TWI404598B - Glass slurry - Google Patents

Abstract

Disclosed is a glass polishing material slurry which enables high-precision processing of a glass surface to be polished, while enabling polishing at relatively high rate. The glass polishing material slurry is characterized in that the maximum particle diameter Tmax of polishing material particles as measured by a transmission electron microscope is not more than 90 nm, the maximum particle diameter Tmax and the average particle diameter Tavg of polishing material particles as measured by a transmission electron microscope satisfy the following relation: Tmax/Tavg = 3, and the particle size distribution of the polishing material particles has at least a first peak appearing near the average particle diameter and a second peak appearing near the particle diameter of three or more times the Tavg.

Description

Glass slurry

The present invention relates to a slurry for glass composed of particles of abrasive materials having a predetermined particle size distribution.

In recent years, glass materials have been used for various purposes. In particular, glass substrates for optical disks or disks, active matrix LCDs, liquid crystal filters, clocks, computers, LCDs for cameras, solar cells, and other glass substrates for displays, LSI (Large) -Scale Integration; Large-scale integrated circuit) A glass substrate such as a photomask glass substrate or an optical lens, and an optical lens, etc., are processed with high precision on the polished surface of the glass.

In particular, in the surface grinding of glass, a grinding technique capable of quickly achieving a flawless good grinding surface is required. In response to such a demand, a polishing liquid such as Patent Document 1 has been proposed.

In the prior art of Patent Document 1, a polishing liquid for CMP (Chemical Mechanical Polishing) having a particle size distribution of an abrasive material having two or more peaks has been disclosed. According to this prior art, it is possible to realize a polishing liquid having excellent polishing characteristics such as high-speed polishing characteristics, low enthalpy characteristics, and high flattening characteristics.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-38924

However, since the polishing liquid of Patent Document 1 contains an abrasive having a particle diameter of more than 90 nm, it is difficult to use a glass substrate or the like which is required to have a polishing surface of high precision recently. In particular, it is not an effective technique for the polishing precision of the polished surface of the glass to have an arithmetic mean surface roughness (Ra) of 0.1 nm or less.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a polishing slurry for glass which can be processed at a high speed and which can be polished at a high speed.

The present invention relates to a polishing slurry for glass characterized in that the maximum particle diameter Tmax of the abrasive particles measured by a transmission electron microscope is 90 nm or less, and the maximum particle diameter Tmax is measured by a transmission electron microscope. The average particle diameter Tavg of the abrasive particles satisfies Tmax/Tavg ≧3, and the particle size distribution of the abrasive particles has at least a first peak appearing near the average particle diameter value and a particle diameter value appearing more than three times the Tavg. Two peaks.

According to the polishing slurry for glass of the present invention, the polishing precision with an arithmetic mean surface roughness (Ra) of 0.1 nm or less can be achieved in a short time.

The maximum particle diameter Tmax of the abrasive particles measured by the transmission electron microscope of the polishing slurry for glass of the present invention is preferably 90 nm or less. As long as such fine abrasive particles are used, it is possible to avoid deep scratches on the polished surface of the glass, and it is possible to realize a polishing surface of higher precision.

Further, in the polishing slurry for glass of the present invention, the maximum particle diameter Tmax of the abrasive particles measured by a transmission electron microscope and the average particle diameter Tavg of the abrasive particles measured by a transmission electron microscope are required to satisfy Tmax/Tavg. ≧ 3.

Further, the polishing slurry for glass of the present invention is characterized in that the particle size distribution of the abrasive particles has at least a first peak appearing in the vicinity of the average particle diameter and a second peak appearing in the vicinity of the particle diameter three times or more of Tavg. When an abrasive material having a particle size distribution of at least these two peaks is displayed, a high-speed polishing speed can be achieved.

The particle size distribution of the abrasive particles in the present invention is determined based on the particles of the abrasive material observed by a transmission electron microscope. Specifically, the number of abrasive particles measured by a transmission electron microscope is 200 or more, and it is preferable to measure the particle diameters of 300 to 500 particles, and the particle size distribution is determined based on the measurement results. In addition, in the section of the particle diameter of the particle size distribution, the peak of the particle size distribution in the present invention is a case where the interval in the center is larger than the frequency (number) in the preceding and succeeding sections in the three consecutive sections. .

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

Further, in the polishing slurry for glass of the present invention, preferably, when the average particle diameter is in the range of 5 nm to 20 nm, the first peak appears in the range of 5 nm to 20 nm, and the second peak appears in the range of 25 nm to 60 nm. When there are two peaks at such a position, the arithmetic mean surface roughness (Ra) of the polished surface of the glass becomes a very low value, and the grinding is performed by the average particle diameter of 5 nm to 20 nm and having only the first peak. The polishing rate is five times higher than that of the abrasive material composed of the material particles. When the first peak deviates from the range of 5 nm to 20 nm, that is, when the thickness is less than 5 nm, the polishing rate tends to be low, and when it exceeds 20 nm, the arithmetic mean surface roughness (Ra) of the polished surface of the glass is liable to change. Big tendency. Further, when the second peak deviates from the range of 25 nm to 60 nm, that is, when it is less than 25 nm, the polishing speed becomes difficult to increase, and when it exceeds 60 nm, the maximum particle diameter Tmax of the abrasive material particles tends to exceed 90 nm, and becomes It is easy to cause abrasive materials such as scratches.

In the polishing slurry for glass of the present invention, the abrasive material is preferably colloidal ceria, colloidal silica, or a mixture of colloidal cerium oxide and colloidal cerium oxide. More preferably, it is colloidal cerium oxide. This is because when the polishing is performed using these abrasive materials, the arithmetic mean surface roughness (Ra) of the surface to be polished of the glass is easily controlled to 0.1 nm. Further, especially when colloidal cerium oxide is used, the cleaning property of the glass after polishing is good, and it is preferable that the surface of the glass does not easily leave abrasive particles.

The polishing slurry for glass of the present invention can be produced in the following manner. First, in the case of colloidal cerium oxide, since spherical cerium oxide having a uniform particle diameter is commercially available, it is possible to produce two kinds of cerium oxide having different particle diameters. That is, a commercially available product having a large particle diameter (referred to as a large particle diameter) and a commercially available product having a small particle diameter (referred to as a small particle diameter) are appropriately mixed to satisfy an average particle diameter of a large particle size/small particle. A commercially available product having two types of the relationship between the average diameter of the radial particles ≧3 and the average particle diameter of the large-sized particles ≦90 nm makes it possible to produce the colloidal cerium oxide which is the polishing slurry for glass of the present invention. When the value of the average particle diameter of the large particle diameter/the average particle diameter of the small particle diameter is close to 3, if the amount of the small particle diameter is not increased, the mixture may not satisfy Tmax/Tavg≧3. In the case of colloidal cerium oxide, since the particle diameter is relatively uniform, the average particle diameter of the Tmax-based larger particle size of the mixture is only slightly larger. Therefore, if two types of colloidal cerium oxide satisfying the relationship between the average particle diameter of the large particle diameter/the average particle diameter ≧3 of the small particle diameter are not mixed, it is difficult for the mixture to satisfy Tmax/Tavg ≧3.

Further, in the case where the polishing slurry for glass of the present invention is produced by colloidal cerium oxide (i.e., ceric oxide), it can be produced in the following manner. The cerium oxide to be an abrasive is a method of oxidizing cerium (III) hydroxide to produce a cerium-based abrasive composed of cerium oxide, preferably chlorine in an inert gas atmosphere such as a nitrogen gas or an argon gas. The hydrazine is reacted with an alkaline substance to produce cerium (III) hydroxide, and the cerium hydroxide is oxidized to form cerium oxide. Further, the so-called (III) system indicates that the valence of ruthenium is trivalent.

In the method for producing cerium oxide, cerium chloride is allowed to react with a basic substance in an inert gas atmosphere. However, when the reaction is carried out under such conditions, the reaction is rapidly performed, so that cerium hydroxide is generated. The particles become fine tetragonal crystals, and the tetragonal crystals are oxidized, whereby cubical and fine polygonal particles can be produced. Next, the particle diameter of the obtained cerium oxide particles can be adjusted by controlling the reaction of cerium chloride with a basic substance.

Specifically, the reaction system for producing cerium (III) hydroxide can be carried out by adding a basic substance such as cesium chloride or sodium hydroxide to the solvent at a constant rate of addition, but changing the rate of addition at this time. Thereby, cerium oxide of different particle diameters can be produced. For example, the reaction can be carried out by a method in which a ruthenium chloride and a basic substance are simultaneously dropped in a solvent, or a ruthenium chloride is immediately sheared after being brought into contact with an alkaline substance. According to this method, gelation at the time of the reaction can be suppressed, and cerium (III) hydroxide can be produced in a uniform cubic shape. Therefore, the oxidation step becomes easy to proceed uniformly, and cerium oxide having a uniform particle diameter and fine particles can be obtained.

Further, the reaction of cerium chloride with a basic substance is preferably carried out at a liquid temperature of 60 ° C to 104 ° C and a pH of 5 to pH 9. In the case where cerium nitrate or cerium ammonium nitrate other than cerium chloride is used as a raw material, the particle diameter tends to become large. When the liquid temperature at the time of the reaction is less than 60 ° C, it tends to become high viscosity and it is difficult to stir, and when it is higher than 104 ° C, it must be carried out under relatively high pressure conditions. Further, when the pH is less than 5, the particle diameter tends to become large, and when it exceeds pH 9, the particle shape tends to become a rod shape, and the polishing property tends to be deteriorated.

Next, cerium (III) hydroxide obtained by the above method is oxidized using an oxidizing agent to produce cerium oxide. As the oxidizing agent, hydrogen peroxide water, hypochlorous acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, ozone or the like can be used.

According to the above production method, colloidal cerium oxide having two different particle diameters is prepared and mixed, whereby the polishing slurry for glass of the present invention can be produced. The mixed colloidal cerium oxide is preliminarily produced with a large particle size (referred to as a large particle size cerium oxide) and a small particle size (referred to as a small particle size cerium oxide), and further mixed to satisfy the following conditions. The conditions are preferably a large particle size cerium oxide average particle diameter/small particle size cerium oxide average particle size ≧2, a large particle size cerium oxide average particle size ≦70 nm, more preferably a large particle size cerium oxide average particle size/small particle size. The average particle diameter of cerium oxide is ≧3, and the average particle diameter of large-sized cerium oxide is ≦60 nm. The mixture was mixed under such conditions, and the mixture satisfies Tmax/Tavg ≧3. Further, in the case of colloidal cerium oxide, since the particle size distribution is relatively wide, the Tmax of the mixture becomes much larger than the average particle diameter of the large-sized cerium oxide. Therefore, even if the average particle diameter of the large particle size cerium oxide/the average particle diameter of the small particle size cerium oxide is <3, there are still many cases in which the mixture of the two colloidal cerium oxides in this relationship can satisfy Tmax/Tavg ≧3.

According to the present invention, the polished surface of the glass can be polished with high precision and high speed.

Preferred embodiments of the present invention will be described in detail with reference to the embodiments and comparative examples.

[Example 1]

First, the case of using colloidal cerium oxide will be described. In the case of colloidal cerium oxide, a slurry containing two kinds of cerium oxide having a target average particle diameter of 20 nm and 50 nm was separately produced.

The colloidal cerium oxide having a target average particle diameter of 20 nm was produced in the following manner. First, the aqueous solution of ruthenium chloride was adjusted to 250 g/L in terms of ruthenium oxide, and the ruthenium hydroxide was adjusted to 174.5 g/L. Next, 73 L of pure water was placed in a 200 L reaction vessel, and the mixture was heated to 90 ° C or higher to carry out deaeration treatment. Next, 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 tank an inert atmosphere.

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

In the reaction tank, precipitation was started when the aqueous solution of ruthenium chloride and the aqueous solution of sodium hydroxide were put into the tank, and the slurry was brought from the time point, and the stirring in the tank (stirring speed: 250 rpm) was continued to carry out a certain degree of ripening treatment. Thereby the slurry in the tank becomes a uniform slurry. Next, the cerium (III) hydroxide slurry was subjected to a aging treatment at a liquid temperature of 90 ° C or higher for 10 minutes until the reaction was completed. Thereafter, 2400 mL of 12% by mass of 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, the obtained slurry was recovered, and subjected to depurination treatment by a cross flow type filter until the Na ion in the slurry was <10 ppm, and the Cl ion was <100 ppm. The solid component in the obtained slurry was analyzed by X-ray diffraction (XRD) and identified as cerium (IV) oxide.

Further, the method for producing colloidal cerium oxide having a target average particle diameter of 50 nm is the same as the method for producing colloidal cerium oxide having a target average particle diameter of 20 nm, and the difference is that the cerium chloride aqueous solution and the sodium hydroxide aqueous solution are mixed in the reaction tank. . In the case of colloidal cerium oxide having a target average particle diameter of 50 nm, in the mixing tank of the reaction tank, only the aqueous solution of cerium chloride was supplied to the reaction tank at a flow rate of 190 mL/min at a flow rate of 200 mL/min. The mixture was mixed without vigorous stirring. By this mixing reaction, a purple precipitate is produced in the reaction tank. X-ray diffraction analysis (XRD) of the obtained precipitate was identified as cerium (III) hydroxide.

In the reaction tank, precipitation was started when the aqueous solution of ruthenium chloride and the aqueous solution of sodium hydroxide were put into the tank, and the slurry was brought from the time point, and the stirring in the tank (stirring speed: 250 rpm) was continued to carry out a certain degree of ripening treatment. Thereby the slurry in the tank becomes a uniform slurry. Next, the cerium (III) hydroxide slurry was subjected to a aging treatment at a liquid temperature of 90 ° C or higher for 10 minutes until the reaction was completed. Thereafter, 2400 mL of 12% by mass of 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, the obtained slurry was recovered and subjected to depurination treatment with a sweep type filter until the Na ion in the slurry was <10 ppm and the Cl ion was <100 ppm. The solid component in the obtained slurry was analyzed by X-ray diffraction (XRD) and identified as cerium (IV) oxide.

The colloidal cerium oxide having a target average particle diameter of 20 nm obtained in the above manner was measured in a 2 L beaker in a solid content of 57 g, and the colloidal cerium oxide having a target average particle diameter of 50 nm was measured and measured in a solid content of 143 g. Put in a 2L beaker. Next, pure water was added to a 2 L beaker, and the content was changed to 2000 g, and a slurry composed of colloidal cerium oxide having a solid concentration adjusted to 10% by weight was prepared (Example 1). The polishing of the quartz was evaluated using the slurry. The polishing evaluation was performed by investigating the polishing rate and the surface roughness of the surface to be polished.

The polishing test was carried out using a single-side polishing machine (manufactured by MAT Inc., Japan). The polishing conditions were obtained by using quartz glass (diameter: 60 mm) as a workpiece and polishing using a polishing pad made of polyurethane. Next, the 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 the polishing machine rotation speed was set to 60 rpm for 30 minutes. The polishing treatment was performed for 30 minutes, and the glass mass before and after the polishing was measured, and the amount of reduction in the glass quality by polishing was determined, and the polishing rate was determined from the value. Regarding the polishing precision, the surface to be polished of the glass obtained by the polishing was washed with pure water, and the surface to be polished was dried in a dust-free state, and the polishing precision was evaluated. The surface roughness is measured by an atomic force microscope (AFM); Atomic Force Microscope (AFM); a nanosecond oscilloscope (NanoScope IIIA) manufactured by Japan Veeco Co., Ltd. for the surface to be polished of the polished glass in a measurement range of 10 μm × 10 μm. The surface roughness value Ra of the surface to be polished.

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

(Comparative Example 1)

For comparison, a slurry of colloidal cerium oxide using only the above-mentioned target average particle diameter of 20 nm was produced. The colloidal cerium oxide having a target average particle diameter of 20 nm used in the above Example 1 was metered into a 2 L beaker in a solid content of 200 g, and pure water was added thereto to make the content 2000 g. Thus, a slurry composed of a colloidal cerium oxide having a target average particle diameter of 20 nm adjusted to have a solid concentration of 10% by weight was prepared. The polishing of the quartz was evaluated using the slurry. The polishing evaluation method was the same as in Example 1.

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

(Comparative Example 2)

For comparison, a slurry of colloidal cerium oxide using only the above-mentioned target average particle diameter of 50 nm was produced. The colloidal ceria having a target average particle diameter of 50 nm was measured in a 2 L beaker in terms of a solid content of 200 g, and pure water was added to make the content 2000 g. Thus, a slurry composed of colloidal cerium oxide having a particle diameter of about 50 nm was prepared to have a solid concentration adjusted to 10% by weight. The polishing of the quartz was evaluated using the slurry. Grinding evaluation method Example 1 is the same.

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

[Embodiment 2]

Next, the case of using colloidal cerium oxide will be described. A colloidal cerium oxide having an average particle diameter of about 20 nm (trade name "CONPAUL", manufactured by FUJIMI INCORPORATED, Japan) was measured in a solid content of 57 g, and was measured in a 2 L beaker. Then, colloidal cerium oxide (trade name "CONPAUL80"; manufactured by FUJIMI INCORPORATED Co., Ltd., Japan) having an average particle diameter of about 80 nm was measured and measured in a solid content ratio of 143 g, and further poured into a 2 L beaker.

Pure water was added to a 2 L beaker to which two kinds of colloidal cerium oxide were charged, and the content was made into 2000 g, and the slurry which consists of colloidal cerium oxide whose solid content concentration was adjusted to 10 weight% was produced. The polishing of the quartz was evaluated using the slurry. The polishing evaluation was the same as in the above Example 1.

In the slurry of Example 2, the polishing rate was 0.05 μm/min, and the arithmetic mean surface roughness (Ra) of the polished surface was 0.081 nm.

(Comparative Example 3)

For comparison, a slurry using only colloidal ceria having a particle diameter of about 20 nm as described above was produced. The colloidal ceria having a particle diameter of about 20 nm used in the above Example 2 was measured in a 2 L beaker in terms of a solid content of 200 g, and pure water was added thereto to make the content 2000 g. Thus, a slurry composed of colloidal ceria having a particle diameter of about 20 nm was prepared to have a solid concentration adjusted to 10% by weight. The polishing of the quartz was evaluated using the slurry. research The grinding evaluation method was the same as in Example 1.

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

(Comparative Example 4)

For comparison, a slurry using only the above-mentioned colloidal ceria having a particle diameter of about 80 nm was produced. In Comparative Example 4, a slurry was prepared using the same conditions as in Comparative Example 1 except that the colloidal ceria having a particle diameter of about 80 nm used in Example 2 was used. Next, the polishing evaluation of the quartz was performed using the slurry. The polishing evaluation method was the same as in Example 1.

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

Next, the results of investigating the particle size distribution will be described for each of the examples and comparative examples.

Tables 1 to 6 show the results of investigating the particle size distribution of the abrasive particles of the respective examples and comparative examples. The particle size distribution was prepared in the following manner.

The particle diameter (TEM diameter) obtained by a transmission electron microscope is specified in the following manner. First, a TEM image was taken using a transmission electron microscope to take a magnification of 200 to 1000 particles in one field of view. Next, a tracing paper or an OHP (overhead projector) sheet was placed on the TEM image to depict the outline of all the particles. 1 and 2 show a TEM image of the first embodiment and a drawing surface thereof, and FIGS. 3 and 4 show a TEM image of the comparative example 1 and a drawing surface thereof, and FIG. 5 and FIG. The figure shows the TEM image of Comparative Example 2 and its depiction. The surface of the obtained drawing was read by a scanner (flat head scanner CanonScan 8200F: output resolution 400 dpi), and image-measurement software (Image Pro Plus: manufactured by Cybernetics) was used to measure at 2° scale. By measuring the center of gravity of the object (each particle), the average value is taken as the particle diameter of the particle, and the particle diameter of all the particles that have been electronically encoded is measured, and the total number of particles is divided by the number of particles, thereby specifying the average particle. In addition, the number of particles of the particle diameter section described in the following Tables 1 to 6 is counted as a particle size distribution table in accordance with the particle diameter value of each particle.

Since the maximum particle diameter of the abrasive particles in the present embodiment is 90 nm, the interval of the particle size distribution is set at a interval of 5 nm between 0 and 100 nm. The respective particle size distribution tables are shown below.

From the results of Tables 1 to 3 and the evaluation of the polishing, it is understood that in the case of colloidal cerium oxide, as shown in Example 1, the particle size distribution has two peaks, and the maximum particle diameter Tmax and the average particle diameter Tavg satisfy Tmax. In the case of /Tavg≧3, it was found that the surface roughness of the surface to be polished was the same as that of Comparative Example 1, but the polishing rate became nearly 30 times faster. Further, as compared with Comparative Example 2, it was found that although the polishing rate was slightly slow, the surface roughness of the surface to be polished became small.

From the results of Tables 4 to 6 and the evaluation of the polishing, it is understood that in the case of colloidal cerium oxide, as shown in Example 2, the particle size distribution has two peaks, and the maximum particle diameter Tmax and the average particle diameter Tavg satisfy. In the case of Tmax/Tavg≧3, it was found that the surface roughness of the surface to be polished was the same as that of Comparative Example 3, but the polishing rate became nearly 25 times faster. Further, as compared with Comparative Example 4, the polishing speed became faster than 3 times, and the surface roughness of the surface to be polished became small.

(industrial availability)

The polished surface of the glass can be processed with high precision, and the glass can be polished at a high speed.

Fig. 1 is a TEM image of Example 1.

Fig. 2 is a drawing of the first embodiment.

Fig. 3 is a TEM image of Comparative Example 1.

Fig. 4 is a drawing of Comparative Example 1.

Fig. 5 is a TEM image of Comparative Example 2.

Fig. 6 is a drawing of Comparative Example 2.

Since the picture in this case is a photograph and a drawing of the material structure, it is not a representative figure of the case, so there is no designated representative figure in this case.

Claims (2)

A polishing slurry for glass characterized in that a maximum particle diameter Tmax of the abrasive material particles measured by a transmission electron microscope is 90 nm or less, and the maximum particle diameter Tmax and the abrasive material particles measured by a transmission electron microscope The average particle diameter Tavg satisfies Tmax/Tavg ≧3, and the particle size distribution of the abrasive material particles has at least a first peak appearing near the average particle diameter value and a second peak appearing near the particle diameter value three times or more of Tavg, wherein The first peak appears in the range of 5 nm to 20 nm, and the second peak appears in the range of 25 nm to 60 nm, wherein the abrasive material is colloidal cerium oxide. The glass slurry according to claim 1, wherein the average particle diameter is from 5 nm to 20 nm.