JP2005153106A - Polishing tool, polishing tool manufacturing method, polishing method, and polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems of a polishing tool, including increased machining resistance, abrasive slipout, and clogging with chips, occurring in polishing a component part such as a silicon wafer. <P>SOLUTION: The polishing tool has a base material, and a polishing layer fixed to the base material by means of a binder and having abrasive grains and magnetic grains, or abrasive grains formed of a magnetic material. Then a magnetic field is applied to the polishing tool from outside to oscillate the polishing layer in a direction perpendicular to a surface to be machined. Thus a time period for which the abrasive grains make contact with the surface to be machined is shortened, and therefore incision in the surface to be machined by the abrasive grains can be made fine, leading to reduction in damage on the surface to be machined. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing tool, a polishing tool manufacturing method, a polishing method, and a polishing apparatus in polishing processing.

  Fixed abrasive processing that can provide excellent finished surface roughness equivalent to polishing finish using loose abrasive for final finishing of parts made of various hard and brittle materials and metal materials such as silicon wafer and glass disk Tools are actively being developed in various directions. In order to obtain a good surface roughness in abrasive processing, it is usually advantageous to use fine abrasive grains, and the same applies to fixed abrasive processing tools. However, in order to obtain an excellent processed surface such as a mirror surface, when using abrasive grains having a particle size of several μm or less in a fixed abrasive processing tool, contact between the abrasive binder and the workpiece is likely to occur during processing. A sharp increase in processing resistance, dropping of abrasive grains, and the like occur, and in the worst case, the processing becomes impossible. Further, clogging due to chips or the like not only lowers the processing efficiency but also causes a problem that scratches and scratches are again given to the mirror surface obtained.

  As a solution to these problems, there is a fixed abrasive machining tool that uses finely divided abrasive grains and uses agglomerated powder as abrasive grains. Patent Document 1, Patent Document 2 and the like describe agglomerated abrasive grains. An invention relating to a polishing tool fixed on a base material with a binder resin has been made. In these fixed abrasive processing tools, excellent surface roughness is obtained by the action of fine abrasive grains, and at the same time, achievement of high processing efficiency is realized by the aggregated abrasive grains. Further, in Patent Document 3, attention is paid to the bonding state of fine primary particles, and abrasive wear can be gradually progressed in abrasive grains produced by the disclosed invention, and chips are also worn away by abrasive grains. At the same time, they are discharged and can avoid clogging, while at the same time trying to achieve high machining surface quality with high machining efficiency.

  FIG. 5 is an enlarged cross-sectional view of a polishing tool manufactured by the manufacturing methods disclosed in Patent Document 1, Patent Document 2 and Patent Document 3, and this polishing tool is made of abrasive grains 2 by a binder 11 on a substrate 12. The abrasive grains 2 are securely fixed on the base material 12 and the protruding amount from the binder 11 is guaranteed. Further, the binder portion around the abrasive grains serves as an accumulation place for the discharged chips 21 and the worn abrasive grains 2. However, in the above invention, abrasive grains having a large particle size are used, and as the processing proceeds, the abrasive grains are flattened and worn, and chips are discharged simultaneously with the abrasive wear. However, this does not always work smoothly, and is still insufficient for complete suppression of scratches. Specifically, there are a large number of working abrasive grains that come into contact with the work surface of the workpiece. Among them, even one abrasive grain has too much internal fine particle bonding (the abrasive grains are There are cases where scratches easily occur (too hard). In particular, if the object to be processed has a large diameter, since many abrasive grains participate in the processing at the same time, this adverse effect may be more noticeable.

  In order to solve this problem, there is a conventional processing technique using minute vibration. Especially, grinding using ultrasonic waves has been actively studied. Examples include Patent Document 4 and Patent Document 5. In Patent Document 4, a laminated piezoelectric actuator is attached to a grindstone, and ultrasonic processing is used at the time of processing to promote the progress of the processing, and the invention aims at higher efficiency. However, with such a technique, the amplitude of the ultrasonic wave is large and effective in promoting the progress of processing, but before solving the problem of suppressing scratches, an excellent processing surface, usually called an optical mirror surface, is obtained. This is considered very difficult.

As a result of further diligent research on these problems, the present inventors introduced second particles made of magnetic particles in addition to abrasive grains into the polishing layer fixed on the base material with a binder, or The abrasive grains themselves are magnetic particles, and the external magnetic field is changed during processing, and the abrasive layer, or at least the abrasive grains, vibrate in the vertical direction with respect to the work surface of the workpiece, and contact between the abrasive grains and the work surface of the work By shortening the time, minimizing the incision on the workpiece surface by the abrasive grains and shortening the time, it avoids sudden stress concentration due to processing such as scratches due to variations in the grain size and hardness of the abrasive grains. It has been found that new processing damage due to can be suppressed, high processing efficiency is not sacrificed, and it is extremely effective to obtain high processing surface quality more reliably.
JP 2000-190228 A Japanese Patent Laid-Open No. 2000-237962 JP 2003-105324 A Japanese Patent Laid-Open No. 5-200659 Japanese Patent Laid-Open No. 9-207072

  An object of the present invention is to polish the grain size of abrasive grains existing in the polishing layer, the amount of protrusion of the abrasive grains, and the hardness of the processed surface of the workpiece by the polishing layer in which the abrasive grains are fixed on the base material with a binder. Suppression of scratches due to variations in thickness, etc., and focusing on the polishing characteristics of the polishing tool that guarantees high processing surface quality. The polishing layer, at least abrasive grains fixed to the polishing layer, is used as the processing surface. On the other hand, by making minute vibrations in the vertical direction, the contact time between the abrasive grains and the work surface of the workpiece is shortened, and the cutting of the abrasive grains into the workpiece surface is miniaturized, thereby reducing the grain size and hardness of the abrasive grains. Abrupt stress concentration due to variation can be avoided, new processing damage such as scratches due to processing can be suppressed, and high processing surface quality can be reliably obtained without sacrificing high processing efficiency, Cheap and easy to manufacture Kill polishing tool and processing apparatus using the same, it is to provide a machining method.

  In order to solve the above-described problems, the present invention provides a polishing layer that is fixed on a base material with a binder by sliding a polishing layer against a processed surface of a workpiece and polishing the polishing layer with respect to the processed surface. , And means for causing minute vibrations in a vertical direction.

  According to the present invention, the polishing layer includes second particles made of magnetic particles in addition to the abrasive grains. By changing the external magnetic field, the polishing layer is made minute in a direction perpendicular to the processed surface. It is characterized by causing vibration.

  According to the present invention, the polishing layer includes abrasive grains made of magnetic particles, and the external magnetic field is changed to cause the polishing layer to vibrate in a direction perpendicular to the processing surface. And

  According to the present invention, in the polishing layer of the polishing tool, the particle size of the second particles made of the magnetic particles is smaller than the particle size of the abrasive particles.

  According to the present invention, in the polishing layer of the polishing tool, the second particles made of magnetic particles are included in a binder that fixes the abrasive grains to the surface of the substrate, and the binder that fixes the abrasive grains to the surface of the substrate. The thickness of is smaller than the maximum diameter of the abrasive grains.

  In the polishing layer of the polishing tool, the content of the abrasive grains is 10% by volume or more and 90% by volume or less.

  In the present invention, a patterned ferromagnetic material having a large number of constant shapes is embedded under a polishing tool, and an electromagnet is disposed under the ferromagnetic material. Is generated by the electromagnet.

  The present invention is also characterized in that the ferromagnetic material buried under the polishing tool is soft magnetic and has a saturation magnetization of 0.8 Tesla or more.

  The present invention also includes a mixing step of mixing the second magnetic particles with the abrasive grains, a step of preparing a coating solution by adding a binder, and a magnetic field in a direction perpendicular to the surface of the substrate in advance. And the step of applying the coating solution onto the substrate in an environment where a magnetic field exists.

  Further, the present invention is a polishing apparatus using the polishing tool and the polishing method.

  According to the present invention, a polishing layer in which abrasive grains are fixed on a substrate with a binder is slid with a processing surface of a workpiece and the polishing layer is minute in a direction perpendicular to the processing surface during polishing processing. By using a means to vibrate, during polishing, the contact time between the abrasive grains and the work surface is shortened, and the cutting of the abrasive grains into the workpiece surface is miniaturized, resulting in variations in the grain size and hardness of the abrasive grains. Therefore, sudden stress concentration due to machining such as scratching can be avoided, new machining damage caused by machining can be suppressed, and high machining surface quality can be reliably obtained without sacrificing high machining efficiency.

  Further, according to the present invention, the polishing layer contains second particles made of magnetic particles in addition to the abrasive grains, or abrasive grains that are magnetic bodies, and the polishing layer is more reliably formed on the processed surface by changing the external magnetic field. On the other hand, minute vibrations can be caused in the vertical direction. For example, when an external magnetic field is turned on / off at a certain frequency during polishing, magnetic particles are attracted in the direction of the magnetic field when turned on, and when the magnetic field is turned off, the magnetic particles are released from attraction by the magnetic field, and the elasticity of the binder To return to the original position. Therefore, if this motion is repeated, the polishing layer or abrasive grains in the vertical direction of the machined surface are subjected to minute vibrations, the contact time between the abrasive grains and the workpiece machining surface is shortened, and the workpiece surface is cut by the abrasive grains. By miniaturizing, it is possible to avoid sudden stress concentration due to processing such as scratches due to variations in the grain size and hardness of the abrasive grains, and to suppress new processing damage due to processing.

  Further, according to the present invention, since the particle size of the second particles made of magnetic particles is smaller than the particle size of the abrasive particles, the magnetic particles can be more reliably contained in the binder of the polishing layer, It plays the role which raise | generates the vibration of a grinding | polishing layer or an abrasive grain at the time of a process, and can suppress the bad influence by this 2nd particle | grains being exposed to a processing surface.

  According to the present invention, the second particles made of magnetic particles are included in the binder that fixes the abrasive grains to the surface of the substrate, and the thickness of the binder that fixes the abrasive grains to the surface of the substrate is the maximum of the abrasive grains. By being smaller than the diameter, the state in which the abrasive grains protrude from the binder is maintained during polishing, and the workpiece can be finished with high efficiency and high accuracy more reliably and stably.

  Further, according to the present invention, when the abrasive content is 10% by volume or more and 90% by volume or less, it is possible to particularly effectively achieve a highly efficient and high-quality processed surface. If the addition rate of the composite particles is less than 10% by volume, the effect of the addition is not obtained. Can not.

  Further, according to the present invention, the second particle composed of the magnetic particles contained in the polishing layer or the magnetic material to the abrasive grains is controlled by controlling the change of the external magnetic field without requiring a large dedicated device. It can be vibrated at a certain frequency.

  Further, according to the present invention, the ferromagnetic material buried under the polishing tool is soft magnetic, and if the saturation magnetization is 0.8 Tesla or more, even if the magnetic field generated by the electromagnet is small, the ferromagnetic material Is more easily excited, a larger magnetic flux density can be obtained, and magnetic particles having a small particle diameter can be reliably adsorbed. Further, since the ferromagnetic material is soft magnetic, the residual magnetization is small and can be followed by a change in the external magnetic field, and the polishing layer or the abrasive grains can be vibrated minutely more reliably.

  According to the invention, according to the step of generating a magnetic field in a direction perpendicular to the surface of the substrate in advance and applying the coating liquid on the substrate in an environment where the magnetic field exists, the second step comprising the magnetic particles is performed. The particles can be distributed closer to the substrate. The effect of this is that, first, the magnetic particles are close to a ferromagnetic material embedded under the polishing tool, and thus are more easily attracted during processing and polishing. Furthermore, the magnetic particles can be more reliably retained inside the binder, and exposure to the processed surface during processing can be suppressed.

  Further, according to the present invention, no complicated equipment is required, and at the time of polishing, the polishing layer, at least the abrasive grains, can be vibrated minutely in the vertical direction with respect to the processing surface. By shortening the contact time with the machined surface and minimizing the incision on the workpiece surface by the abrasive grains, it avoids sudden stress concentration due to variations in the grain size and hardness of the abrasive grains. New processing damage can be suppressed, high processing efficiency can be reliably obtained without sacrificing high processing efficiency.

Hereinafter, the polishing tool according to the present invention will be described with reference to the drawings.
In the polishing tool of the present invention, as shown in FIG. 1, abrasive grains are fixed on one surface of a substrate 12 with a binder containing second particles made of a magnetic material.
When manufacturing the polishing tool, as shown in the plan view of the polishing tool applicator shown in FIG. 3, a coating solution containing second fine particles made of abrasive grains and magnetic material is applied on the base 12 in advance. To do. At this time, a magnetic field orthogonal to the plane of the substrate is applied. Therefore, the second fine particles made of the magnetic material are attracted to the vicinity of the base material due to the presence of the external magnetic field, and can be surely included in the binder, and the second fine particles are exposed to the processing surface. Therefore, the protruding amount of the abrasive grains can be reliably ensured.

  Further, in the polishing layer, the substantial thickness of the binder 11 for fixing the abrasive grains on the base material is smaller than the average grain diameter of the abrasive grains 2, so that the upper body in which the abrasive grains protrude from the binder during the polishing process. Maintaining and improving finishing accuracy. As the abrasive 2, although it depends on the object to be processed, it is generally a hard inorganic material, and a fine powder of primary particles having an average particle size of 5 μm or less aggregates to have an average particle size of about 10 to 300 μm. More preferably, those having a secondary particle size of about 40 to 100 μm in average particle size are suitable. Materials used for the normal abrasive grains 2 are silica, ceria, diamond, CBN (cubic boron nitride), alumina, silicon carbide, zirconium oxide, and the like. Aggregates can be produced by means such as a sol-gel method or a spray dryer (and generally used single particle abrasive grains that are not agglomerated are also possible).

  In addition, by making the particle diameter of the magnetic particles smaller than the particle diameter of the abrasive grains, the magnetic particles can be more reliably included in the binder of the polishing layer. Thereby, it plays the role which raise | generates the vibration of a grinding | polishing layer or an abrasive grain at the time of grinding | polishing, and can suppress the bad influence by a magnetic body particle being exposed to a processed surface.

  Moreover, a highly efficient and high quality processed surface can be obtained by making the content rate of an abrasive grain into 10 volume% or more and 90 volume% or less. When the addition rate of the abrasive grains is less than 10% by volume, the effect of the addition is not obtained. Can not.

  According to the polishing tool manufactured by the manufacturing method as described above, the abrasive grains 2 can be reliably fixed on the base material 12 and, at the same time, the second fine particles made of a magnetic substance are It is drawn close to the material and can be surely included in the binder, and the protruding amount of the abrasive grains can be reliably ensured without exposing the second fine particles to the processing surface. Therefore, by changing the external magnetic field during processing, the polishing layer or abrasive grains can be vibrated minutely in the direction perpendicular to the processing surface, reducing the contact time between the abrasive grains and the workpiece processing surface. By minimizing the incision on the workpiece surface by grains, sudden stress concentration due to scratching due to variations in grain size and hardness of abrasive grains can be avoided, and new machining damage due to machining can be suppressed. Therefore, it is possible to reliably obtain an excellent processed surface quality of nanometer order without sacrificing high processing efficiency.

The first embodiment of the present invention will be described below.
First, ultrafine ZrO ₂ powder (ultrafine particles) consisting of 50 to 60 nm is made muddy with water and sprayed with a spray dryer to have secondary particles (granules) having a desired size, for example, an average particle diameter of 60 μm. (In general, sizes from 1 μm to 300 μm are obtained. Add a classification process when the particle size distribution is not sharp).

The average particle diameter was measured by a dry method using a laser diffraction / scattering particle size distribution measuring apparatus LA-920 manufactured by Horiba. For the average particle size, the particle size at a frequency integration of 50% was used (usually also referred to as median diameter). However, the binding force between primary particles of a granule usually produced by a spray dryer may be too weak. Therefore, if necessary, ZrO ₂ granules were placed in an electric furnace and fired. Moreover, in order to shorten baking time or in order to raise hardness further, it may carry out in the pressurized state at the time of baking.

  Although primary particles grow by heat treatment, the primary particles grow not only by the mass transfer of the constituent substances, but also the bonding points between the particles become thicker due to the mass transfer of the constituent substances of the particles, and there are no discontinuities. It has a gentle curved surface and a so-called “neck” shape constricted in a one-leaf hyperboloid shape (a drum shape). Regarding the growth of primary particles and the formation of “neck” by mass transfer during the heat treatment, “2. Ceramic material technology collection” issued by the Industrial Technology Center Co., Ltd. (first edition issued on April 10, 1979) “2. 3 “Mass transfer mechanism and sintering model”. In this firing step, by controlling the heating temperature and holding time, a neck is formed at the bonding point between the primary particles, and a large number of the primary particles are partially formed and voids are formed therebetween. It formed into the granular porous body couple | bonded by.

Next, the ZrO ₂ abrasive grains were mixed with magnetic particles. Examples of the composition of the magnetic particles include FeO.Fe ₃ O ₄ , Fe ₂ O ₃ , Ni, and Co. A fine powder having an average particle size of 5 μm or less is desirable. Here, iron oxide (FeO.Fe ₃ O ₄ ) having an average particle diameter of 5 μm was used. Then, after adding a solvent to the liquid urethane resin and adjusting the solution viscosity to the mixture, as shown in FIG. 3, in a magnetic field perpendicular to the surface of the substrate (for example, PET having a thickness of about 75 μm). The coating liquid containing the abrasive grains and the second particles of FeO.Fe ₃ O ₄ was applied using a wire bar coater. Finally, the coated polishing tool was dried at about 60 ° C. for about 1 hour in a thermostatic bath (manufactured by Yamato Kagaku) to prepare a polishing tool.

  The polishing tool thus produced was attached to a surface plate in which the patterned ferromagnetic material shown in FIG. 2B was embedded. As the material of the surface plate, for example, a nonmagnetic material such as SUS304 or ceramics was used. As shown in FIG. 2A, the ferromagnetic material has a certain shape, for example, a circular shape, a rectangular shape, a line shape, or a ring shape (here, a circular shape will be described as an example). The circular ferromagnets are arranged in a lattice pattern or a staggered pattern at regular intervals.

  A directional silicon steel plate was used as the ferromagnetic material (saturation magnetization was 1.0 T). A magnetic field is periodically generated according to the frequency of the current by turning on / off the current flowing through the electromagnet under the surface plate in which the ferromagnetic material is embedded at a certain frequency. In addition, the magnitude of the magnetic field and the pattern of generation are controlled by the magnitude of the current that flows through the electromagnets during machining and whether the currents are flowed simultaneously to each electromagnet in a timely manner or selectively through each electromagnet. To do. Thereby, the vibration of the polishing layer or the abrasive grains is controlled.

  By selecting a soft magnetic material (high magnetic permeability and low coercive force) as the ferromagnetic material and using a material having a saturation magnetization of 0.8 Tesla or higher, the ferromagnetic material can be used even if the magnetic field generated by the electromagnet is small. By exciting more easily, a larger magnetic flux density can be obtained, and magnetic particles having a small particle diameter can be reliably adsorbed. Further, since the ferromagnetic material is soft magnetic, the residual magnetization is small and can be followed by a change in the external magnetic field, so that the polishing layer or the abrasive grains can be caused to vibrate more reliably.

  As shown in FIG. 1B, the presence of magnetic particles under each abrasive grain makes it possible to determine the abrasive grains a or the surrounding polishing layer into which a is incorporated when an external magnetic field is generated. When it is attracted to the board and then the magnetic field is turned off, it is returned to the original position again by the elasticity of the binder. By repeating this operation, the abrasive grains or the polishing layer can periodically cause minute vibrations.

  In addition, the amplitude can be controlled by replacing the size of the magnetic particles, the current of the electromagnet, and the ferromagnetic material with different saturation magnetization embedded in the surface plate. The amplitude that can be generated by this control was about 1 μm. A result of processing a BK7 optical glass disk of φ150 mm adjusted to a mirror surface having a surface roughness of about 30 nm Ry in 3 minutes with the processing apparatus shown in FIG. 4 (processing conditions: platen rotational speed 60 rpm, A mirror surface having a processing pressure of 30 kPa), processing marks (scratches, processing scratches, etc.) free and maintaining 30 nm Ry could be obtained (surface roughness was evaluated by Taylor Hopson's Form Talysurf S4C). Further, even when 10 glass disks were subsequently processed, no scratches were observed.

In the same manufacturing method as in Example 1, ZrO ₂ was used as abrasive grains and iron oxide FeO · Fe ₃ O ₄ was used as magnetic particles. The average particle size was 30 μm. No external magnetic field was applied during the production of the polishing tool. In this case, a gravure coater, a reverse roll coater, a knife coater, etc. can be used in addition to the wire bar coater. In the same manner as in Example 1, the polishing tool produced in this way was attached to a surface plate of a polishing apparatus (FIGS. 2 and 5), and a BK7 optical glass disk with a diameter of 150 nm adjusted to a mirror surface having a surface roughness of about 30 nm Ry was used. Results of processing in minutes (processing conditions: surface plate rotation 60 rpm, processing pressure 30 kPa), processing marks (scratches, processing scratches, etc.) free, and a mirror surface of 30 nmRy or less could be maintained (evaluation of surface roughness) This was carried out with a foam talissurf S4C manufactured by Taylor Hopson. Further, even when 10 glass disks were subsequently processed, no scratches were observed.

<Comparative example>
Using the same coating apparatus as in the above example, using only ZrO ₂ , a polishing tool was produced in the same manner as the polishing tool described in the prior art without adding magnetic particles to the polishing layer. Then, in the same manner as in the above example, 10 φ150 mm BK7 optical glass disks adjusted to a mirror surface having a surface roughness of about 30 nmRy were each processed in 3 minutes (processing conditions: platen rotation speed 60 rpm, processing pressure 30 kPa). ) However, although the mirror surface of 30 nmRy or less could be maintained, the occurrence of scratches as fine as 3 out of 10 processed disks was found.

  As can be seen from the comparison between this result and Examples 1 and 2, the abrasive grains and the workpieces are made to vibrate in a direction perpendicular to the processing surface. By shortening the contact time with the machined surface and minimizing the incision on the workpiece surface by the abrasive grains, it avoids sudden stress concentration due to variations in the grain size and hardness of the abrasive grains. It has been found that new processing damage can be suppressed, and high processing surface quality can be reliably obtained without sacrificing high processing efficiency.

  By including magnetic particles in the polishing layer of the polishing tool, the polishing tool can be vibrated perpendicularly to the processing surface. The present invention can be widely applied to a polishing apparatus, a polishing method, and the like using such a polishing tool.

It is sectional drawing of an abrasive | polishing tool, (A) has shown the case where an external magnetic field does not exist, (B) has shown the case where an external magnetic field exists. It is a figure explaining the case where it combines with a polishing tool and a patterned ferromagnetic material, (A) shows a patterned ferromagnetic material, (B) shows a polishing tool, a patterned ferromagnetic material, and It is sectional drawing of what combined. It is a figure explaining the production apparatus of an abrasive | polishing tool, (A) shows a top view, (B) shows sectional drawing. It is a figure explaining the use condition of the polish device using the polish tool of the present invention. It is a schematic diagram of the cross section after the conventional polishing tool process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Abrasive tool 2 Abrasive grain 3 Surface plate 4 Electromagnet 5 Wire bar 6 Work 11 Binder 12 Base material 21 Chips and worn abrasive grains 22 Magnetic fine particles 31 Patterned ferromagnetic material

Claims (11)

  A polishing tool that slides on a processed surface of a workpiece in contact with a polishing layer in which abrasive grains are fixed on a base material with a binder, and polishes the processed surface. A polishing tool comprising means for causing minute vibrations in a vertical direction with respect to a processing surface.   The polishing layer has second particles composed of magnetic particles in addition to the abrasive grains, and changes the external magnetic field to cause the polishing layer to vibrate in a direction perpendicular to the processing surface. The polishing tool according to claim 1, wherein   2. The polishing layer according to claim 1, wherein the polishing layer has abrasive grains made of magnetic particles and causes the polishing layer to vibrate in a direction perpendicular to the processing surface by changing an external magnetic field. The polishing tool according to 1.   3. The polishing tool according to claim 2, wherein in the polishing layer, the particle size of the second particles made of the magnetic particles is smaller than the particle size of the abrasive particles.   In the polishing layer, the second particles made of the magnetic particles are included in a binder that fixes the abrasive grains to the surface of the substrate, and the thickness of the binder that fixes the abrasive grains to the surface of the substrate is the abrasive grains. The polishing tool according to claim 2, wherein the polishing tool is smaller than the maximum diameter.   6. The polishing tool according to claim 1, wherein the abrasive grain content of the polishing layer is 10% by volume or more and 90% by volume or less.   A polishing tool that slides on a processed surface of a workpiece in contact with a polishing layer in which abrasive grains are fixed on a base material with a binder, and polishes the processed surface. A plurality of patterned ferromagnets having a fixed shape are embedded at intervals, and an electromagnet is disposed under the ferromagnet, and the external magnetic field is generated by the electromagnet. The polishing tool according to claim 2 or 3, characterized in that   The polishing tool according to claim 7, wherein the ferromagnetic material is soft magnetic and has a saturation magnetization of 0.8 Tesla or more.   A step of mixing magnetic particles with abrasive grains, a step of preparing a coating solution by adding a binder, and a magnetic field is generated in a direction perpendicular to the surface of the substrate in advance, and the coating is performed in an environment where a magnetic field exists. And a step of applying the liquid onto the substrate.   A polishing method in which abrasive grains are slid against a processed surface of a workpiece that is in contact with a polishing layer fixed with a binder on a base material, and the processed surface is polished. A large number of patterned ferromagnets having a fixed shape are embedded at intervals, and an electromagnet is disposed under the ferromagnet, and a magnetic field is generated by the electromagnet to change the magnetic field. Thus, the polishing method is characterized in that the polishing layer is vibrated minutely in a direction perpendicular to the processed surface.   A polishing apparatus comprising the polishing tool according to claim 7.