Laser processing apparatus, wafer processing apparatus, and wafer processing method

Abstract

To provide a laser beam machining apparatus, a wafer machining apparatus, and a wafer machining method capable of appropriately adjusting a condensing point of a laser beam to an outer peripheral part of a wafer.SOLUTION: The laser processing apparatus 10 performs laser processing on the wafer 100 having the chamfered portion 111 in the outer peripheral portion 110. The laser processing apparatus 10 includes a holding table 20 that holds the wafer 100, and a laser beam irradiation unit 11 that positions a condensing point of a laser beam with respect to the outer circumferential part 110 of the wafer 100 and applies the laser beam along the outer circumferential part 110. The holding table 20 includes a first table 21 that has a holding surface 21a smaller than the wafer 100 and holds a central portion of the wafer 100, and a second table 22 that locally holds an outer peripheral portion 110 of the wafer 100 to be irradiated with the laser beam.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a laser processing apparatus, a wafer processing apparatus, and a wafer processing method for processing a wafer having a chamfered portion on its outer periphery. [Background technology]

[0002] When the backside of a wafer having a chamfer on the periphery is ground to thin it, the chamfer may be formed into a sharp shape, also known as a knife edge, which can cause cracks and other damage to the wafer.

[0003] To prevent the formation of a knife edge, for example, Patent Document 1 describes a laser processing device that positions the focal point of a laser beam with a wavelength that is transparent to a wafer held on a holding table on the outer periphery of the wafer and irradiates the laser beam before grinding the backside of the wafer, thereby forming a modified region along the outer periphery inside the wafer.When the wafer with the modified region formed along the outer periphery is ground, the chamfered portion is removed from the wafer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-88187 Summary of the Invention [Problem to be solved by the invention]

[0005] Some laser processing machines require the use of a holding table that is smaller than the wafer. In this case, if the center of the wafer is held by the holding table, the height of the wafer's outer periphery changes due to the wafer's bending. If the holding table is tilted, the height of the wafer's outer periphery also changes due to that tilt. This change in the height of the wafer's outer periphery causes the laser beam to shift from the wafer, which is a problem.

[0006] The present invention provides a laser processing device, a wafer processing device, and a wafer processing method that can appropriately align the focal point of a laser beam with the outer periphery of a wafer when the wafer is held on a holding table having a holding surface smaller than the wafer. [Means for solving the problem]

[0007] The present invention provides A laser processing apparatus for performing laser processing on a wafer having a chamfered portion on its outer periphery, a holding table for holding the wafer; a laser beam irradiation unit that positions a focal point of a laser beam with respect to the outer periphery of the wafer held by the holding table and irradiates the laser beam along the outer periphery, The holding table is a first table having a holding surface smaller than the wafer and configured to hold a central portion of the wafer; and a second table that locally holds the outer periphery of the wafer to be irradiated with the laser beam.

[0008] The present invention also provides The above laser processing device, a grinding device that grinds the wafer that has been laser-processed by the laser processing device, the laser beam irradiation unit of the laser processing apparatus positions a focal point of a laser beam relative to the outer periphery of the wafer held by the holding table, and irradiates the laser beam along the outer periphery to form a modified region inside the wafer; The grinding device grinds the wafer while removing the chamfered portion starting from the modified region.

[0009] The present invention also provides A wafer processing method for processing a wafer having a chamfered portion on an outer periphery, comprising: a holding step of holding a central portion of the wafer by a first table having a holding surface smaller than the wafer, and locally holding the outer periphery of the wafer by a second table; and a laser beam irradiation step of positioning a focal point of a laser beam relative to a portion of the outer periphery of the wafer held by the second table, and irradiating the laser beam along the outer periphery of the wafer while rotating the wafer together with the first table. [Effects of the Invention]

[0010] According to the present invention, the holding table has a second table that locally holds the outer periphery of the wafer, so that the height position of the outer periphery of the wafer that is irradiated with the laser beam is fixed, and therefore the focal point of the laser beam can be appropriately aligned with the outer periphery of the wafer. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an enlarged cross-sectional view of the vicinity of the outer periphery 110 of the wafer 100. FIG. [Figure 2] 1 is a block diagram showing the configuration of a wafer processing device 1. FIG. [Figure 3] FIG. 1 is a schematic diagram of a laser processing device 10. [Figure 4] FIG. 1 is a schematic perspective view of a laser processing device 10. [Figure 5]1 is a top view showing a state in which a U-shaped robot hand 31 holds a wafer 100 placed on a holding table 20. FIG. [Figure 6] 3 is a diagram showing the detailed structure of a second table 22. FIG. [Figure 7] 10 is a diagram showing the detailed structure of a modified example of the second table 22. FIG. [Figure 8] 2 is a schematic diagram illustrating grinding of the back surface 102 of the wafer 100 by the grinding device 50. FIG. [Figure 9] 1 is a flow diagram of an embodiment of a wafer processing method for processing a wafer 100 using a wafer processing apparatus 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing apparatus, a wafer processing apparatus, and a wafer processing method according to an embodiment of the present invention will be described below with reference to the accompanying drawings. First, a wafer 100, which is the workpiece, will be described.

[0013] 1 is an enlarged cross-sectional view of the vicinity of the outer periphery 110 of a wafer 100. The wafer 100 is a plate-like object having a circular outer shape, and is made of a semiconductor material such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN). The wafer 100 may also be made of an inorganic material, a metal material, or the like. A front surface 101 of the wafer 100 has a plurality of devices 120, such as integrated circuits (ICs) and large-scale integration (LSIs), formed in areas partitioned into a lattice pattern. A back surface 102 of the wafer 100 serves as the grinding surface to be ground in a grinding step, which will be described later.

[0014] The wafer 100 has a chamfered outer periphery 110, forming a chamfered portion 111 having a substantially arc-shaped cross section. In this specification, the outer periphery 110 refers to the region extending from the chamfered portion 111, which is the outer peripheral edge of the wafer 100, to a position a predetermined distance inward in the radial direction of the wafer 100.

[0015] When the wafer 100 having the chamfered portion 111 formed thereon is thinned by, for example, grinding from the back surface 102 to the portion indicated by the two-dot chain line in FIG. 1 , a sharp knife edge is formed on the outer periphery 110 of the wafer 100. When the knife edge is formed, chipping may occur from the outer periphery 110 of the wafer 100 toward the inside in the radial direction, damaging the wafer 100.

[0016] Therefore, before grinding the back surface 102 of the wafer 100, a laser beam is focused and irradiated along the outer periphery 110 of the wafer 100 to form a modified region M (see FIG. 3) inside the wafer 100. By forming the modified region M along the outer periphery 110 of the wafer 100, it is possible to prevent the chamfered portion 111 from being removed starting from the modified region M when the wafer 100 is ground, thereby preventing the formation of a knife edge.

[0017] Next, the wafer processing apparatus 1, the laser processing apparatus 10, and the wafer processing method according to one embodiment of the present invention will be described.

[0018] 2 is a block diagram showing the configuration of a wafer processing apparatus 1 that processes a wafer 100. The wafer processing apparatus 1 includes a laser processing apparatus 10 and a grinding apparatus 50. The wafer processing apparatus 1 may be configured such that the laser processing apparatus 10 and the grinding apparatus 50 are mounted on a common base as an integrated unit, or may be configured such that the laser processing apparatus 10 and the grinding apparatus 50 are mounted on separate bases as separate units.

[0019] Fig. 3 is a schematic diagram of the laser processing apparatus 10. Fig. 4 is a schematic perspective view of the laser processing apparatus 10. The laser processing apparatus 10 has a laser beam irradiation unit 11 that irradiates a laser beam, and a holding table 20 that holds a wafer 100.

[0020] The laser beam irradiation unit 11 has a laser oscillator 12 that oscillates a YAG laser or a YVO4 laser, an output adjustment unit 13 that adjusts the output of the laser beam to a predetermined power, a mirror 14 that reflects the laser beam output from the output adjustment unit 13, and a condenser lens 15 that condenses the laser beam reflected by the mirror 14 inside the wafer 100. Although not particularly shown, the laser oscillator 12 has a Brewster window, and the laser beam emitted from the laser oscillator 12 is a linearly polarized laser beam.

[0021] The laser beam irradiation unit 11 irradiates a laser beam having a wavelength that is transparent to the wafer 100 from the back surface 102 onto the outer periphery 110 of the wafer 100 held by the holding table 20. Specifically, the laser beam irradiation unit 11 irradiates the laser beam at a position that is a predetermined distance radially inward from the outer periphery (chamfered portion 111) of the wafer 100. At this time, the laser beam irradiation unit 11 forms a modified region M inside the wafer 100 by positioning the focal point of the laser beam at a position deeper than the back surface 102 of the wafer 100.

[0022] The holding table 20 has a first table 21 whose holding surface 21a is smaller than the wafer 100 and holds the center of the wafer 100. The holding surface 21a of the first table 21 is formed in a flat circular shape. The holding surface 21a is made of resin or a porous material, and holds the wafer 100 by suction using a suction force generated by a suction source (not shown) that is connected to the holding surface 21a.

[0023] First table 21 is provided so as to be rotatable about central axis CL extending in the vertical direction. Wafer 100 is held on holding surface 21a of first table 21 so that its center substantially coincides with central axis CL of first table 21, and is provided so as to be rotatable about its central portion as first table 21 rotates. As wafer 100 is rotated, laser beam irradiation unit 11 repeatedly irradiates wafer 100 with a focused laser beam, thereby forming modified region M in an annular shape along outer periphery 110 of wafer 100.

[0024] As described above, the first table 21 has a holding surface 21a that is smaller than the wafer 100, and holds the central portion of the wafer 100. By employing such a small-diameter first table 21, as shown in FIG. 5, a U-shaped robot hand 31 can be used when transferring the wafer 100 to the first table 21 and / or when transferring the wafer 100 from the first table 21. This U-shaped robot hand 31 holds the wafer 100 from below and transfers the wafer 100 from the first table 21 to the grinding device 50. The first table 21 is smaller than the opening 32, which is the open part of the U-shape of the robot hand 31. Therefore, the first table 21 does not interfere with the robot hand 31. Note that the robot hand 31 is not limited to a U-shape and may be a Y-shape.

[0025] However, when wafer 100 is held only at its center by first table 21, wafer 100 bends downward, and the height position (in other words, the vertical position) of outer periphery 110 changes downward relative to the center. Also, when holding surface 21a of first table 21 is inclined, the height position of outer periphery 110 changes relative to the center. In such a state, there is a risk that the focal point of the laser beam may shift from wafer 100.

[0026] 3 and 4, the holding table 20 further includes a second table 22 that locally holds the outer peripheral portion 110 of the wafer 100 to be irradiated with the laser beam. The second table 22 is disposed directly below the condenser lens 15 of the laser beam irradiation unit 11. The laser beam irradiation unit 11 condenses and irradiates the laser beam onto the portion of the outer peripheral portion 110 of the wafer 100 that is locally held by the second table 22, thereby forming a modified region M.

[0027] In this way, since the second table 22 is provided, the height position of the portion of the outer periphery 110 of the wafer 100 that faces the condenser lens 15 of the laser beam irradiation unit 11 is fixed. Therefore, the focal point of the laser beam can be appropriately aligned with the wafer 100. Furthermore, even if the laser processing apparatus 10 vibrates, the vibration of the wafer 100 can be reduced by the second table 22.

[0028] Furthermore, the second table 22 is placed directly below the condenser lens 15 of the laser beam irradiation unit 11 and locally holds the outer periphery 110 of the wafer 100, so that interference with the robot hand 31 described above can also be suppressed.

[0029] In this embodiment, the laser beam irradiation unit 11 and the second table 22 do not move during laser beam irradiation, but move relative to the outer periphery 110 of the wafer 100 as the wafer 100 rotates in accordance with the rotation of the first table 21. This allows stable laser processing to be performed.

[0030] Figure 6 shows the detailed structure of second table 22, with the upper figure being a cross-sectional side view and the lower figure being a top view. The thick black arrows in Figure 6 indicate the flow of pressurized air. In this embodiment, second table 22 is configured as a Bernoulli chuck that suction-holds wafer 100 without contact using negative pressure generated by the ejection of pressurized air.

[0031] The second table 22 includes a flow path 221 through which pressurized air supplied from a supply source not shown flows, an expansion section 222 that is connected to the flow path 221 and opens upward while expanding in diameter, a guide section 223 that is provided at the connection between the flow path 221 and the expansion section 222 and that guides the pressurized air introduced into the expansion section 222 radially along the surface of the expansion section 222, and an ejection section 224 that ejects the pressurized air from between the surface of the expansion section 222 and the guide section 223.

[0032] By jetting pressurized air radially along the surface of enlarged diameter portion 222, a negative pressure is generated in the center of enlarged diameter portion 222 according to Bernoulli's principle, and this negative pressure acts on wafer 100 as indicated by the white arrows in the figure, thereby suction-holding wafer 100. In addition, since pressurized air flows between the outer part of enlarged diameter portion 222 and wafer 100, wafer 100 is suction-held on second table 22 without coming into contact with it.

[0033] In this way, second table 22 is a Bernoulli chuck and holds outer periphery 110 of wafer 100 in a non-contact manner, so that wafer 100 can move smoothly relative to second table 22.

[0034] Figure 7 shows the detailed structure of a modified example of second table 22, with the upper figure being a cross-sectional side view and the lower figure being a top view. The thick black arrows in Figure 7 indicate the flow of pressurized air. For ease of explanation, one horizontal direction in Figure 7 is defined as the X direction, and the other direction perpendicular to the X direction is defined as the Y direction.

[0035] In the modified example, second table 22 also includes a Bernoulli chuck that sucks and holds wafer 100 in a non-contact manner using negative pressure generated by jetting pressurized air. Second table 22 in the modified example includes a flow path 221 through which pressurized air supplied from a supply source (not shown) flows, a recess 225 that extends in the Y direction and is gradually inclined in the X direction toward an X-direction central portion 225c, and a plurality of jetting portions 226 that are provided along the Y direction near X-direction central portion 225c of recess 225 and that jet the pressurized air introduced into recess 225 along the surface of recess 225. Jetting portions 226 are provided alternately along the Y direction, with one jetting portion on the −X side of X-direction central portion 225c that jets the pressurized air to the +X side and another jetting portion on the +X side of X-direction central portion 225c that jets the pressurized air to the −X side.

[0036] Even with this configuration, a negative pressure is generated in recess 225 according to Bernoulli's principle, and this negative pressure causes a suction force to act on wafer 100 as indicated by the white arrow in the figure, thereby suction-holding wafer 100. Furthermore, pressurized air flows between the outer portion of recess 225 and wafer 100, so wafer 100 is suction-held on second table 22 without coming into contact with it.

[0037] 8 is a schematic diagram illustrating grinding of the back surface 102 of the wafer 100 by the grinding apparatus 50, with the upper diagram showing the state before grinding and the lower diagram showing the state after grinding. A plate-shaped support member 150 is attached to the front surface 101 of the wafer 100 before grinding. Specifically, the support member 150 is attached before laser processing by the laser processing apparatus 10, for example. Note that the support member 150 is not shown in FIGS. 3 to 7.

[0038] The grinding apparatus 50 includes, for example, a holding table 51 that holds the front surface 101 of the wafer 100 via a support member 150, and a grinding unit 52 that is disposed opposite the holding table 51 and is configured to be vertically movable and rotatable. The grinding apparatus 50 grinds the back surface 102 of the wafer 100 held by the holding table 51 with a grinding wheel 53 of the grinding unit 52, thereby thinning the wafer 100. As the wafer 100 is ground, stress is generated in the modified region M, and a chamfered portion 111 of the wafer 100 is removed starting from the modified region M.

[0039] 9 is a flow diagram of one embodiment of a wafer processing method for processing the wafer 100 using the above-described wafer processing apparatus 1. The wafer processing method includes a holding step S1, a laser beam irradiation step S2, and a grinding step S3.

[0040] In the holding step S1, the first table 21 holds the center portion of the wafer 100, and the second table 22 locally holds the outer periphery 110 of the wafer 100. In the laser beam irradiation step S2, the focal point of the laser beam is positioned on the front surface 101 of the wafer 100 or at a predetermined depth from the back surface 102 for the portion of the outer periphery 110 of the wafer 100 held by the second table 22. In the laser beam irradiation step S2, the laser beam is irradiated along the outer periphery 110 of the wafer 100 while rotating the first table 21, thereby forming an annular modified region M inside the wafer 100. In the grinding step S3, the wafer 100 with the modified region M formed therein is ground by the grinding device 50.

[0041] By using this wafer processing method, the height position of the portion of the outer periphery 110 of the wafer 100 that faces the focusing lens 15 of the laser beam irradiation unit 11 is fixed, and the focusing point of the laser beam can be appropriately aligned with the wafer 100 in the laser beam irradiation step S2.

[0042] Furthermore, in the holding step S1, second table 22 holds outer periphery 110 of wafer 100 locally without contact, so that wafer 100 can move smoothly relative to second table 22.

[0043] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiment may be combined in any manner without departing from the spirit of the invention.

[0044] For example, the laser processing by the laser processing apparatus 10 in the embodiment described above was intended to form a modified region M inside the outer periphery 110 of the wafer 100, but is not limited thereto and may be intended to remove a volume of the outer periphery 110 of the wafer 100 by laser ablation. Specifically, the laser beam irradiation unit 11 of the laser processing apparatus 10 may be configured to position the focal point of the laser beam on the back surface 102 of the outer periphery 110 of the wafer 100 and irradiate the laser beam along the outer periphery 110. The chamfered portion 111 of the wafer 100 can also be removed by such laser ablation.

[0045] Even in the laser processing apparatus 10 configured as described above, the height position of the portion of the outer circumferential portion 110 of the wafer 100 facing the condenser lens 15 of the laser beam irradiation unit 11 is fixed by providing the second table 22. Therefore, the focal point of the laser beam can be appropriately aligned with the back surface 102 of the wafer 100.

[0046] This specification describes at least the following: In parentheses, components corresponding to those in the above-described embodiments are shown as examples, but the present invention is not limited to these.

[0047] (1) A laser processing apparatus (laser processing apparatus 10) for performing laser processing on a wafer (wafer 100) having a chamfered portion (chamfered portion 111) on an outer periphery (outer periphery 110), a holding table (holding table 20) for holding the wafer; a laser beam irradiation unit that positions a focal point of a laser beam with respect to the outer periphery of the wafer held by the holding table and irradiates the laser beam along the outer periphery, The holding table is a first table having a holding surface smaller than the wafer and configured to hold a central portion of the wafer; a second table that locally holds the outer periphery of the wafer to be irradiated with the laser beam; Laser processing equipment.

[0048] When the center of a wafer is held by a first table having a holding surface smaller than the wafer, the height of the wafer's outer periphery changes depending on the wafer's bending and the tilt of the first table. According to (1), a second table is provided to locally hold the wafer's outer periphery, so the height position of the wafer's outer periphery, where the laser beam is irradiated, is fixed. This allows the focal point of the laser beam to be properly aligned with the wafer.

[0049] (2) The laser processing device according to (1), the second table locally holds the outer periphery of the wafer in a non-contact manner by a negative pressure generated by ejecting gas; Laser processing equipment.

[0050] According to (2), the second table holds the outer periphery of the wafer without contacting it, so that the relative movement between the second table and the wafer can be carried out smoothly.

[0051] (3) The laser processing apparatus according to (1) or (2), the first table holds the wafer rotatably around the center portion; Laser processing equipment.

[0052] According to (3), since the wafer can be rotated around the center, there is no need to move the laser beam irradiation unit and the second table during laser processing, and stable laser processing can be performed.

[0053] (4) A laser processing apparatus according to any one of (1) to (3), the wafer is held from below by a U-shaped or Y-shaped robot hand (robot hand 31) when being transferred to and / or from the first table; The first table is smaller than the opening (opening 32) which is the U-shaped or Y-shaped opening of the robot hand. Laser processing equipment.

[0054] According to (4), the holding surface of the first table is smaller than the opening of the U-shaped or Y-shaped robot hand, so interference between the robot hand and the first table can be suppressed. In addition, the second table is configured to locally hold the outer periphery of the wafer, so interference between the robot hand and the second table can also be suppressed.

[0055] (5) A laser processing apparatus (laser processing apparatus 10) according to any one of (1) to (4), a grinding device (grinding device 50) that grinds the wafer that has been laser-processed by the laser processing device, the laser beam irradiation unit of the laser processing device positions a focal point of a laser beam relative to the outer periphery of the wafer held by the holding table, and irradiates the laser beam along the outer periphery to form a modified region (modified region M) inside the wafer; the grinding device grinds the wafer while removing the chamfered portion starting from the modified region. Wafer processing equipment.

[0056] According to (5), the chamfered portion of the wafer can be removed during grinding, so that the formation of a knife edge on the wafer during grinding and the damage to the wafer can be suppressed.

[0057] (6) A wafer processing method for processing a wafer (wafer 100) having a chamfered portion (chamfered portion 111) on an outer periphery (outer periphery 110), comprising: a holding step (holding step S1) in which a first table (first table 21) having a holding surface (holding surface 21a) smaller than the wafer holds the central portion of the wafer, and a second table (second table 22) locally holds the outer periphery of the wafer; a laser beam irradiation step (laser beam irradiation step S2) of positioning a focal point of a laser beam on a portion of the outer periphery of the wafer held by the second table, and irradiating the laser beam along the outer periphery of the wafer while rotating the wafer together with the first table, Wafer processing methods.

[0058] According to (6), a second table is provided to locally hold the outer periphery of the wafer, so that the height position of the outer periphery of the wafer where the laser beam is irradiated is fixed, and therefore the focal point of the laser beam can be appropriately aligned with the wafer.

[0059] (7) The wafer processing method according to (6), In the holding step, the second table holds the outer periphery of the wafer locally in a non-contact manner. Wafer processing methods.

[0060] According to (7), the second table holds the outer periphery of the wafer without contacting it, so that the relative movement between the second table and the wafer can be performed smoothly. [Explanation of symbols]

[0061] 1. Wafer processing equipment 10 Laser processing equipment 20 Holding table 21 Table 1 21a Holding surface 22 Table 2 31 Robot Hand 32 Opening 50 Grinding equipment 100 wafers 110 Outer periphery M Modification area S1 Hold step S2 Laser beam irradiation step

Claims

1. A laser processing apparatus for performing laser processing on a wafer having a chamfered portion on its outer periphery, a holding table for holding the wafer; a laser beam irradiation unit that positions a focal point of a laser beam with respect to the outer periphery of the wafer held by the holding table and irradiates the laser beam along the outer periphery, The holding table is a first table having a holding surface smaller than the wafer and configured to hold a central portion of the wafer; a second table that locally holds the outer periphery of the wafer to be irradiated with the laser beam; Laser processing equipment.

2. The laser processing apparatus according to claim 1, the second table locally holds the outer periphery of the wafer in a non-contact manner by a negative pressure generated by ejecting gas; Laser processing equipment.

3. 3. The laser processing apparatus according to claim 1, the first table holds the wafer rotatably around the center portion; Laser processing equipment.

4. 3. The laser processing apparatus according to claim 1, the wafer is held from below by a U-shaped or Y-shaped robot hand when being transferred to and / or from the first table; the first table is smaller than an opening that is the U-shaped or Y-shaped opening of the robot hand; Laser processing equipment.

5. The laser processing device according to claim 1 or 2; a grinding device that grinds the wafer that has been laser-processed by the laser processing device, the laser beam irradiation unit of the laser processing apparatus positions a focal point of a laser beam relative to the outer periphery of the wafer held by the holding table, and irradiates the laser beam along the outer periphery to form a modified region inside the wafer; the grinding device grinds the wafer while removing the chamfered portion starting from the modified region. Wafer processing equipment.

6. A wafer processing method for processing a wafer having a chamfered portion on an outer periphery, comprising: a holding step of holding a central portion of the wafer by a first table having a holding surface smaller than the wafer, and locally holding the outer periphery of the wafer by a second table; a laser beam irradiation step of positioning a focal point of a laser beam on a portion of the outer periphery of the wafer held by the second table, and irradiating the laser beam along the outer periphery of the wafer while rotating the wafer together with the first table, Wafer processing methods.

7. 7. The wafer processing method according to claim 6, In the holding step, the second table holds the outer periphery of the wafer locally in a non-contact manner. Wafer processing methods.

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