JP7345433B2 - Polishing head and wafer single-sided polishing method - Google Patents

Description

The present invention relates to a polishing head and a method for polishing one side of a wafer.

In order to control the edge flatness of a silicon wafer, it is necessary to control the load applied near the edge. With conventional polishing heads that have a retainer ring structure, it was possible to reduce the amount of roll-off at the edge by reducing the load due to the retainer effect. It was not possible to properly control the load.

For example, Patent Document 1 describes a polishing head and a polishing processing apparatus. Patent Document 1 discloses that when polishing one side of a wafer, the amount of polishing at the edge of the wafer becomes uneven and the ESFQR deteriorates, so the pressure at the outer peripheral retainer part of the polishing head is set to a pressure different from the polishing head pressure (correction pressure). In addition, it is described that the tilt angle of the polishing head is corrected, whereby the polishing head and polishing processing apparatus of Patent Document 1 can flatten the wafer or equalize the amount of polishing within the surface.

In addition, Patent Document 2 focuses on the problem that when polishing one side of a wafer, the polishing amount is larger than the center part due to stress concentration and slurry inflow at the edge part, which tends to cause sagging. A polishing head having a membrane and a retainer ring for separately controlling edge pressure, a wafer polishing apparatus, and a polishing method are described.

For example, even in the case of a zone pressure head in which an air bag for pressurizing a wafer is divided into zones in order to control the load applied near the edge portion as described in Patent Documents 1 and 2, the load distribution is not designed. This tendency was particularly noticeable near the edges, and the controllability was poor.

Japanese Patent Application Publication No. 2018-171670 JP 2019-201127 Publication

An example of a conventional polishing head will be described with reference to FIG.
A polishing head 10' whose cross-sectional view is shown in FIG. 8 includes an upper metal 2 and a flange 3 joined above the upper metal 2. The upper metal 2 includes a ring-shaped protrusion 2a on the outer periphery on the opposite side from the flange 3.

The polishing head 10' further includes a retainer ring 4' below the upper metal 2. The retainer ring 4' is disposed at a position corresponding to the ring-shaped protrusion 2a of the upper metal 2, and similarly has a ring-shaped planar shape.

A ring-shaped retainer ring pressurizing part 41' is arranged between the ring-shaped projection part 2a and the retainer ring 4'.

A back plate 22 is arranged inside the retainer ring 4'. The back plate 22 and the upper metal 2 define a wafer pressure section 21 therebetween. A back plate stopper 22a is arranged at the upper part of the outer circumference of the back plate 22.

The polishing head 10' further includes, below the retainer ring 4', a template guide ring 5 having a planar shape similar to that of the retainer ring 4'. Further, a back pad 24 having a planar shape similar to that of the upper metal 2 is arranged between the retainer ring 4' and the template guide ring 5. Back pad 24 and back plate 22 define a fluid enclosure 23 therebetween.

In single-side polishing of a wafer using the polishing head 10' of FIG. 8, first, the wafer 100 is held inside the ring-shaped template guide ring 5. Next, by pressurizing the flange 3 to press the polishing head 10' against the polishing pad 200, and further introducing air into the wafer pressurizing section 21, the wafer 100 can be pressurized via the fluid sealing section 23.

The load due to the pressurization of the flange 3 is also transmitted to the retainer ring 4' via the retainer ring pressurizing portion 41'. The load received by the retainer ring 4' is transmitted to the template guide ring 5 via the back pad 24. The load applied to the template guide ring 5 is transmitted to the portion 200c of the polishing pad 200 that is in contact with the template guide ring 5, deforms it, and pushes the surface of this portion 200c downward.

By performing polishing with the polishing pad 200 with part 200c deformed, excessive load is suppressed near the edge 100E of the wafer 100 being polished, thereby preventing excessive polishing near the edge 100E. be able to. This effect becomes larger as the load applied to part 200c of polishing pad 200 becomes larger.

However, the pressing force of the flange 3 (head press) and the pressing force of the wafer 100 by the wafer pressurizing section 21 (back air press) are not completely independent. Therefore, even if an attempt is made to weaken the load applied to the vicinity of the edge portion 100E of the wafer 100 by increasing the load transmitted to the template guide ring 5 by increasing the head press when pressurizing the wafer, the load due to the back air press will also increase. However, there was a limit to the range of pressure adjustment.

The present invention was made to solve the above problems, and provides a polishing head that can control the load applied near the edge of the wafer independently of the load applied within the wafer surface, and a wafer polishing head using this polishing head. The purpose is to provide a single-sided polishing method.

In order to achieve the above object, the present invention performs polishing by holding a wafer and pressing the wafer against the polishing surface of a polishing pad while rotating the wafer within the polishing surface. A polishing head configured as follows,
has a pressure surface;
A retainer ring is provided on the outer periphery of the pressure surface side,
The retainer ring includes an outer retainer ring and an inner retainer ring located inside the outer retainer ring,
A portion of the pressing surface corresponding to the inside of the inner retainer ring is configured to press the wafer,
The polishing head is characterized in that the outer retainer ring and the inner retainer ring are configured to apply loads to the polishing pad independently of each other.

The polishing head of the present invention includes a retainer ring including an inner retainer ring and an outer retainer ring, and is configured such that the outer retainer ring and the inner retainer ring can apply a load to the polishing pad independently of each other. By doing so, the load from the outer retainer ring to the polishing pad can be increased independently without causing a change in the load within the wafer plane. That is, according to the polishing head of the present invention, the load applied near the edge of the wafer can be controlled independently of the load applied within the wafer surface. Thereby, the portion of the polishing pad that comes into sliding contact with the vicinity of the edge of the wafer during polishing can be deformed without changing the load value within the wafer surface. By deforming the polishing pad using such a two-stage retainer ring, it is possible to weaken the load near the wafer edge during polishing, reduce edge roll-off, and thereby reduce the amount of flatness deterioration at the wafer edge. reduction can be achieved.

Preferably, the polishing apparatus further includes a template guide ring configured to receive loads from the outer retainer ring and the inner retainer ring and transmit the loads to the polishing pad.

A polishing head equipped with such a template guide ring can reliably hold the wafer and control the load applied near the edge portion with high precision.

The present invention also provides a method for polishing one side of a wafer, comprising:
Using the polishing head of the present invention, holding a wafer on a portion of the pressurizing surface that corresponds to the inside of the inner retainer ring,
Applying a load to the polishing pad independently by the outer retainer ring and the inner retainer ring to deform the polishing pad,
The present invention provides a method for polishing one side of a wafer, comprising polishing the wafer with the deformed polishing pad while holding and pressurizing the wafer with the polishing head.

Since such a single-sided wafer polishing method uses the polishing head of the present invention, it is possible to perform single-sided polishing of the wafer while controlling the load applied near the edge of the wafer independently of the load applied within the wafer surface. can. Thereby, edge roll-off can be reduced, thereby achieving a reduction in the amount of flatness deterioration at the edge portion of the wafer.

As described above, with the polishing head of the present invention, the two-stage retainer ring allows the polishing pad to slide into contact with the vicinity of the edge of the wafer during polishing without changing the load value within the wafer surface. You can transform the part that is displayed. Thereby, during polishing, the load applied to the vicinity of the edge of the wafer can be controlled independently of the load applied within the wafer surface. As a result, by performing polishing using the polishing head of the present invention, edge roll-off can be reduced, and the amount of flatness deterioration at the edge portion of the wafer can be reduced.

Furthermore, with the single-side wafer polishing method of the present invention, it is possible to perform single-side polishing of the wafer while controlling the load applied near the edge of the wafer independently of the load applied within the wafer surface. Thereby, edge roll-off can be reduced, and the amount of flatness deterioration at the edge portion of the wafer can be reduced.

1 is a schematic cross-sectional view showing a polishing head according to an example of the present invention. FIG. 2 is a schematic plan view showing the positional relationship between an outer retainer ring, an inner retainer ring, and a part of a pressurizing surface of a polishing head according to an example of the present invention. FIG. 2 is a schematic diagram comparing deformation of a polishing pad by a polishing head according to an example of the present invention with deformation of a polishing pad by a conventional polishing head. 1 is a schematic diagram showing a method for polishing one side of a wafer according to an example of the present invention. It is a schematic sectional view showing load distribution measurement in an example and a comparative example. It is a graph showing load distribution in Examples and Comparative Examples. It is a graph showing changes in edge flatness in Examples and Comparative Examples. FIG. 2 is a schematic cross-sectional view showing an example of a conventional polishing head.

As mentioned above, there has been a need to develop a polishing head that can control the load applied near the edge of the wafer independently of the load applied within the wafer surface.

As a result of intensive studies on the above-mentioned problems, the present inventors have determined that the retainer ring is equipped with an inner retainer ring and an outer retainer ring, in other words, a double retainer ring, based on the structure of the conventional head. By configuring the retainer ring and the inner retainer ring to be able to apply loads to the polishing pad independently of each other, polishing can be performed independently from the outer retainer ring without causing any change in the load applied within the wafer surface. The present invention was completed based on the discovery that the load applied to the pad can be increased, and as a result, the load applied near the edge of the wafer can be controlled independently of the load applied within the wafer plane.

That is, the present invention provides a polishing device configured to hold a wafer, apply pressure to the wafer, press the wafer against the polishing surface of a polishing pad, and rotate the wafer within the polishing surface to perform polishing. A head,
has a pressure surface;
A retainer ring is provided on the outer periphery of the pressure surface side,
The retainer ring includes an outer retainer ring and an inner retainer ring located inside the outer retainer ring,
A portion of the pressing surface corresponding to the inside of the inner retainer ring is configured to press the wafer,
The polishing head is characterized in that the outer retainer ring and the inner retainer ring are configured to apply loads to the polishing pad independently of each other.

The present invention also provides a method for polishing one side of a wafer, comprising:
Using the polishing head of the present invention, holding a wafer on a portion of the pressurizing surface that corresponds to the inside of the inner retainer ring,
Applying a load to the polishing pad independently by the outer retainer ring and the inner retainer ring to deform the polishing pad,
The method of polishing one side of a wafer is characterized in that the wafer is polished by the deformed polishing pad while the wafer is held and pressed by the polishing head.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

[Polishing head]
First, an example of the polishing head of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view showing a polishing head according to an example of the present invention. FIG. 2 is a schematic plan view showing the positional relationship between the outer retainer ring, the inner retainer ring, and a part of the pressurizing surface of the polishing head according to an example of the present invention.

A polishing head 10 whose cross section is schematically shown in FIG. 1 has a substantially circular planar shape. The polishing head 10 includes an upper metal 2 and a flange 3 joined above the upper metal 2. An upper metal seal member 20 is disposed on the surface of the upper metal 2 opposite to the flange 3.

The polishing head 10 has a pressure surface 1 on the side opposite to the side to which the flange 3 is joined. The polishing head 10 further includes a retainer ring 4 on the outer periphery below the upper metal 2 on the pressure surface 1 side. The retainer ring 4 includes an outer retainer ring 4a and an inner retainer ring 4b located inside the outer retainer ring 4a, as shown in FIGS. 1 and 2. Therefore, the retainer ring 4 can also be called a double retainer ring.

The upper metal 2 is provided with an outer retainer ring pressurizing part 41, which is a space, at a position corresponding to the outer retainer ring 4a. Furthermore, an outer pressure section sealing member 42 made of a ring-shaped elastic body is disposed between the outer retainer ring pressure section 41 and the outer retainer ring 4a. The outer pressure section sealing member 42 is arranged to seal the outer retainer ring pressure section 41.

On the other hand, the portion of the upper metal 2 that corresponds to the inner retainer ring 4b is solid.

A back plate 22 is arranged inside the inner retainer ring 4b. The back plate 22 and the upper metal seal member 20 define a wafer pressurizing section 21, which is a space therebetween. Further, a back plate stopper 22a is arranged to seal the wafer pressurizing section 21.

The polishing head 10 further includes, below the retainer ring 4, a template guide ring 5 having a planar shape similar to that of the retainer ring 4. Further, a back pad 24 having a planar shape similar to that of the upper metal 2 is arranged between the retainer ring 4 and the template guide ring 5. Back pad 24 and back plate 22 define a fluid enclosure 23 therebetween.

The polishing head 10 can hold the wafer 100 inside the template guide ring 5 as shown by the dotted line in FIG. Further, during polishing, the pressurizing surface 1 is made to face the polishing pad 200 as shown by the dotted line in FIG.

In single-side polishing of a wafer using the polishing head 10 of FIG. 1, a load is applied to the flange 3 and pressure is applied to press the polishing head 10 against the polishing pad 200, and air is introduced into the wafer pressurizing section 21. As a result, the wafer 100 is pressurized via a portion of the back plate 22, fluid sealing section 23, and back pad 24. Thereby, the wafer 100 is pressed against the polishing pad 200. A portion of the flange 3, wafer pressurizing section 21, back plate 22, fluid sealing section 23, and back pad 24 communicate with the portion 1a corresponding to the inside of the inner retainer ring 4b of the pressurizing surface 1 shown in FIGS. 1 and 2. ing. That is, the portion 1a of the pressing surface 1 shown in FIGS. 1 and 2 corresponding to the inside of the inner retainer ring 4b is configured to press the wafer.

A portion of the load applied to the flange 3 is transmitted to the inner retainer ring 4b. The load transmitted to the inner retainer ring 4b is transmitted in order through the back pad 24 and the template guide ring 5, and is applied to a portion 200b of the polishing pad 200. As a result, part 200b of polishing pad 200 is deformed, and its surface is pushed down.

On the other hand, the outer retainer ring 4a can apply a load to the polishing pad 200 independently of the load applied to the flange 3, as will be explained in detail below.

The outer retainer ring pressurizing section 41 is a space, and the pressure is increased by introducing air into the space, for example. As a result, a part of the outer pressure section sealing member 42, which is an elastic body, is pushed down. The pressed down outer pressure section seal member 42 applies a load to the outer retainer ring 4a arranged below. The load applied to the outer retainer ring 4a is sequentially transmitted to a portion of the back pad 24 that is in contact with the outer retainer ring 4a, and a portion of the template guide ring 5 that is in contact with this, and is then applied to a portion 200a of the polishing pad 200. As a result, part 200a of polishing pad 200 is deformed, and its surface is pushed down.

The pressurization of the outer retainer ring pressurizer 41 is independent of the pressurization from the flange 3. Therefore, the load originating from the outer retainer ring pressurizing portion 41 and transmitted to the outer retainer ring 4a is independent of the load transmitted to the inner retainer ring 4b originating from the flange 3. Therefore, in the polishing head 10, the outer retainer ring 4a and the inner retainer ring 4b are configured to apply a load to the polishing pad 200 independently of each other.

Furthermore, since the load applied by the outer retainer ring 4a to the polishing pad 200 is independent of the load applied by the inner retainer ring 4b, it is related to the load by the inner retainer ring 4a in that it originates from the pressure applied from the flange 3. The load applied to the wafer 100 by the portion 1a of the pressurizing surface 1 is also independent.

Therefore, according to the polishing head 10 shown in FIGS. 1 and 2, it is possible to independently control and increase the load from the outer retainer ring 4a to the polishing pad 200 without causing a change in the load on the wafer in-plane 100P. I can do it. Thereby, the polishing pad 200 can be deformed and the load on the vicinity of the edge portion 100E of the wafer 100 can be reduced.

This action and effect will be explained in more detail with reference to FIG. 3. FIG. 3(a) is a schematic diagram showing a case where the conventional polishing head 10' described above with reference to FIG. 8 is used. FIG. 3(b) is a schematic diagram showing a case where the polishing head 10 according to an example of the present invention described with reference to FIGS. 1 and 2 is used.

As shown in FIG. 3(a), the conventional polishing head 10' can press down a portion of the surface of the polishing pad 200 using the retainer ring 4'. Thereby, the load applied from the polishing pad 200 to the vicinity of the edge portion 100E of the wafer 100 can be reduced. On the other hand, if the load applied by the retainer ring 4' is increased in an attempt to enhance this reduction effect, the load applied to the in-plane 100P of the wafer 100 from the polishing pad 200 will also increase, which will reduce the load at the edge. No difference occurs between the inside and outside, making it impossible to further reduce edge roll-off.

On the other hand, in the polishing head 10 of the present invention, the outer retainer ring 4a applies a load to the polishing pad 200 independently of the inner retainer ring 4b, thereby removing the load from the polishing pad 200, as shown in FIG. 3(b). A part of the surface of the polishing pad 200 can be further depressed without changing the load applied to the in-plane 100P of the wafer 100. Thereby, the load applied from the polishing pad 200 to the vicinity of the edge portion 100E of the wafer 100 can be further reduced. As a result, edge roll-off can be further reduced.

In the explanation with reference to FIGS. 1 and 2, the outer retainer ring pressurizing section 41 has been described as a pneumatic pressurizing section, but the means for applying the load to the polishing pad 200 by the outer retainer ring 4a is the inner retainer ring 4b. There is no particular limitation, and other means may also be used as long as they can be controlled independently of the load applied to the polishing pad 200.

Further, although the template guide ring 5 has an arbitrary configuration, by further providing the template guide ring 5, the wafer 100 can be held securely and the load applied to the vicinity of the edge portion 100E can be controlled with high precision.

[Wafer single-sided polishing method]
Next, an example of the method for polishing one side of a wafer according to the present invention will be explained with reference to FIG. FIG. 4 is a schematic diagram showing a method for polishing one side of a wafer according to an example of the present invention.

In the method of this example, the polishing head 10 of the present invention described with reference to FIGS. 1 and 2 is used. The wafer 100 is held at a portion 1a of the pressurizing surface 1 of the polishing head 10 that corresponds to the inside of the inner retainer ring 4b.

On the other hand, a rotating surface plate 201 is prepared. A polishing pad 200 is attached to the upward facing surface of the rotating surface plate 201. Furthermore, a rotating shaft 202 is joined to the downward facing surface of the rotating surface plate 201.

Next, the polishing head 10 holding the wafer 100 is pressed against the polishing pad 200 on the rotating surface plate 201. In addition, loads are independently applied to the polishing pad 200 by the outer retainer ring 4a and the inner retainer ring 4b of the polishing head 10, thereby deforming the polishing pad 200. More specifically, part 200a of polishing pad 200 is deformed by the load applied by outer retainer ring 4a. On the other hand, part 200b of polishing pad 200 is deformed by the load from inner retainer ring 4b.

While holding and pressurizing the wafer 100 with the polishing head 10 in this manner, the wafer 100 is polished with the deformed polishing pad 200.

During polishing, the polishing head 10 is rotated about the flange 3 as an axis. Further, the rotating surface plate 201 is rotated around the rotating shaft 202. As a result, the deformed polishing pad 200 comes into sliding contact with one side of the wafer 100 and polishes it. Further, during polishing, slurry 301 is provided from the slurry supply device 300 to the polishing surface of the polishing pad 200 .

The polishing head 10, polishing pad 200, and slurry supply device 300 can constitute a single-sided polishing device 1000.

In this way, the polishing head 10 applies pressure to the wafer 100 and presses the wafer 10 against the polishing surface of the polishing pad 200 while rotating the wafer 100 within the polishing surface of the polishing pad 200 to perform polishing. This polishing is performed using the polishing pad 200 in which a portion 200a and another portion 200b are deformed as described above. Thereby, it is possible to prevent an excessive load from being applied to the vicinity of the edge portion 100E of the wafer 100 without changing the load applied to the in-plane 100P of the wafer 100. As a result, while sufficiently polishing the in-plane 100P of the wafer 100, edge roll-off at the edge portion 100E of the wafer 100 can be reduced, and the amount of deterioration in flatness of the edge portion 100E of the wafer 100 can be reduced.

Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples, but the present invention is not limited thereto.

(Example)
Using the polishing head having the structure described with reference to FIGS. 1 and 2, the pressure at the outer retaining ring is set as the reference value 1 (100%) at the inner retaining ring, as shown in Tables 1 and 2 below. One-side polishing of the wafer was performed with the ratio of 0%, 200%, and 300% as examples. A silicon wafer with a diameter of 300 mm <100> was used as the wafer to be polished.

(Comparative example)
As a comparative example, using a polishing head with a conventional retainer ring shown in Fig. 8, one-side polishing of a wafer was performed under pressure conditions such that the load from the wafer presser when stationary and the load from the retainer ring were the same. went.

(Load distribution measurement)
Before polishing, in order to confirm that the load applied from the polishing pad to the vicinity of the edge changes due to the pressurization of the outer retainer ring, a tactile sensor (pressure distribution measurement sensor) 400 was installed in the form shown in FIG. The load distribution was measured. The results are shown in FIG.

FIG. 6 is a plot in which the horizontal axis represents the distance from the head center 10C shown in FIG. 5 (average in the angular direction), and the vertical axis represents the load that each portion of the wafer 100 receives.

As is clear from FIG. 6, in the example, when the pressure on the outer retainer ring was set to 200% and 300% of the pressure on the inner retainer ring of 100%, no load was applied on the outer retainer ring. It can be seen that the load applied near the edge of the wafer (distance from the center of the head is around 150 mm) was reduced compared to the case (0%) and the comparative example. On the other hand, it can be seen that the load on the wafer surface did not change. From this result, it was confirmed that by using the polishing head of the example, it was possible to control the load applied near the edge of the wafer independently of the load applied within the wafer surface.

(Single-sided polishing test)
In the polishing process, a polishing pad is attached to a ceramic surface plate, and while a polishing slurry of KOH-based alkaline aqueous solution containing silica-based abrasive grains is supplied to the surface plate, the polishing head and surface plate are rotated to slide the wafer onto the polishing pad. I did this by letting them touch each other.

The wafers 100 of Comparative Examples and Examples after single-sided polishing were subjected to SC1 cleaning. Regarding flatness, the wafer after cleaning was measured using Wafer Sight 2 manufactured by KLA, and as an index of the effect on the flatness of the wafer edge, the amount of change in ESFQD (Edge Site Front least sQuares Deviation) before and after polishing was calculated. Using. Single-sided polishing was performed for 10 wf under each pressure condition. The average value is shown in FIG.

The results shown in FIG. 7 show that the amount of change in ESFQDs was reduced by increasing the pressure on the outer retainer ring of the polishing head of the example. From this, it was confirmed that single-sided polishing using the polishing head of the example had the effect of reducing the amount of roll-off at the edge portion.

In addition, in single-sided polishing using the polishing head of the example, even if polishing is performed with increased pressure on the outer retainer ring, the polishing within the wafer surface is performed to the same extent as when no load is applied with the outer retainer ring. I was able to do that.

On the other hand, when the pressure at the retainer ring of the polishing head of the comparative example was increased, while the ESFQD value did not change, there was a tendency for the number of defects to increase and the roughness after polishing to increase. This is because as the pressure in the retainer ring of the polishing head in the comparative example was increased, the load applied within the wafer surface also increased, so no pressure difference occurred between the inside and outside, but the increase in external pressure caused the slurry inflow volume to increase. This is presumed to be due to a decline in

Note that the present invention is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any embodiment that has substantially the same configuration as the technical idea stated in the claims of the present invention and has similar effects is the present invention. covered within the technical scope of.

DESCRIPTION OF SYMBOLS 1...Pressure surface, 1a...Part of pressure surface, 2...Upper metal, 2a...Protrusion, 3...Flange, 4 and 4'...Retainer ring, 4a...Outer retainer ring, 4b...Inner retainer ring, 5...Template Guide ring, 10 and 10'...polishing head, 10C...head center, 20...upper metal sealing member, 21...wafer pressure section, 22...back plate, 22a...back plate stopper, 23...fluid sealing section, 24...back Pad, 41...Outer retaining ring pressure section, 41'...Retainer ring pressure section, 42...Outer pressure section sealing member, 100...Wafer, 100E...Edge section, 100P...Inside wafer surface, 200...Polishing pad, 200a , 200b and 200c...part of the polishing pad, 201...rotating surface plate, 202...rotating shaft, 300...slurry supply device, 301...slurry, 400...tactile sensor, 1000...single side polishing device.

Claims (2)

A polishing head configured to hold a wafer, apply pressure to the wafer, press the wafer against a polishing surface of a polishing pad, and rotate the wafer within the polishing surface to perform polishing,
has a pressure surface;
A retainer ring is provided on the outer periphery of the pressure surface side,
The retainer ring includes an outer retainer ring and an inner retainer ring located inside the outer retainer ring,
A portion of the pressing surface corresponding to the inside of the inner retainer ring is configured to press the wafer,
The outer retainer ring and the inner retainer ring are configured to apply a load to the polishing pad independently of each other,
a template guide ring configured to receive loads from the outer retainer ring and the inner retainer ring and transmit the loads to the polishing pad;
included in a portion disposed between the retainer ring and the template guide ring and a portion of the pressurizing surface of the polishing head corresponding to the inner side of the inner retainer ring, and is disposed so as to pressurize the wafer. 1. A polishing head, further comprising a back pad having a flat portion . A method for polishing one side of a wafer,
Using the polishing head according to claim 1, holding a wafer on the portion of the pressurizing surface that corresponds to the inside of the inner retainer ring,
Applying a load to the polishing pad independently by the outer retainer ring and the inner retainer ring to deform the polishing pad,
A method for polishing one side of a wafer, comprising polishing the wafer with the deformed polishing pad while holding and pressurizing the wafer with the polishing head.

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