JP2006255809A - Polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing device with a polishing pad usable until reaching its life and easy to be exchanged. <P>SOLUTION: The polishing device 1 comprises a fixed plate 22 to which the polishing pad 24 is joined, and a polishing table 14 on which the fixed plate 22 is placed. The face of the polishing table 14 opposed to the fixed plate 22 and the face of the fixed plate 22 opposed to the polishing table 14 are formed to be smooth, and liquid 26 uniformly exists between the polishing table 14 and the fixed plate 22. In this construction, the surface tension of the liquid 26 works and the polishing table 14 is fixed to the fixed plate 22. Even if a polishing liquid permeates into the polishing pad 24, no ill effects are given between the fixed plate 22 and the polishing table 14 and therefor there is no need for exchanging the polishing pad 24 before reaching its life. When the polishing table 14 is fixed to the fixed plate 22, an adhesive such as a two-sided tape is not used. Thus, the polishing pad 24 is easy to be exchanged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing apparatus, and more particularly to a fixing means for fixing a polishing pad to a surface plate.

  When manufacturing a semiconductor device, a conductive film is formed on the surface of the wafer and a wiring layer is formed by photolithography, etching, or the like, or an interlayer insulating film is formed on the wiring layer. A process etc. are performed. By these steps, irregularities made of a conductor such as metal or an insulator are formed on the surface of the wafer. In recent years, miniaturization of wiring and multilayer wiring have been promoted for the purpose of increasing the density of semiconductor integrated circuits, and along with this, technology for flattening irregularities on the surface of a wafer has become important.

  In general, CMP (Chemical Mechanical Polishing) is employed as a method for flattening the unevenness on the surface of the wafer. CMP is a technique of polishing using a slurry-like polishing liquid in which abrasive grains are dispersed (hereinafter referred to as slurry) in a state where a surface to be polished of a wafer is pressed against a polishing surface of a polishing pad. A polishing apparatus generally used in CMP includes, for example, a polishing surface plate for supporting a polishing pad, a support base (polishing head) for supporting an object to be polished (wafer), and a backing for uniformly pressing the wafer. And a polishing liquid supply mechanism. The polishing pad is attached to the polishing surface plate by, for example, attaching with a double-sided tape (for example, Patent Document 1). The polishing surface plate and the support base are disposed so that the polishing pad supported by the polishing table and the object to be polished are opposed to each other, and each has a rotation shaft. In addition, a pressure mechanism for pressing the object to be polished against the polishing pad is provided on the support base side.

JP 2004-140215 A

  However, in a polishing apparatus that uses a polishing pad fixed to a surface plate by the above method, the polishing liquid that has passed through the polishing pad reaches the double-sided tape, and reduces the adhesiveness of the double-sided tape. For this reason, there is a problem that the polishing pad is easily peeled off, the flatness is lost on the surface of the polishing pad, and the polishing quality of the object to be polished cannot be maintained.

  In this case, it is necessary to remove the polishing pad from the polishing surface plate and replace it with a new double-sided tape. However, when the double-sided tape is peeled off from the polishing pad, it is difficult to apply a new double-sided tape to the polishing pad again because of the material of the polishing pad, and the polishing pad itself is also distorted. For this reason, although it can still be used as a polishing pad, it cannot be used again and is discarded.

  In addition, considerable time is required for the operation of attaching and detaching the polishing pad to and from the surface plate using the double-sided tape, for example, the attaching operation and the peeling operation. In particular, when the polishing pad is peeled off, the pressure-sensitive adhesive remains on the surface plate side, so that it takes a lot of man-hours and time to remove them.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a novel and easy-to-replace polishing pad that can use the polishing pad to the end of its life. An object is to provide an improved polishing apparatus.

  In order to solve the above-described problems, according to an aspect of the present invention, a polishing apparatus that chemically and mechanically polishes an object to be polished (for example, a semiconductor wafer) with a polishing pad, the fixing being fixed to the polishing pad. A surface plate (for example, a polishing table) on which the fixed plate is placed, and the surface of the fixed plate facing the surface plate and the surface of the surface plate facing the fixed plate are smooth surfaces. A polishing apparatus is provided in which the liquid is uniformly interposed between the fixing plate and the fixing plate to fix the fixing plate and the surface plate by the surface tension of the liquid.

  In such a polishing apparatus, when the polishing pad is fixed, an adhesive such as a double-sided tape is not used, and the polishing pad is fixed using the surface tension of a liquid such as water interposed between smooth surfaces facing each other. For this reason, the polishing pad is previously bonded to a fixing plate formed of a hard material such as alumina or a metal material such as stainless steel with an adhesive or the like so that the liquid to be interposed does not penetrate into the polishing pad. Then, by placing a fixed plate to which a polishing pad is bonded on a surface plate on which the liquid is uniformly applied, the surface tension of the liquid acts and the fixed plate and the surface plate can be fixed.

  Further, a porous material containing a liquid can be disposed between the fixed plate and the surface plate. As the porous material, for example, foamed urethane or foamed rubber material can be used. Such a porous material is formed into a sheet shape having a thickness of about 0.8 mm, for example, and is placed on the surface plate so as to uniformly cover the surface where the fixed plate and the surface plate are in contact with each other. Then, when a liquid is included in the placed porous material, the liquid is held uniformly. As a result, the surface tension works evenly, and the fixing plate and the surface plate can be fixed firmly and stably.

  Furthermore, a groove may be formed on at least one of the surface of the fixed plate facing the surface plate or the surface of the surface plate facing the fixed plate. This is because, when the fixed plate and the surface plate are fixed using the surface tension of the liquid, if air stays between the fixed plate and the surface plate, bubbles are generated on the liquid surface, and the surface The tension cannot be applied. Therefore, by forming the groove, it is possible to promote the action of eliminating air.

  Further, when the fixed plate is placed on the surface plate, it can be installed so that the engaging portion provided on the surface plate engages with the engaged portion provided on the fixed plate. With this configuration, the polishing pad bonded to the fixing plate can be fixed so as not to rotate on the surface plate.

  As described above, according to the present invention, it is possible to provide a polishing apparatus in which the polishing pad can be used up to the end of its life and the polishing pad can be easily replaced.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, a polishing apparatus according to this embodiment will be described with reference to FIG. Here, FIG. 1 is a perspective view showing the polishing apparatus according to the present embodiment.

  As shown in FIG. 1, the polishing apparatus 1 according to the present embodiment includes, for example, a polishing pad fixing unit 10, a polishing pad 24, a substrate holding unit 30, and a polishing liquid supply unit 40. .

  The polishing pad fixing means 10 includes, for example, a motor 12, a spindle 13, and a polishing table 14. The polishing table 14 is a substantially disk-shaped surface plate formed of, for example, stainless steel or ceramics, and has a smooth horizontal surface on the upper surface. The polishing table 14 rotates at a predetermined speed in the horizontal direction (the direction of the thick arrow in FIG. 1), for example, when the driving force of the motor 12 is transmitted through the spindle 13 or the like.

  The polishing pad 24 is formed of a material that holds a polishing liquid. For example, a polishing pad used when using a polishing liquid containing loose abrasive grains, a fixed abrasive pad containing fixed abrasive grains in the polishing pad, or the like is used. Can be used. The polishing pad 24 is bonded to the fixed plate 22 with an adhesive such as tape or glue. The fixing plate 22 is made of, for example, a hard material such as alumina, PVC (Polyvinyl Chloride), PE (Polyethylene), bakelite, FRP (Fiber Reinforced Plastic), or a metal such as stainless steel or aluminum. The surface of the fixing plate 22 facing the polishing table 14 is a smooth surface. As described above, the fixing plate 22 to which the polishing pad 24 is bonded is placed on the polishing table 14.

  The substrate holding unit 30 includes, for example, a substrate holding unit driving unit 32 and a substrate holding unit 34. The substrate holding unit driving unit 32 is configured to include a rotation mechanism (not shown) such as a rotary motor and a pressure mechanism (not shown) such as a cylinder. The substrate holding part 34 is a polishing head having a substantially disk shape, for example, and has a vacuum chuck mechanism (not shown). By this vacuum chuck mechanism, the semiconductor wafer 50 as the workpiece can be sucked and held on the lower surface side of the substrate holding portion 34. In addition, a retainer ring 35 for holding the outer periphery of the semiconductor wafer 50 can be provided on the outer edge portion on the lower surface side of the substrate holding portion 34, thereby preventing a lateral shift of the semiconductor wafer 50. The substrate holding unit 34 is supported by, for example, the substrate holding unit driving unit 32 via the rod 33, and is rotated in the direction of the thin arrow of FIG. Is raised and lowered.

  The polishing liquid supply means 40 includes, for example, a polishing liquid supply nozzle 42. The polishing liquid supply nozzle 42 supplies the polishing liquid 44 onto the polishing pad 24 during polishing. As the polishing liquid 44, for example, a slurry containing abrasive grains or an alkaline solution not containing abrasive grains is used. After supplying the polishing liquid 44 from the polishing supply nozzle 42 onto the polishing pad 24, the polishing liquid 44 enters between the surface to be polished of the semiconductor wafer 50 and the surface of the polishing pad 24 with the rotation of the polishing pad 24. The surface to be polished is chemically polished.

  The configuration of the polishing apparatus 1 according to the present embodiment has been described above. Next, the polishing pad fixing means 10 for fixing the polishing pad 24 to the polishing table 14, which is a feature of the present invention, will be described with reference to FIG. FIG. 2 is a partial cross-sectional view showing the polishing pad fixing means 10 and the polishing pad 24 according to the present embodiment.

  In the polishing apparatus 1 according to this embodiment, the surface tension of the liquid is used to fix the polishing pad 24 to the polishing table 14. Specifically, as shown in FIG. 2, the polishing pad fixing means 10 according to the present embodiment includes a polishing table 14 that is a surface plate, and a fixing plate 22 is provided on the polishing table 14. The liquid 26 is uniformly supplied to the entire surface on which is placed. Then, the fixing plate 22 to which the polishing pad 24 is bonded is placed on the polishing table 14 to which the liquid 26 is supplied.

  Here, conventionally, the polishing table 14 and the polishing pad 24 are fixed with, for example, a tape or the like. On the other hand, in the polishing apparatus 1 according to the present embodiment, since the surface tension of the liquid 26 is used for fixing, the liquid 26 is polished when the polishing pad 24 is placed directly on the polishing table 14 to which the liquid 26 is supplied. It penetrates into the pad 24 and the surface tension of the liquid 26 cannot be used. Further, if the installation surface of the object to be fixed and the mounting surface of the object to be fixed are not smooth surfaces, the surface tension does not work even if the liquid 26 is interposed. Therefore, the fixing plate 22 made of a material that does not penetrate the liquid 26 and can form a smooth surface is joined to the surface of the polishing pad 24 facing the polishing table 14. For the liquid 26, for example, water, polishing liquid, water-soluble resin, or the like can be used.

  When the fixing plate 22 to which the polishing pad 24 is bonded is placed and fixed on the polishing table 14, first, the liquid 26 is uniformly supplied to the entire surface of the polishing table 14 facing the fixing plate 22. Next, the fixing plate 22 to which the polishing pad 24 is bonded is placed on the polishing table 14 and fixed by the surface tension of the liquid 26. When the object to be polished is polished in this way, the polishing liquid 44 may be mixed between the surface of the fixed plate 22 facing the polishing table 14 and the surface of the polishing table 14 facing the fixed plate 22. However, since the polishing liquid 44 has a surface tension as a liquid, there is no problem in use.

  The polishing apparatus 1 according to the first embodiment has been described above. With such a configuration, the polishing pad 24 and the polishing table 14 can be fixed without using an adhesive such as a tape. Therefore, the polishing pad 24 can be easily replaced, and the polishing pad 24 can be used until the end of its life.

  Next, as a modification of the polishing pad fixing means 10 of the polishing apparatus 1 according to the first embodiment, a polishing apparatus according to the second embodiment will be described with reference to FIGS. Here, FIG. 3 is a partial cross-sectional view showing the polishing pad fixing means 10 and the polishing pad 24 according to the second embodiment. 4A is a perspective view of the polishing pad fixing means 10 of FIG. 3 on which the polishing pad is placed, and FIG. 4B is a polishing pad fixing means 10 on which the polishing pad is placed. It is a perspective view which shows the modification of this. FIG. 5 is a bottom view showing the fixing plate 22 according to the second embodiment. In the polishing apparatus according to the second embodiment, the configuration other than the polishing pad fixing means 10, the fixing plate 22, and the polishing pad 24 is the same as that of the polishing apparatus 1 according to the first embodiment. Description is omitted.

(Second Embodiment)

  The polishing apparatus according to the second embodiment is fixed to the surface 14b (smooth surface 14b) facing the fixing plate 22 of the polishing table 14 in order to hold the liquid 26 supplied onto the polishing table 14 more uniformly. In the first embodiment, a porous sheet 27 formed of a porous material containing a liquid 26 is disposed between the surface 22b (smooth surface 22b) of the plate 22 facing the polishing table 14. This is different from the polishing apparatus 1. The porous sheet 27 is made of, for example, foamed urethane, foamed rubber material, or the like, and has a thickness of about 0.8 mm, for example. By including the liquid in such a porous sheet 27, the liquid can be uniformly supplied to the mounting surface of the fixed plate 22 on the polishing table 14.

  Further, when the fixing plate 22 with the polishing pad 24 bonded thereto is fixed to the polishing table 14, for example, as shown in FIGS. 3 and 4A, the periphery of the fixing plate 22 is placed around the outer edge of the polishing table 14. You may install the guide 17 so that it may surround. The guide 17 is formed from, for example, vinyl chloride or the like, and has a height of, for example, about 1 to 2 mm. By installing such a guide 17, positioning when the fixed plate 22 is placed on the polishing table 14 is facilitated. In addition, the guide 17 can prevent the liquid contained in the porous sheet 27 interposed between the smooth surface 14b and the smooth surface 22b from being discharged to the outer edge side of the polishing table. The guide 17 and the porous sheet 27 need not be replaced when the polishing pad 24 is replaced.

  Further, as shown in FIG. 3, a liquid exclusion through-hole 15 may be provided under the polishing table 14 so that the polishing pad 24 can be easily replaced even when the guide 17 is installed. it can. With this configuration, when the polishing pad 24 is replaced, the fixing plate 22 to which the polishing pad 24 is bonded can be easily removed by discharging the liquid between the smooth surface 14b and the smooth surface 22b to reduce the pressure. Can be. Normally, when the polishing process is performed, the liquid contained in the porous sheet 27 can be prevented from being excluded by closing the through hole 15 with, for example, the bolt 16.

  Further, when polishing with the polishing pad 24, there is a possibility that the fixing plate 22 to which the polishing pad 24 is bonded is rotated on the polishing table 14 due to frictional force with the semiconductor wafer 50 that is the object to be polished. In order to prevent this, for example, a member for preventing rotation may be provided on the fixing plate 22 to which the polishing pad 24 is bonded. As a member for preventing this rotation, for example, as shown in FIG. 4B, for example, three engaging portions 22a are formed on a part of the fixed plate 22 so as to protrude to the outer peripheral side. Then, an engaged portion 17 a that engages with the engaging portion 22 a is formed in the guide 17 installed on the polishing table 14. With this structure, the fixing plate 22 to which the polishing pad 24 is bonded can be fixed on the polishing table 14 so as not to rotate during polishing.

  Further, in order to increase the surface tension of the liquid, for example, a groove 23 is formed on at least one of the surface 14b of the polishing table 14 facing the fixed plate 22 or the surface 22b of the fixed plate 22 facing the polishing table 14. Is good. This is a groove for removing air between the liquid and the fixing plate 22 and the polishing table 14 when the fixing plate 22 and the polishing table 14 are fixed with the liquid interposed. If air stays between the liquid and the smooth surface 22b and the smooth surface 14b, bubbles are generated on the surface of the liquid, and the surface tension of the liquid cannot be fully utilized. Therefore, by forming the groove 23, the action of eliminating air is promoted. The shape of the groove 23 can be formed so as to spread radially from the center, for example, as shown in FIG.

  The second embodiment has been described above. In the polishing apparatus 1 according to the second embodiment, the liquid supplied onto the polishing table 14 is included in the porous sheet 27 so that the liquid can be held uniformly and the surface tension can be applied evenly. it can. Further, the guide 17 is installed on the polishing table 14 so that the polishing pad 24 can be easily positioned, and the liquid on the polishing table 14 can be prevented from being removed. Further, by engaging the engaging portion 22 a formed on the fixed plate 22 with the engaged portion 14 b formed on the polishing table 14 and placing the fixed plate 22 on the polishing table 14, the fixed plate 22. Can be fixed so as not to rotate on the polishing table 14.

  Next, in order to verify the effect of the polishing apparatus according to the present invention, the following two experiments were conducted. In the experiment, the polishing apparatus according to the second embodiment and the conventional polishing apparatus were used to measure and compare the durability of the polishing pad and the time required to replace the polishing pad.

  First, the polishing apparatus used in Experiment 1 and Experiment 2 will be described. The polishing apparatus according to the second embodiment includes a porous sheet containing a liquid in the polishing table 14 constituting the polishing pad fixing means 10 of the polishing apparatus. 27, and a fixing plate 22 to which a polishing pad 24 not containing an abrasive was bonded was placed thereon. On the other hand, the conventional polishing apparatus is different from the polishing apparatus according to the second embodiment in that the polishing pad is fixed to the polishing table with double-sided tape, and the other configuration is the same.

Using these two polishing apparatuses, while pressing the semiconductor wafer as the object to be polished against the polishing pad and supplying the polishing liquid between the polishing pad and the semiconductor wafer, The semiconductor wafer was polished by the relative motion of. In this polishing process, the polishing pressure was set to 300 g / cm ² , and the rotation speed of the polishing table 14 was set to 40 rpm.

(Experiment 1: Comparison of polishing pad durability)
In Experiment 1, the durability of the polishing pad, that is, the number of days from the start of use of the polishing pad until it became necessary to be replaced was measured. Here, the state in which it is determined that the polishing pad needs to be replaced means, for example, a state in which the polishing pad is peeled off from the polishing table and the flatness cannot be maintained on the surface of the polishing pad.

  As shown in Table 1, when the conventional polishing apparatus was used, the polishing pad could be used continuously after 30 days, but when 60 days passed, the polishing pad was fixed to the polishing table. The adhesive force of the adhesive layer to be lowered decreased, and the polishing pad was peeled off. When the polishing pad is peeled off, it greatly affects the polishing quality such as the polishing rate and flatness, and therefore the polishing pad needs to be replaced. On the other hand, when the polishing apparatus according to the second embodiment is used, the polishing liquid 44 that has penetrated the polishing pad 24 reaches the adhesive layer because it does not have an adhesive layer that adheres the fixing plate 22 and the polishing table 14. Thus, the adhesive strength of the adhesive layer is not reduced. Therefore, the fixing plate 22 to which the polishing pad 24 is bonded is not peeled off from the polishing table 14, so that it is not necessary to replace the polishing pad 24 even after 90 days from the start of use.

  As described above, when the polishing apparatus according to the second embodiment is used, since the fixing plate 22 to which the polishing pad 24 is bonded is fixed using the surface tension of the liquid, the polishing pad is fixed with the conventional double-sided tape. Compared to the case, it can be used three times or more, and the durability of the polishing pad is improved. Since the durability of the polishing pad is considered to vary depending on the use conditions of the polishing pad, the above results do not apply to all polishing pads. However, when the polishing pad fixing means according to the present invention is compared with the conventional fixing means, it is considered that the durability is excellent in principle.

(Experiment 2: Comparison of polishing pad replacement time)
Next, in Experiment 2, the time required to replace the polishing pad was compared. The replacement of the polishing pad includes a peeling operation for peeling the polishing pad from the polishing table, a surface plate cleaning operation for cleaning the mounting surface of the polishing table on which the polishing pad is placed, and a new polishing pad attached to the polishing table. And pasting work. Table 2 shows the time required for each operation.

  As shown in Table 2, the time required to replace the polishing pad in the conventional polishing apparatus was about 80 minutes in total. On the other hand, in the polishing apparatus according to the second embodiment, the time required to replace the polishing pad was about 20 minutes in total. Also, for each operation, the operation time is reduced to about 1/4 compared to the case where a conventional polishing apparatus is used. From this, it was found that when the polishing apparatus 1 according to the second embodiment is used, the time required for replacing the polishing pad can be shortened to about ¼ compared to the conventional case.

  Thus, when the polishing apparatus according to the second embodiment is used, the adhesive plate is not used because the fixing plate 22 to which the polishing pad 24 is bonded is fixed using the surface tension of the liquid. It can be seen that the time required to replace the polishing pad can be shortened as compared with the case where the polishing pad is fixed with the conventional double-sided tape. Therefore, the operation time of the polishing apparatus is increased, and the productivity of the polishing apparatus as a whole can be improved.

  In Experiments 1 and 2, the polishing pad of the polishing apparatus according to the second embodiment was tested with respect to a polishing pad that does not include an abrasive and a fixed abrasive pad that includes an abrasive. There was no difference in results.

  As described above, from Experiment 1 and Experiment 2, when the polishing apparatus according to the second embodiment is used, the frequency of replacing the polishing pad can be reduced, and the time required for replacing the polishing pad can be shortened. It was shown that it can be done. Therefore, the life of the polishing pad can be extended, and the productivity of the polishing apparatus as a whole can be increased by increasing the operating time of the polishing apparatus.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are of course within the technical scope of the present invention. Understood.

  For example, the engaging portion 22a formed on the fixing plate 22 according to the second embodiment is three protrusions, but the present invention is not limited to this example, and the engaged portion formed on the guide 17 The number and the shape are not limited as long as the polishing pad 24 can be fixed so as not to rotate by engaging with the portion 17a. For example, the engaging portion 22a may be engaged with the concave portion, and the engaged portion 17a formed on the guide 17 may be formed with the convex portion.

  Further, although the guide 17 according to the second embodiment is installed on the polishing table 14, the present invention is not limited to such an example. For example, the outer periphery of the fixing plate 22 to which the polishing pad 24 is bonded is extended. Thus, a guide can be installed so as to cover the outer peripheral portion of the polishing table 14.

  Furthermore, although the shape of the groove | channel 23 concerning 2nd Embodiment is radial form, this invention is not limited to this example, For example, it can also form in grid | lattice form, cyclone form, concentric circle form, spiral form, etc. .

  Further, the polishing apparatus according to the second embodiment includes a porous sheet 27, a guide 17, an engaging portion 17a formed on the guide 17, an engaged portion 22a formed on the fixed plate 22, and a groove 23. However, the present invention is not limited to such an example. By installing at least one of the polishing apparatus 1 according to the first embodiment, the function of the surface tension of the liquid, etc. Can be further improved.

  The present invention is applicable to a polishing apparatus, and particularly applicable to a fixing means for fixing a polishing pad to a surface plate.

1 is an overall perspective view showing a polishing apparatus according to a first embodiment of the present invention. It is a fragmentary sectional view of the polishing pad fixing means and polishing pad of the polisher concerning the above-mentioned embodiment. It is a fragmentary sectional view of a polishing pad fixing means and a polishing pad of a polisher concerning a 2nd embodiment of the present invention. (A) is a perspective view of the polishing pad fixing means of FIG. 3 on which the polishing pad is placed, and (b) is a perspective view showing a modification of the polishing pad fixing means on which the polishing pad is placed. is there. It is a bottom view which shows the fixing plate concerning the said embodiment.

Explanation of symbols

1 Polishing device 14 Surface plate (polishing table)
DESCRIPTION OF SYMBOLS 15 Through-hole 16 Nut 17 Guide 22 Fixing plate 23 Groove 24 Polishing pad 26 Liquid 27 Porous sheet 50 Semiconductor wafer

Claims (4)

A polishing apparatus for chemically and mechanically polishing an object to be polished with a polishing pad,
A fixing plate to which the polishing pad is bonded;
A surface plate on which the fixed plate is placed;
With
The surface of the surface plate facing the fixed plate and the surface of the fixed plate facing the surface plate are smooth surfaces,
The polishing apparatus, wherein the surface plate and the fixed plate are fixed by surface tension of the liquid by uniformly interposing a liquid between the surface plate and the fixed plate.   2. The polishing apparatus according to claim 1, wherein a porous material containing the liquid is disposed between the surface plate and the fixed plate.   3. The groove according to claim 1, wherein a groove is formed on at least one of a surface of the surface plate facing the fixed plate and a surface of the fixed plate facing the surface plate. 4. A polishing apparatus according to claim 1. When placing the fixed plate on the surface plate,
The polishing pad is fixed so as not to rotate on the surface plate by engaging an engaging portion provided on the surface plate and an engaged portion provided on the fixing plate. The polishing apparatus according to any one of claims 1 to 3.

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