COVER ASSEMBLY, CLEANING METHOD, AND METHOD FOR MANUFACTURING COVER ASSEMBLY

Abstract

A cover assembly includes a cover cleaning part covering at least a portion of an outer peripheral surface of a rotating body. The cover cleaning part includes: an outer cover part, constituting an outer surface of the cover cleaning part; an inner cover part, constituting at least a portion of an inner surface of the cover cleaning part; a fluid chamber, formed between the outer cover part and the inner cover part; and a cleaning liquid supply port, provided in the outer cover part or the inner cover part, communicating with the fluid chamber, and for supplying a cleaning liquid to the fluid chamber. The inner cover part includes at least one cleaning liquid discharge port communicating with the fluid chamber and facing the outer peripheral surface of the rotating body.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Japan Application No. 2023-041579, filed on Mar. 16, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The disclosure relates to a cover assembly for cleaning a rotating body used in a polishing apparatus that polishes a substrate such as a wafer. The disclosure also relates to a cleaning method for cleaning a rotating body using such a cover assembly, and a method for manufacturing a cover assembly.

Related Art

Chemical mechanical polishing (CMP) is a technology for polishing a surface of a substrate such as a wafer by a chemical action of a polishing liquid and a mechanical action of abrasive grains contained in a polishing liquid and/or a polishing pad. A polishing apparatus for performing CMP generally includes: a polishing table, supporting a polishing pad; a polishing head, pressing the substrate against the polishing pad; and a polishing liquid supply nozzle, supplying a polishing liquid (slurry) to the polishing pad.

The substrate is pressed against a polishing surface of the polishing pad by the polishing head, and the polishing table and the polishing head are rotated in this state. The substrate is brought into sliding contact with the polishing surface of the polishing pad in the presence of the polishing liquid, thereby polishing a surface of the substrate. When the surface of the substrate is polished while the polishing liquid is being supplied, the polishing liquid may adhere to the polishing head. Accordingly, in order to prevent the polishing liquid from adhering to the polishing head, a cover is attached to the polishing head.

• • Patent Document 1: Japanese Patent Laid-open No. 2014-147990

However, a slight gap is present between the polishing head and the cover that covers the polishing head, and the polishing liquid may adhere to an outer peripheral surface of the polishing head and an inner peripheral surface of the cover through this gap. The polishing liquid adhering to the outer peripheral surface of the polishing head and the inner peripheral surface of the cover may dry, solidify and form particles which may fall onto the polishing surface of the polishing pad. Such particles originating from the polishing liquid cause scratches on the surface of the substrate.

SUMMARY

In one aspect, provided is a cover assembly for cleaning a rotating body used in a polishing apparatus. The cover assembly includes a cover cleaning part that covers at least a portion of an outer peripheral surface of the rotating body. The cover cleaning part includes: an outer cover part, constituting an outer surface of the cover cleaning part; an inner cover part, constituting at least a portion of an inner surface of the cover cleaning part; a fluid chamber, formed between the outer cover part and the inner cover part; and a cleaning liquid supply port, provided in the outer cover part or the inner cover part, communicating with the fluid chamber, and for supplying a cleaning liquid to the fluid chamber. The inner cover part includes at least one cleaning liquid discharge port communicating with the fluid chamber and facing the outer peripheral surface of the rotating body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating one embodiment of a polishing apparatus.

FIG. 2 is a perspective view illustrating one embodiment of a cover assembly.

FIG. 3 is a perspective view illustrating one embodiment of a first cover cleaning part.

FIG. 4 illustrates an inner surface of the first cover cleaning part illustrated in FIG. 3.

FIG. 5 is a cross-sectional view taken on line A-A in FIG. 4.

FIG. 6 is a cross-sectional view taken on line B-B in FIG. 4.

FIG. 7 illustrates a state in which a cover cleaning part cleans an outer peripheral surface of a polishing head and an inner peripheral surface of a cover assembly.

FIG. 8 illustrates one embodiment of a vacuum forming method for molding an outer cover part.

FIG. 9 illustrates an example in which a cover assembly is applied to a dressing head.

DESCRIPTION OF THE EMBODIMENTS

The disclosure provides a cover assembly that is able to prevent a polishing liquid from adhering to a rotating body such as a polishing head. Furthermore, the disclosure provides a cleaning method for cleaning a rotating body using such a cover assembly, and a method for manufacturing a cover assembly.

In one aspect, provided is a cover assembly for cleaning a rotating body used in a polishing apparatus. The cover assembly includes a cover cleaning part that covers at least a portion of an outer peripheral surface of the rotating body. The cover cleaning part includes: an outer cover part, constituting an outer surface of the cover cleaning part; an inner cover part, constituting at least a portion of an inner surface of the cover cleaning part; a fluid chamber, formed between the outer cover part and the inner cover part; and a cleaning liquid supply port, provided in the outer cover part or the inner cover part, communicating with the fluid chamber, and for supplying a cleaning liquid to the fluid chamber. The inner cover part includes at least one cleaning liquid discharge port communicating with the fluid chamber and facing the outer peripheral surface of the rotating body.

In one aspect, the at least one cleaning liquid discharge port includes a plurality of cleaning liquid discharge ports. The plurality of cleaning liquid discharge ports are arranged along a circumferential direction of the inner cover part.

In one aspect, the at least one cleaning liquid discharge port is arranged below a limit height that is set within the outer peripheral surface of the rotating body and that allows contact with liquid.

In one aspect, the at least one cleaning liquid discharge port is arranged below the cleaning liquid supply port.

In one aspect, the cover cleaning part covers an entire circumference of the outer peripheral surface of the rotating body. The at least one cleaning liquid discharge port is arranged to face the entire circumference of the outer peripheral surface of the rotating body.

In one aspect, the cover assembly includes a first cover member constituting at least a portion of the cover assembly, and a second cover member constituting another portion of the cover assembly. At least one of the first cover member and the second cover member is configured to be removable from the polishing apparatus. At least one of the first cover member and the second cover member includes the cover cleaning part.

In one aspect, the rotating body is a polishing head for pressing a substrate against a polishing surface.

In one aspect, provided is a cleaning method for cleaning the rotating body using the cover assembly described above. The cleaning method includes the following. While the rotating body is being rotated, the cleaning liquid is discharged from the at least one cleaning liquid discharge port toward the outer peripheral surface of the rotating body and the cleaning liquid is supplied to a gap between the rotating body and the cover assembly, thereby cleaning the outer peripheral surface of the rotating body and an inner peripheral surface of the cover assembly.

In one aspect, provided is a method for manufacturing the cover assembly described above. The method includes the following. The outer cover part is molded by a vacuum forming method. The vacuum forming method includes the following processes. A thin plate is heated and the thin plate is softened. The thin plate that has been softened is closely attached to a mold by vacuum suction. The thin plate closely attached to the mold is cooled. The thin plate that has been cooled is released from the mold.

According to the disclosure, since the rotating body such as the polishing head is covered by the cover assembly, adhesion of a polishing liquid to the rotating body can be prevented. The cover assembly includes the cover cleaning part covering at least a portion of the outer peripheral surface of the rotating body. By supplying the cleaning liquid to the gap between the rotating body and the cover assembly, the outer peripheral surface of the rotating body and the inner peripheral surface of the cover assembly are cleaned. Accordingly, the polishing liquid adhering to the outer peripheral surface of the polishing head and the inner peripheral surface of the cover assembly can be prevented from drying, and particles formed from dried polishing liquid can be prevented from falling onto a polishing pad. As a result, scratches on the substrate can be prevented.

Further, according to the disclosure, the outer cover part of the cover cleaning part can be molded with high dimensional accuracy by the vacuum forming method. Accordingly, distortion of the fluid chamber formed between the outer cover part and the inner cover part due to deformation of the outer cover part can be prevented, and the cleaning liquid can be stably supplied to the gap between the rotating body and the cover assembly.

Hereinafter, embodiments of the disclosure are described with reference to the drawings.

FIG. 1 is a perspective view illustrating one embodiment of a polishing apparatus that polishes a substrate W such as a wafer. As illustrated in FIG. 1, the polishing apparatus includes: a polishing table 3, for supporting a polishing pad 2 as a polishing tool; a polishing head 5, for pressing the substrate W against the polishing pad 2 on the polishing table 3; a table motor 6, rotating the polishing table 3 together with the polishing pad 2; and a polishing liquid supply nozzle 8, for supplying a polishing liquid (for example, slurry) to the polishing pad 2.

The polishing pad 2 is attached to an upper surface of the polishing table 3. An exposed surface of the polishing pad 2 constitutes a polishing surface 2a that polishes the substrate W. As the polishing tool, fixed abrasive grains, polishing cloth or the like may be used instead of the polishing pad 2. The table motor 6 is arranged below the polishing table 3. The polishing table 3 is connected to the table motor 6 via a table shaft 3a. The polishing table 3 and the polishing pad 2 are rotated about a shaft center of the table shaft 3a by the table motor 6.

The polishing apparatus further includes: a head shaft 11, connected to the polishing head 5; a head swing shaft 14; and a head swing arm 16, connected to an upper end of the head swing shaft 14. The polishing head 5 is fixed to a lower end of the head shaft 11. The polishing head 5 is configured to be able to hold the substrate W on its lower surface by vacuum suction. The substrate W is held so that a surface to be polished faces downward.

The head shaft 11 is rotatably supported at a free end of the head swing arm 16. A head swing mechanism (not illustrated) including an electric motor or the like is arranged inside the head swing arm 16. The head swing mechanism is connected to the head swing shaft 14. The head swing mechanism is configured to swing the polishing head 5 together with the head shaft 11 about a shaft center of the head swing shaft 14 via the head swing arm 16. When the head swing arm 16 is swung by the head swing mechanism, the polishing head 5 moves between a polishing position above the polishing table 3 and a standby position radially outside the polishing table 3.

A head rotation mechanism (not illustrated) including an electric motor or the like is arranged inside the head swing arm 16. This head rotation mechanism is connected to the head shaft 11, and is configured to rotate the polishing head 5 together with the head shaft 11 about a shaft center of the head shaft 11. The head rotation mechanism is composed of, for example, a combination of a motor, a pulley, and a belt.

The head shaft 11 is connected to a head lifting and lowering mechanism (not illustrated). This head lifting and lowering mechanism is configured to move the head shaft 11 up and down relative to the head swing arm 16. The head lifting and lowering mechanism is composed of, for example, a combination of a ball screw and a servo motor. This up and down movement of the head shaft 11 allows the polishing head 5 to move up and down relative to the head swing arm 16 and the polishing table 3.

The polishing apparatus further includes an operation control part 20. The polishing head 5, the table motor 6, the head swing mechanism, the head rotation mechanism, the head lifting and lowering mechanism, and the polishing liquid supply nozzle 8 are electrically connected to the operation control part 20. Operations of the polishing head 5, the table motor 6, the head swing mechanism, the head rotation mechanism, the head lifting and lowering mechanism, and the polishing liquid supply nozzle 8 are controlled by the operation control part 20.

The operation control part 20 is composed of at least one computer. The operation control part 20 includes a storage device 20a that stores a program for controlling an operation of the polishing apparatus, and an arithmetic device 20b that executes a calculation in accordance with a command included in the program. The storage device 20a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) and a solid state drive (SSD). Examples of the arithmetic device 20b include a central processing unit (CPU) and a graphic processing unit (GPU). However, a specific configuration of the operation control part 20 is not limited to these examples.

The substrate W is polished as follows. The polishing head 5 holding the substrate W is moved from the standby position to the polishing position. While the polishing head 5 and the polishing table 3 are rotated in the same direction, the polishing liquid is supplied from the polishing liquid supply nozzle 8 to the polishing surface 2a of the polishing pad 2. While being rotated by the polishing head 5, the substrate W is pressed against the polishing surface 2a of the polishing pad 2 by the polishing head 5 while the polishing liquid is present on the polishing pad 2. The surface of the substrate W is polished by a chemical action of the polishing liquid and a mechanical action of abrasive grains contained in the polishing liquid and/or the polishing pad 2.

The polishing apparatus further includes a dresser 30 that dresses (or conditions) the polishing surface 2a of the polishing pad 2. The dresser 30 includes: a dressing head 31, slidably connected to the polishing pad 2; a dresser shaft 33, to which the dressing head 31 is fixed; a dresser arm 35, supporting the dresser shaft 33; a dresser rotation mechanism (not illustrated), rotating the dressing head 31 via the dresser shaft 33. The dresser rotation mechanism is arranged inside the dresser arm 35. Abrasive grains (not illustrated) such as diamond particles are fixed to a lower surface of the dressing head 31. The lower surface of the dressing head 31 constitutes a dressing surface that dresses the polishing surface 2a with these abrasive grains.

The dresser arm 35 is connected to a dresser swing shaft 37 and is configured to pivot about the dresser swing shaft 37. When the dresser arm 35 pivots, the dressing head 31 swings on the polishing surface 2a in the radial direction of the polishing table 3. The dressing head 31 rotates while swinging on the polishing surface 2a of the polishing pad 2, and dresses the polishing surface 2a by slightly scraping off the polishing pad 2. Furthermore, as the dresser arm 35 pivots, the dressing head 31 moves between a dressing position above the polishing table 3 and a standby position radially outside the polishing table 3.

The polishing apparatus further includes an atomizer 39 that sprays an atomized fluid onto the polishing surface 2a of the polishing pad 2 and cleans the polishing surface 2a. The atomizer 39 extends along the radial direction of the polishing pad 2 (or the polishing table 3). The fluid is composed of a mixed fluid of a liquid (for example, pure water) and a gas (for example, inert gas such as nitrogen gas), or only a liquid. By spraying such a fluid onto the polishing surface 2a, polishing debris and the abrasive particles contained in the polishing liquid, which remain on the polishing surface 2a of the polishing pad 2, are removed.

As illustrated in FIG. 1, the polishing apparatus further includes a head accessory device 40 mounted on an upper part of the polishing head 5. The head accessory device 40 is a device that should be prevented from contact with liquid such as the polishing liquid. Examples of the head accessory device 40 include a local load application device for applying a local load to a portion of the polishing head 5. A specific configuration of the head accessory device 40 is not limited to the local load application device, and is arbitrary as long as the head accessory device 40 is a device that should be prevented from contact with liquid. In FIG. 1, the head accessory device 40 is schematically depicted.

The polishing apparatus of the present embodiment includes a cover assembly 41 that covers the upper part of the polishing head 5. The cover assembly 41 is open at its lower end and has a shape surrounding an outer peripheral surface of the polishing head 5. In the present embodiment, the polishing head 5 has a columnar shape, and the cover assembly 41 has a circular horizontal cross section. An upper end of the cover assembly 41 is connected to a lower surface of the head swing arm 16 using a fastener such as a screw (not illustrated). The cover assembly 41 has a shape accommodating the head shaft 11 and the head accessory device 40 therein and further covering the upper part of the polishing head 5. Accordingly, the polishing liquid can be prevented from entering the upper part of the polishing head 5 and from adhering to the polishing head 5 including the head accessory device 40 and the like.

FIG. 2 is a perspective view illustrating one embodiment of the cover assembly 41. The cover assembly 41 includes a cover body 42 that covers the outer peripheral surface of the polishing head 5 (not illustrated in FIG. 2), and a flange 43 for connecting to the lower surface of the head swing arm 16 (not illustrated in FIG. 2). The cover body 42 is connected to the flange 43 and has a cylindrical shape extending downward from the flange 43. The cover assembly 41 may have any other shape as long as it is able to cover the upper part of the polishing head 5, and is not limited to the present embodiment. In one embodiment, the cover body 42 may have any other shape such as an elliptical shape or a prismatic shape, depending on the shape of the polishing head 5. In another embodiment, the cover assembly 41 may not include the flange 43, and may be connected to the head swing arm 16 via a bracket (not illustrated).

The cover assembly 41 may be configured to be divisible into two or more cover members. In the present embodiment, the cover assembly 41 includes a first cover member 45A constituting at least a portion of the cover assembly 41, and a second cover member 45B constituting another portion of the cover assembly 41. More specifically, the cover assembly 41 includes the first cover member 45A constituting half of the cover assembly 41 in a circumferential direction, and the second cover member 45B constituting the remaining half of the cover assembly 41 in the circumferential direction. Both ends of the first cover member 45A are in contact with both ends of the second cover member 45B, respectively. In the present embodiment, both ends of the first cover member 45A overlap both ends of the second cover member 45B. However, the configurations of the first cover member 45A and the second cover member 45B are not limited to the present embodiment. In one embodiment, both ends of the first cover member 45A and both ends of the second cover member 45B may be connected to each other by a fastener such as a screw (not illustrated). In one embodiment, the cover assembly 41 may be integrally molded or may be composed of three or more cover members.

The first cover member 45A includes a first cover body 42a constituting half of the cover body 42 in the circumferential direction, and a first flange 43a connected to an upper part of the first cover body 42a and constituting half of the flange 43. The second cover member 45B includes a second cover body 42b constituting the remaining half of the cover body 42 in the circumferential direction, and a second flange 43b connected to an upper part of the second cover body 42b and constituting the remaining half of the flange 43. The first cover body 42a and the second cover body 42b have a semi-cylindrical shape.

At least one of the first cover member 45A and the second cover member 45B is configured to be removable from the polishing apparatus. In the present embodiment, both the first cover member 45A and the second cover member 45B are removable from the polishing apparatus by removing a fastener of the flange 43. According to such a configuration, maintenance of the polishing head 5 or the head accessory device 40 or the like covered by the cover assembly 41 can be easily performed.

The flange 43 and the cover body 42 are composed of separate members, and are joined by welding or bonding using an adhesive. In the present embodiment, the first flange 43a and the first cover body 42a are composed of separate members, and the second flange 43b and the second cover body 42b are composed of separate members.

The cover body 42 includes a cover cleaning part 48 that cleans the outer peripheral surface of the polishing head 5 and an inner peripheral surface of the cover assembly 41. The cover cleaning part 48 includes therein a fluid chamber 55 where a cleaning liquid for cleaning the outer peripheral surface of the polishing head 5 and the inner peripheral surface of the cover assembly 41 flows. Details of the fluid chamber 55 will be described later. The cover cleaning part 48 is configured to cover at least a portion of the outer peripheral surface of the polishing head 5. In the present embodiment, the cover cleaning part 48 is configured to cover an entire circumference of the outer peripheral surface of the polishing head 5, and is composed of the entire cover body 42. That is, the cover cleaning part 48 of the present embodiment is composed of the first cover body 42a and the second cover body 42b.

In one embodiment, the cover cleaning part 48 may be composed of a portion of the cover body 42 and may be configured to cover a portion of the outer peripheral surface of the polishing head 5. For example, the cover cleaning part 48 may be composed of the first cover body 42a, and the second cover body 42b may be a semi-cylindrical member that does not have a configuration as the cover cleaning part 48 (that is, does not include the fluid chamber 55), the details of which will be described later. Since the member that does not have the configuration as the cover cleaning part 48 can be reduced in width compared to the cover cleaning part 48 including the fluid chamber 55, a portion having a small distance from an apparatus (for example, the polishing liquid supply nozzle 8 or the atomizer 39 illustrated in FIG. 1) provided adjacent to the polishing head 5 may be composed of the member that does not have the configuration as the cover cleaning part 48. In other words, at least one of the first cover member 45A and the second cover member 45B includes the cover cleaning part 48. In the present embodiment, both the first cover member 45A and the second cover member 45B include the cover cleaning part 48.

In the present embodiment, the cover cleaning part 48 includes a first cover cleaning part 48A composed of the first cover body 42a, and a second cover cleaning part 48A composed of the second cover body 42b.

Next, the configuration of the cover cleaning part 48 is described. Since the first cover cleaning part 48A and the second cover cleaning part 48B basically have the same configuration, the first cover cleaning part 48A is described below. FIG. 3 is a perspective view illustrating one embodiment of the first cover cleaning part 48A. FIG. 4 illustrates an inner surface of the first cover cleaning part 48A illustrated in FIG. 3. FIG. 5 is a cross-sectional view taken on line A-A in FIG. 4. FIG. 6 is a cross-sectional view taken on line B-B in FIG. 4. The first cover cleaning part 48A includes: an outer cover part 51, constituting an outer surface of the first cover cleaning part 48A; an inner cover part 52, constituting at least a portion of the inner surface of the first cover cleaning part 48A; and the fluid chamber 55, formed between the outer cover part 51 and the inner cover part 52.

As illustrated in FIG. 5, the outer cover part 51 includes a fluid chamber formation part 51a located outside the inner cover part 52, and a wall 51b located on an upper side of the fluid chamber formation part 51a. The fluid chamber formation part 51a has a shape recessed radially outward. As illustrated in FIG. 3 and FIG. 4, the inner cover part 52 includes a main cover part 52a having an arc shape, and a joint part 52b projecting upward from the main cover part 52a. The outer surface of the first cover cleaning part 48A is constituted by an outer surface of the outer cover part 51. The inner surface of the first cover cleaning part 48A is constituted by an inner surface of the inner cover part 52 and an inner surface of the wall 51b of the outer cover part 51, which are within the same plane. At least a portion of the inner surface of the first cover cleaning part 48A faces the outer peripheral surface of the polishing head 5 (see FIG. 1). In one embodiment, the outer cover part 51 may not include the wall 51b.

The outer cover part 51 includes, within the wall 51b, a joint fitting part 51c into which the joint part 52b of the inner cover part 52 is fitted. The inner cover part 52 is smaller than the outer cover part 51. The inner cover part 52 has the joint part 52b fitted into the joint fitting part 51c of the outer cover part 51, and the entire inner cover part 52 is fitted into the outer cover part 51. The outer cover part 51 and the inner cover part 52 are joined using an adhesive or the like.

As illustrated in FIG. 5, the fluid chamber 55 is formed between the outer cover part 51 and the inner cover part 52. More specifically, the fluid chamber 55 is formed between the fluid chamber formation part 51a of the outer cover part 51 and the main cover part 52a of the inner cover part 52. The fluid chamber 55 is formed along the circumferential direction of the first cover cleaning part 48A. In one embodiment, a thickness T1 of a sidewall of the fluid chamber formation part 51a, a thickness T2 of the inner cover part 52, and a width F1 of the fluid chamber 55 are the same. In one embodiment, a thickness of the wall 51b of the outer cover part 51 is larger than the thickness T1 of the sidewall of the fluid chamber formation part 51a, and is the same as the sum of the thickness T1 of the sidewall of the fluid chamber formation part 51a, the thickness T2 of the inner cover part 52, and the width F1 of the fluid chamber 55.

A height dimension of the fluid chamber 55 is determined depending on a height dimension of the fluid chamber formation part 51a of the outer cover part 51. In a cross section of the first cover cleaning part 48A illustrated in FIG. 5 that does not pass through the joint fitting part 51c of the outer cover part 51, the height dimension of the fluid chamber 55 is H1. In a cross section of the first cover cleaning part 48A illustrated in FIG. 6 that passes through the joint fitting part 51c of the outer cover part 51, the height dimension of the fluid chamber 55 is H2. The height dimension H2 is greater than the height dimension H1. That is, the fluid chamber 55 expands upward at a position of the joint fitting part 51c of the outer cover part 51.

The first cover cleaning part 48A further includes a cleaning liquid supply port 57 for supplying the cleaning liquid to the fluid chamber 55. The cleaning liquid supply port 57 is provided in the outer cover part 51 or the inner cover part 52. In the present embodiment, as illustrated in FIG. 3, the cleaning liquid supply port 57 is provided in the joint part 52b of the inner cover part 52. As illustrated in FIG. 6, the cleaning liquid supply port 57 communicates with a supply channel 52c formed in the inner cover part 52, and communicates with the fluid chamber 55 via the supply channel 52c.

The cleaning liquid supply port 57 is connected to a cleaning liquid supply line (not illustrated) that supplies the cleaning liquid. The cleaning liquid supplied from the cleaning liquid supply line flows from the cleaning liquid supply port 57 through the supply channel 52c and is supplied into the fluid chamber 55. Examples of the cleaning liquid include pure water. In one embodiment, the cleaning liquid supply port 57 may be provided in the main cover part 52a of the inner cover part 52, or may be provided in the fluid chamber formation part 51a of the outer cover part 51. In one embodiment, the first cover cleaning part 48A may include a plurality of cleaning liquid supply ports 57. For example, the plurality of cleaning liquid supply ports 57 may be arranged at equal intervals along the circumferential direction of the inner cover part 51. A flow rate of the cleaning liquid supplied from the cleaning liquid supply line or the number and arrangement of the cleaning liquid supply port 57 are determined as appropriate according to a flow rate of the cleaning liquid discharged from a cleaning liquid discharge port 58 to be described later.

The inner cover part 51 includes at least one cleaning liquid discharge port 58 communicating with the fluid chamber 55. In the present embodiment, the inner cover part 51 includes a plurality of cleaning liquid discharge ports 58 arranged along the circumferential direction of the inner cover part 51. The plurality of cleaning liquid discharge ports 58 are arranged at equal intervals along the circumferential direction of the inner cover part 51. The plurality of cleaning liquid discharge ports 58 are arranged below the cleaning liquid supply port 57. The shape and arrangement of the cleaning liquid discharge port 58 are not limited to the present embodiment. For example, the inner cover part 51 may include one cleaning liquid discharge port 58 in the shape of a slit extending along the circumferential direction of the inner cover part 51. In one embodiment, the plurality of cleaning liquid discharge ports 58 may be arranged irregularly along the circumferential direction of the inner cover part 51.

As illustrated in FIG. 6, the cleaning liquid discharge port 58 communicates with the fluid chamber 55 via a discharge channel 52d formed in the inner cover part 52. The cleaning liquid discharge port 58 communicates with the discharge channel 52d. In the present embodiment, the cleaning liquid discharge port 58 and the discharge channel 52d are formed in a lower part of the inner cover part 52, and are located at a lower part of the fluid chamber 55. However, in one embodiment, the cleaning liquid discharge port 58 and the discharge channel 52d may be located at a lowermost part of the fluid chamber 55. In the present embodiment, the discharge channel 52d extends horizontally. However, in one embodiment, the discharge channel 52d may be inclined downward from the fluid chamber 55 side toward the cleaning liquid discharge port 58 side. The cleaning liquid in the fluid chamber 55 flows through the discharge channel 52d and is discharged from the cleaning liquid discharge port 58 to the outside of the first cover cleaning part 48A. The cleaning liquid discharge port 58 is arranged to face the outer peripheral surface of the polishing head 5 (see FIG. 1). Accordingly, the cleaning liquid in the fluid chamber 55 is discharged from the cleaning liquid discharge port 58 toward the outer peripheral surface of the polishing head 5.

As described above, half of the cover cleaning part 48 is composed of the first cover cleaning part 48A, and the remaining half of the cover cleaning part 48 is composed of the second cover cleaning part 48B. Accordingly, the cover cleaning part 48 covers the entire circumference of the outer peripheral surface of the polishing head 5. A plurality of cleaning liquid discharge ports of the cover cleaning part 48, which include a plurality of cleaning liquid discharge ports 58 of the first cover cleaning part 48A and a plurality of cleaning liquid discharge ports (not illustrated) of the second cover cleaning part 48B, are arranged to face the entire circumference of the outer peripheral surface of the polishing head 5.

FIG. 7 illustrates a state in which the cover cleaning part 48 cleans an outer peripheral surface 5a of the polishing head 5 and an inner peripheral surface 41a of the cover assembly 41. The cover cleaning part 48 discharges the cleaning liquid in the fluid chamber 55 from a plurality of cleaning liquid discharge ports 58 toward the outer peripheral surface 5a of the polishing head 5, and supplies the cleaning liquid to a gap G between the polishing head 5 and the cover assembly 41. An inner diameter of the cover assembly 41 is larger than an outer diameter of the polishing head 5, and the gap G is formed between the polishing head 5 and the cover assembly 41 over the entire circumference of the polishing head 5. A width of the gap G between the polishing head 5 and the cover assembly 41 is set to such an extent (for example, about several millimeters) that the cleaning liquid is able to contact the entire circumference of the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41, and the cleaning liquid supplied from the cleaning liquid discharge port 58 is able to clean the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41.

The plurality of cleaning liquid discharge ports 58 of the cover cleaning part 48 are arranged below a limit height LH that is set within the outer peripheral surface 5a of the polishing head 5 and that allows contact with liquid. The limit height LH is determined in advance to a height at which the cleaning liquid can be prevented from entering the upper part of the polishing head 5 and from adhering to the polishing head 5 including the head accessory device 40 and the like.

Cleaning of the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41 by the cover cleaning part 48 is performed between when polishing of the substrate W is ended and when polishing of the next substrate is started. During cleaning, the polishing head 5 is arranged in the standby position radially outside the polishing table 3. The cover cleaning part 48 discharges the cleaning liquid in the fluid chamber 55 from the plurality of cleaning liquid discharge ports 58 toward the outer peripheral surface 5a of the polishing head 5 that rotates, and supplies the cleaning liquid to the gap G between the polishing head 5 and the cover assembly 41. In particular, the cleaning liquid is supplied to the gap G between the polishing head 5 and the cover assembly 41 and located below the plurality of cleaning liquid discharge ports 58. Since the cleaning liquid is supplied to the gap G from the plurality of cleaning liquid discharge ports 58 while the polishing head 5 is being rotated, the cleaning liquid is spread over the entire circumference of the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41. More specifically, when the cleaning liquid is supplied to the gap G during rotation of the polishing head 5, as the cleaning liquid fills the entire circumference of the gap G due to surface tension, a discharge force of the cleaning liquid from the cleaning liquid discharge port 58 and a rotational force of the polishing head 5 act, and the cleaning liquid contacts the entire circumference of the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41. Accordingly, the polishing liquid adhering to the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41 can be washed away.

The flow rate of the cleaning liquid discharged from the cleaning liquid discharge port 58 can be adjusted according to the flow rate of the cleaning liquid supplied to the fluid chamber 55 from the cleaning liquid supply line (not illustrated) described above. When the flow rate of the cleaning liquid supplied to the fluid chamber 55 from the cleaning liquid supply line (not illustrated) is increased, the cleaning liquid is vigorously discharged from the cleaning liquid discharge port 58 toward the outer peripheral surface 5a of the polishing head 5. Accordingly, the polishing liquid adhering to the outer peripheral surface 5a of the polishing head 5 can be relatively effectively washed away.

The cleaning liquid discharge port 58 of the present embodiment is arranged to face the entire circumference of the outer peripheral surface 5a of the polishing head 5. However, in one embodiment, the cleaning liquid discharge port 58 may be arranged to face a portion of the outer peripheral surface 5a of the polishing head 5. As long as the cleaning liquid is spread over the entire circumference of the outer peripheral surface 5a of the polishing head 5 and the inner peripheral surface 41a of the cover assembly 41 by rotation of the polishing head 5, the shape and arrangement of the cleaning liquid discharge port 58 are not particularly limited.

To avoid contact between the cover assembly 41 and the apparatus (for example, the polishing liquid supply nozzle 8 or the atomizer 39 illustrated in FIG. 1) provided adjacent to the polishing head 5, an outer diameter dimension of the cover assembly 41 is limited. Accordingly, the thickness T1 of the sidewall of the fluid chamber formation part 51a, the thickness T2 of the inner cover part 52, and the width F1 of the fluid chamber 55, which are illustrated in FIG. 5, are limited. For example, the thickness T1 of the sidewall of the fluid chamber formation part 51a, the thickness T2 of the inner cover part 52, and the width F1 of the fluid chamber 55 are each about several millimeters.

When the fluid chamber formation part 51a of the outer cover part 51 having such a small thickness is molded by cutting or the like, the fluid chamber formation part 51a may be deformed by heat during machining. When the fluid chamber formation part 51a is deformed, the fluid chamber 55 is distorted. As a result, the cleaning liquid may not be able to be uniformly discharged from the plurality of cleaning liquid discharge ports 58. Accordingly, high dimensional accuracy is required for molding the fluid chamber formation part 51a of the outer cover part 51.

In one embodiment, the outer cover part 51 is molded by a vacuum forming method. FIG. 8 illustrates one embodiment of the vacuum forming method for molding the outer cover part 51. The outer cover part 51 of the present embodiment is made of thermoplastic resin. Examples of the thermoplastic resin used as a material of the outer cover part 51 include polyvinyl chloride (PVC), polypropylene (PP), and polyethylene (PE).

In step S101, a thin plate 60 being a material of the outer cover part 51 is heated by a heater 62, and the thin plate 60 is softened.

In step S102, the softened thin plate 60 is closely attached to a mold 63 by vacuum suction. A through hole 63a for vacuum suction is formed in the mold 63. Through the through hole 63a, a vacuum is created between the mold 63 and the thin plate 60. The softened thin plate 60 is closely attached to the mold 63 while being deformed in accordance with the shape of the mold 63.

In step S103, the thin plate 60 closely attached to the mold 63 is cooled. The thin plate 60 that has been softened by heat is hardened by being cooled, and its shape is fixed.

In step S104, the cooled thin plate 60, that is, the molded outer cover part 51, is released from the mold. According to such a vacuum forming method, the fluid chamber formation part 51a of the outer cover part 51 can be molded with high dimensional accuracy. In particular, since the fluid chamber formation part 51a of the outer cover part 51 is a portion closely attached to the mold 63, the fluid chamber formation part 51a is molded in dimensions according to the shape of the mold 63. Accordingly, the fluid chamber formation part 51a that forms the fluid chamber 55 can be molded with high dimensional accuracy. In the outer cover part 51 of the present embodiment, the thin plate 60 having a uniform thickness is deformed in accordance with the shape of the mold 63. Accordingly, an overall shape of the outer cover part 51 of the present embodiment is different from an overall shape of the outer cover part 51 of the embodiments described above. In one embodiment, the thickness of the sidewall of the fluid chamber formation part 51a and the thickness of the wall 51b may be the same. In another embodiment, the fluid chamber formation part 51a and the wall 51b of the outer cover part 51 may be separately molded and then joined by welding or bonding using an adhesive.

The cover assembly described so far is applied as a cover that covers the polishing head 5. However, the cover assembly can also be applied to any rotating body used in the polishing apparatus. Examples of the rotating body used in the polishing apparatus include, in addition to the polishing head 5, the dressing head 31. FIG. 9 illustrates an example in which a cover assembly 80 is applied to the dressing head 31. Since the cover assembly 80 applied to the dressing head 31 has the same configuration as the cover assembly 41 described above, repeated description is omitted.

The above-mentioned embodiments are described in order for those of ordinary skill in the art to implement the disclosure. Various modifications to the above embodiments can, of course, be achieved by those skilled in the art, and the technical idea of the disclosure can also be applied in other embodiments. Accordingly, the disclosure is not limited to the embodiments described herein and is to be interpreted in the broadest scope in accordance with the technical idea defined by the claims.

Claims

1. A cover assembly, for cleaning a rotating body used in a polishing apparatus, the cover assembly comprising:

a cover cleaning part, covering at least a portion of an outer peripheral surface of the rotating body, and comprising: an outer cover part, constituting an outer surface of the cover cleaning part; an inner cover part, constituting at least a portion of an inner surface of the cover cleaning part; a fluid chamber, formed between the outer cover part and the inner cover part; and a cleaning liquid supply port, provided in the outer cover part or the inner cover part, communicating with the fluid chamber, and for supplying a cleaning liquid to the fluid chamber, wherein the inner cover part comprises at least one cleaning liquid discharge port communicating with the fluid chamber and facing the outer peripheral surface of the rotating body.

2. The cover assembly according to claim 1, wherein

the at least one cleaning liquid discharge port comprises a plurality of cleaning liquid discharge ports; and

the plurality of cleaning liquid discharge ports are arranged along a circumferential direction of the inner cover part.

3. The cover assembly according to claim 1, wherein

the at least one cleaning liquid discharge port is arranged below a limit height that is set within the outer peripheral surface of the rotating body and that allows contact with liquid.

4. The cover assembly according to claim 1, wherein

the at least one cleaning liquid discharge port is arranged below the cleaning liquid supply port.

5. The cover assembly according to claim 1, wherein

the cover cleaning part covers an entire circumference of the outer peripheral surface of the rotating body; and

the at least one cleaning liquid discharge port is arranged to face the entire circumference of the outer peripheral surface of the rotating body.

6. The cover assembly according to claim 1, wherein

the cover assembly comprises a first cover member constituting at least a portion of the cover assembly, and a second cover member constituting another portion of the cover assembly;

at least one of the first cover member and the second cover member is configured to be removable from the polishing apparatus; and

at least one of the first cover member and the second cover member comprises the cover cleaning part.

7. The cover assembly according to claim 1, wherein

the rotating body is a polishing head for pressing a substrate against a polishing surface.

8. A cleaning method, for cleaning a rotating body used in a polishing apparatus using the cover assembly according to claim 1, the cleaning method comprising:

while rotating the rotating body, discharging the cleaning liquid from the at least one cleaning liquid discharge port toward the outer peripheral surface of the rotating body and supplying the cleaning liquid to a gap between the rotating body and the cover assembly, thereby cleaning the outer peripheral surface of the rotating body and an inner peripheral surface of the cover assembly.

9. A method for manufacturing the cover assembly according to claim 1, comprising:

molding the outer cover part by a vacuum forming method, wherein the vacuum forming method comprises processes of: heating a thin plate and softening the thin plate; closely attaching the thin plate that has been softened to a mold by vacuum suction; cooling the thin plate closely attached to the mold; and releasing the thin plate that has been cooled from the mold.