CMP device

Abstract

Provided is a CMP device that is capable of appropriately pressing a wafer even when a condition under which a membrane film presses the wafer changes. The CMP device is provided with a polishing head that is configured to hold a wafer 15 and that polishes the wafer 15 by rotating with the wafer 15 pressed against a polishing pad 14. The polishing head is provided with: a head body that has an air chamber 46 to which pressurized air is supplied; a retainer ring 40 that has an accommodation pocket 49 accommodating the wafer 15; and a membrane film 45 that has a peripheral portion 45A held between a retainer holder 36 of the head body and the retainer ring 40, and that separates the air chamber 46 and the accommodation pocket 49 from each other. The peripheral portion 45A of the membrane film 45 is held between the retainer holder 36 and the retainer ring 40 so as to be movable in the radial direction.

Description

CMP apparatus

[0001] The present disclosure relates to a CMP apparatus for polishing wafers.

[0002] There is a CMP apparatus that polishes workpieces such as wafers by Chemical Mechanical Polishing (CMP). The CMP apparatus includes a platen having a polishing pad to whose surface slurry is supplied, and a polishing head that holds a wafer inside a retainer ring and presses the wafer against the polishing pad. For example, as disclosed in Patent Document 1, the polishing head presses and polishes the wafer using a membrane film that bends toward the polishing pad when pressurized air is supplied to an air chamber inside the polishing head. At this time, in the polishing head, the retainer ring is also pressed against the polishing pad. In recent years, polishing wafers made of difficult-to-machine materials by supplying slurry for difficult-to-machine materials onto a polishing pad has been studied. Since polishing with slurry for difficult-to-machine materials can achieve a larger polishing amount compared to polishing with ordinary slurry, the thickness of the retainer ring of the polishing head may change.

[0003] Japanese Patent Application Laid-Open No. 2024-132732

[0004] Incidentally, the state in which the membrane film presses the wafer may vary depending on factors such as the thickness of the retainer ring and the thickness of the wafer. Therefore, there is a need for a CMP apparatus that can appropriately press the wafer even when the state in which the membrane film presses the wafer changes.

[0005] A CMP apparatus that solves the above problem includes a polishing head configured to be capable of holding a wafer and polishing the wafer by rotating while pressing the wafer against a polishing pad. The polishing head includes: a head main body having an air chamber to which pressurized air is supplied; a retainer ring having an accommodation pocket for accommodating the wafer; and a membrane film having a peripheral edge portion sandwiched between the head main body and the retainer ring, the membrane film partitioning the air chamber and the accommodation pocket. The peripheral edge portion of the membrane film is sandwiched between the head main body and the retainer ring so as to be movable in a radial direction.

[0006] According to this disclosure, the wafer can be properly pressed by the membrane film.

[0007] Figure 1 is a perspective view showing a schematic configuration of one embodiment of a CMP apparatus. Figure 2 is a cross-sectional view showing a schematic configuration of a polishing head. Figure 3 is a cross-sectional view showing an example of a retainer assembly. Figure 4 is a plan view showing an example of a membrane film. Figure 5A is an enlarged view of the area enclosed by line 5 in Figure 4, schematically showing how the peripheral edge of the membrane film moves radially inward, and Figure 5B is an enlarged view of the area enclosed by line 5 in Figure 4, schematically showing how the peripheral edge of the membrane film moves radially outward. Figure 6A is a cross-sectional view schematically showing how the wafer is pressed by the membrane film when the storage thickness is large, and Figure 6B is a cross-sectional view schematically showing how the wafer is pressed by the membrane film when the storage thickness is small. Figure 7A is a graph showing an example of experimental results when the wear amount is "0 μm", Figure 7B is a graph showing an example of experimental results when the wear amount is "30 μm", Figure 7C is a graph showing an example of experimental results when the wear amount is "250 μm", and Figure 7D is a graph showing an example of experimental results for an example where the wear amount is "550 μm". Figure 8A is a graph showing an example of experimental results when the wear amount is "850 μm", and Figures 8B and 8C are graphs showing an example of experimental results when the wear amount is "1000 μm". Figure 9 is a graph showing the relationship between the wear amount of the retainer ring and the in-plane uniformity of the wafer after polishing. Figure 10 is a plan view showing an example of a modified membrane film.

[0008] An embodiment of a CMP (Chemical Mechanical Polishing) apparatus will be described with reference to Figures 1 to 10. As shown in Figure 1, the CMP apparatus 10 has a platen 11 and a polishing head 20. The platen 11 has a disc shape. The platen 11 is connected to a rotating shaft 12. The platen 11 rotates in the direction of arrow 13 in Figure 1 as the rotating shaft 12 rotates. A polishing pad 14 is attached to the upper surface of the platen 11. The polishing pad 14 is configured to be replaceable. The polishing pad 14 is, for example, a foamed polyurethane pad in which a nonwoven fabric pad is laminated on a cushion layer. A slurry (not shown) is supplied onto the polishing pad 14. The slurry is a mixture of several slurry formulations containing abrasives and chemicals according to the material of the wafer 15 (see Figure 2) to be polished.

[0009] The polishing head 20 is formed in a disc shape with a smaller diameter than the platen 11. The polishing head 20 is connected to a rotating shaft 21 located above it. The polishing head 20 rotates in the direction of arrow 22 about the rotational axis 20A as the rotating shaft 21 rotates. The polishing head 20 is configured to be able to move up and down in the height direction Z by a lifting device (not shown). The polishing head 20 is configured to be able to hold a wafer 15.

[0010] The CMP apparatus 10 supplies slurry to the polishing pad 14 to form a slurry layer on the surface of the polishing pad 14, and rotates the platen 11 and the polishing head 20. The CMP apparatus 10 then polishes the wafer 15 by pressing the wafer 15, which is held by the polishing head 20, against the polishing pad 14.

[0011] <Polishing Head> As shown in Figure 2, the polishing head 20 comprises a head body 25, a retainer ring 40, and a membrane film 45.

[0012] The head body 25 includes a shaft connecting member 26, a carrier 27, a carrier pressing portion 33, a retainer pressing member 35, a retainer holder 36, a snap ring 38, and a retainer pressing portion 41. The head body 25 may have other configurations.

[0013] The shaft connecting member 26 is connected to the rotating shaft 21. The shaft connecting member 26 is configured to rotate together with the rotating shaft 21. The shaft connecting member 26 is connected to a carrier 27 located below the shaft connecting member 26 via a connecting portion 28. The carrier 27 is configured to rotate together with the shaft connecting member 26.

[0014] A carrier recess 30 is formed in the lower part of the carrier 27, with the rim 29 as its peripheral wall. The carrier 27 has a plurality of first air passages 31 that open into the carrier recess 30. The first air passages 31 open to the peripheral edge of the carrier recess 30. More specifically, one end of the first air passages 31 opens into the carrier recess 30 at equal intervals in the circumferential direction around the rotation axis 21 of the carrier 27. The other end of the first air passages 31 is connected to an air supply source 32.

[0015] The carrier pressing section 33 is provided between the axial connecting member 26 and the carrier 27. The carrier pressing section 33 is an airbag or the like that inflates when air is supplied from the air supply source 43. The carrier pressing section 33 presses the carrier 27 according to the pressure of the supplied air, thereby pressing the wafer 15 housed in the storage pocket 49 against the polishing pad 14.

[0016] The retainer pressing member 35 and the retainer holder 36 are provided to surround the carrier 27. The retainer pressing member 35 is provided to surround the portion of the carrier 27 above the rim 29. The retainer holder 36 is provided to abut the bottom surface of the retainer pressing member 35 and surround the rim 29 of the carrier 27. The carrier 27 is surrounded by the retainer pressing member 35 and the retainer holder 36, forming a second air passage 37 in the polishing head 20. The second air passage 37 connects the space formed by the carrier recess 30 with the external space of the polishing head 20.

[0017] The retainer pressing member 35 and the retainer holder 36 are detachably connected by a snap ring 38. The snap ring 38 connects the retainer pressing member 35 and the retainer holder 36 by fitting into fitting recesses formed on the outer circumference of each of them. After the connection of the retainer pressing member 35 and the retainer holder 36, the snap ring 38 is protected by being covered by a ring cover 39. The head body 25 does not necessarily have to be equipped with a snap ring 38 and a ring cover 39. The retainer pressing member 35 may be connected to the retainer holder 36, or the retainer pressing member 35 and the retainer holder 36 may be integrated.

[0018] A retainer ring 40 is connected to the retainer holder 36 by a plurality of fastening members 55 (see Figure 3). The retainer ring 40 is formed in an annular shape. The retainer ring 40 has an inner surface 61 at approximately the same position as the inner surface of the retainer holder 36. The retainer ring 40 can be made of, for example, polyetheretherketone (PEEK) resin, glass epoxy, or carbon fiber reinforced plastics (CFRP). The retainer holder 36 and the retainer ring 40 sandwich the peripheral edge 45A of the membrane film 45. The inner surface 61 of the retainer ring 40 forms a storage pocket 49 in which a wafer 15 to be polished can be accommodated.

[0019] The retainer pressing portion 41 is located between the shaft connecting member 26 and the carrier 27, and is positioned outside the carrier pressing portion 33. The retainer pressing portion 41 is an airbag or the like that inflates when air is supplied from the air supply source 48. The retainer pressing portion 41 presses the retainer ring 40 against the polishing pad 14 via the retainer pressing member 35 and the retainer holder 36, in accordance with the pressure of the supplied air.

[0020] The membrane film 45 is formed, for example, in a disc shape. The membrane film 45 is provided so that its peripheral edge 45A is sandwiched between the retainer holder 36 and the retainer ring 40. The membrane film 45 is provided so as to cover the carrier recess 30 from below. The membrane film 45 may have adsorption holes that communicate with the air chamber 46 and the storage pocket 49. The membrane film 45 is formed of an elastic material. The membrane film 45 is made of, for example, polyethylene terephthalate (PET) resin, fluororesin, or polyphenylene sulfide (PPS) resin. These are resins that do not easily stretch or contract, such as rubber. However, even if the membrane film 45 is made of a material that easily stretches or contracts, such as rubber, the embodiments and modifications of this invention can still be applied. The space surrounded by the carrier recess 30 and the membrane film 45 is the air chamber 46. In other words, the air chamber 46 is the space between the carrier recess 30 and the membrane film 45 in the height direction Z. The membrane film 45 may also be configured to press the wafer 15 via a backing film (not shown).

[0021] When polishing the wafer 15, the air chamber 46 is controlled to a positive pressure by the supply of pressurized air from the air supply source 32. At this time, excess air in the air chamber 46 is discharged to the outside space through the second air passage 37, and the pressure in the storage pocket 49 is maintained at a pressure lower than the pressure in the air chamber 46, for example, atmospheric pressure. When the pressure in the storage pocket 49 is normal, the membrane film 45 flexes into the storage pocket 49, thereby properly pressing the wafer 15 against the polishing pad 14.

[0022] <Retainer Assembly> The retainer holder 36, retainer ring 40, and membrane film 45 will be described in more detail with reference to Figures 3 to 6.

[0023] As described above, the retainer holder 36 is detachably attached to the retainer pressing member 35. The retainer holder 36 and the retainer ring 40 are connected by a clamping member 55 while holding the membrane film 45 in place. In other words, the retainer holder 36, the retainer ring 40, and the membrane film 45 are configured to be detachably attached to the polishing head 20 as a single integrated part. The integrated retainer holder 36, retainer ring 40, and membrane film 45 is called the retainer assembly.

[0024] As shown in Figure 3, the retainer ring 40 is connected to the retainer holder 36 by a plurality of fastening members 55, with the peripheral edge 45A of the membrane film 45 sandwiched between them. The fastening positions by the fastening members are provided to be at equal intervals in the circumferential direction around the rotational axis 20A. In this embodiment, the retainer ring 40 is connected to the retainer holder 36 by nine fastening members 55. The retainer holder 36 has a shaft hole 56 through which the shaft portion of the fastening member 55 can be inserted and a seating portion 57 on which the head of the fastening member 55 sits at each fastening position. The retainer ring 40 has a female threaded portion 58 at each fastening position into which the shaft portion of the fastening member 55 is screwed. The fastening members 55 connect the retainer holder 36 and the retainer ring 40 with a predetermined fastening torque. The predetermined tightening torque is the torque at which the peripheral edge 45A of the membrane film 45 can move while being held between the retainer holder 36 and the retainer ring 40.

[0025] The retainer ring 40 has a clamping surface 59 and an inclined surface 60. The clamping surface 59 is a flat surface provided perpendicular to the height direction Z. The clamping surface 59 is clamped to the retainer holder 36 by a clamping member 55 via the peripheral edge 45A of the membrane film 45. The inclined surface 60 is a flat surface that is inclined at a predetermined angle (acute angle) from the inner edge of the clamping surface 59 toward the radially inward direction of the rotational center axis 20A. The inclined surface 60 extends to the upper edge of the inner circumferential surface 61 that forms the storage pocket 49, while maintaining the predetermined angle of inclination. The angle of inclination is, for example, 30°. As a result, the corner between the inclined surface 60 and the inner circumferential surface 61 is formed in an obtuse angle in cross-section. The angle of inclination is preferably 25° or more and 45° or less. The retainer holder 36 has a parallel surface 62 parallel to the inclined surface 60 such that a gap slightly larger than the thickness of the membrane film 45 is formed between it and the inclined surface 60.

[0026] The retainer ring 40 has an overall thickness t1 and a storage thickness t2. The storage thickness t2 is the thickness of the storage pocket 49. The retainer ring 40 is manufactured such that the storage thickness t2 is 30% or more of the overall thickness t1, i.e., t2 ≥ 0.3 × t1. The storage thickness t2 gradually decreases due to wear of the retainer ring 40 accompanying the polishing of the wafer 15.

[0027] As the wafer thickness t2 decreases, the polishing head 20's ability to hold the wafer 15 decreases. Therefore, the retainer ring 40 needs to be replaced periodically. When replacing the retainer ring 40, first, the ring cover 39 is removed to expose the snap ring 38. Next, the snap ring 38 is removed to release the connection between the retainer pressing member 35 and the retainer holder 36. Then, by removing the retainer holder 36 from the retainer pressing member 35, the retainer assembly is removed from the polishing head 20.

[0028] Next, the retainer ring 40 is removed from the retainer holder 36, and then the new retainer ring 40 is tightened to the retainer holder 36 with a predetermined tightening torque so as to sandwich the membrane film 45. This completes the assembly of the retainer. Finally, the retainer holder 36 is connected to the retainer pressing member 35, and the retainer assembly is attached to the polishing head 20, thereby completing the replacement of the retainer ring 40.

[0029] By increasing the storage thickness t2, the retainer ring 40 can be used without affecting the polishing state of the wafer even if its shape changes, thereby extending the lifespan of the retainer ring 40. However, when the storage thickness t2 is increased, even when polishing wafers 15 of the same size, the polishing conditions of the wafer 15 will differ significantly depending on whether a retainer ring 40 that is not worn or one that is worn to the point of needing replacement is used. In other words, when the storage thickness t2 is increased, the conditions under which the membrane film 45 presses against the wafer 15 change significantly due to the wear of the retainer ring 40. In particular, when the membrane film is fixed as in the conventional method, when polishing using a retainer ring 40 that is not worn, there is a possibility that the membrane film 45 may not be able to make sufficient contact with the outer periphery of the wafer 15, making it difficult for the outer periphery of the wafer 15 to be pressed by the membrane film 45.

[0030] As shown in Figure 4, an insertion hole 65 is formed in the peripheral edge 45A of the membrane film 45 at a position corresponding to the tightening position, through which the shaft of the tightening member 55 can be inserted. The insertion hole 65 is formed in the shape of an elongated hole that is long in the radial direction of the rotational axis 20A. That is, the insertion hole 65 is formed such that the amount of movement of the peripheral edge 45A near the tightening position is greater in the radial direction than in the circumferential direction of the rotational axis 20A. Note that in Figure 4, the area outside the boundary line 66 is the peripheral edge 45A.

[0031] In other words, as shown in Figure 5A, the membrane film 45 flexes into the housing pocket 49 when pressurized air is supplied to the air chamber 46. At that time, the membrane film 45 is configured to be elastically deformable so that its peripheral edge 45A moves radially inward by an amount corresponding to the housing thickness t2 of the retainer ring 40 and the thickness of the wafer 15 at that time. Furthermore, as shown in Figure 5B, the membrane film 45 is configured so that its peripheral edge 45A gradually moves radially outward as the retainer ring 40 wears down due to the reaction force received when the wafer 15 is pressed. By configuring the peripheral edge 45A of the membrane film 45 to move radially in this way, it is possible to increase the housing thickness t2 while also allowing the outer periphery of the wafer 15 to be pressed, that is, to increase the allowable wear amount of the retainer ring 40.

[0032] For example, as shown in Figure 6A, immediately after the retainer ring 40 is replaced, that is, when the storage thickness t2 is at its maximum thickness, the peripheral edge 45A of the membrane film 45 moves radially inward by a large amount. On the other hand, as shown in Figure 6B, when the storage thickness t2 is less than the maximum thickness, the peripheral edge 45A of the membrane film 45 moves radially inward by a small amount. By configuring the peripheral edge 45A of the membrane film 45 to be movable radially in this way, the wafer 15 can be properly pressed even when the storage thickness t2 is increased.

[0033] <Verification Experiment> The inventors conducted a verification experiment on the wafer polishing rate when using a retainer ring 40 in which an elongated hole 65 is formed in the membrane film 45 and the storage thickness t2 is increased.

[0034] In this experiment, a conventional retainer ring made of PEEK resin was used as the comparative example, and a PEEK resin retainer ring in which elongated insertion holes 65 were formed in the membrane film 45 and the storage thickness t2 was increased by 1000 μm compared to the comparative example was used as the example. In addition, a SiC wafer was polished under the same processing conditions while slurry was supplied to the polishing pad 14.

[0035] The experimental results are shown in Figures 7A to 7D, 8A to 8C, and 9. The graphs in Figures 7A to 7D and 8A to 8C show the polishing amount distribution. In each graph, the horizontal axis represents the radial position (in mm) with the center of the wafer as the origin, and the vertical axis represents the rate ratio. The rate ratio is the value obtained by dividing the polishing rate Rx at position x (where x is the radial position) by the average polishing rate Rave. For example, when x is an integer from 1 to n, the average polishing rate Rave is calculated as (R1 + R2 + ... + Rn) / n, and the rate ratio at position k (k ∈ x) is calculated as Rk / Rave. That is, positions where the rate ratio is greater than 1 are positions where the polishing rate is greater than the average polishing rate, and positions where the rate ratio is less than 1 are positions where the polishing rate is less than the average polishing rate.

[0036] Figures 7A to 7D and 8A to 8C show the experimental results of the comparative examples with solid lines. Figure 7A is a graph showing an example of experimental results for an example where the retainer ring 40 has a wear amount of "0 μm", i.e., a new retainer ring. Figure 7B is a graph showing an example of experimental results for an example where the retainer ring 40 has a wear amount of "30 μm". Figure 7C is a graph showing an example of experimental results for an example where the retainer ring 40 has a wear amount of "250 μm". Figure 7D is a graph showing an example of experimental results for an example where the retainer ring 40 has a wear amount of "550 μm". Figure 8A is a graph showing an example of experimental results for an example where the retainer ring 40 has a wear amount of "850 μm". Figures 8B and 8C are graphs showing an example of experimental results for an example where the retainer ring 40 has worn down to a wear amount of "1000 μm", i.e., until the housing thickness t2 is the same as the comparative example.

[0037] As shown in Figure 7A, when the wear amount of the retainer ring 40 was "0 μm", the rate ratio at the wafer edge was lower than that of the comparative example, but the rate ratio in other areas was equivalent to that of the comparative example. As shown in Figure 7B, when the wear amount of the retainer ring 40 was "30 μm", the rate ratio at the wafer edge was slightly lower than that of the comparative example, but the rate ratio in other areas was equivalent to that of the comparative example. In the results shown in Figures 7A and 7B, the rate ratio is sufficiently improved compared to that obtained with the same wear amount using a conventional retainer ring made of PEEK resin with a storage thickness t2 increased by 1000 μm. As shown in Figures 7C, 7D, and 8A to 8C, when the wear amount of the retainer ring 40 was "250 μm", "550 μm", "850 μm", and "1000 μm", the rate ratio was equivalent to that of the comparative example across the entire area. Thus, it was confirmed that although there are differences in the rate ratio at the wafer edge, the rate ratio equivalent to that of the comparative example can be obtained.

[0038] Figure 9 is a graph showing the relationship between the amount of retainer ring wear and the in-plane uniformity of the wafer after polishing, based on the experimental results shown in Figures 7A to 7D and Figures 8A to 8C. In Figure 9, the horizontal axis represents the amount of retainer ring wear (in μm), and the vertical axis represents the in-plane uniformity (in %) obtained by the (Max-Min) method. In-plane uniformity indicates the variation in processing uniformity between wafers, and a smaller value indicates smaller variation between wafers. In Figure 9, the relationship between the amount of retainer ring wear and the in-plane uniformity of the wafer after polishing in the comparative example is shown by a dashed line, and the relationship between the amount of retainer ring wear and the in-plane uniformity of the wafer after polishing in the example is shown by a solid line.

[0039] As shown in Figure 9, when the retainer ring wear amount was "0 μm", the in-plane uniformity was greater than that of the comparative example. However, when the retainer ring wear amount was "30 μm" or more, it was confirmed that better in-plane uniformity than that of the comparative example could be obtained. Furthermore, when the retainer ring wear amount was "0 μm", it was confirmed that better in-plane uniformity could be obtained by performing a dummy run that slightly wore down the retainer ring.

[0040] The operation and effect of the present embodiment will be described. (1) A CMP apparatus 10 includes a polishing head 20 configured to be capable of holding a wafer 15 and polishing the wafer 15 by rotating while pressing the wafer 15 against a polishing pad 14. The polishing head 20 includes: a head main body 25 having an air chamber 46 to which pressurized air is supplied; a retainer ring 40 having an accommodation pocket 49 for accommodating the wafer 15; and a membrane film 45 having a peripheral edge portion 45A sandwiched between the head main body 25 and the retainer ring 40, the membrane film 45 partitioning the air chamber 46 and the accommodation pocket 49. The peripheral edge portion 45A of the membrane film 45 is held between the head main body 25 and the retainer ring 40 so as to be movable in the radial direction.

[0041] According to this configuration, even when the accommodation thickness t2, that is, the wear allowance of the retainer ring 40 is increased in order to extend the service life of the retainer ring 40, the wafer 15 can be appropriately pressed by the membrane film 45. Further, increasing the accommodation thickness t2 also improves the degree of freedom regarding the thickness of the wafer 15 that can be polished.

[0042] (2) The peripheral edge portion 45A of the membrane film 45 is held between the retainer holder 36 of the head main body 25 and the retainer ring 40 such that the movable amount in the radial direction is larger than that in the circumferential direction intersecting the radial direction.

[0043] According to this configuration, the degree of freedom regarding the radial movement amount of the peripheral edge portion 45A of the membrane film 45 is improved. As a result, the wear allowance of the retainer ring 40 can be increased.

[0044] (3) The retainer holder 36 and the retainer ring 40 are coupled by a fastening member 55 so as to sandwich the peripheral edge portion 45A of the membrane film 45 therebetween. The membrane film 45 has an insertion hole 65 through which the fastening member 55 is inserted, the insertion hole 65 being formed in a size that allows the membrane film 45 to move relative to the fastening member 55.

[0045] According to such a configuration, the amount of movement of the peripheral edge portion 45A of the membrane film 45 in the radial direction can be adjusted by the position of the fastening member 55 and the shape of the insertion hole 65. In addition, excessive movement of the peripheral edge portion 45A can be restricted by the peripheral edge of the insertion hole 65.

[0046] (4) The insertion hole 65 has a long hole shape elongated in the radial direction of the membrane film 45. According to such a configuration, while suppressing excessive movement of the membrane film 45 in the radial direction, the state where the peripheral edge portion 45A of the membrane film 45 is clamped can be reliably maintained. In addition, positioning of the membrane film 45 can be easily performed when replacing the retainer ring 40.

[0047] (5) The retainer ring 40 has an inclined surface 60 that inclines radially inward from the inner edge of a fastening surface 59 fastened by the fastening member 55 and extends to the upper edge of an inner circumferential surface 61 that forms the accommodation pocket 49.

[0048] According to such a configuration, since the movement of the peripheral edge portion 45A in the radial direction is smoothly performed, the entire wafer 15 can be pressed by the membrane film 45 even when the accommodation thickness t2 is large. As a result, variation in polishing rate can be suppressed.

[0049] Further, the membrane film 45 bends into the accommodation pocket 49 starting from a corner formed by the inclined surface 60 and the inner circumferential surface 61. According to the above configuration, since the angle formed by the inclined surface 60 and the inner circumferential surface 61 is an obtuse angle, the stress generated in the membrane film 45 at the starting point of bending can be reduced compared to, for example, a case where the inclined surface 60 and the inner circumferential surface 61 are connected via a connecting surface parallel to the fastening surface 59.

[0050] (6) As described above, the inclination angle of the inclined surface 60 with respect to the fastening surface 59 is preferably 25° or more and 45° or less. When the inclination angle is 25° or more, the stress generated in the membrane film 45 at the starting point of bending can be sufficiently reduced. When the inclination angle is 45° or less, the overall thickness t1 can be suppressed even if the inclined surface 60 and the inner circumferential surface 61 are directly connected.

[0051] (7) The retainer ring 40 is formed such that when the total thickness is t1 and the thickness of the receiving pocket is t2, t2 ≥ 0.3 × t1. With this configuration, the wear tolerance can be increased while maintaining the overall balance of the polishing head 20 so that a sufficient polishing rate can be obtained.

[0052] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they are not technically contradictory. The through hole 65 is not limited to a through hole formed in the peripheral edge 45A of the membrane film 45. For example, as shown in Figure 10, the through hole may be a notched through hole 70 formed up to the outer edge of the membrane film 45. For example, even if the accommodating thickness is sufficiently large compared to the wafer thickness, the through hole 70 does not have to be an elongated hole shape, and may be circular, square, rectangular, or any other shape, as long as it is movable enough for the membrane film 45 to make sufficient contact with the wafer and maintain a pressurized state. Even with such a configuration, the degree of freedom regarding the amount of radial movement of the peripheral edge 45A of the membrane film 45 is improved.

[0053] - The receiving thickness t2 may be less than 30% of the total thickness t1. - The inclined surface 60 of the retainer ring 40 may be inclined from the inner edge of the clamping surface 59 and may not extend to the upper edge of the inner circumferential surface 61. That is, in addition to the clamping surface 59 and the inclined surface 60, the retainer ring 40 may also have a horizontal surface that extends from the inner edge of the inclined surface 60 to the upper edge of the inner circumferential surface 61.

[0054] The peripheral portion 45A of the membrane film 45 may be configured to be more elastically deformable than the portion other than the peripheral portion 45A. This configuration can be achieved, for example, by forming the membrane film 45 from a composite material such that the elastic modulus differs between the peripheral portion 45A and the portion other than the peripheral portion 45A. Even with this configuration, radial movement of the peripheral portion 45A can be achieved.

[0055] - The clamping member 55 and the insertion hole 65 are not required if the peripheral edge 45A of the membrane film 45 is sandwiched between the head body 25 and the retainer ring 40 so that the membrane film 45 can move at least radially. In this case, a stopper may be provided to restrict the amount of radial movement of the membrane film 45 so that the membrane film 45 does not come off.

[0056] Furthermore, this disclosure is not limited to the embodiments and modifications described above, and can be implemented with various modifications without departing from the spirit of this disclosure. All of these modifications are included in the technical concept of this disclosure. Also, unless otherwise specified in the specification, each component of this disclosure is not limited to one, but may be multiple.

[0057] 10...CMP device, 11...platen, 12...rotating shaft, 13...arrow, 14...polishing pad, 15...wafer, 20...polishing head, 20A...rotating center axis, 21...rotating shaft, 22...arrow, 25...head body, 26...shaft connecting member, 27...carrier, 28...connecting part, 29...rim, 30...carrier recess, 31...first air passage, 32...air supply source, 33...carrier pressing part, 35...retainer pressing member, 36...retainer holder, 37... Second air passage, 38... snap ring, 39... ring cover, 40... retainer ring, 41... retainer pressing part, 43... air supply source, 45... membrane film, 45A... peripheral part, 46... air chamber, 48... air supply source, 49... housing pocket, 55... fastening member, 56... shaft hole, 57... seating part, 58... female thread part, 59... fastening surface, 60... inclined surface, 61... inner circumferential surface, 62... parallel surface, 65... insertion hole, 66... ​​boundary line, 70... insertion hole.

Claims

1. A CMP apparatus comprising a polishing head configured to hold a wafer and polishing the wafer by rotating it while pressing it against a polishing pad, wherein the polishing head comprises: a head body having an air chamber to which pressurized air is supplied; a retainer ring having a storage pocket for accommodating the wafer; and a membrane film having a peripheral edge sandwiched between the head body and the retainer ring, and partitioning the air chamber and the storage pocket, wherein the peripheral edge of the membrane film is held radially movably between the head body and the retainer ring.

2. The CMP apparatus according to claim 1, wherein the peripheral edge of the membrane film is sandwiched between the head body and the retainer ring such that the amount of movement in the radial direction is greater than the amount of movement in the circumferential direction intersecting the radial direction.

3. The CMP apparatus according to claim 2, comprising the head body, the retainer ring, and a fastening member for fastening the membrane film, wherein the membrane film has a hole formed to which the fastening member is inserted and which is sized to allow the membrane film to move relative to the fastening member.

4. The CMP apparatus according to claim 3, wherein the holes are elongated holes that are longer in the radial direction of the membrane film.

5. The CMP apparatus according to claim 3, wherein the hole is a notch formed to the outer edge of the membrane film.

6. The CMP apparatus according to any one of claims 3 to 5, wherein the retainer ring has an inclined surface that slopes radially inward from the inner edge of the clamping surface that is clamped to the clamping member, and extends to the inner circumferential surface that forms the receiving pocket.

7. The CMP apparatus according to claim 6, wherein when the total thickness of the retainer ring is t1 and the thickness of the receiving pocket is t2, t2 ≥ 0.3 × t1.

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