SUBSTRATE HOLDING DEVICE, SUBSTRATE PROCESSING APPARATUS, SUBSTRATE PROCESSING METHOD, AND STORAGE MEDIUM

Abstract

A substrate holding device capable of eliminating a variation in a film thickness of a substrate is disclosed. The substrate holding device includes an offset mechanism configured to offset a carrier with respect to a retaining ring.

Description

CROSS REFERENCE TO RELATED APPLICATION

This document claims priority to Japanese Patent Application No. 2023-112875 filed Jul. 10, 2023, the entire contents of which are hereby incorporated by reference.

BACKGROUND

In a manufacture of semiconductor devices, various types of films are formed on a wafer, which is an example of a substrate. After the film formation process, the wafer is polished to remove unnecessary parts of the film and surface irregularities. A chemical mechanical polishing (CMP) is a typical technique for wafer polishing.

The CMP is performed by bringing a wafer into sliding contact with a polishing surface while supplying a slurry onto a polishing surface. The film formed on the wafer is polished by a combination of a mechanical action of abrasive grains contained in the slurry and a chemical action of the chemical components of the slurry.

The process of forming the film on the wafer is carried out using various deposition techniques such as plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), etc. In these deposition techniques, the film may not be formed uniformly over the entire surface of the wafer. For example, there may be variations in film thickness along the circumferential direction of the wafer.

However, it is difficult to eliminate such variations in the film thickness of the wafer (e.g., variations in the film thickness along a circumferential direction) with conventional CMP techniques. Therefore, if the film on the wafer is polished uniformly, there is a risk that variations in the film thickness will remain on the wafer.

SUMMARY

Therefore, there are provided a substrate holding device, a substrate processing apparatus, a substrate processing method, and a storage medium capable of eliminating the variation in a film thickness of the substrate.

Embodiments, which will be described below, relate to a substrate holding device, a substrate processing apparatus, a substrate processing method, and a storage medium.

In an embodiment, there is provided a substrate holding device, comprising: an elastic membrane configured to form at least one pressure chamber for pressing a substrate; a carrier coupled to the elastic membrane; a retaining ring surrounding the carrier; and an offset mechanism configured to offset the carrier relative to the retaining ring.

In an embodiment, the substrate holding device comprises a tilting structure configured to tilt the retaining ring.

In an embodiment, the tilting structure is arranged in an accommodation recess of the carrier and comprises a spherical bearing mounted on a shaft portion of the retaining ring.

In an embodiment, the tilting structure comprises a ball joint coupling the retaining ring and a head shaft.

In an embodiment, the offset mechanism comprises a plurality of pressing actuators supported by the carrier, and each of the pressing actuators applies a pressing force to the carrier.

In an embodiment, the offset mechanism comprises a plurality of pressing actuators supported by the retaining ring and configured to apply a pressing force to the carrier.

In an embodiment, the substrate holding device comprises a rotational torque transmission mechanism configured to transmit a rotational torque acting on the retaining ring to the carrier.

In an embodiment, there is provided a substrate processing apparatus, comprising: a substrate holding device described above; a polishing table configured to support a polishing pad having a polishing surface against which a substrate held by the substrate holding device is pressed; and a control device configured to control an operation of the substrate holding device, wherein the control device is configured to: determine an eccentricity direction and an eccentricity of a carrier based on a film thickness distribution of the substrate measured during polishing of the substrate; and operate an offset mechanism to offset the carrier based on the determined eccentricity direction and eccentricity.

In an embodiment, the control device is configured to: determine whether or not a relative angle of the substrate to the substrate holding device has changed when measuring the film thickness distribution of the substrate; and when the relative angle has changed, correct the relative angle based on the amount of change in the relative angle to determine the eccentricity direction and the eccentricity of the carrier.

In an embodiment, the control device is configured to: after starting polishing of the substrate, determine whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; when the current film thickness distribution is within the first target film thickness distribution range, operate the offset mechanism to return the carrier to an initial position; and when the current film thickness distribution is not within the first target film thickness distribution range, check whether the eccentricity direction and the eccentricity of the carrier correspond to the film thickness distribution of the substrate.

In an embodiment, the control device is configured to: after starting polishing of the substrate, determine whether or not the current film thickness distribution in a radial direction of the substrate is within a predetermined second target film thickness distribution range; when the current film thickness distribution is within the second target film thickness distribution range, determine whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; and when the current film thickness distribution is not within the second target film thickness distribution range, operate a pressure regulation device to change a pressure of a fluid supplied to a pressure chamber.

In an embodiment, there is provided a substrate processing method, comprising: pressing a substrate held by a substrate holding device against a polishing surface of a polishing pad to polish the substrate; determining an eccentricity direction and an eccentricity of a carrier coupled to an elastic membrane forming at least one pressure chamber for pressing the substrate based on a film thickness distribution of the substrate measured during polishing of the substrate; and operating an offset mechanism configured to offset the carrier based on the determined eccentricity direction and eccentricity to offset the carrier.

In an embodiment, comprising: determining whether or not a relative angle of the substrate to the substrate holding device has changed when measuring the film thickness distribution of the substrate; and when the relative angle has changed, correcting the relative angle based on the amount of change in the relative angle to determine the eccentricity direction and the eccentricity of the carrier.

In an embodiment, comprising: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; when the current film thickness distribution is within the first target film thickness distribution range, operating the offset mechanism to return the carrier to an initial position; and when the current film thickness distribution is not within the first target film thickness distribution range, checking whether the eccentricity direction and the eccentricity of the carrier correspond to the film thickness distribution of the substrate.

In an embodiment, comprising: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a radial direction of the substrate is within a predetermined second target film thickness distribution range; when the current film thickness distribution is within the second target film thickness distribution range, determining whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; and when the current film thickness distribution is not within the second target film thickness distribution range, operating a pressure regulation device to change a pressure of a fluid supplied to the pressure chamber.

In an embodiment, there is provided a non-transitory computer-readable storage medium storing a program for causing a computer to perform the steps of: causing a substrate holding device to perform an operation of pressing a substrate against a polishing surface of a polishing pad to polish the substrate; determining an eccentricity direction and an eccentricity of a carrier coupled to an elastic membrane configured to form at least one pressure chamber for pressing the substrate based on a film thickness distribution of the substrate measured during polishing of the substrate; and causing an offset mechanism to perform an operation of offsetting the carrier based on the determined eccentricity direction and eccentricity.

In an embodiment, which causes the computer to perform the steps of: determining whether or not a relative angle of the substrate with respect to the substrate holding device has changed when measuring the film thickness distribution of the substrate; and when the relative angle has changed, correcting the relative angle based on the amount of change in the relative angle to determine the eccentricity direction and the eccentricity of the carrier.

In an embodiment, which causes the computer to perform the steps of: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; when the current film thickness distribution is within the first target film thickness distribution range, causing the offset mechanism to perform an operation of returning the carrier to an initial position; and when the current film thickness distribution is not within the first target film thickness distribution range, checking whether the eccentricity direction and the eccentricity of the carrier correspond to the film thickness distribution of the substrate.

In an embodiment, which causes the computer to perform the steps of: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a radial direction of the substrate is within a predetermined second target film thickness distribution range; when the current film thickness distribution is within the second target film thickness distribution range, determining whether or not the current film thickness distribution in the circumferential direction of the substrate is within a predetermined first target film thickness distribution range; and when the current film thickness distribution is not within the second target film thickness distribution range, causing a pressure regulation device to perform an operation of changing a pressure of a fluid supplied to the pressure chamber.

The substrate holding device can eliminate variations in the film thickness of the substrate by operating the offset mechanism that offsets the carrier coupled to the elastic membrane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing one embodiment of a substrate processing apparatus;

FIG. 2A is a horizontal cross-sectional view (cross-sectional view taken along line C-C) of a polishing head, FIG. 2B is a vertical cross-sectional view (cross-sectional view taken along line A-A) of the polishing head, and FIG. 2C is a vertical cross-sectional view (cross-sectional view taken along line B-B) of the polishing head;

FIG. 3A is a plan view showing a retaining ring and a spacer, FIG. 3B is a cross-sectional view taken along line X-X in FIG. 3A, and FIG. 3C is a cross-sectional view taken along line Y-Y in FIG. 3A;

FIG. 4 is a view showing an elastic membrane forming a pressure chamber and a carrier coupled to the elastic membrane;

FIG. 5 is a view showing a rotational torque transmission mechanism;

FIG. 6 is a view showing a tilting structure;

FIG. 7 is a plan view of an offset mechanism;

FIG. 8A is a view showing the carrier in a non-eccentric state, FIG. 8B is a view showing the carrier in an eccentric state, and FIG. 8C is a view showing an eccentricity (amount of eccentricity) of the carrier;

FIGS. 9A and 9B are views showing a difference in a pressing force acting on a peripheral portion of a wafer;

FIG. 10A is a view showing a uniform gap formed between the retaining ring and the carrier, and FIG. 10B is a view showing a non-uniform gap formed between the retaining ring and the carrier;

FIG. 11 is a view showing one embodiment of a polishing flow of the wafer incorporating an operation of the offset mechanism;

FIG. 12 is a view showing an example of information associated with a film thickness distribution of the wafer when determining an eccentricity direction and an eccentricity of the carrier;

FIG. 13 is a view showing another embodiment of the polishing flow of the wafer;

FIG. 14 is a view showing another embodiment of the polishing flow of the wafer;

FIG. 15 is a view showing a reference position of an angle of the circumferential direction of the wafer;

FIGS. 16A to 16C are views showing another embodiment of the offset mechanism; and

FIG. 17A is a view showing the carrier in a non-eccentric state, FIG. 17B is a view showing the carrier in an eccentric state, and FIG. 17C is a view showing the eccentricity of the carrier.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and duplicated descriptions will be omitted. In the multiple embodiments described below, the configuration of one embodiment that is not particularly described is the same as the other embodiments, so duplicated descriptions will be omitted.

FIG. 1 is a view showing one embodiment of a substrate processing apparatus. As shown in FIG. 1, the substrate processing apparatus (more specifically, a polishing apparatus) 1 includes a substrate holding device (polishing head) 10 that holds and rotates a wafer W, which is an example of a substrate, a polishing table 2 that supports a polishing pad 5, and a polishing liquid supply nozzle 19 that supplies a polishing liquid (slurry) onto the polishing pad 5.

The polishing head 10 is configured to hold the wafer W on its lower surface by vacuum suction. The polishing head 10 and the polishing table 2 rotate in the same direction, and in this state, the polishing head 10 presses the wafer W against a polishing surface 5a of the polishing pad 5. The polishing liquid supply nozzle 19 supplies the polishing liquid onto the polishing pad 5. The wafer W comes into sliding contact with the polishing pad 5 in the presence of the polishing liquid, and is polished by a combined effect of a chemical action of chemical components of the polishing liquid and a mechanical action of abrasive grains contained in the polishing liquid.

The substrate processing apparatus 1 includes a head shaft 12 coupled to a polishing head 10, a head arm 13 coupled to the head shaft 12, and an arm shaft 14 supporting the head arm 13 so that it can swing freely.

The head shaft 12 is configured to move up and down relative to the head arm 13 by a vertical movement mechanism (not shown). The head arm 13 is configured to swivel about the arm shaft 14 by a swivel mechanism (not shown). The polishing head 10 holding the wafer W moves between a transfer position (a position outside the polishing table 2) for the wafer W and a position above the polishing table 2 by swiveling the head arm 13.

The substrate processing apparatus 1 includes a head motor 15 that rotates the head shaft 12. The head motor 15 is built into the head arm 13. When the head motor 15 is driven, the polishing head 10 rotates together with the head shaft 12. The substrate processing apparatus 1 includes a rotation angle measurement device 50A coupled to the head motor 15. The rotation angle measurement device 50A is configured to measure a rotation angle of the polishing head 10. The rotation angle measurement device 50A may include a rotary encoder.

The polishing table 2 is supported by a table shaft 3. The table shaft 3 is coupled to a table motor 4. When the table motor 4 is driven, the polishing table 2 (and the polishing pad 5) rotates together with the table shaft 3. The substrate processing apparatus 1 includes a rotation angle measurement device 50B coupled to the table motor 4. The rotation angle measurement device 50B is configured to measure a rotation angle of the polishing table 2. The rotation angle measurement device 50B may include a rotary encoder.

FIG. 2A is a horizontal cross-sectional view (cross-sectional view taken along line C-C) of the polishing head, FIG. 2B is a vertical cross-sectional view (cross-sectional view taken along line A-A) of the polishing head, and FIG. 2C is a vertical cross-sectional view (cross-sectional view taken along line B-B) of the polishing head.

As shown in FIGS. 2A to 2C, the polishing head 10 includes a head main body 20.

The head main body 20 includes a circular housing (or flange) 21 connected to the head shaft 12, a spacer 75 attached to a lower surface of the housing 21, a carrier 71 arranged below the spacer 75, and a retaining ring 70 arranged on a side of the carrier 71.

FIG. 3A is a plan view showing the retaining ring and the spacer, FIG. 3B is a cross-sectional view taken along line X-X in FIG. 3A, and FIG. 3C is a cross-sectional view taken along line Y-Y in FIG. 3A. In FIGS. 3B and 3C, the housing 21 and the carrier 71 are omitted.

The retaining ring 70 includes a ring portion 70a that contacts the polishing surface 5a of the polishing pad 5, and a drive ring 70b fixed to an upper portion of the ring portion 70a. The ring portion 70a surrounds a peripheral portion of the wafer W and holds the wafer W so that the wafer W does not jump out of the polishing head 10 during polishing the wafer W.

The drive ring 70b of the retaining ring 70 has a plurality (six in the embodiment shown in FIG. 3) of spokes 70d extending radially from a shaft portion 70c (described later) arranged at a center portion of the drive ring 70b. The spacer 75 has a plurality of radial grooves 75a in which the plurality of spokes 70d are accommodated.

A small gap is formed between the groove 75a of the spacer 75 and the spokes 70d of the drive ring 70b. Therefore, the retaining ring 70 moves up and down and tilts relative to the spacer 75. When the housing 21 (and the head shaft 12) is rotated by driving the head motor 15, the rotational torque acting on the housing 21 is transmitted to the retaining ring 70 via the spacer 75.

FIG. 4 is a view showing an elastic membrane forming a pressure chamber and a carrier coupled to the elastic membrane. As shown in FIG. 4, the polishing head 10 includes an elastic membrane 72 forming at least one (eight in this embodiment) pressure chamber 77a, 77b, 77c, 77d, 77e, 77f, 77g, 77h for pressing the wafer W. The elastic membrane 72 is made of a flexible rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber.

The elastic membrane 72 has a plurality of (eight in this embodiment) annular peripheral walls 78a, 78b, 78c, 78d, 78e, 78f, 78g, and 78h. These peripheral walls 78a to 78h are concentrically arranged and coupled to the carrier 71.

A lower surface of the carrier 71 and the peripheral walls 78a to 78h form the pressure chambers 77a to 77h arranged below the carrier 71. The pressure chambers 77a to 77g have an annular shape, and the pressure chamber 77h has a circular shape. The pressure chambers 77a to 77h are arranged concentrically.

The elastic membrane 72 has a side wall 72a arranged on a side of the carrier 71. The side wall 72a is arranged concentrically with the peripheral walls 78a to 78h. One end of the side wall 72a is coupled to the retaining ring 70, and the other end is coupled to the carrier 71.

As shown in FIG. 4, the substrate processing apparatus 1 includes a fluid line 79a coupled to each of the pressure chambers 77a to 77h. The fluid line 79a is coupled to the pressure regulation device 16 via a rotary joint (not shown). More specifically, the fluid line 79a passes through a through hole 74 (see FIGS. 3A and 3C) formed in the spacer 75 and communication holes formed in the housing 21 and the head shaft 12, and is coupled to the pressure regulation device 16.

The pressure regulation device 16 is configured to adjust the pressure inside each of the pressure chambers 77a to 77h independently. The pressure regulation device 16 may include an electro-pneumatic regulator. Although not shown, each of the pressure chambers 77a to 77h is configured to create a positive pressure or a negative pressure therein. Furthermore, the pressure chambers 77a to 77h can be opened to an atmosphere.

The polishing head 10 includes an annular rolling diaphragm 86 arranged between the housing 21 and the drive ring 70b (see FIGS. 2B and 2C). The substrate processing apparatus 1 includes a fluid line 79b coupled to the rolling diaphragm 86. The fluid line 79b, like the fluid line 79a, is coupled to the pressure regulation device 16 via a rotary joint. The pressure regulation device 16 is configured to independently regulate the pressure inside the rolling diaphragm 86.

FIG. 5 is a view showing a rotational torque transmission mechanism. As shown in FIG. 5 (and FIGS. 2A and 2C), the polishing head 10 includes a rotational torque transmission mechanism 85 that transmits a rotational torque acting on the retaining ring 70 to the carrier 71.

When the head motor 15 is driven, the retaining ring 70 rotates together with the housing 21. The rotational torque transmission mechanism 85 is configured to transmit the rotational torque acting on the retaining ring 70 to the carrier 71. The rotational torque transmission mechanism 85 includes a plurality of protrusions 85a extending from the drive ring 70b of the retaining ring 70 toward the carrier 71, and a fitting portion 85b into which each of the protrusions 85a fits loosely.

The protrusions 85a are fixed to the inner peripheral surface of the drive ring 70b arranged radially outward of the carrier 71. The fitting portions 85b are formed on an outer peripheral surface of the carrier 71 arranged radially inward of the drive ring 70b.

Since the fitting portion 85b has a size larger than the projection 85a, the projection 85a fits loosely into the fitting portion 85b. In the embodiment shown in FIG. 2A, three projections 85a are arranged at equal intervals along the circumferential direction of the drive ring 70b, but the number of projections 85a is not limited to this embodiment.

As each protrusion 85a fits into each fitting portion 85b, the rotational torque transmission mechanism 85 transmits the rotational torque acting on the retaining ring 70 to the carrier 71, and the carrier 71 rotates together with the retaining ring 70.

The rotational torque transmission mechanism 85 not only transmits the rotational torque acting on the retaining ring 70 to the carrier 71, but also holds the carrier 71 to the retaining ring 70. Therefore, even if the polishing head 10 rises together with the head shaft 12 and gravity acts on the carrier 71, the carrier 71 will not fall off the retaining ring 70. In this manner, the rotational torque transmission mechanism 85 applies a rotational force to the carrier 71 while preventing the carrier 71 from falling off the retaining ring 70.

FIG. 6 is a view showing a tilting structure. As shown in FIG. 6, the polishing head 10 includes a tilting structure 76 that tilts the retaining ring 70. The tilting structure 76 is arranged in an accommodation recess 71a formed in a center portion of the carrier 71.

The retaining ring 70 surrounding the carrier 71 has a shaft portion 70c extending from a lower surface of the drive ring 70b toward the accommodation recess 71a of the carrier 71. The shaft portion 70c is formed at the center of the drive ring 70b and extends along the central axis CL1 of the head shaft 12. The shaft portion 70c extends into the accommodation recess 71a.

In the embodiment shown in FIG. 6, the tilting structure 76 includes a spherical bearing mounted on the shaft portion 70c of the retaining ring 70. The tilting structure 76 as a spherical bearing includes an annular inner ring 76a and an outer ring 76b that slidably supports an outer circumferential surface of the inner ring 76a.

The spacer 75 has an annular protrusion 73 extending toward the accommodation recess 71a. The annular protrusion 73 is arranged radially outward of the shaft portion 70c of the retaining ring 70, and the tilting structure 76 is arranged between the shaft portion 70c and the annular protrusion 73.

The outer ring 76b is fixed to an inner peripheral surface of the annular projection 73 and slidably supports the inner ring 76a. Therefore, the inner ring 76a can tilt in all directions (360 degrees) relative to the outer ring 76b. The shaft portion 70c is inserted into the inner ring 76a. Therefore, the retaining ring 70 including the shaft portion 70c can move only vertically relative to the inner ring 76a, while a horizontal movement of the retaining ring 70 is limited by the tilting structure 76. With this configuration, the retaining ring 70 is configured to be vertically movable and tiltable independently of the head main body 20.

FIG. 7 is a plan view of an offset mechanism. As shown in FIGS. 6 and 7, the polishing head 10 includes an offset mechanism 80 that offsets the carrier 71 with respect to the retaining ring 70. In this embodiment, the offset mechanism 80 is arranged in the accommodation recess 71a of the carrier 71. The offset mechanism 80 includes a plurality of pressing actuators 81 that are arranged at equal intervals along the circumferential direction of the retaining ring 70.

The pressing actuators 81 have the same structure and are configured to apply a pressing force to the spokes 70d in a direction parallel to an extension direction of the spokes 70d (i.e., a direction perpendicular to a central axis line CL1).

The pressing actuator 81 may include a ball screw mechanisms including a motor and a ball screw, or an air cylinder. In one embodiment, the pressing actuator 81 may include a combination of the ball screw mechanism and the air cylinder.

The pressing actuators 81 are arranged at equal intervals along the circumferential direction of the annular protrusion 73. In this embodiment, three pressing actuators 81 are arranged, but the number of pressing actuators 81 is not limited to this embodiment.

The pressing actuator 81 includes a pressing member 81a that applies a pressing force to the head main body 20 (more specifically, the annular protrusion 73 of the spacer 75) and a holding member 81b that holds the pressing member 81a. The holding member 81b is embedded in an inner circumferential surface of the accommodation recess 71a of the carrier 71. The pressing member 81a extends from the holding member 81b toward the annular protrusion 73 and is configured to be freely expandable and contractible.

Each pressing actuator 81 expands or contracts the pressing member 81a by driving the pressing actuator 81. When the pressing member 81a expands, the pressing force is applied to the annular protrusion 73. The spacer 75 including the annular protrusion 73 is fixed to the head shaft 12 via the housing 21. Therefore, the pressing force applied to the annular protrusion 73 acts on the carrier 71 to which the pressing actuator 81 is attached.

Since the protrusion 85a of the rotational torque transmission mechanism 85 is loosely fitted into the fitting portion 85b, the carrier 71 is movable relative to the retaining ring 70. Therefore, each pressing actuator 81 applies the pressing force applied to the annular protrusion 73 to the carrier 71. In other words, each pressing actuator 81 indirectly applies the pressing force to the carrier 71.

FIG. 8A is a view showing the carrier in a non-eccentric state, FIG. 8B is a view showing the carrier in an eccentric state, and FIG. 8C is a view showing an eccentricity (amount of eccentricity) of the carrier. The carrier 71 moves relative to the retaining ring 70 depending on a magnitude of the pressing force applied to the annular protrusion 73 and a pressing direction against the annular protrusion 73.

In FIG. 8A, the central axis CL1 of the retaining ring 70 (i.e., the head main body 20) and the central axis CL2 of the carrier 71 are aligned with each other. In this manner, the position where the central axes CL1 and CL2 are aligned with each other is an initial position of the carrier 71. In other words, the initial position of the carrier 71 is a position when displacements (amounts of displacement) of all the pressing actuators 81 are at their initial values.

By operating each pressing actuator 81, the carrier 71 (i.e., the central axis CL2) becomes eccentric with respect to the central axis CL1 of the retaining ring 70. The eccentric direction and the eccentricity of the carrier 71 depend on the pressing direction and the magnitude of the pressing force of each pressing actuator 81. In FIGS. 8B and 8C, by extending one of the three pressing actuators 81 and contracting the two push actuators 81, the center axis CL2 of the carrier 71 is displaced from the center axis CL1 by the eccentricity (displacement) d.

FIGS. 9A and 9B are views showing a difference in the pressing force acting on the peripheral portion of the wafer. As shown in FIG. 9A, when a sufficient gap is formed between the carrier 71 and the retaining ring 70 (i.e., when the gap is large), the elastic membrane 72 forming the pressure chamber 77a does not contact the ring portion 70a of the retaining ring 70.

In the embodiment shown in FIG. 9A, the carrier 71 is arranged at the initial position, and a uniform gap is formed between the retaining ring 70 and the elastic membrane 72 in the circumferential direction of the wafer W. In this case, the expansion force of the elastic membrane 72 is dispersed into a force acting on the side wall 72a side and a force acting on the wafer W side. Therefore, the pressing force of the wafer W against the polishing surface 5a by the elastic membrane 72 is small, and as a result, a polishing rate at the peripheral portion of the wafer W is almost the same as (or slightly smaller than) the polishing rate inside the peripheral portion of the wafer W.

On the other hand, as shown in FIG. 9B, when there is no sufficient gap between the carrier 71 and the retaining ring 70 (i.e., when the gap is small), the elastic membrane 72 that forms the pressure chamber 77a comes into contact with the ring portion 70a of the retaining ring 70. An area where the elastic membrane 72 comes into contact with the ring portion 70a is called a contact area 72b.

In this case, the expansion force of the elastic membrane 72 acts largely on the wafer W. Therefore, the pressing force of the wafer W against the polishing surface 5a by the elastic film 72 is large, and as a result, the polishing rate at the peripheral portion of the wafer W is greater than a polishing rate on the inner side of the peripheral portion of the wafer W.

The offset mechanism 80 is configured to offset (displace or move) the carrier 71 to form a non-uniform gap between the retaining ring 70 and the elastic membrane 72 in the circumferential direction of the wafer W. Therefore, even if the film thickness varies along the circumferential direction of the wafer W, the offset mechanism 80 can offset the carrier 71 to control the polishing rate for each of a plurality of areas on the peripheral portion of the wafer W, thereby polishing the wafer W non-uniformly in the circumferential direction of the wafer W. In this manner, the offset mechanism 80 can eliminate the variation in the film thickness on the peripheral portion of the wafer W.

In one embodiment, when the offset mechanism 80 offsets the carrier 71, the elastic membrane 72 may have a coating material SR1 with good slipperiness applied to its surface so that the elastic membrane 72 moves smoothly over the wafer W (see FIGS. 9A and 9B). The coating material SR1 faces a back surface of the wafer W. The coating material SR1 may include a polytetrafluoroethylene (PTFE) coating.

The carrier 71 has a facing surface facing the spacer 75. In one embodiment, the carrier 71 may have a coating material SR2 with good slipperiness applied to its facing surface (see FIG. 6). The coating material SR2 may include a polytetrafluoroethylene (PTFE) coating.

FIG. 10A is a view showing a uniform gap formed between the retaining ring and the carrier, and FIG. 10B is a view showing a non-uniform gap formed between the retaining ring and the carrier. In FIGS. 10A and 10B, the film thickness in an area AR at the peripheral portion of the wafer W is large. In FIG. 10A, when the carrier 71 is not offset (decentered or moved) by the offset mechanism 80, the gap between the retaining ring 70 and the carrier 71 is uniform (i.e., gap A=gap B).

As described with reference to FIG. 9B, the offset mechanism 80 can increase the polishing rate of a specific region in the circumferential direction of the wafer W by offsetting the carrier 71. As shown in FIG. 10B, the area AR of the wafer W corresponds to a position where the polishing head angle is 0 degrees. Note that the area indicated by the thick black dotted line in FIG. 10B represents the contact area 72b of the elastic membrane 72 with the retaining ring 70.

Therefore, when the film thickness in the area AR is large, the offset mechanism 80 offsets (decenters or moves) the carrier 71 to a position where the polishing head angle is 0 degrees (i.e., gap A>gap B). The polishing rate of the wafer W depends on the eccentricity of the carrier 71. Therefore, the eccentricity of the carrier 71 is appropriately determined according to the film thickness in the area AR. As a result, the polishing rate in the area AR becomes higher than the polishing rates in other areas, and the area AR is actively polished. In this manner, the film thickness in the area AR can be reduced.

The offset mechanism 80 is configured to offset the carrier 71 based on the measured film thickness of the wafer W during polishing the wafer W. More specifically, as shown in FIG. 1, the substrate processing apparatus 1 includes a film thickness sensor 30 that detects a film thickness signal that changes according to the film thickness of the wafer W, and a control device 60 that measures the film thickness of the wafer W based on the film thickness signal detected by the film thickness sensor 30.

The film thickness sensor 30 is arranged inside the polishing table 2. Every time the polishing table 2 rotates once, the film thickness sensor 30 detects (generates) film thickness signals in a plurality of areas including the central portion of the wafer W. The film thickness sensor 30 may include an optical sensor or an eddy current sensor.

The control device 60 is electrically connected to components (e.g., the film thickness sensor 30, the rotation angle measurement devices 50A and 50B, etc.) of the substrate processing apparatus 1. The control device 60 obtains information such as a film thickness signal detected by the film thickness sensor 30, the rotation angle of the polishing head 10 measured by the rotation angle measurement device 50A, and the rotation angle of the polishing table 2 measured by the rotation angle measurement device 50B.

The control device 60 is configured to control operations of the substrate processing apparatus 1 including the operation of the offset mechanism 80 (e.g., operations of the polishing head 10, the polishing table 2, and the polishing liquid supply nozzle 19). In this embodiment, the control device 60 is configured by a computer.

As shown in FIG. 1, the control device 60 includes a memory unit 60D in which programs, data, etc. are stored, a measurement unit 60C that measures the film thickness of the wafer W based on the film thickness signal obtained from the film thickness sensor 30, a calculation unit 60B such as a CPU (central processing unit) or GPU (graphic processing unit) that performs calculations in accordance with the programs stored in the memory unit 60D, and a control unit 60A that controls the operation of the substrate processing apparatus 1 based on results calculated by the calculation unit 60B.

FIG. 11 is a view showing one embodiment of a polishing flow of the wafer incorporating the operation of the offset mechanism. The control device 60 is configured to perform each step described with reference to FIG. 11. When polishing of the wafer W is started, the film thickness sensor 30 rotates together with the polishing table 2 and detects the film thickness signal while crossing the surface of the wafer W. The film thickness signal is an index value that directly or indirectly indicates the film thickness, and changes as the film thickness of the wafer W decreases.

During polishing of the wafer W, the film thickness sensor 30 detects a plurality of film thickness signals by crossing the surface of the wafer W a plurality of times. As shown in step S101 of FIG. 11, the measurement unit 60C measures the film thickness distribution on the wafer W based on the plurality of film thickness signals detected by the film thickness sensor 30.

The memory unit 60D stores the film thickness distribution of the wafer W measured by the measurement unit 60C. Thereafter, the calculation unit 60B determines the eccentricity direction and the eccentricity of the carrier 71 based on the film thickness distribution of the wafer W measured during polishing of the wafer W, and calculates the displacements of the three pressing actuators 81 based on the determined eccentricity direction and the eccentricity (step S102).

FIG. 12 is a view showing an example of information associated with the film thickness distribution of the wafer when determining the eccentricity direction and the eccentricity of the carrier. The calculation unit 60B determines the eccentricity direction and the eccentricity of the carrier 71 by associating information on the film thickness distribution of the wafer W with the following information (1) to (5).

• • (1) A distance R1 of the central axis CL1 of the polishing head 10 from a rotation center CL3 of the polishing table 2
  • (2) A rotation angle RA1 of a position where the central axis CL1 of the polishing head 10 on the polishing table 2 is arranged
  • (3) A rotation angle RA1 of a position where the film thickness sensor 30 on the polishing table 2 is arranged
  • (4) A rotation angle RA2 of the polishing head 10
  • (5) A distance R2 of the film thickness sensor 30 from the rotation center CL3

When the polishing head 10 is oscillated during polishing of the wafer W, the calculation unit 60B may associate information on an oscillation angle of the polishing head 10 with information on the film thickness distribution of the wafer W.

The rotation angle RA1 indicates the rotation angle of the polishing table 2 measured based on the rotation angle measurement device 50B (see FIG. 1) coupled to the table motor 4, and the rotation angle RA2 indicates the rotation angle of the polishing head 10 measured based on the rotation angle measurement device 50A (see FIG. 1) coupled to the head motor 15.

When the rotation angle of the initial position of the film thickness sensor 30 (approximately 190 degrees in the embodiment shown in FIG. 12) is represented as a RA1, the rotation angle RA1′ represents a deviation in a rotation phase between a starting point (i.e., zero degrees) of the rotation phase of the rotation angle measurement device 50B and the position of the film thickness sensor 30. During polishing of the wafer W, the current rotation angle of the film thickness sensor 30 changes with the rotation of the polishing table 2. Therefore, the rotation angle RA1 when measuring the current rotation angle of the film thickness sensor 30 is calculated as the rotation angle obtained by adding the rotation angle RA1′ of the initial position of the film thickness sensor 30.

When the rotation angle of the initial position of the polishing head 10 (approximately 260 degrees in the embodiment shown in FIG. 12) is expressed as a RA1″, the rotation angle RA1″ represents a deviation in a rotation phase between the starting point (i.e., zero degrees) of the rotation phase of the rotation angle measurement device 50B and the position of the polishing head 10. During polishing of the wafer W, the rotation angle of the polishing head 10 does not change with the rotation of the polishing table 2. Therefore, the rotation angle RA1 when measuring the current rotation angle of the polishing head 10 corresponds to the rotation angle RA1″.

The above-described information (1) to (5) is stored in the memory unit 60D. These are examples of information associated with the film thickness distribution of the wafer W, and it is not necessary to associate all of the information (1) to (5) with the film thickness distribution of the wafer W. At least one of the information (1) to (5) may be associated with the film thickness distribution of the wafer W.

After step S102, the control unit 60A receives an instruction from the calculation unit 60B and operates at least one of the three pressing actuators 81 to offset the carrier 71 (see step S103). In this manner, the offset mechanism 80 forms a non-uniform gap between the retaining ring 70 and the elastic membrane 72 in the circumferential direction of the wafer W.

Thereafter, the wafer W is polished for a predetermined time (see step S104), and the measurement unit 60C again measures the film thickness distribution on the wafer W based on the film thickness signals detected by the film thickness sensor 30 (see step S105).

The calculation unit 60B determines whether or not the current average film thickness over the entire wafer W (i.e., in the circumferential and radial directions) is equal to or less than a predetermined target value based on the film thickness distribution of the wafer W measured in step S105 (see step S106). If the current average film thickness is equal to or less than the target value (see “YES” in step S106), the calculation unit 60B determines a polishing end point of the wafer W and finishes polishing of the wafer W.

On the other hand, if the current average film thickness is not equal to or less than the target value (see “NO” in step S106), the calculation unit 60B determines whether the current film thickness distribution in the circumferential direction of the wafer W is within a range of a predetermined target film thickness distribution (first target film thickness distribution) (see step S107).

If the current film thickness distribution is within a first target film thickness distribution range (see “YES” in step S107), the control unit 60A returns the displacements of all the pressing actuators 81 to their initial values (i.e., initial positions) (see step S108). More specifically, the control unit 60A operates all the pressing actuators 81 so that the central axis CL1 of the retaining ring 70 and the central axis CL2 of the carrier 71 coincide with each other.

In this manner, the polishing head 10 forms a uniform gap between the retaining ring 70 and the elastic membrane 72 in the circumferential direction of the wafer W, thereby uniformly polishing the wafer W. After step S108, the control device 60 performs the same step as step S104.

If the current film thickness distribution is not within the first target film thickness distribution range (see “NO” in step S107), the calculation unit 60B performs an operation of checking whether the eccentricity direction and the eccentricity of the carrier 71 coincide (correspond) to the film thickness distribution of the wafer W (see step S109). If the eccentricity direction and the eccentricity of the carrier 71 coincide to the film thickness distribution of the wafer W (see “YES” in step S109), the control device 60 performs the same step as step S104.

On the other hand, if the eccentricity direction and the eccentricity of the carrier 71 do not coincide the film thickness distribution of the wafer W (see “NO” in step S109), the control device 60 performs the same step as step S102. More specifically, the calculation unit 60B again determines the eccentricity direction and the eccentricity of the carrier 71, and calculates the displacements of the three pressing actuators 81 based on the determined eccentricity direction and the eccentricity.

In the flowchart shown in FIG. 11, the calculation unit 60B determines whether or not the current film thickness distribution in the circumferential direction of the wafer W is within the first target film thickness distribution range (see step S107), but in one embodiment, the calculation unit 60B may determine whether or not the current film thickness distribution in the radial direction of the wafer W is within the range of a predetermined target film thickness distribution (second target film thickness distribution).

FIG. 13 is a view showing another embodiment of the polishing flow of the wafer. As shown in FIG. 13, the control device 60 performs steps S201 to S206 corresponding to steps S101 to S106 in FIG. 11. After step S206, the calculation unit 60B determines whether the current film thickness distribution in the radial direction of the wafer W is within a second target film thickness distribution range (see step S207).

If the current film thickness distribution is within the second target film thickness distribution range (see “YES” in step S207), the calculation unit 60B performs step S210, which corresponds to step S107. Thereafter, the control device 60 performs step S211, which corresponds to step S108, or step S212, which corresponds to step S109, based on the result of step S210.

If the current film thickness distribution is not within the range of the second target film thickness distribution (see “NO” in step S207), the calculation unit 60B calculates the amount of pressure change of the fluid supplied to each of the pressure chambers 77a to 77h (see step S208). More specifically, the calculation unit 60B determines a pressure chamber corresponding to a specific film thickness so that the current film thickness distribution in the radial direction of the wafer W is within the second target film thickness distribution range, and calculates the amount of pressure change of the fluid supplied to the determined pressure chamber.

After step S208, the calculation unit 60B issues an instruction to the control unit 60A based on the determined amount of pressure change. In response to the instruction from the calculation unit 60B, the control unit 60A changes the output value of the pressure regulation device 16 (more specifically, each electro-pneumatic regulator) and operates the pressure regulation device 16 (see step S209). Thereafter, the calculation unit 60B performs step S210, which corresponds to step S107.

FIG. 14 is a view showing another embodiment of the polishing flow of the wafer. FIG. 15 is a view showing a reference position of an angle of the circumferential direction of the wafer. During polishing of the wafer W, the wafer W may be deviated relative to the polishing head 10 in the rotation direction of the polishing head 10 due to a frictional force acting between the wafer W and the polishing pad 5.

If the wafer W is deviated in the rotation direction of the polishing head 10, the film thickness distribution of the wafer W does not coincide with the displacement amount of the pressing actuator 81 calculated by the calculation unit 60B. As a result, the control unit 60A may not be able to accurately eliminate the variation in the film thickness of the wafer W.

Therefore, the substrate processing apparatus 1 includes a reference position detection device 40 that detects the reference position of the angle of the circumferential direction of the wafer W during polishing of the wafer W (see FIG. 1). In this embodiment, the reference position of the angle of the circumferential direction of the wafer W is a position of a notch Nt formed on the peripheral portion of the wafer W (see FIG. 15).

As shown in FIG. 1, the reference position detection device 40 is arranged adjacent to the polishing head 10. The reference position detection device 40 may include a fiberscope. The reference position detection device 40 constantly monitors the position of the notch Nt of the wafer W during polishing of the wafer W.

The control device 60 (more specifically, the calculation unit 60B) is electrically connected to the reference position detection device 40 and is configured to obtain the position of the notch Nt from the reference position detection device 40 during polishing of the wafer W.

The control device 60 calculates the relative angle of the position of the notch Nt with respect to the polishing head 10 based on a first signal (first data) regarding the rotation angle of the polishing head 10 obtained from the rotation angle measurement device 50A and a second signal (second data) regarding the position of the notch Nt obtained from the reference position detection device 40.

Based on the rotation angle of the polishing head 10 obtained from the rotation angle measurement device 50A, the control device 60 determines a relative angle between the position of the notch Nt and the polishing head 10 before polishing of the wafer W starts. After polishing of the wafer W starts, the measurement unit 60C measures the film thickness distribution on the wafer W based on the film thickness signals detected by the film thickness sensor 30 (see step S301).

At this time, the control device 60 (more specifically, the calculation unit 60B) starts polishing the wafer W, and identifies the position of the notch Nt based on the data obtained from the reference position detection device 40 during polishing of the wafer W.

The calculation unit 60B checks whether a positional relationship (i.e., the current relative angle) between the circumferential direction of the wafer W and the circumferential direction of the polishing head 10 at the time of measuring the film thickness distribution of the wafer W has changed compared to the relative angle before the start of polishing of the wafer W (see step S302). If the current relative angle has not changed (see “NO” in step S303), the control device 60 performs steps S305 to S312, which correspond to steps S102 to S109.

On the other hand, if the current relative angle has changed (see “YES” in step S303), the calculation unit 60B calculates the amount of change in the current relative angle, and corrects the film thickness distribution of the wafer W based on the calculated amount of change in the relative angle (see step S304).

More specifically, the calculation unit 60B corrects the relative angle to synchronize the positional relationship of the film thickness distribution of the wafer W with the eccentricity direction and the eccentricity of the pressing actuator 81. Thereafter, the control device 60 performs steps S305 to S312. According to this embodiment, even if the wafer W is deviated in the rotation direction of the polishing head 10, the control unit 60A can eliminate the variation in the film thickness of the wafer W.

The control device 60 performs each of the above-described steps according to instructions included in the program stored in the memory unit 60D. The program for causing the control device 60 to perform each of the above-described steps is recorded in a computer-readable storage medium, which is a non-transitory tangible object, and is provided to the control device 60 via the storage medium. Alternatively, the program may be input to the control device 60 via a communication network such as the Internet or a local area network.

FIGS. 16A to 16C are views showing another embodiment of the offset mechanism. In the embodiment shown in FIGS. 16A to 16C, configurations that are not specifically described are the same as those in the above-described embodiment, and therefore redundant description will be omitted.

FIG. 16A is a horizontal cross-sectional view (cross-sectional view taken along line C-C) of the polishing head, FIG. 16B is a vertical cross-sectional view (cross-sectional view taken along line A-A) of the polishing head, and FIG. 16C is a vertical cross-sectional view (cross-sectional view taken along line B-B) of the polishing head.

In the embodiments shown in FIGS. 16A to 16C, the head main body 20 does not include the spacer 75, and the drive ring 70b and the housing 21 are integrally configured. In other words, the drive ring 70b and the housing 21 are the same structure.

The head shaft 12 is coupled to the drive ring 70b (i.e., the housing 21) via a tilting structure 96. In this embodiment, the tilting structure 96 is a ball joint. The drive ring 70b (i.e., the housing 21) is tiltable with respect to the head shaft 12 by the tilting structure 96.

The carrier 71 is arranged below the drive ring 70b. In this embodiment, the carrier 71 may have the coating material SR2 applied to the facing surface facing the drive ring 70b (see FIG. 6). Similarly, the elastic membrane 72 may have the coating material SR1 with good slipperiness applied to its surface (see FIGS. 9A and 9B).

As shown in FIGS. 16A to 16C, the polishing head 10 may include an offset mechanism 90 instead of the offset mechanism 80. The offset mechanism 90 includes a plurality of pressing actuators 91 that directly apply a pressing force to the carrier 71.

The pressing actuators 91 have the same structure. Each pressing actuator 91 is configured to apply the pressing force to the carrier 71 in a direction perpendicular to the central axis line CL1. The pressing actuator 91 may include a ball screw mechanism including a motor and a ball screw, or an air cylinder. In one embodiment, the pressing actuator 91 may be a combination of a ball screw mechanism and an air cylinder.

The pressing actuators 91 are arranged at equal intervals along the circumferential direction of the retaining ring 70 and are supported by the retaining ring 70. More specifically, the retaining ring 70 has a plurality of housing insertion portions 95 that are arranged at equal intervals along the circumferential direction of the retaining ring 70.

Each of the pressing actuators 91 is accommodated in a corresponding one of the housing insertion portions 95. In this embodiment, three pressing actuators 91 are arranged, but the number of pressing actuators 91 is not limited to this embodiment.

The pressing actuator 91 includes a pressing member 91a that applies a pressing force to the carrier 71, and a holding member 91b that holds the pressing member 91a. The housing insertion portion 95 has an insertion hole 95a that extends in the radial direction of the retainer ring 70, and a recessed portion 95b connected to the insertion hole 95a. The pressing member 91a is inserted into the insertion hole 95a, and the holding member 91b is placed in the recessed portion 95b.

The pressing member 91a extends from the holding member 91b toward the carrier 71 and is configured to be freely expandable and contractible. Each pressing actuator 91 expands or contracts the pressing member 91a by driving the pressing actuator 91. When the pressing member 91a expands, it applies the pressing force to the carrier 71.

FIG. 17A is a view showing the carrier in a non-eccentric state, FIG. 17B is a view showing the carrier in an eccentric state, and FIG. 17C is a view showing the eccentricity of the carrier. The carrier 71 moves relative to the retaining ring 70 in accordance with a magnitude of the pressing force and a pressing direction applied by the pressing actuator 91.

In FIG. 17A, the central axis CL1 of the retaining ring 70 (i.e., the head main body 20) and the central axis CL2 of the carrier 71 are aligned with each other. On the other hand, by operating each pressing actuator 91, the central axis CL2 of the carrier 71 becomes eccentric with respect to the central axis CL1 of the retaining ring 70.

The eccentricity direction and the eccentricity of the carrier 71 depend on the pressing direction and the magnitude of the pressing force of each pressing actuator 91. In FIGS. 17B and 17C, two pressing actuators 91 are expanded and one pressing actuator 91 is contracted of the three pressing actuators 91, so that the central axis CL2 of the carrier 71 is displaced from the central axis CL1 by the eccentricity (the amount of displacement) d.

In this embodiment as well, the offset mechanism 90 is configured to offset (displace or move) the carrier 71 to form a non-uniform gap between the retaining ring 70 and the elastic membrane 72 in the circumferential direction of the wafer W. Therefore, even if there is variation in the film thickness along the circumferential direction of the wafer W, the offset mechanism 90 can eliminate the variation in the film thickness at the peripheral portion of the wafer W.

In one embodiment, the embodiments shown in FIGS. 1 to 15 may be combined with the embodiments shown in FIG. 16. More specifically, the polishing head 10 may include a combination of the offset mechanism 80 and the offset mechanism 90.

The previous description of embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the embodiments described herein but is to be accorded the widest scope as defined by limitation of the claims.

Claims

1. A substrate holding device, comprising: an elastic membrane configured to form at least one pressure chamber for pressing a substrate;a carrier coupled to the elastic membrane;a retaining ring surrounding the carrier; andan offset mechanism configured to offset the carrier relative to the retaining ring.

2. The substrate holding device according to claim 1, wherein the substrate holding device comprises a tilting structure configured to tilt the retaining ring.

3. The substrate holding device according to claim 2, wherein the tilting structure is arranged in an accommodation recess of the carrier and comprises a spherical bearing mounted on a shaft portion of the retaining ring.

4. The substrate holding device according to claim 2, wherein the tilting structure comprises a ball joint coupling the retaining ring and a head shaft.

5. The substrate holding device according to claim 1, wherein the offset mechanism comprises a plurality of pressing actuators supported by the carrier, and wherein each of the pressing actuators applies a pressing force to the carrier.

6. The substrate holding device according to claim 1, wherein the offset mechanism comprises a plurality of pressing actuators supported by the retaining ring and configured to apply a pressing force to the carrier.

7. The substrate holding device according to claim 1, wherein the substrate holding device comprises a rotational torque transmission mechanism configured to transmit a rotational torque acting on the retaining ring to the carrier.

8. A substrate processing apparatus, comprising: a substrate holding device according to claim 1;a polishing table configured to support a polishing pad having a polishing surface against which a substrate held by the substrate holding device is pressed; anda control device configured to control an operation of the substrate holding device,wherein the control device is configured to: determine an eccentricity direction and an eccentricity of a carrier based on a film thickness distribution of the substrate measured during polishing of the substrate; andoperate an offset mechanism to offset the carrier based on the determined eccentricity direction and eccentricity.

9. The substrate processing apparatus according to claim 8, wherein the control device is configured to: determine whether or not a relative angle of the substrate to the substrate holding device has changed when measuring the film thickness distribution of the substrate; andwhen the relative angle has changed, correct the relative angle based on the amount of change in the relative angle to determine the eccentricity direction and the eccentricity of the carrier.

10. The substrate processing apparatus according to claim 8, wherein the control device is configured to: after starting polishing of the substrate, determine whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range;when the current film thickness distribution is within the first target film thickness distribution range, operate the offset mechanism to return the carrier to an initial position; andwhen the current film thickness distribution is not within the first target film thickness distribution range, check whether the eccentricity direction and the eccentricity of the carrier correspond to the film thickness distribution of the substrate.

11. The substrate processing apparatus according to claim 8, wherein the control device is configured to: after starting polishing of the substrate, determine whether or not the current film thickness distribution in a radial direction of the substrate is within a predetermined second target film thickness distribution range;when the current film thickness distribution is within the second target film thickness distribution range, determine whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; andwhen the current film thickness distribution is not within the second target film thickness distribution range, operate a pressure regulation device to change a pressure of a fluid supplied to a pressure chamber.

12. A substrate processing method, comprising: pressing a substrate held by a substrate holding device against a polishing surface of a polishing pad to polish the substrate;determining an eccentricity direction and an eccentricity of a carrier coupled to an elastic membrane forming at least one pressure chamber for pressing the substrate based on a film thickness distribution of the substrate measured during polishing of the substrate; andoperating an offset mechanism configured to offset the carrier based on the determined eccentricity direction and eccentricity to offset the carrier.

13. The substrate processing method according to claim 12, comprising: determining whether or not a relative angle of the substrate to the substrate holding device has changed when measuring the film thickness distribution of the substrate; andwhen the relative angle has changed, correcting the relative angle based on the amount of change in the relative angle to determine the eccentricity direction and the eccentricity of the carrier.

14. The substrate processing method according to claim 12, comprising: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range;when the current film thickness distribution is within the first target film thickness distribution range, operating the offset mechanism to return the carrier to an initial position; andwhen the current film thickness distribution is not within the first target film thickness distribution range, checking whether the eccentricity direction and the eccentricity of the carrier correspond to the film thickness distribution of the substrate.

15. The substrate processing method according to claim 12, comprising: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a radial direction of the substrate is within a predetermined second target film thickness distribution range;when the current film thickness distribution is within the second target film thickness distribution range, determining whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range; andwhen the current film thickness distribution is not within the second target film thickness distribution range, operating a pressure regulation device to change a pressure of a fluid supplied to the pressure chamber.

16. A non-transitory computer-readable storage medium storing a program for causing a computer to perform the steps of: causing a substrate holding device to perform an operation of pressing a substrate against a polishing surface of a polishing pad to polish the substrate;determining an eccentricity direction and an eccentricity of a carrier coupled to an elastic membrane configured to form at least one pressure chamber for pressing the substrate based on a film thickness distribution of the substrate measured during polishing of the substrate; andcausing an offset mechanism to perform an operation of offsetting the carrier based on the determined eccentricity direction and eccentricity.

17. The storage medium according to claim 16, wherein which causes the computer to perform the steps of: determining whether or not a relative angle of the substrate with respect to the substrate holding device has changed when measuring the film thickness distribution of the substrate; andwhen the relative angle has changed, correcting the relative angle based on the amount of change in the relative angle to determine the eccentricity direction and the eccentricity of the carrier.

18. The storage medium according to claim 16, wherein which causes the computer to perform the steps of: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a circumferential direction of the substrate is within a predetermined first target film thickness distribution range;when the current film thickness distribution is within the first target film thickness distribution range, causing the offset mechanism to perform an operation of returning the carrier to an initial position; andwhen the current film thickness distribution is not within the first target film thickness distribution range, checking whether the eccentricity direction and the eccentricity of the carrier correspond to the film thickness distribution of the substrate.

19. The storage medium according to claim 16, wherein which causes the computer to perform the steps of: after starting polishing of the substrate, determining whether or not the current film thickness distribution in a radial direction of the substrate is within a predetermined second target film thickness distribution range;when the current film thickness distribution is within the second target film thickness distribution range, determining whether or not the current film thickness distribution in the circumferential direction of the substrate is within a predetermined first target film thickness distribution range; andwhen the current film thickness distribution is not within the second target film thickness distribution range, causing a pressure regulation device to perform an operation of changing a pressure of a fluid supplied to the pressure chamber.