Polishing apparatus, polishing method, and polishing head

Abstract

To provide a polishing apparatus capable of removing chipping.SOLUTION: A polishing apparatus includes a first polishing head and a second polishing head. The first polishing head presses a first polishing tool against a peripheral portion of a substrate to form a recess in the peripheral portion, and the second polishing head presses a second polishing tool against a polishing boundary portion of the recess.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In recent years, in order to achieve even higher density and higher performance in semiconductor devices, progress has been made in the development of three-dimensional packaging technology, which stacks multiple substrates to integrate them three-dimensionally. In three-dimensional packaging technology, for example, the device surface of a first substrate on which integrated circuits and electrical wiring are formed is bonded to the device surface of a second substrate on which integrated circuits and electrical wiring are formed.

[0003] After bonding the first substrate to the second substrate, the first substrate is thinned using a polishing or grinding device. In this manner, integrated circuits can be stacked in a direction perpendicular to the device surfaces of the first and second substrates. In this specification, the form of multiple substrates bonded together may be referred to as a "laminated substrate" or a "composite substrate." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-037585 [Patent Document 2] Japanese Patent Publication No. 2022-037426 Summary of the Invention [Problem to be solved by the invention]

[0005] Typically, the peripheral edge of a substrate is polished to a rounded shape in advance, and grinding a first substrate having such a rounded peripheral edge results in a sharp edge (knife edge) being formed on the first substrate.

[0006] Such knife-edge portions are easily chipped by physical contact. Furthermore, there is a risk that the knife-edge portions may cause damage to the laminated substrate itself when the laminated substrate is transported. Therefore, to prevent the formation of knife-edge portions, a polishing tool (e.g., polishing tape) is pressed against the peripheral edge of the laminated substrate while rotating the laminated substrate to remove the peripheral edge of the first substrate and form a depression in the peripheral edge of the laminated substrate.

[0007] However, forming such a depression may result in chipping at the polishing boundary of the depression, which may cause defects in the laminated substrate and therefore must be removed.

[0008] Such a problem is not necessarily limited to laminated substrates (i.e., composite substrates). For example, even in a single substrate that is not a laminated substrate, forming a recess may cause chipping at the polishing boundary of the recess. Therefore, even in a single substrate, it is necessary to remove chipping.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a polishing apparatus, a polishing method, and a polishing head that are capable of removing chipping. [Means for solving the problem]

[0010] In one embodiment, a polishing apparatus is provided, comprising: a first polishing head holding a first polishing tool having a first angle as an acute angle; and a second polishing head holding a second polishing tool having a second angle as a right angle or an obtuse angle, wherein the first polishing head presses the first polishing tool against a peripheral edge of a substrate to form a recess in the peripheral edge, and the second polishing head presses the second polishing tool against a polishing boundary of the recess.

[0011] In one embodiment, the first polishing head corresponds to a rough polishing head that presses a rough polishing tape as the first polishing tool against the peripheral portion to form a recess in the peripheral portion, and the second polishing head corresponds to a finish polishing head that presses a finish polishing tape as the second polishing tool against the polishing boundary portion, and the rough polishing head supports the rough polishing tape so that the tape angle of the rough polishing tape is the first angle, and the finish polishing head supports the finish polishing tape so that the tape angle of the finish polishing tape is the second angle. In one aspect, each of the rough polishing head and the finish polishing head includes a pressing member for pressing the rough polishing tape and the finish polishing tape against the peripheral portion, a immediately preceding guide roller arranged upstream of the pressing member in the conveying direction of the rough polishing tape and the finish polishing tape, and adjacent to the pressing member, and a immediately preceding guide roller actuator for moving the immediately preceding guide roller. In one aspect, the front-most guide roller actuator is configured to move the front-most guide roller in a direction approaching the pressing member and a direction away from the pressing member.

[0012] In one embodiment, the polishing apparatus is equipped with an operation control unit that controls the operation of the immediately preceding guide roller actuator, and the operation control unit operates the immediately preceding guide roller actuator to move the immediately preceding guide roller until the tape angle of the rough polishing tape becomes the first angle, and operates the immediately preceding guide roller actuator to move the immediately preceding guide roller until the tape angle of the finish polishing tape becomes the second angle. In one embodiment, the operation control unit operates the immediately preceding guide roller actuator to move the rough polishing tape in the depth direction of the substrate while the tape angle is at the first angle, thereby forming a recess having a predetermined depth in the peripheral portion, and operates the immediately preceding guide roller actuator to set the tape angle to the second angle, thereby pressing the finish polishing tape against the polishing boundary portion. In one aspect, the operation control section operates the immediately preceding guide roller actuator to press the finish polishing tape in a region located between the immediately preceding guide roller and the pressing member against the polishing boundary section.

[0013] In one embodiment, each of the rough polishing head and the finish polishing head is equipped with a leading guide roller arranged upstream of the immediately preceding guide roller in the respective conveying directions of the rough polishing tape and the finish polishing tape, and adjacent to the immediately preceding guide roller, and a leading guide roller actuator that moves the leading guide roller, and the leading guide roller actuator moves the leading guide roller until it reaches a third angle greater than the second angle. In one embodiment, the polishing apparatus is equipped with an operation control unit that controls the operation of the leading guide roller actuator, and the operation control unit operates the immediately preceding guide roller actuator to press the finishing polishing tape against the polishing boundary portion, and then operates the leading guide roller actuator to move the leading guide roller until the tape angle becomes the third angle. In one embodiment, the first grinding head holds a first grinding stone as the first grinding tool, and the second grinding head holds a second grinding stone as the second grinding tool, the first grinding stone having a tapered concave portion that forms the first angle, and the second grinding stone having a tapered convex portion that forms the second angle.

[0014] In one embodiment, a polishing method is provided, which includes pressing a first polishing tool having a first acute angle against a peripheral edge of a substrate by a first polishing head to form a recess in the peripheral edge, and pressing a second polishing tool having a second right or obtuse angle against a polishing boundary of the recess by a second polishing head.

[0015] In one embodiment, the first polishing head corresponds to a rough polishing head that presses a rough polishing tape as the first polishing tool against the peripheral portion to form a recess in the peripheral portion, and the second polishing head corresponds to a finish polishing head that presses a finish polishing tape as the second polishing tool against the polishing boundary portion, and sets the tape angle of the rough polishing tape to the first angle to press the rough polishing tape against the peripheral portion to form a recess in the peripheral portion, and sets the tape angle of the finish polishing tape to the second angle to press the finish polishing tape against the polishing boundary portion. In one embodiment, a immediately preceding guide roller arranged upstream of the pressing member and adjacent to the pressing member in each conveying direction of the rough polishing tape and the finish polishing tape is operated to set the tape angle to the first angle, and the immediately preceding guide roller is operated to set the tape angle to the second angle. In one embodiment, a leading guide roller positioned upstream of the immediately preceding guide roller and adjacent to the immediately preceding guide roller in the respective conveying directions of the rough polishing tape and the finish polishing tape is operated to set the tape angle to a third angle greater than the second angle. In one embodiment, the first grinding head holds a first grinding stone as the first grinding tool, and the second grinding head holds a second grinding stone as the second grinding tool, and the first grinding stone having a tapered concave portion forming the first angle is pressed against the peripheral portion to form a depression in the peripheral portion, and the second grinding stone having a tapered convex portion forming the second angle is pressed against the grinding boundary portion.

[0016] In one embodiment, a polishing head is provided, the polishing head including a pressing member for pressing the polishing tape against the peripheral portion, a front guide roller disposed upstream of the pressing member in a conveying direction of the polishing tape and adjacent to the pressing member, and a front guide roller actuator for moving the front guide roller, the front guide roller actuator moving the front guide roller until the tape angle of the polishing tape becomes a first acute angle, and then moving the front guide roller until the tape angle becomes a second right angle or an obtuse angle.

[0017] In one aspect, the front-most guide roller actuator is configured to move the front-most guide roller in a direction approaching the pressing member and a direction away from the pressing member. In one embodiment, the polishing head moves the polishing tape in the depth direction of the substrate while the tape angle is set to the first angle by the immediately preceding guide roller actuator, forming a recess having a predetermined depth in the peripheral portion, and then uses the immediately preceding guide roller actuator to set the tape angle to a second angle, pressing the polishing tape against the polishing boundary portion of the recess. In one embodiment, the polishing head includes a leading guide roller positioned upstream of the immediately preceding guide roller in the conveying direction of the polishing tape and adjacent to the immediately preceding guide roller, and a leading guide roller actuator that moves the leading guide roller, and the leading guide roller actuator moves the leading guide roller until the tape angle becomes a third angle greater than the second angle. [Effects of the Invention]

[0018] According to the above means, the polishing apparatus can remove chipping. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a side view showing the peripheral portion of a composite substrate to be polished. [Figure 2] FIG. 1 illustrates an embodiment of a polishing apparatus. [Figure 3] 3(a) and 3(b) are diagrams showing a front guide roller actuator that moves the front guide roller. [Figure 4] 4(a) and 4(b) are diagrams showing a leading guide roller actuator that moves the leading guide roller. [Figure 5] 5(a) to 5(d) are diagrams showing the polishing process of the first wafer. [Figure 6] 5A to 5C are diagrams showing a flow of polishing a first wafer by the polishing apparatus. [Figure 7] FIG. 10 is a diagram showing the polishing boundary of the depression. [Figure 8] FIG. 10 is a diagram showing a polishing head that removes chippings using a polishing tape. [Figure 9] FIG. 10 is a diagram showing another embodiment of the polishing apparatus. [Figure 10A] FIG. 10 is a diagram showing another embodiment of the polishing apparatus. [Figure 10B] FIG. 10 is a diagram showing another embodiment of the polishing apparatus. [Figure 10C] FIG. 10 is a view showing a pressing member having a first angle. [Figure 10D] FIG. 10 is a view showing a pressing member having a second angle. [Figure 11] FIG. 10 is a diagram showing another embodiment of the polishing apparatus. [Figure 12] FIG. 12(a) is a diagram showing a grinding wheel having a tapered recess, and FIG. 12(b) is a diagram showing a grinding wheel having a tapered protrusion. [Figure 13] 13(a) to 13(c) are diagrams showing the process of polishing the peripheral edge of the wafer. [Figure 14] 14(a) and 14(b) are diagrams showing the manufacturing process of a composite wafer. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] Fig. 1 is a side view showing the peripheral edge of a composite substrate to be polished. As shown in Fig. 1, the composite substrate W has a structure in which a first substrate W1 and a second substrate W2 are stacked one on top of the other. The first substrate W1 is a device substrate (or device wafer) having a device layer 200 on which a circuit pattern or the like is formed.

[0022] The second substrate W2 is a support substrate (or support wafer) for supporting the first substrate W1. The device layer 200 faces the second substrate W2. The first substrate W1 and the second substrate W2 are bonded together with or without an adhesive.

[0023] A circular wafer is an example of a substrate, and the substrate to be polished in the present invention is not limited to a circular wafer. In the embodiments described below, a wafer is used as an example of a substrate. Therefore, in the following description, the composite substrate W will be referred to as a composite wafer W, the first substrate W1 will be referred to as a first wafer W1, and the second substrate W2 will be referred to as a second wafer W2, but it is not intended that the present invention be limited to the embodiments described below.

[0024] Fig. 2 is a diagram showing one embodiment of a polishing apparatus. As shown in Fig. 2, the polishing apparatus includes a substrate holding device 3 configured to hold and rotate a composite wafer W, a first polishing head 22A and a second polishing head 22B configured to polish the peripheral portion of a first wafer W1 to form a recess in the peripheral portion of the composite wafer W, and an operation control unit 10 that controls the operation of the substrate holding device 3 and the polishing heads 22A and 22B.

[0025] The substrate holding device 3 includes a holding stage 12 having a substrate holding surface 12a for holding the composite wafer W, a stage rotation device 15 for rotating the holding stage 12 around the axis CL of the substrate holding surface 12a, and a stage axis 17 fixed to the bottom of the holding stage 12.

[0026] The holding stage 12 has openings 12b, such as holes or grooves, formed in the substrate holding surface 12a. The openings 12b are connected to a vacuum line 16. The holding stage 12 may have a plurality of openings 12b. When a vacuum is formed in the openings 12b through the vacuum line 16 with the composite wafer W placed on the substrate holding surface 12a, the composite wafer W is held to the substrate holding surface 12a by the vacuum.

[0027] The substrate holding surface 12a has the same contour shape as the composite wafer W. In this embodiment, the composite wafer W is circular, and the substrate holding surface 12a is also circular. The substrate holding surface 12a has the same size as the composite wafer W. That is, the diameter of the substrate holding surface 12a is the same as the diameter of the composite wafer W. Therefore, the entire lower surface of the composite wafer W is held by the substrate holding surface 12a.

[0028] In one embodiment, the substrate holding surface 12a may be smaller than the composite wafer W, as long as it can support the peripheral edge of the composite wafer W. In one embodiment, the substrate holding surface 12a may be larger than the composite wafer W.

[0029] The stage rotation device 15 is equipped with an electric motor and is connected to a stage shaft 17. When the stage rotation device 15 is driven, the holding stage 12 and the stage shaft 17 rotate together about the axis CL of the substrate holding surface 12a.

[0030] The composite wafer W is held on the substrate holding surface 12a so that the axis of the composite wafer W coincides with the axis CL of the substrate holding surface 12a. Therefore, the composite wafer W rotates integrally with the holding stage 12 around the axis of the composite wafer W (i.e., the axis CL of the substrate holding surface 12a).

[0031] The polishing apparatus includes a liquid supply nozzle 18 disposed above the substrate holding surface 12a. The liquid supply nozzle 18 is connected to a liquid supply line (not shown) and is configured to supply a liquid such as pure water or functional water to the center of the composite wafer W.

[0032] The functional water is a water-containing acidic liquid, alkaline liquid, ozone water, fine bubble water, etc. The liquid supplied to the center of the rotating composite wafer W spreads over the entire upper surface of the composite wafer W by centrifugal force, washing away polishing debris.

[0033] Each of the polishing heads 22A, 22B is equipped with a pressing member 21 for pressing each of the polishing tapes T1, T2, which are examples of polishing tools, against the peripheral edge of the composite wafer W on the substrate holding surface 12a, and a moving actuator 23 for moving the pressing member 21 in a direction perpendicular to the substrate holding surface 12a.

[0034] In this embodiment, the polishing head 22A is a rough polishing head that supports a rough polishing tape T1 having abrasive grains on its surface. The polishing head 22B is a finish polishing head that supports a finish polishing tape T2 having abrasive grains on its surface that are smaller in particle size than the abrasive grains of the rough polishing tape T1. Hereinafter, in this specification, the rough polishing tape T1 and the finish polishing tape T2 may be simply referred to as the polishing tape T without any particular distinction being made between them.

[0035] In this embodiment, the first polishing head 22A and the second polishing head 22B have the same configuration, and therefore, in this specification, the polishing heads 22A and 22B may be simply referred to as the polishing head 22 without being distinguished from each other.

[0036] The polishing head 22 is disposed above the outer periphery of the substrate holding surface 12a. The movement actuator 23 is held by a holding member such as a bracket (not shown). The specific configuration of the movement actuator 23 is not particularly limited, but examples of the movement actuator 23 include an air cylinder or a combination of a ball screw mechanism and a servo motor.

[0037] The polishing head 22 includes a supply reel 26 that supplies the polishing tape T, a take-up reel 27 that takes up the polishing tape T, and a tape feed mechanism 30 that feeds the polishing tape T in its longitudinal direction (i.e., the conveying direction). The movement actuator 23 is configured to move the supply reel 26, the take-up reel 27, the pressing member 21, and the tape feed mechanism 30 together.

[0038] The pressing member 21 is disposed above the outer periphery of the substrate holding surface 12a. The pressing member 21 is located directly above the peripheral edge of the composite wafer W held on the substrate holding surface 12a. The pressing member 21 supports the back side of the polishing tape T and presses the polishing surface (front side) of the polishing tape T against the peripheral edge of the composite wafer W, thereby polishing the peripheral edge of the first wafer W1.

[0039] The movement actuator 23 moves the pressing member 21 toward the peripheral edge of the composite wafer W. By moving, the pressing member 21 can press the polishing tape T against the peripheral edge of the first wafer W1.

[0040] The force with which the pressing member 21 presses the polishing tape T against the peripheral edge of the first wafer W1 (i.e., the polishing load) can be adjusted by the moving actuator 23. The polishing tape T at the polishing point of the composite wafer W extends in the radial direction of the composite wafer W (i.e., the radial direction of the substrate holding surface 12a).

[0041] 2, the polishing head 22 includes a sensor target 32 ​​and a displacement sensor 33 arranged facing the sensor target 32. The sensor target 32 ​​can be moved integrally with the pressing member 21 by a movement actuator 23.

[0042] The displacement sensor 33 is configured to detect the movement distance of the sensor target 32, that is, the movement distance of the pressing member 21. Examples of the displacement sensor 33 include a contact displacement sensor and a non-contact displacement sensor.

[0043] The displacement sensor 33 is electrically connected to the operation control unit 10. The displacement sensor 33 detects a signal corresponding to the movement distance of the pressing member 21 while polishing the peripheral portion of the first wafer W1. The movement distance of the pressing member 21 is the movement distance from the initial position of the pressing member 21 in a direction perpendicular to the substrate holding surface 12a. In one example, the initial position may be the position of the pressing member 21 when the pressing member 21 brings the polishing tape T into contact with the upper surface of the first wafer W1 while the composite wafer W is not rotating.

[0044] The operation control unit 10 includes a storage device 10a storing a program, and a processing device 10b that executes calculations according to instructions contained in the program. The processing device 10b includes a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) that executes calculations according to instructions contained in the program stored in the storage device 10a.

[0045] The storage device 10a includes a main storage device (e.g., random access memory) accessible by the processing device 10b, and an auxiliary storage device (e.g., a hard disk drive or solid state drive) for storing data and programs. The operation control unit 10 is composed of at least one computer.

[0046] The displacement sensor 33 is configured to send a signal corresponding to the movement distance of the pressing member 21 to the operation control unit 10. The operation control unit 10 is configured to measure the movement distance of the pressing member 21 based on the signal sent from the displacement sensor 33, and to determine the polishing endpoint of the first wafer W1 based on the measured movement distance. In this embodiment, the movement distance of the pressing member 21 corresponds to the movement distance of the polishing head 22.

[0047] 3(a) and 3(b) are diagrams showing a previous guide roller actuator that moves the previous guide roller. The polishing head 22 is disposed upstream of the pressing member 21 in the conveyance direction of the polishing tape T and is equipped with a previous guide roller 36 disposed adjacent to the pressing member 21, and a previous guide roller actuator 300 that moves the previous guide roller 36.

[0048] The immediately preceding guide roller 36 is configured to support the polishing tape T being transported from the supply reel 26 to the take-up reel 27. The pressing member 21 has a pressing surface 21A parallel to the substrate holding surface 12a and an inclined surface 21B connected to the pressing surface 21A. The pressing surface 21A forms the bottom surface of the pressing member 21. The inclined surface 21B faces the axis CL of the substrate holding surface 12a and forms the inner surface of the pressing member 21.

[0049] The immediately preceding guide roller 36 determines the relative position of the polishing tape T with respect to the inclined surface 21B of the pressing member 21. The immediately preceding guide roller actuator 300 is configured to move the immediately preceding guide roller 36 until the tape angle of the polishing tape T becomes the first angle θ1, and to move the immediately preceding guide roller 36 until the tape angle becomes the second angle θ2.

[0050] The tape angle is defined as the angle formed by the polishing tape T in the area AR1 facing the pressing surface 21A and the polishing tape T in the area AR2 facing the inclined surface 21B. The area AR2 corresponds to the area located between the immediately preceding guide roller 36 and the inclined surface 21B of the pressing member 21.

[0051] In this embodiment, the first angle θ1 is an acute angle, and the second angle θ2 is an obtuse angle. In one embodiment, the second angle θ2 may be a right angle. That is, the second angle θ2 is a right angle or an obtuse angle.

[0052] A combination of a ball screw mechanism and a servo motor is one example of the immediately preceding guide roller actuator 300. For example, the immediately preceding guide roller 36 is connected to a ball screw mechanism (not shown) and configured to be movable by driving the servo motor (not shown).

[0053] The operation control unit 10 is electrically connected to the immediately preceding guide roller actuator 300 and is configured to control the operation of the immediately preceding guide roller actuator 300. The operation control unit 10 operates the immediately preceding guide roller actuator 300 to move the immediately preceding guide roller 36 in the horizontal direction (i.e., the direction parallel to the substrate holding surface 12a).

[0054] When the immediately preceding guide roller actuator 300 moves the immediately preceding guide roller 36 in a direction approaching the pressing member 21 (i.e., the approach direction), the immediately preceding guide roller 36 moves the polishing tape T and determines the tape angle to the first angle θ1 (see Figure 3(a)).

[0055] When the immediately preceding guide roller actuator 300 moves the immediately preceding guide roller 36 in a direction away from the pressing member 21 (i.e., in the separating direction), the immediately preceding guide roller 36 moves the polishing tape T and determines the tape angle to be the second angle θ2 (see FIG. 3(b)). In this embodiment, the second angle θ2 is an angle within a range of approximately 100 to 110 degrees.

[0056] The polishing head 22 includes an immediate rear guide roller 38 disposed downstream of the pressing member 21 in the transport direction of the polishing tape T. The tape feed mechanism 30 is disposed downstream of the immediate rear guide roller 38 (see FIG. 2).

[0057] The tape feeding mechanism 30 is configured to feed the polishing tape T from the supply reel 26 toward the take-up reel 27 at a predetermined speed during polishing of the composite wafer W. In one embodiment, the polishing head 22 does not necessarily have to include the tape feeding mechanism 30, and may be configured to feed the polishing tape T by a tension motor (not shown) connected to the take-up reel 27.

[0058] The polishing head 22 is disposed upstream of the immediately preceding guide roller 36 in the conveying direction of the polishing tape T, and is equipped with a leading guide roller 37 disposed adjacent to the immediately preceding guide roller 36. The leading guide roller 37 is disposed downstream of the supply reel 26. Therefore, the polishing tape T extends from the supply reel 26, passing through the leading guide roller 37, the immediately preceding guide roller 36, the immediately succeeding guide roller 38, and the tape feed mechanism 30 in this order, to the take-up reel 27.

[0059] 4(a) and 4(b) are diagrams showing a leading guide roller actuator that moves the leading guide roller. The polishing head 22 may include a leading guide roller actuator 301 that moves the leading guide roller 37.

[0060] The leading guide roller actuator 301 may have the same structure as the immediately preceding guide roller actuator 300. An example of the leading guide roller actuator 301 is a combination of a ball screw mechanism and a servo motor. For example, the leading guide roller 37 is connected to a ball screw mechanism (not shown) and configured to be movable by driving a servo motor (not shown).

[0061] The operation control unit 10 is electrically connected to the leading guide roller actuator 301 and is configured to control the operation of the leading guide roller actuator 301. The operation control unit 10 operates the leading guide roller actuator 301 to move the leading guide roller 37 in the horizontal direction.

[0062] After the immediately preceding guide roller actuator 300 operates the immediately preceding guide roller 36 to set the tape angle to the second angle θ2 (see FIG. 4(a)), the preceding guide roller actuator 301 moves the preceding guide roller 37 in the separation direction (see FIG. 4(b)). At this time, the immediately preceding guide roller actuator 300 operates the immediately preceding guide roller 36 to a position where the immediately preceding guide roller 36 does not contact the polishing tape T.

[0063] In this way, the leading guide roller 37 moves the polishing tape T to set the tape angle to a third angle θ3 that is larger than the second angle θ2. The third angle θ3 is an obtuse angle that is larger than the second angle θ2. In this way, the leading guide roller actuator 301 may move the leading guide roller 37 in the separation direction until the tape angle reaches the third angle θ3.

[0064] 5(a) to 5(d) are diagrams showing the polishing process of the first wafer. Fig. 6 is a diagram showing the flow of polishing the first wafer by the polishing apparatus. The first wafer W1 is polished as follows.

[0065] First, the composite wafer W is placed on the substrate holding surface 12a by a transfer device (not shown) so that its center coincides with the axis CL of the substrate holding surface 12a. When the operation control unit 10 drives the stage rotation device 15, the stage rotation device 15 rotates the holding stage 12 about the axis CL, and the composite wafer W rotates together with the holding stage 12.

[0066] The liquid supply nozzle 18 supplies liquid to the center of the first wafer W1, forming a liquid film on the upper surface of the first wafer W1. When the operation control unit 10 drives the movement actuator 23, the movement actuator 23 moves the entire polishing head 22A including the pressing member 21 toward the first wafer W1.

[0067] The pressing member 21 presses the polishing surface of the rough polishing tape T1 against the peripheral edge of the first wafer W1 (see FIG. 5(a) and step S101 in FIG. 6). More specifically, the pressing member 21 presses the rough polishing tape T1 in the area AR1 against the peripheral edge of the first wafer W1.

[0068] At this time, the operation control unit 10 polishes the peripheral edge of the first wafer W1 by moving the pressing member 21 in the depth direction of the composite wafer W with the tape angle set to the first angle θ1 by the immediately preceding guide roller actuator 300. The direction in which the pressing member 21 presses the rough polishing tape T1 against the peripheral edge of the first wafer W1 is perpendicular to the top surface of the first wafer W1, which corresponds to the depth direction of the composite wafer W (see FIG. 5(b)).

[0069] The peripheral edge of the first wafer W1 is polished by relative movement between the rough polishing tape T1 and the first wafer W1 in the presence of a liquid. During polishing of the first wafer W1, the rough polishing tape T1 is fed in its conveying direction (i.e., longitudinal direction) at a predetermined speed.

[0070] During polishing of the first wafer W1, the displacement sensor 33 detects a signal corresponding to the movement distance of the pressing member 21. The operation control unit 10 measures the movement distance of the pressing member 21 based on the signal sent from the displacement sensor 33. The operation control unit 10 determines the polishing endpoint, which is the point at which the movement distance of the pressing member 21 reaches a preset target value. In other words, the operation control unit 10 determines whether polishing of the first wafer W1 has finished based on the signal obtained from the displacement sensor 33 (see step S102 in FIG. 6).

[0071] If the operation control unit 10 determines that polishing of the first wafer W1 has not been completed (see "NO" in step S102), the operation control unit 10 continues polishing of the first wafer W1. On the other hand, if the operation control unit 10 determines that polishing of the first wafer W1 has been completed (see "YES" in step S102), the operation control unit 10 ends polishing of the first wafer W1. In this way, the polishing head 22A forms a recess 160 having a predetermined depth in the peripheral portion of the composite wafer W (see FIG. 5(c)).

[0072] In this embodiment, the operation control unit 10 determines the polishing endpoint of the first wafer W1 based on a signal sent from the displacement sensor 33. However, in another embodiment, the operation control unit 10 may determine the polishing endpoint of the first wafer W1 based on the polishing time. In this case, the operation control unit 10 determines the end of polishing of the first wafer W1 when a predetermined polishing time has elapsed.

[0073] Fig. 7 is a diagram showing the polishing boundary of a recess. As shown in Fig. 7, when a recess 160 is formed on the peripheral edge of the composite wafer W, a chipping CH may occur at the polishing boundary PB of the recess 160. The polishing boundary PB is defined as the boundary between the polished area of ​​the first wafer W1 polished by the polishing head 22A and the unpolished area of ​​the first wafer W1 that has not been polished.

[0074] After determining the polishing endpoint, the operation control unit 10 operates the movement actuator 23 of the polishing head 22A to move the polishing head 22A, including the pressing member 21, in a direction away from the first wafer W1. Thereafter, the operation control unit 10 operates the movement actuator 23 of the polishing head 22B to move the entire polishing head 22B, including the pressing member 21, toward the first wafer W1.

[0075] At this time, the operation control unit 10 operates the immediately preceding guide roller actuator 300 to press the finish polishing tape T2 against the polishing boundary portion PB of the recess 160 with the tape angle set to the second angle θ2 (see FIG. 5(d) and step S103 in FIG. 6). More specifically, the polishing head 22B presses the finish polishing tape T2 in the area AR2 against the polishing boundary portion PB.

[0076] The operation control unit 10 may move the polishing head 22B to a predetermined polishing position adjacent to the recess 160, and then operate the immediately preceding guide roller actuator 300 to determine the tape angle to the second angle θ2, or may move the polishing head 22B to the predetermined polishing position after determining the tape angle to the second angle θ2.

[0077] 8 is a diagram showing a polishing head that removes chippings using a polishing tape. As shown in FIG. 8, the polishing head 22B is configured to remove chippings CH by pressing the finish polishing tape T2 against the chippings CH formed in the polishing boundary portion PB. In particular, by removing the chippings CH with the finish polishing tape T2 in the area AR2, it is possible to prevent the finish polishing tape T2 from breaking.

[0078] If the finish polishing tape T2 is moved in the depth direction of the composite wafer W and pressed against the chipping CH in the area AR1, the finish polishing tape T2 may come into contact with the chipping CH at the corner of the polishing boundary PB and be cut. In other words, the finish polishing tape T2 in the area AR1 may be pinched between the pressing surface 21A of the pressing member 21 and the chipping CH at the polishing boundary PB and be cut.

[0079] In this embodiment, the finish polishing tape T2 is elastically deformed toward the inclined surface 21B of the pressing member 21 by pressing the finish polishing tape T2 in the area AR2 against the chipping CH.

[0080] More specifically, by pressing the finish polishing tape T2 against the chipping CH with the tape angle set to the second angle θ2, a gap is formed between the finish polishing tape T2 and the inclined surface 21B of the pressing member 21 in the area AR2. Therefore, the finish polishing tape T2 can elastically deform toward the inclined surface 21B. With this configuration, the polishing head 22B can prevent the finish polishing tape T2 from being cut.

[0081] After step S103 in FIG. 6, the operation control unit 10 determines whether polishing of the first wafer W1 is completed based on the polishing time required to remove the chipping CH (i.e., the chipping removal time) (see step S104 in FIG. 6).

[0082] If the operation control unit 10 determines that the chipping removal time has not elapsed (see "NO" in step S104 of FIG. 6), it continues removing the chipping CH. On the other hand, if the operation control unit 10 determines that the chipping removal time has elapsed (see "YES" in step S104 of FIG. 6), it decides to end the removal of the chipping CH.

[0083] In one embodiment, the operation control unit 10 may operate the leading guide roller actuator 301 to determine the tape angle to the third angle θ3 and additionally remove chippings CH. For example, if chippings CH at the polishing boundary portion PB are formed over a wide area in the radial direction of the composite wafer W, the operation control unit 10 can reliably remove chippings CH formed over a wide area by moving the leading guide roller 37 in the separation direction using the leading guide roller actuator 301 until the tape angle becomes the third angle θ3.

[0084] Fig. 9 is a diagram showing another embodiment of the polishing apparatus. In the above-described embodiment, the polishing heads 22A and 22B have the same configuration, but in the embodiment shown in Fig. 9, the polishing heads 22A and 22B have different configurations.

[0085] 9, the polishing head 22A is configured to support the rough polishing tape T1 so that the tape angle is a first angle θ1, and the polishing head 22B is configured to support the finish polishing tape T2 so that the tape angle is a second angle θ2.

[0086] In this case, there is no need to change the tape angle between the first angle θ1 and the second angle θ2. Therefore, in the embodiment shown in Figure 9, neither of the polishing heads 22A, 22B includes a immediately preceding guide roller actuator 300 (and a leading guide roller actuator 301).

[0087] In this way, as long as the polishing apparatus is equipped with a polishing head 22A that forms a recess 160 on the peripheral edge of the composite wafer W and a polishing head 22B that removes chipping CH formed in the recess 160, the polishing heads 22A and 22B do not necessarily have to be equipped with a immediately preceding guide roller actuator 300 (and a preceding guide roller actuator 301).

[0088] 10A is a diagram showing another embodiment of the polishing apparatus. In the above-described embodiment, the polishing apparatus includes multiple polishing heads 22A and 22B. However, as shown in FIG. 10A, the polishing apparatus may include a single polishing head 22.

[0089] In the above-described embodiment, the polishing head 22A supports a rough polishing tape T1 for forming a recess 160 on the peripheral edge of the composite wafer W, and the polishing head 22B supports a finish polishing tape T2 for removing chipping CH formed in the recess 160.

[0090] However, depending on the polishing conditions, such as the type (e.g., hardness) of the composite wafer W to be polished, the polishing apparatus does not necessarily need to be equipped with multiple polishing heads 22A, 22B that separately support the two types of polishing tapes T1, T2, but may be equipped with a single polishing head 22. In this case, the polishing apparatus is configured to operate the polishing head 22 to form a recess 160 on the peripheral edge of the composite wafer W and to remove chippings CH formed in the recess 160.

[0091] The polishing head 22 in the embodiment shown in Fig. 10A has the same structure as the polishing heads 22A and 22B described with reference to Figs. 1 to 8. Therefore, the polishing head 22 includes a pressing member 21, a preceding guide roller 36, and a preceding guide roller actuator 300. In one embodiment, the polishing head 22 may further include a leading guide roller actuator 301 that moves the leading guide roller 37 (see Fig. 4(b)).

[0092] FIG. 10B illustrates another embodiment of the polishing apparatus. As shown in FIG. 10B, the polishing apparatus may be configured to polish a single wafer W rather than a composite wafer W. In one embodiment, similar to the embodiments described above, the polishing apparatus may be configured to polish a composite wafer W in the embodiment illustrated in FIG. 10B. In the embodiments illustrated in FIGS. 2 through 10A, the polishing apparatus may be configured to polish a single wafer W rather than a composite wafer W.

[0093] In the embodiment shown in FIG. 10B, the polishing apparatus includes pressing members 210A and 210B having different shapes. Specifically, the polishing head 22A includes a pressing member 210A having a first angle θα as an acute angle. The polishing head 22B includes a pressing member 210B having a second angle θβ as an obtuse angle. In the embodiment shown in FIG. 10B, the second angle θβ is an obtuse angle, but it may also be a right angle. Hereinafter, in this specification, the pressing members 210A and 210B may be simply referred to as pressing members 210 without any particular distinction.

[0094] 10C is a diagram showing a pressing member having a first angle. As shown in FIG. 10C, the pressing member 210A has a pressing surface 210A-1 parallel to the substrate holding surface 12a and an inclined surface 210A-2 connected to the pressing surface 210A-1.

[0095] The first angle θα is the angle between the pressing surface 210A-1 and the inclined surface 210A-2. The polishing head 22A positions the polishing tape T so that it is aligned with the pressing surface 210A-1 and the inclined surface 210A-2, thereby determining the tape angle to be the first angle θα.

[0096] 10D is a diagram showing a pressing member having a second angle. As shown in FIG. 10D, the pressing member 210B has a pressing surface 210B-1 parallel to the substrate holding surface 12a and an inclined surface 210B-2 connected to the pressing surface 210B-1.

[0097] The second angle θβ is the angle between the pressing surface 210B-1 and the inclined surface 210B-2. The polishing head 22B positions the polishing tape T along the pressing surface 210B-1 and the inclined surface 210B-2, thereby determining the tape angle to be the second angle θβ.

[0098] With this configuration, the polishing head 22 does not need to change the tape angle between the first angle θα and the second angle θβ. Therefore, in the embodiment shown in Figures 10B to 10D, neither the polishing head 22A nor 22B needs to include the immediately preceding guide roller actuator 300 (and the leading guide roller actuator 301).

[0099] 2 to 10A, the polishing tool corresponds to the polishing tape T, while in the embodiment shown in Figures 10B to 10D, the polishing tool corresponds to the combination of the polishing tape T and the pressing member 210. Specifically, the polishing tool having the first angle θα corresponds to the combination of the polishing tape T and the pressing member 210A, and the polishing tool having the second angle θβ corresponds to the combination of the polishing tape T and the pressing member 210B.

[0100] Thus, in the above-described embodiment (see FIGS. 1 to 10D), the polishing head 22A is configured to hold a polishing tool (polishing tape T, or a combination of polishing tape T and pressing member 210) having a first angle as an acute angle, and is configured to press such a polishing tool against the peripheral edge of the wafer W (a single wafer W or composite wafer W) to form a recess in the peripheral edge. The polishing head 22B is configured to hold a polishing tool (polishing tape T) having a second angle as a right angle or obtuse angle, and is configured to press such a polishing tool against the polishing boundary PB of the recess.

[0101] In one embodiment, each of polishing heads 22A and 22B may hold a grindstone instead of a grinding tape as a grinding tool. Even with this configuration, the polishing device can remove chipping. Hereinafter, the configuration of a polishing device equipped with a polishing head that holds a grindstone will be described with reference to the drawings.

[0102] 11 is a diagram showing another embodiment of the polishing apparatus. In the embodiment shown in FIG. 11, the polishing apparatus is configured to polish a single wafer W, but may also be configured to polish multiple wafers W.

[0103] As shown in Figure 11, the polishing head 22A is configured to hold a grinding wheel G1 as a polishing tool having a first angle that is an acute angle. The polishing head 22B is configured to hold a grinding wheel G2 as a polishing tool having a second angle that is a right angle or obtuse angle. Hereinafter, the grinding wheels G1 and G2 may be simply referred to as grinding wheels G without any particular distinction being made between them.

[0104] Each of the polishing heads 22A and 22B holds a grindstone G and includes a drive actuator RA that rotates the grindstone G. The drive actuator RA is, for example, a motor, and is held by the movement actuator 23.

[0105] The drive actuator RA has a rotation axis RA-1 to which the grinding wheel G is fixed. When the drive actuator RA is driven, the grinding wheel G rotates around the rotation axis RA-1. By driving the movement actuator 23, the drive actuator RA and the grinding wheel G descend in the depth direction of the wafer W at the peripheral edge of the wafer W. By driving the drive actuator RA, the grinding wheel G comes into contact with the peripheral edge of the wafer W while rotating, and polishes (cuts, grinds) the peripheral edge of the wafer W.

[0106] Fig. 12(a) shows a grinding wheel having a tapered recess, and Fig. 12(b) shows a grinding wheel having a tapered protrusion. As shown in Fig. 12(a), the grinding wheel G1 has a main body G1a fixed to a rotation shaft RA-1 and a tapered recess G1b connected to the main body G1a. The main body G1a and the tapered recess G1b are integrally molded members.

[0107] The tapered recess G1b has a tapered shape that extends toward the central axis CR of the rotation shaft RA-1 and close to the main body G1a, and has a first angle θa as an acute angle. In Fig. 12(a), the tapered recess G1b has a cone shape with a flat portion, but the tapered recess G1b may have a cone shape without a flat portion as long as the first angle θa can be formed.

[0108] 12(b), the grinding wheel G2 has a main body G2a fixed to the rotation shaft RA-1 and a tapered protrusion G2b connected to the main body G2a. The main body G2a and the tapered protrusion G2b are integrally molded members.

[0109] The tapered protrusion G2b has a tapered shape that extends toward the central axis CR of the rotation shaft RA-1 and away from the main body portion G2a, and has a second angle θb as an obtuse angle. The second angle θb may be a right angle. In FIG. 12(b), the tapered protrusion G2b has a truncated cone shape, but the tapered protrusion G2b may have a conical shape as long as the second angle θb can be formed.

[0110] 13(a) to 13(c) are diagrams showing the process of polishing the peripheral portion of the wafer. As shown in Fig. 13(a), the operation control unit 10 (see Fig. 11) drives the movement actuator 23 to lower the grindstone G1 (and the drive actuator RA) and press the grindstone G1 against the peripheral portion of the wafer W. At this time, the grindstone G1 is rotated by the drive actuator RA of the polishing head 22A.

[0111] The polishing head 22A continues polishing the peripheral edge of the wafer W with the grindstone G1, and forms a depression 160 having a predetermined depth in the peripheral edge of the wafer W (see FIG. 13(b)). Thereafter, the operation control unit 10 drives the movement actuator 23 to move the grindstone G1 away from the peripheral edge of the wafer W.

[0112] Furthermore, the operation control unit 10 drives the movement actuator 23 to press the grinding wheel G2 against the polishing boundary portion PB of the recess 160 (see FIG. 13(c)). At this time, the grinding wheel G2 is rotated by the drive actuator RA of the polishing head 22B. The polishing head 22B can remove the chippings CH by pressing the grinding wheel G2 against the chippings CH formed in the polishing boundary portion PB.

[0113] 14(a) and 14(b) are diagrams showing the manufacturing process of a composite wafer. As shown in FIG. 14(a), a first wafer W1 has a depression 160 where chipping CH has been removed. Such a first wafer W1 is bonded to a second wafer W2 to manufacture a composite wafer W.

[0114] When the first wafer W1 is bonded to the second wafer W2, the device layer 200 formed on the first wafer W1 faces the second wafer W2. Thereafter, the back surface of the first wafer W1 (i.e., the surface on which the device layer 200 is not formed) is polished by a predetermined amount (see FIG. 14(b)).

[0115] As shown in the above-described embodiment, the polishing apparatus includes a first polishing head 22A that holds a first polishing tool (a polishing tape or a grindstone) having a first angle as an acute angle, and a second polishing head 22B that holds a second polishing tool (a polishing tape or a grindstone) having a second angle as a right angle or an obtuse angle. Therefore, the polishing apparatus can form a recess 160 on the peripheral edge of a wafer W (a single wafer W or a composite wafer W) and further remove chipping CH formed at a polishing boundary PB of the recess 160.

[0116] The above-described embodiments may be combined as appropriate. For example, the polishing apparatus may include a polishing head that holds a polishing tape and a polishing head that holds a grindstone. Even with such a configuration, the polishing apparatus can remove chippings CH.

[0117] For example, the polishing apparatus may include a polishing head 22A according to the embodiment shown in Fig. 11 and a polishing head 22B according to the embodiment shown in Figs. 2 to 9 (or Fig. 10B). In this case, the polishing head 22A holds a grindstone G1 as the polishing tool. The polishing head 22B holds a polishing tape T2 (or a combination of the polishing tape T2 and a pressing member 210B) as the polishing tool.

[0118] The grindstone G1 can polish the wafer W faster than the polishing tape T1, thereby shortening the polishing time. In this case, when the wafer W is polished by the grindstone G1 held by the polishing head 22A, the surface of the depression 160 becomes rough after polishing is completed.

[0119] Therefore, by finish-polishing the depression 160 of the wafer W using the polishing tape T2 (or a combination of the polishing tape T2 and the pressing member 210B) held by the polishing head 22B, it is possible to increase the flatness of the surface of the depression 160. In other words, with this configuration, the polishing apparatus can shorten the polishing time and improve the flatness of the surface of the depression 160.

[0120] 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. [Explanation of symbols]

[0121] 3 Substrate holding device 10 Operation control section 10a storage device 10b Processing equipment 12 Holding stage 12a Board holding surface 12b opening 15 Stage rotation device 16 Vacuum Line 17 Stage axis 18 Liquid supply nozzle 21 Pressing member 21A Pressing surface 21B Slope 22A 1st Polishing Head 22B No. 2 Polishing Head 23 Moving Actuator 26 Payout reel 27 Take-up reel 30 Tape feed mechanism 32 Sensor Targets 33 Displacement Sensor 36 Last guide roller 37 Leading guide roller 200 Device Layer 210A, 210B Pressing member 210A-1 Pressing surface 210A-2 Inclined surface 210B-1 Pressing surface 210B-2 Inclined surface 300 Last guide roller actuator 301 Leading guide roller actuator W composite substrate W1 First board W2 Second board CH Chipping PB polishing boundary CL axis center T1 Coarse Polishing Tape T2 Finish Polishing Tape θ1 1st angle θ2 2nd angle θ3 3rd angle θα 1st angle θβ 2nd angle θa 1st angle θb 2nd angle AR1 Area opposite to the pressing surface AR2 Area facing the inclined surface G1 grinding stone G1a main body G1b tapered recess G2 grinding stone G2a main body G2b tapered convex part RA drive actuator RA-1 Rotating Axis

Claims

1. A polishing apparatus comprising: a first abrasive head holding a first abrasive tool having a first angle as an acute angle; a second abrasive head holding a second abrasive tool having a second angle as a right angle or an obtuse angle; the first polishing head presses the first polishing tool against a peripheral edge portion of the substrate to form a depression in the peripheral edge portion; The second polishing head presses the second polishing tool against the polishing boundary of the recess.

2. the first polishing head corresponds to a rough polishing head that presses a rough polishing tape as the first polishing tool against the peripheral edge portion to form a recess in the peripheral edge portion, the second polishing head corresponds to a finish polishing head that presses a finish polishing tape serving as the second polishing tool against the polishing boundary portion, the rough polishing head supports the rough polishing tape so that the tape angle of the rough polishing tape is the first angle; 2. The polishing apparatus according to claim 1, wherein the finish polishing head supports the finish polishing tape so that the tape angle of the finish polishing tape is the second angle.

3. Each of the rough polishing head and the finish polishing head comprises: a pressing member for pressing the rough polishing tape and the finish polishing tape against the peripheral edge portion; a front guide roller disposed upstream of the pressing member in the conveying direction of the rough polishing tape and the finish polishing tape, and disposed adjacent to the pressing member; 3. The polishing apparatus according to claim 2, further comprising: a front guide roller actuator that moves the front guide roller.

4. 4. The polishing apparatus according to claim 3, wherein the immediately preceding guide roller actuator is configured to move the immediately preceding guide roller in a direction approaching the pressing member and a direction away from the pressing member.

5. the polishing apparatus includes an operation control unit that controls an operation of the immediately preceding guide roller actuator, The operation control unit the immediately preceding guide roller actuator is operated to move the immediately preceding guide roller until the tape angle of the rough polishing tape becomes the first angle; 4. The polishing apparatus according to claim 3, wherein the immediately preceding guide roller actuator is operated to move the immediately preceding guide roller until the tape angle of the finish polishing tape reaches the second angle.

6. The operation control unit operating the immediately preceding guide roller actuator to move the rough polishing tape in a depth direction of the substrate while the tape angle is set to the first angle, thereby forming a recess having a predetermined depth in the peripheral edge portion; 6. The polishing apparatus according to claim 5, wherein the front guide roller actuator is operated to set the tape angle at the second angle and press the finish polishing tape against the polishing boundary portion.

7. 7. The polishing apparatus according to claim 6, wherein the operation control section operates the immediately preceding guide roller actuator to press the finish polishing tape in a region located between the immediately preceding guide roller and the pressing member against the polishing boundary section.

8. Each of the rough polishing head and the finish polishing head comprises: a preceding guide roller disposed upstream of the immediately preceding guide roller in the conveying direction of the rough polishing tape and the finish polishing tape, and disposed adjacent to the immediately preceding guide roller; a leading guide roller actuator that moves the leading guide roller, 4. The polishing apparatus according to claim 3, wherein the leading guide roller actuator moves the leading guide roller until the leading guide roller reaches a third angle that is larger than the second angle.

9. the polishing apparatus includes an operation control unit that controls an operation of the leading guide roller actuator, 9. The polishing apparatus according to claim 8, wherein the operation control unit operates the immediately preceding guide roller actuator to press the finish polishing tape against the polishing boundary portion, and then operates the leading guide roller actuator to move the leading guide roller until the tape angle becomes the third angle.

10. the first grinding head holds a first grindstone as the first grinding tool, the second grinding head holds a second grindstone as the second grinding tool, the first grindstone has a tapered recess that forms the first angle; 2. The polishing apparatus according to claim 1, wherein the second grindstone has a tapered protrusion that forms the second angle.

11. A polishing method comprising: a first polishing tool having a first acute angle is pressed against a peripheral edge of the substrate by a first polishing head to form a recess in the peripheral edge; A polishing method in which a second polishing tool having a second angle, which may be a right angle or an obtuse angle, is pressed against the polishing boundary of the recess by a second polishing head.

12. the first polishing head corresponds to a rough polishing head that presses a rough polishing tape as the first polishing tool against the peripheral edge portion to form a recess in the peripheral edge portion, the second polishing head corresponds to a finish polishing head that presses a finish polishing tape serving as the second polishing tool against the polishing boundary portion, a tape angle of the rough polishing tape set to the first angle, and the rough polishing tape is pressed against the peripheral edge portion to form a depression in the peripheral edge portion; The polishing method according to claim 11 , wherein the tape angle of the finish polishing tape is set to the second angle and the finish polishing tape is pressed against the polishing boundary portion.

13. a guide roller disposed upstream of a pressing member in a conveying direction of each of the rough polishing tape and the finish polishing tape and disposed adjacent to the pressing member is operated to set the tape angle to the first angle; The polishing method according to claim 12 , further comprising the step of operating the immediately preceding guide roller to set the tape angle to the second angle.

14. 14. The polishing method according to claim 13, wherein a preceding guide roller arranged upstream of and adjacent to the immediately preceding guide roller in the respective conveying directions of the rough polishing tape and the finish polishing tape is operated to set the tape angle to a third angle greater than the second angle.

15. the first grinding head holds a first grindstone as the first grinding tool, the second grinding head holds a second grindstone as the second grinding tool, pressing the first grindstone, which has a tapered recess that forms the first angle, against the peripheral edge portion to form a depression in the peripheral edge portion; The polishing method according to claim 11 , wherein the second grindstone having a tapered protrusion that forms the second angle is pressed against the polishing boundary.

16. A polishing head, The polishing head includes: a pressing member for pressing the polishing tape against the peripheral edge portion; a front guide roller disposed upstream of the pressing member in the conveying direction of the polishing tape and adjacent to the pressing member; a front guide roller actuator that moves the front guide roller, The immediately preceding guide roller actuator is The immediately preceding guide roller is moved until the tape angle of the polishing tape becomes a first angle as an acute angle. The polishing head moves the immediately preceding guide roller until the tape angle is a second angle that is a right angle or an obtuse angle.

17. 17. The polishing head according to claim 16, wherein the immediately preceding guide roller actuator is configured to move the immediately preceding guide roller in a direction approaching the pressing member and in a direction away from the pressing member.

18. The polishing head includes: With the tape angle set to the first angle by the immediately preceding guide roller actuator, the polishing tape is moved in a depth direction of the substrate to form a recess having a predetermined depth in the peripheral edge portion; 17. The polishing head according to claim 16, wherein the tape angle is set to a second angle by the immediately preceding guide roller actuator, and the polishing tape is pressed against the polishing boundary of the recess.

19. The polishing head includes: a preceding guide roller disposed upstream of the immediately preceding guide roller in the conveyance direction of the polishing tape and adjacent to the immediately preceding guide roller; a leading guide roller actuator that moves the leading guide roller, 17. The polishing head of claim 16, wherein the leading guide roller actuator moves the leading guide roller until the tape angle is at a third angle greater than the second angle.

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