JP2020040188A - Retainer ring, polishing head having the same, and polishing device - Google Patents

Abstract

To provide a retainer ring for inhibiting vibrations in a polishing amount between a wafer end part and the other part.SOLUTION: A retainer ring includes: an annular body 41 having a first portion 41a connected to a retainer ring cover 40 and a second portion 41b which is held by the first portion and configured so that a surface which contacts with a surface of a polishing pad can swing with a held portion set to a supporting point; and an airbag 52 and a pressing ring 42 which apply pressure to the second portion to press the polishing pad.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a retainer ring used for polishing a substrate such as a semiconductor wafer or a glass substrate, a polishing head having the same, and a polishing apparatus.

  2. Description of the Related Art In recent years, in a manufacturing process of a semiconductor device, a flattening technique of a substrate surface has become more and more important with a high integration of a substrate (hereinafter, referred to as a wafer) such as a semiconductor wafer or a glass substrate. The most important of these planarization techniques is chemical mechanical polishing (CMP). In this chemical mechanical polishing, a substrate is polished while a polishing liquid containing abrasive grains such as silica (SiO2) is supplied onto a polishing surface such as a polishing pad using a polishing apparatus (also called a polishing apparatus). The surface is slid and polished.

  In addition, the polishing head holding the wafer is formed in a ring shape so as to surround the outer periphery of the wafer in order to prevent the wafer urged by the sliding friction force due to rotation in the polishing process from flying outward. Provided retaining ring. In this retainer ring, the lower end surface thereof comes into contact with the polishing pad, and the wafer being polished is received by its inner peripheral surface, thereby restricting the wafer from jumping out.

Further, the surface pressure of the retainer ring has a great influence on the surface pressure control of the edge portion of the wafer.
For example, when there is no retainer ring, when the wafer is pressed against the polishing pad, the polishing pad is elastically deformed and compressed. At this time, a different compressive stress acts on the edge of the wafer at the boundary portion between the compressed portion and the uncompressed portion as a material mechanical behavior at the boundary region between the compressed portion and the uncompressed portion, and the polishing amount is larger than at other portions. May be too small.

For example, in the polishing apparatuses disclosed in Patent Literatures 1 and 2, at least the inner peripheral portion of the retainer ring is formed of an elastic body such as rubber, so that the contact range between the wafer and the retainer ring is increased to reduce the wafer rotation speed. It is possible to increase the speed.
Further, in the polishing apparatus disclosed in Patent Document 2, the inner peripheral surface of the retainer ring is elastically deformed toward the outer periphery when receiving the frictional force of the wafer, so that the contact range between the wafer end portion and the inner peripheral surface of the retainer ring is reduced. In other words, local deformation of the wafer is suppressed.

JP 2010-40604 A JP 2017-209775 A

In such a polishing apparatus, the relative speed and pressing force between the surface of the wafer to be polished (hereinafter referred to as the “surface to be polished”) and the polishing pad are set over the entire surface to be polished. If it is not uniform, polishing unevenness such as insufficient polishing or overpolishing will occur. In the following, the case of being insufficient or too short may be referred to as too little or too little.
For example, ROA (Roll Off Amount: also referred to as a roll-off amount and an edge roll-off amount) and ESFQR (Edge Site Flont least sQuare) are used as evaluation indexes (flatness evaluation indexes) for evaluating flatness near a wafer edge (edge). Range). ROA and ESFQR are parameters indicating the accuracy of the outer peripheral surface of the wafer.
In recent years, a flat shape has been demanded up to the outer periphery of the wafer, and a polishing apparatus capable of performing polishing with high flatness of 10 [nm] or less according to these flatness evaluation indexes has been required.

  However, in the method of increasing the contact range between the wafer end and the inner periphery of the retainer ring and suppressing local deformation of the wafer as in Patent Documents 1 and 2, it is possible to sufficiently improve SFQR and the like in a specific portion on the polished surface. The challenge remains. In addition, there remains a problem that the polishing amount per unit time at the wafer edge becomes uneven and ESFQR deteriorates.

  SUMMARY OF THE INVENTION It is a main object of the present invention to provide a retainer ring for suppressing a variation in a polishing amount between a wafer end portion and another portion. Further, a polishing apparatus and a constituent device thereof are provided.

  The present invention for solving the above problems has a polishing head that holds a substrate to be polished so that a surface to be polished is in sliding contact with the polishing pad. A retainer ring for restricting protrusion of the polishing pad, wherein the retainer ring is held at the first portion connected to the polishing head and at the first portion, and the surface of the polishing pad is supported by the holding portion as a fulcrum. An annular body having a second portion having a surface that is configured to be able to swing, and a first portion that applies pressure to a second portion of the annular body and presses the surface of the polishing pad. And pressing means.

  Further, the polishing head of the present invention is a polishing head provided in a polishing apparatus having a horizontally rotating polishing pad, wherein a substrate to be polished is polished so that a surface to be polished is in sliding contact with the polishing pad. Holding means, a retainer ring formed in a shape surrounding the outer periphery of the holding means holding the substrate, and a driving means for horizontally rotating the holding means, wherein the retainer ring is A first portion connected to the holding means, and a second portion held by the first portion, the surface of which is in contact with the surface of the polishing pad with the holding portion serving as a fulcrum. And a first pressing means for applying pressure to a second portion of the annular body to press the polishing pad.

  The polishing apparatus of the present invention is a polishing apparatus having a polishing table having a polishing pad, and a polishing head for holding a substrate to be polished and bringing a surface to be polished into sliding contact with the polishing pad. The polishing head has a holding means for holding a substrate to be polished so that a surface to be polished is in sliding contact with the polishing pad, and a shape surrounding the outer periphery of the holding means in a state of holding the substrate. And a driving means for horizontally rotating the holding means, wherein the retainer ring is held by a first part connected to the holding means, and held by the first part. An annular body having a second portion whose surface in contact with the surface of the polishing pad is swingable with the holding portion as a fulcrum; and applying pressure to the second portion of the annular body. Then polishing And having a first pressing means for pressing the head, the.

  ADVANTAGE OF THE INVENTION According to this invention, the retainer ring for suppressing the dispersion | variation of the polishing process amount of a wafer edge part and another part can be provided. In addition, it is possible to prevent the occurrence of uneven polishing such as partial insufficient polishing or overpolishing of the surface to be polished of the substrate, and to further improve the ESFQR and the like of the substrate surface.

FIG. 2 is a schematic longitudinal sectional view for explaining an example of a polishing head and a peripheral configuration of the polishing head of the polishing apparatus according to the embodiment. FIG. 3 is a diagram for explaining an example of a configuration of a polishing head. The figure for explaining an example of the composition of the retainer ring (retainer mechanism). (A), (b) is a schematic diagram for demonstrating the pressing of the polishing pad surface by the conventional retainer ring. (A), (b) is a schematic diagram for demonstrating the pressing of the polishing pad surface by a retainer ring in the case where the edge part of a wafer does not contact the inner wall of the retainer ring during polishing. 9 is a flowchart for explaining an example of a main control procedure performed by a control unit when performing polishing.

[Example of Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the polishing apparatus of the present embodiment targets a substrate such as a semiconductor wafer or a glass substrate (hereinafter, also referred to as a wafer) as a polishing target. In this specification, one surface of the substrate is referred to as a circular or substantially circular surface to be polished. The surface of the polishing pad that contacts the surface to be polished of the wafer is referred to as a polishing surface.

The polishing apparatus has a polishing table to which a polishing pad serving as a polishing member is bonded, a polishing table for horizontally rotating the polishing pad, and a polishing head for slidingly contacting the surface to be polished of the substrate with the polishing pad. Have.
The substrate is pressed against the polishing pad by the polishing head. Then, the polishing process is performed on the surface to be polished by rotating the polishing table and the polishing head while supplying the polishing liquid (slurry) to the polishing pad.

FIG. 1 is a schematic configuration diagram of a polishing apparatus 100 according to the present embodiment.
The polishing apparatus 100 shown in FIG. 1 has a polishing table 11, and a polishing pad 12 is adhered to a surface of the polishing table 11.
The polishing apparatus 100 further includes a polishing head 13 for holding a substrate (wafer) W and pressing a surface to be polished against the polishing pad 12, a nozzle N for supplying a polishing liquid toward the polishing pad 12, and a polishing table 11. And a motor (not shown) for rotating the polishing head 13 horizontally, a polishing liquid supply mechanism (not shown) connected to the nozzle N, and a computer for controlling each drive unit including the motor. It has a control unit 20.

  The polishing pad 12 has a disk shape, and its radius is larger than the maximum diameter (diameter) of the surface to be polished of the wafer W. In this mechanism, the number of rotations and the direction of rotation of the polishing pad 12 and the polishing head 13 are changed to adjust the relative polishing speed in the plane of the wafer W. The polishing pad 12 itself has elasticity, and may be made of a commercially available material such as a nonwoven fabric or a foamed urethane.

  The polishing head 13 has a holding mechanism for holding the wafer W so that the surface to be polished is in sliding contact with the polishing pad 12, and the direction of the polishing pad 12 from the back side (back side) of the surface to be polished to the held wafer W. It has a pressing mechanism for applying pressure toward. Details of these mechanisms will be described later.

The control unit 20 controls the positioning of the nozzle N, the control to start or stop the supply of the polishing liquid from the nozzle N, the control of the supply amount of the polishing liquid ejected and supplied from the nozzle N per unit time, the start and stop control of the motor, and the like. Mainly. The rotational force of the motor controlled by the control unit 20 is transmitted to the polishing table 11 via a drive unit (not shown). As a result, the polishing table 11 rotates horizontally or stops rotating.
The rotational force (torque) of the motor is also transmitted to the polishing head 13 via a drive unit (for example, a universal joint) not shown. As a result, the polishing head 13 rotates horizontally or stops rotating.

The rotation direction of the polishing table 11 and the rotation direction of the polishing head 13 are generally the same. This is because if the direction is reversed, the relative polishing speed in the wafer surface becomes non-uniform, and there is a possibility that the uniform polishing is impossible. By setting the rotation direction of the polishing table 11 and the rotation direction of the polishing head 13 to be the same direction and adjusting the rotation speed of both, polishing accuracy can be improved.
The rotational force of a single motor may be transmitted to the polishing table 11 and the polishing head 13 via gears having different gear ratios, or the rotational force may be transmitted through individual motors. good. Both can be arbitrarily designed. The control procedure by the control unit 20 will be described later.

The polishing liquid is supplied from the nozzle N to the polishing pad 12 for a predetermined time while the rotation speed of the polishing table 11 has reached a predetermined value under the control of the control unit 20.
Next, the polishing head 13 included in the polishing apparatus 100 and its peripheral configuration will be described in detail.

[Polishing head and its peripheral configuration]
FIG. 2 is a schematic longitudinal sectional view for explaining an example of the polishing head 13 included in the polishing apparatus 100 and its peripheral configuration. An example of the configuration of the polishing head 13 will be described with reference to FIG.
In the following description, the wafer W is held such that the surface to be polished is in sliding contact with the polishing pad 12 at a pressure controlled by the polishing apparatus 100 in order to further improve the GBIR and the like of the wafer surface. The pressure applied to the polished wafer W from the back side (back side) of the surface to be polished toward the polishing pad 12 is referred to as pressure P1.
Further, the pressure applied to the annular body 41 included in the configuration of the retainer ring (retainer mechanism) according to the present embodiment by an airbag 51 described later is referred to as pressure P2. The pressure applied to the annular body 41 via the press ring 42 by the airbag 52 described later is referred to as pressure P3.

[Configuration of polishing head]
The polishing head 13 shown in FIG. 2 is roughly divided into a holding mechanism for applying a polishing pressure (processing pressure) to the wafer W to be polished and bringing the wafer into sliding contact with the polishing pad 12, and a polishing pressure (processing pressure). And a pressing mechanism for pressing the annular body 41 toward the polishing pad 12 side. Note that the annular body 41 included in the configuration of the retainer ring (retainer mechanism) according to the present embodiment restricts the wafer W urged by the rotational force of the polishing head 13 and the polishing table 11 from projecting in the outer peripheral direction.

The holding mechanism of the polishing head 13 functions as a holding unit, and is a mechanism for applying a polishing pressure (pressure P1) to the wafer W to be polished and bringing the wafer W into sliding contact with the polishing pad 12 as described above.
The pressing mechanism of the polishing head 13 functions as pressing means, and the first pressure mechanism (P1a) for adjusting the pressure P1, the second pressure mechanism (P2a) for adjusting the pressure P2, and the second pressure mechanism for adjusting the pressure P3. 3 pressure mechanism (P3a).

The polishing head 13 includes a head cover 30 having a head drive shaft, a retainer ring cover 40 (sometimes called a vessel 40), a rubber membrane 31, a membrane holder ring 32, and a backing film T.
The retainer ring cover 40 is formed in a double cylindrical body (a casing formed in an annular shape) having an upper bottom surface. Further, each component of the retainer ring according to the present embodiment is accommodated in a space formed by the inner wall and the outer wall of the retainer ring cover 40. Specifically, as shown in FIG. 2, the annular body 41, the pressing ring 42, the airbag 52 (second pressing means) for pressing the annular body 41 in the direction of the polishing pad 12, the pressing ring 42 An airbag 51 (first pressing means) or the like that applies pressure to a part of the annular body 41 by pressing the airbag in the direction of the polishing pad 12 is provided.

The rubber membrane 31 is an elastic cylindrical body formed in a substantially cylindrical shape (pan-shaped) with an inner diameter size that can be fitted on the inner peripheral surface of the retainer ring cover 40. The rubber membrane 31 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicone rubber.
The rubber membrane 31 has its outer peripheral surface adhered to the inner peripheral surface of the retaining ring cover 40 via a sealing mechanism, and is thereby held by the retaining ring cover 40.

  The backing film T is a film-like thin film stretched on the outer bottom surface of the rubber membrane 31. For example, a porous material such as a nonwoven fabric can be used as the material. The backing film T holds the surface to be polished of the wafer W facing (abutting) the polishing pad 12 so that the center axis of the wafer W and the rotation axis of the wafer W substantially coincide with each other in a state of sliding contact.

  The polishing head 13 according to the present embodiment is configured such that the end of the wafer W does not contact the inner wall of the opposed annular body 41 during polishing, that is, the polishing head 13 is in a non-contact state. Specifically, it is realized by, for example, vacuum suction between the backing film T and the wafer W.

  For example, the polishing head 13 is capable of sucking a gas (for example, air) or the like interposed between the backing film T and the wafer W (contact surface) via an air pipe (not shown) connected to a fluid supply mechanism (not shown). Be composed. That is, a predetermined suction force is applied to the back side of the wafer W. Thereby, it is possible to adjust the frictional force generated between the backing film T and the wafer W, that is, on the back side of the wafer W via the control unit 20. This makes it possible to realize Gap = constant in Gap described later.

  In the polishing head 13, as shown in FIG. 2, a rubber membrane 31 is mounted on the inner peripheral surface of the retainer ring cover 40 in a space formed by the head cover 30 and the retainer ring cover 40. As a result, a pressure chamber (sealed internal space) for applying pressure to the wafer W from the back side (back side) of the surface to be polished toward the polishing pad 12 is formed. The head cover 30, the retaining ring cover 40, the rubber membrane 31, and the backing film T function as a holding mechanism.

  Further, the membrane holder ring 32 is formed using a SUS material or the like, and is provided on the inner peripheral side of the rubber membrane 31. The membrane holder ring 32 presses the peripheral surface of the rubber membrane 31 toward the inner peripheral surface side of the retainer ring cover 40 to bring the rubber membrane 31 into close contact.

The polishing head 13 included in the polishing apparatus 100 supplies or supplies a pressurized fluid (for example, compressed air) to each of the pressure chambers and the airbags 51 and 52 via an air pipe connected to a fluid supply mechanism (not shown). Is configured to be able to collect the pressurized fluid.
The polishing head 13 is configured to generate a processing pressure or the like applied to the wafer W in accordance with the amount of the pressure fluid supplied through the pressure chamber. In addition, when the pressure fluid is sealed in the airbags 51 and 52 and inflated, the annular body 41 presses the polishing pad 12 with pressures P2 and P3 according to the amount of the sealed pressure fluid.
Further, control such as supply of a pressure fluid for generating the pressures P1 to P3 or recovery of the supplied pressure fluid is performed by the control unit 20 via a fluid supply mechanism. In this way, the polishing pressure and the like during the polishing process are controlled. Note that the airbags 51 and 52 are examples of a pressing unit, and the pressing unit according to the present invention is not limited to this configuration.

In addition, for example, by sucking the gas in the internal space, the internal space is made negative pressure. Accordingly, the rubber membrane 31 is deformed into a concave shape, and at the same time, the wafer W is also deformed by suction. In this case, a stopper for stopping deformation is required.
Further, when the pressurized fluid is supplied via the above-described fluid supply mechanism, the convex deformation of the rubber membrane 31 occurs. Since a gap is formed between the bent rubber membrane 31 and the rear surface of the wafer W, the holding state of the wafer W held by the polishing head 13 can be smoothly released.

  The head cover 30 is connected to a drive mechanism (not shown) for driving the polishing head 13 to rotate. The rotational driving force transmitted to the head cover 30 is transmitted to the annular body 41, the rubber membrane 31, and the backing film T via the retainer ring cover 40. Thus, the polishing head 13 rotates.

[Pressing mechanism]
The pressing mechanism of the polishing head 13 presses the annular body 41 toward the polishing pad 12 as described above.
The retainer ring cover 40 is a space in which an inner annular portion surrounding the outer periphery of the rubber membrane 31 and the like holding the wafer W, an annular body 41 formed by inner and outer walls thereof, a push ring 42, and the like are provided. And a part. The annular body 41, the press ring 42, and the like rotate integrally by the rotational driving force transmitted to the retainer ring cover 40 via the head cover 30.

FIG. 3 is a diagram for explaining an example of the configuration of the retainer ring according to the present embodiment.
As described above, the retainer ring (retainer mechanism) according to the present embodiment is configured to include the annular body 41, the push ring 42, and the airbags 51 and 52.
As shown in FIG. 3, the annular body 41 is an annular body formed in a substantially Σ shape, and has a first portion 41 a in contact with the inner wall of the retainer ring cover 40 and a surface (bottom surface sliding) in contact with the surface of the polishing pad 12. (Which may be referred to as a moving part). The second portion 41b of the annular body 41 is configured to be able to swing to a position indicated by a substantially broken line with the intersection O (A side) of the dashed line shown in FIG.
As shown in FIG. 3, the pressing ring 42 is an annular member formed in an inverted L-shape, and has a portion in contact with the airbag 52 and a portion near the outer end (B side) of the second portion 41 b. And a portion to be pressed.

The annular body 41 is provided with a pad pressing force (pressure P2) corresponding to the amount of the pressurized fluid sealed in the airbag 51. Thus, the ring member 41 can be raised or lowered, and the polishing pad 12 can be pressed by the second portion 41b of the ring member 41.
The pressing ring 42 is provided with a pad pressing force (pressure P3) corresponding to the amount of the pressurized fluid sealed in the airbag 52. As a result, the lifting or lowering operation of the push ring 42 becomes possible, and the vicinity of the outer end of the second portion 41b of the annular body 41 (side B) is relatively higher than the vicinity of the inclusion side (side A). The polishing pad 12 can be pressed with pressure.

  As described above, when the polishing pad 12 is pressed by the second portion 41b of the annular body 41, the pressure near the outer end of the second portion 41b (side B) is higher than that near the inner side (side A). Higher control becomes possible. In other words, the push ring 42 applies pressure to a predetermined location on the second portion 41b that is a predetermined distance away from the location where the first portion 41a of the annular body 41 holds the second portion 41b. Will be configured. That is, it is possible to form a gradient pressure on the polishing pad 12.

  As described above, the polishing head 13 is configured such that the end of the wafer W does not abut on the inner peripheral side inner wall of the annular body 41 during polishing. Therefore, it is possible to smoothly apply the pressure to the annular body 41 and to perform “pressing down the pad” by pressing the surface of the polishing pad 12 by the annular body 41 with high functional accuracy.

  As described above, the pressing mechanism of the polishing head 13 of the polishing apparatus 100 according to the present embodiment applies polishing pressure to the wafer W to be polished to bring the wafer W into sliding contact with the polishing pad 12, The pressing of the surface of the polishing pad 12 by the annular body 41 is controlled to function as a mechanism for reducing the ESFQR at the edge of the wafer W.

  FIG. 4 is a schematic view for explaining the pressing of the polishing pad surface by the conventional retainer ring. FIG. 5 is a schematic diagram for explaining the pressing of the polishing pad surface by the retainer ring when the end of the wafer W is configured not to contact the inner wall of the retainer ring during the polishing process.

  FIG. 4A shows an example of the surface state of the polishing pad when no pressure is applied to the retainer ring. As shown in FIG. 4A, the polishing pressure applied to the wafer W during the polishing process is a pressure P1, and the pad displacement (elastic displacement) is δ1. In this case, when the wafer is pressed against the polishing pad, the polishing pad is compressed by the pad displacement δ1 (see Y1 in the figure). At this time, a large compressive stress is generated at the edge portion of the wafer in the process of compressing the polishing pad (Boussinesq @ s Stress), and an event that the polishing amount is larger than that of other portions is reported in an academic journal or the like.

FIG. 4B shows that the polishing pressure applied to the wafer W during the polishing process is a pressure P1 and a pad displacement δ1, and the polishing pressure applied to the retainer ring is a pressure P2 and a pad displacement δ2. An example of the surface state of the polishing pad when the end portion contacts the inner wall surface of the retainer ring is shown.
The wafer receives a horizontal rubbing force in the tangential direction of the radius of the platen due to the rotation of the platen, and the gap (GAP) becomes 0 (zero) at the contact portion between the wafer end and the inner wall of the retainer during polishing.

In this case, the stress at the edge of the wafer can be analyzed using the values of the pressure P1, the gap, and the pressure P2, and is referred to as Boussinesq's Stress. Generally, when the polishing amount at the wafer edge under the condition of Gap = 0 is compared with the central portion, it tends to be smaller at P2> P1 than at the central portion and larger at P2 <P1.
The stress at the edge of the wafer can be analyzed based on the values of “P1, Gap, P2” and is called Edge Stress (corresponding to Hertz stress). Generally, when the polishing amount at the edge of the wafer under Gap = 0 is compared with that at the center, the polishing amount tends to be smaller at P2> P1 and larger at P2 <P1.

FIG. 5A shows that the polishing pressure applied to the wafer W during the polishing process is the pressure P1, the polishing pressure applied to the retainer ring is the pressure P2, and the polishing pressure is about 1 mm between the wafer end and the retainer. An example of a surface state of the polishing pad when a gap (GAP) of [mm] is opened (a 180-degree facing portion based on a point of Gap = 0) is shown.
When the wafer is set in this manner, the wafer is subjected to a horizontal rubbing force in the tangential direction of the radius of the platen due to the rotation of the platen, and the gap between the retainer and the wafer end at an arbitrary point at the wafer end during polishing. May change continuously within a range of, for example, 0 to the maximum GAP value during one rotation. When the gap changes in the same P2 state as described above, the stress distribution at the edge of the wafer shows a complicated behavior during one rotation, which is a main factor that causes a variation in processing accuracy.

  FIG. 5B schematically shows the configuration of the annular body 41 according to the present embodiment. 4 (a), (b), and the general-purpose polishing machine shown in FIG. 5 (a), when configured as shown in FIG. 5 (b), by adjusting the pressures P2 and P3, respectively. An inclination angle θ [degree] can be generated in the bottom sliding portion of the second portion 41 b of the annular body 41. Therefore, the surface deformation of the polishing pad at the edge of the wafer can be controlled by a method different from the conventional method, and the distribution of the polishing pressure at the simultaneous edge can also be controlled. It can be formed stably (see Y4 in the figure).

As described above, when there is no section L as shown in FIG. 5A, “P1, Gap, P2” in which excessive or insufficient polishing does not occur at the wafer edge is a limited value in a narrow specific range, and is relatively limited. It can be said that it is weak against Gap fluctuation.
Also, when there is a section L as shown in FIG. 5B, if the L section is formed by the pad displacement amount δ2 and the inclination angle θ, excessive or insufficient polishing does not occur at the wafer end “P1, Gap, P2”. Can be said to be relatively resistant to Gap fluctuation.

  As described above, the pad pressing force (retainer pressure) by which the retainer presses down the pad is controlled in order to alleviate the excessive / small stress generated at the edge of the wafer. This makes it possible to minimize excessive / small stress and improve uniform polishing in polishing.

[Control procedure for polishing]
Next, a polishing procedure by the polishing apparatus 100 of the present embodiment will be described. FIG. 6 is a flowchart illustrating an example of a main control procedure performed by the control unit 20 when performing the polishing process.
The control unit 20 starts the control when the operator of the polishing apparatus 100 receives an input of a start instruction (S100). After the predetermined initial processing, the holding mechanism of the polishing head 13 starts holding the wafer W (S101).

The control unit 20 holds the wafer W from a wafer delivery table (not shown) and moves the polishing head 13 to a polishing start position (S102).
The control unit 20 supplies a predetermined amount of pressure fluid to generate pressures P1 and P3 (S103). Thereby, a predetermined pressure is applied to the wafer W via the rubber membrane 31 and to each of the surfaces of the polishing pad 12 via the annular body 41.

  The control unit 20 also checks whether an appropriate pressure is applied to the wafer W or the like through a sensor unit (not shown). When the controller 20 confirms that the pressures P1, P2, and P3 are appropriate (S104: Yes), the controller 20 issues an instruction to a motor (not shown) to start the rotation of the polishing table 11 and the polishing head 13. It is issued (S105). Thus, the polishing table 11 and the polishing head 13 start rotating horizontally.

  After instructing the rotation start of the polishing table 11 and the polishing head 13, the control unit 20 instructs the positioning of the nozzle N and also instructs the polishing liquid supply mechanism to start the supply of the polishing liquid (S106). ). Thereby, the polishing liquid is supplied from the nozzle N toward the surface of the polishing pad 12. In this way, the control unit 20 starts polishing (S107).

The control unit 20 starts adjusting each of the pressures P2 and P3 (S108). For example, by comparing the measurement result of the wafer thickness in the latest same processing time via a sensor (not shown) with the measurement result of the wafer thickness in the current same processing time, the polishing amount per time in the detection of one cycle is obtained. A correction value (P2, P3, inclination angle θ) based on the correction value is determined.
The adjustment of each of the pressures P2 and P3 may be configured such that a correction value is determined based on the measurement result of the wafer thickness after one polishing process, for example, and is reflected in the next polishing process.

The control unit 20 determines whether the polishing has been completed (S109). In this determination, for example, when it is determined that the wafer W has been polished to a desired thickness based on the detection result of the sensor, the polishing is terminated. If not (S109: No), the process returns to step S108.
When determining that the polishing is completed (S109: Yes), the control unit 20 instructs the polishing liquid supply mechanism to stop supplying the polishing liquid (S110).

  Then, the control unit 20 issues a stop instruction to the motor to stop the rotation of the polishing table 11 and the polishing head 13 (S111). Thereafter, the polishing head 13 is moved to a table on which the polished wafer W is placed (S112). Thus, a series of polishing processing ends.

  It should be noted that the determination as to whether or not the holding has been released may be configured to be detected using, for example, various sensors (not shown). After the rotation of the polishing table 11 and the polishing head 13 is stopped, the supplied pressure fluid may be collected. By performing such control, it is possible to prevent the polished wafer W from unintentionally falling off during the transfer.

  The retainer ring (retainer mechanism) according to the present embodiment, the polishing head 13 having the same, and the polishing apparatus 100 are configured such that pressing of the polishing pad 12 on the pad surface can be controlled by the pressing mechanism, and the wafer edge can be controlled. The range of stress concentration can be reduced. Thereby, it is possible to prevent the occurrence of uneven polishing such as partial insufficient polishing or overpolishing of the surface to be polished of the wafer. Further, GBIR, SFQR and ESFQR on the wafer surface can be further improved.

  In addition, a communication hole (for example, a slit formed radially) may be formed in the second portion 41 b of the annular body 41. In this case, it is possible to more precisely control the pressing of the second portion 41b by the pressing ring 42.

  The embodiments described above are for describing the present invention more specifically, and the scope of the present invention is not limited to these examples.

11 polishing table, 12 polishing pad, 13 polishing head, 20 control unit, 30 head cover, 31 rubber membrane, 32 membrane holder ring, 41 ··· Annular body, ····························································································· W: Wafer.

Claims (9)

A polishing head for holding a substrate to be polished so that a surface to be polished is in sliding contact with the polishing pad, and a retainer ring for restricting the substrate from projecting outward during the polishing. hand,
The retainer ring,
A first portion connected to the polishing head, and a second portion held by the first portion, the surface of which is in contact with the surface of the polishing pad with the holding portion as a fulcrum, which is configured to be swingable. A ring having:
And a first pressing unit that applies pressure to a second portion of the annular body to press the surface of the polishing pad.
Retaining ring. The polishing head, disposed on the outer periphery of the polishing head, having a double cylindrical body having an upper bottom surface,
The first portion of the annular body is connected to an outer periphery of an inner wall of the double tubular body,
The retainer ring according to claim 1. The first pressing means is configured to apply pressure to a predetermined location separated by a predetermined distance from a location where the first location holds the second location,
The retainer ring according to claim 1. A second pressing means for applying pressure to the first portion of the annular body so that the second portion presses the surface of the polishing pad via the first portion. And
The retainer ring according to claim 1, 2 or 3. Control means for controlling a pressure applied by the first pressing means to control an inclination angle of the second portion with respect to a surface of the polishing pad to be a predetermined angle. And
The retainer ring according to claim 1. The control means controls the pressure applied by the second pressing means,
The retainer ring according to claim 5. A polishing head provided in a polishing apparatus having a horizontally rotating polishing pad,
Holding means for holding the substrate to be polished, so that the surface to be polished is in sliding contact with the polishing pad;
A retainer ring formed in a shape surrounding the outer periphery of the holding unit holding the substrate,
Driving means for rotating the holding means horizontally,
The retainer ring is configured such that a first portion connected to the holding means and a surface that is held by the first portion and that contacts a surface of the polishing pad with the held portion as a fulcrum are swingable. And a first pressing means for applying pressure to the second portion of the annular body to press the polishing pad.
Polishing head. The retainer ring is formed in a size such that an end of the substrate held by the holding unit and an inner periphery of the retainer ring are in a non-contact state.
The polishing head according to claim 6. A polishing table having a polishing pad, a polishing head having a polishing head that holds a substrate to be polished and slidably contacts a surface to be polished to the polishing pad,
The polishing head,
Holding means for holding a substrate to be polished, so that the surface to be polished is in sliding contact with the polishing pad;
A retainer ring formed in a shape surrounding the outer periphery of the holding unit holding the substrate,
Driving means for rotating the holding means horizontally,
The retainer ring is configured such that a first portion connected to the holding means and a surface that is held by the first portion and that contacts a surface of the polishing pad with the held portion as a fulcrum are swingable. And a first pressing means for applying pressure to the second portion of the annular body to press the polishing pad.
Polishing equipment.

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