JPH11262862A - Double side polishing device and slurry supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To polish a work with high precision by uniformly delivering slurry throughout a lower surface plate during rotation of an upper surface plate and the lower surface plate. SOLUTION: A sun gear 1, a lower surface plate 2, and internal gear 3, an upper surface plate 4 and a slurry supply mechanism 5 for supply slurry to the lower surface plate 2 are provided. Specifically, a center hole 20 in the lower surface plate 2 is set to be smaller than a center hole 40 in the upper surface plate 4, to form a slurry receiving face 22 inside the polishing face 21 of the lower surface plate 2. The slurry supply mechanism 5 includes a slurry supply tube 50 mounted on the upper surface plate 4 and directed to the slurry receiving face 22, a plurality of slurry supply holes 51-54 made at almost equal spaces to the radial direction of the upper surface plate 4, and a slurry supply source 59 for supplying slurry via a tube 56 to the slurry supply tube 50 and the slurry supply holes 51-54.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-side polishing apparatus and a slurry supply method for polishing both surfaces of a work with an upper and lower platen rotating while supplying slurry, and more particularly, to a method of supplying slurry to a polishing surface of a lower platen. The present invention relates to a double-side polishing apparatus and a slurry supply method having a feature in a supply mechanism.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a conventional double-side polishing apparatus. As shown in FIG. 8, the double-side polishing apparatus comprises:
The carrier 110 meshed with the sun gear 101 and the internal gear 102 is revolved around itself by the driving rotation of the sun gear 101, and the lower platen 100 and the upper platen 120 are rotated in opposite directions to simultaneously grind both surfaces of the work W. Device. In addition, the work W
Polishing efficiency is improved and the upper and lower platens 10 are polished during polishing.
A slurry supply mechanism for supplying a slurry for cooling heat generated at 0 and 120 to the lower platen 100 is provided. This slurry supply mechanism supplies the slurry to the tube 20.
Slurry supply hole 20 drilled in upper platen 120 through 1
2 and flows out from the lower end opening of the slurry supply hole 202 to the lower platen 100 side. The positions of the plurality of slurry supply holes 202 are determined by the lower platen 100 and the upper platen 120.
When the slurry is still, the slurry is supplied to the slurry supply hole 20.
When the slurry flows out from the lower end opening of the lower surface plate 1
It is set so as to evenly spread over the polished surface of No. 00. For example, as shown in FIG. 9, four slurry supply holes 202 are formed at equal intervals in the radial direction of the upper platen 120, and these four slurry supply holes 202 are formed in the circumferential direction of the upper platen 120. Drilled at intervals.

[0003]

However, the above-mentioned conventional double-side polishing apparatus has the following problems. Lower surface plate 1
00 and the upper platen 120 are stationary, so that a plurality of slurries are distributed evenly to the lower platen 100.
Since the drilling position of the supply hole 202 is set, the lower platen 1
00 and the lower platen 10 of the slurry when the upper platen 120 rotates.
The outflow distribution toward zero is biased. That is, as shown in FIG. 10, the slurry S flowing out from each slurry supply hole 202 onto the polishing surface of the lower platen 100 is moved radially outward of the lower platen 100 by the centrifugal force of the lower platen 100. For this reason, the slurry S flowing out from the slurry supply hole 202 is used for the inner portion 100 a on the polishing surface of the lower platen 100.
Do not go to. As a result, the heat of the inner peripheral portion 100a rises more than the other portions, which adversely affects the polishing accuracy of the work W.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the slurry can be evenly distributed over the entire lower platen when the upper platen and the lower platen are rotating, so that the polishing accuracy of the workpiece can be improved. It is an object of the present invention to provide a double-side polishing apparatus and a slurry supply method.

[0005]

According to a first aspect of the present invention, there is provided a donut having a sun gear and a polishing surface disposed concentrically outside the sun gear and for polishing a lower surface of a work. Polishing the upper surface of a workpiece held in a carrier that is arranged concentrically outside the lower surface plate, the lower surface plate, and concentrically with the lower surface plate and that is engaged with the sun gear and the internal gear An upper surface plate having a polishing surface for polishing, and a double-side polishing apparatus having a slurry supply mechanism for supplying slurry toward the lower surface plate, wherein the center hole of the lower surface plate is set smaller than the center hole of the upper surface plate. Forming a slurry receiving surface inside the polishing surface of the lower surface plate, a slurry supply mechanism, a slurry supply pipe disposed in the center hole of the upper surface plate and having a lower end opening facing the slurry receiving surface of the lower surface plate; A plurality of slurry supply holes which penetrate the platen in the vertical direction and are arranged at substantially equal intervals in the radial direction of the upper platen together with the slurry supply pipe, and supply the slurry to the plurality of slurry supply holes and the slurry supply pipe. And a slurry source. With this configuration, while rotating the upper platen and the lower platen in directions opposite to each other, and rotating at least one of the sun gear and the internal gear, the carrier rotates around the sun gear, and both surfaces of the work held by the carrier are rotated. The polishing is performed at the same time by the polishing surfaces of the upper surface plate and the lower surface plate. Then, when the slurry is supplied from the slurry supply source of the slurry supply mechanism to the plurality of slurry supply holes and the slurry supply pipe, the slurry moves from the slurry receiving surface to the polishing surface side by the centrifugal force of the lower platen, and the slurry is transferred to the lower platen. Spread evenly across the polished surface. Also, by setting the rotation direction of at least one of the sun gear and the internal gear so that the rotation direction of the carrier is opposite to the revolving direction,
The slurry on the polishing surface is taken into the lower side of the carrier.

According to a second aspect of the present invention, there is provided a donut-shaped lower surface plate having a sun gear, a concentric outer surface of the sun gear, and a polishing surface for polishing the lower surface of the work, and a concentric outer surface of the lower surface plate. Internal gear disposed on the upper surface plate having a polishing surface for polishing the upper surface of the work held on the carrier meshed with the sun gear and the internal gear disposed opposite the lower surface plate, In a double-side polishing apparatus having a slurry supply mechanism for supplying slurry toward the lower platen, the slurry supply mechanism is disposed at substantially equal intervals in the radial direction of the upper platen, penetrating the upper platen vertically. A plurality of slurry supply holes, and a slurry supply source for supplying a slurry having a flow rate substantially inversely proportional to the distance between each slurry supply hole and the center of the upper platen to each slurry supply hole. With this configuration, the slurry flows out from the plurality of slurry supply holes arranged in the radial direction of the upper platen to the lower platen. Then, the slurry which has flowed out to the lower platen by the action of the centrifugal force based on the rotation of the lower platen moves radially outward of the lower platen. At this time, since a slurry having a flow rate substantially in inverse proportion to the distance between each slurry supply hole and the center of the upper platen continues to flow to the lower platen, a large amount of slurry flows from the inner peripheral portion to the outer peripheral portion of the polishing surface of the lower platen. Then, the slurry is evenly distributed on the polishing surface.

By the way, it is considered that a method of uniformly distributing the slurry in the radial direction of the lower platen is established as the invention. In view of the above, the invention according to claim 3 is characterized in that the upper surface plate and the lower surface plate are rotated in opposite directions with the polishing surfaces facing each other, and the sun gear arranged concentrically inside the lower surface plate and concentrically outside the lower surface plate. By rotating at least one of the internal gears arranged on the upper surface plate, the workpiece is held and the carrier engaged with the sun gear and the internal gear revolves around the sun gear and rotates in a direction opposite to the revolving direction. The slurry flows out from the plurality of slurry supply holes drilled at substantially equal intervals in the radial direction to the polishing surface of the lower platen, and is positioned in the same row as the plurality of slurry supply holes into the center hole of the upper platen. The central hole of the lower platen was set smaller than the central hole of the upper platen, and the slurry was allowed to flow out from the arranged slurry supply pipe to the slurry receiving surface formed inside the polishing surface. In addition, the uptake of the slurry into the lower side of the carrier is as follows:
It is understood that the larger the difference between the revolving speed of the carrier and the revolving speed of the lower stool, the more efficient the operation. Therefore, a fourth aspect of the present invention provides the slurry supply method according to the third aspect,
The lower platen is rotated in the direction opposite to the direction of rotation of the carrier.

According to a fifth aspect of the present invention, the upper surface plate and the lower surface plate are rotated in opposite directions with the polishing surfaces facing each other, and the sun gear and the outer surface of the lower surface plate concentrically arranged inside the lower surface plate. By rotating at least one of the internal gears arranged concentrically, holding the work and revolving the carrier meshed with the sun gear and the internal gear around the sun gear and rotating in the opposite direction to the revolving direction, From a plurality of slurry supply holes drilled at substantially equal intervals in the radial direction of the upper platen, a slurry having a flow rate substantially in inverse proportion to the distance between each of the slurry supply holes and the center of the upper platen flows out to the polishing surface of the lower platen. Configuration. Further, according to a sixth aspect of the present invention, in the slurry supply method according to the fifth aspect, the lower platen is rotated in a direction opposite to the revolving direction of the carrier.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a partial sectional view showing a double-side polishing apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the double-side polishing apparatus includes a sun gear 1 and a lower platen 2.
, Internal gear 3, upper platen 4, and slurry supply mechanism 5
Is provided.

The sun gear 1 is fixed to the upper end of the rotating shaft 10. A driver 11 having a vertical groove 11a is mounted on the sun gear 1, and the rotating shaft 10 is rotated by a motor (not shown). Sun gear 1 and driver 11
And rotate together.

The lower platen 2 is a donut-shaped plate fixedly mounted on a pedestal 29 which is concentrically disposed outside the sun gear 1 and rotated by a motor (not shown). The diameter of the center hole 20 of the lower platen 2 is set smaller than the center hole 40 of the upper platen 4 to be described later, and a slurry receiving surface 22 is provided inside a polishing surface 21 having substantially the same width as the upper platen 4. Are formed.

The internal gear 3 is disposed concentrically outside the lower platen 2 and is rotated by a motor (not shown).

On the other hand, the upper surface plate 4 is disposed such that its polishing surface 41 faces the polishing surface 21 of the lower surface plate 2, and is attached to the lower side of the suspension plate 42. The suspension plate 42 is a cylinder 4
The third piston rod 43a is rotatably connected to the distal end of the third piston rod 43a via a bearing 44. As a result, the upper platen 4 is lowered by the cylinder 43, the vertical groove 11a of the driver 11 is engaged with the hook 45 fixed to the upper platen 4, and the rotating shaft 10 is rotated. Is Sun Gear 1
And rotate in the same direction.

The slurry supply mechanism 5 is a mechanism for supplying the slurry to the lower platen 2 side. The slurry supply pipe 50 and the four slurry supply holes 51 to 54 are provided in a line in the radial direction of the upper platen 4. , A slurry supply source 59. The slurry supply pipe 50 is disposed in the center hole 40 of the upper stool 4, and is fixed to the upper stool 4 such that the lower end opening 50 a is located directly above the slurry receiving surface 22 of the lower stool 2. It is attached to the metal fitting 55. Slurry supply hole 5
1 to 54 penetrate the upper platen 4 in the up-down direction, and the intervals between the slurry supply holes 51 to 54 are set substantially equal. As shown in FIG. 2, eight sets of the above-mentioned row of slurry supply pipes 50 and slurry supply holes 51 to 54 are provided at intervals of 45 ° in the circumferential direction of the upper platen 4, and the slurry is supplied to the lower platen 2. It is designed to flow evenly over the entire surface. In FIG. 1, a slurry supply source 59 is a device that supplies slurry to the slurry supply pipe 50 and the slurry supply holes 51 to 54, and the slurry is supplied through a flow path extending to the slurry supply pipe 50 and the slurry supply holes 51 to 54. Send out. Specifically, tubes 56 are attached to each of the slurry supply pipe 50 and the slurry supply holes 51 to 54, and the upper end opening of each tube 56 has the lower surface opening of a ring-shaped gutter 57 attached to the outer peripheral surface of the suspension plate 42. It is connected to. Then, a flow pipe 58 extends from the slurry supply source 59 to a position above the gutter 57.
a is attached. Thus, the slurry is sent from the slurry supply source 59 to the distribution pipe 58, and the cock 58a is opened, whereby the slurry is supplied to the gutter 57. Then, the slurry reaches the slurry supply pipe 50 and the slurry supply holes 51 to 54 through the tube 56, and flows out from the lower end openings of the slurry supply pipe 50 and the slurry supply holes 51 to 54 toward the lower platen 2.

Next, the operation of the double-side polishing apparatus according to this embodiment will be described. This operation specifically executes the slurry supply method according to the third and fourth aspects of the present invention. FIG. 3 is a partial cross-sectional view of a double-side polishing apparatus for illustrating a polishing operation. As shown in FIG. 3, after the carrier 6 containing the work W in the holding hole 60 is engaged with the sun gear 1 and the internal gear 3, the upper platen 4 is lowered by the cylinder 43, and the hook is inserted into the vertical groove 11 a of the driver 11. By rotating the sun gear 1 and the lower stool 2 in opposite directions in a state where the gears 45 are engaged, the carrier 6
, And both surfaces of the work W are simultaneously polished by the lower stool 2 and the upper stool 4 rotating in opposite directions. At this time, the rotation speed ratio between the sun gear 1 and the internal gear 3 is adjusted so that the rotation direction B and the revolving direction C of the carrier 6 are reversed, as shown in FIG. The direction C and the rotation direction D of the lower stool 2 are reversed.

In parallel with the above operation, the slurry supply source 59 of the slurry supply mechanism 5 shown in FIG.
Supply pipe 50 and slurry supply hole 5 provided in
The work W is polished by flowing the slurry from 1 to 54 toward the lower platen 2. At this time, since the revolving direction C of the carrier 6 is opposite to the rotation direction B of the carrier 6 and the rotation direction D of the lower stool 2, as shown in FIG. 4, the carrier 6 flows out of the slurry supply pipe 50 and the slurry supply holes 51 to 54. The slurry is taken in between the lower surface of the work W and the polishing surface 21, and the work W is efficiently polished by the slurry. By the way, the lower surface plate 2 which contributes to the polishing of the work W
Is a polished surface 21 with which all the works W come into contact.
Therefore, if the heat generated during polishing is deviated in the radial direction of the polishing surface 21, the polishing accuracy of the work W will be degraded. In the conventional double-side polishing apparatus shown in FIG. 8, since the slurry is supplied only to the polishing surface 21, the slurry inside the polishing surface 21 moves outward by the centrifugal force of the lower platen 2, and the polishing surface 21 is removed. The heat in the inner part of the was high. However, in the double-side polishing apparatus of this embodiment, since the slurry flows out from the slurry supply holes 51 to 54 to the polishing surface 21 and also flows out from the slurry supply pipe 50, the heat of the polishing surface 21 is reduced in the radial direction. It becomes almost equal.
That is, as shown in FIG. 5, since the lower end opening 50a of the slurry supply pipe 50 is located directly above the slurry receiving surface 22 of the lower platen 2, the slurry from the slurry supply pipe 50 It will continue to leak. Therefore, the slurry S flowing out from the slurry supply holes 51 to 54 onto the polishing surface 21 of the lower surface plate 2 moves outward of the lower surface plate 2 due to the centrifugal force of the lower surface plate 2, and the inner portion 21 a of the polishing surface 21 The outer part will continue to cool. Then, the slurry receiving surface 2
The slurry S that has flowed out onto the lower platen 2 moves to the outside of the lower platen 2 while cooling the inner portion 21 a by the centrifugal force of the lower platen 2. As a result, the entire polishing surface 21 of the lower stool 2 is continuously cooled by the slurry S from the slurry supply pipe 50 and the slurry supply holes 51 to 54, and the temperature of the entire polishing surface 21 becomes substantially uniform.

As described above, according to the double-side polishing apparatus of this embodiment, the entire polishing surface 21 contributing to the polishing of the work W is constantly cooled by the slurry supply pipe 50 and the slurry S flowing out from the slurry supply holes 51 to 54. Since the temperature distribution of the polishing surface 21 is not biased, the work W
Can be polished with high precision.

(Second Embodiment) FIG. 6 is a partial sectional view showing a double-side polishing apparatus according to a second embodiment of the present invention. The same members as those shown in FIGS. 1 to 5 are denoted by the same reference numerals and described. In this embodiment, the slurry supply pipes 50 of the slurry supply mechanism 5 and the slurry receiving surface 22 of the lower platen 2 are not specially provided.
The fourth embodiment differs from the first embodiment in that the structure is such that the temperature of the polishing surface 21 of the lower stool 2 is made uniform by changing the flow rate of the slurry flowing out of the lower surface 4 per unit time.

Specifically, the center hole 20 of the lower platen 2 is set to the same size as the center hole 40 of the upper platen 4. In the slurry supply mechanism 5 ', the gutter 57
The four tubes 56 respectively connected to the slurry supply holes 51 to 54 are connected to a connection pipe 57 a attached to the lower side of
Are connected. The four tubes 56 are provided with flow control valves 56a to 56d, respectively.
The flow rate adjustment valves 56a to 56d
The flow rate of the slurry flowing out of the base plate 54 is adjusted so as to be substantially inversely proportional to the distance from the center of the upper stool 4. In other words, the slurry on the lower platen 2 receives a centrifugal force proportional to the distance from the center of the lower platen 2.

Next, the operation of the double-side polishing apparatus according to this embodiment will be described. This operation specifically executes the slurry supply method according to the fifth and sixth aspects of the present invention. FIG. 7 is a partial cross-sectional view showing a state in which the slurry flows on the polishing surface 21 of the lower stool 2. As shown in FIG. 7, the largest amount of the slurry S flows out from the slurry supply hole 51 to the region 21 b immediately below the slurry supply hole 51. The centrifugal force at the position where the slurry S flows out is the smallest. For this reason, a part of the slurry S flowing out from the slurry supply hole 51 is directed toward the center hole 20 of the lower platen 2 and falls from the center hole 20 or is pulled back by a weak centrifugal force. Therefore, the region 21 b is cooled by the slurry S having a large flow rate flowing out from the slurry supply hole 51. Further, when the slurry 21 flows out from the slurry supply hole 52 to the region 21c, the region 21c is cooled by the slurry S flowing out from the slurry supply hole 52 and the slurry S flowing from the region 21b side. When the region 21d flows out of the hole 53 into the region 21d, the region 21d is cooled by the slurry S having a flow rate flowing out of the slurry supply hole 53 and the slurry S flowing from the regions 21c and 21b. When the liquid is discharged from the area 54 to the area 21e, the area 21
e is cooled by the slurry S having a flow rate flowing out from the slurry supply hole 54 and the slurry S flowing from the regions 21d, 21c, and 21b. As a result, the flow rates of the slurry S flowing on the regions 21b to 21e become substantially equal, and the temperatures of the regions 21b to 21e become substantially equal.

As described above, according to the name of this embodiment, the slurry having substantially the same flow rate can be made to flow in the radial direction of the lower stool 2, so that the temperature uniformity of the lower stool 2 can be further improved. it can. The other configuration, operation, and effect are the same as those of the first embodiment, and the description thereof is omitted.

The present invention is not limited to the above embodiment, and various modifications and changes can be made within the scope of the invention. For example, in the above embodiment,
Although four slurry supply holes 51 to 54 are formed in the upper stool 4, this does not mean that two, three, or five or more slurry supply holes are formed.
In the above embodiment, the revolving direction C of the carrier 6 and the rotation direction D of the lower stool 2 are reversed. However, even in the same direction, a difference in speed between the carrier 6 and the lower stool 2 may be generated. .

[0023]

【The invention's effect】

As described above in detail, according to the present invention, the slurry spreads evenly in the radial direction of the polished surface of the lower stool, so that the temperature in the radial direction of the surface becomes substantially uniform. There is an excellent effect that highly accurate polishing of the work becomes possible. In addition, by setting the rotation direction of the lower platen to the direction opposite to the revolving direction of the carrier, the slurry can be reliably taken into the lower side of the carrier, and the workpiece can be reliably polished through the slurry. it can.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a double-side polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of the upper surface plate shown in FIG. 1 as viewed from below.

FIG. 3 is a partial cross-sectional view of a double-side polishing apparatus for illustrating a polishing operation.

FIG. 4 is a schematic plan view showing the direction of rotation of the carrier and the direction of rotation of a lower platen.

FIG. 5 is a partial cross-sectional view showing a state in which the slurry flows on the lower platen shown in FIG.

FIG. 6 is a partial cross-sectional view showing a double-side polishing apparatus according to a second embodiment of the present invention.

FIG. 7 is a partial cross-sectional view showing a state in which the slurry flows on the lower platen shown in FIG.

FIG. 8 is a sectional view showing a double-side polishing apparatus according to a conventional example.

FIG. 9 is a plan view of the upper surface plate shown in FIG. 8 as viewed from below.

FIG. 10 is a partial cross-sectional view showing a state in which the slurry flows on the lower platen shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sun gear, 2 ... Lower surface plate, 3 ... Internal gear, 4 ... Upper surface plate, 5 ... Slurry supply mechanism, 6 ... Carrier, 50 ... Slurry supply pipe, 51-54 ... Slurry supply hole, 59 ... Slurry supply source, S: slurry, W: work.

Claims (6)

[Claims] 1. A sun gear, a donut-shaped lower platen concentrically disposed outside the sun gear and having a polishing surface for polishing a lower surface of a work, and concentrically disposed outside the lower platen. An internal gear, an upper surface plate having a polishing surface arranged to face the lower surface plate, and having a polishing surface for polishing an upper surface of the work held by a carrier meshed with the sun gear and the internal gear; A double-side polishing apparatus having a slurry supply mechanism for supplying slurry toward the platen, wherein a center hole of the lower platen is set smaller than a center hole of the upper platen, and a slurry is provided inside a polishing surface of the lower platen. Forming a receiving surface, the slurry supply mechanism being disposed in a center hole of the upper platen and having a lower end opening directed to the slurry receiving surface of the lower platen; A plurality of slurry supply holes which penetrate vertically and are disposed at substantially equal intervals in the radial direction of the upper platen together with the slurry supply pipe, and a slurry supply for supplying the slurry to the plurality of slurry supply holes and the slurry supply pipe; A double-side polishing apparatus characterized by comprising: a source. 2. A sun gear, a donut-shaped lower platen concentrically disposed outside the sun gear and having a polishing surface for polishing a lower surface of a work, and concentrically disposed outside the lower platen. An internal gear, an upper surface plate having a polishing surface arranged to face the lower surface plate, and having a polishing surface for polishing an upper surface of the work held by a carrier meshed with the sun gear and the internal gear; A double-side polishing apparatus comprising: a slurry supply mechanism for supplying slurry toward the plate; wherein the slurry supply mechanism is disposed at substantially equal intervals in a radial direction of the upper plate through the upper plate vertically. A plurality of slurry supply holes, and a slurry supply source for supplying slurry to each slurry supply hole at a flow rate substantially inversely proportional to the distance between each of the slurry supply holes and the center of the upper platen. And a double-side polishing apparatus. 3. An upper platen and a lower platen are rotated in opposite directions with the polishing surfaces facing each other, and a sun gear disposed concentrically inside the lower platen and concentrically disposed outside the lower platen. By rotating at least one of the internal gears, the work is held, and the carrier engaged with the sun gear and the internal gear revolves around the sun gear and rotates in a direction opposite to the revolving direction. The slurry flows out from the plurality of slurry supply holes drilled at substantially equal intervals in the radial direction to the polishing surface of the lower platen, and the upper platen is positioned in the same row as the plurality of slurry supply holes. From the slurry supply pipe disposed in the center hole, the center hole of the lower platen is set smaller than the center hole of the upper platen, and the slurry flows out to the slurry receiving surface formed inside the polishing surface. And a slurry supply method. 4. The slurry supply method according to claim 3, wherein the lower platen is rotated in a direction opposite to a revolving direction of the carrier. 5. A sun gear disposed concentrically inside the lower platen and concentrically outside the lower platen by rotating the upper platen and the lower platen in opposite directions with the polishing surfaces facing each other. By rotating at least one of the internal gears, the work is held, and the carrier engaged with the sun gear and the internal gear revolves around the sun gear and rotates in a direction opposite to the revolving direction. From a plurality of slurry supply holes drilled at substantially equal intervals in the radial direction, a slurry having a flow rate substantially inversely proportional to the distance between each of the slurry supply holes and the center of the upper platen flows out to the polishing surface of the lower platen, A slurry supply method characterized by the above-mentioned. 6. The slurry supply method according to claim 5, wherein the lower platen is rotated in a direction opposite to a revolving direction of the carrier.