size Tmax and the average particle size Tavg of the abrasive particles measured by a transmission electron microscope satisfy Tmax / Tavg ≧ 3,
The particle size distribution of該研friction material particles, at least, possess a second peak appeared in the vicinity of the first peak and 3 times more particle size value of Tavg appeared in the vicinity of the average particle size value,
An abrasive slurry for glass, wherein the first peak appears in the range of 5 nm to 20 nm, the second peak appears in the range of 25 nm to 60 nm, and the abrasive is colloidal ceria . The abrasive slurry for glass according to claim 1, wherein the average particle diameter is in the range of 5 nm to 20 nm.