TWI705947B - Grinding method of negatively charged substrate and manufacturing method of negatively charged substrate with high surface smoothness - Google Patents

Abstract

The present invention provides a method for polishing a negatively charged substrate with excellent surface smoothness, which can achieve a high polishing speed and has good productivity. In addition, a method for manufacturing a negatively charged substrate with high surface smoothness is provided.

The present invention is a method for polishing a negatively charged substrate, which is a method of polishing a negatively charged substrate using an abrasive slurry. The abrasive slurry contains a composition formula: ABO ₃ (A represents selected from the group consisting of Sr and Ca At least one element in the group. B represents at least one element selected from the group consisting of Ti, Zr, and Hf) and zirconium oxide. The polishing method is each performed at least once Polishing step a of polishing the negatively charged substrate under the condition that the zeta-potential of the polishing material slurry becomes positive, and polishing step b of polishing the negatively charged substrate under the condition that the zeta-potential of the polishing material slurry becomes negative .

Description

Polishing method of negatively charged substrate and manufacturing method of negatively charged substrate with high surface smoothness

The present invention relates to a method for polishing a negatively charged substrate and a method for manufacturing a negatively charged substrate with high surface smoothness.

A glass substrate is a representative example of a negatively charged substrate. The glass substrate is polished by using abrasive materials, which can provide precision optical glass products such as lenses or ridges that require high transparency or precision.

Previously, in the grinding of glass substrates, the process of rough grinding the glass substrate with a cerium oxide-based grinding material was first performed, and then in order to improve the smoothness of the surface of the glass substrate, colloidal silica was used for precision. The step of grinding. In addition, recently, the industry has also developed a polishing method using cerium oxide in a plurality of polishing steps (refer to Patent Document 1).

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Application Publication No. 2014-83598

As mentioned above, the previous glass substrate is generally subjected to a precise polishing step using colloidal silica after the rough polishing step using a cerium oxide-based abrasive material. However, in this method, since the abrasive is switched from the cerium oxide-based abrasive to colloidal silica, it is necessary to perform the switching operation or the glass substrate cleaning operation. In addition, in order to prevent the cerium oxide-based abrasive from being brown For the cleaning operation of the grinder and device or the coloring of other materials, there are also situations where it is necessary to use a special grinder or device for the use of cerium oxide-based abrasives, and there are problems in the operation or equipment. In addition, since the polishing step using colloidal silica is very slow, there are also problems in this respect.

In addition, cerium oxide-based abrasives are produced by calcining and crushing minerals containing a large amount of so-called rare earth elements (rare earths). The demand for rare earth elements increases and the supply becomes unstable. Therefore, it is expected to develop a technology to reduce the amount of cerium oxide used or a technology to use substitute materials. The grinding method that must use cerium oxide (for example, the method of Patent Document 1, etc.) cannot meet this requirement.

In view of the above-mentioned current situation, the present invention aims to provide a polishing method that can realize a high polishing speed and provide a negatively charged substrate with excellent surface smoothness with good productivity. Moreover, its purpose is to provide a method for manufacturing a negatively charged substrate with high surface smoothness.

The inventors conducted various studies on polishing methods for negatively charged substrates represented by glass substrates, and found that the zeta potential of a polishing material slurry containing a specific oxide and zirconia becomes positive by performing each at least once The step a of grinding under the condition that the zeta potential of the polishing material slurry becomes negative, the step b of grinding can be realized, and higher grinding speed can be achieved. The present invention is completed by considering that the above-mentioned problems can be completely solved by providing a negatively charged substrate with excellent surface smoothness with good productivity and high productivity.

That is, the present invention is a method for polishing a negatively charged substrate, which is a method of polishing a negatively charged substrate using an abrasive slurry. The abrasive slurry contains a composition formula: ABO ₃ (A represents selected from Sr and Ca At least one element in the group consisting of Ti, Zr, and Hf. B represents at least one element selected from the group consisting of Ti, Zr, and Hf) and zirconium oxide (zirconium oxide). Next to the polishing step a of polishing the negatively charged substrate under the condition that the zeta potential of the polishing material slurry becomes positive, and the polishing step b of polishing the negatively charged substrate under the condition that the zeta potential of the polishing material slurry becomes negative.

The above-mentioned oxide is preferably SrZrO ₃ and/or CaZrO ₃ . The polishing material slurry contains strontium zirconate (SrZrO ₃ ) and/or calcium zirconate (CaZrO ₃ ) and zirconium oxide (ZrO ₂ ) to achieve a higher polishing speed. As the above oxide, SrZrO _{3 is} most preferable.

Preferably, the polishing step a is performed under the condition that the pH value of the abrasive slurry is greater than the isoelectric point of the negatively charged substrate and does not reach the isoelectric point of the abrasive slurry. Thereby, the burden on the polishing device and the tool is reduced, so it becomes a more advantageous manufacturing method in terms of work, and it can sufficiently prevent the polishing material from dissolving under strong acid. In addition, the polishing speed can be further increased.

Preferably, the above-mentioned polishing step b is performed under the condition that the pH value of the abrasive slurry is greater than the isoelectric point of the abrasive slurry and becomes 13 or less. Thereby, the burden on the polishing device and the tool is reduced, and it becomes a more advantageous manufacturing method in terms of work. In addition, it is possible to sufficiently prevent the polishing material from dissolving under strong alkali. In addition, the surface smoothness of the obtained substrate can be further improved.

The negatively charged substrate is preferably a glass substrate. In this way, it can be more fully distributed Play based on the effects of the present invention.

In addition, the present invention is also a method of manufacturing a negatively charged substrate with high surface smoothness using the above-mentioned polishing method.

According to the method for polishing a negatively charged substrate of the present invention, only one type of polishing material that does not contain cerium oxide as the main component can be used to achieve a high polishing speed and provide a negatively charged substrate with excellent surface smoothness with good productivity . Therefore, the polishing method of the present invention does not require the switching of the polishing material required in the conventional polishing method (a method of performing a precise polishing step using colloidal silica after the rough polishing step using a cerium oxide-based abrasive material). Work or cleaning operations, special equipment, etc., and can adequately cope with the shortage of rare earth elements in recent years, so it can be called an extremely advantageous technology in industry. In addition, if the polishing method of the negatively charged substrate of the present invention is used, the negatively charged substrate with high surface smoothness can be provided with good productivity. Therefore, the high surface smoothness of the negatively charged substrate is manufactured using this polishing method The method can be regarded as an extremely advantageous method in industry.

1‧‧‧Grinding material A

2‧‧‧Glass

3‧‧‧Lapping Pad

4‧‧‧The switching time of the grinding material in the previous grinding method (i)

5‧‧‧The time to reach the target surface roughness in the previous polishing method (i)

6‧‧‧Surface roughness of target

7‧‧‧The time to switch the zeta potential of the polishing material slurry (preferably the pH value of the polishing material slurry) in the polishing method (ii) of the preferred form of the present invention

8. The time to reach the target surface roughness in the polishing method (ii) of the preferred form of the present invention

Fig. 1 shows the X-ray diffraction pattern of zirconia used as the Zr raw material in Manufacturing Example 1.

Fig. 2 is the X-ray diffraction pattern of the abrasive material obtained in Manufacturing Example 1.

Fig. 3 is an SEM image of the abrasive material obtained in Manufacturing Example 1.

Fig. 4 is a graph showing the relationship between the zeta potential of each abrasive slurry used in an embodiment or a comparative example with respect to the pH value.

Figure 5 shows the polishing step a of the glass under the condition that the pH value of the abrasive slurry A becomes 5.5 (Figure 5(a)) and the polishing under the condition that the pH value of the abrasive slurry A becomes 10 The conceptual diagram of the glass grinding step b (Figure 5(b)) on the rough ground glass in step (a).

6 is a graph conceptually showing the relationship between the processing time (grinding time) and the surface roughness of the polishing object in the prior polishing method and the preferred form of the polishing method of the present invention.

An example of the present invention will be specifically described below, but the present invention is not limited to the following description, and can be suitably modified and applied without changing the gist of the present invention.

[Lapping method of negatively charged substrate]

The polishing method of the negatively charged substrate as the first aspect of the present invention will be described.

In this specification, the so-called negatively charged substrate is preferably a substrate that is always negatively charged in an aqueous solution with a pH value greater than 4, for example, a glass substrate (isoelectric point of glass = about 2.0). In addition, silicon carbide substrates (isoelectric point of silicon carbide = about 4.0) and the like can also be cited.

Furthermore, as a glass substrate, transparent or translucent ones, such as soda lime glass, alkali-free glass, borosilicate glass, quartz glass, etc. are mentioned, for example.

In the polishing method of the present invention, the polishing step a of polishing a negatively charged substrate under the condition that the zeta potential of the polishing material slurry becomes positive, and the condition that the zeta potential of the polishing material slurry becomes negative are respectively performed at least once The polishing step b of polishing the negatively charged substrate. The order of the polishing steps is not particularly limited. The polishing step b can be performed after the polishing step a, or the polishing step a can be performed after the polishing step b. Among them, in order to obtain a more excellent surface smoothness, negative chargeability For the substrate, it is particularly preferable to perform the polishing step b at least once after the polishing step a is performed at least once. In addition, each polishing step may be performed multiple times, or the polishing step a and the polishing step b may be performed alternately. When the polishing step a is performed multiple times, as long as the zeta potential of the polishing material slurry is positive, the zeta potential can be changed and implemented, or the zeta potential can also be implemented without changing the zeta potential. The same is true when the polishing step b is performed multiple times. As long as the zeta potential of the polishing material slurry is negative, the zeta potential can be changed and implemented, or it can be implemented without changing the zeta potential.

In this specification, the "ζ potential of the polishing material slurry" is a value obtained under the measurement conditions described in the examples described later.

It can be inferred that in the present invention, the action based on electrostatic attraction is exerted in the polishing step a, and the action based on the electrostatic repulsion in the polishing step b is exerted, and these synergistic effects are used to achieve higher polishing speed and negative charging after polishing. Excellent surface smoothness of the substrate.

Generally, the surface of the negatively-charged substrate before polishing has recesses composed of fine cracks or holes. It can be considered that the substrate to be polished in the polishing step a is negatively charged, and the polishing material slurry is positively charged. Therefore, the electrostatic attractive polishing material penetrates into the depths of the recesses to promote polishing, thereby increasing the polishing speed. On the other hand, it can be considered that in the polishing step b, the substrate to be polished and the polishing material slurry are both negatively charged, so the polishing material does not penetrate deep into the recess due to electrostatic repulsion, but is applied to the polishing pad and the substrate. Due to the pressure between them, a large amount of abrasives exist on the convex parts of the substrate surface, thereby smoothing the substrate surface. Therefore, if the object to be polished is a negatively charged substrate, it becomes the same mechanism. Therefore, the polishing method of the present invention can be applied not only to glass substrates, but also to various negatively charged substrates.

Here, FIG. 5 is used to illustrate the mechanism of the preferred form of the polishing method of the present invention, but the polishing method of the present invention is not limited to the method shown in the figure.

Figure 5 shows the condition where the abrasive slurry A obtained in Example 1 (a composite of SrZrO ₃ and ZrO ₂ as an abrasive. Isoelectric point: 6.4) is used when the pH of the abrasive slurry A becomes 5.5 A conceptual diagram of the case where the glass polishing step is performed (Figure (a)) and the case where the pH value of the polishing material slurry A is 10 (Figure (b)).

First, when the polishing material slurry A is supplied to the polishing pad (symbol 3) and the glass (symbol 2) is being polished at the same time, the polishing material A (symbol 1) is positive under the condition of pH=5.5 Therefore, the abrasive material A can be adsorbed on the negatively charged glass, and penetrate into the depth of the fine concave and convex parts of the glass surface. That is, this step can be called a rough grinding step, and the grinding speed is significantly higher.

On the other hand, when the polishing step is performed under the condition of pH=10 after the above polishing step, the polishing material A (symbol 1) is negatively charged, so the polishing material rebounds from the negatively charged glass, and the polishing material selectively grinds the glass The convex part of the surface. That is, this step can be called a precision polishing step. Although the polishing speed is low, the surface smoothness of the polishing object (glass in FIG. 5) is significantly improved.

In addition, as FIG. 6, the relationship between the processing time (polishing time) and the surface roughness of the polishing object in the conventional polishing method (i) and the preferred embodiment (ii) of the polishing method of the present invention is conceptually shown in Graph, but the polishing method of the present invention is not limited to the method (ii) shown in the graph.

In the conventional polishing method (i), as in Comparative Example 1 described later, the cerium oxide-based abrasive is first used for rough polishing until the time of symbol 4, then the polishing material (symbol 4) is switched, and then the second colloid is used. The silicon oxide is precisely polished to achieve the target surface roughness (symbol 6).

On the other hand, in the preferred form (ii) of the polishing method of the present invention, the rough polishing based on the polishing step a is first performed until the time point of symbol 7, and then the zeta potential of the polishing material slurry is switched (preferably the polishing material The pH value of the slurry) (symbol 7), after which, the precision grinding based on the grinding step b Grinding to achieve the target surface roughness (symbol 6). The achievement time (symbol 8) is sufficiently shorter than that of the conventional polishing method (symbol 5).

Any one of the above-mentioned polishing step a and polishing step b is polished in the presence of the polishing material slurry. In the polishing step a and the polishing step b, the same polishing material slurry can be used, that is, continuous use (reuse), only the zeta potential of the slurry is controlled, and the zeta potential can also be prepared differently to be positive or negative. The polishing material slurry is switched in each polishing step. In either case, it is sufficient to use the one containing the oxide represented by the composition formula: ABO ₃ and zirconia as the abrasive slurry. In this way, the polishing material slurry can be continuously used (reused) in the present invention. Even when switching, there is no need to prepare a large difference in type of polishing material slurry, so there is no need to switch the polishing material as in the conventional method. Required cleaning operations or special equipment, etc. Furthermore, even if cerium oxide is not necessary, a higher polishing speed and excellent surface smoothness can be achieved. Therefore, the polishing method of the present invention can be described as a very advantageous method compared with the conventional polishing method.

The above-mentioned polishing step a is a step of polishing a negatively charged substrate with the polishing material slurry under the condition that the zeta potential of the polishing material slurry becomes positive. In this polishing step, it is possible to achieve a high polishing speed that is approximately the same as that in the case of using cerium oxide-based abrasives in the past, and it is also possible to improve the surface smoothness of the negatively charged substrate compared to the case of using cerium oxide-based abrasives.

The above-mentioned polishing step b is a step of polishing a negatively charged substrate with the polishing material slurry under the condition that the zeta potential of the polishing material slurry becomes negative. In this grinding step, a significantly higher grinding speed than the previous precision grinding step using colloidal silica can be achieved, and the precision grinding is roughly the same as the precision grinding step using colloidal silica, which can be negatively charged after grinding Achieve high surface smoothness in a flexible substrate.

As mentioned above, in the polishing step a of the present invention, the zeta electricity of the polishing material slurry The negatively charged substrates are polished separately under the condition that the potential becomes positive and the zeta potential of the polishing material slurry becomes negative in the polishing step b. Preferably, the absolute value of the zeta potential of the polishing material slurry becomes 5mV or more. Each grinding step is performed under the conditions. Thereby, the effects of the present invention can be more fully exerted. Each is more preferably 10 mV or more, still more preferably 15 mV or more, and particularly preferably 20 mV or more. In addition, the upper limit of the absolute value in each step is not particularly limited. For example, it is easy to control (for example, if the zeta potential is too large in the polishing step a, there is a possibility that the polishing material may remain on the surface of the glass substrate, so this case is performed In addition, for example, if the zeta potential is too low in the polishing step b, the electrostatic repulsion between the negatively charged substrate and the polishing material slurry may be too strong, and the polishing speed may not be sufficiently increased. From the viewpoint of prevention etc.), each is preferably 100 mV or less.

The zeta potential of the abrasive slurry can be controlled by adjusting the pH value of the abrasive slurry. If the abrasive slurry contains the composition formula: oxide and zirconia represented by ABO ₃ , when the pH of the abrasive slurry is adjusted to less than the isoelectric point of the abrasive slurry, its zeta potential becomes Positive, on the other hand, when the pH of the abrasive slurry is adjusted to exceed the range of the isoelectric point of the abrasive slurry, the zeta potential becomes negative. In addition, the abrasives used to date have focused on improving the polishing speed or improving the surface smoothness. The abrasives used in the present invention are those that can easily control the abrasiveness by using only the pH value. Special effects that technology cannot conceive.

The pH value can be adjusted by adding a pH adjuster to the polishing material slurry, and the pH value of the polishing material slurry can also be adjusted by using a pH buffer solution.

Furthermore, when the pH value of the polishing material slurry is already in a preferable range for polishing, the pH value adjustment may not be performed.

As the above-mentioned pH adjuster, an acid or a base can be used. If acid is used, The pH value of the abrasive slurry is adjusted to the acidic side. If alkali is used, the pH value of the abrasive slurry can be adjusted to the alkaline side. As the acid, for example, inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, and phosphoric acid, and organic acids such as oxalic acid and citric acid are preferred. As the base, for example, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and calcium hydroxide are preferred. Alkaline aqueous solutions such as aqueous solutions, sodium carbonate aqueous solutions, ammonia water, and sodium bicarbonate aqueous solutions.

In the polishing method of the present invention, it is preferable to perform the polishing step a under the condition that the pH of the polishing material slurry is greater than the isoelectric point of the negatively charged substrate and does not reach the isoelectric point of the polishing material slurry. Thereby, it is possible to sufficiently suppress the dissolution of the abrasive material due to strong acid, further exert the polishing effect of the abrasive material, and also reduce the burden on the grinder and the device. As the lower limit of the pH value of the abrasive slurry in the polishing step a, specifically, it is preferably 2 or more. More preferably, it is 3 or more, More preferably, it is 4 or more.

Furthermore, it is preferable to perform the polishing step b under the condition that the pH of the polishing material slurry is greater than the isoelectric point of the polishing material slurry and becomes 13 or less. Thereby, it is possible to sufficiently suppress the dissolution of the abrasive by the strong alkali, further exert the polishing effect by the abrasive, and also reduce the burden on the grinder and the device. The upper limit of the pH value of the abrasive slurry in the polishing step b is more preferably 12 or less. More preferably, it is 11 or less.

In this specification, the so-called isoelectric point of the abrasive slurry (and abrasive) refers to the point where the algebraic sum of the charge carried by the abrasive particles (abrasive material) in the abrasive slurry is zero, that is, the point at which the abrasive particles carry The point where the positive charge and the negative charge become equal can be expressed by the pH value of the abrasive slurry at that point. For reference, for example, an abrasive composed of a composite of CaZrO ₃ and ZrO ₂ (Ca content: 27% by weight in terms of CaO) has an isoelectric point of 6.1, and a composite of CaTiO ₃ and ZrO ₂ (Ca content: The isoelectric point of the abrasive composed of 30% by weight in terms of CaO is 5.9, and the isoelectric point of the abrasive composed of a composite of SrTiO ₃ and ZrO ₂ (Sr content: 40% by weight in terms of SrO) Is 5.7.

〈Abrading material slurry〉

Next, the polishing material slurry used in the polishing method of the present invention will be described.

The abrasive slurry contains the composition formula: ABO ₃ (A represents at least one element selected from the group consisting of Sr and Ca. B represents at least one element selected from the group consisting of Ti, Zr and Hf) The indicated oxide and zirconia.

In this specification, the oxide represented by the composition formula: ABO ₃ is also referred to as "ABO ₃ oxide", and the one composed of ABO ₃ oxide and zirconia is also referred to as "abrasive material".

The content of the abrasive (the total amount of ABO ₃ oxide and zirconia) in the abrasive slurry is preferably 0.001 to 90% by weight in 100% by weight of the abrasive slurry. More preferably, it is 0.01 to 30% by weight.

The above-mentioned abrasive slurry preferably further contains a dispersion medium.

烷等，作為醇，可列舉：甲醇、乙醇、丙醇等一元水溶性醇；乙二醇、甘油等二元以上之水溶性醇等。作為分散介質，較佳為水，更佳為離子交換水。 It does not specifically limit as a dispersion medium, For example, water, an organic solvent, or a mixture of these etc. are mentioned, 1 type, or 2 or more types can be used. Examples of organic solvents include alcohol, acetone, dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, two

Alkanes and the like. Examples of alcohols include monovalent water-soluble alcohols such as methanol, ethanol, and propanol; and divalent or more water-soluble alcohols such as ethylene glycol and glycerin. As the dispersion medium, water is preferred, and ion exchange water is more preferred.

In addition, the above-mentioned abrasive slurry may optionally contain one or more additives within a range that does not hinder the effects of the present invention. The additives are not particularly limited, and examples include pH adjusters (acids, alkalis, etc.), chelating agents, defoamers, dispersants, viscosity adjusters, anti-aggregating agents, lubricants, reducing agents, and rust inhibitors. , Well-known abrasive materials, etc.

Furthermore, from the viewpoint of improving the effect of the polishing method based on the present invention, the content of additives other than the pH adjuster is as small as possible. For example, relative to 100% by weight of the total amount of the abrasive slurry, the content of additives other than the pH adjuster is preferably 5% by weight or less. In other words, in 100% by weight of the total amount of the abrasive slurry, the abrasive, the dispersion medium, and the pH adjuster are preferably at least 90% by weight, more preferably at least 95% by weight, and even more preferably at least 99% by weight.

As long as the dresser slurry containing zirconium oxide ABO ₃ who is not particularly limited, preferably the oxide ABO ₃ containing zirconium oxide in the form of a complex of these. That is, the abrasive composed of ABO ₃ oxide and zirconia is preferably a composite of ABO ₃ oxide and zirconia. In other words, the abrasive slurry in the present invention preferably contains the composition formula: ABO ₃ (A represents at least one element selected from the group consisting of Sr and Ca. B represents the element selected from the group consisting of Ti, Zr and Hf A composite of oxide and zirconia represented by at least one element in the group) is used as an abrasive. Thereby, a higher polishing speed can be further realized in the abrasive material without cerium. Note that the ABO ₃ complex oxide and zirconium oxide secondary particle system refers ABO ₃ oxide and zirconium oxide are each of the primary particles is formed of a sintered part. For example, if the composite is subjected to element mapping using energy dispersive X-ray spectroscopy (EDS), it is possible to observe the primary particles that detect the elements contained in A and the elements contained in B, and those that only detect Zr. A situation in which primary particles form secondary particles.

As the above-mentioned abrasive, it is more preferable to include a crystal phase of ABO ₃ oxide and a crystal phase of zirconium oxide (ZrO ₂ ). The crystalline phase of ABO ₃ oxide contained in the polishing material exerts a chemical polishing effect, and the crystalline phase of ZrO ₂ exerts a mechanical polishing effect, which can show a better polishing speed. Furthermore, when the ABO ₃ oxide and ZrO ₂ form a composite body, the chemical polishing effect based on the ABO ₃ oxide and the mechanical polishing effect based on the ZrO ₂ crystal phase can be more effectively performed.

The crystalline phases of the above oxides ABO _3, particularly preferably SrZrO ₃ and / or CaZrO ₃ of the crystalline phase, and most preferably ₃ SrZrO of crystalline phases. In this case, it is preferable to use CuK α rays as the radiation source in the X-ray diffraction of the peaks derived from the (040) plane of orthorhombic SrZrO ₃ and/or the peaks derived from the (121) plane of CaZrO ₃ The half-height width is 0.1~3.0°. If the half-height is within this range, the crystallinity of SrZrO ₃ and/or CaZrO ₃ , which effectively exerts the chemical polishing effect, becomes suitable, so that the chemical polishing effect can be fully exerted. It is more preferably 0.1 to 1.0°, still more preferably 0.1 to 0.7°, and particularly preferably 0.1 to 0.4°.

It is preferable that the above-mentioned abrasive material has a ratio of D ₉₀ to D ₁₀ (D ₉₀ /D ₁₀ ), which is an index of the sharpness of the volume-based particle size distribution, of 1.5-50. If D ₉₀ /D _{10 is} in the range of 1.5-50, the difference in particle size becomes moderate, and the abrasive material and the substrate of the polishing object can be fully contacted, so a better polishing rate can be achieved. It is more preferably from 1.5 to 45, and even more preferably from 1.5 to 40.

Furthermore, a larger D ₉₀ /D ₁₀ means a wider particle size distribution, and a smaller value means a narrower particle size distribution.

D ₁₀ and D ₉₀ are values obtained by measuring particle size distribution, respectively. D ₁₀ means 10% cumulative particle size on a volume basis, and D ₉₀ means 90% cumulative particle size on a volume basis.

The abrasive material preferably has a specific surface area of 1.0 to 50 m ² /g. If the specific surface area is 1.0 m ² /g or more, the substrate to be polished can be sufficiently contacted, so polishing can be performed more appropriately. In addition, if it is 50 m ² /g or less, the size of the abrasive grains constituting the abrasive becomes appropriate, so the mechanical polishing effect is further improved. It is more preferably 1.0 to 45 m ² /g, and still more preferably 1.0 to 40 m ² /g.

In this specification, the specific surface area (also referred to as SSA) means the BET specific surface area.

The BET specific surface area refers to the specific surface area obtained by the BET method, which is one of the measurement methods of the specific surface area. Furthermore, the specific surface area refers to the surface area per unit mass of an object.

The BET method makes nitrogen and other gas particles adsorb on the solid particles, and it is measured according to the adsorbed amount Gas adsorption method with fixed specific surface area. Specifically, based on the relationship between the pressure P and the adsorption amount V, the single molecule adsorption amount VM is obtained by the BET formula, thereby determining the specific surface area.

Further, the polishing material is calculated as oxides is preferably 10 to 43 wt% of oxides of elements ABO ₃ A. For example, it is preferable to contain 10 to 43% by weight of Sr in terms of SrO. If it is in this range, the chemical polishing effect and the mechanical polishing effect are further exerted, so the polishing efficiency can be further improved. It is more preferably 11 to 43% by weight, and still more preferably 12 to 43% by weight.

First, the ABO ₃ oxide will be described below.

ABO ₃ oxide system composition formula: ABO ₃ (A represents at least one element selected from the group consisting of Sr and Ca. B represents at least one element selected from the group consisting of Ti, Zr and Hf) Represents the compound.

In the formula, A represents at least one element selected from the group consisting of strontium (Sr) and calcium (Ca), of which Sr is preferred. In addition, B represents at least one element selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf), among which Ti and/or Zr is preferred, and Zr is more preferred.

The above-mentioned ABO ₃ oxide is preferably, for example, by using at least one selected from the group consisting of strontium carbonate, strontium hydroxide, calcium carbonate and calcium hydroxide with titanium oxide, titanium hydroxide, zirconium oxide, and zirconium hydroxide. Obtained by the reaction of at least one of the group consisting of, zirconium carbonate, and hafnium oxide. This reaction is easy to proceed, so ABO ₃ oxide can be easily obtained.

Among the oxides used as raw materials for the production of the above-mentioned ABO ₃ oxides, the production method, shape, crystal type, particle size, etc. of titanium oxide (TiO ₂ ) are not particularly limited. For example, as a method for producing titanium oxide, the chloride method or the sulfuric acid method can also be used. The crystal type may be rutile, anatase, brookite, or a mixture of these. The preparation method, shape, crystal type, particle size, etc. of hafnium oxide (HfO ₂ ) are also not particularly limited. The zirconium oxide (ZrO ₂ ) is also not particularly limited, and preferably has the same form as the zirconium oxide described later.

Examples of the oxides ABO _3, particularly preferably strontium zirconate (SrZrO ₃₎ and / or calcium zirconate (CaZrO _3), most preferably strontium zirconate (SrZrO _3). In this way, a higher polishing speed can be achieved.

Furthermore, strontium zirconate is preferably selected from at least one selected from the group consisting of strontium carbonate and strontium hydroxide and at least one selected from the group consisting of zirconia, zirconium hydroxide, and zirconium carbonate. The response is obtained. This reaction is easy to proceed, so strontium zirconate is easy to produce.

In addition, calcium zirconate is preferably selected from at least one selected from the group consisting of calcium carbonate and calcium hydroxide and at least one selected from the group consisting of zirconia, zirconium hydroxide, and zirconium carbonate. Obtained by reaction. This reaction is easy to proceed, so calcium zirconate is easy to produce.

Next, zirconium oxide (ZrO ₂ ) will be described.

The crystal form of zirconia is preferably any one of monoclinic, tetragonal, and cubic crystal structures or a mixed crystal of these crystal structures.

The above-mentioned zirconia is not particularly limited. For example, it is preferable to use CuK α rays as the radiation source in the X-ray diffraction of the maximum peak of 2 θ = 27.00 ~ 31.00 ° FWHM (hereinafter also referred to as "ZrO ₂ maximum The half-height width of the crest”) is 0.1~3.0°. When the FWHM is 3.0° or less, the crystallinity of ZrO ₂ contained in the abrasive slurry becomes higher, and the mechanical polishing effect derived from ZrO ₂ can be sufficiently obtained. In addition, by having a half-height width of 0.1° or more, a polishing material slurry with a more excellent polishing speed can be obtained. It is more preferably 0.1 to 1.0°, still more preferably 0.1 to 0.7°, and particularly preferably 0.1 to 0.4°.

Furthermore, in this specification, all radiation sources for X-ray diffraction use CuK α rays.

As the abrasive slurry used in the present invention, it is particularly preferable to contain an abrasive composed of strontium zirconate (SrZrO ₃ ) and/or calcium zirconate (CaZrO ₃ ) and zirconium oxide (ZrO ₂ ), more preferably It is a composite body containing strontium zirconate and/or calcium zirconate and zirconia, preferably a composite body containing strontium zirconate and zirconia. The abrasive (composite of strontium zirconate and zirconia) is preferably obtained, for example, by a manufacturing method including a mixing step of mixing a strontium compound and a zirconium compound and a calcining step of calcining the mixture obtained by the mixing step. This manufacturing method is carried out by a solid-phase reaction method, so the manufacturing procedure is simpler than that of the spray thermal decomposition method, no special equipment is introduced, and low-cost manufacturing can be realized. The complex of calcium zirconate and zirconia is also preferably obtained by a production method that is substantially the same (in which, for example, calcium compounds such as calcium carbonate or calcium hydroxide are used instead of strontium compounds).

The steps are further described below.

-Mixed steps-

In the mixing step, the strontium compound and the zirconium compound are mixed. The ratio of raw materials during mixing is ideally SrO:ZrO ₂ =10:90~43:57 in terms of weight ratio converted from oxides.

The mixing method is not particularly limited, and may be wet mixing or dry mixing. From the viewpoint of mixing properties, wet mixing is preferred. The dispersion medium used for wet mixing is not particularly limited, and water or lower alcohol can be used. From the viewpoint of production cost, water is preferred, and ion exchange water is more preferred. In the case of wet mixing, ball mills, paint conditioners, and sand mills can also be used. Furthermore, in order to remove the dispersion medium, it is preferable to perform a drying step after wet mixing.

The above-mentioned strontium compound is not particularly limited as long as it is a compound containing a strontium atom, and among them, it is preferably at least one selected from the group consisting of strontium carbonate and strontium hydroxide. The reaction between strontium carbonate and strontium hydroxide and the zirconium compound is easy to proceed, and strontium zirconate (SrZrO ₃ ) is easily formed.

The zirconium compound is not particularly limited as long as it is a compound containing a zirconium atom. Among them, it is preferably at least one selected from the group consisting of zirconium oxide, zirconium carbonate, and zirconium hydroxide. These have higher reactivity with strontium compounds, and can provide abrasives with better abrasive properties.

Furthermore, when a zirconium compound other than zirconium oxide (such as zirconium carbonate and/or zirconium hydroxide) is used, the steps of calcination and crushing during the synthesis of zirconium oxide can be omitted.

The above-mentioned zirconium compound can also be used in the mixing step in the form of a block obtained in the synthesis.

The specific surface area of the above-mentioned zirconia is preferably 2.0 to 200 m ² /g. Thereby, a polishing material slurry with a more excellent polishing speed can be obtained. It is more preferably 2.0 to 180 m ² /g, and still more preferably 2.0 to 160 m ² /g.

The specific surface area of zirconium compounds other than the above-mentioned zirconium oxide is preferably 0.1 to 250 m ² /g. Thereby, a polishing material slurry with a more excellent polishing speed can be obtained. It is more preferably 0.3 to 240 m ² /g, and still more preferably 0.5 to 230 m ² /g.

When a compound other than zirconium oxide is used as the zirconium compound, the SO ₃ conversion amount of the sulfur compound contained in the zirconium compound is preferably 2.0 parts by weight or less with respect to 100 parts by weight of the ZrO ₂ conversion amount of the zirconium compound. Thereby, a polishing material with a better polishing speed can be obtained. The content of the sulfur compound (in terms of SO ₃ ) is more preferably 1.5 parts by weight or less, still more preferably 1.1 parts by weight or less, and particularly preferably 0.5 parts by weight or less.

In this manual, the SO ₃ conversion amount of the sulfur compound contained in the zirconium compound can be obtained by using a fluorescent X-ray analysis device (manufactured by RIGAKU Co., Ltd.: model ZSX Primus II) as the EZ scan containing the element scanning function. The stamped sample is placed on the measurement sample table, and the following conditions are selected (measurement range: FU; measurement diameter: 30mm; sample shape: oxide; measurement time: long; environment: vacuum).

-Drying step-

After the above mixing step, a drying step may be performed as needed.

In the drying step, the dispersion medium is removed from the slurry obtained in the mixing step and dried dry. The method of drying the slurry is not particularly limited as long as the solvent used during mixing can be removed, and examples include drying under reduced pressure and drying under heating. Furthermore, the slurry may be dried directly, or it may be dried after filtration.

Furthermore, it is also possible to dry pulverize the dried product of the mixture.

-Calcination step-

Next, the calcination step will be described.

In the calcination step, the raw material mixture obtained by the mixing step (or a dried product obtained by the drying step) is calcined. Thereby, a composite body that is particularly suitable as an abrasive material can be obtained better. In the calcining step, the raw material mixture can be calcined directly, or it can be shaped into a specific shape (for example, pellets) and then calcined. The calcination environment is not particularly limited. The calcination step may be performed only once, or may be performed two or more times.

The calcination temperature in the above calcination step may be a temperature sufficient for the reaction between the strontium compound and the zirconium compound. For example, it is preferably 700 to 1500°C. If the calcination temperature is within this range, the reaction proceeds more fully, and if the calcination temperature is 1500°C or less, the polishing rate of the obtained abrasive material is further improved. The lower limit is more preferably 730°C or higher, still more preferably 750°C or higher, and the upper limit is more preferably 1300°C or lower, still more preferably 1270°C or lower, and particularly preferably 1250°C or lower. Furthermore, especially when a compound other than zirconia is used as the zirconium compound, it is particularly preferable to increase the calcination temperature, for example, preferably 800°C or higher, more preferably 850°C or higher, still more preferably 900°C or higher, and further Preferably it is 930°C or higher.

In this specification, the calcination temperature in the calcination step means the highest temperature reached in the calcination step.

The holding time at the above-mentioned calcination temperature may be sufficient time for the reaction between the strontium compound and the zirconium compound. For example, it is preferably 5 minutes to 24 hours. If hold time Within this range, the reaction proceeds more fully, and if the holding time is 24 hours or less, the generated calcined product (strontium zirconate) is sufficiently suppressed from violently sintering, so the polishing rate can be further increased. It is more preferably 7 minutes to 22 hours, and still more preferably 10 minutes to 20 hours.

In the above-mentioned calcination step, it is preferable to set the temperature increase rate until the maximum temperature (calcination temperature) is increased to 0.2-15°C/min. If the heating rate is 0.2°C/min or more, the time required for heating will not be too long, so the waste of energy and time can be sufficiently suppressed, and if it is 15°C/min or less, the temperature of the furnace contents can be sufficient Follow the set temperature to more fully suppress uneven firing. It is more preferably 0.5 to 12°C/min, and still more preferably 1.0 to 10°C/min.

-Smashing step-

After the above-mentioned calcination step, a pulverization step can also be performed as needed.

In the pulverization step, the calcined product obtained by the calcination step is pulverized. The pulverization method and pulverization conditions are not particularly limited, and for example, a ball mill, a crusher, a hammer mill, a jet mill, etc. can be used.

〔Method for manufacturing negatively charged substrate with high surface smoothness〕

The method of manufacturing a negatively charged substrate with high surface smoothness as the second aspect of the present invention will be described.

The manufacturing method of the negatively charged substrate with high surface smoothness of the present invention uses the above-mentioned polishing method of the negatively charged substrate of the present invention. That is, each of the manufacturing methods includes at least one polishing step a of polishing a negatively charged substrate in the presence of the polishing material slurry and under the condition that the zeta potential of the polishing material slurry becomes positive, and the polishing step a of polishing the polishing material slurry The polishing step b of polishing a negatively charged substrate under the condition that the zeta potential of the polishing material slurry becomes negative, and the polishing material slurry contains the composition formula: ABO3 (A means selected from Sr and Ca At least one element in the group consisting of. B represents at least one element selected from the group consisting of Ti, Zr and Hf) represented by oxide and oxidation zirconium. If this manufacturing method is used, a higher polishing speed and excellent surface smoothness can be achieved, and therefore, a negatively charged substrate with high surface smoothness can be provided with good productivity.

Example

In order to describe the present invention in detail, examples are listed below, but the present invention is not limited to these examples.

Production example 1 (production of abrasive material A)

(1) Zr raw material preparation steps

While stirring, 3.0 kg of zirconium oxychloride octahydrate (manufactured by Showa Chemical Co., Ltd.) was dissolved in 6.7 L of ion exchange water. The solution was adjusted to 25°C while stirring, and while maintaining the temperature, 180 g/L of sodium hydroxide aqueous solution was added over 1 hour while stirring until the pH value became 9.5, and then stirred for 1 hour. The slurry was filtered and washed with water, and washed with water until the conductivity of the washing liquid became 100 μS/cm or less, thereby obtaining a zirconium hydroxide block.

500 g of the zirconium hydroxide agglomerate was sufficiently dried at a temperature of 120°C. Next, 40 g of the obtained dried product was put into an alumina crucible with an outer diameter of 55 mm and a volume of 60 mL, and calcined in an electric furnace (manufactured by ADVANTEC Corporation, KM-420) to obtain zirconia. The calcination conditions were heating from room temperature to 800°C over 240 minutes, maintaining at 800°C for 300 minutes, and then stopping energizing the heater and cooling to room temperature. Furthermore, calcination is performed in the atmosphere.

(2) Mixing steps

之氧化鋯珠415g，使用塗料調節器(RED DEVIL公司製造：5110型)混合30分鐘。 Weigh 26.1 g of strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd.: SW-PN) as Sr raw material and 31.3 g of zirconia obtained by the above (1) Zr raw material preparation step as Zr raw material into 300 mL of egg yolk In the sauce bottle, add 172mL and 1mm ion exchange water

415 g of the zirconia beads were mixed for 30 minutes using a paint conditioner (manufactured by RED DEVIL: Model 5110).

(3) Drying step

The slurry obtained by the mixing step (2) above was passed through a 400 mesh (38μm mesh) sieve to remove the zirconia beads, and then the agglomerates of the mixture obtained by filtration were heated to 120°C Fully dry, thereby obtaining a dried product of the mixture.

(4) Calcining step

Put 30 g of the dried product of the mixture obtained in the above (3) drying step into an alumina crucible with an outer diameter of 55 mm and a capacity of 60 mL, and calcined using an electric furnace (manufactured by ADVANTEC, KM-420) , And obtain the calcined product. The calcination conditions were heating from room temperature to 950°C in 285 minutes, maintaining at 950°C for 180 minutes, and then stopping energizing the heater and cooling to room temperature. Furthermore, calcination is performed in the atmosphere.

(5) Crushing step

Add 10 g of the calcined product obtained by the above-mentioned (4) calcining step into an automatic mortar (battering machine) (manufactured by Nichito Scientific Co., Ltd.: ANM-150) and pulverize for 10 minutes to obtain SrZrO ₃ Abrasive material composed of composite with ZrO ₂ . It is also called "abrasive material A".

<Performance evaluation of abrasive materials and Zr materials used>

According to the methods described in (i) to (vi) below, various physical properties of the abrasive material obtained in Production Example 1 and the Zr raw material (zirconia) used in Production Example 1 were evaluated.

(i) Measurement of powder X-ray diffraction

The powder X-ray diffraction patterns (also referred to as X-ray diffraction patterns) of the Zr raw material (zirconia) and the abrasive material were respectively measured under the following conditions.

Machine used: RINT-Ultima III manufactured by RIGAKU Co., Ltd.

Radioactive source: CuK α

Voltage: 40kV

Current: 40mA

Sample rotation speed: no rotation

Divergence slit: 1.00mm

Divergence longitudinal restriction slit: 10mm

Scattering slit: open

Light receiving slit: open

Scan mode: FT

Counting time: 2.0 seconds

Step width: 0.0200°

Operating axis: 2 θ/θ

Scan range: 10.0000~70.0000°

Cumulative times: 1 time

Monoclinic ZrO ₂ : JCPDS card 00-037-1484

Square crystal ZrO ₂ : JCPDS card 00-050-1089

Cubic ZrO ₂ : JCPDS card 00-049-1642

Rhombic SrZrO ₃ : JCPDS card 00-044-0161

Rhombic CaZrO ₃ : JCPDS card 00-035-0645

The X-ray diffraction pattern of the Zr raw material used in Manufacturing Example 1 is shown in FIG. 1, and the X-ray diffraction pattern of the obtained abrasive material is shown in FIG. 2.

It can be seen that the X-ray diffraction pattern of the abrasive material shown in FIG. 2 includes both the peaks of ZrO ₂ and SrZrO _{3 in} the known database (JCPDS card) of peak positions. Therefore, the abrasive obtained in Production Example 1 has a crystal phase of SrZrO ₃ and a crystal phase of ZrO ₂ .

(ii) Measurement of half-width

According to the diffraction pattern obtained by the measurement of the X-ray diffraction of the Zr raw material, the half-height width of the maximum peak of ZrO ₂ at 2 θ=27.00~31.00° is measured. According to the X-ray diffraction of the abrasive material The obtained diffraction pattern was measured to measure the Rhombic SrZrO ₃ (040) FWHM. The results are shown in Table 1.

Furthermore, in X-ray diffraction using CuK α rays as the radiation source, the largest peak of monoclinic ZrO ₂ originated from the (-111) plane is located near 2 θ=28.14°, which is regarded as tetragonal ZrO ₂ The largest wave peak of ZrO ₂ is derived from the (011) plane and the peak is located near 2 θ=30.15°. The largest wave peak of cubic ZrO ₂ is derived from the (111) plane and the peak is located near 2 θ=30.12°, which is derived from orthorhombic crystals. The crest of the (040) plane of SrZrO ₃ is located near 2 θ=44.04°, and the crest of the (121) plane derived from orthorhombic CaZrO ₃ is located near 2 θ=31.5°.

As shown in Figure 1, in the X-ray diffraction pattern of the Zr raw material (zirconia) used in Manufacturing Example 1, the peak originating from the (-111) plane of monoclinic ZrO _{2 was} confirmed to be at 2 θ= The FWHM of the maximum peak of 27.00~31.00° is 0.38°.

As shown in FIG. 2, in the X-ray diffraction pattern of the abrasive material obtained in Manufacturing Example 1, it was confirmed that the peak originated from the (040) plane of orthorhombic SrZrO ₃ , and its half-height width was 0.33°.

(iii) Determination of specific surface area

The measurement of the specific surface area of the Zr raw material and the abrasive material was carried out under the following conditions. The results are shown in Table 1.

Machine used: Macsorb Model HM-1220 made by Mountech

Environment: Nitrogen (N ₂ )

Degassing conditions of external degassing device: 200℃-15 minutes

Degassing conditions of the specific surface area measuring device body: 200℃-5 minutes

(iv) Measurement of electron microscope images

A scanning electron microscope (SEM) (manufactured by JEOL Co., Ltd.: model JSM-6510A) was used to take SEM images of the abrasive material. The SEM image of the abrasive material obtained in Manufacturing Example 1 is shown in FIG. 3.

As shown in FIG. 3, the abrasive material obtained in Manufacturing Example 1 forms indefinite secondary particles in which a plurality of primary particles are randomly assembled.

(v) Elemental analysis

The element analysis of the abrasive material is carried out by the EZ scan with the element scanning function of the fluorescent X-ray analysis device (manufactured by RIGAKU Co., Ltd.: model ZSX Primus II). Place the stamped sample on the measurement sample table, select the following conditions (measurement range: FU; measurement diameter: 30mm; sample form: oxide; measurement time: long; environment: vacuum) to determine the Sr content (SrO conversion) ) And Ca content (calculated as CaO). The results are shown in Table 1.

(vi) Sharpness of particle size distribution (D ₉₀ /D ₁₀ )

A laser diffraction-scattering particle size analyzer (manufactured by Nikkiso Co., Ltd.: Model Microtrac MT3300EX) was used to measure the particle size distribution of the abrasive material.

First, 60 mL of ion-exchanged water was added to 0.1 g of the abrasive, and it was stirred sufficiently at room temperature using a glass rod to prepare a suspension of the abrasive. Furthermore, no dispersion operation using ultrasound was performed. After that, prepare 180 mL of ion-exchanged water and pour it into the sample circulator, and add the above suspension dropwise so that the penetration rate becomes 0.71 to 0.94, while the flow rate is 50% without ultrasonic dispersion. The measurement is performed on the cycle side.

Manufacturing example 2 (abrasive material B)

Using 31.3 g of zirconium hydroxide mass obtained by "(1) Zr raw material preparation step" in ZrO ₂ conversion as the Zr raw material in "(2) Mixing step" of Production Example 1, in addition to In the same manner as in Production Example 1, an abrasive material B composed of a composite of SrZrO ₃ and ZrO ₂ was obtained.

Measure or evaluate the half-height width, specific surface area, element analysis, and sharpness of particle size distribution of the abrasive B in the same manner as in Production Example 1, and also measure Zr used in Production Example 2 in the same manner as in Production Example 1. The specific surface area of the raw material (zirconium hydroxide). The results are shown in Table 1.

Manufacturing example 3 (abrasive material E)

22.5 g of calcium carbonate (manufactured by Sakai Chemical Industry Co., Ltd.: CWS-20) was used as the Ca raw material in the "(2) mixing step" of Production Example 1, and the preparation step of the "(1) Zr raw material" in Production Example 1 was used "42.4 g of the obtained zirconium oxide was used as a Zr raw material, except that the abrasive material E composed of a composite of CaZrO ₃ and ZrO ₂ was obtained in the same manner as in Production Example 1.

The half-height width, specific surface area, element analysis, and sharpness of particle size distribution of the abrasive E were measured or evaluated in the same manner as in Production Example 1. The results are shown in Table 1.

Production example 4 (abrasive slurry A)

The polishing material slurry A was produced using the polishing material A produced in Production Example 1.

Specifically, 20.0 g of the abrasive A was dispersed in 380.0 g of ion-exchange water, and stirred at 25°C for 10 minutes. Thus, abrasive slurry A was obtained.

The zeta potential of the polishing material slurry A was measured under the following conditions. The relationship of the zeta potential with respect to the pH value of the polishing material slurry is shown in FIG. 4. In addition, the isoelectric point of the abrasive slurry A was 6.4. Here, the isoelectric point refers to the point at which the algebraic sum of the charge of the abrasive particles (abrasive material) in the abrasive slurry is zero, that is, the point where the positive and negative charges of the abrasive particles become equal. Use the pH value of the abrasive slurry at this point to indicate.

<Measurement conditions of zeta potential>

Measuring instrument: manufactured by Otsuka Electronics Co., Ltd., zeta potential measuring system, model ELSZ-1

pH titrator: manufactured by Otsuka Electronics Co., Ltd., model ELS-PT

Dilute 6 g of the abrasive slurry 5 times with ion-exchanged water, stir it with a glass rod and disperse it with an ultrasonic cleaner for 1 minute. To 10 cc of this slurry, 50 cc of ion-exchanged water was added, and an ultrasonic homogenizer (US-600, manufactured by Nippon Seiki Seisakusho, Ltd.) was used, and the intensity was set to V-LEVEL3 to perform dispersion treatment for 1 minute. 30 cc of the polishing material slurry for zeta potential measurement thus obtained was filled in a zeta potential measuring instrument.

In addition, the abrasive slurry D using colloidal silica described later uses an ultrasonic homogenizer (US-600, manufactured by Nippon Seiki Seisakusho), and the strength is set to V-LEVEL3 for the abrasive slurry D 60cc for 1 minute Disperse processing. 30 cc of the polishing material slurry for zeta potential measurement thus obtained was filled in a zeta potential measuring instrument.

Furthermore, in order to adjust the pH of the abrasive slurry, use the following pH as needed Value adjuster.

PH adjustment solution for acidic side: aqueous hydrochloric acid, 0.1mol/L

Alkaline side pH adjustment solution: sodium hydroxide aqueous solution, 1mol/L

Manufacturing example 5 (abrasive material slurry B)

An abrasive slurry B was produced in the same manner as in Production Example 4 (abrasive slurry A) except that the abrasive B produced in Production Example 2 was used.

The zeta potential of the polishing material slurry B was measured under the above-mentioned measurement conditions. The relationship of the zeta potential with respect to the pH value of the polishing material slurry is shown in FIG. 4. In addition, the isoelectric point of the abrasive slurry B was 6.2.

Production example 6 (abrasive material slurry C)

Except for using a cerium oxide abrasive for glass polishing (manufactured by Showa Denko Co., Ltd., SHOROX(R)A-10, cerium oxide content: 60% by weight, isoelectric point: 10.4) as the abrasive, the same as in Manufacturing Example 4 The abrasive slurry C is made in the same way. The relationship of the zeta potential with respect to the pH value of the polishing material slurry is shown in FIG. 4.

Manufacturing example 7 (abrasive slurry D)

52.2 g of colloidal silica (Fuso Chemical Industry Co., Ltd., Quartron(R) PL-7, isoelectric point: 5.8) was dispersed in 347.8 g of ion-exchange water, and stirred at 25°C for 10 minutes. This was used as the abrasive slurry D. The relationship of the zeta potential with respect to the pH value of the polishing material slurry is shown in FIG. 4.

Manufacturing example 8 (abrasive material slurry E)

The polishing material slurry E was produced in the same manner as in Production Example 4 (abrasive material slurry A) except that the polishing material E produced in Production Example 3 was used.

The zeta potential of the polishing material slurry E was measured under the above-mentioned measurement conditions. The relationship of the zeta potential with respect to the pH value of the polishing material slurry is shown in FIG. 4. The isoelectric point of the abrasive slurry E is 6.1.

Example 1

(1) The first grinding step

After adjusting the pH value of the slurry so that the zeta potential of the polishing material slurry A obtained in Production Example 4 was changed to the value shown in Table 2, in the presence of the slurry, the glass was processed under the following polishing conditions Grinding of the substrate. The pH value of the abrasive slurry A in this step is shown in Table 2. In addition, the polishing rate in the first polishing step and the surface roughness of the glass substrate after the first polishing step were evaluated according to the following method. The results are shown in Table 2.

(2) The second grinding step

Directly and continuously use the abrasive slurry A used in the above-mentioned first polishing step, adjust the pH of the slurry so that its zeta potential becomes the value shown in Table 2, and then in the presence of the slurry, Polish the glass substrate under the same polishing conditions as the first polishing step. The pH value of the abrasive slurry A in this step is shown in Table 2. In addition, the polishing rate in the second polishing step and the surface roughness of the glass substrate after the second polishing step were evaluated according to the following method. The results are shown in Table 2.

<Grinding conditions>

Glass plate used: soda lime glass (manufactured by Songlang Glass Industry Co., Ltd., size 36×36×1.3mm, specific gravity 2.5g/cm ³ )

) Grinding machine: desktop grinding machine (made by MAT Co., Ltd., MAT BC-15C, grinding platen diameter 300mm

)

Grinding pad: foamed polyurethane pad (manufactured by Nitta Haas Co., Ltd., MHN-15A, no Impregnated cerium oxide (ceria))

Grinding pressure: 101g/cm ²

Rotation of pressure plate: 70rpm

Supply volume of abrasive slurry: 100mL/min

Grinding time: 60min

<Measurement of Grinding Speed>

Use an electronic balance to measure the weight of the glass substrate before and after each grinding step. Calculate the thickness reduction of the glass substrate based on the weight reduction, the area of the glass substrate and the specific gravity of the glass substrate, and then calculate the polishing speed (μm/min).

Grind 3 glass substrates at the same time, and replace the glass substrate and polishing material slurry after 60 minutes of grinding. This operation was performed 3 times, and the average value of the polishing rate of a total of 9 sheets was taken as the value of the polishing rate of each Example and Comparative Example.

<Measurement of the surface smoothness of the glass substrate>

The surface roughness of the glass substrate after each polishing step is measured under the following conditions.

Measuring instrument: manufactured by ZYGO Co., Ltd., white interference microscope, model NewView ^TM 7100

Horizontal resolution: <0.1nm

Objective lens: 50 times

Filter: None

Measuring field size: X=186μm, Y=139μm

Evaluation method: For the polished glass substrate, measure the central point and the intersection of a concentric circle with a radius of 6mm and 12mm from the central point and the diagonal line of the glass substrate, a total of 9 points Ra, and calculate it average value. This operation was performed on a total of 9 glass substrates used in the measurement of the above-mentioned polishing rate, and the average value of Ra of each glass substrate was used for averaging to evaluate the surface roughness.

Example 2

After the first polishing step, take out the polishing material slurry A, switch to the new polishing material slurry A (in which the pH value of the slurry is adjusted to the value shown in Table 2), and proceed to the second polishing step. The first polishing step and the second polishing step were performed in the same manner as in Example 1. Table 2 shows the pH value, zeta potential, polishing rate, and surface roughness of the glass substrate of the abrasive slurry in each step.

Example 3

Except for using the abrasive slurry B instead of the abrasive slurry A, the first polishing step and the second polishing step were performed in the same manner as in Example 2. Table 2 shows the pH value, zeta potential, polishing rate, and surface roughness of the glass substrate of the abrasive slurry in each step.

Example 4

Except for using the abrasive slurry E instead of the abrasive slurry A, the first polishing step and the second polishing step were performed in the same manner as in Example 2. Table 2 shows the pH value, zeta potential, polishing rate, and surface roughness of the glass substrate of the abrasive slurry in each step.

Comparative example 1

(1) The first grinding step

After adjusting the pH value of the slurry in such a way that the zeta potential of the abrasive slurry C obtained in Production Example 6 was changed to the value shown in Table 2, the slurry was subjected to the same polishing method as in Example 1 in the presence of the slurry Condition to grind the glass substrate. Table 2 shows the pH value of the abrasive slurry C in this step. In addition, the polishing rate in the first polishing step and the surface roughness of the glass substrate after the first polishing step were evaluated according to the above-mentioned method. The results are shown in Table 2.

(2) The second grinding step

The abrasive slurry C used in the above-mentioned first polishing step is taken out of the grinder, and the grinder is cleaned. After adjusting the pH value so that the zeta potential of the separately prepared abrasive slurry D becomes the value shown in Table 2, the glass is processed under the same polishing conditions as the first polishing step in the presence of the abrasive slurry D Grinding of the substrate. Table 2 shows the pH value of the abrasive slurry D in this step. In addition, the polishing rate in the second polishing step and the surface roughness of the glass substrate after the second polishing step were evaluated according to the above-mentioned method. The results are shown in Table 2.

The following contents were confirmed from the above-mentioned Examples and Comparative Examples.

In Examples 1 and 2 and Comparative Example 1, although the surface roughness of the finally obtained substrate (the substrate after the second polishing step) was approximately the same, the polishing speed of Examples 1 and 2 was significantly higher than that of Comparative Example 1. . From the comparison of Examples 3 and 4 and Comparative Example 1, it can be confirmed that they are substantially the same situation. Therefore, it can be seen that the polishing method of the negatively charged substrate of the present invention can achieve a higher polishing speed and excellent surface smoothness in a cerium-free polishing material. In addition, in Comparative Example 1, cerium oxide-based abrasives were used in the first polishing step, and colloidal silica was used in the second polishing step. Therefore, cleaning operations of the polishing machine were necessary. In Examples 1 to 4, The same type of abrasive slurry is used in the first polishing step and the second polishing step, so there is no need for cleaning operations of the grinder, etc., which is very advantageous in terms of work and equipment.

Furthermore, it can be seen that the polishing material slurry A used in the first polishing step was directly and continuously used in the second polishing step of Example 1. In contrast, the second polishing step of Example 2 used the same as that used in the first polishing step. The polishing material slurry A used in the polishing step is the same, but the new polishing material slurry A is used for polishing. In this respect, there is a difference between Example 1 and Example 2. However, this difference has little effect on the polishing speed and the surface smoothness of the obtained substrate.

1‧‧‧Grinding material A

2‧‧‧Glass

3‧‧‧Lapping Pad

Claims (10)

A method for polishing a negatively charged substrate, which is a method of polishing a negatively charged substrate using an abrasive slurry, characterized in that: the abrasive slurry contains a composition formula: ABO ₃ (A represents selected from Sr and Ca At least one element in the group, B represents at least one element selected from the group consisting of Ti, Zr, and Hf) and zirconia represented by the oxide and zirconium oxide, and the polishing method is performed at least once each on the polishing material The polishing step a of polishing the negatively charged substrate under the condition that the zeta potential of the slurry becomes positive, and the polishing step b of polishing the negatively charged substrate under the condition that the zeta potential of the polishing material slurry becomes negative. For example, the polishing method for negatively charged substrates in the scope of the patent application, wherein the above-mentioned oxide is SrZrO ₃ and/or CaZrO ₃ . For example, the polishing method for negatively charged substrates in the scope of the patent application, wherein the pH value of the polishing material slurry is greater than the isoelectric point of the above-mentioned negatively charged substrate and does not reach the condition of the isoelectric point of the polishing material slurry Next, the above-mentioned grinding step a is implemented. For example, the second item of the scope of patent application for the polishing method of a negatively charged substrate, wherein the pH value of the polishing material slurry is greater than the isoelectric point of the above-mentioned negatively charged substrate and does not reach the condition of the isoelectric point of the polishing material slurry Next, the above-mentioned grinding step a is implemented. For example, the method for polishing a negatively charged substrate in any one of items 1 to 4 of the scope of patent application, wherein the pH of the polishing material slurry is greater than the isoelectric point of the polishing material slurry and becomes 13 or less, Perform the above-mentioned grinding step b. For example, the method for polishing a negatively charged substrate according to any one of items 1 to 4 in the scope of the patent application, wherein the negatively charged substrate is a glass substrate. For example, the method for polishing a negatively charged substrate according to the fifth item of the scope of patent application, wherein the negatively charged substrate is a glass substrate. For example, the polishing method for negatively charged substrates in any one of items 1 to 4 of the scope of patent application, wherein the D ₉₀ /D ₁₀ of the above-mentioned polishing material is 1.5-50. For example, the polishing method for negatively charged substrates in any one of items 1 to 4 in the scope of patent application, wherein the specific surface area of the above-mentioned polishing material is 1.0-50m ² /g. A method for manufacturing a negatively charged substrate with high surface smoothness, which uses the polishing method of any one of the 1 to 9 patent applications.

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