Polishing head, polishing apparatus, and polishing method

Abstract

The present invention pertains to a polishing head, a polishing apparatus, and a polishing method. The polishing apparatus is provided with a polishing head and a head rotating mechanism. The polishing head includes a pad member that supports a polishing tape. The head rotating mechanism is configured to rotate the pad member and the polishing tape together.

Description

Polishing head, polishing device, and polishing method

[0001] The present invention relates to a polishing head, a polishing apparatus, and a polishing method.

[0002] In the manufacture of semiconductor devices, various types of films are formed on wafers, which are an example of substrates. Wafers are polished to remove unwanted portions of the films and surface irregularities. Chemical mechanical polishing (CMP) is a typical wafer polishing technique.

[0003] JP 2016-58724 A

[0004] The precision required for each process in the manufacturing of semiconductor devices today has already reached the order of several nanometers, and CMP is no exception. Furthermore, with the increasing integration density of semiconductor integrated circuits, miniaturization and multi-layering are accelerating.

[0005] Therefore, to achieve these miniaturization and multi-layering, it is necessary to limit the variation in film thickness after CMP to the order of a few nanometers across the entire surface of the wafer. To meet this requirement, it is necessary to precisely control the film thickness profile of the wafer for each small region on the wafer.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a polishing head, a polishing apparatus, and a polishing method that are capable of controlling the film thickness profile of a substrate with high precision.

[0007] In one aspect, a polishing apparatus is provided, comprising: a substrate holder configured to hold a substrate and rotate the substrate at a predetermined rotation angle; a polishing head configured to press a polishing tape against the substrate held by the substrate holder; and a head rotation mechanism configured to rotate the polishing head. The polishing head includes a pad member that supports the polishing tape, and the head rotation mechanism is configured to rotate the pad member together with the polishing tape.

[0008] In one aspect, the polishing head includes a pad pressing mechanism that applies a pressing force to the pad member to press the polishing tape against the substrate when the head rotation mechanism rotates the polishing tape and the pad member. In one aspect, the polishing apparatus includes a rotary joint that connects the polishing head and the head rotation mechanism, and the polishing head is connected to a rotating part of the rotary joint. In one aspect, the pad member has a diameter smaller than that of the substrate.

[0009] In one aspect, a polishing head configured to press a polishing tool against a substrate is provided, the polishing head including a pressure pad structure configured to support the polishing tool and switch a pressing area against the substrate, and a pad pressing mechanism that applies a pressing force to the pressure pad structure to press the polishing tool against the substrate.

[0010] In one aspect, the pressure pad structure includes a pad member and an annular pad surrounding the pad member. In one aspect, the pressure pad structure is configured to switch the pressure area between a first pressure area formed by pressing the pad member against the substrate and a second pressure area formed by pressing the pad member and the annular pad against the substrate. In one aspect, the pad pressing mechanism includes a first pressing device connected to the pad member and a second pressing device connected to the annular pad. The first pressing device presses the pad member against the substrate to form the first pressure area, and the first and second pressing devices press the pad member and the annular pad against the substrate to form the second pressure area. In one aspect, the polishing tool corresponds to a polishing tape or a grindstone supported by the pressure pad structure.

[0011] In one aspect, a polishing apparatus is provided, the polishing apparatus including a substrate holder configured to hold a substrate and rotate the substrate at a predetermined rotation angle, and a polishing head configured to press a polishing tool against the substrate held by the substrate holder.

[0012] In one embodiment, the polishing apparatus includes a head rotation mechanism that rotates the polishing head, and the head rotation mechanism is configured to rotate the pressure pad structure together with the polishing tool.

[0013] In one aspect, a polishing method is provided, comprising: holding a substrate and rotating the substrate at a predetermined rotation angle; and pressing a polishing tape supported by a pad member of a polishing head against the substrate. The pressing of the polishing tape against the substrate includes pressing the polishing tape against the substrate while rotating the pad member together with the polishing tape.

[0014] In one aspect, a polishing method is provided, the polishing method including the steps of holding a substrate and rotating the substrate at a predetermined rotation angle, and pressing a polishing tool supported by a pressure pad structure of a polishing head against the substrate, wherein the step of pressing the polishing tool against the substrate includes switching a pressing area against the substrate by the pressure pad structure.

[0015] In one aspect, the pressure pad structure comprises a pad member and an annular pad surrounding the pad member, and the step of pressing the polishing tool against the substrate includes a step of switching the pressure area between a first pressure area formed by pressing the pad member against the substrate and a second pressure area formed by pressing the pad member and the annular pad against the substrate.

[0016] The polishing head is configured to polish a localized area of ​​the substrate with pinpoint accuracy, thereby enabling precise control of the film thickness profile of the substrate.

[0017] 6A is a diagram showing an embodiment of a polishing apparatus; FIG. 6B is a diagram showing the polishing head coupled to a shaft; FIG. 6C is an enlarged view of the polishing head; FIG. 6A is a diagram showing the head swinging mechanism that swings the polishing head; FIG. 6B is a diagram showing the swing trajectory of the polishing head and the rotation trajectory of the stage; FIG. 6C is a flowchart showing the wafer polishing process; FIG. 6D is a diagram showing the polishing head that polishes the area to be polished; FIG. 6E is a diagram showing the area to be polished polished by the polishing head; FIG. 6F is a diagram showing the pad pressing mechanism coupled to the pressure pad structure; FIG. 6G is a diagram showing multiple pressing areas of the pressure pad structure; FIG. 6H is a diagram showing multiple pressing areas of the pressure pad structure; FIG. 6I is a diagram showing a first area to be polished and a second area to be polished; FIG. 6I is a diagram showing the pressure pad structure that supports a grinding wheel, which is an example of a polishing tool;

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, identical or corresponding components are designated by the same reference numerals, and duplicated descriptions will be omitted. In the multiple embodiments described below, the configuration of an embodiment that is not particularly described is the same as that of other embodiments, and therefore duplicated descriptions will be omitted.

[0019] 1 is a diagram showing an embodiment of a polishing apparatus, and is provided with a substrate holding unit WH that holds a wafer W (an example of a substrate) and rotates the wafer W at a predetermined rotation angle (in other words, moves it back and forth), a polishing head PH that presses a polishing tape PT (an example of a polishing tool) against the wafer W held by the substrate holding unit WH, and a head rotation mechanism 12 that rotates the polishing head PH.

[0020] 1 and 2, the substrate holding unit WH includes a stage 1 that holds the wafer W with the surface to be polished facing upward, a stage shaft 2 connected to the stage 1, and a stage actuator 3 that is connected to the stage shaft 2 and operates the stage 1 via the stage shaft 2.

[0021] The stage 1 extends horizontally and serves as a mounting table for a wafer W. The stage axis 2 extends along a central axis CL that passes through the center of the stage 1. The stage actuator 3 is configured to rotate the stage 1 by a predetermined rotation angle. An example of the stage actuator 3 is a precision motor such as a servo motor.

[0022] The stage actuator 3 rotates the stage 1 about a central axis CL through its operation (see the hollow arrow in FIG. 2 ). More specifically, with the wafer W placed on the stage 1, the stage actuator 3 is configured to rotate the stage 1 in one direction (e.g., clockwise) by a predetermined rotation angle, and then rotate the stage 1 in the other direction (e.g., counterclockwise) by a predetermined rotation angle. The predetermined rotation angle is a rotation angle less than 360 degrees and is determined based on the polishing conditions for the wafer W.

[0023] 1, the polishing apparatus PA includes a liquid supply nozzle 20 disposed above a wafer W held on a stage 1. The liquid supply nozzle 20 is configured to supply a liquid (e.g., pure water) onto the surface of the wafer W to be polished while the wafer W is being polished.

[0024] 3 is a perspective view showing the polishing head PH. The polishing head PH includes a pad member 11 that supports the polishing tape PT, a pad pressing mechanism 25 that applies a pressing force to the pad member 11 to press the polishing tape PT against the wafer W when the head rotation mechanism 12 rotates the polishing tape PT and the pad member 11, and a holding base 17 that holds the pad pressing mechanism 25.

[0025] The holding base 17 holds the pad pressing mechanism 25 so that the pad pressing mechanism 25 faces downward. The pad pressing mechanism 25 is configured by, for example, an air cylinder. In this case, the pad pressing mechanism 25 as an air cylinder includes a rod that can move up and down in the vertical direction and a cylinder that accommodates the rod.

[0026] The pad member 11 is fixed to a pad pressing mechanism 25 (e.g., a rod of an air cylinder). Therefore, the pad pressing mechanism 25 is configured to press down the pad member 11 arranged on the back side of the polishing tape PT (i.e., the back side of the polishing surface of the polishing tape PT) by its operation, and press the polishing tape PT against the surface to be polished of the wafer W.

[0027] The head rotation mechanism 12 is configured to rotate the pad member 11 together with the polishing tape PT (see the white arrow in FIG. 3 ). The head rotation mechanism 12 includes a shaft 14 connected to the polishing head PH, a head actuator (e.g., a motor) 26 that rotates the polishing head PH via the shaft 14, and a belt 15 stretched around the shaft 14 and the head actuator 26.

[0028] Fig. 4 shows the polishing head connected to the shaft. Fig. 5 is an enlarged view of the polishing head. The head actuator 26 is fixed on a mounting plate 13 that extends horizontally (i.e., parallel to the stage 1). The shaft 14 passes through a through-hole 13a formed in the mounting plate 13 and is connected to the polishing head PH located below the mounting plate 13.

[0029] The head actuator 26 rotates the belt 15 by its operation, and transmits the rotational force of the belt 15 to the shaft 14. When the shaft 14 rotates, the polishing head PH connected to the shaft 14 rotates together with the shaft 14.

[0030] As shown in FIGS. 4 and 5, the polishing head PH includes a tape supply mechanism 19 configured to supply the polishing tape PT to the pad member 11 and collect the polishing tape PT from the pad member 11 .

[0031] The tape supply mechanism 19 includes a tape unwinding reel 18A that supplies the polishing tape PT to the pad member 11, a tape winding reel 18B that recovers the polishing tape PT supplied to the pad member 11, and a plurality of guide rollers 18C, 18D for supporting the polishing tape PT.

[0032] The tape supply reel 18A and the tape take-up reel 18B are each connected to a tension motor (not shown). The tension motor applies a predetermined torque to each of the tape supply reel 18A and the tape take-up reel 18B, thereby applying a predetermined tension to the polishing tape PT.

[0033] The guide rollers 18C, 18D are arranged on both sides of the pad member 11 in the traveling direction of the polishing tape PT, and are arranged in the traveling path of the polishing tape PT between the tape supply reel 18A and the tape take-up reel 18B.

[0034] The polishing apparatus PA includes a rotary joint 16 that connects the polishing head PH and the head rotation mechanism 12. The rotary joint 16 has a cylindrical fixed portion 16a fixed to the mounting plate 13, and a rotating portion 16b connected to the fixed portion 16a and fixed to the holding base 17.

[0035] The shaft 14 is inserted into the fixed portion 16a of the rotary joint 16 and is connected to the rotating portion 16b located below the fixed portion 16a. Therefore, the rotational force of the shaft 14 generated by driving the head actuator 26 is transmitted to the rotating portion 16b and the holding base 17.

[0036] The tape supply mechanism 19 and the pad pressing mechanism 25 (and the pad member 11) are attached to the holding base 17. Therefore, when the shaft 14 rotates, the tape supply mechanism 19 and the pad pressing mechanism 25 (and the pad member 11) attached to the holding base 17 rotate together with the shaft 14. In this way, the head rotation mechanism 12 rotates the polishing head PH together with the polishing tape PT.

[0037] Although not shown, a power line for supplying power (e.g., compressed gas) to the pad pressing mechanism 25 is connected to the pad pressing mechanism 25 via the rotary joint 16. Similarly, a power line for supplying power to the tape supply mechanism 19 is connected to the tape supply mechanism 19 via the rotary joint 16.

[0038] 6A is a perspective view showing a head swing mechanism that swings the polishing head, and FIG. 6B is a diagram showing the swing locus of the polishing head and the rotation locus of the stage. As shown in FIG. 6A, the polishing apparatus PA is provided with a head swing mechanism 30 that swings the polishing head PH.

[0039] The head swing mechanism 30 comprises a swing arm 31 extending parallel to the mounting plate 13, a connecting shaft 32 connecting the swing arm 31 and the mounting plate 13, a drive unit (e.g., a servo motor) 35, and a transmission shaft 33 connecting the swing arm 31 and the drive unit 35 and transmitting the driving force of the drive unit 35 to the swing arm 31.

[0040] The driving device 35 swings the swing arm 31 via the transmission shaft 33. The swing force of the swing arm 31 is transmitted to the polishing head PH connected to the shaft 14 via the connecting shaft 32 and the mounting plate 13.

[0041] 6B , when the stage actuator 3 is driven, the stage 1 reciprocates at a predetermined rotation angle along a rotation locus A1. When the drive device 35 is driven, the pad member 11 of the polishing head PH moves along a swing locus A2 on the wafer W. Therefore, the head swing mechanism 30 can move the polishing head PH to a desired polishing position in the radial direction of the wafer W by its operation.

[0042] The polishing apparatus PA includes a control device 50 that controls the operations of its components (e.g., the stage actuator 3, the head actuator 26, the pad pressing mechanism 25, the drive device 35, etc.). The control device 50 includes a storage device 50a that stores a program, and an arithmetic device 50b that executes calculations in accordance with instructions included in the program.

[0043] The storage device 50a includes a main storage device such as a RAM, and an auxiliary storage device such as a hard disk drive (HDD), a solid state drive (SSD), etc. Examples of the computing device 50b include a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit).

[0044] 7 is a flowchart showing the wafer polishing process. As shown in steps S101 and S102 in Fig. 7, before starting polishing of the wafer W, the control device 50 measures the initial film thickness of the entire surface to be polished of the wafer W and creates an initial film thickness profile of the wafer W.

[0045] A stand-alone film thickness measuring device (not shown) or a film thickness sensor (not shown) provided in the polishing apparatus PA may be used as a method for measuring the initial film thickness of the wafer W. The control device 50 measures the initial film thickness of the wafer W based on a film thickness signal acquired by the film thickness measuring device or the film thickness sensor.

[0046] In order to reduce the variation in the film thickness of the wafer W and accurately control the film thickness profile of the wafer W, it is necessary to pinpoint polish a localized region of the wafer W. Therefore, the control device 50 determines the region to be polished on the polishing surface of the wafer W based on the initial film thickness profile of the wafer W.

[0047] The polishing target region is, for example, a local region where the film thickness on the polishing surface of the wafer W is thicker than a predetermined reference film thickness. The control device 50 may compare the reference film thickness with the initial film thickness of the wafer W and determine the region that exceeds a predetermined tolerance range as the polishing target region of the wafer W. Film thickness data corresponding to the reference film thickness and the polishing target region may be stored in the storage device 50a.

[0048] After step S102, the control device 50 operates the drive device 35 to move the polishing head PH to a predetermined polishing position (more specifically, the area to be polished on the wafer W) and starts polishing the area to be polished on the wafer W (see step S103).

[0049] At the start of polishing the wafer W, the control device 50 operates the head actuator 26 to rotate the polishing head PH and operates the tape supply mechanism 19 to advance the polishing tape PT. In this state, the control device 50 operates the pad pressing mechanism 25 to press down the pad member 11 and press the polishing tape PT supported by the pad member 11 against the area of ​​the wafer W to be polished.

[0050] Fig. 8 is a diagram showing a polishing head polishing a target area to be polished. Fig. 9 is a diagram showing the target area to be polished polished by the polishing head. As shown in Fig. 8, when the target area to be polished TA is larger than the pressing area of ​​the pad member 11 against the wafer W, the control device 50 operates the stage actuator 3 to reciprocate the stage 1 at a predetermined rotation angle along the rotation trajectory A1. In this embodiment, the pressing area corresponds to the diameter of the pad member 11. The diameter of the pad member 11 is smaller than the diameter of the wafer W.

[0051] During polishing of the wafer W, the control device 50 operates the stage actuator 3 but does not operate the drive device 35. Therefore, the polishing head PH moves back and forth relatively over the polishing target area of ​​the wafer W along the rotational locus A3 due to the reciprocating movement of the stage 1.

[0052] In this way, the control device 50 moves the stage 1 back and forth while pressing the polishing tape PT supported by the pad member 11 against the polishing target area TA of the wafer W, so that the polishing head PH polishes the wafer W in an arc shape (see Figure 9).

[0053] Indicators such as the polishing accuracy of the wafer W and the amount of polishing per unit time (polishing rate) depend on polishing conditions such as the rotation speed of the stage 1, the rotation speed of the polishing head PH, the advancement speed of the polishing tape PT, etc. Therefore, the control device 50 may change the polishing conditions while the wafer W is being polished.

[0054] In one embodiment, when the polishing target area TA is smaller than the pressing area of ​​the pad member 11, it is not necessary to rotate the stage 1 by a predetermined rotation angle. In this case, the control device 50 operates the head rotation mechanism 12, the pad pressing mechanism 25, and the tape supply mechanism 19 without rotating the stage 1, and polishes the polishing target area TA of the wafer W with the polishing head PH.

[0055] According to this embodiment, the polishing head PH is configured to press the polishing tape PT against the polishing target area TA of the wafer W via a pad member 11 that is smaller than the diameter of the wafer W. Therefore, the polishing head PH can pinpoint polish a localized area (i.e., the polishing target area TA) of the wafer W. As a result, the polishing apparatus PA can accurately control the film thickness profile of the wafer W.

[0056] 7, the control device 50 determines whether the film thickness of the wafer W has reached a predetermined target film thickness (i.e., whether the polishing end point has been reached) (see step S104). For example, the control device 50 may determine the polishing end point based on a predetermined polishing time, or may determine the polishing end point based on a comparison result between the current film thickness and the target film thickness. Film thickness data corresponding to the target film thickness is stored in the storage device 50a.

[0057] If the film thickness of the wafer W has not reached the target film thickness (see "No" in step S104), the control device 50 continues polishing the wafer W. On the other hand, if the film thickness of the wafer W has reached the target film thickness (see "Yes" in step S104), the control device 50 ends polishing the wafer W (see step S105).

[0058] Fig. 10 is a perspective view showing another embodiment of the polishing head. Fig. 10 shows only the main components of the polishing head PH. Although not shown, the polishing apparatus PA includes components such as a head rotation mechanism 12 that rotates the polishing head PH according to the embodiment shown in Fig. 10 and a tape supply mechanism 19.

[0059] In the embodiment shown in Figure 10, the polishing head PH is equipped with a pressing pad structure PS that supports a polishing tape PT, which is an example of a polishing tool, and is configured to switch the pressing area against the wafer W, and a pad pressing mechanism PM that applies a pressing force to the pressing pad structure PS to press the polishing tape PT against the wafer W.

[0060] The pressure pad structure PS includes a pad member 11A corresponding to the pad member 11 according to the embodiment described with reference to FIGS. 1 to 9, and annular pads 11B and 11C surrounding the pad member 11A.

[0061] The annular pads 11B and 11C are arranged concentrically with the pad member 11A. The annular pad 11B is arranged to surround the pad member 11A, and the annular pad 11C is arranged to surround the annular pad 11B (and the pad member 11A). In other words, the annular pad 11C has a larger outer diameter than the annular pad 11B.

[0062] In this embodiment, the pressure pad structure PS includes two annular pads 11B and 11C. However, in one embodiment, the pressure pad structure PS may include a single annular pad or three or more annular pads. The pressing area of ​​the pressure pad structure PS depends on the number of annular pads. Therefore, the number of annular pads may be determined based on conditions such as the type of wafer W to be polished and the size of the area to be polished.

[0063] 11 is a diagram showing a pad pressing mechanism connected to the pressure pad structure. As shown in Fig. 11, the pad pressing mechanism PM includes a first pressing device 25A connected to the pad member 11A, a second pressing device 25B connected to the annular pad 11B, and a third pressing device 25C connected to the annular pad 11C.

[0064] The number of pressing devices corresponds to the number of components of the pressure pad structure PS. For example, if the pressure pad structure PS includes the pad member 11A and the annular pad 11B, the pad pressing mechanism PM includes the first pressing device 25A and the second pressing device 25B.

[0065] In this embodiment, each of the first pressing device 25A to the third pressing device 25C has the same configuration as the pressing mechanism 25 according to the embodiment described with reference to Figures 1 to 9. Therefore, each of the first pressing device 25A to the third pressing device 25C may be, for example, an air cylinder.

[0066] As shown in Figures 10 and 11, the polishing head PH includes a support member 40 that supports the annular pad 11B, a support member 45 that supports the annular pad 11C, and a holding member 150 that holds each of the first pressing device 25A to the third pressing device 25C.

[0067] The support member 40 includes a plurality of frames 40a fixed to the annular pad 11B and a plate 40b to which the frames 40a are fixed. Each of the frames 40a extends parallel to the direction of movement of the annular pad 11B, and the plate 40b extends perpendicular to the frames 40a.

[0068] The second pressing device 25B is connected to the plate 40b. Therefore, when the second pressing device 25B is driven, the biasing force of the second pressing device 25B is transmitted to the annular pad 11B via the support member 40.

[0069] The support member 45 has basically the same structure as the support member 40. The support member 45 includes a plurality of frames 45a fixed to the annular pad 11C and a plate 45b to which the plurality of frames 45a are fixed. Each of the plurality of frames 45a extends parallel to the direction of movement of the annular pad 11C, and the plate 45b extends perpendicular to the plurality of frames 45a.

[0070] The third pressing device 25C is connected to the plate 45b. Therefore, when the third pressing device 25C is driven, the biasing force of the third pressing device 25C is transmitted to the annular pad 11C via the support member 45.

[0071] As shown in FIG. 10, the holding member 150 includes a plurality of rods 150a extending parallel to the frames 40a and 45a, and a plurality of holding members 150b-1, 150b-2, and 150b-3 arranged between the rods 150a.

[0072] The holder 150b-1 holds the first pressing device 25A, the holder 150b-2 holds the second pressing device 25B, and the holder 150b-3 holds the third pressing device 25C.

[0073] For example, if each of the first pressing device 25A to the third pressing device 25C is configured with an air cylinder, the holders 150b-1, 150b-2, and 150b-3 hold a cylinder that houses a rod. With this configuration, the rod of each of the first pressing device 25A to the third pressing device 25C can transmit a biasing force to the pad member 11A and the annular pads 11B and 11C, respectively.

[0074] 12 to 14 are diagrams showing a plurality of pressure areas of the pressure pad structure, in which the illustration of the support members 40, 45 and the holding member 150 is simplified.

[0075] 12 , when the control device 50 operates the first pressing device 25A, the first pressing device 25A presses down the pad member 11A to form a first pressing area against the wafer W. The first pressing area corresponds to the diameter of the pad member 11A. The diameter of the pad member 11A is smaller than the diameter of the wafer W.

[0076] As shown in Figure 13, when the control device 50 operates the first pressing device 25A and the second pressing device 25B, the first pressing device 25A presses down the pad member 11A, and the second pressing device 25B presses down the annular pad 11B via the support member 40.

[0077] The first pressing device 25A and the second pressing device 25B press down on the pad member 11A and the annular pad 11B to form a second pressing area on the wafer W. The second pressing area is larger than the first pressing area (second pressing area > first pressing area) and corresponds to the sum of the first pressing area and the area of ​​the annular portion of the annular pad 11B.

[0078] As shown in FIG. 14, when the control device 50 operates the first pressing device 25A, the second pressing device 25B, and the third pressing device 25C, the first pressing device 25A presses down the pad member 11A, the second pressing device 25B presses down the annular pad 11B via the support member 40, and the third pressing device 25C presses down the annular pad 11C via the support member 45.

[0079] First pressing device 25A, second pressing device 25B, and third pressing device 25C form a third pressing area against wafer W. The third pressing area is larger than the second pressing area (third pressing area > second pressing area) and corresponds to the sum of the second pressing area and the area of ​​the annular portion of annular pad 11C.

[0080] Thus, in this embodiment, the pressure pad structure PS is configured to switch between a first pressure area formed by pressing the pad member 11A against the wafer W, a second pressure area formed by pressing the pad member 11A and the annular pad 11B against the wafer W, and a third pressure area formed by pressing the pad member 11A and the annular pads 11B and 11C against the wafer W.

[0081] 15 is a diagram showing a first polishing target area and a second polishing target area. As shown in FIG. 15, the first polishing target area TA1 is smaller than the second polishing target area TA2. Therefore, when polishing the first polishing target area TA1, the polishing head PH polishes the first polishing target area TA1 while forming a first pressing area with the pressing pad structure PS (more specifically, while pressing down the pad member 11A).

[0082] When polishing a second polishing target area TA2 that is larger than the first polishing target area TA1, the polishing head PH polishes the second polishing target area TA2 while forming a second pressing area (or a third pressing area) using the pressing pad structure PS.

[0083] When the wafer W is polished with the first pressing area formed, the polishing accuracy can be improved, but the amount of polishing per unit time (polishing rate) decreases.When the wafer W is polished with the second pressing area (or the third pressing area) formed, the polishing rate can be increased, but the polishing accuracy decreases.

[0084] When a wafer W is polished with a pressure pad structure PS having a large pressing area for a small target area, the polishing rate increases more than necessary and the polishing precision decreases more than necessary. On the other hand, when a wafer W is polished with a pressure pad structure PS having a small pressing area for a large target area, the polishing rate decreases more than necessary and the polishing precision increases more than necessary.

[0085] According to this embodiment, the polishing head PH can determine an optimum pressing area according to the region to be polished of the wafer W. Therefore, the polishing head PH can realize optimization of the polishing accuracy and the polishing rate.

[0086] In one embodiment, the control device 50 may switch the pressing area of ​​the pressure pad structure PS during polishing of one wafer W. For example, the wafer W may be polished first with a pressure pad structure PS having a large pressing area, and then with a pressure pad structure PS having a small pressing area. By switching in this manner, the polishing head PH can further optimize the polishing accuracy and the polishing rate.

[0087] 16 is a diagram showing a pressure pad structure for supporting a grinding wheel, which is an example of a polishing tool. In the above-described embodiment, the pressure pad structure PS is configured to support a polishing tape PT as the polishing tool, but the pressure pad structure PS may also be configured to support grinding wheels G1 to G3 as the polishing tool.

[0088] 16, grinding wheel G1 is attached to the underside of pad member 11A, grinding wheel G2 is attached to the underside of annular pad 11B, and grinding wheel G3 is attached to the underside of annular pad 11C. Each of grinding wheels G1 to G3 may have the same grit size (grit number) or different grit sizes.

[0089] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims.

[0090] The present invention can be used in a polishing head, a polishing apparatus, and a polishing method.

[0091] REFERENCE SIGNS LIST 1 Stage 2 Stage shaft 3 Stage actuator 11 Pad member 11A Pad member 11B, 11C Annular pad 12 Head rotation mechanism 13 Mounting plate 13a Through hole 14 Shaft 16 Rotary joint 16a Fixed portion 16b Rotating portion 17 Holding base 18A Tape supply reel 18B Tape take-up reel 18C, 18D Guide roller 19 Tape supply mechanism 20 Liquid supply nozzle 25 Pad pressing mechanism 25A First pressing device 25B Second pressing device 25C Third pressing device 26 Head actuator 30 Head swinging mechanism 31 Swing arm 32 Connecting shaft 33 Transmission shaft 35 Drive device 40 Support member 40a Frame 40b Plate 45 Support member 45a Frame 45b Plate 50 Control device 50a Storage device 50b Arithmetic device 150 Holding member 150a Rod body 150b-1 Holding body 150b-2 Holding body 150b-3 Holding body PA Polishing device WH Substrate holding part PT Polishing tape G1 to G3 Grindstone PH Polishing head PS Pressing pad structure PM Pad pressing mechanism CL Central axis A1 Rotational locus A2 Oscillation locus TA Area to be polished TA1 First area to be polished TA2 Second area to be polished

Claims

1. A polishing apparatus comprising: a substrate holding unit that holds a substrate and rotates the substrate at a predetermined rotation angle; a polishing head configured to press a polishing tape against the substrate held by the substrate holding unit; and a head rotation mechanism that rotates the polishing head, wherein the polishing head has a pad member that supports the polishing tape, and the head rotation mechanism is configured to rotate the pad member together with the polishing tape.

2. A polishing apparatus as described in claim 1, wherein the polishing head is equipped with a pad pressing mechanism that applies a pressing force to the pad member to press the polishing tape against the substrate when the head rotation mechanism rotates the polishing tape and the pad member.

3. The polishing device according to claim 1, further comprising a rotary joint that connects the polishing head and the head rotation mechanism, and the polishing head is connected to a rotating part of the rotary joint.

4. The polishing apparatus according to claim 1, wherein said pad member has a diameter smaller than the diameter of said substrate.

5. A polishing head configured to press a polishing tool against a substrate, comprising: a pressure pad structure configured to support the polishing tool and to switch the pressing area against the substrate; and a pad pressing mechanism that applies a pressing force to the pressure pad structure to press the polishing tool against the substrate.

6. The polishing head according to claim 5, wherein the pressure pad structure comprises: a pad member; and an annular pad surrounding the pad member.

7. The polishing head of claim 6, wherein the pressure pad structure is configured to switch the pressure area between a first pressure area formed by pressing the pad member against the substrate and a second pressure area formed by pressing the pad member and the annular pad against the substrate.

8. A polishing head as described in claim 7, wherein the pad pressing mechanism comprises: a first pressing device connected to the pad member; and a second pressing device connected to the annular pad, wherein the first pressing device forms the first pressing area by pressing the pad member against the substrate, and the first pressing device and the second pressing device form the second pressing area by pressing the pad member and the annular pad against the substrate.

9. The polishing head according to claim 5, wherein the polishing tool corresponds to a polishing tape or a grinding stone supported on the pressure pad structure.

10. A polishing apparatus comprising: a substrate holding section that holds a substrate and rotates the substrate at a predetermined rotation angle; and a polishing head according to any one of claims 5 to 9 that is configured to press a polishing tool against the substrate held by the substrate holding section.

11. The polishing apparatus according to claim 10, further comprising a head rotation mechanism for rotating the polishing head, the head rotation mechanism being configured to rotate the pressure pad structure together with the polishing tool.

12. A polishing method comprising: a step of holding a substrate and rotating the substrate at a predetermined rotation angle; and a step of pressing a polishing tape supported by a pad member of a polishing head against the substrate, wherein the step of pressing the polishing tape against the substrate comprises a step of pressing the polishing tape against the substrate while rotating the pad member together with the polishing tape.

13. A polishing method comprising: a step of holding a substrate and rotating the substrate at a predetermined rotation angle; and a step of pressing a polishing tool supported by a pressure pad structure of a polishing head against the substrate, wherein the step of pressing the polishing tool against the substrate includes a step of switching the pressing area against the substrate by the pressure pad structure.

14. A polishing method as described in claim 13, wherein the pressure pad structure comprises: a pad member; and an annular pad surrounding the pad member; and the step of pressing the polishing tool against the substrate includes a step of switching the pressure area between a first pressure area formed by pressing the pad member against the substrate and a second pressure area formed by pressing the pad member and the annular pad against the substrate.

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