Substrate processing method and substrate processing system

Abstract

To properly remove the edge portion of a first substrate in consideration of a non-joint region in a notch portion formed on the first substrate, in a polymeric substrate.SOLUTION: There is provided a substrate processing method for processing a polymeric substrate where a first substrate and a second substrate are joined to each other. The first substrate includes: a notch Wn formed by cutting a part of the peripheral edge portion of the first substrate to be removed; a joint region Ac that is joined to the second substrate; and a non-joint region Ae that is not joined to the second substrate. The substrate processing method includes: forming a first peripheral edge modifying layer M1, which serves as a starting point of peeling of a peripheral edge portion, by laser light radiation along the boundary Ad between the peripheral edge portion of the first substrate and the central portion of the first substrate; and irradiating the first peripheral edge modifying layer with laser light on a radially outer side to form a second peripheral edge modifying layer M2 which serves as a starting point of a bonding force reduction region where bonding force in the joint region is reduced. When the first peripheral edge modifying layer is formed, the formation position of the first peripheral edge modifying layer and the second edge modifying layer corresponding to the formation portion of the notch is determined based on information about the non-joint region.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing system. [Background technology]

[0002] Patent Document 1 discloses a substrate processing system for processing a laminated substrate formed by bonding a first substrate and a second substrate. The substrate processing system disclosed in Patent Document 1 includes a modified layer forming device that forms a modified layer inside the first substrate along the boundary between the peripheral edge and the center of the peripheral edge of the first substrate to be removed, and a peripheral edge removing device that removes the peripheral edge using the modified layer as a base point. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-97506 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure appropriately removes the peripheral edge of a first substrate in a laminated substrate formed by bonding a first substrate and a second substrate, taking into consideration the unbonded region in a notch formed in the first substrate. [Means for solving the problem]

[0005] One aspect of the present disclosure is a substrate processing method for processing an overlapped substrate formed by bonding a first substrate and a second substrate, wherein the first substrate has a notch formed by cutting out a portion of the peripheral portion of the first substrate to be removed, a bonded portion bonded to the second substrate, and an unbonded portion not bonded to the second substrate, the method including: irradiating laser light along the boundary between the peripheral portion of the first substrate and a central portion of the first substrate to form a first peripheral modified layer that serves as a base point for peeling off the peripheral portion; and irradiating laser light radially outward from the first peripheral modified layer to form a second peripheral modified layer that serves as a base point for a bonding strength reduction region that reduces the bonding strength at the bonded portion, and when forming the first peripheral modified layer, the formation positions of the first peripheral modified layer and the second peripheral modified layer corresponding to the formation portion of the notch are set based on information about the unbonded portion. [Effects of the Invention]

[0006] According to the present disclosure, in a laminated substrate in which a first substrate and a second substrate are bonded together, the peripheral portion of the first substrate can be appropriately removed, taking into account the unbonded area in the notch portion formed in the first substrate. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is an enlarged side view showing a configuration example of an overlapping wafer according to an embodiment. [Figure 2] 1 is an explanatory diagram showing a configuration example of an overlapping wafer according to an embodiment in a plan view. FIG. [Figure 3] 1 is an explanatory diagram showing a configuration example of an overlapping wafer according to an embodiment in a side view. FIG. [Figure 4] 1 is a plan view showing an outline of a configuration example of a wafer processing system according to an embodiment. [Figure 5] FIG. 2 is a plan view showing an example of the configuration of a reformer. [Figure 6] FIG. 2 is a side view showing an example of the configuration of a reformer. [Figure 7] 1A to 1C are explanatory views showing main steps of wafer processing according to an embodiment. [Figure 8] FIG. 2 is an explanatory diagram showing a configuration example of a divided modified layer according to an embodiment. [Figure 9] FIG. 2 is a side view showing an example of the configuration of a grinding device. [Figure 10] 1A to 1C are explanatory views showing main steps of grinding according to an embodiment. [Figure 11] FIG. 2 is an explanatory diagram showing a configuration example of a divided modified layer according to an embodiment. [Figure 12] FIG. 2 is an explanatory diagram showing a configuration example of a divided modified layer according to an embodiment. [Figure 13] FIG. 2 is an explanatory diagram showing a configuration example of a divided modified layer according to an embodiment. [Figure 14] FIG. 2 is an explanatory diagram showing a configuration example of a divided modified layer according to an embodiment. [Figure 15] FIG. 2 is a flow diagram showing the main steps of forming a first peripheral modified layer and a second peripheral modified layer according to an embodiment. [Figure 16] 10 is a graph showing the relationship between the circumferential position of the overlapping wafer and the amount of eccentricity. [Figure 17] FIG. 4 is an explanatory diagram showing a first peripheral modification layer formed by a second pattern according to the embodiment. [Figure 18] 6A and 6B are explanatory views showing an example of the configuration of a second peripheral modified layer formed in a second pattern according to an embodiment. [Figure 19] 6A and 6B are explanatory views showing an example of the configuration of a second peripheral modified layer formed in a second pattern according to an embodiment. [Figure 20] FIG. 10 is an explanatory diagram showing a first peripheral modified layer and a second peripheral modified layer formed by a third pattern according to the embodiment. [Figure 21] 10A and 10B are explanatory views showing another example of forming a first peripheral modified layer and a second peripheral modified layer using a third pattern according to the embodiment. [Figure 22] 10 is a graph showing the relationship between the circumferential position and the amount of eccentricity used in processing the overlapping wafer in the third pattern according to the embodiment. [Figure 23] 10A and 10B are explanatory views showing an example of a method for forming a first peripheral modified layer using a third pattern according to an embodiment. [Figure 24]10A and 10B are explanatory views showing an example of a method for forming a first peripheral modified layer using a third pattern according to an embodiment. [Figure 25] FIG. 3 is an explanatory diagram of the crystal orientation of the first wafer. [Figure 26] FIG. 10 is an explanatory diagram showing another example of the configuration of the first peripheral modification layer. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the manufacturing process of semiconductor devices, in a laminated wafer formed by bonding two semiconductor substrates (hereinafter referred to as "wafers"), the peripheral edge of the first wafer may be removed, that is, so-called edge trimming may be performed.

[0009] The edge trimming of the first wafer is performed using, for example, a wafer processing system (substrate processing system) disclosed in Patent Document 1. A modified layer is formed by irradiating the inside of the first wafer (first substrate) with laser light, and the peripheral portion of the first wafer is removed from the modified layer as a base point.

[0010] The edge of the first wafer W, including the peripheral edge We to be removed by edge trimming, is chamfered, with the thickness decreasing toward the tip (see FIG. 1). Therefore, in an overlapped wafer formed by bonding the first wafer W and the second wafer S, the first wafer W and the second wafer S do not come into contact with each other at the chamfered portion where the thickness is reduced, and therefore are not bonded. Furthermore, even in the region radially inward of the chamfered portion, there may be a region where the first wafer W and the second wafer S are not bonded due to various factors, such as the results of wafer processing in a previous process or the conditions for bonding the first wafer W and the second wafer S.

[0011] In the following description, in a laminated wafer T in which a first wafer W and a second wafer S are bonded together, the portion where the first wafer W and the second wafer S are not bonded together may be referred to as an "unbonded portion," and the portion where the first wafer W and the second wafer S are bonded together may be referred to as a "bonded portion."

[0012] As described above, the unbonded portion may occur radially inward of the chamfered portion of the first wafer W. To avoid complicating the explanation, however, as shown in Figures 1 and 2, the unbonded portion corresponding to the chamfered portion may be referred to as the "unbonded region Ae," the bonded portion radially inward of the unbonded region Ae as the "bonded region Ac," and the boundary portion between the unbonded region Ae and the bonded region Ac as the "boundary Ad."

[0013] Here, a notch Wn indicating the direction of crystal orientation is formed in the peripheral edge We of the first wafer W, which is a semiconductor substrate, extending radially inward from the outer edge of the first wafer W. In the area where the notch Wn is formed, an unbonded portion is formed along the notch Wn in a planar view, as shown in FIG. 2 , and therefore an unbonded region Ae is formed radially inward compared to the area where the notch Wn is not formed. Therefore, if a fixed trim width is set from the outer edge of a wafer without a notch Wn, an unbonded portion remains in the area where the notch Wn is formed, causing the first wafer W to float from the second wafer S, which may cause chipping in a later process.

[0014] The technology disclosed herein has been made in consideration of the above circumstances, and in a laminated substrate in which a first substrate and a second substrate are bonded, the peripheral portion of the first substrate is appropriately removed, taking into account the unbonded area in a notch formed in the first substrate. Hereinafter, a wafer processing system as a substrate processing system and a wafer processing method as a substrate processing method according to this embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

[0015] 1 and 3, a wafer processing system 1 according to this embodiment, which will be described later, processes an overlapped wafer T as an overlapped substrate formed by bonding a first wafer W as a first substrate and a second wafer S as a second substrate. Hereinafter, the surface of the first wafer W that is bonded to the second wafer S will be referred to as the front surface Wa, and the surface opposite the front surface Wa will be referred to as the back surface Wb. Similarly, the surface of the second wafer S that is bonded to the first wafer W will be referred to as the front surface Sa, and the surface opposite the front surface Sa will be referred to as the back surface Sb.

[0016] The first wafer W is a semiconductor substrate such as a silicon substrate, and has a device layer Dw including a plurality of devices formed on its surface Wa. A bonding film Fw is further formed on the device layer Dw, and the first wafer S is bonded to the device layer Dw via the bonding film Fw. The bonding film Fw may be, for example, an oxide film (THOX film, SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive. As shown in FIG. 1, the peripheral edge We of the first wafer W is chamfered, and the cross section of the peripheral edge We becomes thinner toward its tip. The peripheral edge We is a portion to be removed in the edge trimming process described below, and extends, for example, from 0.5 mm to 3 mm in the radial direction from the outer edge of the first wafer W.

[0017] 2, a notch Wn indicating the crystal orientation is formed in the peripheral edge portion We of the first wafer W. In one example, the notch Wn is formed by cutting out a part of the outer edge portion of the first wafer W. The shape of the notch Wn is not limited to the substantially triangular shape shown in FIG. 2, and may be formed in, for example, a substantially elliptical shape or a substantially circular shape.

[0018] The second wafer S has, for example, the same configuration as the first wafer W, and has a device layer Ds and a bonding film Fs formed on its surface Sa, and its peripheral portion is chamfered and has a notch formed therein. Note that the second wafer S does not necessarily have to be a device wafer on which the device layer Ds is formed, and may be, for example, a support wafer that supports the first wafer W.

[0019] 4, wafer processing system 1 has a configuration in which a load / unload station 2 and a processing station 3 are integrally connected. In load / unload station 2, for example, a FOUP F capable of accommodating a plurality of overlapped wafers T is loaded and unloaded between the load / unload station 2 and the outside. Processing station 3 is equipped with various processing devices that perform desired processing on overlapped wafers T.

[0020] The carry-in / out station 2 is provided with a FOUP mounting table 10 on which a FOUP F capable of accommodating a plurality of overlapped wafers T is mounted. A wafer transfer device 20 is provided adjacent to the FOUP mounting table 10 on the positive X-axis side of the FOUP mounting table 10. The wafer transfer device 20 moves on a transfer path 21 extending in the Y-axis direction, and is configured to be able to transfer the overlapped wafers T between the FOUP F on the FOUP mounting table 10 and a transition device 30, which will be described later.

[0021] In the loading / unloading station 2, a transition device 30 for transferring the overlapped wafer T to and from the processing station 3 is provided adjacent to the wafer transfer device 20 on the positive side of the X axis of the wafer transfer device 20.

[0022] In the processing station 3, a wafer transfer device 40, a modifying device 60, an edge removing device 70, a cleaning device 80, and a grinding device 90 are arranged.

[0023] The wafer transfer device 40 is provided on the positive X-axis side of the transition device 30. The wafer transfer device 40 is configured to be movable on a transfer path 41 extending in the X-axis direction, and is configured to be able to transfer the overlapped wafer T to the transition device 30, the modifying device 60, the edge removing device 70, the cleaning device 80, and the grinding device 90 in the carry-in / out station 2.

[0024] As shown in FIGS. 5 and 6 , the modification apparatus 60 includes a chuck 100 as a substrate holder that holds the overlapped wafer T on its upper surface. The chuck 100 holds the overlapped wafer T by suction. The chuck 100 may hold the back surface Wb of the first wafer W or the back surface Sb of the second wafer S by suction. The chuck 100 is supported by a slider table 102 via an air bearing 101. A rotation mechanism 103 is provided on the lower surface of the slider table 102. The rotation mechanism 103 incorporates, for example, a motor as a drive source. The chuck 100 is configured to be rotatable about a vertical axis by the rotation mechanism 103 via the air bearing 101. The slider table 102 is configured to be movable on rails 106 that are provided on a base 105 and extend in the Y-axis direction via a movement mechanism 104 provided on the lower surface thereof. The drive source of the moving mechanism 104 is not particularly limited, but may be, for example, a linear motor. The reforming device 60 also has a control device 61, which will be described later.

[0025] In one embodiment, the slider table 102 includes another rail (not shown) extending in the X-axis direction, another moving mechanism is provided on the other rail, and the chuck 100 is supported on the other moving mechanism. In this way, the slider table 102 according to one embodiment is configured to further move the chuck 100 in the X-axis direction.

[0026] A laser head 110 is provided above the chuck 100. The laser head 110 has a lens 111. The lens 111 is a cylindrical member provided on the lower surface of the laser head 110, and irradiates the interior of the overlapped wafer T held by the chuck 100 with laser light L1. This modifies the portion of the overlapped wafer T irradiated with the laser light L1, forming a first peripheral modified layer M1 or a second peripheral modified layer M2. Note that in the technology disclosed herein, the laser head 110 and the lens 111 may be collectively referred to as the "laser irradiation unit."

[0027] The laser head 110 is supported by a support member 112. The laser head 110 is configured to be able to move up and down by an elevating mechanism 114 along rails 113 extending in the vertical direction. The laser head 110 is also configured to be able to move in the Y-axis direction by a moving mechanism 115. The elevating mechanism 114 and the moving mechanism 115 are each supported by a support column 116.

[0028] A macro camera 120 and a micro camera 121 are provided above the chuck 100, on the Y-axis positive side of the laser head 110. For example, the macro camera 120 and the micro camera 121 are configured as an integrated unit, with the macro camera 120 being disposed on the Y-axis positive side of the micro camera 121. The macro camera 120 and the micro camera 121 are configured to be able to move up and down freely by an elevator mechanism 122, and are further configured to be able to move freely in the Y-axis direction by a movement mechanism 123. Note that in the technology according to the present disclosure, the macro camera 120 and the micro camera 121 may collectively be simply referred to as the "camera."

[0029] The macro camera 120 captures an image of the outer edge of the first wafer W (polymerized wafer T). The image captured by the macro camera 120 is used, for example, for alignment of the first wafer W, which will be described later. The macro camera 120 includes, for example, a coaxial lens, irradiates infrared light (IR), and receives reflected light from an object. The imaging magnification of the macro camera 120 is, for example, 2x.

[0030] The micro camera 121 captures an image of the peripheral edge We of the first wafer W and captures an image of the boundary Ad between the bonded region Ac and the unbonded region Ae. The image captured by the micro camera 121 is used, for example, to set the irradiation position of the laser light L1. The micro camera 121 is equipped with, for example, a coaxial lens, irradiates infrared light (IR light), and receives reflected light from an object. The imaging magnification of the micro camera 121 is, for example, 10 times, the field of view is approximately 1 / 5 of that of the macro camera 120, and the pixel size is approximately 1 / 5 of that of the macro camera 120.

[0031] In the illustrated example, two cameras, a macro camera 120 and a micro camera 121, are arranged, but the number of cameras provided in the modifying device 60 is not limited to this, and any number of cameras equal to or greater than one may be arranged in the modifying device 60. For example, in cases where it is not necessary to capture an image of the boundary Ad between the bonded region Ac and the unbonded region Ae, such as when the boundary Ad is known in advance, the micro camera 121 may be omitted. Furthermore, detection of the outer edge of the first wafer W is not limited to a camera, and a displacement meter that irradiates light onto the outer edge of the first wafer W may also be used.

[0032] In the illustrated example, the chuck 100 is configured to be rotatable relative to the laser head 110 and movable in the horizontal direction by the rotation mechanism 103 and the movement mechanism 104, but the laser head 110 may be configured to be rotatable relative to the chuck 100 and movable in the horizontal direction. Alternatively, both the chuck 100 and the laser head 110 may be configured to be rotatable relative to each other and movable in the horizontal direction.

[0033] The modifying device 60 irradiates the inside of the first wafer W with laser light (internal laser light, for example, a YAG laser) to form a first peripheral modified layer M1 that serves as a base point for peeling off the peripheral portion We, a second peripheral modified layer M2 that serves as a base point for a bonding strength reduced region R that reduces the bonding strength, and divided modified layers M3 that serve as base points for dividing the peripheral portion We into small pieces. The configuration of the modifying device 60 is not particularly limited.

[0034] In the illustrated example, two modifying devices 60 are arranged inside the wafer processing system 1, but the number and arrangement of the modifying devices 60 are not limited to this.

[0035] The edge removal device 70 removes the edge portion We of the first wafer W, i.e., performs edge trimming, using the first edge modified layer M1 and the bonding strength reduced region R formed by the modification device 60 as base points. The edge trimming method can be selected arbitrarily. In one example, the edge removal device 70 may insert, for example, a wedge-shaped blade into the interface between the first wafer W and the second wafer S. Alternatively, for example, an air blow or a water jet may be sprayed toward the edge portion We to apply an impact to the edge portion We. Alternatively, for example, ultrasonic waves may be applied to the edge portion We to apply an impact to the edge portion We. Furthermore, for example, the edge portion We may be physically moved in a direction away from the center portion We. Alternatively, the edge portion We may be removed simultaneously when grinding the back surface Wb of the first wafer W using a grinding device 90, which will be described later.

[0036] The cleaning device 80 performs a cleaning process on the first wafer W and the second wafer S after the edge trimming or grinding by the edge removal device 70, thereby removing particles from these wafers. Any cleaning method can be selected.

[0037] The grinding device 90 includes a rotary table (not shown), and two chucks 131, for example, are provided on the rotary table as substrate holders for holding the overlapped wafer T by suction.

[0038] The chuck 131 according to this embodiment is held by two chuck bases 132, respectively. As shown in Fig. 9, the chuck base 132 is provided with an inclination adjustment mechanism 134 that adjusts the relative inclination between the grinding unit 140 and the chuck 131. The inclination adjustment mechanism 134 has a fixed shaft 135 provided on the lower surface of the chuck base 132 and a plurality of, for example, two, lift shafts 136. Each lift shaft 136 is configured to be extendable and retractable, and lifts and lowers the chuck base 132.

[0039] The two chucks 131 can be moved to a delivery position and a processing position by rotating a rotary table (not shown). Each of the two chucks 131 is configured to be rotatable about a vertical axis by a rotation mechanism (not shown). At the delivery position, the transfer unit delivers the overlapped wafer T.

[0040] 9, the grinding unit 140 at the processing position has an annular grinding stone 141, a grinding wheel 142 that supports the grinding stone 141, a mount 143 that supports the grinding wheel 142, a spindle 144 that rotates the grinding wheel 142 via the mount 143, and a drive unit 145 that supports the spindle 144. The drive unit 145 has a built-in motor (not shown), for example, and rotates the spindle 144. The grinding unit 140 is also configured to be movable vertically along a support column by an elevation drive unit (not shown).

[0041] The configuration of the grinding device 90 is not limited to this. For example, four chucks 131 may be provided on a rotary table, and the four chucks 131 may be configured to be movable among a transfer position for the overlapped wafer T, a rough grinding unit (not shown) that performs rough grinding of the overlapped wafer T, an intermediate grinding unit (not shown) that performs intermediate grinding of the overlapped wafer T, and a finish grinding unit (not shown) that performs finish grinding of the overlapped wafer T. Furthermore, the grinding device 90 may be provided in the wafer processing system 1 as in this embodiment, or may be provided outside the wafer processing system 1.

[0042] When removing the peripheral edge portion We using the grinding device 90, in the above-described grinding device 90, the back surface Wb of the first wafer W is ground by rotating the chuck 131 and the grinding wheel 141 while lowering the grinding wheel 141 in a state where the back surface Wb of the first wafer W is in contact with part of the arc of the grinding wheel 141 as shown in Fig. 10(a) . Then, during the grinding of the entire back surface Wb of the first wafer W, the back surface Wb of the first wafer W is ground to a target thickness while the peripheral edge portion We is removed as shown in Fig. 10(b) .

[0043] The wafer processing system 1 described above is provided with a control device 61 and at least one control device 150. The control device 61 individually controls the operation of each of the modifying devices 60. The control device 150 controls the entire series of wafer processing in the wafer processing system 1.

[0044] Controller 61 and controller 150 process computer-executable instructions that cause reformer 60 and wafer processing system 1 to perform the various steps described in this disclosure, respectively. Controller 61 and controller 150 may be configured to control elements of reformer 60 and wafer processing system 1 to perform the various steps described herein. In one embodiment, some or all of controller 61 may be included in reformer 60, and some or all of controller 150 may be included in wafer processing system 1.

[0045] The control device 61 and the control device 150 may each include a processing unit, a storage unit, and a communication interface. The control device 61 and the control device 150 may each be realized by, for example, a computer. The processing unit may be configured to read a program providing logic or routines enabling various control operations from the storage unit and execute the read program to perform various control operations. The program may be pre-stored in the storage unit or may be acquired via a medium when needed. The acquired program is stored in the storage unit and read from the storage unit and executed by the processing unit. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a central processing unit (CPU). The storage unit may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface may communicate between the modification device 60 and the wafer processing system 1 via a communication line such as a local area network (LAN).

[0046] In this embodiment, the control device 61 is installed separately from the reformer 60, but the control device 61 may be configured integrally with the control device 150. In other words, the operation of the reformer 60 may be controlled by the control device 150.

[0047] The wafer processing system 1 according to one embodiment is configured as described above, but the configuration of the wafer processing system 1 is not limited to the example shown in the figure.

[0048] Next, a description will be given of wafer processing performed using the wafer processing system 1 configured as shown in Fig. 4. In this embodiment, a first wafer W and a second wafer S are bonded together to form an overlapping wafer T in advance.

[0049] First, the FOUP F containing a plurality of overlapped wafers T is placed on the FOUP placement table 10 of the carry-in / out station 2.

[0050] Next, the overlapped wafer T is removed from the FOUP F by the wafer transfer device 20 and transferred to the modifying device 60 via the transition device 30.

[0051] By forming the second peripheral modification layer M2 and generating stress concentration regions Q1 and Q2, a similar bonding strength reduction region R is formed at the interface between the first wafer W and the second wafer S along the stress concentration regions Q1 and Q2.

[0052] In the modification device 60, as shown in FIG. 7(a) or 8, laser light L1 is irradiated onto the inside of the first wafer W to form a first peripheral modified layer M1, a second peripheral modified layer M2, and a divided modified layer M3. Note that FIG. 7(a) illustrates a region inside the first wafer W where the second peripheral modified layer M2 is formed, and FIG. 8 illustrates a region inside the first wafer W where the second peripheral modified layer M2 is not formed. Note that for ease of explanation, the divided modified layer M3 is not shown in FIG. 7(a). The first peripheral modified layer M1 serves as a base point for removing the peripheral portion We in the edge trimming process described below. The second peripheral modified layer M2 serves as a base point for stress concentration regions Q1 and Q2 described below. The divided modified layer M3 serves as a base point for dividing the peripheral portion We into small pieces. Furthermore, cracks C extend in the thickness direction of the first wafer W from the first peripheral modified layer M1 and the divided modified layer M3 formed by the irradiation of the laser light L1. Like the first peripheral modified layer M1 and the divided modified layer M3, the cracks C serve as base points when removing the peripheral portion We and when dividing the peripheral portion We into small pieces. Note that in FIG. 7 and the drawings used in the following explanation, the second peripheral modified layer M2 or the divided modified layer M3 may be omitted from illustration to avoid complicating the illustration.

[0053] A configuration example of the second peripheral modified layer M2 will be described. The second peripheral modified layer M2 is formed in the bonding region Ac or the unbonded region Ae radially outward of the first peripheral modified layer M1, near the front surface Wa of the first wafer W, so as to extend in the XY plane. Specifically, the distance H in the thickness direction between the second peripheral modified layer M2 and the front surface Wa is, for example, within 20 μm.

[0054] Furthermore, adjacent second peripheral modified layers M2 are not connected to each other. In other words, cracks from the second peripheral modified layers M2 do not reach adjacent second peripheral modified layers M2. To prevent the second peripheral modified layers M2 from connecting to each other in this way, one or both of the spacing of the laser beam L1 and the intensity of the laser beam L1 are controlled. The lower limit of the spacing of the laser beam L1, i.e., the spacing P of the second peripheral modified layers M2, is a spacing at which cracks do not connect between adjacent second peripheral modified layers M2, and the upper limit of the spacing P is a spacing at which a reduced bonding strength region R can be formed. The spacing P is, for example, 10 μm to 80 μm.

[0055] In this case, the second peripheral modified layer M2 expands, causing compressive stress to act, and tensile stress to act in the stress concentration region Q1 above the second peripheral modified layer M2 and the stress concentration region Q2 below the second peripheral modified layer M2. In other words, tensile stress accumulates in these stress concentration regions Q1 and Q2, and tensile stress acts on the surface Wa of the first wafer W. As a result, compressive stress acts on the upper portion of the first wafer W (the portion above the second peripheral modified layer M2) such that the upper portion of the first wafer W warps obliquely upward so as to peel off the peripheral portion We (indicated by the bold arrow in FIG. 7(a)). In response to this compressive stress (warpage) in the upper portion of the first wafer W, tensile stress acts on the bonding region between the bonding film Fw and the bonding film Fs, forming a bonding strength reduction region R.

[0056] If adjacent second peripheral modified layers M2 were connected by a crack, the compressive stress would be released, no tensile stress would act on the surface Wa of the first wafer W, and the bond strength reduced region R would be unlikely to be formed. The bond strength would then be reduced in the region formed by the second peripheral modified layer M2 and the crack, and the peripheral portion We would be removed from that region. In this regard, according to the present embodiment, the second peripheral modified layers M2 are not connected to each other, so the bond strength reduced region R can be formed outside the first wafer W.

[0057] Furthermore, in this embodiment, the second peripheral modification layer M2 is formed near the surface Wa of the first wafer W, so that the tensile stress acting on the surface Wa of the first wafer W increases, and a bonding strength reduction region R can be formed.

[0058] In addition, if the tensile stress acting on the bonding strength reduced region R becomes large, a part of the bonding region between the bonding film Fw and the bonding film Fs may peel off. Even in such a case, because the bonding strength reduced region R is formed to extend radially outward from the first peripheral modified layer M1, peeling of the bonding region between the bonding film Fw and the bonding film Fs does not occur radially inward from the first peripheral modified layer M1.

[0059] The second peripheral modified layer M2 may be formed as multiple layers stacked in the thickness direction of the first wafer W. In this case, the tensile stress in the bonding strength reduced region R can be increased while preventing cracks from connecting between adjacent second peripheral modified layers M2. In this case, the upper second peripheral modified layer M2 and the lower second peripheral modified layer M2 may be formed alternately so that they do not overlap in a plan view. In this case, it is possible to further prevent cracks from connecting between adjacent second peripheral modified layers M2 in the thickness direction.

[0060] In the above embodiment, the first peripheral modified layer M1 and the second peripheral modified layer M2 were formed in the reforming device 60, but these first peripheral modified layer M1 and second peripheral modified layer M2 may also be formed in different reforming devices 60.

[0061] An example of the configuration of the divided modified layer M3 will be described. In one embodiment, as shown in FIG. 11, multiple divided modified layers M3 are formed so as to extend radially outward from the first peripheral modified layer M1 (radial divided modified layers M3a in FIG. 11). In such a case, for example, when removing the peripheral edge portion We using a peripheral edge removal device 70, the peripheral edge portion We is peeled off from the first peripheral modified layer M1 as a base point and divided into multiple pieces by the radial divided modified layers M3a. In this way, the peripheral edge portion We to be removed becomes smaller, making it easier to remove.

[0062] Furthermore, for example, when the first wafer W is ground using a grinding device 90 to remove the peripheral edge portion We, a method of dividing the peripheral edge portion We (edge pieces) into small pieces may be to form multiple annular divided modified layers M3b at arbitrary intervals in a concentric direction with the first peripheral modified layer M1, as shown in FIG. 11 . In this case, the removed peripheral edge portion We can be made smaller. Furthermore, by controlling the radial intervals between the annular divided modified layers M3b, the size of the small pieces of the peripheral edge portion We to be removed can be controlled.

[0063] Furthermore, instead of the multiple annular divided modified layers M3b, divided modified layers M3c having a spiral shape in a plan view may be formed as shown in Fig. 12. In this case, in the modifying device 60, the chuck 100 or the laser head 110 is moved in the horizontal direction, and the laser head 110 is irradiated with laser light from the chuck 100 while rotating the chuck 100, thereby continuously forming the spiral divided modified layers M3c. As a result, the time required for the processing can be shortened.

[0064] Additionally, when forming a spiral-shaped divided modified layer M3c, a left-handed spiral formation portion M3L and a right-handed spiral formation portion M3R may be formed to overlap each other, as shown in FIG. 13 . In this case, in the modification device 60, the chuck 100 or the laser head 110 is moved horizontally while the chuck 100 is rotated left or right, and laser light is irradiated from the laser head 110 to the first wafer W. This allows the left-handed and right-handed spiral formation portions M3L and M3R to be continuously formed. As a result, the left-handed and right-handed spiral formation portions M3L and M3R intersect with each other, thereby reducing the area surrounded by them in a plan view. This further reduces the removed peripheral edge portion We. Note that while FIG. 13 illustrates the left-handed and right-handed spiral formation portions M3L and M3R separately, this is for ease of illustration; they are formed to overlap the peripheral edge portion We of the same wafer W. Along with the spiral forming portions M3L and M3R, radially divided modified layers M3a may be formed.

[0065] Furthermore, when forming a spiral-shaped divided modified layer M3c, two spiral formation portions M3P and M3Q with different periods (number of turns) may be formed by overlapping them, as shown in FIG. 14. For example, as shown in FIG. 14, the spiral formation portion M3P has two and a half turns, while the formation portion M3Q has one and a half turns. In this case, in the modification device 60, the spiral formation portions M3P and M3Q with different numbers of turns can be formed by irradiating the first wafer W with laser light from the laser head 110 while moving the chuck 100 or the laser head 110 horizontally. As a result, the spiral formation portions M3P and M3Q with different numbers of turns intersect with each other, thereby reducing the area surrounded by them in a plan view. This further reduces the removed peripheral edge portion We. Note that although the two spiral formation portions M3P and M3Q are shown separately in FIG. 14 for ease of illustration, they are formed overlapping the peripheral edge portion We of the same wafer W. Along with the spiral forming portions M3P and M3Q, radially divided modified layers M3a may be formed.

[0066] The detailed method for forming the first peripheral modified layer M1 and the second peripheral modified layer M2 in the reforming device 60 will be described later.

[0067] The overlapped wafer T, in which the first peripheral modified layer M1, the second peripheral modified layer M2, and the divided modified layer M3 have been formed inside the first wafer W, is then transported by the wafer transport device 40 to the peripheral removal device 70.

[0068] In the peripheral edge removal device 70, as shown in FIG. 7(b), removal of the peripheral edge We of the first wafer W, i.e., edge trimming, is performed. At this time, the peripheral edge We is peeled from the center of the first wafer W (the radially inner side of the peripheral edge We) using the first peripheral modified layer M1 as a base point, and is also completely peeled from the second wafer S using the bonding strength reduced region R as a base point. At this time, the removed peripheral edge We is also broken into small pieces using the divided modified layer M3 as a base point. To remove the peripheral edge We, for example, a wedge-shaped blade B (see FIG. 7(b)) may be inserted into the interface between the first wafer W and the second wafer S that form the overlapped wafer T.

[0069] The overlapped wafer T from which the peripheral edge portion We of the first wafer W has been removed is then transferred by the wafer transfer device 40 to the cleaning device 80.

[0070] In the cleaning apparatus 80, the first wafer W and / or the second wafer S after the peripheral edge portion We has been removed is cleaned. In the cleaning apparatus 80, as shown in Fig. 7(c), for example, the first wafer W and the second wafer S may be irradiated with a cleaning laser beam L2 to modify and remove the irradiated portion of the cleaning laser beam L2, thereby removing (cleaning) any remaining particles and the like.

[0071] The peripheral edge We of the first wafer W is removed by the peripheral edge removing device 70, and the overlapped wafer T is cleaned by the cleaning device 80 and then transferred to the grinding device 90. In the grinding device 90, the first wafer W is ground to a target thickness.

[0072] In one embodiment, the overlapped wafer T, in which the first peripheral modified layer M1, the second peripheral modified layer M2, and the divided modified layer M3 have been formed inside the first wafer W by the modifying device 60, is transferred to the grinding device 90 instead of the peripheral removal device 70. In this case, as shown in Fig. 10, the peripheral portion We of the first wafer W is removed in the grinding device 90, and the first wafer W is ground to a target thickness.

[0073] Thereafter, the overlapped wafer T that has undergone all the processing is transferred by the wafer transfer device 20 to the FOUP F on the FOUP mounting table 10 via the transition device 30. In this way, a series of substrate processing steps in the wafer processing system 1 is completed.

[0074] Next, a detailed method for forming the first peripheral modified layer M1 and the second peripheral modified layer M2 in the reformer 60 will be described with reference to the drawings.

[0075] In the modification device 60, first, the overlapped wafer T held by the chuck 100 is moved to a macro imaging position. The macro imaging position is a position where the macro camera 120 can image the outer edge of the first wafer W. At the macro imaging position, while the chuck 100 is being rotated, the macro camera 120 captures images of the outer edge of the first wafer W in a 360-degree circumferential direction (step St1 in FIG. 15: imaging of edge). The captured images are output from the macro camera 120 to the control device 61.

[0076] The control device 61 identifies the position of the notch Wn formed in the first wafer W held by the chuck 100 from the image captured by the macro camera 120, and calculates the amount of eccentricity between the center of rotation of the chuck 100 and the center of the first wafer W. In one example, the amount of eccentricity between the center of rotation of the chuck 100 and the center of the first wafer W is output as a waveform (sine curve) indicating the relationship between the circumferential position of the first wafer W (horizontal axis in the drawing) and the amount of eccentricity (vertical axis in the drawing) as shown in FIG.

[0077] Furthermore, the control device 61 calculates the movement amount of the chuck 100 based on the calculated eccentricity amount so as to correct the Y-axis component of the eccentricity amount. Based on this calculated movement amount, the control device 61 moves the chuck 100 horizontally along the Y-axis direction to move the chuck 100 to a micro-imaging position (step St2: alignment in FIG. 15). The micro-imaging position is a position where the micro-camera 121 can capture an image of the unbonded region Ae of the first wafer W.

[0078] Next, while rotating the chuck 100, the microcamera 121 captures an image of the unbonded region Ae around the notch Wn in at least the portion of the first wafer W where the notch Wn is formed, more specifically, the boundary Ad between the bonded region Ac and the unbonded region Ae (step St3 in FIG. 15: capturing the boundary Ad). In cases where the formation position of the first peripheral modified layer M1 in the portion where the notch Wn is not formed is set in advance, capturing an image of the periphery of the notch Wn makes it possible to set the irradiation position of the second peripheral modified layer M2 in the portion where the notch Wn is formed. In one embodiment, the boundary Ad is captured over 360 degrees in the circumferential direction of the first wafer W. The captured image is output from the microcamera 121 to the control device 61.

[0079] The control device 61 sets the irradiation position of the laser beam L1 for forming the first peripheral modified layer M1 and the second peripheral modified layer M2 based on the image from the macro camera 120 and the image from the micro camera 121 (step St4 in FIG. 15: setting of irradiation position). Specifically, the control device 61 sets the irradiation position of the laser beam L1 as the formation position of the first peripheral modified layer M1 by a preset trim width (a preset distance from the outer edge) based on the position of the outer edge of the first wafer W obtained from the image from the macro camera 120, and also sets the irradiation position of the laser beam L1 as the formation position of the second peripheral modified layer M2 to a bonding region Ac of the first wafer W and the second wafer S radially outward from the irradiation position of the laser beam L1. Furthermore, the control device 61 according to this embodiment takes into account the unbonded region Ae formed corresponding to the notch Wn formed in the peripheral portion We of the first wafer W when setting the irradiation position of the laser beam L1. In other words, in the portion where the notch Wn is not formed, the irradiation position of the laser light as the formation position of the first peripheral modified layer M1 is set with the preset trim width as described above, while in the portion where the notch Wn is formed, the irradiation position of the laser light as the first peripheral modified layer M1 is set so as to avoid the unbonded area Ae corresponding to the notch Wn as described below, and the irradiation position of the laser light L1 as the formation position of the second peripheral modified layer M2 is set in the bonded area Ac corresponding to the notch Wn.

[0080] In the modification device 60, the chuck 100 is moved horizontally to correct the Y-axis component of the eccentricity based on the calculated eccentricity, thereby correcting the eccentricity between the center of rotation of the chuck 100 and the center of the first wafer W, and laser light L1 is irradiated onto the first wafer W along the set irradiation position to form a first peripheral modified layer M1 (step St5 in Figure 15: Formation of first peripheral modified layer M1).

[0081] In conventional edge trimming, the peripheral edge We may be removed with a predetermined trim width without considering the unbonded area Ae formed corresponding to the notch Wn formed in the first wafer W. However, in this case, the unbonded area Ae may remain on the overlapped wafer T after edge trimming, which may cause chipping in subsequent processes.

[0082] Therefore, in the wafer processing according to this embodiment, a first peripheral modified layer M1 that serves as a base point for peeling of the peripheral portion We in the edge trim and a second peripheral modified layer M2 that serves as a base point for the bonding strength reduced region R are formed in consideration of the unbonded region Ae that corresponds to the notch Wn formed in the first wafer W. A detailed method for setting the irradiation position of the laser beam L1 will be described below.

[0083] First, the outer edge position of the first wafer W on the chuck 100 is identified from the image captured by the macro camera 120. Next, the position of the unbonded region Ae formed at a position corresponding to the notch Wn is identified in the 360-degree circumferential direction of the first wafer W. This position is obtained from information previously acquired during an inspection of the bonding of the first wafer W and the second wafer S or empirically determined from past inspection results and stored in the memory of the control device 61, or from the image captured by the micro camera 121. Furthermore, the portion of the unbonded region Ae with the largest radial width (hereinafter referred to as "reference point P": see FIG. 18 ) is identified using the outer edge of the portion where the notch Wn is not formed as a reference. In other words, the reference point P, which is the position of the unbonded region (unbonded region Ae) located at the innermost position in the radial direction of the first wafer W corresponding to the notch Wn, is identified from information previously acquired or information captured by imaging with a camera. In addition, the information acquired in advance during inspection when bonding the first wafer W and the second wafer S may be input into the memory unit of the control device 61 by an operator, or may be input into the memory unit of the control device 61 from an inspection device via a host computer in a factory, etc.

[0084] Next, in at least a portion of the semi-circumferential region on the side where the notch Wn is not formed (for example, within a range of ±90 degrees circumferentially from the position opposite the position where the notch Wn is formed), a first peripheral modified layer M1 is formed so as to overlap the boundary Ad between the unbonded region Ae and the bonded region Ac, and in the semi-circumferential region on the side where the notch Wn is formed in the circumferential direction of the first wafer W (for example, within a range of ±90 degrees circumferentially from the notch Wn), the first peripheral modified layer M1 is formed into an elliptical shape in a planar view.

[0085] More specifically, first, the irradiation position of the laser beam L1 (the formation position of the first peripheral modified layer M1) is set so as to overlap with the boundary Ad in at least a part of the semicircular region on the side where the notch Wn is not formed in the circumferential direction of the first wafer W (in the example of FIG. 17, the range from θ(90) to θ(270) clockwise, with the notch Wn as the reference θ(0)) (step St4 in FIG. 15). At this time, the first peripheral modified layer M1 formed so as to overlap with the boundary Ad is concentric with the first wafer W, and its radius r1 is equal to the diameter of the boundary Ad when the boundary Ad is considered to be a circle (see FIG. 17).

[0086] Next, in at least a portion of the semicircular region of the first wafer W on the side where the notch Wn is formed in the circumferential direction (the range from θ(90) to θ(270) counterclockwise in the example of FIG. 17), the irradiation position of the laser beam L1 (the formation position of the first peripheral modified layer M1) is set in an elliptical shape having a minor axis extending from the center of the first wafer W toward the formation position of the notch Wn (step St4 in FIG. 15). At this time, the major axis r2 of the elliptical formed first peripheral modified layer M1 is set to coincide with the above-mentioned diameter r1, and the minor axis r3 of the first peripheral modified layer M1 is set to be smaller than the above-mentioned diameter r1 in consideration of the notch Wn (see FIG. 17). More specifically, the irradiation position of the laser beam L1 is set so that the reference point P coincides with the formation position of the first peripheral modified layer M1 or is located radially outward of the formation position of the first peripheral modified layer M1. Hereinafter, the formation position of the elliptical shape will be referred to as the "formed ellipse."

[0087] Following this, the radially outer bonding area Ac or unbonded area Ae of the formation ellipse of the first peripheral modified layer M1 in the semicircular region on the formation side of the notch Wn is set as the irradiation position of the laser light L1 (the formation position of the second peripheral modified layer M2).

[0088] More specifically, as shown in FIG. 18, the second peripheral modified layer M2 is formed by one or more ellipses (in this embodiment, multiple ellipses) that are concentric with the first peripheral modified layer M1's forming ellipse in the semicircular region on the side where the notch Wn is formed. The major and minor axes are larger than the major and minor axes r2 and r3 of the first peripheral modified layer M1's forming ellipse and have a ratio equal to the r2:r3 ratio. In other words, the second peripheral modified layer M2 in the semicircular region on the side where the notch Wn is formed is formed by one or multiple forming ellipses. The minor axis of the multiple forming ellipses of the second peripheral modified layer M2 is at most φ. The maximum minor axis φ of the second peripheral modified layer M2's forming ellipse can be set, for example, as the sum (r3 + d) of the minor axis r3 and the distance d from the boundary Ad to the first peripheral modified layer M1's forming ellipse. In addition, the major axis of the formed ellipse of the second peripheral modified layer M2 can be set based on the ratio r2:r3 of the major axis to the minor axis of the formed ellipse of the first peripheral modified layer M1.

[0089] The diameters of the ellipses of the multiple second peripheral modified layers M2 are set so that the second peripheral modified layers M2 are formed with a radial spacing of P. For example, the minor axis of the ellipses of the innermost second peripheral modified layer M2 is set to (r3 + P), and the minor axis increases by P from there to the maximum minor axis φ. The number of ellipses of the second peripheral modified layer M2 is set to the maximum number that can be formed with the minor axis set as described above, for example.

[0090] The second peripheral modified layer M2 is formed in the bonded region Ac or unbonded region Ae radially outward of the formation ellipse of the first peripheral modified layer M1 in the semicircular region on the side where the notch Wn is formed. As an example, the second peripheral modified layer M2 is formed in the unbonded region Ae surrounded by the first peripheral modified layer M1 and the boundary Ad. Note that, as shown in FIG. 18, the second peripheral modified layer M2 may also be formed in the semicircular region on the side where the notch Wn is not formed. In this case, in the semicircular region on the side where the notch Wn is not formed, the formation circle of the second peripheral modified layer M2 is set to be concentric with the formation circle of the first peripheral modified layer M1 and have a diameter larger than the diameter r1.

[0091] The region that distinguishes between the side where the notch Wn is formed and the side where it is not formed is not limited to the semicircular region bounded by θ(90) and θ(270) as shown in Fig. 17. For example, the region on the side where the notch Wn is not formed, to which the laser beam L1 is irradiated concentrically with the first wafer W, may be set as a sector-shaped region with a central angle greater than or less than 180 degrees, and the laser beam L1 may be irradiated concentrically with the first wafer W in this sector-shaped region. In this case, the larger the central angle of the sector-shaped region to which the laser beam L1 is irradiated concentrically with the first wafer W, the smaller the amount of removal of the peripheral edge portion We of the first wafer W can be.

[0092] In one embodiment, as shown in Figures 20 and 21, the region on the side where the notch Wn is not formed is set so that the central angle is greater than 180 degrees. In this case, the irradiation shape of the laser light L1 on the first peripheral modified layer M1 on the side where the notch Wn is formed may be set to a substantially elliptical shape as shown in Figure 20, or may be set to a straight line (so-called orientation flat shape) with a chord connecting the two endpoints of the irradiation position of the first peripheral modified layer M1 on the side where the notch Wn is not formed, as shown in Figure 21. In this case, the second peripheral modified layer M2 may be formed as a circle concentric with the forming circle of the first peripheral modified layer M1, as a concentric ellipse with the forming ellipse, or as parallel lines.

[0093] In the modification device 60, the chuck 100 is moved horizontally so as to cancel out the sine curve component of the waveform shown in Figure 16, and laser light L1 is irradiated along the set irradiation position to form a first peripheral modification layer M1 (step St5 in Figure 15).

[0094] In the modification device 60, laser light L1 is applied to the inside of the first wafer W in the bonded region Ac or the unbonded region Ae radially outward from the formation position of the first peripheral modified layer M1 in the semicircular region on the notch Wn side, to form the second peripheral modified layer M2 (step St6 in FIG. 15: see FIG. 18). Preferably, the second peripheral modified layer M2 is formed radially from the outer side to the inner side, that is, from the larger formed ellipse to the smaller formed ellipse. This allows the tensile stress generated in the stress concentration regions Q1 and Q2 to be more efficiently converted into compressive stress that warps the upper portion of the first wafer W obliquely upward.

[0095] According to this embodiment, in the circumferential direction of the first wafer W, on the side where the notch Wn is not formed, the first peripheral modified layer M1 is formed so that it overlaps with the boundary Ad, thereby narrowing the trim width and improving yield, while on the side where the notch Wn is formed, the first peripheral modified layer M1 is formed in an elliptical shape, thereby suppressing the occurrence of chipping in subsequent processes.

[0096] At this time, the first peripheral modified layer M1 is formed while moving the chuck 100 horizontally to correct the eccentricity of the center of the first wafer W relative to the rotation center of the chuck 100, thereby appropriately preventing the first peripheral modified layer M1 from being formed in the unbonded area Ae.

[0097] Furthermore, in the bonding region Ac radially outward from the formation position of the first peripheral modification layer M1 in the semi-circumferential region on the formation side of the notch Wn, by forming a second peripheral modification layer M2, a bonding strength reduction region R can be formed in the bonding region Ac between the formation circle of the first peripheral modification layer M1 and the boundary Ad.

[0098] In this embodiment, the second peripheral modified layer M2 is formed to form an ellipse concentric with the formation ellipse of the first peripheral modified layer M1, but this is not limited to this. For example, as a modification of this embodiment, if the slider table 102 is configured to be movable in the X-axis direction as well as the Y-axis direction, the second peripheral modified layer M2 is formed using multiple straight formation lines. Specifically, as shown by the dotted lines in FIG. 19 , the formation position of the second peripheral modified layer M2 is set so that multiple formation lines are parallel lines with a line width spaced apart by P in the bonded region Ac or unbonded region Ae radially outward from the formation position of the first peripheral modified layer M1. Each of the parallel formation lines is a straight line connecting two points on an arc of the boundary Ad in the semicircular region on the notch Wn side. In this embodiment, the parallel line of the formation position of the second peripheral modified layer M2 is a straight line parallel to the major axis r2 of the formation ellipse of the first peripheral modified layer M1 in the semicircular region on the notch Wn side. The number of parallel lines is set to the maximum number that can be formed with a spacing P between the boundary Ad and the formed ellipse of the first peripheral modified layer M1, for example.

[0099] The second peripheral modified layer M2 may be formed in the shape of concentric circles or a spiral, in addition to concentric ellipses or parallel lines. The order in which the first peripheral modified layer M1 and the second peripheral modified layer M2 are formed does not matter.

[0100] Here, the formation of the first peripheral modified layer M1 concentric with the first wafer W in the non-notch Wn portion and the formation of the first peripheral modified layer M1 in each of the above-mentioned shapes in the notch Wn portion may be carried out continuously in a so-called one-stroke manner, or may be carried out independently in two separate steps.

[0101] (When forming the first peripheral modification layer M1 continuously) When forming the first peripheral modified layer M1 on the portion where the notch Wn is not formed and forming the first peripheral modified layer M1 on the portion where the notch Wn is formed successively, for example, as shown in Fig. 22, the irradiation shape of the laser beam L1 set for the portion where the notch Wn is to be formed (in the example shown in Fig. 22, the elliptical shape corresponding to Fig. 20) is superimposed on the waveform (see Fig. 16) created to correct the eccentricity between the center of rotation of the chuck 100 and the center of the first wafer W, in accordance with the circumferential position (angle) of the notch Wn, to generate a composite waveform as shown in Fig. 22. Then, the first peripheral modified layer M1 is formed inside the first wafer W using the composite waveform created in this way.

[0102] Specifically, in the portion where the notch Wn is not formed, the chuck 100 is rotated around the vertical axis, and the chuck 100 is moved horizontally (to correct the eccentricity) so as to cancel out the sine curve component of the composite waveform (the eccentricity between the center of rotation of the chuck 100 and the center of the first wafer W), and the laser light L1 is irradiated concentrically with the first wafer W.

[0103] Furthermore, in the portion where the notch Wn is to be formed, the laser beam L1 is irradiated while the chuck 100 and the laser head 110 are moved relatively in the horizontal direction so as to avoid the unbonded region Ae in the portion where the notch Wn is to be formed, more specifically so that the identified reference point P is positioned radially outward from the irradiation position of the laser beam L1. At this time, the chuck 100 may be rotated around the vertical axis in accordance with the irradiation shape of the laser beam L1, or the rotation may be stopped.

[0104] (When forming the first peripheral modification layer M1 in two steps) On the other hand, when the formation of the first peripheral modified layer M1 on the non-formed portion of the notch Wn and the formation of the first peripheral modified layer M1 on the formed portion are carried out in two separate steps, first, a composite waveform (see Figure 22) is generated by superimposing the set irradiation shape of the laser light L1, as in the case of continuously forming the first peripheral modified layer M1.

[0105] Next, while rotating the chuck 100 around the vertical axis, the chuck 100 is moved horizontally (to correct the eccentricity) so as to cancel out the sine curve component of the composite waveform (the eccentricity between the center of rotation of the chuck 100 and the center of the first wafer W) and irradiate the laser light L1 concentrically with the first wafer W with respect to the non-forming portion of the notch Wn.

[0106] After the first peripheral modified layer M1 is formed in the portion where the notch Wn is not formed, the chuck 100 is then moved to a position where the first peripheral modified layer M1 will be formed in the portion where the notch Wn will be formed. As shown in FIGS. 23 and 24 , the irradiation shape of the laser beam L1 for generating the composite waveform can be generated, for example, by superimposing a circular or elliptical shape having a rotation axis different from that of the first wafer W. From this perspective, when forming the first peripheral modified layer M1 in the portion where the notch Wn will be formed, the chuck 100 (first wafer W) is moved so that the rotation center of the chuck 100 coincides with the rotation axis of the circular or elliptical shape superimposed to generate the composite waveform. Then, the chuck 100 is rotated about the vertical axis at the position where the first peripheral modified layer M1 will be formed in the portion where the notch Wn will be formed, and the laser beam L1 is irradiated into the interior of the first wafer W.

[0107] 21, the irradiation shape of the laser beam L1 does not have a rotation axis as shown in FIGS. 23 and 24. In such a case, it is not necessary to move the chuck 100 to a position for forming the first peripheral modified layer M1 in the portion where the notch Wn is to be formed. The laser beam L1 may be irradiated onto the interior of the first wafer W simply by moving the chuck 100 and the laser head 110 relatively in the horizontal direction. Specifically, in one embodiment, if the slider table 102 is configured to be movable in the X-axis direction, the laser beam L1 is irradiated onto the interior of the first wafer W by moving the slider table 102 in the X-axis direction.

[0108] In the above embodiment, information on the unbonded portion (the formation position of the unbonded portion where the first wafer W and the second wafer S are not bonded), including the formation position of the unbonded region Ae in the peripheral edge portion We (more specifically, the position of the boundary Ad), may be acquired from the image capture results using a camera, for example, or information obtained in advance outside the wafer processing system 1 may be output to the control device 61 at the same time as the overlapped wafer T (FOUP F) is carried into the wafer processing system 1. This information on the unbonded portion can be acquired, for example, by a bonding device (not shown) that bonds the first wafer W and the second wafer S.

[0109] Furthermore, in the above embodiment, the information on the unbonded portion is obtained from the image captured by the camera in the modifying device 60, but the information may be obtained by capturing an image by placing a camera in another device in the wafer processing system 1. The camera capturing an image of the first wafer W may be located, for example, in the transition device 30.

[0110] Furthermore, in the above embodiment, the position of the boundary Ad between the unbonded area Ae and the bonded area Ac obtained from the image capture results by the camera was used as the "information on the unbonded portion" mentioned above. However, as mentioned above, the unbonded portion of the first wafer W and the second wafer S can also occur radially inward of the boundary Ad.

[0111] In view of this, it is desirable that the "information on the unbonded portion" acquired prior to the formation of the first peripheral modified layer M1 includes the position of the unbonded portion located radially innermost at the interface between the first wafer W and the second wafer S in the portion where the notch Wn is to be formed. In this case, the unbonded portion located radially innermost at the interface between the first wafer W and the second wafer S becomes the "reference point P."

[0112] 25, the first wafer W on which the first peripheral modified layer M1 is formed in the wafer processing system 1 according to the technology of the present disclosure has a first crystal orientation CO1 and a second crystal orientation CO2 alternately arranged in the circumferential direction of the first wafer W. A notch Wn formed in the first wafer W indicates this crystal orientation.

[0113] Therefore, in order to properly extend the crack C along the crystal orientation from the first peripheral modified layer M1 formed on the first wafer W in the modification device 60, it is necessary to take this crystal orientation into consideration when setting irradiation conditions such as the incident direction of the laser light L1 and the focal point shape of the laser light L1 (longitudinal direction of the focal point).

[0114] Specifically, when the first peripheral modified layer M1 is formed concentrically with the first wafer W, the irradiation conditions of the laser light L1 are changed according to the crystal orientation (first crystal orientation CO1 or second crystal orientation CO2) shown in FIG.

[0115] 20 and 21, when the first peripheral modified layer M1 is formed while avoiding the notch Wn, the relative irradiation angle of the laser beam L1 with respect to the crystal orientation of the first wafer W changes depending on the irradiation shape of the laser beam L1 in a planar view (the irradiation position of the laser beam L1). Therefore, in the portion where the notch Wn is formed, the irradiation conditions of the laser beam L1 are changed taking into consideration not only the crystal orientation (first crystal orientation CO1 or second crystal orientation CO2) shown in FIG. 25 but also the trim shape of the peripheral portion We (the irradiation shape of the laser beam L1 in a planar view).

[0116] The information about the crystal orientation of the first wafer W may be acquired, for example, simultaneously with the loading of the overlapped wafer T (FOUP F) into the wafer processing system 1 or prior to this.

[0117] In the above explanation, as shown in Figure 7, the first peripheral modified layer M1, the second peripheral modified layer M2, and the divided modified layer M3 are formed using the modification device 60. In addition to this, an interface modification device (not shown) may be provided, in which the bonding portion at the interface between the first wafer W and the second wafer S remaining in the peripheral portion We is irradiated with laser light in the interface modification device to modify it, thereby further reducing the bonding strength in the bonding strength reduction region R.

[0118] In the above embodiment, the unbonded region Ae is formed on the overlapped wafer T, which is formed by bonding the first wafer W and the second wafer S. However, the unbonded region Ae may be formed on the first wafer W or the second wafer S before the first wafer W and the second wafer S are bonded, and then the first wafer W and the second wafer S may be bonded to form the overlapped wafer. In this case, the unbonded region Ae may be formed by a laser process or an etching process such as wet etching. Alternatively, the unbonded region Ae may be formed on the overlapped wafer T by a laser process or the like after the first wafer W and the second wafer S are bonded.

[0119] Furthermore, in the above embodiment, if an unbonded area Ae is formed within the first wafer W closer to the inner periphery of the wafer than the unbonded area in the notch Wn, the formation position of the first peripheral modified layer M1 may be set based on information about the unbonded portion described above, in accordance with the innermost unbonded area Ae.

[0120] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. For example, the components of the above-described embodiments may be arbitrarily combined. Such an arbitrary combination naturally provides the functions and effects of each of the components involved in the combination, and also provides other functions and effects that are apparent to those skilled in the art from the description of this specification.

[0121] 26, in a cross-sectional view, on the back surface Wb of the first wafer W, the first peripheral modified layer M1 is formed at a position closer to the center of the wafer than the boundary Ad between the unbonded region Ae and the bonded region Ac. Furthermore, near the bonding surface between the first wafer W and the second wafer S, the first peripheral modified layer M1 is formed at a position closer to the boundary Ad. As a result, cracks C are formed obliquely toward the boundary Ad from a midpoint in the thickness direction of the first wafer W to the bonding surface between the first wafer W and the second wafer S.

[0122] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that would be apparent to a person skilled in the art from the description of this specification, in addition to or in place of the above-described effects. [Explanation of symbols]

[0123] 1. Wafer Processing System Ac junction area Ae Unbonded area L1 laser light M1 First peripheral modification layer M2 Second peripheral modification layer S Second wafer T Polymerized Wafer W First wafer Wc central part We Periphery Wn notch

Claims

1. A substrate processing method for processing a laminated substrate in which a first substrate and a second substrate are bonded together, comprising: The first substrate is a notch formed by cutting out a part of a peripheral edge portion of the first substrate to be removed; a bonding portion bonded to the second substrate; an unbonded portion that is not bonded to the second substrate, irradiating a laser beam along a boundary between the peripheral portion of the first substrate and a central portion of the first substrate to form a first peripheral modified layer that serves as a base point for peeling off the peripheral portion; and irradiating a laser beam radially outward from the first peripheral modified layer to form a second peripheral modified layer that serves as a base point for a bonding strength reduction region that reduces the bonding strength at the bonding portion. When forming the first peripheral modification layer, A substrate processing method comprising: setting formation positions of the first peripheral modified layer and the second peripheral modified layer corresponding to a portion where the notch is to be formed based on information about the unbonded portion.

2. 2. The substrate processing method of claim 1, wherein when forming the second peripheral modified layer, at least the spacing or intensity of the laser light is controlled, and the second peripheral modified layer is formed so that cracks extending from each of the second peripheral modified layers do not connect adjacent second peripheral modified layers.

3. forming the first peripheral modified layer concentrically with the first substrate in a plan view in at least a part of a semi-circumferential region on a side of the first substrate where the notch is not formed; forming the first peripheral modified layer in an elliptical shape having a minor axis extending from the center of the first substrate toward the position where the notch is formed in at least a part of a semi-circumferential region on the side where the notch is formed in the first substrate in a plan view; 2. The substrate processing method of claim 1, further comprising: forming the second peripheral modification layer outside the first peripheral modification layer, the first peripheral modification layer being formed in an elliptical shape having a minor axis extending from the center of the first substrate toward the position where the notch is formed.

4. the information on the unbonded portion includes a position of a reference point in the unbonded portion that is located at the innermost position in a radial direction of the first substrate in a portion where the notch is formed, a major axis of the elliptical shape is set to be the same length as a diameter of the concentric circle in a semicircular region on the side where the notch is not formed, The substrate processing method according to claim 3 , wherein a minor axis of the elliptical shape is set to be smaller than a distance from a center of the first substrate to the reference point.

5. 4. The substrate processing method of claim 3, wherein the second peripheral modification layer is formed by one or more forming ellipses that are concentric ellipses with the first peripheral modification layer that is formed in the elliptical shape in a planar view in at least a portion of the semicircular region on the side where the notch is formed in the first substrate.

6. the information on the unbonded portion includes a position of a reference point in the unbonded portion that is located at the innermost position in a radial direction of the first substrate in a portion where the notch is formed, forming the first peripheral modified layer concentrically with the first substrate in a plan view in a portion of the first substrate in a circumferential direction where the notch is not formed; forming the first peripheral modified layer in a shape that follows the unbonded portion formed in a plan view corresponding to the notch in a portion of the first substrate where the notch is formed in a circumferential direction; 2. The substrate processing method of claim 1, further comprising: forming the second peripheral modification layer outside the first peripheral modification layer, which is formed in a shape that follows the unbonded portion formed in correspondence with the notch.

7. The substrate processing method according to claim 6 , wherein the second peripheral modified layer is formed by a plurality of formation lines that are parallel to each other in a plan view in at least a part of the portion of the first substrate where the notch is formed.

8. The first peripheral modified layer is formed by a straight line in a portion of the first substrate where the notch is formed in the circumferential direction, The substrate processing method according to claim 6 , wherein the second peripheral modified layer is formed by a plurality of formation lines parallel to the straight formation line.

9. generating a composite waveform indicating the formation position of the first peripheral modified layer relative to the first substrate by superimposing a waveform indicating the correlation between the eccentricity amount between the center of the first substrate in the circumferential direction of the first substrate and the rotation center of a substrate holding part that holds the overlapped substrate and a formation shape of the first peripheral modified layer in a planar view relative to the formation portion of the notch; 9. The substrate processing method according to claim 6, further comprising: performing averaging processing on the generated composite waveform.

10. 9. The substrate processing method according to claim 6, further comprising: setting irradiation conditions for the laser light on the first substrate in consideration of a crystal orientation of the first substrate and a formation shape of the first peripheral modification layer in a planar view relative to the notch formation portion.

11. 9. The substrate processing method according to claim 1, further comprising: acquiring information about the unbonded portion by imaging the laminated substrates held by a substrate holder.

12. irradiating a laser beam to a radially outer side of the first peripheral modified layer to form a divided modified layer that serves as a starting point for dividing the peripheral portion into small pieces; A substrate processing method described in any one of claims 1 to 8, wherein the divided modification layer includes a first spiral formation portion formed concentrically with the first substrate, and a second spiral formation portion formed concentrically with the first substrate and in the opposite direction to the first spiral formation portion.

13. irradiating a laser beam to a radially outer side of the first peripheral modified layer to form a divided modified layer that serves as a starting point for dividing the peripheral portion into small pieces; A substrate processing method described in any one of claims 1 to 8, wherein the divided modification layer includes a first spiral formation portion formed concentrically with the first substrate, and a second spiral formation portion concentric with the first substrate and having a different number of turns than the first spiral formation portion.

14. A substrate processing system for processing a laminated substrate in which a first substrate and a second substrate are bonded together, The first substrate is a notch formed by cutting out a part of a peripheral edge portion of the first substrate to be removed; a bonding portion bonded to the second substrate; an unbonded portion that is not bonded to the second substrate, a modification device that irradiates a laser beam along the boundary between the peripheral edge portion of the first substrate and a central portion of the first substrate to form a first peripheral modified layer that serves as a base point for peeling of the peripheral edge portion, and that irradiates a laser beam radially outward from the first peripheral modified layer to form a second peripheral modified layer that serves as a base point for a stress concentration region that reduces the bonding strength at the bonding portion; a peripheral edge removing device that peels off the peripheral portion from the laminated substrate using the first peripheral modified layer as a base point; a control device; The control device A substrate processing system that, when forming the first peripheral modified layer, performs control to set the formation positions of the first peripheral modified layer and the second peripheral modified layer corresponding to the formation portion of the notch based on information about the unbonded portion.

15. The reformer is a substrate holder for holding the laminated substrate; a laser irradiation unit that irradiates the laser light; a camera that captures an image of the laminated substrate held by the substrate holder, The control device The substrate processing system according to claim 14 , wherein the operation of the modifying device is controlled so as to acquire information about the unbonded portion by imaging the laminated substrate held by the substrate holding unit.

16. The control device 15. The substrate processing system of claim 14, wherein when forming the second peripheral modified layer, at least the spacing or intensity of the laser light is controlled so that cracks extending from each of the second peripheral modified layers do not connect adjacent second peripheral modified layers.

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