Processing device and processing method

Abstract

Provided are a processing apparatus and a processing method. The processing apparatus includes a holding unit that holds a processing target, a modification unit that forms a plurality of focal points in a surface direction by irradiating laser light into the processing target, a moving mechanism that relatively moves the holding unit and the modification unit in a horizontal direction, a rotating mechanism that relatively rotates the holding unit and the modification unit, and a control unit that controls a forming operation of the focal points in the processing target, and controls the number and arrangement of the focal points formed simultaneously at different positions in the surface direction of the processing target based on a relative rotation speed of the processing target and an irradiation pitch of the laser light when the focal points are formed by relatively rotating the processing target held by the holding unit with respect to the modification unit by the rotating mechanism while periodically irradiating laser light into the processing target from the modification unit and relatively moving the modification unit with respect to the holding unit in a radial direction by the moving mechanism.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on July 9, 2020, with application number 202080050598.9 and title "Processing Apparatus and Processing Method". Technical Field

[0002] This disclosure relates to a processing apparatus and a processing method. Background Technology

[0003] Patent Document 1 discloses a method for processing a stacked wafer. According to Patent Document 1, the method includes a modified surface forming step, which forms a modified surface inside the stacked wafer, and a separation step, which separates a portion of a first wafer from the stacked wafer using the modified surface as a boundary.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-32690 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The technology disclosed herein improves the efficiency of separating and processing objects.

[0009] Solution for solving the problem

[0010] One aspect of this disclosure is a processing apparatus for processing a workpiece, the processing apparatus comprising: a holding section for holding the workpiece; a modification section for irradiating the interior of the workpiece with laser light to form a plurality of focal points along a surface direction; a moving mechanism for moving the holding section and the modification section relative to each other in a horizontal direction; a rotating mechanism for rotating the holding section and the modification section relative to each other; and a control section for controlling the formation of the focal points on the workpiece, wherein, while the workpiece held in the holding section is rotated relative to the modification section by the rotating mechanism, laser light is periodically irradiated from the modification section into the interior of the workpiece, and the modification section is moved relative to the holding section in a radial direction by the moving mechanism to form the focal points, the control section controls the number and arrangement of the focal points formed simultaneously at different positions in the surface direction of the workpiece based on the relative rotational speed of the workpiece and the irradiation interval of the laser light.

[0011] The effects of the invention

[0012] According to this disclosure, the efficiency of separating and processing objects can be improved. Attached Figure Description

[0013] Figure 1 This is a top view schematically illustrating an example of the structure of a wafer processing system.

[0014] Figure 2 This is a side view showing a schematic example of a superimposed wafer structure.

[0015] Figure 3 This is a side view showing a schematic example of a structure representing a portion of an overlapping wafer.

[0016] Figure 4 This is a top view showing a structural example of a modification device.

[0017] Figure 5 This is a side view showing a schematic example of the structure of the modification device.

[0018] Figure 6 This is a flowchart illustrating an example of the main processes in wafer processing.

[0019] Figure 7 This is an illustrative diagram showing an example of the main processes in wafer processing.

[0020] Figure 8 This is an illustration showing the process of forming a periphery modification layer on a wafer.

[0021] Figure 9 This is an illustration showing the process of forming a periphery modification layer on a wafer.

[0022] Figure 10 This is an explanatory diagram illustrating the process of forming an internal surface modification layer on a wafer.

[0023] Figure 11 This is an explanatory diagram illustrating the process of removing the periphery of a wafer.

[0024] Figure 12 This is an illustration of the internal surface modification layer that has been formed.

[0025] Figure 13 This is an explanatory diagram illustrating the process of forming a center modification layer on a wafer.

[0026] Figure 14 This is an explanatory diagram illustrating the process of separating wafers.

[0027] Figure 15 This is an illustrative diagram showing other methods for processing wafer separation.

[0028] Figure 16 This is a flowchart illustrating an example of the process for forming the internal surface modification layer involved in this embodiment.

[0029] Figure 17 This is an explanatory diagram illustrating an example of the formation process of the internal surface modification layer involved in this embodiment.

[0030] Figure 18 This is an explanatory diagram showing the formation of an internal surface modification layer inside the processed wafer.

[0031] Figure 19 This is an explanatory diagram showing other examples of the formation of the internal surface modification layer. Detailed Implementation

[0032] In the manufacturing process of semiconductor devices, for example, as disclosed in Patent Document 1, a modified layer is formed by irradiating the interior of a semiconductor wafer (hereinafter referred to as a wafer) such as a circular substrate on which multiple electronic circuits and other devices are formed on the surface, and the wafer is separated based on the modified layer, thereby thinning the wafer.

[0033] In this wafer separation process, the modified layer is formed inside the wafer, and then a tensile force is applied in the peeling direction while maintaining the surface side and the back side. This causes the wafer to be separated and thinned, with the formed modified layer and any cracks (hereinafter referred to as "cracks") extending from it as boundaries. Furthermore, in the following description, the wafer with the device formed on the surface side of the separated wafer is sometimes referred to as the "first separated wafer," and the back side is referred to as the "second separated wafer."

[0034] Here, in the modified surface forming step described in Patent Document 1, the laser beam irradiated from the laser beam irradiation mechanism is focused at a point inside the first wafer, and a modified surface is formed at that focused point (single-focus processing).

[0035] However, in cases where single-focus processing is performed on the entire surface of the wafer, i.e., where the modified layer is formed one by one on the entire surface of the wafer, the productivity (production cycle time) of the modification equipment that forms the modified layer decreases. That is, since the modified layer is formed one by one, the formation of the modified layer takes time, and the productivity of the modification equipment decreases, so there is room for improvement in terms of the formation of the modified layer.

[0036] The technology disclosed herein improves the efficiency of separating and processing the object to be processed. Hereinafter, a wafer processing system equipped with a processing apparatus and a wafer processing method according to this embodiment will be described with reference to the accompanying drawings. Furthermore, in this specification and the accompanying drawings, elements having substantially the same functional structure are labeled with the same reference numerals, thereby omitting repeated descriptions.

[0037] First, the structure of the wafer processing system will be explained. Figure 1 This is a top view schematically showing the outline of the structure of the wafer processing system 1.

[0038] In wafer processing system 1, for example... Figure 2 As shown, the overlapping wafer T, formed by bonding the processing wafer W and the support wafer S, is processed. Furthermore, in the wafer processing system 1, the processing wafer W is separated for thinning. Hereinafter, the side of the processing wafer W that is bonded to the support wafer S is referred to as surface Wa, and the side opposite to surface Wa is referred to as back surface Wb. Similarly, the side of the support wafer S that is bonded to the processing wafer W is referred to as surface Sa, and the side opposite to surface Sa is referred to as back surface Sb. In this embodiment, the processing wafer W corresponds to the processing object of this disclosure.

[0039] The processed wafer W is, for example, a semiconductor wafer such as a silicon wafer with a circular plate shape. A device layer D, including multiple electronic circuits and other devices, is formed on the surface Wa of the processed wafer W. In addition, an oxide film Fw, such as a SiO2 film (TEOS film), is also formed on the device layer D. Furthermore, in this embodiment, the processed wafer W constitutes the wafer that is the object of separation as described above.

[0040] The support wafer S is used to support the processing wafer W. An oxide film Fs, such as a SiO2 film (TEOS film), is formed on the surface Sa of the support wafer S. Furthermore, if multiple devices are formed on the surface Sa of the support wafer S, a device layer (not shown) is formed on the surface Sa in the same manner as on the processing wafer W.

[0041] In addition, in the following description, to avoid complicating the illustrations, the illustrations of device layer D and oxide films Fw and Fs are sometimes omitted.

[0042] In addition to the thinning process already described, the wafer W undergoes an edge trimming process to prevent the periphery of the wafer W from becoming a sharp shape (so-called a blade shape) due to the thinning process. For example, Figure 3 As shown, a peripheral modification layer M1 is formed by irradiating a laser at the boundary between the peripheral portion We and the central portion Wc, which is to be removed. The peripheral portion We is then peeled off using this peripheral modification layer M1 as a base point to perform edge trimming. Furthermore, the peripheral portion We removed by edge trimming is, for example, a radial range of 1 mm to 5 mm from the outer end of the processed wafer W. The method of edge trimming will be described later.

[0043] Here, when processing the peripheral portion We of wafer W, it may be impossible to properly remove the peripheral portion We when the processing wafer W is bonded to the support wafer S. Therefore, an unbonded region Ae is formed at the interface between the processing wafer W and the support wafer S, corresponding to the portion of the peripheral portion We that is the object to be removed during edge trimming, for proper edge trimming. Specifically, as... Figure 3As shown, a bonding region Ac, where the processing wafer W and the support wafer S are bonded, and an unbonded region Ae, where the bonding strength between the processing wafer W and the support wafer S is reduced, are formed at the interface between them. Furthermore, it is preferable that the outer end of the bonding region Ac is located slightly radially outward from the inner end of the peripheral portion We to be removed.

[0044] The unbonded region Ae can be formed, for example, before bonding. Specifically, the bonding interface of the pre-bonding wafer W can be reduced by removing it through grinding, wet etching, laser irradiation, or hydrophobication by coating with a hydrophobic agent, thereby forming the unbonded region Ae. Furthermore, the "bonding interface" that forms the unbonded region Ae is the portion of the pre-bonding wafer W that forms the interface that is actually bonded to the supporting wafer S.

[0045] The unbonded region Ae can also be formed after bonding, for example. Specifically, by irradiating the interface in a portion corresponding to the periphery We of the bonded processed wafer W with a laser, the bonding strength relative to the surface Sa of the support wafer S is reduced, thereby forming the unbonded region Ae. Furthermore, the unbonded region Ae can be formed at any location near the bonding interface between the processed wafer W and the support wafer S, as long as it can appropriately reduce the bonding force between the processed wafer W and the support wafer S at the periphery of the processed wafer W. That is, in this embodiment, "near the bonding interface" is defined as including the interior of the processed wafer W, the interior of the device layer D, the interior of the oxide film Fw, etc.

[0046] like Figure 1 As shown, the wafer processing system 1 has a structure that integrates the loading / unloading station 2 and the processing station 3. For example, the loading / unloading station 2 performs loading and unloading of a box Ct capable of accommodating multiple overlapping wafers T between itself and the outside. The processing station 3 is equipped with various processing devices for processing the overlapping wafers T.

[0047] A box-loading platform 10 is provided at the loading / unloading station 2. In the illustrated example, multiple boxes, such as three boxes Ct, are freely arranged in a row along the Y-axis on the box-loading platform 10. Furthermore, the number of boxes Ct placed on the box-loading platform 10 is not limited to this embodiment and can be arbitrarily determined.

[0048] On the negative X-axis side of the loading / unloading station 2 and the cassette stage 10, a wafer transport device 20 is disposed adjacent to the cassette stage 10. The wafer transport device 20 is configured to move freely along a transport path 21 extending along the Y-axis. Furthermore, the wafer transport device 20 has, for example, two transport arms 22, 22 for holding and transporting overlapping wafers T. Each transport arm 22 is configured to move freely in the horizontal and vertical directions and about the horizontal and vertical axes. Moreover, the structure of the transport arms 22 is not limited to this embodiment, and any structure can be adopted. Furthermore, the wafer transport device 20 is configured to transport overlapping wafers T to the cassette stage 10 and the transport device 30 described later.

[0049] On the negative X-axis side of the wafer transfer device 20 at the transfer station 2, a transfer device 30 for transferring overlapping wafers T is provided adjacent to the wafer transfer device 20.

[0050] Processing station 3 is provided with, for example, three processing blocks G1 to G3. The first processing block G1, the second processing block G2, and the third processing block G3 are arranged in the order described, from the positive X-axis side (the side of the transfer station 2) to the negative X-axis side.

[0051] The first processing block G1 is provided with an etching device 40, a cleaning device 41, and a wafer transport device 50. The etching device 40 and the cleaning device 41 are arranged in a stacked manner. However, the number and arrangement of the etching device 40 and the cleaning device 41 are not limited thereto. For example, the etching device 40 and the cleaning device 41 may also be arranged in a manner along the X-axis direction. Furthermore, these devices, the etching device 40 and the cleaning device 41, may also be stacked separately.

[0052] The etching apparatus 40 etches the separation surface of the processed wafer W, which has been ground by the processing apparatus 80 (described later). For example, a chemical solution (etching solution) is supplied to the separation surface to perform wet etching. Examples of chemical solutions used include HF, HNO3, H3PO4, TMAH, Choline, and KOH.

[0053] The cleaning apparatus 41 cleans the separation surface of the processed wafer W after it has been ground by the processing apparatus 80 (described later). For example, a brush is brought into contact with the separation surface to scrub it. Alternatively, pressurized cleaning fluid can be used to clean the separation surface. Furthermore, the cleaning apparatus 41 may also have a structure that cleans both the separation surface of the wafer W and the back surface Sb of the supporting wafer S.

[0054] The wafer transport device 50 is, for example, disposed on the negative Y-axis side of the etching device 40 and the cleaning device 41. The wafer transport device 50 has, for example, two transport arms 51, 51 that hold and transport overlapping wafers T. Each transport arm 51 is configured to be movable freely in the horizontal and vertical directions and about the horizontal and vertical axes. Furthermore, the structure of the transport arms 51 is not limited to this embodiment and any structure can be adopted. Moreover, the wafer transport device 50 is configured to transport overlapping wafers T to the transport device 30, the etching device 40, the cleaning device 41, and the modification device 60 described later.

[0055] A modification device 60 and a wafer transport device 70 are provided in the second processing block G2. Furthermore, the number and configuration of the modification devices 60 are not limited to this embodiment, and multiple modification devices 60 can be stacked.

[0056] The modification device 60 irradiates the interior of the processed wafer W with a laser to form an unbonded region Ae, a peripheral modification layer M1, an internal surface modification layer M2, and a central modification layer M3. The detailed structure of the modification device 60 is described later.

[0057] The wafer transport device 70 is, for example, disposed on the positive Y-axis side of the modification device 60. The wafer transport device 70 has, for example, two transport arms 71, 71 that hold and transport the overlapping wafer T. Each transport arm 71 is supported by a multi-jointed arm member 72 and is configured to be freely movable in the horizontal and vertical directions and about the horizontal and vertical axes. Furthermore, the structure of the transport arms 71 is not limited to this embodiment and any structure can be adopted. Moreover, the wafer transport device 70 is configured to transport the overlapping wafer T to the cleaning device 41, the modification device 60, and the processing device 80 described later.

[0058] A processing device 80 is provided in the third processing block G3. Furthermore, the number and configuration of the processing devices 80 are not limited to this embodiment, and multiple processing devices 80 can be arbitrarily configured.

[0059] The processing apparatus 80 includes a rotary table 81. The rotary table 81 is configured to rotate freely about a vertical rotation centerline 82 via a rotation mechanism (not shown). Two chucks 83 are provided on the rotary table 81 to hold and hold the overlapping wafer T. The chucks 83 are evenly arranged on the same circumference as the rotary table 81. By rotating the rotary table 81, the two chucks 83 can be moved to a junction position 80a and a processing position 80b. Furthermore, each of the two chucks 83 is configured to rotate about a vertical axis via the rotation mechanism (not shown).

[0060] The overlapping wafer T is joined at the junction position 80a. A grinding unit 84 is positioned at the processing position 80b to grind the processing wafer W. The grinding unit 84 has a grinding section 85, which includes a ring-shaped, rotatable grinding stone (not shown). Furthermore, the grinding section 85 is configured to move vertically along the support column 86. Moreover, the processing wafer W, held by the chuck 83, is brought into contact with the grinding stone, and both the chuck 83 and the grinding stone are rotated.

[0061] The wafer processing system 1 described above is equipped with a control device 90 as a control unit. The control device 90 is, for example, a computer equipped with a CPU, memory, etc., and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of wafer W in the wafer processing system 1. Additionally, the program storage unit also stores a program for controlling the operation of the drive systems of the various processing devices, transport devices, etc., described above to implement the wafer processing described later in the wafer processing system 1. Furthermore, the above-mentioned program may be a program recorded in a computer-readable storage medium H and installed from that storage medium H into the control device 90.

[0062] In addition, control devices (not shown) for independently controlling the respective processing devices can be provided in each of the above-mentioned processing devices.

[0063] Next, the modification device 60 described above will be explained. Figure 4 , Figure 5 These are top and side views, respectively, showing the outline of the structure of the modification device 60.

[0064] The modification apparatus 60 has a suction cup 100 as a holding part, which holds the overlapping wafer T via its upper surface. With the processing wafer W positioned on the upper side and the supporting wafer S positioned on the lower side, the suction cup 100 adsorbs and holds the back surface Sb of the supporting wafer S. The suction cup 100 is supported on a sliding stage 102 via an air bearing 101. A rotation mechanism 103 is provided on the lower surface of the sliding stage 102. The rotation mechanism 103, for example, incorporates a motor as a drive source. The suction cup 100 is configured to rotate freely about a vertical axis via the air bearing 101 through the rotation mechanism 103. The sliding stage 102 is configured to move along a guide rail 105 provided on the base 106 and extending in the Y-axis direction via a moving mechanism 104, which serves as a holding part moving mechanism, provided on its lower surface. Furthermore, there are no particular limitations on the drive source of the moving mechanism 104; for example, a linear motor can be used.

[0065] A laser head 110, serving as a modification section, is disposed above the chuck 100. The laser head 110 has a lens 111. The lens 111 is a cylindrical component disposed on the lower surface of the laser head 110, which irradiates the processing wafer W held by the chuck 100 with a laser.

[0066] Additionally, the laser head 110 also includes a spatial light modulator (not shown). The spatial light modulator modulates the laser beam before outputting it. Specifically, the spatial light modulator can control the focal position and phase of the laser beam, thereby adjusting the shape and number (branch number) of the laser beam irradiating the processed wafer W. Furthermore, LCOS (Liquid Crystal on Silicon) can be selected as the spatial light modulator, for example.

[0067] In the formation of the internal surface modification layer M2, described later, the spatial light modulator switches the laser irradiated from the laser head 110, thereby adjusting the shape and quantity of the irradiated laser within the irradiable range of the laser L, which is determined by the size of the lens 111. Specifically, multiple focal points are simultaneously formed at multiple locations inside the processed wafer W to simultaneously form multiple internal surface modification layers M2 (multi-focal processing). Furthermore, the number of focal points formed simultaneously can be arbitrarily set according to the laser output and the energy required to form the modification layer.

[0068] Furthermore, the “irradiation range” of laser L refers to the range within the surface of the wafer W that can be irradiated by laser L at one time via the spatial light modulator; in other words, it refers to the limit range within which laser L can be irradiated by refraction through lens 111.

[0069] Furthermore, in this embodiment, the number of focal points that can be formed simultaneously by the spatial light modulator is up to four, and the irradiation range of the laser L is a 150μm square range.

[0070] Furthermore, the laser head 110 irradiates the processed wafer W with a high-frequency pulsed laser of a wavelength that is transparent to the processed wafer W by means of focusing the laser at a predetermined position inside the processed wafer W. As a result, the portion of the processed wafer W in which the laser is focused is modified to form an unbonded region Ae, a peripheral modification layer M1, an inner surface modification layer M2, and a central modification layer M3.

[0071] Furthermore, in this embodiment, to avoid complex illustrations, the unbonded area Ae, the peripheral modified layer M1, the internal surface modified layer M2, and the central modified layer M3 are formed using a common laser head 110, but they can also be formed using different laser heads. Additionally, laser heads can be used differently depending on the type of laser being irradiated.

[0072] The laser head 110 is supported by a support member 112. The laser head 110 is configured to move freely up and down along a guide rail 113 extending in the vertical direction via a lifting mechanism 114. Furthermore, the laser head 110 is configured to move freely in the Y-axis direction via a moving mechanism 115, which serves as a moving mechanism for the modified part. Both the lifting mechanism 114 and the moving mechanism 115 are supported by support columns 116.

[0073] A macro camera 120 and a microscope camera 121 are disposed above the suction cup 100 and on the positive Y-axis side of the laser head 110. For example, the macro camera 120 and the microscope camera 121 are integrated, with the macro camera 120 positioned on the positive Y-axis side of the microscope camera 121. The macro camera 120 and the microscope camera 121 are configured to be freely raised and lowered by a lifting mechanism 122, and are also configured to be freely movable along the Y-axis by a moving mechanism 123.

[0074] Macro camera 120 captures images of the outer edge of the processed wafer W (overlapping wafer T). Macro camera 120, for example, is equipped with a coaxial lens, illuminates visible light, such as red light, and also receives reflected light from the object. Furthermore, macro camera 120 has a magnification of 2x.

[0075] The image captured by the macro camera 120 is output to the control device 90. In the control device 90, a first eccentricity between the center of the chuck 100 and the center of the processed wafer W is calculated based on the image captured by the macro camera 120.

[0076] Microscope camera 121 images the periphery of the processed wafer W, specifically the boundary between the bonded region Ac and the unbonded region Ae. Microscope camera 121 includes, for example, a coaxial lens, illuminates infrared light (IR light), and also receives reflected light from the object. Furthermore, microscope camera 121 has, for example, a magnification of 10x, a field of view approximately 1 / 5 that of macro camera 120, and a pixel size approximately 1 / 5 that of macro camera 120.

[0077] The image captured by the microscope camera 121 is output to the control device 90. In the control device 90, a second eccentricity between the center of the suction cup 100 and the center of the engagement region Ac is calculated based on the image captured by the microscope camera 121. Furthermore, the control device 90 moves the suction cup 100 or the laser head 110 based on the second eccentricity to align the center of the suction cup 100 with the center of the engagement region Ac. In the following description, the control that moves the suction cup 100 or the laser head 110 is sometimes referred to as eccentricity correction.

[0078] Next, the wafer processing performed using the wafer processing system 1 configured as described above will be explained. Figure 6 This is a flowchart showing the main processes involved in wafer processing. Figure 7This is an explanatory diagram of the main processes in wafer processing. Furthermore, in this embodiment, the processing wafer W and the support wafer S are pre-bonded in a bonding device (not shown) outside the wafer processing system 1 to form a superimposed wafer T. Alternatively, the aforementioned unbonded region Ae may be pre-formed in the superimposed wafer T that is moved into the wafer processing system 1; however, in the following description, the case where the unbonded region Ae is formed using the modification device 60 will be used as an example.

[0079] First, store multiple Figure 7 The superimposed wafer T shown in (a) is placed on the box mounting stage 10 of the loading / unloading station 2.

[0080] Next, the overlapping wafer T in the wafer transfer device 20 is removed from the housing Ct and transferred to the transfer device 30. Then, the overlapping wafer T in the transfer device 30 is removed from the transfer device 50 and transferred to the modification device 60. In the modification device 60, firstly, as... Figure 7 As shown in (b), an unjoined region Ae is formed. Figure 6 Step A1). Next, as... Figure 7 As shown in (c), a peripheral modification layer M1 is formed inside the processed wafer W. Figure 6 Step A2), as follows Figure 7 As shown in (d), an internal surface modification layer M2 is formed. Figure 6 Step A3), and forming the central modified layer M3 ( Figure 6 Step A4). The peripheral modification layer M1 serves as the base point for removing the peripheral portion We during edge trimming. The inner surface modification layer M2 serves as the base point for separating the processed wafer W. The center modification layer M3 is used to control the propagation of cracks in the center of the processed wafer W and also serves as the base point for separating the center of the processed wafer W.

[0081] In the modification apparatus 60, firstly, the overlapping wafer T is transported into the modification apparatus 60 by the wafer transport device 50 and held in the chuck 100. Next, the chuck 100 is moved to the formation position of the unbonded region Ae. The formation position of the unbonded region Ae is the position where the laser head 110 can irradiate the peripheral portion We of the processed wafer W with a laser.

[0082] Next, while rotating the suction cup 100 circumferentially, a laser L (e.g., a CO2 laser) is irradiated from the laser head 110 to form an unbonded region Ae. Figure 6 (Step A1). Furthermore, as described above, the unbonded region Ae can be formed at any location near the bonding interface, as long as it can reduce the bonding strength between the processing wafer W and the supporting wafer S.

[0083] Here, when the center of the chuck 100 is not aligned with the center of the processing wafer W held on the chuck 100, the unbonded region Ae is formed eccentrically relative to the processing wafer W. That is, the center of the processing wafer W is not aligned with the center of the unbonded region Ae (bonded region Ac).

[0084] Next, the suction cup 100 is moved to the macro alignment position. The macro alignment position is the position where the macro camera 120 can capture images of the outer edge of the processed wafer W.

[0085] Next, the macro camera 120 captures images of the outer edge of the processed wafer W in a 360-degree circumferential direction. The captured images are then output from the macro camera 120 to the control device 90.

[0086] In the control device 90, a first eccentricity between the center of the suction cup 100 and the center of the processed wafer W is calculated based on the image from the macro camera 120. Furthermore, the control device 90 calculates the movement amount of the suction cup 100 based on the first eccentricity to correct the Y-axis component of this first eccentricity. The suction cup 100 moves along the Y-axis based on this calculated movement amount to move the suction cup 100 to a microscopic alignment position. The microscopic alignment position is the position where the microscope camera 121 can capture images of the peripheral portion of the processed wafer W. Here, as described above, the field of view of the microscope camera 121 is small, approximately 1 / 5 that of the macro camera 120. Therefore, if the Y-axis component of the first eccentricity is not corrected, sometimes the peripheral portion of the processed wafer W will not enter the field of view of the microscope camera 121, making it impossible to capture images through the microscope camera 121. Therefore, it can be said that correcting the Y-axis component based on the first eccentricity is to move the suction cup 100 to the microscopic alignment position.

[0087] Next, the boundary between the bonding region Ac and the unbonded region Ae of the processed wafer W is captured by the microscope camera 121 in a 360-degree circumferential direction. The captured image is then output from the microscope camera 121 to the control device 90.

[0088] In the control device 90, a second eccentricity between the center of the suction cup 100 and the center of the bonding region Ac is calculated based on the image from the microscope camera 121. Furthermore, in the control device 90, the position of the suction cup 100 relative to the peripheral modified layer M1 is determined based on the second eccentricity in a manner that makes the center of the bonding region Ac coincide with the center of the suction cup 100.

[0089] Next, the chuck 100 is moved to the modification position. The modification position is the position where the laser head 110 irradiates the processed wafer W with a laser to form the peripheral modification layer M1. Furthermore, in this embodiment, the modification position is the same as the microscopic alignment position.

[0090] Next, as Figure 8 and Figure 9As shown, a laser L (e.g., a YAG laser) is irradiated from a laser head 110 to form a peripheral modification layer M1 at the boundary between the peripheral portion We and the central portion Wc of the processed wafer W. Figure 6 (Step A2). Furthermore, inside the processed wafer W, crack C1 extends from the peripheral modified layer M1 along the thickness direction of the processed wafer W. Crack C1 only extends to the surface Wa and does not reach the back side Wb.

[0091] Furthermore, the lower end of the peripheral modification layer M1 formed by the aforementioned laser L is located above the surface of the final finished processing of the separated processed wafer W. That is, the formation position is adjusted so that the peripheral modification layer M1 does not remain on the first separated wafer W1 after separation (more specifically, after the grinding process described later).

[0092] In step A2, based on the position of the suction cup 100 determined by the control device 90, the suction cup 100 is rotated by the rotation mechanism 103 and moved along the Y-axis by the moving mechanism 104, so that the center of the engagement area Ac is aligned with the center of the suction cup 100 (eccentricity correction). At this time, the rotation of the suction cup 100 and the movement in the Y-axis direction are synchronized.

[0093] Furthermore, while performing eccentricity correction on the chuck 100 (processed wafer W), a laser L is irradiated into the interior of the processed wafer W from the laser head 110. That is, while correcting the second eccentricity, a peripheral modification layer M1 is formed. In this way, the peripheral modification layer M1 is formed as a ring concentric with the bonding region Ac. In other words, when the unbonded region Ae (bonded region Ac) is formed eccentrically relative to the processed wafer W as described above, the peripheral modification layer M1 is also formed eccentrically relative to the processed wafer W. Moreover, since the peripheral modification layer M1 and the unbonded region Ae are formed concentrically, the peripheral portion We can be appropriately removed with the peripheral modification layer M1 (crack C1) as a reference point.

[0094] Furthermore, in this example, when the second eccentricity has an X-axis component, the suction cup 100 is moved along the Y-axis while being rotated to correct the X-axis component. On the other hand, when the second eccentricity does not have an X-axis component, the suction cup 100 is not rotated, but only moved along the Y-axis.

[0095] Next, as Figure 10 As shown, an internal surface modification layer M2 is formed along the surface direction by irradiating a laser L (e.g., a YAG laser) from a laser head 110. Figure 6(Step A3). At this time, based on the relative horizontal position of the laser head 110 relative to the processed wafer W, the shape and quantity of the laser L irradiated from the laser head 110 are adjusted by a spatial light modulator. Furthermore, details of the method for forming the internal surface modification layer M2 will be described later.

[0096] Furthermore, inside the processed wafer W, crack C2 extends along the surface direction from the inner surface modification layer M2. Crack C2 only extends to the radially inner side of the peripheral modification layer M1. Additionally, the lower end of the inner surface modification layer M2 formed by the aforementioned laser L is located above the surface of the separated processed wafer W after its final finishing process. That is, the formation position is adjusted so that the inner surface modification layer M2 does not remain on the first separated wafer after separation (more specifically, after the grinding process described later).

[0097] Here, when the inner surface modification layer M2 is formed at a position further radially outward than the peripheral modification layer M1, such as Figure 11 As shown, the quality of edge trimming decreases after removing the peripheral portion We. That is, the peripheral portion We may not be properly removed with the peripheral modification layer M1 (crack C1) as the reference point, resulting in a portion of the peripheral portion We remaining on the support wafer S. From this point of view, the formation position is adjusted so that the inner surface modification layer M2 is formed at a position that is radially inward than the peripheral modification layer M1.

[0098] Furthermore, preferably, when separating the processed wafer W based on the internal surface modification layer M2 as described later, the control is... Figure 12 The circumferential spacing P (pulse pitch) and radial spacing Q (indexing pitch) of the inner surface modification layer M2 are shown to ensure uniform separation within the wafer surface. Therefore, in step A3, the spacing of the inner surface modification layer M2 is adjusted by controlling the rotation speed of the chuck 100 and the frequency of the laser L. Specifically, when the radial position of the laser head 110 (the irradiation position of the laser L) is at the outer periphery of the processed wafer W, the rotation speed is slowed down, and when the radial position of the laser head 110 is at the center, the rotation speed is increased. Furthermore, when the radial position of the laser head 110 (the irradiation position of the laser L) is at the outer periphery of the processed wafer W, the frequency is increased, and when the radial position of the laser head 110 is at the center, the frequency is decreased.

[0099] When forming the internal surface modification layer M2 on wafer W, then, as follows: Figure 13 As shown, a central modification layer M3 is formed along the surface direction by irradiating a laser L (e.g., a YAG laser) from a laser head 110. Figure 6(Step A4). Furthermore, inside the processed wafer W, crack C3 extends along the surface direction from the central modified layer M3. The central modified layer M3 is formed in a manner in which the cracks C3 are not connected to each other and are not connected to cracks C2 (e.g., more than 10 μm apart).

[0100] Furthermore, preferably, the processing lines of the central modified layer M3 are formed in the plane of the processed wafer W in a manner that does not intersect with other modified layers (internal modified layer M2, central modified layer M3). This prevents the central modified layer M3 from overlapping with other modified layers, thereby enabling proper separation of the processed wafer W.

[0101] In step A4, the rotation of the chuck 100 (processing wafer W) is stopped, and the laser head 110 is moved horizontally (X-axis direction, Y-axis direction) above the processing wafer W while the laser head 110 irradiates the interior of the processing wafer W with laser L, thereby forming a straight central modification layer M3 along the surface direction.

[0102] In addition, when forming the central modified layer M3, the suction cup 100 can be moved in the horizontal direction instead of the laser head 110 being moved in the horizontal direction.

[0103] When the central modification layer M3 is formed on the wafer W, the overlapping wafer T is then moved out of the modification device 60 by the wafer transfer device 70.

[0104] Next, the overlapping wafer T is transferred to the processing apparatus 80 via the wafer transfer device 70. In the processing apparatus 80, firstly, during the transfer of the overlapping wafer T from the transfer arm 71 to the chuck 83, as... Figure 7 As shown in (e), the processed wafer W is separated into a first separated wafer W1 and a second separated wafer W2, with the peripheral modification layer M1 and the internal surface modification layer M2 as the base points. Figure 6 (Step A5). At this time, the peripheral portion We is also removed from the processed wafer W. Since an unbonded region Ae is formed near the bonding interface between the processed wafer W and the support wafer S, the peripheral portion We can be easily peeled off, thus allowing for proper separation of the processed wafer W.

[0105] In step A5, as Figure 14 As shown in (a), the processing wafer W is held by adsorption surface 71a of the conveying arm 71, while the supporting wafer S is held by adsorption cup 83. Then, as... Figure 14As shown in (b), with the adsorption surface 71a adsorbing and holding the back surface Wb of the processed wafer W, the conveying arm 71 is raised to separate the processed wafer W into a first separated wafer W1 and a second separated wafer W2. As described above, in step A5, the second separated wafer W2 is separated integrally from the peripheral portion We, that is, the removal of the peripheral portion We and the separation (thinning) of the processed wafer W are performed simultaneously.

[0106] Furthermore, the separated second wafer W2 can be recycled, for example, to the outside of the wafer processing system 1. Alternatively, for example, a recycling section (not shown) can be provided within the movable range of the conveyor arm 71, in which the adsorption of the second wafer W2 is released, thereby recycling the separated second wafer W2.

[0107] In this embodiment, the processed wafer W is separated in the processing apparatus 80 using the wafer transport device 70, but a separation device (not shown) for separating the processed wafer W may also be provided in the wafer processing system 1. The separation device may, for example, be arranged in a manner that is stacked with the modification device 60.

[0108] Next, the chuck 83 is moved to the machining position 80b. Furthermore, the grinding unit 84 processes the material... Figure 7 As shown in (f), the back surface W1b of the first separated wafer W1, which is held by the chuck 83 as the separation surface, is ground to remove the peripheral modified layer M1, the inner surface modified layer M2, and the central modified layer M3 remaining on the back surface W1b. Figure 6 Step A6). In step A6, the first discrete wafer W1 and the grinding stone are rotated while the grinding stone is in contact with the back surface W1b to grind the back surface W1b. Alternatively, a cleaning fluid nozzle (not shown) can be used to clean the back surface W1b of the first discrete wafer W1 with cleaning fluid.

[0109] Next, the overlapping wafer T is transported to the cleaning device 41 via the wafer transfer device 70. In the cleaning device 41, the back surface W1b of the first separated wafer W1, which serves as the separation surface, is brushed. Figure 6 (Step A7). In addition, the back surface W1b of the first separated wafer W1 and the back surface Sb of the support wafer S can also be cleaned together in the cleaning apparatus 41.

[0110] Next, the overlapping wafer T is transported to the etching apparatus 40 via the wafer transport device 50. In the etching apparatus 40, the back surface W1b of the first separated wafer W1, which serves as the separation surface, is wet-etched using a chemical solution. Figure 6(Step A8). Sometimes grinding marks are formed on the back surface W1b after it has been ground by the processing apparatus 80 described above. In step A8, these grinding marks can be removed by wet etching, thereby smoothing the back surface W1b.

[0111] Subsequently, the overlapping wafer T, which has undergone all processing, is transferred to the transfer device 30 via the wafer transfer device 50, and then transferred to the cassette Ct of the cassette stage 10 via the wafer transfer device 20. In this way, a series of wafer processing steps in the wafer processing system 1 are completed.

[0112] Furthermore, in the above embodiments, the processing order of steps A1 to A8 can be appropriately changed.

[0113] As a variation 1, the order of forming the peripheral modification layer M1 in step A2 and the internal surface modification layer M2 in step A3 can be interchanged. In this case, wafer processing is performed in the order of steps A1, A3, A2, and A4 to A8.

[0114] As a variation 2, the formation of the central modification layer M3 in step A4 can also be performed before the formation of the peripheral modification layer M1 in step A2. In this case, wafer processing is performed in the order of steps A1, A4, A2 to A3, and A5 to A8.

[0115] As a variation 3, the formation of the central modification layer M3 in step A4 can also be performed before the formation of the inner surface modification layer M2 in step A3. In this case, wafer processing is performed in the order of steps A1 to A2, step A4, step A3, and steps A5 to A8.

[0116] As a variation 4, the formation of the unbonded region Ae in step A1 can also be performed after the formation of the peripheral modification layer M1 in step A2. In this case, wafer processing is performed in the order of steps A2, A1, and A3 to A8.

[0117] As a variation 5, the formation of the unbonded region Ae in step A1 can also be performed after the formation of the inner surface modification layer M2 in step A3. In this case, wafer processing is performed in the order of steps A2 to A3, step A1, and steps A4 to A8.

[0118] Furthermore, in the above embodiments, steps A1 to A8 can be appropriately omitted.

[0119] As an example of omission 1, the peripheral modification layer M1, the inner surface modification layer M2, and the central modification layer M3 of step A6 can be removed by wet etching in step A8. In this case, the grinding process of step A6 can be omitted.

[0120] As an example of omission 2, if the peripheral modification layer M1, the inner surface modification layer M2 and the central modification layer M3 are properly removed in the grinding process of step A6 and no grinding marks are formed, the wet etching of step A8 can be omitted.

[0121] As an example of omission 3, when a superimposed wafer T with an unbonded region Ae is moved into the wafer processing system 1, the formation of the unbonded region Ae in step A1 can be omitted.

[0122] Furthermore, in cases where the unbonded region Ae is formed after the alignment of the processed wafer W in the modification apparatus 60, as in variations 4 and 5 described above, the aforementioned micro-alignment (calculating the second eccentricity between the center of the chuck 100 and the bonding region Ac by photographing the boundary of the unbonded region Ae) can be omitted. In this case, the formation of the peripheral modification layer M1 in step A2 can be performed based on the results of the micro-alignment.

[0123] Furthermore, in step A5 of the above embodiment, the second separated wafer W2 is integrally separated from the peripheral portion We, that is, the removal of the peripheral portion We and the thinning of the processed wafer W are performed simultaneously. However, it is also possible not to separate the second separated wafer W2 from the peripheral portion We simultaneously. For example, the second separated wafer W2 can be separated after the peripheral portion We is peeled off by edge trimming. In this case, the crack C1 extending from the peripheral modification layer M1 formed in step A2 is as follows: Figure 15 As shown in (a), it reaches the surface Wa and the back surface Wb, thereby enabling it to reach the surface Wa and the back surface Wb as shown in (a), thereby enabling it to reach the surface Wa and the back surface Wb as shown in (a). Figure 15 As shown in (b), edge trimming and thinning are performed appropriately. Additionally, the case where the peripheral portion We is not stripped is also considered. In this case, the boundary between the bonding region Ac and the unbonded region Ae can be replaced, and the alignment of the processed wafer W can be performed based on the outer end of the processed wafer W.

[0124] Next, the method for forming the internal surface modification layer M2 in step A3 will be explained. Figure 16 This is a flowchart illustrating the main processes involved in forming the internal surface modification layer M2. Figure 17 This is an illustration of the laser irradiation conditions adjusted by a spatial light modulator during the formation of the internal surface modification layer M2. Furthermore, in the processed wafer W, a peripheral modification layer M1 and a crack C1 have already been formed before the formation of the internal surface modification layer M2. Figure 6 and Figure 16 Step A2).

[0125] As described above, it is desirable for the inner surface modification layer M2 to be formed further radially inward than the peripheral modification layer M1 to suppress the degradation of edge trimming quality. However, as previously mentioned, if the peripheral modification layer M1 is formed eccentrically relative to the processing wafer W, and the aforementioned first and second eccentricity corrections are not properly performed, the inner surface modification layer M2 may not be properly formed if this eccentricity is not considered. Specifically, edge trimming accuracy may decrease due to its formation radially outward of the peripheral modification layer M1 as described above, or separation may not be properly achieved if the inner surface modification layer M2 is not formed on the entire surface of the processing wafer W.

[0126] Furthermore, the internal surface modification layer M2 is preferably formed in a spiral shape within the surface of the processed wafer W, as described later. However, when forming the spiral shape while simultaneously correcting the eccentricity, i.e., while following the eccentricity, the chuck 100 and laser head 110 need to reciprocate at high speed in the horizontal direction at the center of the processed wafer W. Under such high-speed reciprocating motion, the eccentricity correction operation may fail to keep up with the formation of the internal surface modification layer M2, resulting in resonance and a shortened guide life.

[0127] Therefore, in the formation of the internal surface modification layer M2 according to this embodiment, firstly, the eccentricity of the chuck 100 (processing wafer W) is corrected on one side of the peripheral modification layer M1 in its radially inner side, and a buffer layer B (serving as the first internal surface modification layer) is formed to absorb the eccentricity of the bonding region Ac. Figure 16 Step A3-1). The buffer layer B is formed, for example, with a processing width (e.g., 200 μm) greater than the eccentricity of the unbonded region Ae and the peripheral modified layer M1.

[0128] During the formation of buffer layer B, the configuration (interval) and quantity of lasers L irradiated from laser head 110 are adjusted by switching the spatial light modulator. Specifically, as... Figure 17 As shown in (a), four internal surface modification layers M2 are simultaneously formed inside the processed wafer W by forming multiple, for example, four focal points in the radial direction. The radial spacing Q1, which serves as the first radial spacing of the internal surface modification layers M2, is, for example, 10 μm. Furthermore, in the following description, this radial spacing is set to 10 μm, and the irradiation pattern of the laser L with four focal points arranged in the radial direction is sometimes referred to as the "first focal pattern".

[0129] Furthermore, after the chuck 100 begins to rotate, and the rotation speed is controlled (becomes uniform), the laser L is periodically irradiated into the interior of the wafer W from the laser head 110 at least once (360 degrees) while the chuck 100 (processed wafer W) rotates, thereby forming an annular internal surface modification layer M2. Then, the laser head 110 is moved radially inward (in the Y-axis direction) relative to the wafer W. The formation of the annular internal surface modification layer M2 and the radial inward movement of the laser head 110 are repeated to form the internal surface modification layer M2 in the surface direction with the aforementioned processing width, thereby forming an internal surface modification layer M2 as a buffer layer B, concentric with the unbonded area Ae and the peripheral modification layer M1.

[0130] Furthermore, the frequency of the laser L used to form the buffer layer B is, for example, 80 kHz. Moreover, these conditions related to the formation of the internal surface modification layer M2 are examples of conditions that can be arbitrarily changed.

[0131] When the buffer layer B is formed, a spiral-shaped internal surface modification layer M2, serving as a second internal surface modification layer, is then formed, for example, from between the processing widths of the buffer layer B. During the formation of this spiral-shaped internal surface modification layer M2, the aforementioned eccentricity correction is not performed. That is, in this embodiment, eccentricity correction is performed while forming the peripheral modification layer M1 and the internal surface modification layer M2 constituting the buffer layer B, and eccentricity correction is not performed during the formation of the spiral-shaped internal surface modification layer M2 formed radially inward of the buffer layer B.

[0132] Furthermore, when forming the spiral-shaped internal surface modification layer M2, such as Figure 18 As shown, regions with different radial spacing Q are formed in the internal surface modification layer M2 to appropriately separate the processed wafer W. Specifically, a wide-spacing region R1 is formed as the region where the first modification layer is formed. Figure 16 Step A3-2) and the narrow-spaced region R2, which forms the second modified layer region Figure 16 In step A3-3), the wide-spaced region R1 is a spaced region with a radial spacing Q of the inner surface modification layer M2, formed on the radially outer side of the processed wafer W. The narrow-spaced region R2 is a spaced region with a radial spacing Q of the inner surface modification layer M2, formed on the radially inner side of the wide-spaced region R1. Furthermore, in both the wide-spaced region R1 and the narrow-spaced region R2, the circumferential spacing P of the inner surface modification layer M2 is fixed throughout the entire circumference.

[0133] Here, in the wide-interval region R1, as Figure 18 As shown in (b), the radial spacing Q2 of the inner surface modification layer M2, which serves as the second radial spacing, is set to a spacing such that the cracks C2 extending along the surface direction during the formation of adjacent outer peripheral modification layers M2e are not connected to each other. Furthermore, in the narrow spacing region R2, as... Figure 18As shown in (b), the radial spacing Q3 of the inner surface modification layer M2, which serves as the third radial spacing, is set to a spacing that connects the cracks C2 extending along the surface direction when adjacent inner peripheral side modification layers M2c are formed. Furthermore, as an example, the radial spacing Q2 of the inner surface modification layer M2 in the wide-spacing region R1 can be set to 60 μm, and the radial spacing Q3 of the inner surface modification layer M2 in the narrow-spacing region R2 can be set to 10 μm.

[0134] Similarly, when forming the wide-spaced region R1, the configuration (space) and quantity of the laser L irradiated from the laser head 110 are adjusted by switching the spatial light modulator. Here, when forming the wide-spaced region R1, it is also preferable to form four internal surface modification layers M2 radially, similar to when forming the buffer layer B. However, as described above, the range of laser L that can be irradiated by the spatial light modulator is a 150 μm square area. That is, with a radial spacing Q2 (60 μm) in the wide-spaced region R1, it is impossible to simultaneously form four radially arranged internal surface modification layers M2.

[0135] Therefore, in this embodiment, as Figure 17 As shown in (b), a total of four internal surface modification layers M2 are simultaneously formed inside the processed wafer W, two radially and two circumferentially. The radial spacing Q2 of the internal surface modification layers M2 is, for example, 60 μm, and the circumferential spacing P is, for example, 10 μm. Furthermore, in the following description, the radial spacing is set to 60 μm and the circumferential spacing is set to 10 μm. Sometimes, the irradiation pattern of the laser L that arranges the four focusing points into an approximately quadrilateral shape is referred to as the "second focusing pattern".

[0136] Furthermore, while rotating the chuck 100 relative to the laser head 110 via the rotation mechanism 103, laser L is periodically irradiated into the interior of the processed wafer W from the laser head 110, and the chuck 100 is moved along the Y-axis via the moving mechanism 104 to form an internal surface modification layer M2 along the surface direction. As a result, a spiral internal surface modification layer M2 is formed on the radially inner side of the peripheral modification layer M1.

[0137] Furthermore, the rotational speed of the processing wafer W when forming the wide-spaced region R1 is, for example, 600 rpm, and the frequency of the laser L is, for example, 80 kHz.

[0138] Here, it is desirable to make the formation spacing of the inner surface modification layer M2 uniform, as described above, so as to uniformly separate the processed wafer W within the plane. However, when forming the inner surface modification layer M2, if the rotation speed of the chuck 100 and the frequency of the laser L are controlled to be fixed, a critical point is reached where the circumferential spacing P of the inner surface modification layer M2 cannot be controlled to be fixed. Moreover, if the irradiation position of the laser L is further moved radially inward in this state, the circumferential spacing P sometimes becomes smaller, causing the inner surface modification layers M2 to overlap on the same processing line. Furthermore, when the inner surface modification layer M2 is formed overlapping in this way, sometimes the processed wafer W cannot be properly separated, or laser leakage occurs, causing damage to the device layer D.

[0139] Furthermore, when the inner surface modification layer M2 is formed by the second focusing pattern described above, the frequency of the laser L is essentially twice the rotational speed of the processed wafer W, and the position at which the critical point is reached is further radially outward than the position when the focusing point of the laser L is arranged radially.

[0140] Therefore, when the critical point of the second focusing pattern is reached in forming the wide-spacing region R1, the configuration (spacing) and quantity of the laser L irradiated from the laser head 110 are adjusted by switching the spatial light modulator. Specifically, as Figure 17 As shown in (c), multiple, for example, three focal points are formed radially inside the processed wafer W to simultaneously form three internal surface modification layers M2. The radial spacing Q2 of the internal surface modification layers M2 is, for example, 60 μm. Furthermore, in the following description, this radial spacing is set to 60 μm, and the irradiation pattern of the laser L with three focal points arranged radially is sometimes referred to as the "third focal pattern".

[0141] Furthermore, the formation range of the wide-spacing region R1 and the narrow-spacing region R2 can be arbitrarily determined. If the critical point of the second focusing pattern mentioned above does not exist within the formation range of the wide-spacing region R1, the formation of the internal surface modification layer M2 by the third focusing pattern can be omitted.

[0142] When a wide-spaced region R1 is formed, the configuration (space) and quantity of lasers L irradiated from the laser head 110 are then adjusted by switching the spatial light modulator, thereby initiating the formation of a narrow-spaced region R2. Specifically, as Figure 17 As shown in (d), multiple, for example, four focusing points are formed radially inside the processed wafer W, thereby simultaneously forming four internal surface modification layers M2. The radial spacing Q3 of the internal surface modification layers M2 is, for example, 10 μm. That is, the narrow-spacing region R2 is formed in the same way as the buffer layer B through the "first focusing pattern".

[0143] Furthermore, the frequency of the laser L used to form the narrow-spacing region R2 is, for example, 70 kHz. The narrow-spacing region R2 is formed radially inside the wide-spacing region R1 as described above. By reducing the frequency of the laser L in this way, the circumferential spacing P of the formed inner-surface modification layer M2 can be controlled to be fixed within the surface of the processed wafer W. Alternatively, the circumferential spacing P of the inner-surface modification layer M2 can be controlled by either reducing the frequency of the laser L or simultaneously increasing the rotational speed of the chuck 100.

[0144] However, when the rotational speed of the chuck 100 reaches its upper limit and the frequency of the laser L reaches its lower limit, the circumferential spacing P of the inner surface modification layer M2 reaches a critical value at which it can no longer be increased. Moreover, if the irradiation position of the laser L is further moved radially inward in this state, the circumferential spacing P may sometimes become smaller, causing the inner surface modification layer M2 to overlap on the same processing line at the center of the processed wafer W.

[0145] Therefore, the formation of the narrow-spaced region R2, i.e., the formation of the internal surface modification layer M2, ends near the center of the processed wafer W when the circumferential spacing P of the internal surface modification layer M2 reaches the final critical point. Figure 17 As shown in (e), a central modified layer M3 is formed radially inside the internal surface modified layer M2. Figure 6 and Figure 16 Step A4). Furthermore, the formation range R3 of the central modified layer M3 can be determined, for example, based on the minimum value of the laser L frequency and the maximum value of the chuck 100 rotation speed (for example, a range of about 1 to 2 mm from the center of the processed wafer W).

[0146] Furthermore, as long as the processing lines of the central modified layer M3 are formed in a manner that does not intersect or approach each other, as described above, they can be formed into any shape (straight line shape, curved shape, or a combination of both).

[0147] The internal surface modification layer M2 in step A3 is formed as described above.

[0148] According to the above embodiment, by simultaneously forming multiple internal surface modification layers M2 when forming the internal surface modification layer M2 of the processed wafer W, the productivity of the modification apparatus 60 can be increased, thereby improving productivity (production cycle time).

[0149] In addition, the laser focusing pattern of the laser L for the processed wafer W is selected and controlled according to the radial position of the laser head 110 relative to the processed wafer W, thereby enabling a more appropriate increase in production cycle time.

[0150] Furthermore, more specifically, the laser focusing pattern can be arbitrarily selected based on conditions such as the relative rotational speed of the chuck 100 (processing wafer W) at the laser focusing position, the laser frequency, and the size of the lens 111, which determine the allowable radial and circumferential irradiation ranges of the laser, as well as the maximum number of laser beams that can be irradiated. In other words, the laser focusing pattern can be selected based on the relative rotational speed of the chuck 100 (processing wafer W) at the laser focusing position and the irradiation spacing of the laser L, i.e., the circumferential spacing P forming the internal surface modification layer M2.

[0151] For example, multiple focusing points are arranged circumferentially on the outer periphery of the suction cup 100 where the rotational speed is slow, to improve productivity related to the formation of the internal surface modification layer M2. The number of these circumferentially arranged focusing points is determined by the rotational speed of the suction cup 100. Furthermore, in cases where there is a possibility that the internal surface modification layer M2 may overlap circumferentially due to an increase in rotational speed, the number of circumferentially arranged focusing points is reduced and the number arranged radially is increased. In this way, the number of internal surface modification layers M2 formed in a single step can be maximized based on the relative rotational speed of the suction cup 100 and the laser irradiation spacing, thereby improving productivity.

[0152] Furthermore, when forming the internal surface modification layer M2, the more laser beams are simultaneously focused, that is, the more internal surface modification layers M2 are formed simultaneously, the more efficiently the internal surface modification layer M2 can be formed, thereby increasing productivity.

[0153] Furthermore, the laser focusing pattern is not limited to the above-described embodiment; for example, multiple lasers may be arranged only circumferentially. When multiple lasers are arranged radially, the rotational speed of the processed wafer W can be controlled to be fixed regardless of the radial position of the laser head 110. On the other hand, when multiple lasers are arranged circumferentially, the rotational speed of the processed wafer W can be increased to form the internal surface modification layer M2.

[0154] Furthermore, as described above, the maximum number of laser irradiations is determined based on the laser output, thus enabling the internal surface modification layer M2 to be formed in any pattern based on this maximum number of irradiations.

[0155] Furthermore, in the above embodiment, the laser frequency is controlled at 80 kHz during the formation of the buffer layer B and the wide-spacing region R1, and at 70 kHz during the formation of the narrow-spacing region R2, but the laser frequency is not limited to these values. For example, the laser frequency can be controlled to continuously vary according to the radial position of the laser head 110 or the relative rotational speed of the processed wafer W at the laser focusing point. Additionally, while the frequency of the laser L is varied in the above embodiment, the rotational speed of the chuck 100 (processed wafer W) can also be varied.

[0156] Furthermore, as described above, in this embodiment, when forming the spiral-shaped internal surface modification layer M2 (wide-spacing region R1, narrow-spacing region R2), the configuration (spacing) and quantity of the laser L irradiated from the laser head 110 are adjusted by switching the spatial light modulator. Specifically, when forming the spiral-shaped internal surface modification layer M2, the internal surface modification layer M2 is formed on the entire surface of the processed wafer W while switching multiple focusing patterns.

[0157] Here, when switching the laser focusing pattern, there is a delay time from when the control device 90 sends a system signal until the laser from the laser head 110 is actually switched. Furthermore, when forming the internal surface modification layer M2, the focusing pattern is switched while the processing wafer W is rotated, as described above. Therefore, when controlling the alignment of the focusing pattern switching position with the critical point, the rotation of the processing wafer W during the aforementioned delay time must be taken into account. That is, the system signal needs to be sent before the laser head 110 reaches above the desired laser switching position.

[0158] Furthermore, in the case where the internal surface modification layer M2 is formed in a spiral shape, the circumferential spacing P (pulse pitch) of the formed internal surface modification layer M2 is fixed. Therefore, the rotation speed of the chuck 100 and the frequency of the laser are controlled according to the position of the laser head 110 relative to the processed wafer W. In other words, the rotation speed varies depending on various conditions such as the laser switching position, so the amount of movement generated by the rotation of the processed wafer W during the delay time may vary.

[0159] Therefore, when controlling the laser focusing pattern related to the formation of the internal surface modification layer M2 as described above, it is preferable to control the timing of laser switching based on the rotation speed and delay time of the processed wafer W at the laser focusing position.

[0160] Furthermore, according to the above embodiments, the internal surface modification layer M2 is formed along the surface direction of the processed wafer W in a manner that forms wide-spaced regions R1 and narrow-spaced regions R2. However, radial spacing Q can also be uniformly formed throughout the entire surface of the processed wafer W. Specifically, for example, a spiral internal surface modification layer M2 can be formed with radial spacing Q1 of the internal surface modification layer M2 in the buffer layer B. In this way, when the radial spacing Q is uniform throughout the entire surface of the processed wafer W, the separation of the processed wafer W can be performed uniformly within the surface.

[0161] Furthermore, according to the above embodiments, the inner surface modification layer M2 is formed in a spiral shape within the surface of the processed wafer W. However, the shape of the inner surface modification layer M2 is not limited to this, and it can also be formed as a ring concentric with the unbonded region Ae and the peripheral modification layer M1.

[0162] In this case, regarding the internal surface modification layer M2, the internal surface modification layer M2 is formed in the surface direction by repeatedly forming the annular internal surface modification layer M2 and moving the laser head 110 radially inward.

[0163] Furthermore, according to the above embodiment, the wide-spacing region R1 is formed on the radially outer side, and the narrow-spacing region R2 is formed on the radially inner side, but it can also be done as follows: Figure 19 As shown in (a), when viewed from above, a narrow-spaced region R2 is formed on the radially outer side of the processed wafer W, and a wide-spaced region R1 is formed on the inner side of the narrow-spaced region R2. Additionally, for example, as... Figure 19 As shown in (b), wide-spaced regions R1 and narrow-spaced regions R2 can also be alternately formed on the radially outer side of the processed wafer W.

[0164] Furthermore, in the above embodiment, wide-spaced regions R1 and narrow-spaced regions R2 are formed radially on the processed wafer W, i.e., the radial spacing Q of the internal surface modification layer M2 is changed. However, the circumferential spacing P (pulse pitch) can also be changed instead. Alternatively, both the radial spacing Q and the circumferential spacing P can be changed. In this case, the number of internal surface modification layers M2 formed within the surface of the processed wafer W is further reduced, thus further improving productivity.

[0165] The embodiments disclosed herein should be considered illustrative in all respects, not restrictive. The above embodiments can be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0166] For example, in the above embodiment, the case where the processing wafer W, as the processing object, is a silicon wafer, has been described as an example, but the type of processing object is not limited to this. For example, instead of a silicon substrate, a glass substrate, a single-crystal substrate, a polycrystalline substrate, or an amorphous substrate may be selected as the processing object. In addition, for example, instead of a circular substrate, an ingot, a platform, or a thin plate may be selected as the processing object.

[0167] For example, in the above embodiment, the processed wafer W is separated based on the peripheral modification layer M1 and the internal surface modification layer M2, but the basis for separating the processed wafer W is not limited to this. For example, the modification layer may be formed by irradiating the entire interior surface of the oxide film Fw or the oxide film Fs with a laser, and the processed wafer W may be separated starting from this modification layer. Alternatively, for example, an oxide film (not shown) may be formed between the processed wafer W and the device layer D in the processed wafer W before processing by the wafer processing system 1, and the modification layer may be formed by irradiating the entire interior surface of the oxide film with a laser, and the processed wafer W may be separated starting from this modification layer. Furthermore, for example, an adhesive layer (not shown) may also be formed at the interface between the processed wafer W and the support wafer S, and the modification layer may be formed by irradiating the entire interior surface of the adhesive layer with a laser, and the processed wafer W may be separated starting from this modification layer. In addition, the modification layer used to separate the processed wafer W includes sublimation caused by laser ablation, etc.

[0168] Explanation of reference numerals in the attached figures

[0169] 60: Modification device; 90: Control device; 100: Suction cup; 103: Rotation mechanism; 104: Moving mechanism; 110: Laser head; 115: Moving mechanism; L: Laser; M1: Peripheral modification layer; M2: Internal surface modification layer; W: Processed wafer.

Claims

1. A processing apparatus for processing an overlapping substrate formed by bonding a first substrate and a second substrate, the processing apparatus comprising: A holding section holds the overlapping substrate; A lens for irradiating the overlapping substrate with a laser; A moving mechanism that moves the holding part and the focusing point of the laser relative to each other in the horizontal direction; A rotating mechanism that causes the holding part and the lens to rotate relative to each other; and The control unit controls the formation of the focusing point on the overlapping substrate. in, While rotating the overlapping substrate held in the holding portion relative to the lens via the rotation mechanism, laser light is periodically irradiated from the lens onto the overlapping substrate, and the focusing point of the laser light is radially moved relative to the holding portion via the moving mechanism to form the focusing point. When the laser irradiation position is located at the outer periphery of the overlapping substrate, compared to when the laser irradiation position is located at a position on the overlapping substrate that is radially inward relative to the outer periphery, the control unit slows down the relative rotational speed of the holding part relative to the lens or increases the frequency of the laser. The control unit controls the number and arrangement of the focusing points formed simultaneously at different positions in the surface direction of the overlapping substrate based on the relative rotational speed of the overlapping substrate and the irradiation spacing of the laser.

2. The processing apparatus according to claim 1, characterized in that, The focusing points form a modified layer. The modified layer includes: A first modified layer, formed radially, serves as the base point for the peeling of the first substrate from the second substrate; and The second modified layer is formed radially inside the first modified layer, serving as the base point for the peeling of the first substrate from the second substrate. When the first modified layer is formed, the control unit controls the formation action of the modified layer to simultaneously form multiple first modified layers in the radial direction.

3. The processing apparatus according to claim 2, characterized in that, The control unit controls the formation of the modified layer to simultaneously form multiple first modified layers at a first radial interval. When forming the second modified layer, the control unit controls the formation operation of the modified layer to simultaneously form multiple second modified layers along the radial direction at a second radial interval larger than the first radial interval.

4. The processing apparatus according to claim 2, characterized in that, The control unit controls the formation of the modified layer to simultaneously form multiple first modified layers at a first radial interval. When forming the second modified layer, the control unit controls the formation operation of the modified layer to simultaneously form a plurality of the second modified layers at the first radial interval along the radial direction.

5. The processing apparatus according to any one of claims 2 to 4, characterized in that, The control unit controls the formation of the modified layer to simultaneously form multiple second modified layers along the circumferential direction. Furthermore, the circumferential spacing of the second modified layer formed simultaneously is the same as the circumferential spacing of the first modified layer.

6. The processing apparatus according to claim 2, characterized in that, The control unit controls the formation of the modified layer to simultaneously form multiple first modified layers at a first radial interval. During the formation of the second modified layer, the control unit controls the formation operation of the modified layer to form the first modified layer formation region and the second modified layer formation region. The first modified layer forming region is a modified layer forming region in which multiple second modified layers are simultaneously formed at a second radial interval that is larger than the first radial interval. The second modified layer forming region is a modified layer forming region in which multiple second modified layers are formed simultaneously at a third radial interval smaller than the second radial interval.

7. The processing apparatus according to any one of claims 2 to 4, characterized in that, The second modified layer is formed in a spiral shape along the surface direction.

8. The processing apparatus according to any one of claims 2 to 4, characterized in that, The second modified layer is formed into a concentric ring along the surface direction.

9. A processing method for processing an overlapping substrate formed by bonding a first substrate and a second substrate, wherein in the processing method, While rotating the overlapping substrate held in the holding part relative to the lens for irradiating the laser via a rotating mechanism, periodically irradiating the overlapping substrate from the lens, and moving the laser relative to the holding part in the radial direction via a moving mechanism to form a focusing point. When the laser irradiation position is located at the outer periphery of the overlapping substrate, compared to when the laser irradiation position is located at a position on the overlapping substrate that is radially inward relative to the outer periphery, the relative rotational speed of the holding part relative to the lens is slowed down or the frequency of the laser is increased. The number and arrangement of the focusing points formed simultaneously at different positions in the surface direction of the overlapping substrate are determined based on the relative rotational speed of the overlapping substrate and the irradiation spacing of the laser.

10. The processing method according to claim 9, characterized in that, The focusing points form a modified layer. The processing method includes: A first modified layer is formed radially to serve as the base point for the separation of the first substrate and the second substrate; and A second modified layer is formed radially inside the first modified layer, serving as the base point for the peeling of the first substrate from the second substrate. When forming the first modified layer, multiple first modified layers are formed simultaneously in the radial direction.

11. The processing method according to claim 10, characterized in that, Multiple first modified layers are simultaneously formed along the radial direction at first radial intervals. When forming the second modified layer, multiple second modified layers are formed simultaneously along the radial direction at a second radial interval larger than the first radial interval.

12. The processing method according to claim 10, characterized in that, Multiple first modified layers are simultaneously formed radially at first radial intervals. When forming the second modified layer, a plurality of the second modified layers are formed simultaneously along the radial direction at the first radial interval.

13. The processing method according to any one of claims 10 to 12, characterized in that, Multiple second modified layers are simultaneously formed along the circumferential direction at circumferential intervals of the first modified layer.

14. The processing method according to claim 10, characterized in that, Multiple first modified layers are simultaneously formed radially at first radial intervals. The formation of the second modified layer includes: A first modified layer forming region is formed, wherein a plurality of second modified layers are simultaneously formed at a second radial spacing larger than the first radial spacing; and A second modified layer forming region is formed, which is a modified layer forming region in which multiple second modified layers are formed simultaneously at a third radial interval smaller than the second radial interval.

15. The processing method according to any one of claims 10 to 12, characterized in that, When forming the second modified layer, While rotating the overlapping substrate held in the holding portion relative to each other, the laser is periodically irradiated and the laser is moved relative to the holding portion in the radial direction to form the second modified layer in a spiral manner along the surface direction.

16. The processing method according to any one of claims 10 to 12, characterized in that, When forming the second modified layer, The second modified layer is formed in a ring shape. Then, the laser is moved radially relative to the holding part. The formation of the annular second modified layer and the radial movement of the laser are repeated to form the second modified layer in a concentric annular shape in the planar direction.

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