JP2009113194A - Grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel capable of increasing grinding speed, eliminating replacement of a grinding wheel during grinding, achieveing high quality of a surface after the completion of grinding, and simplifying a polishing process. <P>SOLUTION: The grinding wheel grinds a backside of a wafer 12 for electronic material to a target thickness, and includes a plurality of phases of annular grinding surfaces. A diamond abrasive grain is fixed in the each phase from an external phase to an internal phase with various bonding material, and glass series bonding material is used as the bonding material of the diamond abrasive grain at the outermost phase. Besides, resin series bonding material is used at the internal phases excepting the outermost phase. The diamond abrasive grains of which diameters shown in the standard chart are identical are used, thus obtaining optimum characteristics for grinding the backside of the wafer 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grinding wheel used for grinding a back surface of a semiconductor integrated circuit or the like.

With the miniaturization of electronic devices, the mounting space for semiconductor integrated circuits is becoming increasingly smaller. Therefore, it is necessary to finish the thickness of the semiconductor integrated circuit thinner than before. However, reducing the thickness of the wafer tends to cause damage in the circuit manufacturing process, resulting in a decrease in yield. Therefore, after forming an integrated circuit on a wafer having a certain thickness, the back surface of the circuit is ground to a thickness of 100 μm or less (see Patent Document 1).
JP 2007-221054 A

When grinding the back surface of the wafer to the target thickness, if the entire grinding process is ground with a fine grinding stone for finish grinding, the grinding time becomes long. Therefore, a method is employed in which a rough grinding wheel that is several times rougher than the grinding wheel for finish grinding is used in the previous process, and a fine grinding wheel for fine grinding is used in the finishing process. However, since the grindstone is exchanged during the process, there is a problem that the exchange time affects the cost. In addition, there is a problem that it takes an unexpectedly long time to finish the roughly ground portion. Furthermore, there is a problem that it is not easy to grind the back surface of the wafer flatly at high speed operation.
In order to solve the above problems, an object of the present invention is to provide the following grinding wheel.

The following configurations are means for solving the above-described problems.
<Configuration 1>
An apparatus for grinding the back surface of a wafer for electronic materials to a desired thickness, comprising an annular grinding surface of a plurality of phases on one surface of the disk, and an acoustic impedance of 2 minutes with respect to the disk on a part of the disk. A grinding wheel characterized in that a vibration absorbing material of 1 or less is attached in an axially symmetric or uniform manner when viewed in the circumferential direction.

  The back surface of the wafer for electronic material can be stably ground by the annular grinding surface in which the diamond abrasive grains are fixed with different binders. The vibration absorbing material can suppress the unauthorized vibration of the disk. Thereby, it can planarize with high precision, without damaging the back surface of the wafer for electronic materials. If the vibration-absorbing material is axisymmetrically or uniformly attached, the center of gravity of the disk can be accurately concentrated on the shaft portion to prevent shaft shake.

<Configuration 2>
The grinding wheel according to Configuration 1, wherein the vibration absorbing material is made of a binder that fixes the diamond abrasive grains to the disk in any one of the plurality of phases.

  Since the binder for fixing the diamond abrasive grains to the disk also serves as a vibration absorbing material, the structure of the grinding wheel can be simplified. Moreover, the abnormal vibration of the diamond abrasive grains can be directly suppressed.

<Configuration 3>
In the grinding wheel according to Configuration 1 or 2, each phase from the outer phase to the inner phase has a diamond abrasive grain fixed by a different binding material, and the outermost phase diamond abrasive grain is bonded. A grinding wheel characterized by using a glass-based binder as an agent.

  When a glass-based binder is used, clogging is reduced and grinding can be started efficiently at high speed. The other phase uses another binder to stabilize the polishing performance. When diamond abrasive grains are fixed with different binders, the vibration absorption effect is high.

<Configuration 4>
In the grinding wheel according to Configuration 1 or 2, each phase from the outer phase to the inner phase has a diamond abrasive grain fixed by a different binding material, and the outermost phase diamond abrasive grain is bonded. A grinding wheel characterized by using an intermetallic compound binder as an agent.

  Like glass-based binders, it is less clogged and has good heat dissipation, making it suitable for high-speed grinding at the start of grinding.

<Configuration 5>
The grinding wheel according to Configuration 1 or 2, wherein the grinding wheel has a structure of two phases or three phases or more, and a resin binder is used for an inner phase other than the outermost phase.

  When an elastic resin-based binder is used for the inner phase, a stable finish is obtained.

<Configuration 6>
6. The grinding wheel according to any one of configurations 1 to 5, wherein diamond grains having the same grain size on the standard display are used for all phases.

  Even if diamond grains with the same grain size on the standard label are used for all phases, the binder of the outer phase and the inner phase is different, so the characteristics of the binder are utilized, and the good depending on the role of the outer phase and the inner phase Can bring out the best grinding performance.

<Configuration 7>
The grinding wheel according to any one of Structures 1 to 5, wherein a diamond abrasive grain having a small particle size on the standard display is used for the outer phase, and a diamond abrasive grain having a large particle size on the standard display is used for the inner phase. A grinding wheel characterized by that.

  Diamond abrasive grains having a small grain size on the standard display were used as the outermost phase that first contacted the back surface of the wafer to prevent chipping of the wafer edge. In addition, diamond abrasive grains having a smaller particle diameter are arranged on the outer phase side because vibrations generated during grinding are smaller.

<Configuration 8>
The grinding wheel according to configuration 7, wherein the abrasive grain has a structure of three or more phases, diamond abrasive grains having a small grain size on the standard display are used for the outermost phase, and diamonds having a large grain size on the standard designation are used for the next inner phase. A grinding wheel characterized by using abrasive grains and using diamond grains with small particle sizes on the standard display in order toward the inner phase.

  In the portion other than the outermost phase, diamond abrasive grains having a large grain size on the standard display are arranged on the outer phase side, so that the back surface of the wafer can be ground sufficiently quickly. Further, since diamond abrasive grains having a small particle size on the standard phase are arranged on the inner phase side, the surface roughness at the finish can be sufficiently reduced by grinding with the inner phase immediately after grinding with the outer phase.

<Configuration 9>
The grinding wheel according to any one of Structures 1 to 5, wherein a diamond abrasive grain having a small particle size on the standard display is used for the outermost phase, and the other is such that the particle size on the standard display is larger and the blocky as the outer phase. A grinding wheel with fixed diamond abrasive grains and fixed diamond abrasive grains that are smaller and sharper on the standard display as the inner phase.

  The blocky diamond abrasive grains are arranged on the outer phase side because they generate less vibration during grinding. Similar to configuration 1, blocky diamond abrasive grains have lower edge sharpness than sharp diamond abrasive grains, but have high mechanical strength and are suitable for roughing. A silicon wafer can be quickly ground to the desired thickness with blocky diamond abrasive grains, and the finished surface roughness can be reduced with sharp diamond abrasive grains on the inner periphery.

<Configuration 10>
10. The grinding wheel according to any one of Items 1 to 9, wherein a gap generated between phases of a plurality of annular grinding surfaces is selected to be 1 mm or less.

  Each phase of the multiple-phase annular grinding surface is preferably in close contact to maintain strength. However, when providing a gap for the purpose of drainage or clogging, the width is preferably 1 mm or less.

<Configuration 11>
The grinding wheel according to any one of configurations 1 to 5, wherein a portion constituting the annular grinding surface of any phase is divided into a plurality of regions in the circumferential direction of the ring, A grinding wheel characterized in that diamond abrasive grains are fixed by different binders, and any one of the fixing materials is a vibration absorbing material.

  If divided into a plurality of regions in the circumferential direction of the ring and diamond abrasive grains are fixed with different binders in each divided region, the acoustic impedance is different between adjacent divided regions, so that the vibration is damped. . In addition, the vibration absorbing effect was enhanced by mixing the fixing material that is a vibration absorbing material.

<Configuration 12>
The grinding wheel according to Configuration 1, wherein all the divided regions are arranged on the axis of the rotation axis of the disk.

  The shape and material of the divided areas are all evenly arranged so that the center of gravity of the disk is concentrated on the rotation axis, eliminating shaft shake.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

FIG. 1 is a perspective view showing a grinding wheel of Example 1. FIG.
The silicon wafer 12 on which the electronic circuit pattern is formed is supported by a suction chuck 11 (not shown) and rotates in the arrow A direction. The back surface of the electronic material wafer 12 is ground to a target thickness using a grinding wheel 10. The grinding wheel 10 is supported and fixed to the disk 14 and rotates in the direction of arrow b.

FIG. 2 is a longitudinal sectional view of the grinding wheel 10 and a partially enlarged view thereof.
The grinding wheel 10 includes a plurality of annular grinding surfaces 20 on one surface of a disk 14. In this example, the outer phase 16 and the inner phase 18 have a two-layer structure. Each phase is obtained by fixing diamond abrasive grains with a binder. As shown in FIG. 2, the grinding wheel 10 is formed by fixing a number of blocks having a length and height of several centimeters and a thickness of about 5 millimeters in an annular groove of the disk 14 with an adhesive or the like. is there. With the grinding wheel 10 having a diameter of about 20 cm, the back surface of a wafer having a diameter of about 250 to 300 mm can be ground.

FIG. 3 is a partial sectional view of the grindstone.
As the binder 24 for solidifying the diamond abrasive grains 22 into a grindstone, a metal-based binder, a resin-based binder, and a glass-based binder are known. A grindstone using a metal-based binder is characterized by excellent durability because it is elastic and sticky. The Young's modulus can be selected in the range of 10,000 to 100,000. On the other hand, a grindstone using a glass-based binder is hard and brittle, and is very worn, but has a feature that it is difficult to clog. Young's modulus can be selected in the range of 10,000 to 30,000. In addition, a grindstone using a resin-based binder has a characteristic that it is soft, has a good cushion, and is suitable for fixing diamond grains having a small particle diameter. Young's modulus can be selected in the range of 3,000 to 15,000.

  The grindstone of the present invention has an annular grinding surface of a plurality of phases, and makes the binder of each phase from the outer phase to the inner phase have different properties to bring out the desired grinding performance. Furthermore, by combining with the grain size of the diamond abrasive grains, it is possible to obtain a grinding performance more suitable for efficiently grinding the back surface of the wafer for electronic material.

  First, in Example 1, a two-phase structure or a three-phase structure or more is used, a glass-based binder is used as a binder for the outermost diamond abrasive grains, and a resin-based one is used for the other internal phases. To do. When a glass-based binder is used, clogging is reduced and grinding can be started efficiently at high speed. On the other hand, when an elastic resin-based binder such as a phenol resin or a thermosetting resin is used for the inner phase, a stable finish is obtained. The same effect can be obtained even when a relatively hard and brittle intermetallic binder is used in the outer phase. In addition, since intermetallic compound binders have good heat dissipation, they are suitable for high speed grinding.

  Further, when a glass-based binder or a hard and brittle intermetallic compound-based binder is used, the grinding surface of the grindstone is sequentially broken while grinding and new surfaces appear one after another. That is, the grinding performance does not deteriorate for a long time from the start of grinding. Therefore, the dressing process for adjusting the grinding surface of the grindstone before the start of grinding becomes unnecessary. In addition, for example, if diamond grains with a relatively small particle size of JIS standard indication # 600 to # 1000 are used for all phases, new surfaces appear one after another in the outer phase, so many diamond abrasive grains are effective. This contributes to grinding and maintains a high grinding speed. On the other hand, in the inner phase, there is an effect that diamond abrasive grains having a relatively small particle diameter act appropriately and can be ground to an optimum surface roughness. According to experiments, when compared to a grindstone using the same diamond abrasive grains for all phases and using a resin-based binder, the time during which equivalent grinding performance can be maintained increased by 15 to 20%.

  In this embodiment, the grain sizes of the outer and inner phase diamond abrasive grains are selected. Note that diamond abrasive grains are usually commercially available with a mixture of abrasive grains having a grain size of # 200 to # 400, even if the standard designation of grain size is # 325, for example. The range of variation is relatively large. However, at least, the larger the grain size on the standard display, the larger the number of diamond abrasive grains with larger grain size. Therefore, the grinding surface roughness is increased. The following will be described using this standard display.

  First, the diamond abrasive grains constituting the outermost phase 16 have a smaller grain size on the standard display than the diamond abrasive grains constituting the inner phase 18. For example, the outermost phase is made of diamond abrasive grains of standard designation # 1000 to # 2000, which are hardened with a glass-based binder. Further, the inner phase is made of diamond abrasive grains whose standard indication is about # 325 to # 600 and hardened with a resinous binder. When grinding of the back surface of the electronic material wafer is started, the outer phase grindstone first collides with the edge of the back surface of the wafer. At this time, if grinding is started all at once with diamond grains having a large particle size, there is a possibility that minute chips may be formed on the edge of the back surface of the wafer. Therefore, the diamond grains of the outer phase grindstone were made small. It is desirable that there are no missing edges, and this configuration contributes to a lower probability of occurrence.

  In addition, the grinding wheel is made into a three-phase structure, and diamond abrasive grains having a small particle size are used for the outer phase that first collides with the edge of the back surface of the wafer to satisfy the above-mentioned requirements. It is more preferable that the search speed is increased by using, and the innermost phase is finished using diamond grains having a small particle diameter. For example, compared to the one using diamond grains with a large particle size for the outermost phase, the one using diamond grains with a small particle size for the outermost phase has a grinding torque of about 30% lower and smooth grinding is possible. It was. Furthermore, a diamond grain having a small particle size was used for the outermost phase, a diamond particle having a large particle size was used for the inner phase, and a diamond particle having a small particle size was used for the inner phase. In comparison with the case where diamond abrasive grains having a large particle diameter were used for the outermost phase, the grinding torque was reduced by about 50%. The smaller the grinding torque, the smoother and flatter the grinding.

  In the above example, grindstones made of diamond abrasive grains having different grain size specifications are arranged in the outer phase and the inner phase. In this example, like the example 2, the outermost phase has a grain size smaller on the standard display than the diamond abrasive grains arranged on the inner phase side. At the same time, the other phases fix diamond abrasive grains having a larger grain size on the standard display as the outer phase and a diamond grain having a smaller grain size on the standard display as the inner phase. In general, commercially available blocky diamond abrasive grains have lower edge sharpness than sharp diamond abrasive grains, but have high mechanical strength and are suitable for roughing. Sharp diamond abrasive is suitable for finishing with fine surface roughness.

  Therefore, by arranging the blocky diamond abrasive grains and the sharp diamond abrasive grains in the outer phase and the inner phase, it is possible to realize a long-life grinding wheel that is more stable than that of the first embodiment. Of course, it is possible to search at high speed and to grind with good finish.

FIG. 4 is an explanatory view showing the grinding effect of the grindstone.
The vertical axis (Y) of the graph in the figure indicates the surface roughness of the wafer back surface. The horizontal axis (X) is a position on a straight line across the wafer back surface. The greater the vertical deflection, the more uneven the surface after grinding. The left end of the graph is the edge of the wafer. (A) of the figure uses # 1000 diamond abrasive grains for the outer phase and the inner phase. The outer phase is obtained by hardening the diamond abrasive grains with a glass-based binder, and the inner phase is hardened with a resin-based binder. The roughness of the finished surface sufficiently satisfies the requirements. When diamond abrasive grains of # 2000 are used, the finish is close to (b) in the figure.

  On the other hand, (b) in the figure uses # 2000 diamond abrasive grains as the outermost phase, hardened with an intermetallic binder, and # 600 blocky diamond abrasive grains with a glass binder. The state of the finished ground surface with a three-phase structure grindstone in which # 1000 sharp diamond abrasive grains are solidified with a resin binder and used in the third phase is shown. The roughness of the finished surface sufficiently satisfies the requirements. Moreover, although the search speed was improved, no missing edge was detected. (C) of the figure shows the state of the finished ground surface with a grindstone having a structure in which only # 600 diamond abrasive grains are used and hardened with a resin-based binder. Not only is the surface roughness not achieved, but clogging occurs and performance is degraded. Each shows a state after a 6-inch silicon wafer is fixed on a table that rotates 200 times per minute, a grindstone is applied to the back surface and driven at 3000 revolutions per minute, and is ground by about 100 μm.

FIG. 5 is an explanatory diagram comparing the durability of the grindstone.
The vertical axis of the graph in the figure represents the rotational torque of the motor that rotationally drives the grindstone. The horizontal axis indicates the accumulated grinding time. In each case, a 6-inch silicon wafer was fixed on a table rotating at 200 rpm, and a grinding stone was applied to the back surface of the 6-inch silicon wafer and driven at 3000 rpm, and the process of grinding about 100 μm per sheet was repeated. When the grinding function is reduced due to clogging or the like, the load on the motor increases and the rotational torque increases. It can be said that the smaller the fluctuation of the rotational torque for a long time, the better the grindstone.

  A in the figure is for the grindstone used in FIG. 4A, B in the figure is for the grindstone used in FIG. 4B, and C in the figure is for the grindstone used in FIG. 4B. Indicates. When diamond abrasive grains fixed with a glass-based binder or an intermetallic compound-based binder are arranged in the outermost phase or the outer phase as in the examples of A and B, clogging is less and the life is relatively long. I understand that. On the other hand, when all diamond abrasive grains are fixed with a resin-based binder as in the case of C, clogging occurs, the rotational torque gradually increases, and the grinding ability decreases in a short time.

  It was also found that a two-phase structure and a three-phase structure can be obtained that are sufficiently durable when a binder is used in the same manner as in the above examples. In addition to this, even if the grinding wheel is ground for the same time, the surface roughness at the end of the grinding process is sufficiently small compared to the conventional grinding wheel, so that the subsequent polishing process of the substrate surface can be shortened. There is an effect. In addition, the finished surface can be of high quality. In addition to the applications of the examples, the above-described grindstone can be effectively used for, for example, the back grinding of compound semiconductors and the grinding of SiC, ferrite, and sapphire materials.

FIG. 6 is an explanatory diagram of acoustic characteristics of the vibration absorbing material.
In the operation of grinding the back surface of the electronic material wafer to a target thickness, the disk 14 shown in FIG. 1 is rotated at a high speed. At this time, unexpected improper vibration is generated in each part of the disk 14, and the contact pressure of the grinding surface 20 (FIG. 2) against the back surface of the electronic material wafer is changed. According to experiments, this adversely affects the flatness of the back surface of the electronic material wafer after grinding.

  Therefore, a vibration absorbing material is used to suppress the vibration of the disk 14. When considering the processing speed, the object to be polished, etc., vibration absorption design may be performed by paying attention to the acoustic impedance of the structure. As shown in FIG. 6, the metal that is the material of the disk 14 has an acoustic impedance of 40,000,000 Ns (Newton · second) per cubic meter. On the other hand, vitrify bond that can be used as a fixing material for diamond abrasive grains is a vitreous binder, and has an acoustic impedance that is less than half that of metal. In addition, the resin-based binder has an acoustic impedance of 1/10 or less of that of metal.

  If two or more kinds of materials having a difference in acoustic impedance are brought into contact with each other, various improper vibrations of each part of the disk 14 can be absorbed by these interfaces. For example, when vitrify bond is used as a binder for fixing diamond abrasive grains to the outermost phase of the disk, vibration can be absorbed and the contact with the back surface of the electronic material wafer can be softened. For example, if the outer phase is vitrified bond, the intermediate phase is an intermetallic compound, and the inner phase is a resin-based binder, each phase from the outer phase to the inner phase fixes the diamond abrasive grains with different binders. The vibration absorption effect is enhanced by the difference in acoustic impedance. Actually, the effect of the vibration absorbing material greatly contributes to the grinding effect described in FIG. Note that the problem with acoustic vibration here is that the frequency ranges from several tens of hertz to several thousand hertz. In some cases, the entire disk vibrates, a part of the disk vibrates, or each part integrated with the disk vibrates.

FIG. 7 is a longitudinal sectional view of the grinding wheel of the fifth embodiment. FIG. 8 is a front view of the grinding wheel of the fifth embodiment.
As shown in FIGS. 7 and 8, in this embodiment, the vibration absorbing material 26 is attached to a part of the disk 14. In this example, four block resin materials are bonded and fixed in the circumferential direction of the disk 14. The vibration-absorbing material 26 is preferably attached in an axially symmetric or uniform manner when viewed in the circumferential direction. As a result, the center of gravity of the disk 14 can be accurately concentrated on the shaft portion, and shaft shake can be prevented. This measure is suitable when the diamond abrasive binder alone is insufficient. From this, the Examples 1 to 4 described above also have an effect that the structure of the grinding wheel can be simplified because the binder for fixing the diamond abrasive grains also serves as a vibration absorbing material.

  Further, when a vibration absorbing material is used as a binder for fixing diamond abrasive grains, vibration generated by friction between the back surface of the wafer for electronic materials and the diamond abrasive grains can be directly absorbed. That is, vibration absorption is not simply due to physical properties such as the Young's modulus of the binder alone, but due to the difference in acoustic impedance between the diamond abrasive grains, the binder and the disk, the acoustic vibration is attenuated at these interfaces. The part that occurs is large. Further, the outer peripheral portion of the disk has a relatively high rotational speed, and abnormal vibration is likely to occur. Therefore, if a vibration absorbing material is used for the binder that fixes the diamond abrasive grains of the (outer phase) on the outer peripheral portion, it can be said that the effect of flattening the back surface of the electronic material wafer is remarkable. Further, as shown in FIG. 2, since the outer phase 16 and the inner phase 18 are overlapped, it can be said that the vibration absorption effect is higher when the acoustic impedances of the two are different. The vibration absorption effect is higher as the difference in acoustic impedance is larger, and it can be said that a resin-based binder having an acoustic impedance of 1/10 or less of metal is more effective.

FIG. 9 is a front view of the grinding wheel of the sixth embodiment.
In the illustrated grinding wheel, the portion constituting the annular grinding surface is divided into six regions in the circumferential direction of the ring. For example, in the divided regions constituting the annular grinding surface 20a, diamond abrasive grains are fixed with vitrify bonds. Moreover, the diamond abrasive grain was fixed with the thermosetting resin in the division | segmentation area | region which comprises the cyclic | annular grinding surface 20b. Two kinds of binders are used at three locations alternately in the circumferential direction. Here, a resin-based binder exhibits a particularly high vibration damping effect. If the acoustic impedance is different between adjacent divided regions, the acoustic vibration propagation in the circumferential direction is hindered, and the vibration preventing effect is enhanced. In this way, even when the divided regions using the vibration absorbing material are mixed in the binding material, it is preferable that the shapes and materials of the divided regions are all equally arranged as viewed from the axis of the disk. That is, as in the embodiment of FIG. 9, all the divided areas are arranged on the axis object with respect to the rotation axis of the disk. As a result, the center of gravity of the disk can be concentrated on the rotation axis, and the shaft shake can be eliminated.

1 is a perspective view showing a grinding wheel of Example 1. FIG. It is the longitudinal cross-sectional view of the grinding wheel, and its partial enlarged view. It is a fragmentary sectional view of a grindstone. It is explanatory drawing which shows the grinding effect of a grindstone. It is explanatory drawing which compared the durability of the grindstone. It is an acoustic characteristic explanatory view of a vibration absorption material. It is a longitudinal cross-sectional view of the grinding wheel of Example 5. 6 is a front view of a grinding wheel of Example 5. FIG. It is a front view of the grinding wheel of Example 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Grinding wheel 12 Wafer 14 Disc 16 Outer phase 18 Inner phase 20 Grinding surface 22 Diamond abrasive grain 24 Binder 26 Vibration absorbing material

Claims (12)

For grinding the back surface of the wafer for electronic materials to a desired thickness,
It has a multi-phase annular grinding surface on one surface of the disk,
A grinding wheel characterized in that a vibration absorbing material having an acoustic impedance of ½ or less with respect to the disk is attached to a part of the disk in an axially symmetric or uniform manner as viewed in the circumferential direction. In the grinding wheel according to claim 1,
The vibration-absorbing material is made of a binder that fixes the diamond abrasive grains to the disk in any one of the plurality of phases. In the grinding wheel according to claim 1 or 2,
Each phase from the outer phase to the inner phase has a plurality of annular grinding surfaces, and diamond abrasive grains are fixed with different binders, and a glass-based binder is used as a binder for the outermost diamond grains. A grinding wheel characterized by that. In the grinding wheel according to claim 1 or 2,
Each phase from the outer phase to the inner phase has a plurality of annular grinding surfaces, and the diamond abrasive grains are fixed with different binders, and an intermetallic compound binder is used as a binder for the outermost diamond abrasive grains. A grinding wheel that is used. The grinding wheel according to claim 1 or 2,
A grinding wheel characterized by having a structure of two phases or three phases or more, and using a resin-based binder for an inner phase other than the outermost phase. A grinding wheel according to any one of claims 1 to 5,
A grinding wheel characterized in that diamond grains having the same grain size on the standard label are used for all phases. A grinding wheel according to any one of claims 1 to 5,
A grinding wheel characterized in that diamond grains having a small particle size on the standard display are used for the outer phase, and diamond grains having a large particle size on the standard display are used for the inner phase. The grinding wheel according to claim 7,
A structure with three or more phases, diamond abrasive grains with a small particle size on the standard display are used for the outermost phase, and diamond abrasive grains with a large particle size on the standard display are used for the next inner phase, toward the inner phase. A grinding wheel characterized in that diamond abrasive grains having smaller particle sizes on the standard display are used. A grinding wheel according to any one of claims 1 to 5,
For the outermost phase, diamond grains with a smaller particle size on the standard display are used. For the other phases, a diamond particle with a larger particle size on the standard display as the outer phase is fixed, and for the inner phase, the grain size on the standard display is fixed. A grinding wheel with small and sharp diamond grains fixed. In the grinding wheel according to claim 1 to 9,
A grinding wheel characterized in that a gap generated between phases of a plurality of annular grinding surfaces is selected to be 1 mm or less. A grinding wheel according to any one of claims 1 to 5,
The portion constituting the annular grinding surface of any phase is divided into a plurality of regions in the circumferential direction of the ring, and in each divided region, the diamond abrasive grains are fixed by different binders, and any one of the fixings A grinding wheel characterized in that the material is a vibration absorbing material. The grinding wheel according to claim 1,
The grinding wheel according to claim 1, wherein all of the divided regions are arranged on an axis with respect to a rotation axis of the disk.

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