JP2002113653A - Substrate retaining device and polishing device with the substrate retaining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate retaining device and a polishing device with the substrate retaining device capable of achieving the evenness of polishing and safety by eliminating the relative motion of a retainer ring and the main body of a top ring, achieving the safety in the motion of the retainer ring in polishing, and keeping the distance between the retainer ring and the edge part of an object for polishing constant. SOLUTION: The substrate retaining device for retaining an object for polishing, a semiconductor wafer W, and pressing the wafer against the polishing surface on a polishing table 30 comprises the main body 2 of the top ring for retaining the semiconductor wafer W, the retainer ring 3 fixed to or integrally formed with the main body 2 of the top ring for retaining the outer rim of the semiconductor wafer W, and a fluid chamber 8 formed inside the main body 2 of the top ring and covered with an elastic film 4, to which a fluid is fed. The semiconductor wafer W is pressed against the polishing surface through the elastic film 4 by feeding the pressurized fluid into the fluid chamber 8, and the retainer ring 3 is pressed against the polishing surface by applying the pressing force to the main body 2 of the top ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate holding apparatus for holding a substrate such as a semiconductor wafer when polishing and flattening the substrate, and a polishing apparatus having the substrate holding apparatus.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become more miniaturized and the element structure has become more complex, and the number of layers of logic-related multilayer wiring has increased, the surface of the semiconductor device has become more and more uneven and the level difference has increased. There is a tendency. This is because, in the manufacture of semiconductor devices, a process of forming a thin film, performing fine processing for patterning and opening, and then stacking the next thin film is repeated many times. If the surface irregularities increase, the film thickness at the stepped part becomes thinner when forming the thin film, and the open due to the disconnection of the wiring and the short circuit due to the insulation failure between the wiring layers occur, so that a good product cannot be obtained or the yield decreases. I do. In addition, even if it operates normally at the initial stage, there is a problem of reliability when used for a long time.

Another major problem of surface irregularities is the lithography process. This is because, if there is unevenness on the irradiation surface during exposure, the lens of the exposure system is partially out of focus and the formation of a fine pattern itself becomes difficult. For these reasons, surface flattening techniques have become increasingly important in semiconductor device manufacturing processes. The most important of these planarization techniques is chemical mechanical polishing (CMP). In this chemical mechanical polishing, a semiconductor wafer is brought into sliding contact with a polishing surface while supplying a polishing liquid containing abrasive grains such as silica (SiO ₂ ) onto a polishing surface such as a polishing pad using a polishing apparatus. Polishing.

Conventionally, this type of polishing apparatus includes a polishing table having a polishing surface composed of a polishing pad and a substrate holding device called a top ring or a carrier head for holding a semiconductor wafer. . The substrate holding device presses the semiconductor wafer against the polishing table at a predetermined pressure while holding the semiconductor wafer, and makes the semiconductor wafer slide against the polishing surface by relatively moving the substrate holding device and the polishing table. The surface of the semiconductor wafer is polished flat and mirror-finished.

In the above-mentioned polishing apparatus, if the relative pressing force between the semiconductor wafer being polished and the polishing surface of the polishing pad is not uniform over the entire surface of the semiconductor wafer,
Under-polishing or over-polishing occurs depending on the pressing force of each part. Therefore, the semiconductor wafer holding surface of the substrate holding device is formed of an elastic film made of an elastic material such as rubber, and a fluid pressure such as air pressure is applied to the back surface of the elastic film, so that the pressing force applied to the semiconductor wafer is uniform over the entire surface. Is also being done. In this case, the periphery of the semiconductor wafer is a contact / non-contact boundary with the polishing surface. In particular, since the polishing pad has elasticity, the polishing pressure applied to the peripheral portion of the semiconductor wafer becomes non-uniform, and only the peripheral portion of the semiconductor wafer is polished to a large extent, resulting in a so-called "edge dripping". A substrate holding device having a structure in which a polishing surface located on the outer peripheral side of a semiconductor wafer is pressed by a guide ring or a retainer ring for holding the outer peripheral edge of the semiconductor wafer to prevent the edge dripping of the semiconductor wafer is also used. I have. In this apparatus, the retainer ring is pressed against the polishing surface by a fluid pressure such as an air pressure.

FIG. 10 is a schematic view of a substrate holding apparatus having a structure in which the above-described semiconductor wafer is pressed against the polishing surface by a fluid pressure such as air pressure and the retainer ring is pressed against the polishing surface by a fluid pressure. As shown in FIG. 10, a top ring 50 constituting a substrate holding device includes a top ring main body 51 having an accommodation space therein, and a semiconductor wafer W accommodated in the top ring main body 51 and having a semiconductor wafer W placed on a polishing table 60. A wafer pressing mechanism 52 that presses against the polishing surface 61;
3 and a retainer ring pressing mechanism 54 that presses the retainer ring 53 against the polishing surface 61.

Although the detailed structure of the wafer pressing mechanism 52 is not shown, the wafer pressing mechanism 52 is formed of an elastic film made of an elastic material such as rubber connected to the top ring main body 51. Is supplied, and the semiconductor wafer W is pressed against the polishing surface 61 by the fluid pressure. Although the detailed structure is not shown, the retainer ring pressing mechanism 54 is formed of an elastic film made of an elastic material such as rubber and connected to the top ring main body 51. A pressurized fluid is supplied, and the retainer ring 53 is pressed against the polishing surface 61 by the fluid pressure. The top ring main body 51 is connected to a drive shaft 55, and the drive shaft 55 is raised and lowered by a lifting mechanism such as an air cylinder.

In the above-described configuration, a state in which the semiconductor wafer W is brought close to the polishing surface 61 by operating the elevating mechanism such as an air cylinder connected to the drive shaft 55 to bring the entire top ring body 51 close to the polishing table 60. Then, a pressurized fluid at a predetermined pressure is supplied to the wafer pressurizing mechanism 52 to press the semiconductor wafer W against the polishing surface 61 of the polishing table 60. In this case, the polishing pressure applied to the semiconductor wafer W is adjusted to a desired value by adjusting the pressure of the pressurized fluid supplied to the wafer pressing mechanism 52. Further, a pressurized fluid of a predetermined pressure is supplied to the retainer ring pressurizing mechanism 54 to press the retainer ring 53 against the polishing surface 61 of the polishing table 60.

As described above, since the semiconductor wafer W is pressed against the polishing surface 61 by the fluid pressure, a uniform polishing pressure can be applied over the entire surface of the semiconductor wafer W from the center to the peripheral edge. Therefore, the entire surface of the semiconductor wafer W can be uniformly polished. Then, since the same pressing force as the polishing pressure applied to the semiconductor wafer W is applied to the retainer ring 53 via the retainer ring pressing mechanism 54, the polishing surface such as a polishing pad around the semiconductor wafer W , And the pressure distribution from the central portion of the semiconductor wafer W to the peripheral portion, and further to the outer peripheral portion of the retainer ring 53 outside the semiconductor wafer W becomes continuous and uniform. Therefore, it is possible to prevent the polishing amount at the peripheral portion of the semiconductor wafer W to be polished from being excessive or insufficient.

[0010]

In a conventional substrate holding apparatus using a fluid pressure for both the pressing of the semiconductor wafer and the pressing of the retainer ring as described above, the retainer ring is vertically moved (vertically) with respect to the top ring body. direction)
And it is constituted so that it can move freely to the left and right (radial direction). In other words, the retainer ring has a structure capable of independent movement with respect to the top ring main body. Therefore, the movement of the retainer ring, which affects the polishing uniformity of the outer peripheral portion of the semiconductor wafer, causes the required vertical movement with respect to the wafer. There is also a phenomenon that moves not only to the left and right. as a result,
The distance between the retainer ring and the peripheral portion (edge portion) of the semiconductor wafer is not constant, and there has been a problem in polishing uniformity and stability of the peripheral portion of the semiconductor wafer.

A further problem in chemical mechanical polishing (CMP) using such an abrasive fluid (slurry) is as follows.
When polishing a device wafer having a concavo-convex pattern, convex portions are preferentially polished in the initial stage of polishing, but concave portions are also gradually removed, so that the unevenness is not easily eliminated. In addition, there is a difference in the shaving method depending on the density of the uneven pattern on the wafer. This is because polishing is performed using a polishing pad with relatively soft elasticity and with a slurry-like polishing liquid containing a large amount of free abrasive grains. This is because it also acts on the recess.

For this reason, recently, cerium oxide (Ce)
Studies have been made on polishing a semiconductor wafer using a polishing surface made of so-called fixed abrasive grains in which abrasive grains such as O ₂ ) are fixed using a binder such as phenol resin. In the polishing using such fixed abrasive grains, the polishing surface is hard unlike the polishing pad in the case of conventional chemical mechanical polishing, so that the convex portions of the irregularities are preferentially polished, and the concave portions are hard to be polished. For,
There is an advantage that absolute flatness is easily obtained. However, a top ring suitable for a hard polished surface made of such fixed abrasive grains has not been developed.

The present invention has been made in view of the above circumstances, and eliminates the relative movement between the retainer ring and the top ring main body to obtain the stability of the behavior of the retainer ring during polishing and to obtain the retainer ring and the peripheral edge of the object to be polished. It is an object of the present invention to provide a substrate holding device capable of obtaining uniformity and stability of polishing while keeping a distance to a portion (edge portion) constant, and a polishing device provided with the substrate holding device.

[0014]

In order to achieve the above object, one aspect of the substrate holding apparatus of the present invention is a substrate holding apparatus for holding a substrate to be polished and pressing the substrate against a polishing surface on a polishing table. A top ring body that holds the substrate, a retainer ring that is fixed to or integrated with the top ring body and holds the outer peripheral edge of the substrate, and that is provided in the top ring body and covered with an elastic film. A fluid chamber to which a fluid is supplied, by pressing the substrate against the polishing surface via the elastic film by supplying a pressurized fluid into the fluid chamber, by applying a pressing force to the top ring body. The retainer ring is pressed against the polishing surface. Another aspect of the substrate holding device of the present invention is a substrate holding device for holding a substrate to be polished and pressing the substrate against a polishing surface on a polishing table, wherein the top ring main body holds the substrate, and the top ring main body. And a fluid chamber provided in the top ring main body and supplied with a fluid, and a pressurized fluid is supplied into the fluid chamber. In this case, the substrate is pressed against the polishing surface by fluid pressure, and the retainer ring is pressed against the polishing surface by applying a pressing force to the top ring main body.

According to the present invention, the retainer ring is provided integrally with the rigid top ring main body, and the retainer ring is moved up and down by the vertical movement of the top ring main body.
Thus, the pressing force on the top ring main body is used as the pressing force on the retainer ring, and unnecessary left and right (radial) movements of the retainer ring can be eliminated by the integral structure with the top ring main body. Therefore, it is possible to always minimize the distance between the retainer ring and the peripheral portion (edge portion) of the substrate to be polished, and to improve the uniformity of polishing and the stability of polishing at the outer peripheral portion of the substrate. be able to.

Further, since the retainer ring is formed integrally with the top ring main body, a highly rigid retainer ring structure is enabled, and the stability of the behavior of the retainer ring during polishing can be obtained. Then, inside the stable and high-rigidity retainer ring structure, the floating structure of the substrate holding and pressing mechanism follows the undulations of the polished surface, and as a result, the behavior of the retainer ring on the hard polished surface is stabilized, and Is obtained.

According to another aspect of the present invention, there is provided a polishing apparatus comprising: a polishing table having a polishing surface; and a top ring for holding a substrate to be polished and pressing the substrate against the polishing surface on the polishing table. Is formed with a hard polished surface, a pressurized chamber formed of an elastic film is provided in the top ring, and a pressurized fluid is supplied into the fluid chamber, whereby the substrate is polished through the elastic film. Is pressed. Another aspect of the polishing apparatus of the present invention includes a polishing table having a polishing surface, and a top ring that holds a substrate to be polished and presses the polishing surface on the polishing table, and hardens the polishing surface. And a fluid chamber is provided in the top ring, and the substrate is pressed against the polishing surface by fluid pressure by supplying a pressurized fluid into the fluid chamber. It is.

The top ring of the present invention constitutes a hard polished surface, and particularly has a compression modulus of 19.6 MPa (200 kPa).
g / cm ² ) or more.
According to the top ring of the present invention, since the substrate is held by the fluid pressure via the elastic film inside the highly rigid retainer ring, the unevenness of the hard polished surface is absorbed by the fluid pressure applied to the back surface of the substrate. it can. Therefore, even when a hard polishing surface is used, the polishing performance is good, and the vacuum suction holes of the backing pad are not transferred to the substrate. In addition,
The elastic film may be omitted, and the substrate may be directly pressed by the fluid.

One embodiment of the polishing apparatus of the present invention includes a polishing table having a polishing surface, a top ring for holding the substrate and pressing the polishing table, and a retainer ring for pressing the polishing surface around the substrate. A groove extending from the outside to the inside is provided on the lower surface of the retainer ring, and the groove is not formed up to the inner peripheral portion of the retainer ring, and a wall is left. According to the present invention, by providing a plurality of grooves on the contact surface side of the retainer ring with the polishing surface, the polishing liquid can easily enter the inside of the retainer ring, and the supply of the polishing liquid to the semiconductor wafer can be ensured. Deterioration of polishing uniformity and reduction of polishing rate caused by insufficient liquid can be prevented. In addition, the grooves are provided to be inclined with respect to the radial direction in accordance with the rotation direction of the retainer ring, so that the polishing liquid can be more easily entered. And, by forming a groove leaving a wall without forming a groove up to the inner peripheral portion of the retainer ring, controlling the entry of the polishing liquid, while ensuring the supply of the polishing liquid to the semiconductor wafer inside the retainer ring, Local overpolishing of the semiconductor wafer can be suppressed.

Further, the polishing method of the present invention has a polishing table having a polishing surface and a top ring, and holds the substrate to be polished by the top ring and presses the substrate against the polishing surface on the polishing table. In the polishing method for polishing, by supplying a pressurized fluid to a fluid chamber provided in the top ring, the substrate is pressed against a polishing surface formed of a hard polishing member by fluid pressure and polished. It is a feature.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a substrate holding apparatus according to the present invention and a polishing apparatus provided with the substrate holding apparatus will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view showing a first embodiment of the substrate holding device of the present invention, and FIG. 2 is a longitudinal sectional view showing an operation state of the substrate holding device shown in FIG. The substrate holding device is a device that holds a substrate such as a semiconductor wafer to be polished and presses the substrate against a polishing surface on a polishing table. As shown in FIG. 1, a top ring 1 constituting a substrate holding device includes a cylindrical container-shaped top ring main body 2 having an accommodation space therein, and a retainer ring 3 fixed to a lower end of the top ring main body 2. ing. The top ring main body 2 is made of a material having high strength and rigidity such as metal and ceramics, and the top ring main body 2 is composed of a disc-shaped upper plate 2A and a peripheral wall portion 2B extending below the upper plate 2A. I have. The retainer ring 3 is fixed to a lower end of the peripheral wall 2B. The retainer ring 3 is formed from a resin material having high rigidity.
In addition, the retainer ring 3 may be formed integrally with the top ring main body 2.

In the space defined inside the top ring main body 2 and the retainer ring 3 integrally fixed to the top ring main body 2, a substantially cylindrical shape in which the elastic film 4 and the outer peripheral portion of the elastic film 4 are held. Of the elastic membrane supporting member 5 are accommodated. A pressure sheet 6 made of an elastic film is stretched between the elastic film supporting member 5 and the top ring main body 2. The top ring body 2, the elastic film 4, and the pressure sheet 6
Thus, a fluid chamber 8 having an airtight structure is formed. The elastic film 4 and the pressure sheet 6 are made of ethylene propylene rubber (E
(PMD), polyurethane rubber, silicon rubber, and the like, and is formed of a rubber material having excellent strength and durability. A pressurized fluid such as pressurized air is supplied to the fluid chamber 8 via a fluid passage 10 including a tube and a connector. The pressure of the pressurized fluid supplied to the fluid chamber 8 is made variable by a regulator or the like. Elastic membrane 4
Outer peripheral surface, top ring body 2 and retainer ring 3
The elastic film 4 and the elastic film supporting member 5 are vertically movable with respect to the top ring body 2 and the retainer ring 3. In order to obtain higher polishing performance, it is desirable to form the fluid chamber 8 with an elastic film as in the present embodiment. However, without providing the elastic film 4, the object to be polished is directly pressed with a fluid. Is also good. In this case, a fluid chamber is formed by the internal space of the top ring main body 2 and the back surface of the semiconductor wafer to be polished.

An annular stopper plate 13 is provided on the upper plate 2A of the top ring body 2 via a support 12.
Has been fixed. Upper end surface 13 of stopper plate 13
a is set at a predetermined height position, and the stopper plate 13 constitutes a regulating member. When a pressurized fluid such as pressurized air is supplied to the fluid chamber 8, the elastic film 4 and the elastic film supporting member 5 move downward with respect to the top ring body 2 integrally. When the upper end 5a of the membrane support member 5 is engaged with the upper end surface 13a of the stopper plate 13, the downward movement is restricted to a predetermined range.

A chucking plate 14 having a plurality of through holes 14h is provided inside the elastic membrane supporting member 5. In this embodiment, the chucking plate 14 is fixed inside the elastic membrane supporting member 5, but the chucking plate 14 may be formed integrally with the elastic membrane supporting member 5. On the lower surface of the chucking plate 14, a number of spherical concave portions 14a are formed. Then, when the fluid chamber 8 is connected to a vacuum source via the fluid path 10, as shown in FIG. 2, the inside of the fluid chamber 8 becomes negative pressure, and the elastic film 4 is deformed so as to follow the concave portion 14a, That is, the portion of the elastic film 4 corresponding to the concave portion 14a becomes a suction cup, and the semiconductor wafer W is sucked to the lower surface of the elastic film 4.

The upper plate 2A of the top ring body 2 is provided with a plurality of stoppers 17 driven by an actuator 16 such as an air cylinder. That is, by operating the actuator 16, the stopper 17 is projected downward by a predetermined amount as shown in FIG.
When the internal pressure becomes negative, the elastic membrane supporting member 5 rises together with the elastic membrane 4, but when the upper end 5 a of the elastic membrane supporting member 5 comes into contact with the stopper 17, the elastic membrane supporting member 5 and the elastic membrane 4 Is regulated within a predetermined range. That is, the stopper 17 forms a regulating member whose height can be adjusted. If the actuator 16 is constituted by a mechanism capable of obtaining a variable pressing force such as an air cylinder, and the stopper 17 is projected during polishing to press the elastic film supporting member 5 downward, the outer peripheral portion of the semiconductor wafer W is mechanically moved. Can be pressed against the polishing surface. A top ring drive shaft 18 is provided above the upper plate 2 </ b> A of the top ring body 2, and the top ring body 2 and the top ring drive shaft 18 are connected by a universal joint 19.

The universal joint 19 for transmitting the pressing force and the rotational force while allowing the top ring drive shaft 18 to tilt to the top ring body 2 allows the top ring body 2 and the top ring drive shaft 18 to tilt each other. It has a spherical bearing mechanism that enables the rotation and a rotation transmission mechanism that transmits the rotation of the top ring drive shaft 18 to the top ring main body 2. The spherical bearing mechanism includes a spherical concave portion 18a formed at the center of the lower surface of the top ring drive shaft 18, a spherical concave portion 2a formed at the center of the upper surface of the upper plate 2A, and an interposition between the concave portions 18a. And a bearing ball 21 made of a high hardness material such as ceramics.

The rotation transmitting mechanism includes a top ring drive shaft 18.
And a driven pin (not shown) fixed to the upper plate 2A. Even if the top ring body 2 is inclined, the driven pin and the driving pin are relatively fixed. Since it is movable in the vertical direction, the contact points are shifted and engaged with each other, and the rotational torque of the top ring drive shaft 18 is reliably transmitted to the top ring body 2.

Next, the operation of the top ring 1 configured as described above will be described. By placing the entire top ring 1 at the transfer position of the semiconductor wafer and connecting the fluid chamber 8 to a vacuum source via a fluid path 10, the elastic film 4 is deformed as shown in FIG. The semiconductor wafer W is attracted to the lower surface of the film 4. Then, the semiconductor wafer W
The top ring 1 is moved in a state of adsorbing the semiconductor wafer W and the retainer ring with the entire top ring 1 positioned above a polishing table (reference numeral 30 in FIG. 7) having a polishing surface (for example, a polishing pad). 3 is pressed against the polishing surface to start polishing. The outer peripheral edge of the semiconductor wafer W is held by the retainer ring 3 so that the semiconductor wafer W does not protrude from the top ring 1.

When polishing the semiconductor wafer W, the air cylinder (reference numeral 33 in FIG. 7) connected to the top ring drive shaft 18 is operated to move the retainer ring 3 fixed to the lower end of the top ring main body 2 to a predetermined position. Is pressed against the polishing surface of the polishing table. In this state, a pressurized fluid having a predetermined pressure is supplied to the fluid chamber 8 to press the semiconductor wafer W against the polishing surface of the polishing table. In this case, the polishing pressure applied to the semiconductor wafer W is adjusted to a desired value by adjusting the pressure of the pressurized fluid applied to the fluid chamber 8. In this case, since the pressing force is applied to the semiconductor wafer W from the fluid in the fluid chamber 8, the polishing pressure is uniform over the entire surface of the semiconductor wafer W from the central portion to the peripheral edge regardless of the thickness of the semiconductor wafer W. Can be added. Therefore, the entire surface of the semiconductor wafer W can be uniformly polished.

Since a pressing force substantially equal to or slightly larger than the polishing pressure applied to the semiconductor wafer W is applied to the retainer ring 3 via the air cylinder, the polished surface around the semiconductor wafer W is substantially the same as the semiconductor wafer W. , And the pressure distribution from the central portion of the semiconductor wafer W to the peripheral portion and further to the outer peripheral portion of the retainer ring 3 outside the semiconductor wafer W becomes continuous and uniform. for that reason,
It is possible to prevent the polishing amount from being excessive or insufficient at the peripheral portion of the semiconductor wafer W to be polished.

FIG. 3 is a longitudinal sectional view showing a second embodiment of the substrate holding device of the present invention. In the present embodiment, the chucking plate 14 is not provided, and the inside of the elastic membrane supporting member 5 is a space. Instead, a plurality of through holes 4h are formed in the elastic film 4 from the central portion of the elastic film 4 to an intermediate portion between the central portion and the outer peripheral portion.
Therefore, when the semiconductor wafer W is attracted to the lower surface of the elastic film 4, the fluid chamber 8 is connected to a vacuum source via the fluid path 10, so that the pressure inside the fluid chamber 8 becomes negative and the semiconductor wafer W penetrates. Vacuum suction is performed by the suction action of the hole 4h. In the top ring 1 of the present embodiment, since the through-hole 4h is closed by the semiconductor wafer W to be polished during polishing, the operation during polishing is exactly the same as that of the top ring 1 shown in FIG.

According to the top ring constituting the substrate holding device shown in FIGS. 1 to 3, the retainer ring 3 is provided integrally with the rigid top ring main body 2, and the retainer ring 3 is moved up and down by the top ring main body 2. Move up and down. Thereby, the pressing force applied to the top ring main body 2 is used as the pressing force applied to the retainer ring 3, and unnecessary left and right (radial) movements of the retainer ring 3 are eliminated by the integral structure with the top ring main body 2. it can. Therefore, the distance between the retainer ring 3 and the peripheral portion (edge portion) of the semiconductor wafer W can always be minimized,
Polishing uniformity and polishing stability at the outer peripheral portion of the semiconductor wafer W can be improved.

Further, since the retainer ring 3 is formed integrally with the top ring main body 2, a highly rigid retainer ring structure is enabled, and the stability of the behavior of the retainer ring during polishing can be obtained. And, inside the stable high-rigidity retainer ring structure, the floating structure of the wafer holding and pressing mechanism follows the undulation of the polished surface, and as a result, the behavior of the retainer ring is stabilized on the hard polished surface,
The polishing stability of the semiconductor wafer is obtained.

Further, the stopper 17 is driven by a cylinder mechanism, and the stopper 17 is fixed at a fixed position, whereby the rise of the elastic film supporting member 5 is regulated to a predetermined height, and the rise of the chucking plate 14 is fixed. Hold in range. Thus, it is possible to prevent the semiconductor wafer from being warped more than necessary when the semiconductor wafer is attracted, and to solve quality problems such as breakage of the semiconductor wafer. Further, if the stopper 17 is projected by the cylinder mechanism and the elastic film supporting member 5 is pressed downward during polishing, the pressing pressure of the semiconductor wafer W against the polished surface is partially changed, and the profile of the surface to be polished is optionally changed. Polishing characteristics can be obtained.

According to the top ring constituting the substrate holding device shown in FIG. 3, a plurality of through holes 4h are formed in the elastic film 4 so that the elastic film 4 is directly vacuum-pressured when the semiconductor wafer W is sucked. The elastic film 4 does not come into contact with the chucking plate 14 (shown in FIG. 1) because the semiconductor wafer W is attracted to the semiconductor wafer W.
The stability of polishing uniformity increases. In addition, the suction of the semiconductor wafer W by the action of the suction cup using the chucking plate 14 becomes unnecessary, so that the chucking plate 14 does not need to be provided, and only the ring-shaped elastic film support member 5 is required.

FIGS. 4 to 6 are views showing examples in which grooves are formed on the lower surface of the retainer ring. FIGS.
(A) and FIG. 6 (a) are bottom views of the retainer ring, and FIG. 4 (b), FIG. 5 (b) and FIG.
FIG. 7A is a sectional view taken along line AA of FIG. 5A and FIG. In the example shown in FIG. 4, a plurality of grooves 3 g-1 extending radially (in the radial direction r) are formed on the bottom surface of the retainer ring 3. In the example shown in FIG. 5, a plurality of grooves 3g-2 inclined at a predetermined angle (θ) with respect to the radial direction r are formed on the bottom surface of the retainer ring 3. In the example shown in FIG. 6, a plurality of grooves 3g-3 extending radially (in the radial direction r) from the outer peripheral edge to slightly before the inner peripheral edge are formed on the bottom surface of the retainer ring 3.

When the entire bottom surface of the retainer ring is flat, the retainer ring presses a polishing surface such as a polishing pad, so that the polishing liquid (slurry) can easily enter the inside of the retainer ring. Insufficient supply of the polishing liquid to the wafer results in a problem that the polishing uniformity of the semiconductor wafer deteriorates and the polishing rate decreases. Also,
Because the polishing liquid between the semiconductor wafer and the polishing surface decreases,
There is also a problem that friction between the semiconductor wafer and the polished surface increases, and the power load on the polishing apparatus increases. In order to prevent this, it is conceivable to reduce the width of the retainer ring so as to prevent the polishing liquid from flowing into the inside of the retainer ring as much as possible. Since the portion becomes small, it becomes difficult to press the polished surface stably with the retainer ring. In addition, since the amount of wear of the retainer ring increases, the life of the retainer ring is shortened.

In the present invention, as shown in FIG. 4, by providing a plurality of grooves 3g-1 on the contact surface side of the retainer ring 3 with the polishing surface, the polishing liquid can easily enter the inside of the retainer ring 3. The supply of the polishing liquid to the semiconductor wafer can be ensured, and the deterioration of the polishing uniformity and the reduction of the polishing rate caused by the shortage of the polishing liquid can be prevented. Further, as shown in FIG. 5, the groove 3g is aligned with the rotation direction R of the retainer ring 3.
-2 is inclined with respect to the radial direction, so that the polishing liquid can be more easily entered. In a case where there is a high possibility that polishing is locally accelerated due to excessive pouring of the polishing liquid, as shown in FIG. 6, a groove 3g-3 which does not form a groove to the inner peripheral portion of the retainer ring 3 and leaves a wall. By controlling the entry of the polishing liquid, it is possible to suppress the local overpolishing of the semiconductor wafer while ensuring the supply of the polishing liquid to the semiconductor wafer inside the retainer ring 3. Also, if a groove is formed up to the inner peripheral portion of the retainer ring, when the top ring, which is a polishing head, and the semiconductor wafer rotate relatively during polishing, the corners and notches of the orientation flat of the semiconductor wafer are formed. The groove contacts the retainer ring, and the impact tends to cause uneven wear around the groove inside the retainer ring. In particular, this tendency is remarkable in the case of the orientation flat, and a sound is produced by the impact of the contact. This uneven wear can be prevented by leaving a wall at the end of the groove of the retainer ring as shown in FIG.

The formation of the groove on the lower surface of the retainer ring is not limited to the top ring of the embodiment shown in FIGS. 1 to 3, but may be applied to any top ring having a structure in which the retainer ring is pressed against the polished surface. FIG. 7 shows a specific example of the top ring. In the example shown in FIG. 7, the top ring 101 includes a top ring main body 102 and a holding plate 103 that holds an upper surface of an object to be polished such as a semiconductor wafer W. The holding plate 103 is made of a highly rigid material such as ceramics, so that the wafer holding surface 103a is not deformed. An elastic mat 106 is attached to the lower surface of the holding plate 103.

A retainer ring (guide ring) 107 for holding the outer peripheral portion of the semiconductor wafer W for holding the semiconductor wafer W on the lower surface of the holding plate 103 is arranged on the outer peripheral portion of the top ring 101. A chamber C is formed between the holding plate 103 and the top ring main body 102. The chamber C supplies a fluid to the lower surface of the holding plate 103 through a communication hole 103m formed in the holding plate 103. It is for.
That is, by supplying a pressurized fluid such as compressed air to the chamber C, the pressurized fluid is ejected from the wafer holding surface 103 a of the holding plate 103, and a backside pressure can be applied to the semiconductor wafer W. By evacuating the chamber C with a vacuum pump, the holding plate 10
The semiconductor wafer W can be vacuum-sucked on the third wafer holding surface 103a. When the semiconductor wafer W is separated from the wafer holding surface 103a of the holding plate 103, a liquid such as pure water is supplied to the chamber C.

In the embodiment shown in FIG. 7, the semiconductor wafer held on the lower surface of the top ring is pressed against the polishing surface by an air cylinder that moves the top ring drive shaft 18 up and down. Then, a retainer ring 107 having a groove 103g-3 provided on the lower surface is arranged so as to surround the semiconductor wafer.
The retainer ring 107 is pressed independently against the polishing surface. The space 143 is formed by the seal rings 140A and 140B. The lower seal ring 140A includes a ring 141a for pressing the retainer ring 107, and a lip seal 142a for sealing between the ring 141a and the holding plate 103 and between the ring 141a and the top ring main body 102. . The upper seal ring 140B includes a ring 141b fixed to the mounting flange portion 102a of the top ring main body 102, a lip seal 142b for sealing between the ring 141b and the holding plate 103, and between the ring 141b and the top ring main body 102. It consists of The retainer ring 107 shown in FIG. 7 includes a first retainer ring member 107a and a second retainer ring member 107b.

In the top ring shown in FIG. 7, a retainer ring pressing mechanism is provided at the mounting flange portion 102a of the top ring main body 102. That is, the seal ring 1 is provided at the location of the mounting flange portion 102a.
A space 143 formed by 40A and 140B is provided. Therefore, in the embodiment shown in FIG. 7, even if the retainer ring 107 is worn, the retainer ring pressing mechanism can press the retainer ring 107 with a desired pressing force. The groove 103g-3 formed in the retainer ring 107 is a groove in which a wall is left like the groove 3g-3 shown in FIG. The action of the groove 103g-3 is as described in relation to the groove 3g-3 shown in FIG. The groove 103g-3 may be formed to be inclined at a predetermined angle (θ) with respect to the radial direction r as shown in FIG.

FIG. 8 is a sectional view showing the overall configuration of a polishing apparatus provided with the substrate holding device shown in FIGS. In the figure, reference numeral 1 denotes a top ring constituting the substrate holding device. Below the top ring 1, a polishing table 30 having a polishing pad 31 on an upper surface is provided. The top ring 1 is connected to a top ring drive shaft 18 via a universal joint 19, and the top ring drive shaft 18 is connected to a top ring vertical air cylinder 33 fixed to a top ring head 32. The top ring drive shaft 18 is moved up and down by the top ring up / down air cylinder 33 to raise and lower the entire top ring 1 and press the retainer ring 3 fixed to the lower end of the top ring body 2 against the polishing table 30. It has become.

The top ring drive shaft 18 is connected to a rotary cylinder 34 via a key (not shown). The rotary cylinder 34 has a timing pulley 35 on its outer periphery. The timing pulley 35 is connected via a timing belt 36 to a timing pulley 38 provided on a top ring motor 37 fixed to the top ring head 32. Therefore, the timing pulley 38, the timing belt 36, and the timing pulley 3 are driven by rotating the top ring motor 37.
5, the rotary cylinder 34 and the top ring drive shaft 18 rotate integrally, and the top ring 1 rotates. The top ring head 32 is supported by a top ring head shaft 39 fixedly supported by a frame (not shown).

The top ring vertical air cylinder 33 and the fluid chamber 8 are connected to the compressed air source 24 via regulators R1 and R2, respectively. Then, by adjusting the air pressure of the pressurized air supplied to the top ring vertical air cylinder 33 by the regulator R1, the pressing force of the retainer ring 3 pressing the polishing pad 31 can be adjusted, and the fluid chamber is adjusted by the regulator R2. The polishing pressure for pressing the semiconductor wafer W against the polishing pad 31 can be adjusted by adjusting the air pressure of the pressurized air supplied to 8.

A polishing liquid supply nozzle 40 is provided above the polishing table 30.
Thus, the polishing liquid Q is supplied onto the polishing pad 31 on the polishing table 30.

In the polishing apparatus having the above structure, the semiconductor wafer W is held on the lower surface of the elastic film 4 of the top ring 1, and the retainer ring 3 integrally fixed to the top ring 1 by operating the top ring vertical air cylinder 33.
Is pressed toward the polishing table 30 and pressurized air is supplied to the fluid chamber 8 to press the semiconductor wafer W against the polishing pad 31 on the upper surface of the rotating polishing table 30. On the other hand, by flowing the polishing liquid Q from the polishing liquid supply nozzle 40, the polishing liquid Q is held on the polishing pad 31, and the polishing liquid Q is provided between the polishing surface (the lower surface) of the semiconductor wafer W and the polishing pad 31. Is polished in a state where there is.

The pressing force of the retainer ring 3 on the polishing pad 31 by the top ring vertical air cylinder 33 and the pressing force of the semiconductor wafer W on the polishing pad 31 by the pressurized air supplied to the fluid chamber 8 are appropriately adjusted. Semiconductor wafer W
Is polished. During polishing, the pressing force of pressing the semiconductor wafer W against the polishing pad 31 on the polishing table 30 can be changed by the regulator R2, and the pressing force of the retainer ring 3 pressing the polishing pad 31 can be changed by the regulator R1. Therefore, during polishing, by appropriately adjusting the pressing force of the retainer ring 3 pressing the polishing pad 31 and the pressing force of pressing the semiconductor wafer W against the polishing pad 31,
The distribution of the polishing pressure from the central portion of the semiconductor wafer W to the peripheral portion and further to the outer peripheral portion of the retainer ring 3 outside the semiconductor wafer W becomes continuous and uniform. Therefore, it is possible to prevent the polishing amount at the peripheral portion of the semiconductor wafer W from being excessive or insufficient.

In the present invention, the polishing surface formed on the polishing table may be formed by the above-mentioned polishing pad, or may be formed by fixed abrasive grains. There are various types of polishing pads available on the market, for example, SUBA800, IC-IC manufactured by Rodale.
1000, IC-1000 / SUBA400 (double layer cloth), Surfin manufactured by Fujimi Incorporated
xxx-5, Surfin 000, etc. SUB
A800, Surfin xxx-5, Surfin
000 is a non-woven fabric obtained by hardening fibers with urethane resin.
C-1000 is a rigid foamed polyurethane (single layer). The foamed polyurethane is porous and has many fine dents or pores on its surface.

The fixed abrasive is a plate formed by fixing the abrasive in a binder. Polishing proceeds with abrasive grains spontaneously generated from the fixed abrasive grains. The fixed abrasive is composed of an abrasive, a binder, and pores.
Cerium oxide (CeO ₂ ) of 5 μm or less, and an epoxy resin is used for the binder. The fixed abrasive forms a hard polished surface. The fixed abrasive grains include, in addition to the above-mentioned plate-shaped abrasive grains, fixed abrasive grains pads having a two-layer structure in which an elastic polishing pad is attached below a thin fixed abrasive layer. Another hard polished surface is the IC-1000.

The top ring of the present invention constitutes a hard polished surface, and particularly has a compression elastic modulus of 19.6 MPa (200 kPa).
g / cm ² ) or more.
In an example of a conventional top ring, a semiconductor wafer is held on a rigid top ring main body via a backing pad. However, since the polishing pad has elasticity, the impact on the semiconductor wafer is also absorbed on the polishing pad side. However, when the polished surface becomes a hard polished surface, the unevenness of the polished surface is transferred to the semiconductor wafer as it is, which has an effect. Further, the holes for vacuum suction of the semiconductor wafer on the top ring side were transferred to the back surface of the semiconductor wafer. However, according to the top ring that holds the semiconductor wafer by the fluid pressure via the elastic film, the unevenness of the hard polished surface can be absorbed by the fluid pressure applied to the back surface of the semiconductor wafer. Therefore, the polishing performance is good even when a hard polishing surface is used, and the vacuum suction holes of the backing pad are not transferred to the semiconductor wafer. Further, according to the present invention, since the retainer ring is formed integrally with the top ring main body, the rigidity is high, and the unstable movement of the retainer ring more than necessary is suppressed, and the polishing performance is stabilized.

After supporting the semiconductor wafer with the top ring of the present invention and polishing it with hard fixed abrasive grains, the same top ring,
In other words, while the semiconductor wafer is supported by a top ring that holds the semiconductor wafer at a fluid pressure, finish polishing is performed on a polishing pad that is softer than fixed abrasive grains, so that polishing is performed with higher flatness and less scratches. Face can be obtained. Here, soft means that the elastic modulus is low. FIG. 9 is a plan view showing a polishing apparatus suitable for performing the above-described two-stage polishing using the top ring of the present invention. The polishing apparatus shown in FIG. 9 includes two polishing tables 30, and a fixed polishing grain 29 is attached to one of the polishing tables 30.
a, and a polishing pad 31
Is attached to constitute the second polishing unit 41b. The second polishing unit 41b can be used as a finish polishing unit. The top ring 1 has the configuration shown in FIGS. The first polishing unit 41a and the second polishing unit 41b share one top ring 1. That is, the top ring 1 is supported by the top ring head 32 similarly to the example shown in FIG. 8, and the top ring head 32 is swingable by the top ring head shaft 39.
Is movable between the fixed abrasive grains 29 and the polishing pad 31. In this embodiment, the semiconductor wafer W is provided by a pusher 42 → a top ring 1 → a first polishing unit 41a.
(Fixed abrasive grains 29) → second polishing unit 41b (polishing pad 31) → pusher 42. With this configuration, after the semiconductor wafer W is supported by the top ring 1 and polished with the hard fixed abrasive grains 29, the top ring 1 is moved onto the polishing pad 31 to finish on the polishing pad softer than the fixed abrasive grains. Can be polished. Therefore, a polished surface with higher flatness and less scratches can be obtained.

[0053]

According to the present invention, the retainer ring is provided integrally with the rigid top ring main body, and the retainer ring is moved up and down by the vertical movement of the top ring main body. Thus, the pressing force on the top ring main body is used as the pressing force on the retainer ring, and unnecessary left and right (radial) movements of the retainer ring can be eliminated by the integral structure with the top ring main body. Therefore, it is possible to always minimize the distance between the retainer ring and the peripheral portion (edge portion) of the substrate to be polished, and to improve the uniformity of polishing and the stability of polishing at the outer peripheral portion of the substrate. be able to.

By making the retainer ring integral with the top ring main body, a highly rigid retainer ring structure is enabled, and the stability of the behavior of the retainer ring during polishing can be obtained. Then, inside the stable and high-rigidity retainer ring structure, the floating structure of the substrate holding and pressing mechanism follows the undulations of the polished surface, and as a result, the behavior of the retainer ring on the hard polished surface is stabilized, and Is obtained.

Further, the regulating member is driven by a driving mechanism such as a cylinder mechanism and the like, and the regulating member is fixed at a fixed position to regulate the elevation of the supporting member for supporting the elastic film to a predetermined height, and the holding plate is held. To a certain range. Thereby, it is possible to prevent the substrate from being warped more than necessary at the time of sucking the substrate, and to solve quality problems such as breakage of the substrate. In addition, if the stopper is projected by the cylinder mechanism and the elastic film supporting member is pressed downward during polishing, the pressing pressure on the polishing surface of the substrate is partially changed, and an arbitrary polishing characteristic with respect to the profile of the surface to be polished is obtained. Obtainable.

The top ring of the present invention has an especially hard polished surface, especially a compression elastic modulus of 19.6 MPa (200 kg / c).
Excellent in compatibility with a polished surface of m ² ) or more. According to the top ring of the present invention, since the substrate is held by the fluid pressure via the elastic film inside the highly rigid retainer ring, the unevenness of the hard polished surface is absorbed by the fluid pressure applied to the back surface of the substrate. it can. Therefore, even when a hard polishing surface is used, the polishing performance is good, and the vacuum suction holes of the backing pad are not transferred to the substrate.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a substrate holding device of the present invention.

FIG. 2 is a longitudinal sectional view showing an operation state of the substrate holding device shown in FIG.

FIG. 3 is a longitudinal sectional view showing a second embodiment of the substrate holding device of the present invention.

FIG. 4 is a diagram showing an example in which a groove is formed on a lower surface of a retainer ring, and FIG. 4 (a) is a bottom view of the retainer ring, and FIG.
FIG. 4B is a sectional view taken along line AA of FIG.

5A and 5B are diagrams showing an example in which a groove is formed on the lower surface of the retainer ring, and FIG. 5A is a bottom view of the retainer ring, and FIG.
FIG. 5B is a sectional view taken along line AA in FIG.

6A and 6B are diagrams showing an example in which a groove is formed on the lower surface of the retainer ring, and FIG. 6A is a bottom view of the retainer ring, and FIG.
FIG. 7B is a sectional view taken along line AA of FIG.

FIG. 7 is a longitudinal sectional view showing another embodiment of the substrate holding device of the present invention.

FIG. 8 is a cross-sectional view showing the overall configuration of a polishing apparatus provided with the substrate holding device shown in FIGS. 1 to 3;

FIG. 9 is a plan view showing a polishing apparatus suitable for performing two-stage polishing using the substrate holding device of the present invention.

FIG. 10 is a schematic diagram of a substrate holding apparatus having a structure in which a semiconductor wafer is pressed against a polishing surface by fluid pressure such as air pressure and a retainer ring is pressed against a polishing surface by fluid pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,101 Top ring 2,102 Top ring main body 2A Upper plate 2B Peripheral wall 3,53,107 Retainer ring 3g-1,3g-2,3g-3,103g-3 Groove 4 Elastic film 4h Through hole 5 Elastic film support Member 5a Upper end portion 6 Pressurizing sheet 8 Fluid chamber 10 Fluid path 12 Support 13 Stopper plate 13a Upper end surface 14 Chucking plate 14a Depression 16 Actuator 17 Stopper 18 Top ring drive shaft 19 Universal joint 21 Bearing ball 24 Compressed air source 29 Fixed Abrasive grains 30 Polishing table 31 Polishing pad 32 Top ring head 33 Air cylinder for top ring up and down 34 Rotating cylinder 35, 38 Timing pulley 36 Timing belt 37 Motor for top ring 39 Top ring head shaft 40 Polishing liquid supply nozzle 41a, 41b Polishing unit 42 Pusher 52 Wafer pressing mechanism 54 Retaining ring pressing mechanism 55 Drive shaft 103 Holding plate 103a Wafer holding surface 106 Elastic mat 107a, 107b Retaining ring members 140A, 140B Seal rings 141a, 141b Rings 142a, 142b Lip Seal 143 space C chamber W semiconductor wafer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Keisuke Namiki 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Works Co., Ltd. (72) Inventor Hiroshi Yoshida 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Stock F term in EBARA CORPORATION (reference) 3C058 AA07 AB04 CB01 DA12 DA17

Claims (20)

[Claims] 1. A substrate holding apparatus for holding a substrate to be polished and pressing the substrate against a polishing surface on a polishing table, wherein the top ring main body holds the substrate and the top ring main body is fixed to or integrated with the top ring main body. A retainer ring provided on the top ring body and holding a peripheral edge of the substrate, and a fluid chamber provided in the top ring main body and covered with an elastic film and supplied with fluid, by supplying a pressurized fluid into the fluid chamber. The substrate holding device, wherein the substrate is pressed against the polishing surface via the elastic film, and the retainer ring is pressed against the polishing surface by applying a pressing force to the top ring body. 2. The substrate holding apparatus according to claim 1, wherein a polishing pressure applied to the substrate is adjusted by adjusting a pressure of a pressurized fluid supplied to the fluid chamber. 3. The elastic film is supported by a support member so as to be vertically movable within the top ring main body, and a vertical position of the support member with respect to the top ring main body is regulated by a regulating member. Item 3. The substrate holding device according to item 1 or 2. 4. The substrate holding device according to claim 3, wherein the position of said regulating member is adjustable. 5. A holding plate having a plurality of concave portions is provided in the fluid chamber, and the elastic film is deformed so as to follow the concave portion of the holding plate by applying a negative pressure to the fluid chamber. The substrate holding device according to any one of claims 1 to 4, wherein the substrate is sucked by means of: 6. The substrate according to claim 1, wherein a through-hole is provided in the elastic film, and the substrate is adsorbed by the elastic film by applying a negative pressure to the fluid chamber.
13. The substrate holding device according to item 13. 7. A substrate holding apparatus for holding a substrate to be polished and pressing the substrate against a polishing surface on a polishing table, wherein the top ring main body holds the substrate and the top ring main body is fixed to or integrated with the top ring main body. A retainer ring that is provided in the top ring and holds an outer peripheral edge of the substrate, and a fluid chamber that is provided in the top ring main body and is supplied with fluid,
By supplying a pressurized fluid into the fluid chamber, the substrate is pressed against the polishing surface by fluid pressure, and the retainer ring is pressed against the polishing surface by applying a pressing force to the top ring body. A substrate holding device characterized by the above-mentioned. 8. The substrate holding apparatus according to claim 1, wherein the means for applying a pressing force to the top ring main body comprises a mechanism for moving the top ring main body up and down. 9. A polishing table having a polishing surface, a top ring for holding a substrate to be polished and pressing against the polishing surface on the polishing table, wherein the polishing surface is formed by a hard polishing member, A fluid chamber formed of an elastic film is provided in the top ring, and the substrate is pressed against the hard polishing surface via the elastic film by supplying a pressurized fluid into the fluid chamber. Characteristic polishing equipment. 10. A polishing table having a polishing surface formed of a softer polishing member than the hard polishing member, wherein the substrate is polished by the hard polishing member, and then the softened surface is polished by the pressurized fluid. The polishing apparatus according to claim 9, wherein the polishing is performed by pressing against a polishing surface formed by the polishing member. 11. The top ring includes a retainer ring fixed to or integral with the top ring main body and holding an outer peripheral edge of the substrate, and the retainer ring is formed by applying a pressing force to the top ring main body. 10. The polishing apparatus according to claim 9, wherein the polishing apparatus is pressed against a polishing surface. 12. The hard polishing member may be 19.6MP.
a (200kg / cm ²⁾ or more to have a compressive modulus polishing apparatus according to claim 9, wherein. 13. The polishing apparatus according to claim 12, wherein said hard polishing member is constituted by fixed abrasive grains formed in a plate shape by fixing abrasive grains in a binder. 14. A polishing table having a polishing surface, a top ring for holding a substrate to be polished and pressing against a polishing surface on the polishing table, wherein the polishing surface is formed of a hard polishing member, A polishing apparatus, wherein a fluid chamber is provided in the top ring, and the substrate is pressed against the polishing surface by fluid pressure by supplying a pressurized fluid into the fluid chamber. 15. A polishing table having a polishing surface formed of a softer polishing member than the hard polishing member, further comprising: polishing the substrate with the hard polishing member; The polishing apparatus according to claim 14, wherein the polishing is performed by pressing against a polishing surface formed by the polishing member. 16. A polishing table having a polishing surface, and a substrate holding apparatus according to claim 1, which holds a substrate to be polished and presses the substrate against the polishing surface on the polishing table. A polishing apparatus, comprising: 17. A polishing table having a polishing surface, a top ring for holding a substrate and pressing the polishing table, and a retainer ring for pressing a polishing surface around the substrate.
A polishing apparatus, wherein a groove extending from the outside to the inside is provided on a lower surface of the retainer ring, and the groove is not formed up to an inner peripheral portion of the retainer ring, and a wall is left. 18. The polishing apparatus according to claim 17, wherein said groove is inclined with respect to a radial direction. 19. A polishing method comprising: a polishing table having a polishing surface; and a top ring, wherein the top ring holds a substrate to be polished and presses the substrate against the polishing surface on the polishing table to polish the substrate. A polishing method, wherein a pressurized fluid is supplied to a fluid chamber provided in the top ring, whereby the substrate is pressed against a polishing surface formed of a hard polishing member by fluid pressure and polished. 20. A polishing table having a polishing surface formed of a softer polishing member than the hard polishing member, wherein the substrate is polished by the hard polishing member, and the soft surface is polished by the fluid pressure. The polishing method according to claim 19, wherein the polishing is performed by pressing against a polishing surface formed by the polishing member.