JP5378971B2 - Polishing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing device which can perform electrolytic polishing to a workpiece without complicating a carrying mechanism carrying the workpiece to a workpiece holding means. <P>SOLUTION: In the polishing device, a polisher polishing a workpiece held to a chuck table 81 is composed of: a rotary spindle 322; a wheel mount 4; and a polishing wheel 5. The polishing wheel includes: a wheel base 51 whose upper face is mounted to the lower face of the wheel mount; and a polishing pad 52 mounted to the lower face of the wheel base and provided with a plurality of electrolyte flowout holes. The wheel base includes a plus electrode plate 53 and a minus electrode plate 54 provided with a plurality of communication holes 541 communicated with the plurality of electrolyte flowout holes 522 provided at the polishing pad, further, an electrolyte introduction passage 512 communicated with the plurality of communication holes is provided, and the wheel mount is provided with a communication passage communicating the electrolyte introduction passage provided at the wheel base with the electrolyte feed passage provided at the rotary spindle. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a polishing apparatus for polishing a workpiece such as a semiconductor wafer.

  In the semiconductor device manufacturing process, a large number of rectangular areas are defined by cutting lines called streets arranged in a lattice pattern on the surface of a semiconductor wafer having a substantially disk shape, and devices such as ICs, LSIs, etc. are divided into the rectangular areas. Form. Individual devices are formed by dividing the semiconductor wafer on which a large number of devices are formed in this manner along the streets. In order to reduce the size and weight of the device, the semiconductor wafer is usually ground to the predetermined thickness by grinding the backside of the semiconductor wafer before it is cut along the street and divided into individual devices. . Grinding of the back surface of a semiconductor wafer is usually performed by pressing a grinding wheel having a grinding wheel formed by fixing diamond abrasive grains with an appropriate bond such as a resin bond against the back surface of the semiconductor wafer while rotating. ing. When the back surface of the semiconductor wafer is ground by such a grinding method, so-called processing strain is generated on the back surface of the semiconductor wafer, thereby reducing the bending strength of the individually divided devices.

  As a measure for removing the processing strain generated on the back surface of the ground semiconductor wafer as described above, polishing is performed using a polishing pad while supplying a polishing liquid to the back surface of the ground semiconductor wafer, and the back surface of the semiconductor wafer is A method for removing the generated processing strain is disclosed in Patent Document 1 below.

  However, a through hole (via hole) that reaches the back surface is formed at a position where the bonding pad formed on the surface of the device is provided, and a metal electrode such as copper connected to the bonding pad is embedded in the through hole (via hole). In the constructed wafer, a metal film is laminated on the back surface in order to embed a metal electrode by depositing a conductive material such as copper from the back surface side of the wafer. For this reason, when the back surface of the wafer is polished by the polishing method disclosed in Patent Document 1 in order to expose the metal electrode from the back surface of the wafer, the polishing pressure by the polishing pad is high, so that the metal electrode exposed on the back surface of the wafer is recessed. This causes a problem that the upper and lower electrodes cause poor contact when the devices are stacked.

  On the other hand, Patent Document 2 below discloses an electropolishing apparatus that performs polishing while reducing the polishing pressure. The electrolytic polishing apparatus includes a polishing table on which a processing electrode and a polishing pad are disposed, and a polishing head that holds a workpiece, and the polishing head supplies an electrolytic solution onto the polishing pad of the rotating polishing table. By pressing the workpiece held on the polishing pad while rotating, the workpiece is electropolished.

JP-A-8-99265 JP 2009-108405 A

  Thus, the electropolishing apparatus disclosed in Patent Document 2 has a configuration in which a polishing pad is disposed on a polishing table and the workpiece is held on the polishing head, so that the workpiece is placed on the lower surface of the polishing head. There is a problem in that the transport mechanism for transporting and holding is complicated.

  The present invention has been made in view of the above facts, and a main technical problem thereof is a polishing apparatus capable of performing electrolytic polishing without complicating a transport mechanism for transporting a workpiece to a workpiece holding means. Is to provide.

In order to solve the above main technical problem, according to the present invention, there is provided a chuck table configured to hold and rotate a workpiece, and a polishing means for polishing the workpiece held on the chuck table. In the polishing apparatus, the polishing means comprises a rotating spindle, a wheel mount provided at the lower end of the rotating spindle, and a polishing wheel detachably attached to the lower surface of the wheel mount.
The polishing wheel includes a wheel base having an upper surface mounted on the lower surface of the wheel mount, and a polishing pad mounted on the lower surface of the wheel base and having a plurality of electrolyte outflow holes. Includes a positive electrode plate having a plurality of communication holes communicating with a plurality of electrolyte outflow holes provided in the polishing pad and an electrolyte solution communicating with the plurality of communication holes. There is an introduction passage,
The wheel mount includes a communication path that connects an electrolyte introduction path provided in the wheel base and an electrolyte supply path provided in the rotary spindle;
Comprising power supply means for applying a voltage between the positive electrode plate and the negative electrode plate;
A polishing apparatus is provided.

  The wheel base of the grinding wheel is provided with a positive electrode terminal and a negative electrode terminal that are respectively connected to the positive electrode plate and the negative electrode plate and project from the upper surface, and the wheel mount includes the power supply means. Are connected to the positive electrode terminal and the negative electrode terminal, respectively.

  The polishing apparatus according to the present invention attaches the polishing wheel to the wheel mount provided at the lower end of the rotating spindle as described above, and electrolyzes the workpiece held on the chuck table while supplying an electrolytic solution to the polishing wheel. Since it is configured to polish, it is easy to load and unload the workpiece onto and from the chuck table, and the mechanism for loading and unloading the workpiece to and from the chuck table can be made relatively simple.

1 is a perspective view of a polishing apparatus configured according to the present invention. The perspective view which shows the state which looked at the wheel mount which comprises the grinding | polishing apparatus shown in FIG. 1 from the downward direction. The perspective view of the grinding | polishing wheel which comprises the grinding | polishing apparatus shown in FIG. Explanatory drawing which shows the arrangement | sequence state of the electrode with which the wheel base which comprises the grinding | polishing wheel shown in FIG. 3 was mounted | worn. Sectional drawing which shows the state by which the grinding | polishing wheel shown in FIG. 3 was mounted | worn with the wheel mount shown in FIG. Explanatory drawing which shows the state which grind | polishes a workpiece by the grinding | polishing apparatus shown in FIG.

  Preferred embodiments of a polishing apparatus constructed according to the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a polishing apparatus constructed according to the present invention.
The polishing apparatus comprises an apparatus housing, generally designated 2. The apparatus housing 2 has a rectangular parallelepiped main portion 21 that extends elongated and an upright wall 22 that is provided at the rear end portion (upper right end in FIG. 1) of the main portion 21 and extends upward. A pair of guide rails 221 and 221 extending in the vertical direction are provided on the front surface of the upright wall 22. The pair of guide rails 221 and 221 is mounted with a polishing unit 3 as a polishing means so as to be movable in the vertical direction.

  The polishing unit 3 includes a moving base 31 and a spindle unit 32 attached to the moving base 31. The movable base 31 is provided with a pair of legs 311 and 311 extending in the vertical direction on both sides of the rear surface. The pair of legs 311 and 311 is slidably engaged with the pair of guide rails 221 and 221. Guided grooves 312 and 312 are formed. As described above, a support portion 313 protruding forward is provided on the front surface of the movable base 31 slidably mounted on the pair of guide rails 221 and 221 provided on the upright wall 22. The spindle unit 32 is attached to the support portion 313.

  The spindle unit 32 includes a spindle housing 321 mounted on the support portion 313, a rotating spindle 322 rotatably disposed on the spindle housing 321, and a servo as rotation driving means for driving the rotating spindle 322 to rotate. And a motor 323. The lower end of the rotary spindle 322 protrudes downward beyond the lower end of the spindle housing 321, and a disc-shaped wheel mount 4 is provided at the lower end. A polishing wheel 5 is detachably attached to the lower surface of the wheel mount 4. The wheel mount 4 and the grinding wheel 5 will be described with reference to FIGS.

2 is a perspective view of the wheel mount 4 as viewed from below, FIG. 3 is a perspective view of the grinding wheel 5, and FIG. 4 is an array of electrodes mounted on a wheel base constituting the grinding wheel 5 shown in FIG. FIG. 5 is a cross-sectional view showing a state where the grinding wheel 5 is mounted on the wheel mount 4.
The wheel mount 4 is formed in a disk shape as shown in FIGS. 2 and 5, and is provided at the lower end of the rotary spindle 322. As shown in FIG. 2, the wheel mount 4 is provided with four bolt insertion holes 41 at intervals in the circumferential direction. As shown in FIG. 5, the wheel mount 4 is provided with a communication passage 42 that communicates with an electrolyte supply passage 322a provided in the rotary spindle 322 and opens on the lower surface (mounting surface). As shown in FIG. 2, four of the communication passages 42 are opened on the lower surface (mounting surface). The wheel mount 4 is provided with four cylindrical positive electrode plugs 43 and two cylindrical negative electrode plugs 44.

  As shown in FIG. 3, the polishing wheel 5 includes a wheel base 51 formed in a disk shape and a polishing pad 52 mounted on the lower surface of the wheel base 51. The wheel base 51 is provided with four female screw holes 511 at intervals in the circumferential direction at positions corresponding to the four bolt insertion holes 41 provided in the wheel mount 4. Further, as shown in FIGS. 3 and 5, the wheel base 51 is provided with an electrolyte introduction passage 512 that communicates with the communication passage 42 provided in the wheel mount 4. The electrolytic solution introduction passage 512 is provided to open at a position corresponding to the communication passage 42 provided in the wheel mount 4 on the upper surface of the wheel base 51. As shown in FIGS. 4 and 5, four positive electrode plates 53 and four negative electrode plates 54 are mounted on the lower surface of the wheel base 51. The four plus electrode plates 53 and the four minus electrode plates 54 are disposed at positions corresponding to the electrolyte solution introduction passages 512 provided in the wheel base 51 and communicate with the electrolyte solution introduction passages 512, respectively. A plurality of communication holes 531 and 541 are provided. The wheel base 51 is provided with four positive electrode terminals 55 and two negative electrode terminals 56 protruding from the upper surface as shown in FIG. The four plus electrode terminals 55 are configured to be fitted with four cylindrical plus electrode plugs 43 disposed on the wheel mount 4, and the two minus electrode terminals 56 are arranged on the wheel mount. 4 is configured to be fitted with two cylindrical negative electrode plugs 44 disposed in the cylinder 4. The four positive electrode terminals 55 configured in this way are connected to the four positive electrode plates 53 by conducting wires (not shown), and the two negative electrode terminals 56 are two of the four negative electrode plates 54. They are connected to each other by conductors (not shown).

  The polishing pad 52 mounted on the lower surface of the wheel base 51 configured as described above is formed of urethane. As shown in FIG. 5, the polishing pad 52 includes a plurality of communication grooves 521 that communicate with the communication holes 531 provided in the plus electrode plate 53 and the communication holes 541 provided in the minus electrode plate 54 on the upper surface, A plurality of electrolyte outflow holes 522 communicating with the communication groove 521 and opening on the lower surface are provided.

  The wheel mount 4 and the grinding wheel 5 are configured as described above, and the wheel base 51 of the grinding wheel 5 is positioned on the lower surface (mounting surface) of the wheel mount 4 and four pluses provided on the wheel base 51 are provided. The electrode terminal 55 is fitted into four cylindrical positive electrode plugs 43 provided on the wheel mount 4, and the two negative electrode terminals 56 provided on the wheel base 51 are provided on the wheel mount 4. The two cylindrical negative electrode plugs 44 are fitted. Then, the fastening bolt 55 (see FIG. 5) is inserted into the bolt insertion hole 41 provided in the wheel mount 4 and screwed into the female screw hole 511 provided in the wheel base 51 of the grinding wheel 5, whereby FIG. As shown in FIG. 3, the polishing wheel 5 can be mounted on the lower surface (mounting surface) of the wheel mount 4.

  Continuing with reference to FIG. 5, the polishing apparatus in the illustrated embodiment includes power supply means 6 for applying a voltage between the four positive electrode plates 53 and the four negative electrode plates 54. doing. The power supply means 6 includes four DC power supplies 61a, 61b, 61c, 61d. On the other hand, five slip rings 62a, 62b, 62c, 62d, and 62e are disposed on the outer peripheral surface of the upper end portion of the rotary spindle 322, and among these, four slip rings 62a, 62b, 62c, and 62d are arranged as described above. Four DC power supplies 61a, 61b, 61c, 61d are connected to the plus (+) side, and one slip ring 62e is connected to the four DC power supplies 61a, 61b, 61c, 61d on the minus (−) side. The The four slip rings 62a, 62b, 62c, 62d are respectively connected to four cylindrical positive electrode plugs 43 disposed on the wheel mount 4 by conducting wires (not shown). The ring 62e is connected to two cylindrical negative electrode plugs 44 disposed on the wheel mount 4 by a lead wire (not shown). Therefore, when the power supply means 6 is activated, the DC power sources 61a, 61b, 61c, 61d to the slip rings 62a, 62b, 62c, 62d, the conductors not shown, the four positive electrode plugs 43, the four positive electrode terminals 55, A voltage is applied between the four positive electrode plates 53 and the four negative electrode plates 54 via a lead wire (not shown).

  The electrolyte supply passage 322a provided with the rotary spindle 322 is in communication with the electrolyte supply means 9 as shown in FIG. Therefore, when the electrolyte supply means 9 is operated, for example, an electrolyte containing citric acid and abrasive grains is supplied to the electrolyte supply passage 322a, the communication passage 42 provided in the wheel mount 4, and the electrolytic provided in the wheel base 51. Through the plurality of communication grooves 521 provided in the polishing pad 52 through the liquid introduction passage 512, the communication holes 531 provided in the positive electrode plate 53, and the communication holes 541 provided in the negative electrode plate 54, a plurality of electrolytes flow out. It flows out of the hole 522.

  Referring back to FIG. 1, the polishing apparatus in the illustrated embodiment moves the polishing unit 3 in the vertical direction along the pair of guide rails 221 and 221 (in a direction perpendicular to the holding surface of the chuck table described later). A polishing feed means 7 is provided for moving to the right. The polishing feed means 7 includes a male threaded rod 71 disposed on the front side of the upright wall 22 and extending in the vertical direction. The male screw rod 71 is rotatably supported by bearing members 72 and 73 whose upper end and lower end are attached to the upright wall 22. The upper bearing member 72 is provided with a pulse motor 74 as a drive source for rotationally driving the male screw rod 71, and an output shaft of the pulse motor 74 is transmission-coupled to the male screw rod 71. A connecting portion (not shown) that protrudes rearward from the center portion in the width direction is also formed on the rear surface of the movable base 31, and a through female screw hole extending in the vertical direction is formed in this connecting portion, The male screw rod 71 is screwed into the female screw hole. Accordingly, when the pulse motor 74 rotates in the forward direction, the moving base 31, that is, the polishing unit 3 is lowered or moved forward, and when the pulse motor 74 rotates in the reverse direction, the moving base 31, that is, the polishing unit 3 is raised or moved backward.

  Continuing the description with reference to FIG. 1, the chuck table mechanism 8 is disposed in the main portion 21 of the housing 2. The chuck table mechanism 8 includes a chuck table 81 as a workpiece holding means, a cover member 82 that covers the periphery of the chuck table 81, and bellows means 83 and 84 that are disposed before and after the cover member 82. ing. The chuck table 81 is configured to be rotated by a rotation drive mechanism (not shown), and is configured to suck and hold a wafer as a workpiece on its upper surface by operating a suction means (not shown). Further, the chuck table 81 is moved between a workpiece placement area 24 shown in FIG. 1 and a polishing area 25 facing the polishing wheel 51 constituting the polishing unit 3 by a chuck table moving means (not shown). The bellows means 83 and 84 can be formed from any suitable material such as campus cloth. The front end of the bellows means 83 is fixed to the front wall of the main portion 21, and the rear end is fixed to the front end surface of the cover member 82. The front end of the bellows means 84 is fixed to the rear end surface of the cover member 82, and the rear end is fixed to the front surface of the upright wall 22 of the apparatus housing 2. When the chuck table 81 is moved in the direction indicated by the arrow 23a, the bellows means 83 is expanded and the bellows means 84 is contracted. When the chuck table 81 is moved in the direction indicated by the arrow 23b, the bellows means 83 is By contracting, the bellows means 84 is extended.

  The description will be continued based on FIG. 1. On the front half of the main portion 21 of the apparatus housing 2, a first cassette 11, a second cassette 12, a workpiece temporary placing means 13, and a cleaning means are provided. 14, a workpiece conveying means 15, a workpiece carrying-in means 16 and a workpiece carrying-out means 17 are arranged. The first cassette 11 stores a workpiece before polishing and is placed in a cassette carry-in area in the main portion 21 of the apparatus housing 2. A plurality of semiconductor wafers W are accommodated in the cassette 11 in a state where the protective tape T is adhered to the surface. At this time, the semiconductor wafer W is accommodated with the back surface (surface to be ground) facing upward. The second cassette 12 is placed in a cassette unloading area in the main portion 21 of the apparatus housing 2 and accommodates the semiconductor wafer W after polishing. The workpiece temporary mounting means 13 is disposed between the first cassette 11 and the workpiece loading / unloading area 24, and temporarily mounts the semiconductor wafer W before polishing. The cleaning means 14 is disposed between the workpiece loading / unloading area 24 and the second cassette 12, and cleans the semiconductor wafer W after polishing. The workpiece transport means 15 is disposed between the first cassette 11 and the second cassette 12, and the semiconductor wafer W stored in the first cassette 11 is placed on the workpiece temporary placement means 13. The semiconductor wafer W that has been unloaded and cleaned by the cleaning means 14 is transferred to the second cassette 12. The workpiece carrying-in means 16 is disposed between the workpiece temporary placing means 13 and the workpiece carrying-in / out area 24 and is placed on the workpiece temporary placing means 13 before polishing. The semiconductor wafer W is transported onto the chuck table 81 of the chuck table mechanism 8 positioned in the workpiece loading / unloading area 24. The workpiece unloading means 17 is disposed between the workpiece loading / unloading area 24 and the cleaning means 14 and is placed on a chuck table 81 positioned in the workpiece loading / unloading area 24. The polished semiconductor wafer W is transferred to the cleaning means 14.

  The first cassette 11 containing the semiconductor wafer W as a workpiece is placed in a predetermined cassette carry-in area in the main portion 21 of the apparatus housing 2. Then, when all the semiconductor wafers W before being polished that were accommodated in the first cassette 11 placed in the cassette carry-in area are unloaded, a plurality of semiconductor wafers W are accommodated in place of the empty cassette 11. A new cassette 11 is manually placed in the cassette carry-in area. On the other hand, when a predetermined number of polished semiconductor wafers W are loaded into the second cassette 12 placed in a predetermined cassette unloading area in the main portion 21 of the apparatus housing 2, the second cassette 12 is manually moved. It is unloaded and a new empty second cassette 12 is placed.

Next, the polishing operation performed by the above-described polishing apparatus will be described mainly with reference to FIGS.
The semiconductor wafer W as a workpiece before polishing, which is accommodated in the first cassette 11, is transported by the vertical movement and advancing / retreating operation of the workpiece conveying means 15 and is placed on the workpiece temporary placing means 13. The The semiconductor wafer W mounted on the workpiece temporary mounting means 13 is positioned in the workpiece loading / unloading area 24 by the turning operation of the workpiece loading means 16 after being centered here. Is mounted on a chuck table 81 of the chuck table mechanism 8. A semiconductor wafer W as a workpiece placed on the chuck table 81 is sucked and held on the chuck table 81 by suction means (not shown).

  When the semiconductor wafer W is sucked and held on the chuck table 81, the chuck table moving means (not shown) is operated to move the chuck table 81 in the direction indicated by the arrow 23a and position it in the polishing area 25. When the chuck table 81 holding the semiconductor wafer W is positioned in the polishing zone, the polishing liquid supply means 9 is activated and the power supply means 6 is activated. Then, as shown in FIG. 6, the chuck table 81 holding the semiconductor wafer W is rotated in a direction indicated by an arrow 81a at, for example, 70 rpm, and the servo motor 323 is driven to move the polishing wheel 5 in a direction indicated by an arrow 5a, for example, 50 rpm. And the pulse motor 74 of the polishing feed means 7 is driven to rotate forward to lower or advance the polishing unit 3, and the polishing pad 52 of the polishing wheel 5 is moved to the back surface (upper surface) of the semiconductor wafer W on the chuck table 81. Is pressed with a predetermined load. When the polishing liquid supply means is operated in this way, as described above, the electrolyte is supplied with the electrolyte supply path 322a, the communication path 42 provided in the wheel mount 4, the electrolyte introduction path 512 provided in the wheel base 51, and the positive electrode. Through the communication holes 531 provided in the plate 53 and the communication holes 541 provided in the negative electrode plate 54, the plurality of communication grooves 521 provided in the polishing pad 52 are passed through the plurality of electrolyte outflow holes 522 to the chuck table 81. It flows out to the back surface (upper surface) of the held semiconductor wafer W. On the other hand, when the power supply means 6 is operated, as described above, the DC power supplies 61a, 61b, 61c, 61d to the slip rings 62a, 62b, 62c, 62d, the conductors not shown, the four positive electrode plugs 43, and the four positive electrodes. A voltage is applied between the four positive electrode plates 53 and the four negative electrode plates 54 via the terminal 55 and a conductive wire (not shown), and the positive electrode plate 53 and the negative electrode plate 54 are electrically connected via the electrolytic solution. Thus, the back surface (upper surface) of the semiconductor wafer W held on the chuck table 81 is electrolytically polished, and for example, the metal film laminated on the back surface of the semiconductor wafer W can be removed. Thus, since the semiconductor wafer W is electrolytically polished, the pressing force by the polishing wheel 5 can be reduced. For example, when the metal electrode is embedded in the semiconductor wafer W, the metal electrode is not depressed.

  When the polishing operation is completed as described above, the operations of the polishing liquid supply means 9 and the power supply means 6 are stopped, and the pulse motor 74 of the polishing feed means 7 is driven in reverse to raise the spindle unit 32 to a predetermined position. At the same time, the rotation of the polishing wheel 5 is stopped, and further, the rotation of the chuck table 81 is stopped. Then, the chuck table 81 is positioned in the workpiece loading / unloading area 24 (see FIG. 1). If the chuck table 81 is positioned in the workpiece loading / unloading area 24, the suction holding of the polished semiconductor wafer W on the chuck table 81 is released, and the semiconductor wafer W whose suction holding is released is processed. It is unloaded by the object unloading means 17 and conveyed to the cleaning means 14. The semiconductor wafer W transferred to the cleaning means 14 is cleaned here and then stored in a predetermined position of the second cassette 12 by the workpiece transfer means 15.

As described above, the polishing apparatus in the illustrated embodiment has the polishing wheel 5 mounted on the wheel mount 4 provided at the lower end of the rotary spindle 322, and is held on the chuck table 81 while supplying the electrolytic solution to the polishing wheel 5. Since the processed workpiece is electropolished, it is easy to carry the workpiece into and out of the chuck table 81. Therefore, the workpiece carrying-in means 16 and the workpiece carrying-out means 17 are compared with a construction in which the workpiece is held by the polishing head mounted on the rotary spindle side as in the conventional electrolytic polishing apparatus described above. A relatively simple configuration can be obtained.
In the polishing apparatus according to the embodiment, the DC power source of the power supply means 6 is divided into four, so that a small DC power source can be appropriately adjusted and replaced with a large power source.

2: Device housing 3: Polishing unit 31: Moving base 32: Spindle unit 321: Spindle housing 322: Rotating spindle 323: Servo motor 4: Wheel mount 43: Positive electrode plug 44: Negative electrode plug 5: Polishing wheel 51: Wheel Base 52: Polishing pad 53: Positive electrode plate 54: Negative electrode plate 55: Positive electrode terminal 56: Negative electrode terminal 6: Power supply means 7: Polishing unit feed mechanism 8: Chuck table mechanism 81: Chuck table 11: First Cassette 12: Second cassette 13: Temporary workpiece placing means 14: Cleaning means 15: Workpiece conveying means 16: Workpiece carrying means 17: Workpiece carrying means

Claims (2)

A chuck table configured to hold and rotate a workpiece, and a polishing means for polishing the workpiece held on the chuck table. The polishing means is provided on a rotating spindle and a lower end of the rotating spindle. In a polishing apparatus comprising a provided wheel mount and a polishing wheel detachably attached to the lower surface of the wheel mount,
The polishing wheel includes a wheel base having an upper surface mounted on the lower surface of the wheel mount, and a polishing pad mounted on the lower surface of the wheel base and having a plurality of electrolyte outflow holes. Includes a positive electrode plate having a plurality of communication holes communicating with a plurality of electrolyte outflow holes provided in the polishing pad and an electrolyte solution communicating with the plurality of communication holes. There is an introduction passage,
The wheel mount includes a communication path that connects an electrolyte introduction path provided in the wheel base and an electrolyte supply path provided in the rotary spindle;
Comprising power supply means for applying a voltage between the positive electrode plate and the negative electrode plate;
A polishing apparatus characterized by that.   The wheel base of the grinding wheel is provided with a positive electrode terminal and a negative electrode terminal that are respectively connected to the positive electrode plate and the negative electrode plate and project from the upper surface. The polishing apparatus according to claim 1, wherein a plus electrode plug and a minus electrode plug connected to the supply means and fitted to the plus electrode terminal and the minus electrode terminal, respectively, are disposed.

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