JP2005205542A - Sapphire polishing grinding wheel and sapphire polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single crystal sapphire polishing grinding wheel and a single crystal sapphire polishing method, having high polishing efficiency, and capable of providing superior surface roughness. <P>SOLUTION: This polishing grinding wheel can provide both high polishing efficiency and superior surface roughness, when polishing a single crystal sapphire substrate, due to being constituted by joining a fine abrasive grain having an average particle size of about 0.6 μm, composed of α-based alumina manufactured from alcoholate by using a sol-gel method, by an epoxy resin binder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing wheel for final polishing single crystal sapphire and a method for final polishing single crystal sapphire.

  Single crystal sapphire is excellent in mechanical properties, chemical stability, translucency, etc., so that one surface (for example, both surfaces in a substrate) is polished to a so-called mirror surface, so that semiconductor materials and optical components Etc. are suitably used. Conventionally, when a substrate made of single crystal sapphire is mirror-finished, loose abrasive processing using silica-based abrasive grains has been performed (see, for example, Patent Document 1).

In addition, it has been proposed to use a grindstone composed only of a sintered body of inorganic abrasive grains instead of the above-mentioned free abrasive grain processing (see, for example, Patent Document 2). As the inorganic abrasive grains, various kinds such as diamond abrasive grains, boron carbide abrasive grains, cubic boron nitride abrasive grains, and the like are used.
JP-A-8-95233 Japanese Patent Laid-Open No. 10-337669

  However, the loose abrasive polishing described in Patent Document 1 is a wet process using colloidal silica (silicone emulsion) as an abrasive, and although a good surface roughness can be obtained, the polishing efficiency (that is, per unit time). There was a disadvantage that the removal amount was low. Further, according to the finish polishing grindstone described in Patent Document 2, for example, even better surface roughness of about 3 (nm) in Ra can be obtained, but there is a disadvantage that the polishing efficiency is extremely low.

  The present invention has been made in the background of the above circumstances, and the object thereof is a single crystal sapphire polishing grindstone and a single crystal sapphire polishing method capable of obtaining high polishing efficiency and good surface roughness. Is to provide.

  Under the above objective, the present inventors prepared various abrasive grains that could be used for final polishing of single crystal sapphire and conducted a wet loose abrasive processing test. The test objects selected were cerium oxide, mica, silica, alumina, aluminum hydroxide, calcium fluoride, and colloidal silica that is usually used. As a result, surprisingly, alumina showed the best polishing efficiency among them. In response to this result, various alumina abrasive grains were further evaluated. In order for the α-type alumina produced by the sol-gel method using alcoholate as a starting material to achieve both polishing efficiency and surface roughness in sapphire polishing. It turned out to be most preferable. The reason why such a result was obtained is presumed to be because the surface activity of α-type alumina produced by the above production method is high. The present invention has been made based on such research results.

  The gist of the first invention for achieving the above object is to have a polished surface in which abrasive grains are bonded with a predetermined binder, and one surface of the single crystal sapphire has a predetermined surface roughness on the polished surface. A sapphire polishing grindstone for finish polishing, wherein (a) the abrasive grains are made of α-type alumina produced by using a sol-gel method using alcoholate as a starting material.

  The gist of the second invention for achieving the above object is a sapphire polishing method for finishing and polishing one surface of single-crystal sapphire to a predetermined surface roughness, starting from (a) alcoholate Polishing is carried out while supplying abrasive grains made of α-type alumina produced using a sol-gel method as a raw material to the one surface.

  In this way, the abrasive grains used in the sapphire polishing grindstone and the abrasive grains used in the sapphire polishing method are α-type alumina, that is, hexagonal aluminum oxide produced from alcoholate using a sol-gel method. Therefore, when polishing single crystal sapphire, both high polishing efficiency and good surface roughness can be obtained.

  Note that alcoholate is a general term for compounds in which hydrogen of the hydroxy group of alcohol is substituted with a metal element, and is also referred to as alkoxide or metal alkoxide. The alcoholate that can be used in the present invention is not particularly limited, and alcoholates having various hydroxy groups can be used as starting materials for the abrasive grains.

  Here, preferably, in the polishing wheel and the polishing method, the abrasive grains have an average particle diameter of 5 (μm) or less. In this case, since abrasive grains having a sufficiently small average particle diameter are used, surface scratches due to the abrasive grains are hardly generated, so that even better surface roughness can be obtained. In addition, the smaller the average particle size, the greater the specific surface area and the more prominent the chemical action, which has the advantage of improving the polishing efficiency. More preferably, the average particle diameter of the abrasive grains is 0.01 (μm) or more. In this way, since sufficiently large abrasive grains are used, higher polishing efficiency can be obtained. That is, if it is less than 0.01 (μm), a good polished surface can be obtained, but the polishing efficiency is lowered. Therefore, the average particle size of the abrasive grains is preferably in the range of 0.01 to 5 (μm). More preferably, the average particle size of the abrasive grains is in the range of 0.1 to 3 (μm).

  Preferably, in the polishing grindstone, the binder is a synthetic resin binder. The binder is not limited to a synthetic resin binder, and may be a glassy binder or a metallic binder, but in this way, a synthetic resin bond having a relatively low elastic modulus, that is, elastically deformed easily. Since the abrasive grains are bonded with the agent, when the pressing force is applied from the surface to be polished of single crystal sapphire, it is easily retracted from the surface to be polished. For this reason, it is suitably suppressed that the surface to be polished is scratched, and a higher quality surface to be polished can be obtained.

  More preferably, the binder is a thermosetting resin, and more preferably a liquid epoxy resin is used. In order to obtain a high flatness of the surface to be polished, it is desirable that the polished surface shape of the polishing wheel be maintained during processing, but since epoxy resin has an appropriate elastic modulus, surface roughness and flatness It is suitable for achieving both. In particular, when a liquid epoxy resin is used, since the abrasive grains mixed therein are dispersed with high uniformity, a polishing wheel with high uniformity of the structure in which the abrasive grains are uniformly dispersed is obtained. Further excellent surface roughness, flatness, etc. can be obtained.

  Preferably, the polishing method uses a polishing grindstone in which the abrasive grains are bonded with a binder. In this way, the abrasive fixed type processing using a polishing grindstone or the like is less likely to cause sagging of the surface to be polished (the shape in which the outer peripheral edge is excessively removed) compared to free abrasive processing, Since processing waste liquid is reduced, there is an advantage over the environment.

  Further, the present invention is applied to a polishing grindstone and a polishing method for polishing one surface of single crystal sapphire, and is particularly preferably applied to finish polishing and also preferably applied to mirror polishing of a sapphire substrate. .

  Preferably, the polishing grindstone is a grindstone layer having a predetermined thickness dimension fixed to the upper surface of a disk-shaped base plate provided with an attachment hole penetrating in the thickness direction at the axial center. The present invention can be applied to a polishing grindstone and a polishing method used in various polishing apparatuses, but is particularly preferably applied to such a polishing grindstone used in a single-side polishing machine and a polishing method using the same.

  The base plate is made of, for example, an aluminum alloy, but may be made of steel, resin, or the like.

  Further, preferably, the above-described polishing grindstone is provided with a number of grooves in the grindstone layer from the polishing surface toward the base plate. Such grooves are not essential, but if a large number of grooves are formed, the ridges of the grooves provided on the polishing surface suitably contribute to improving the polishing efficiency, and the grooves can be used as machining fluid, cutting powder, etc. It functions suitably as a discharge path.

  Preferably, the polishing grindstone includes the abrasive grains at an abrasive grain ratio within a range of 10 to 60 (%). In this way, the number of abrasive grains contributing to the working surface is increased and a balance with the amount of binder is obtained, so that a high polishing efficiency can be obtained. Note that when the abrasive grain ratio exceeds 60 (%), the ratio of the binder becomes remarkably low, so that there is an inconvenience that the grinding wheel holding force becomes insufficient and the grinding wheel wear becomes remarkable, and the life of the grinding wheel is shortened. is there.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a perspective view showing an entire sapphire polishing grindstone (hereinafter simply referred to as a polishing grindstone) 10 according to an embodiment of the present invention. In the figure, a grinding wheel 10 is configured by a similar shaped grinding wheel layer 16 being fixed to one surface of a disk-shaped base plate 14 having a mounting hole 12 penetrating in the thickness direction at the center. . This grinding wheel 10 is used by being attached to the rotating shaft of a single-sided (one-sided) lapping machine in the mounting hole 12 in a direction in which the grinding wheel layer 16 is positioned on the upper side.

  The base plate 14 is made of a metal material such as an aluminum alloy, for example, and has a size of, for example, an outer diameter of 327 (mm) × inner diameter of 110 (mm) × thickness of 20 (mm). . The surface of the base plate 14 is processed flat, and the grindstone layer 16 is fixed to the flat surface using an adhesive such as an epoxy resin.

  Further, the grindstone layer 16 is, for example, one in which abrasive grains are bound by a binder such as synthetic resin, and has, for example, an outer diameter dimension and an inner diameter dimension similar to those of the base plate 14, and is about 10 (mm). It has a thickness dimension. The grindstone layer 16 has a structure having an abrasive grain ratio Vg of about 40 (volume%), a binder ratio Vb of about 15 (volume%), and a porosity Vp of about 45 (volume%). The abrasive grains are dispersed substantially uniformly. Further, on the surface of the grindstone layer 16, that is, the polished surface 18, a large number of grooves 20 having a depth similar to or slightly shallower than the thickness of the grindstone layer 16 are formed in a lattice shape, for example. The width dimension of the groove 20 is, for example, about 2 (mm), and the center interval is, for example, about 15 (mm).

The abrasive grains have an average particle size in the range of 0.1 to 5 (μm), for example, about 0.6 (μm), and the specific surface area in the range of 1 to 200 (m ² / g), for example, 5.9 (m ² / g ) Grade α-type alumina. The abrasive grains are produced, for example, by a sol-gel method using aluminum alkoxide as a starting material. The binder is, for example, an epoxy resin.

  Such a grinding wheel 10 is manufactured by, for example, mixing the above-mentioned abrasive grains in a liquid epoxy resin and stirring them substantially uniformly to disperse them, and curing them in a mold to produce the grinding wheel layer 16. It is manufactured by bonding to the base plate 14 after processing for adjusting the size and shape as necessary.

  FIG. 2 schematically shows a state in which the polishing grindstone 10 is used and is attached to the single-sided lapping machine 22. In FIG. 2, the grinding wheel 10 is attached to a rotation shaft (not shown) so as to be rotatable around its axis in the mounting hole 12 in a direction in which the grinding wheel layer 16 is positioned on the upper side, and is held by a carrier 24. Thus, the movement of the polishing wheel 10 in the circumferential direction is suppressed, and workpieces pressed against the upper surface, that is, the polishing surface with a certain load, are arranged at, for example, three locations on the upper surface. In addition, a nozzle 26 is provided above the polishing wheel 10 so that a polishing liquid such as water is supplied toward the polishing surface. The lapping machine 22 is provided with an arm or the like for keeping the carrier 24 at a fixed position, but this is omitted in FIG.

3 and 4 show a case where a single crystal sapphire substrate having a size of about φ2 (inch) is finished and polished with a polishing grindstone 10 (hereinafter referred to as Example 1) using the lapping machine 22 as described above. The results of evaluating the polishing efficiency were compared with Examples 2 and 3 using other abrasive grains, conventional free abrasive processing (Comparative Example 1), and processing with a polishing grindstone using abrasive grains made of other materials (Comparative Example) It is a figure shown in comparison with 2,3). In Example 2, alumina abrasive grains having an average particle diameter of about 0.6 (μm) and a specific surface area of about 4.8 (m ² / g) were used, and the abrasive grain ratio Vg was about 30.5 (volume%). The polishing wheel 10 is configured in substantially the same manner except that Vb is about 16.7 (volume%) and the porosity Vp is about 52.8 (volume%). In Example 3, alumina abrasive grains having an average particle diameter of about 0.4 (μm) and a specific surface area of about 4.9 (m ² / g) are used, and the abrasive grain ratio Vg is about 28,9 (volume%). Except for the fact that the agent rate Vb is about 15.9 (volume%) and the porosity Vp is about 55.2 (volume%), it is configured in substantially the same manner as the grinding wheel 10 for polishing. The abrasive grains used in Examples 2 and 3 are each α-type alumina produced by a sol-gel method using aluminum alkoxide as a starting material.

  In Comparative Example 1, a pad (for example, IC1000 manufactured by Rodel Nitta Co., Ltd.) is used in place of the polishing grindstone 10, and a slurry containing silica-based abrasive grains (for example, Compole EX-3 manufactured by Fujimi Incorporated) is used. Is supplied and polished. The pad is a urethane foam porous body. Further, in Comparative Example 2, silica abrasive grains (for example, manufactured by Tatsumori Co., Ltd.) having an average particle diameter of about 1.0 (μm) instead of alumina abrasive grains are bonded with a soft bond degree. It is constituted similarly. Further, Comparative Example 3 is configured in the same manner as the polishing grindstone 10 except that synthetic mica (mica) (for example, manufactured by Co-op Chemical) having an average particle diameter of about 2.0 (μm) is used as the abrasive grains.

Further, in this evaluation test, the single-side lapping machine EJ-380 manufactured by Engis Co., Ltd. was used as the single-sided lapping machine 22, and in either of Examples 1 to 3 and Comparative Examples 1 to 3, the number of rotations of the grinding stone or pad and the workpiece 90 (rpm), the number of workpieces to be simultaneously polished was set to three. The pressing load applied to the polishing surface applied to the workpiece was set to, for example, about 208 (g / cm ² ), and polishing was performed while supplying water as a polishing liquid at a flow rate of 10 (ml / min). As the workpiece, a mirror-polished product and a lapping product were prepared, and the processing times were 60 minutes and 210 minutes, respectively. FIG. 3 shows the processing result of the mirror-polished product, and FIG. 4 shows the processing result of the lapping product (that is, one having a ground glass surface). These were subjected to finish polishing under the same conditions except that the processing time was different. In Examples 2 and 3, only the processing of the mirror polished product was evaluated.

  As shown in FIG. 3 above, when the mirror-finished product is polished, according to the final polishing using the polishing grindstone 10 of Example 1, the cumulative deleted weight is 1.9 (mg in a polishing time of 30 minutes. ), An extremely high polishing efficiency of about 2.8 (mg) was obtained in a polishing time of 60 minutes. This is 1.6 to 1.8 times the value of Comparative Example 1, that is, the conventional polishing with free abrasive grains was about 1.05 (mg) in 30 minutes and about 1.65 (mg) in 60 minutes. . Even after 60 minutes of polishing, the abrasion of the polishing wheel 10 remains only 1 (μm), and the surface roughness of the workpiece surface after processing is about 0.986 (nm) for Ra and about 5.943 (nm) for Rmax. And, it was equal to or more than that in the case of conventional free abrasive processing. Incidentally, in the case of conventional loose abrasive machining, that is, in Comparative Example 1, the surface roughness is about 0.97 (nm) for Ra and about 6.48 (nm) for Rmax.

  Further, in the finish polishing using the polishing wheel of Example 2, the cumulative removal weight has a relatively high polishing efficiency of about 1.05 (mg) with a polishing time of 30 minutes and about 2.2 (mg) with a polishing time of 60 minutes. Obtained. This is about the same value for a polishing time of 30 minutes and about 1.3 times for a polishing time of 60 minutes compared to the conventional loose abrasive processing. Also in Example 2, there was almost no grinding wheel wear after polishing for 60 minutes, and the surface roughness of the workpiece surface was almost the same as in Example 1. In addition, the polishing ability does not decrease with time, but rather the polishing ability tends to improve.

  Further, in the final polishing using the polishing grindstone of Example 3, the cumulative deleted weight shows a relatively high value of about 0.8 (mg) for a polishing time of 30 minutes and about 1.3 (mg) for a polishing time of 60 minutes. It was. This is a result almost equal to that of Comparative Example 1, although it is slightly inferior to Comparative Example 1, and considering that the fixed abrasive processing as in Example 3 is more environmentally friendly than the free abrasive processing. Worth enough to use. In Example 3 as well, there was almost no grinding wheel wear after 60 minutes of polishing, and the surface roughness of the workpiece surface was almost the same as in Examples 1 and 2.

  On the other hand, in Comparative Examples 2 and 3 evaluated simultaneously for the control, even after polishing for 60 minutes, Comparative Example 2 has an extremely low value of about 0.2 (mg), and Comparative Example 3 has about 0.3 (mg). Stayed in. Moreover, the amount of grinding wheel wear was several (μm) in Comparative Example 2 and about 1 (μm) in Comparative Example 3, and it was confirmed that the grinding wheel wear was remarkably large with respect to the polishing efficiency. The polishing wheel of Example 3 has a very high polishing efficiency as compared with Comparative Examples 2 and 3, that is, the conventional polishing wheel.

  Further, as shown in FIG. 4, in the lapping of the lapping product, the accumulated weight after 60 minutes is about 11 (mg) for the grinding stone 10 of Example 1, while that for Comparative Example 1 is 2 (mg), Comparative Example 2 was about 5 (mg), and Comparative Example 3 was almost zero (less than 1 (mg)). That is, it was confirmed that the polishing efficiency was 2 to 10 times or higher as compared with Comparative Examples 1 to 3, as in the polishing of the mirror-finished product. Moreover, the polishing wheel 10 of Example 1 shows almost no decrease in polishing ability (polishing efficiency) even when the polishing time is long, and the cumulative deleted weight becomes 26 (mg) in 210 hours. In Examples 1 to 4, the polishing ability gradually decreases as the polishing time increases, and these differences tend to increase.

  Also in this test, the amount of abrasion of the grinding wheel 10 of Example 1 was remarkably small and remained at about 4 (μm) after 210 hours, whereas in Comparative Example 2, it was about 163 (μm) after 60 hours. Significant wear was observed. In Comparative Example 3, no wear was observed in 60 hours.

  In short, in the present embodiment, the abrasive grains used in the polishing grindstone 10 are made of α-type alumina manufactured from alcoholate using a sol-gel method, and therefore when polishing a single crystal sapphire substrate. Both high polishing efficiency and good surface roughness can be obtained.

  In addition, in this embodiment, fine abrasive grains having an average particle diameter of about 0.6 (μm) are used, so that a better surface roughness can be obtained.

  Further, in this embodiment, since the binder is an epoxy resin having a low elastic modulus, it is easily retracted from the surface to be polished when a pressing force is applied from the surface to be polished of single crystal sapphire. For this reason, it is suitably suppressed that the surface to be polished is scratched, and a higher quality surface to be polished can be obtained.

  In the above-described embodiment, polishing is performed using the polishing grindstone 10 to which the abrasive grains are fixed. Instead of this, in the conventional free abrasive processing, the first embodiment is performed instead of colloidal silica. It is of course possible to use α-type alumina abrasive grains produced by the sol-gel method as used in ˜3. Even if it does in this way, compared with the free abrasive grain processing using the conventional colloidal silica, a high grinding | polishing capability is obtained in sapphire grinding | polishing. That is, in FIG. 2, the present invention is also applied to the case where polishing is performed by supplying a slurry containing abrasive grains from the nozzle 26 using a pad instead of the polishing grindstone 10.

  By the way, the abrasive grains constituting the polishing grindstone 10 in the present embodiment are determined based on experiments described below.

  FIG. 5 shows the results of performing the same free abrasive machining with these abrasive grains in order to evaluate the polishing efficiency of various abrasive grains including silica-based abrasive grains used in conventional free abrasive grain processing. It is shown. The evaluated abrasive grains were cerium oxide having an average particle size of about 0.8 (μm), synthetic mica having an average particle size of about 2.0 (μm), silica having an average particle size of about 1.0 (μm), and an average particle size of 0.6 ( μm) alumina (for example, WA # 10000), aluminum hydroxide having an average particle size of about 2.1 (μm), calcium fluoride having an average particle size of about 1.5 (μm), and conventionally used colloidal silica (For example, 2.5-fold diluted slurry of Compol EX-3). Of these, synthetic mica has recently been attracting attention in academic societies, and silica has the highest grinding ability in the past literature.

  The workpiece and the test device (lapping machine) are the same as those described above, and a φ300 (mm) pad (IC1000) is attached to the rotating shaft in place of the polishing grindstone 10, and 3 (vol%) in tap water. ) Was added onto the pad at a flow rate of 10 (ml / min). The rotation speed and other conditions are the same as in the evaluation described above.

  FIG. 5 shows the result of measuring the cumulative deleted weight after 30 minutes and after 60 minutes in such an evaluation test. As is apparent from the figure, only alumina showed an advantage over the conventional colloidal silica, and the cumulative deleted weight was about 2.3 times. Note that cerium oxide is not shown in the figure because it could not be polished at all.

  FIG. 6 shows the result of evaluating the various abrasive grains of a plurality of manufacturers under the same test conditions as described above in response to the result of FIG. Table 1 below shows the type and average particle size of each abrasive grain. The alphabetic characters in the symbol column of Table 1 correspond to the symbols attached to the respective data in FIG. In Table 1, when the crystal system is hexagonal, α-type, hexagonal + tetragonal and tetragonal are γ-type, monoclinic + orthorhombic are δ-type, monoclinic + The hexagonal crystal is called the θ type. As shown in FIG. 6, alumina abrasive grains vary greatly depending on the type, but most alumina abrasive grains have higher polishing ability than colloidal silica conventionally used.

[Table 1]
Symbol Type Average particle size Specific surface area Crystal system
Company A a WA # 10000 0.7 (μm) 21.6 (m ² / g) Hexagonal crystal
Company B b Alkoxide fine grain 0.3 82.8 Hexagonal crystal + tetragonal crystal c Alkoxide medium grain 0.4 24.3 Hexagonal crystal
d Alkoxide Coarse Grain 0.6 5.9 Hexagonal Crystal
Company C e Spherical alumina 0.7 5.8 Monoclinic + orthorhombic f Alkoxide fine 0.3 0.3 Hexagonal g Alkoxide coarse 0.6 0.6 4.8 Hexagonal fine alkoxide 0.1 or less 73.7 Monoclinic + hexagonal D Company i Alkoxide ultrafine 0.1 or less 134.9 Tetragonal j Fine powder in alkoxide 0.2 12.3 Hexagonal k Easy-sintering fine grains 0.4 4.9 Hexagonal l Easy-sintering coarse grains 0.8 2.5 Hexagonal crystals
m Buyer method 0.4 7.4 Hexagonal crystal

  Among the above abrasive grains, the three types (b to d) of Company B are all manufactured from alkoxides, but alumina b is not pregelatinized, and alumina c and d have different particle sizes. Therefore, it is estimated that the degree of firing is different.

  Alumina e does not use alkoxide as a starting material and is not α-ized.

  In addition, 4 types of f to i out of 8 types of D company are manufactured from alkoxide, and alumina h and i are not α-ized, and alumina f and g have different particle sizes from each other. These are estimated to have different degrees of firing. Alumina j is produced from an alkoxide in the same manner as alumina f and g, but is a fine powder obtained by cutting coarse particles to sharpen the particle size distribution. Alumina k, l is manufactured from alkoxide, but its shape is almost spherical due to the difference in the process. Alumina m is general alumina produced by the Bayer method.

  In the above evaluation, γ-type alumina i and δ-type alumina e have lower polishing ability than colloidal silica. Although it has higher polishing ability than colloidal silica, θ-type alumina h, γ-type alumina b, α-type alumina f, and alumina a (WA # 10000) are other α-types. Compared to the low characteristics.

  FIG. 7 shows the results of the free abrasive machining test using 11 types of abrasive grains excluding alumina i and e, which have a remarkably low polishing ability (that is, lower than the colloidal silica indicated by the broken line in the figure). The correlation between the surface roughness of the workpiece is shown on the horizontal axis, and the polishing removal weight after 60 minutes is shown on the vertical axis. As is clear from FIG. 7, the correlation between the surface roughness and the polishing removal weight is not so strong, and it tends to be an inverse correlation. The general correlation tendency between the surface roughness and the polishing removal weight in the case of grinding by mechanical action shows a positive correlation tendency as shown by the arrow extending toward the upper right. It is estimated that it has an influence on the ability (polishing efficiency).

  Further, in FIG. 7, “◯” distinguishes abrasive grains in which machining flaws have occurred on the workpiece surface, and “●” distinguishes abrasive grains in which no machining flaws have occurred. Moreover, since it is preferable that the abrasive grains have good surface roughness and a large deleted weight, according to the evaluation result, four abrasive grains of alumina c, d, g, and k located at the upper left are particularly preferable. I understand.

  FIG. 8 shows the correlation between the specific surface area of the abrasive grains and the polishing removal weight. In this figure, white marks (◯ □ ◇ △) represent α-type alumina, and black marks (● ◆ ★) represent γ-type, δ-type, and θ-type alumina. The shape of each mark corresponds to the production method and type of alumina, and ○ and ● are D companies produced by the sol-gel method Alumina f to j, and □ are D products produced by the sol-gel method Easily sintered alumina k, l, ◇ and ◆ are B-alumina b to d manufactured by the sol-gel method, Δ is pulverized alumina manufactured by the Bayer method (WA and D-alumina m), and ★ is C Alumina e.

  From the relationship between the difference in the crystal system of alumina shown in FIG. 8 and the polishing removal weight, it is clear that α-type alumina tends to have a higher polishing ability than other crystal systems. In addition, the smaller specific surface area tends to have higher polishing ability.

  Moreover, when it sees in relation to a manufacturing method, what was manufactured by the sol-gel method among (alpha) type is concentrated on the upper left except D company alumina f, and it is clear that these grinding | polishing capabilities are the highest. . Such a result was obtained because the alumina produced by such a production method has a high surface activity as known from the fact that it has a high sinterability, so that the polishing efficiency is increased by the chemical polishing action. It is thought that this is because

  From the relationship between the deleted weight, the surface roughness, and the specific surface area (particle diameter) shown in FIGS. 7 and 8, α-type alumina, and the abrasive grains produced from the alkoxide by the sol-gel method are sapphire. It is clear that it is suitable for polishing.

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is a perspective view which shows the whole grinding wheel. It is a figure which shows the implementation state of the finish grinding | polishing of the single crystal sapphire using the grinding wheel of FIG. It is a figure which shows the test result of the grinding stone of FIG. 1 with a comparative example. It is a figure which shows the other test result of the grinding stone of FIG. It is a figure which shows the test result which compared the polishing efficiency of various abrasive grains. It is a figure which shows the test result which compared the polishing efficiency of various alumina abrasive grains. It is the figure showing the relationship between the surface roughness of a to-be-polished surface and polishing efficiency in the test result of FIG. It is the figure showing the relationship between the specific surface area of an abrasive grain and polishing efficiency in the test result of FIG.

Explanation of symbols

10: Grinding wheel for sapphire polishing

Claims (5)

A grindstone for polishing sapphire for polishing and polishing one surface of single crystal sapphire to a predetermined surface roughness with a polished surface in which abrasive grains are bonded with a predetermined binder,
A grindstone for polishing sapphire, characterized in that the abrasive grains are made of α-type alumina produced by using a sol-gel method with alcoholate as a starting material. The grindstone for sapphire polishing according to claim 1, wherein the abrasive grains have an average grain size of 5 (µm) or less. A sapphire polishing method for finishing and polishing one surface of single crystal sapphire to a predetermined surface roughness,
A sapphire polishing method characterized by polishing while supplying abrasive grains made of α-type alumina produced by using a sol-gel method using alcoholate as a starting material to the one surface. The sapphire polishing method according to claim 3, wherein the abrasive grains have an average particle diameter of 5 (μm) or less. 4. The sapphire polishing method according to claim 3, wherein a polishing grindstone in which the abrasive grains are bonded with a binder is used.

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