Substrate processing system and substrate processing method

Abstract

According to the present invention, a control unit executes: control for forming a first modified region including a first modified part modified by laser irradiation at a plurality of points arranged in the thickness direction of a first substrate along or radially outside an inner periphery of a peripheral edge part of an area to be removed on the first substrate and a first crack extending from the first modified part; control for preventing the first crack from reaching the back surface on the side of the first substrate opposite the second substrate; control for forming a second modified region including a second modified part modified by laser irradiation at a plurality of points arranged in the thickness direction of the first substrate radially inside the first modified region and a second crack extending from the second modified part; and control for causing the second crack to reach the back surface of the first substrate and to connect to the first modified region.

Description

Substrate processing system and substrate processing method

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

[0002] Each of Patent Documents 1 to 3 discloses a substrate processing system for processing a laminated substrate formed by bonding a first substrate and a second substrate. The substrate processing system includes a modified layer forming device for forming a modified layer inside the first substrate, an interface processing device for modifying the interface where the first substrate and the second substrate are bonded, and an edge removing device for removing the edge portion of the first substrate.

[0003] International Publication No. 2019 / 176589 International Publication No. 2019 / 208298 International Publication No. 2019 / 208359

[0004] The technology according to the present disclosure appropriately removes the peripheral edge portion of the first substrate to be removed in a laminated substrate in which a first substrate and a second substrate are bonded together.

[0005] One aspect of the present disclosure is a substrate processing system for processing a laminated substrate in which a first substrate and a second substrate are bonded together, the system including: a laser irradiation unit that irradiates laser light; and a control unit. The control unit performs the following operations: control to form a first modified region, the first modified region including a first crack extending from the first modified region, modified by irradiating a plurality of points aligned in the thickness direction of the first substrate with a laser, radially outward from the inner periphery of a peripheral portion of the first substrate or along the peripheral portion; control to prevent the first crack from reaching the back surface of the first substrate opposite the second substrate; control to form a second modified region, the second modified region including a second crack extending from the second modified region, modified by irradiating a plurality of points aligned in the thickness direction of the first substrate with a laser, radially inward from the first modified region; and control to allow the second crack to reach the back surface of the first substrate and connect to the first modified region.

[0006] According to the present disclosure, in a laminated substrate in which a first substrate and a second substrate are bonded together, the peripheral edge portion of the first substrate to be removed can be appropriately removed.

[0007] FIG. 1 is an explanatory diagram of overlapping wafers to be processed. FIG. 2 is a plan view showing an outline of the configuration of a wafer processing system. FIG. 3 is a side view showing an outline of the configuration of a first laser irradiation device. FIG. 4 is a plan view showing an outline of the configuration of a first laser irradiation device. FIG. 5 is an explanatory diagram showing main steps of wafer processing according to the first embodiment. FIG. 6 is an explanatory diagram showing main steps of wafer processing according to the second embodiment. FIG. 7 is an explanatory diagram showing main steps of wafer processing according to the third embodiment. FIG. 8 is an explanatory diagram showing main steps of wafer processing according to the fourth embodiment. FIG. 9 is an explanatory diagram showing main steps of wafer processing according to the fifth embodiment. FIG. 10 is an explanatory diagram showing how the first wafer is irradiated with the first laser light in the present embodiment. FIG. 11 is an explanatory diagram showing how the first wafer is irradiated with the first laser light in a comparative example.

[0008] Hereinafter, a wafer processing system as a substrate processing system and a wafer processing method as a substrate processing method according to the present embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0009] 1 , a wafer processing system 1 according to this embodiment, which will be described later, processes an overlapped wafer T as an overlapped substrate in which a first wafer W as a first substrate and a second wafer S as a second substrate are bonded together. 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.

[0010] The first wafer W is a semiconductor wafer such as a silicon substrate, and at least one film is laminated on the surface Wa. Hereinafter, the film formed on the surface Wa will be referred to as a "laminated film." In this embodiment, the laminated film includes a device layer Dw and a bonding film Fw. The device layer Dw includes multiple devices. The device layer Dw may also include a layer (laser absorption layer) that absorbs the third laser light (described later) and serves as a base point for delamination. 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. The first wafer W is then bonded to the second wafer S via the bonding film Fw. The peripheral edge We of the first wafer W is chamfered, and the cross-section of the peripheral edge We tapers toward its tip. In the following description, the region of the first wafer W radially inward of the peripheral edge We to be removed may be referred to as a central region We.

[0011] The second wafer S has, for example, the same configuration as the first wafer W. That is, a device layer Ds and a bonding film Fs are formed as laminated films on the surface Sa side, and the peripheral portion is chamfered. 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. In such a case, the second wafer S functions as a protective material that protects the device layer Dw of the first wafer W.

[0012] 1 illustrates an example in which a device layer and a bonding film are formed as laminated films on the surfaces of the first wafer W and the second wafer S. However, the type and number of laminated films are not limited to this.

[0013] 2 , 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.

[0014] The carry-in / out station 2 is provided with a FOUP mounting table 10 on which a plurality of FOUPs F, for example, three FOUPs F, can be placed. A wafer transfer device 20 is provided 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 wafer T between the FOUP F on the FOUP mounting table 10 and a transition stage 30, which will be described later.

[0015] A transition stage 30 is provided in the transfer station 2 on the X-axis positive side of the wafer transfer device 20. The transition stage 30 temporarily stores the overlapped wafer T for transfer to and from the processing station 3.

[0016] The processing station 3 is provided with a wafer transfer device 40, a first laser irradiation device 50, a second laser irradiation device 60, an edge removal device 70, and a cleaning device 80. The wafer transfer device 40 is disposed on the X-axis positive side of the transition stage 30. The first laser irradiation device 50 and the second laser irradiation device 60 are disposed on the Y-axis positive side of the wafer transfer device 40, and the edge removal device 70 and the cleaning device 80 are disposed on the Y-axis negative side of the wafer transfer device 40. The number and arrangement of the first laser irradiation device 50, the second laser irradiation device 60, the edge removal device 70, and the cleaning device 80 are not limited to those in this embodiment and can be determined as desired.

[0017] The wafer transport device 40 is configured to be freely movable on a transport path 41 extending in the X-axis direction, and is configured to be able to transport the overlapped wafer T to the transition stage 30, the first laser irradiation device 50, the second laser irradiation device 60, the edge removal device 70, and the cleaning device 80.

[0018] 5, the first laser irradiation device 50 irradiates the inside of the first wafer W with a first laser beam L1 (modifying laser beam, for example, a YAG laser or a fiber laser) to form a first modified region M1, a second modified region M2, and a third modified region M3, and thereby forms a first modified region N1, a second modified region N2, and a third modified region N3. Also, as shown in FIG. 2, the first laser irradiation device 50 has a control device 51, which will be described later.

[0019] 3 and 4, the first laser irradiation device 50 has a chuck 100 that holds the overlapped wafer T on its upper surface. With the first wafer W on top and the second wafer S on the bottom, the chuck 100 suction-holds the back surface Sb of the second wafer S. The chuck 100 is provided with lifting pins (not shown) for supporting and lifting the overlapped wafer T from below. The lifting pins are inserted into through-holes (not shown) formed through the chuck 100 and are configured to be freely raised and lowered.

[0020] The chuck 100 is supported by a slider table 102 via an air bearing 101. A rotation mechanism (rotor) 103 is provided on the underside 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 via the air bearing 101 by the rotation mechanism 103. The slider table 102 is configured to be movable along rails 106 extending in the Y-axis direction on a base 105 via a movement mechanism (transporter) 104 provided on the underside of the slider table 102. The drive source of the movement mechanism 104 is not particularly limited, but a linear motor, for example, is used.

[0021] A laser irradiation unit 110 is provided above the chuck 100. The laser irradiation unit 110 includes a laser head 111, an optical system 112, and a lens 113.

[0022] The laser head 111 has a laser oscillator (not shown) that oscillates the first laser light L1 in a pulsed manner. This first laser light L1 is a so-called pulse laser. As described above, the first laser light L1 is, for example, a YAG laser or a fiber laser. Note that the laser head 111 may also have other devices in addition to the laser oscillator, such as an amplifier.

[0023] The optical system 112 may include an optical element (not shown) that controls the intensity and position of the first laser light L1, and an attenuator (not shown) that attenuates the first laser light L1 to adjust the output. The optical system 112 may also be configured to be able to control the number and shape of the branches of the first laser light L1.

[0024] The lens 113 irradiates the first laser light L1 onto the inside of the first wafer W held by the chuck 100. As a result, the portion inside the laminated wafer T irradiated with the first laser light L1 is modified to form a first modified region M1, a second modified region M2, and a third modified region M3, as shown in Fig. 5. The lens 113 is configured to be able to be raised and lowered in the vertical direction by an elevating mechanism (actuator) 114. The configuration of the elevating mechanism 114 is arbitrary, and may be, for example, a motor-driven ball screw or a piezoelectric element.

[0025] An imaging unit 120 is provided above the chuck 100 on the positive Y-axis side of the lens 113. The imaging unit 120 includes at least one camera. An image captured by the camera is output to a control device 51 or a control device 90, which will be described later. The first laser irradiation device 50 determines the position of the overlapped wafer T on the chuck 100 based on the image obtained by the imaging unit 120, and aligns the overlapped wafer T based on this.

[0026] 5, the second laser irradiation device 60 irradiates an irradiation target with second laser light L2 (removal laser light, for example, a UV femtosecond laser) and removes the irradiation target by laser ablation. As will be described later, the irradiation target is, for example, a surface film (bonding films Fw, Fs and device layers Dw, Ds) on the surface Sa of the second wafer S. Also, as shown in FIG. 2, the second laser irradiation device 60 has a control device 61, which will be described later.

[0027] The configuration of the second laser irradiation device 60 is not particularly limited, but in one example, the second laser irradiation device 60 has the same configuration as the first laser irradiation device 50 .

[0028] As shown in FIG. 5 , the edge removal device 70 removes the edge portion We of the first wafer W, i.e., performs edge trimming, using the first modified region N1, the second modified region N2, and the peeled region P as base points. Any edge trimming method can be selected. In one example, the edge removal device 70 may insert, for example, a wedge-shaped blade B as an edge remover. Alternatively, for example, an impact may be applied to the edge portion We by spraying air or a water jet toward the edge portion We, or by applying a member to the edge portion We from the rear surface of the first wafer W. Furthermore, for example, an adhesive tape may be attached to the rear surface of the first wafer W and the adhesive tape may be expanded.

[0029] The cleaning device 80 performs a cleaning process on the first wafer W and the second wafer S after the edge trimming by the edge removal device 70, thereby removing particles from these wafers. Any cleaning method can be selected.

[0030] 2 , the wafer processing system 1 described above is provided with a control unit including a control device 51, a control device 61, and at least one control device 90. The control device 51 individually controls the operation of the first laser irradiation device 50. The control device 61 individually controls the operation of the second laser irradiation device 60. The control device 90 comprehensively controls a series of wafer processing operations in the wafer processing system 1.

[0031] The control devices 51, 61, and 90 each process computer-executable instructions that cause the first laser irradiation device 50, the second laser irradiation device 60, and the wafer processing system 1 to perform the various steps described in this disclosure. The control devices 51, 61, and 90 can each be configured to control each element of the first laser irradiation device 50, the second laser irradiation device 60, and the wafer processing system 1 to perform the various steps described herein. In one embodiment, some or all of the control device 51 may be included in the first laser irradiation device 50, some or all of the control device 61 may be included in the second laser irradiation device 60, and some or all of the control device 90 may be included in the wafer processing system 1.

[0032] The control devices 51, 61, and 90 may each include a processing unit, a storage unit, and a communication interface. The control devices 51, 61, and 90 may each be realized by, for example, a computer. The processing unit may be configured to read a program providing logic or routines that enable various control operations from the storage unit and execute the read program to perform various control operations. This program may be stored in the storage unit in advance 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 CPU (Central Processing Unit) or one or more circuits. The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination thereof. The communication interface may communicate between the first laser irradiation device 50, the second laser irradiation device 60, and the wafer processing system 1 via a communication line such as a LAN (Local Area Network).

[0033] In this embodiment, the control device 51 and the control device 61 are installed separately for the first laser irradiation device 50 and the second laser irradiation device 60, respectively, but these control devices 51 and 61 may be configured integrally with the control device 90. In other words, the operations of the first laser irradiation device 50 and the second laser irradiation device 60 may be controlled by the control device 90.

[0034] Next, a description will be given of wafer processing according to the first embodiment, which is performed using the wafer processing system 1 configured as described above. In this embodiment, the first wafer W and the second wafer S are bonded together to form an overlapped wafer T in advance.

[0035] First, a FOUP F containing a plurality of overlapping wafers T is placed on the FOUP placement table 10 of the carry-in / out station 2 .

[0036] Next, the overlapped wafer T is removed from the FOUP F by the wafer transfer device 20 and transferred to the transition stage 30. Subsequently, the overlapped wafer T is transferred to the first laser irradiation device 50 by the wafer transfer device 40.

[0037] In the first laser irradiation device 50, as shown in Figures 5(a) to (c), a first laser light L1 is irradiated into the inside of the first wafer W to form a first modified region N1, a second modified region N2, and a third modified region N3.

[0038] First, as shown in FIG. 5A, the first laser light L1 is irradiated onto a plurality of irradiation points arranged in the thickness direction (vertical direction) of the first wafer W radially outward from the inner periphery of the peripheral edge portion We to be removed on the first wafer W. "A plurality of irradiation points arranged in the thickness direction" is defined as meaning that the arrangement direction of the plurality of irradiation points includes a thickness direction component. For example, this includes a case where the plurality of irradiation points are arranged in a direction inclined horizontally from the thickness direction as shown in FIG. 5A, and a case where the plurality of irradiation points are arranged in a direction perpendicular to the surface Wa. That is, the first modified region N1 may be arranged in a direction inclined horizontally from the thickness direction as shown in FIG. 5A, or may extend vertically.

[0039] The irradiation point irradiated with the first laser light L1 is modified, forming a first modified region M1, which is a laser mark. When multiple first modified regions M1 are formed, a first crack C1 extends in the direction in which these first modified regions M1 are arranged (a direction inclined horizontally from the thickness direction). The first crack C1 extends to connect between adjacent first modified regions M1. A first modified region N1 including the first modified regions M1 and the first crack C1 is then formed. Note that the lowest first modified region M1 is preferably formed above the bottom surface modified region N21, which will be described later. In this case, the lower end of the first crack C1 can be prevented from extending below the interface between the front surface Wa of the first wafer W and the bonding film Fw (laminated film). However, if the lowermost first modified region M1 can be formed under irradiation conditions of the first laser beam L1 that can prevent the lower end of the first crack C1 from extending downward from the interface between the front surface Wa of the first wafer W and the bonding film Fw (laminated film), the lowermost first modified region M1 may be formed below a bottom surface modified region N21 described later. Moreover, the first laser beam L1 is irradiated to the entire circumference of the first wafer W, and the first modified region N1 is formed along the entire circumference.

[0040] The upper end of the first crack C1 does not reach the back surface Wb of the first wafer W. The lower end of the first crack C1 reaches the interface between the front surface Wa of the first wafer W and the bonding film Fw (laminated film). When forming the first modified region N1, the irradiation conditions such as the output and spacing of the first laser light L1 are controlled so that the first crack C1 extends in this manner.

[0041] Next, as shown in FIG. 5B , a first laser beam L1 is irradiated to multiple irradiation points aligned in the thickness direction of the first wafer W, radially inward from the first modified region N1 along the inner periphery of the peripheral edge We of the first wafer W to be removed, and a first laser beam L1 is irradiated to multiple irradiation points aligned in the surface direction of the first wafer W. Specifically, the first laser beam L1 is irradiated along the side surface of the peripheral edge We (a direction inclined horizontally from the thickness direction), and the first laser beam L1 is irradiated along the bottom surface of the peripheral edge We (a substantially horizontal direction). Note that the second modified region M2 formed along the side surface of the peripheral edge We constitutes a side modified region N22 (described later), and the second modified region M2 formed along the bottom surface of the peripheral edge We constitutes a bottom modified region N21 (described later). Furthermore, the first laser beam L1 is irradiated along the entire periphery of the first wafer W to form a second modified region N2 (described later).

[0042] The irradiation point irradiated with the first laser light L1 is modified, and a second modified region M2, which is a laser mark, is formed. At this time, adjacent second modified regions M2 are not connected to each other. In other words, cracks do not occur in the second modified regions M2, or even if cracks occur, they do not reach adjacent second modified regions M2. Irradiation conditions such as the output and spacing of the first laser light L1 are controlled so that the second modified regions M2 are formed in this way.

[0043] 5B, the first laser light L1 is irradiated to a plurality of irradiation points arranged radially outward from the first modified region N1 in the surface direction (horizontal direction) of the first wafer W. "A plurality of irradiation points arranged in the surface direction" is defined as the arrangement direction of the plurality of irradiation points including a surface direction component, and includes, for example, the case where the plurality of irradiation points are arranged substantially in the surface direction as shown in FIG.

[0044] The irradiation point irradiated with the first laser light L1 is modified, and a third modified region M3, which is a laser mark, is formed. At this time, adjacent third modified regions M3 are not connected to each other. In other words, cracks do not occur in the third modified regions M3, or even if cracks occur, they do not reach adjacent third modified regions M3. The irradiation conditions, such as the output and spacing of the first laser light L1, are controlled so as to form the third modified regions M3 in this manner.

[0045] Furthermore, the third modified region M3 is formed in the vicinity of the front surface Wa of the first wafer W. Then, a third modified region N3 including a plurality of the third modified regions M3 is formed. Furthermore, the first laser light L1 is irradiated onto the entire circumference of the first wafer W, and the third modified region N3 is formed along the entire circumference.

[0046] In this case, the third modified region M3 expands, causing compressive stress to act, and tensile stress to act in the region above the third modified region M3 and the region below the third modified region M3. That is, tensile stress is accumulated in these regions, and tensile stress acts on the front 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 third modified region M3) such that the upper portion of the first wafer W warps obliquely upward so as to peel off the peripheral edge portion We (arrow in FIG. 5B).

[0047] When compressive stress acts in this manner, tensile stress acts on the interface between the surface Wa and the bonding film Fw of the first wafer W, causing the surface Wa and the bonding film Fw to peel off, forming a peeled region P. This peeled region P extends between the first modified region N1 and the outer edge. Note that the peeled region P is not limited to a state in which the interface between the surface Wa and the bonding film Fw is completely peeled off, but also includes, for example, a state in which the bonding strength between the surface Wa and the bonding film Fw is reduced. The peeled region P may also be formed at the interface between the bonding film Fw and the bonding film Fs. For example, if the bonding strength between the surface Wa and the bonding film Fw is weak, the peeled region P is formed at the interface between the surface Wa and the bonding film Fw. If the bonding strength between the bonding film Fw and the bonding film Fs is weak, the peeled region P is formed at the interface between the bonding film Fw and the bonding film Fs.

[0048] As described above, the third modified region M3 is formed in the vicinity of the front surface Wa of the first wafer W, and is formed below the bottom surface modified region N21 of the second modified region N2. In this case, it is possible to prevent the separation region P from being formed below the bottom surface modified region N21, i.e., radially inward of the first modified region N1.

[0049] In the present embodiment, the third modified region M3 (third modified area N3) is formed after the second modified region M2 is formed, but the order in which the second modified region M2 and the third modified region M3 are formed is not limited to this. For example, the second modified region M2 may be formed after the third modified region M3 is formed.

[0050] In addition, in this embodiment, the second modified region M2 is formed after the first modified region M1 (first modified region N1) is formed, but the order in which the first modified region M1 and the second modified region M2 are formed is not limited to this. For example, the first modified region M1 may be formed after the second modified region M2 is formed. However, as described below, it is preferable to form the first modified region M1 (first modified region N1) before forming the second crack C2 by irradiating the first laser light L1 again, as described below.

[0051] In addition, in this embodiment, the third modified region M3 (third modified region N3) is formed after the first modified region M1 (first modified region N1), but the order of forming the first modified region M1 and the third modified region M3 is not limited to this. However, since forming the first modified region M1 (first modified region N1) can prevent the third modified region M3 from being formed radially inward, it is preferable to form the first modified region M1 first.

[0052] Next, as shown in Fig. 5(c), the first laser beam L1 is irradiated again along the bottom surface of the peripheral edge portion We. At this time, the first laser beam L1 may be irradiated at the same position as the second modified region M2 formed along the bottom surface of the peripheral edge portion We, or may be irradiated at a position different from the second modified region M2.

[0053] In this case, a second crack C2 extends from the second modified region M2 along the bottom surface of the peripheral edge portion We, forming a bottom surface modified region N21 including the second modified region M2 and the second crack C2. The radially outer end of this second crack C2 is connected to the first modified region N1. It is preferable that the second crack C2 does not pass through the first modified region N1. Therefore, the irradiation conditions, such as the output power and spacing of the first laser light L1, or the distance between the outermost second modified region M2 and the first modified region N1, may be set so that the second crack C2 does not pass through the first modified region N1 and extend therethrough. Furthermore, the irradiation conditions, such as the output power and spacing of the first laser light L1, or the distance between the outermost second modified region M2 and the first modified region N1 may be set depending on the crystal orientation of the first wafer W. For example, when the second crack C2 is likely to propagate due to the crystal orientation, the distance between the outermost second modified region M2 and the first modified region N1 is increased compared to when the second crack C2 is unlikely to propagate due to the crystal orientation. Furthermore, the second crack C2 connects the second modified region M2 along the side surface of the peripheral edge We from the radially inner end, propagates along the side surface of the peripheral edge We, and reaches the back surface Wb of the first wafer W. A side modified region N22 is then formed, including the second modified region M2 and the second crack C2 along the side surface of the peripheral edge We. The bottom modified region N21 and the side modified region N22 constitute the second modified region N2.

[0054] In this embodiment, the first laser beam L1 is irradiated onto a plurality of irradiation points aligned in the bottom surface modified region N21, but the first laser beam L1 may also be irradiated onto a plurality of irradiation points aligned in the side surface modified region N22. Furthermore, although the second modified region N2 in this embodiment includes the bottom surface modified region N21 and the side surface modified region N22, for example, the side surface modified region N22 may be omitted, and the bottom surface modified region N21 may be directly connected to the first modified region N1.

[0055] Next, the overlapped wafer T on which the first modified region N1, the second modified region N2, and the third modified region N3 (peeling region P) have been formed is transferred by the wafer transfer device 40 to the edge removal device 70. In the edge removal device 70, the edge removal unit (remover) removes the edge portion We from the first wafer W, as shown in FIG. 5( d ). For example, a blade B is inserted between the first wafer W and the second wafer S, and the edge portion We is removed from the first wafer W. At this time, the edge portion We is peeled and removed from the central portion We of the first wafer W, using the first modified region N1, the second modified region N2, and the peeling region P as base points.

[0056] Next, the overlapped wafer T from which the peripheral edge portion We has been removed is transported by the wafer transport device 40 to the second laser irradiation device 60. In the second laser irradiation device 60, as shown in FIG. 5E, the second laser light L2 is irradiated onto the surface film (bonding films Fw, Fs and device layers Dw, Ds) on the peripheral portion of the surface Sa of the second wafer S. The peripheral portion of the surface Sa of the second wafer S is the region from the radially outer side of the first modified region N1 to the outer edge, in other words, the peeled region P. The second laser light L2 then removes the surface film on the peripheral portion of the surface Sa of the second wafer S by laser ablation. In the laser ablation process, the surface film on the surface Sa of the first wafer W and the second wafer S below the bottom surface modified region N21 may be removed. Alternatively, the laser ablation process itself may be omitted.

[0057] Next, the laminated wafer T from which the surface film on the peripheral portion of the surface Sa of the second wafer S has been removed is transferred by the wafer transfer device 40 to the cleaning device 80. In the cleaning device 80, the first wafer W and the second wafer S are cleaned.

[0058] Thereafter, the laminated wafer T that has been subjected to all the processes is transferred by the wafer transfer device 40 to the transition stage 30, and further transferred by the wafer transfer device 20 to the FOUP F on the FOUP mounting table 10. In this way, the series of wafer processes in the wafer processing system 1 is completed.

[0059] Here, when a modified region is formed along the boundary between the peripheral portion and the central portion of the first wafer to be removed, i.e., in the thickness direction, the upper end of a crack in the modified region may reach the back surface of the first wafer. In such a case, the pressure of the crack is released on the back surface of the first wafer, causing the crack to extend downward from the front surface of the first wafer, and the lower end of the crack may reach the second wafer. This crack may then damage the second wafer.

[0060] 5A, in this embodiment, a first modified region N1 is formed inside the peripheral edge portion We of the first wafer W. The upper ends of the first cracks C1 in the first modified region N1 do not reach the back surface Wb of the first wafer W, and therefore the lower ends of the first cracks C1 do not extend below the interface between the front surface Wa of the first wafer W and the bonding film Fw. This makes it possible to prevent the second wafer S from being damaged by the first cracks C1.

[0061] According to this embodiment, a second modified region N2 is formed inside the first wafer W as shown in FIGS. 5B and 5C. The second modified region N2 forms a side modified region N22 extending in the thickness direction, and one end of the second crack C2 in the second modified region N2 reaches the back surface Wb of the first wafer W. The second modified region N2 also forms a bottom modified region N21 extending in the surface direction, and the other end of the second crack C2 in the second modified region N2 is connected to the first modified region N1. As a result, the modified region including the first modified region N1 and the second modified region N2 penetrates the first wafer W in the thickness direction. Furthermore, according to this embodiment, a third modified region N3 is formed inside the first wafer W near the front surface Wa as shown in FIG. 5B. This allows a separation region P to be formed at the interface between the front surface Wa of the first wafer W and the bonding film Fw. In such a case, as shown in FIG. 5(d), in the peripheral edge removal device 70, the peripheral edge We can be appropriately peeled and removed from the first wafer W using the first modified region N1, the second modified region N2, and the peeling region P as starting points.

[0062] 5B, the second crack C2 may be extended to connect adjacent second modified regions M2 while the second modified regions M2 are being formed one by one. However, in this case, since the second crack C2 is extended by forming the second modified regions M2 one by one, it is difficult to determine the extension target of the second crack C2.

[0063] In this regard, according to the present embodiment, when forming the second modified region N2, the second laser beam L2 is irradiated onto the interior of the first wafer W to form the second modified region M2 as shown in Fig. 5(b), and then the second laser beam L2 is irradiated onto the interior of the first wafer W again to extend the second crack C2 as shown in Fig. 5(c). In this case, the extension target of the second crack C2 is the adjacent second modified region M2, so that the second crack C2 is prevented from extending in a direction other than the desired direction, and the second modified region N2 can be formed in an appropriate direction.

[0064] Before the above-described wafer processing is performed in the wafer processing system 1, the overlapped wafer T may have a back surface film (e.g., an oxide film) formed on the back surface Wb (upper surface) of the first wafer W. If such a back surface film is formed, the first laser beam L1 may be obstructed by the back surface film in the first laser irradiation device 50 and may not be irradiated to an appropriate position. Furthermore, the second laser beam L2 may also not be irradiated to an appropriate position in the second laser irradiation device 60. Therefore, the back surface film may be removed before the irradiation process of the first laser beam L1 in the first laser irradiation device 50. For example, the second laser irradiation device 60 irradiates the back surface film (not shown) with the second laser beam L2, and the back surface film is removed by laser ablation using the second laser beam L2.

[0065] Furthermore, in this embodiment, after wafer processing is performed in the wafer processing system 1, processing to thin the central portion Wc of the first wafer W is performed outside the wafer processing system 1. Any processing method can be used to thin the first wafer W. For example, when the central portion Wc of the first wafer W is thinned by grinding, a grinding device (not shown) that is a thinning device may be provided outside the wafer processing system 1 or may be installed in the wafer processing system 1.

[0066] Next, a wafer processing according to a second embodiment will be described. In the second embodiment, instead of the third modified region N3 and the separation region P of the first embodiment, a bonding strength reduced region R is formed at the interface between the first wafer W and the second wafer S as shown in FIG. 6. The bonding strength reduced region R corresponds to the third modified region in the present disclosure.

[0067] The formation of the bonding strength reduced region R is performed, for example, by a third laser irradiation device (not shown) provided in the wafer processing system 1. The configuration of the third laser irradiation device is not particularly limited, but in one example, the third laser irradiation device has a configuration similar to that of the first laser irradiation device 50. The third laser irradiation device is configured to be able to irradiate third laser light L3 (interface laser light, for example, a CO2 laser).

[0068] In the wafer processing according to the second embodiment, first, a third laser irradiation device irradiates a third laser beam L3 along the interface between the first wafer W and the second wafer S (the interface between the front surface Wa of the first wafer W and the bonding film Fw in the illustrated example) as shown in FIG. 6A. The portion irradiated with the third laser beam L3 is modified, forming a bonding strength reduced region R in which the bonding strength between the first wafer W and the second wafer S is reduced. Note that in this embodiment, the "interface between the first wafer W and the second wafer S" includes the respective interfaces and interiors of the first wafer W, the device layer Dw (including the laser absorption layer for peeling included in the device layer Dw), Ds, the bonding films Fw and Fs, and the second wafer S. In other words, the position where the bonding strength reduced region R is formed is not particularly limited as long as the bonding strength between the first wafer W and the second wafer S can be reduced.

[0069] When forming the bonding strength reduced region R, it is preferable that a laser absorption layer be formed at a position where the third laser light L3 is irradiated. That is, it is preferable that the laminated film on the front surface Wa of the first wafer W includes a laser absorption layer. In this case, the bonding strength reduced region R can be formed at a more appropriate position.

[0070] Next, in the first laser irradiation device 50, a first modified region N1 is formed as shown in FIG. 6B. The method for forming this first modified region N1 is the same as the method for forming the first modified region N1 in the first embodiment. In this embodiment, the first crack C1 in the first modified region N1 extends to the bonding strength reduced region R to connect it. However, because the upper end of the first crack C1 does not reach the back surface Wb of the first wafer W, the first crack C1 does not extend below the bonding strength reduced region R to reach the second wafer S.

[0071] Next, the second modified region N2 (bottom surface modified region N21 and side surface modified region N22) is formed as shown in Fig. 6(c) in the first laser irradiation device 50. The method for forming this second modified region N2 is the same as the method for forming the second modified region N2 in the first embodiment.

[0072] Next, in the edge removal device 70, the edge portion We is peeled off and removed from the first wafer W, using the first modified region N1, the second modified region N2, and the bonding strength reduced region R as base points, as shown in FIG. 6(d).

[0073] Next, in the second laser irradiation device 60, the surface film on the peripheral portion of the surface Sa of the second wafer S is removed by laser ablation, as shown in Fig. 6(e) . This laser ablation process is similar to the laser ablation process according to the first embodiment.

[0074] In this embodiment, the first modified region N1 is formed after the bonding strength reduced region R, but the order of forming the bonding strength reduced region R and the first modified region N1 is not limited to this. For example, the bonding strength reduced region R may be formed after the first modified region N1 is formed.

[0075] In the second embodiment described above, the same effects as in the first embodiment can be obtained.

[0076] Next, a description will be given of wafer processing according to the third embodiment. In the third embodiment, as shown in Fig. 7, the third modified region N3 and the separation region P of the first embodiment are not formed.

[0077] In wafer processing according to the third embodiment, first, a first modified region N1 is formed in a first laser irradiation device 50 as shown in Fig. 7(a). The method for forming this first modified region N1 is the same as the method for forming the first modified region N1 in the first embodiment. As described above, the first modified region N1 may be aligned in a direction inclined horizontally from the thickness direction, or may extend vertically relative to the surface Wa. In the example shown in Fig. 7(a), the first modified region N1 extends vertically.

[0078] The inventors have found through their investigation that the first crack C1 is more likely to extend when the first modified region N1 extends in the vertical direction as in the present embodiment. Therefore, in the first embodiment, the first modified region N1 may extend in the vertical direction as in the third embodiment.

[0079] Next, a second modified region M2 is formed as shown in Fig. 7(b), and the second crack C2 is extended to form a second modified region N2 (a bottom modified region N21 and a side modified region N22) as shown in Fig. 7(c). The method for forming this second modified region N2 is the same as the method for forming the second modified region N2 in the first embodiment.

[0080] As shown in FIG. 7C , the second crack C2 is extended until one end of the second crack C2 reaches the back surface Wb of the first wafer W and the other end connects to the first modified region N1. When the second crack C2 connects to the first modified region N1, the pressure of the second crack C2 is released. Then, a tensile stress G acts upward on the interface between the front surface Wa of the first wafer W and the bonding film Fw, radially outward from the first modified region N1. This tensile stress G causes a peeled region Q to form at the interface between the front surface Wa and the bonding film Fw. The peeled region Q is not limited to a state in which the interface between the front surface Wa and the bonding film Fw is completely peeled off, but also includes, for example, a state in which the bonding strength between the front surface Wa and the bonding film Fw is reduced. The peeled region Q may also be formed at the interface between the bonding film Fw and the bonding film Fs. For example, if the bonding strength between the surface Wa and the bonding film Fw is weak, a peeling region Q is formed at the interface between the surface Wa and the bonding film Fw, and if the bonding strength between the bonding film Fw and the bonding film Fs is weak, a peeling region Q is formed at the interface between the bonding film Fw and the bonding film Fs.

[0081] Next, in the edge removal device 70, the edge We is peeled off and removed from the first wafer W, using the first modified region N1, the second modified region N2 and the peeled region Q as base points, as shown in FIG. 7D.

[0082] Next, in the second laser irradiation device 60, the surface film on the peripheral portion of the surface Sa of the second wafer S is removed by laser ablation, as shown in Fig. 7(e) . This laser ablation process is similar to the laser ablation process according to the first embodiment.

[0083] In the third embodiment, the same effects as in the first embodiment can be obtained.

[0084] Furthermore, since the third modified region N3 is not formed compared to the first embodiment, the laser processing time using the first laser light L1 in the first laser irradiation device 50 can be shortened, further improving the throughput of wafer processing.

[0085] Furthermore, the peeled region Q can be formed without irradiating the first laser light L1 near the surface Wa of the first wafer W, i.e., the first laser light L1 is not irradiated onto the surface Sa of the second wafer S. Therefore, laser marks (processing marks) are not formed on the surface Sa of the second wafer S by the first laser light L1, and damage to the second wafer S can be suppressed.

[0086] Next, a description will be given of wafer processing according to the fourth embodiment. In the fourth embodiment, as shown in Fig. 8, the peripheral edge portion We is removed from the first wafer W, using the first modified region N1 and the separation region Q as base points.

[0087] In wafer processing according to the fourth embodiment, first, a first modified region N1 is formed in the first laser irradiation device 50 as shown in Fig. 8(a). The method for forming this first modified region N1 is the same as the method for forming the first modified region N1 in the third embodiment. As described above, the first modified region N1 may be aligned in a direction inclined horizontally from the thickness direction, or may extend vertically relative to the surface Wa. In the example shown in Fig. 8(a), the first modified region N1 extends vertically.

[0088] The upper end of the first crack C1 reaches the uppermost first modified portion M1a but does not reach the back surface Wb of the first wafer W. The lower end of the first crack C1 reaches the interface between the front surface Wa of the first wafer W and the bonding film Fw (laminated film). When forming the first modified region N1, the irradiation conditions such as the output and spacing of the first laser light L1 are controlled so that the first crack C1 extends in this manner.

[0089] Next, a second modified region M2 is formed as shown in FIG. 8(b), and the second crack C2 is extended to form a second modified region N2 (bottom modified region N21 and side modified region N22) as shown in FIG. 8(c). The method for forming this second modified region N2 is the same as the method for forming the second modified region N2 in the third embodiment. Furthermore, a tensile stress G acts on the second crack C2, forming a peeled region Q.

[0090] Next, in the peripheral edge removal device 70, a blade B is inserted between the first wafer W and the second wafer S, as shown in FIG. 8(d), for example. This causes a first crack C1a to extend upward from the uppermost first modified portion M1a in the first modified region N1 and reach the back surface Wb of the first wafer W. Then, the peripheral edge We is peeled and removed from the first wafer W, using the first modified region N1 and the peeled region Q as base points.

[0091] In this embodiment, before the first wafer W (hatched portion in FIG. 8(d)) in the area surrounded by the second modified region N2 and the first modified region N1 is removed, the first crack C1a extends to the back surface Wb and the peripheral portion We is removed. The second modified region N2 is then removed, for example, when the central portion Wc of the first wafer W is thinned (e.g., ground) outside the wafer processing system 1. Therefore, the bottom surface modified region N21 of the second modified region N2 is located above the thinned surface (e.g., grinding surface).

[0092] Next, in the second laser irradiation device 60, the surface film on the peripheral portion of the surface Sa of the second wafer S is removed by laser ablation, as shown in Fig. 8(e) . This laser ablation process is similar to the laser ablation process according to the first embodiment.

[0093] In the fourth embodiment described above, the same effects as in the third embodiment can be obtained.

[0094] Furthermore, when removing the peripheral edge portion We from the first wafer W, the removal surface of the peripheral edge portion We becomes the first modified region N1, so the area of ​​the removal surface is reduced compared to when removal is performed starting from the second modified region N2. Also, the number of first modified regions M1 exposed by removing the peripheral edge portion We is smaller than the number of second modified regions M2. This makes it possible to reduce particles generated when removing the peripheral edge portion We.

[0095] Next, a wafer process according to the fifth embodiment will be described. In the fifth embodiment, as shown in FIG. 9, the separation region P of the first embodiment is not formed.

[0096] In wafer processing according to the fifth embodiment, first, a first modified region N1 is formed in a first laser irradiation device 50 as shown in FIG. 9A. The method for forming this first modified region N1 is the same as the method for forming the first modified region N1 in the first embodiment. In this embodiment, the first crack C1 in the first modified region N1 is caused to reach the unbonded region Ae. As described above, because the peripheral edge We of the first wafer W and the peripheral edge of the second wafer S are each chamfered, an unbonded region Ae exists in the peripheral edge of the overlapped wafer T, where the first wafer W and the second wafer S are not bonded.

[0097] 9B, a second modified region M2 is formed. The method for forming this second modified region M2 is the same as the method for forming the second modified region M2 in the first embodiment. Note that a third modified region M3 (described later) may be formed immediately after the formation of the second modified region M2 in the bottom surface modified region N21.

[0098] 9B, a third modified region M3 is formed to form a third modified region N3. The method for forming this third modified region N3 is the same as the method for forming the third modified region N3 in the first embodiment. In this embodiment, the thickness direction position of the second modified region M2 and the thickness direction position of the third modified region M3 are the same.

[0099] In this embodiment, the first modified region N1 intersects with the bottom surface modified region N21 and the third modified region N3. In this case, the first crack C1 in the first modified region N1 is likely to propagate, and the second crack C2 in the bottom surface modified region N21 is likely to propagate.

[0100] In this embodiment, the formation of the third modified region N3 (third modified portion M3) may be omitted. Alternatively, the third modified region N3 may extend radially outward from the first modified region N1, and may not necessarily extend to the outer edge.

[0101] Next, as shown in Fig. 9(c), the second crack C2 is extended from the second modified portion M2 to form the second modified region N2 (bottom surface modified region N21 and side surface modified region N22). The method for forming this second modified region N2 is the same as the method for forming the second modified region N2 in the first embodiment.

[0102] 9(d), the peripheral edge removal device 70 peels and removes the peripheral edge We from the first wafer W, using the first modified region N1 and the second modified region N2 as base points. At this time, because the upper end of the first crack C1 in the first modified region N1 does not reach the back surface Wb of the first wafer W, peeling does not occur on the radially outer side of the peripheral edge We, and the peripheral edge We can be appropriately removed.

[0103] Next, in the second laser irradiation device 60, the first wafer W remaining below the bottom surface modified region N21 and the surface film on the peripheral portion of the surface Sa of the second wafer S are removed by laser ablation, as shown in Fig. 9(e) . This laser ablation process is the same as the laser ablation process according to the first embodiment.

[0104] In the fifth embodiment described above, the same effects as in the first embodiment can be obtained.

[0105] In the first to fifth embodiments described above, when forming the second modified region M2, the first wafer W is irradiated with the first laser beam L1 in pulses while the chuck 100 (superimposed wafer T) is rotated by the rotation mechanism 103. As shown in FIG. 10 , the chuck 100 is rotated 360°, and the first laser beam L1 is irradiated in an annular shape to form an annular modified region A in which the second modified region M2 is arranged in an annular shape. Next, the chuck 100 is moved radially by the movement mechanism 104, and then the chuck 100 is further rotated 360°, and the first laser beam L1 is irradiated in an annular shape to form the annular modified region A. The 360° rotation of the chuck 100, the irradiation of the first laser beam L1 (forming the second modified region M2), and the radial movement of the chuck 100 are alternately repeated to form a plurality of annular modified regions A of different diameters concentric with the first wafer W at the peripheral edge We.

[0106] In the second modified region N2, the bottom surface modified region N21 formed in the circumferential direction of the first wafer W constitutes an annular modified region A. Similarly, in the second modified region N2, the side surface modified region N22 formed in the circumferential direction of the first wafer W constitutes an annular modified region A. In other words, the second modified region N2 includes multiple annular modified regions A.

[0107] In the following description, among the multiple annular modified regions A, the nth annular modified region A from the innermost (first) region radially outward is referred to as the annular modified region A. ｎ In addition, each annular modified region A ｎ In this case, the position where the irradiation of the first laser light L1 starts is designated as the irradiation start position J ｎ The position where the irradiation of the first laser light L1 ends is called the irradiation end position K ｎ In addition, these irradiation start positions J ｎ and irradiation end position K ｎ The area between the light gap H ｎ So, this light gap H ｎ is not irradiated with the first laser light L1.

[0108] As a comparative example, for example, as shown in FIG. ｎare formed in a line in one radial direction (Y-axis direction), singular points that are not irradiated with the first laser light L1 are densely concentrated in the one radial direction. ｎ are densely packed and the light gap H ｎ When the area of ​​the light gap H increases, the area where the first laser light L1 is not irradiated increases. ｎ If the distance is made as small as possible, it may be difficult to control the irradiation position of the first laser beam L1, resulting in some areas being irradiated with overlapping first laser beams. As a result, unevenness may occur at the interface of the annular modified region A of the second modified region N2 in the first wafer W after the peripheral edge We has been removed. If unevenness occurs on the first wafer W, it may cause unnecessary strain on the grinding tool during subsequent grinding. Furthermore, if etching is performed subsequently, the desired etching process may not be achieved. Furthermore, even after the first wafer W is ground and thinned, unevenness may remain on the back surface Wb of the thinned first wafer W. Furthermore, when the back surface Wb is subsequently wet-etched, the etching solution may penetrate into the recesses, resulting in the desired etching process not being achieved.

[0109] Therefore, in this embodiment, as shown in FIG. 10, adjacent annular modified regions A ｎ－１ , A ｎ In this case, the optical gap H in one radial direction (Y-axis direction) ｎ－１ , H ｎ The optical gap H ｎ－１ , H ｎ That is, the annular modified region A １ , ...A ｎ－１ , A ｎ In this case, the optical gap H １ , ...H ｎ－１ , H ｎ In this case, the singular points where the first laser beam L1 is not irradiated can be dispersed in the circumferential direction, and the light gap H ｎ As a result, it is possible to suppress irregularities occurring on the first wafer W after the peripheral edge portion We is removed.

[0110] Specifically, the first laser beam L1 is irradiated to form a circular ring-shaped modified region A ｎ－１After forming the annular modified region A, the chuck 100 is moved in the radial direction. ｎ－１ The first laser beam L1 is irradiated to the radially outer side of the circular modified region A. ｎ That is, the first laser light L1 is irradiated in the radial direction of the first wafer W to form an annular modified region A. At this time, the chuck 100 is kept rotating while moving in the radial direction. Then, when the radial movement of the chuck 100 is completed, the position where the first laser light L1 is irradiated becomes the irradiation start position J. ｎ It is preferable to control at least one of the speed of the radial movement of the chuck 100 and the rotation speed of the chuck 100 so that the laser processing time is reduced and the throughput of the wafer processing is improved. Note that the rotation of the chuck 100 may be stopped while the chuck 100 is being moved in the radial direction.

[0111] Annular modified area A １ , ...A ｎ－１ , A ｎ In this case, the optical gap H １ , ...H ｎ－１ , H ｎ are preferably arranged at equal intervals (circumferential interval E1 in the example of FIG. 10). １ , ...H ｎ－１ , H ｎ For example, the optical gap H １ , ...H ｎ－１ , H ｎ In order to disperse the circumferential positions of the irradiation start position J １ , ...J ｎ－１ , J ｎ Alternatively, the circumferential position of the first and second electrodes may be changed by a predetermined angle (a predetermined angle other than 360 degrees).

[0112] In this embodiment, at least adjacent annular modified regions A ｎ－１ , A ｎ In this case, the optical gap H in one radial direction ｎ－１ , H ｎ For example, the annular modified region A １ and annular modified region A ｎIf they are far enough apart, the optical gap H １ and light gap H ｎ may be at the same circumferential position.

[0113] Adjacent light gap H ｎ－１ , H ｎ The circumferential interval E1 between the light gaps H ｎ－１ , H ｎ The circumferential interval E1 between the first laser beam L1 and the second laser beam L2 may be equal to or greater than the pulse interval E3 of the first laser beam L1. ｎ－１ , H ｎ The circumferential position of the light gap H may be set as an angle from one radial direction (Y-axis direction) passing through the notch of the first wafer W. For example, ｎ－１ The angle is set to 5 degrees, and the light gap H ｎ－１ The angle may be set to 10 degrees.

[0114] Each light gap H １ , ...H ｎ－１ , H ｎ The circumferential distance E2 is arbitrary as long as it is a distance at which the first laser beams L1 do not overlap.

[0115] The pulse interval (circumferential interval) E3 of the first laser light L1 is, for example, 20 μm or less. The index interval (radial interval) E4 of the first laser light L1 is, for example, 20 μm or less. For example, the pulse interval E3 and the index interval E4 of the first laser light L1 may be the same or different.

[0116] According to this embodiment, adjacent annular modified regions A ｎ－１ , A ｎ In this case, the optical gap H in one radial direction ｎ－１ , H ｎ Since the circumferential positions of the first wafer W and the second wafer W are different, it is possible to suppress irregularities occurring on the first wafer W after the peripheral edge portion We is removed. As a result, grinding of the rear surface Wb of the subsequent first wafer W and wet etching of the rear surface Wb can also be performed appropriately.

[0117] In this embodiment, in the second modified region N2, both the bottom surface modified region N21 and the side surface modified region N22 are circular ring modified regions A. ｎ－１ , A ｎIn this case, the optical gap H in one radial direction (Y-axis direction) ｎ－１ , H ｎ In another embodiment, the optical gap H is formed only in the bottom surface modified region N21. ｎ－１ , H ｎ For example, if the side surface modified region N22 is located above the grinding position during subsequent grinding, it is not directly related to the irregularities that occur on the first wafer W after the peripheral edge We is removed. Therefore, the side surface modified region N22 is not directly related to the optical gap H ｎ－１ , H ｎ The circumferential positions of the first and second grooves do not have to be different.

[0118] 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.

[0119] Furthermore, the effects described in this specification are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0120] 1 Wafer processing system 50 First laser irradiation device 51 Control device 90 Control device 110 Laser irradiation section C1 First crack C2 Second crack M1 First modified section M2 Second modified section N1 First modified region N2 Second modified region S Second wafer T Overlapped wafer W First wafer Wa Front surface Wb Back surface Wc Center We Peripheral edge

Claims

1. A substrate processing system for processing an overlapped substrate formed by bonding a first substrate and a second substrate, the substrate processing system comprising: a laser irradiation unit that irradiates laser light; and a control unit, wherein the control unit performs the following controls: control to form a first modified region including a first modified portion modified by irradiating a plurality of points aligned in the thickness direction of the first substrate with a laser radially outward from the inner periphery of a peripheral portion of the first substrate to be removed or along the peripheral portion with the laser, and a first crack extending from the first modified portion; control to prevent the first crack from reaching the back surface of the first substrate on the side opposite the second substrate; control to form a second modified region including a second modified portion modified by irradiating a plurality of points aligned in the thickness direction of the first substrate with the laser radially inward from the first modified region, and a second crack extending from the second modified portion; and control to cause the second crack to reach the back surface of the first substrate and connect to the first modified region.

2. A substrate processing system as described in claim 1, which has a peripheral removal section that removes the peripheral portion based on the first modified area and the second modified area when the first modified area is formed radially outward from the inner circumference of the peripheral portion.

3. The substrate processing system of claim 1, wherein the control unit, when forming the first modified region along the peripheral edge portion, executes control to cause the first crack to reach the back surface of the first substrate to form the first modified region, and the substrate processing system has a peripheral edge removal unit that removes the peripheral edge portion based on the first modified region.

4. The substrate processing system of claim 1, wherein a laminated film is formed on the surface of the first substrate facing the second substrate, and the control unit executes control to cause the first crack to reach the interface between the surface of the first substrate and the laminated film.

5. The substrate processing system according to claim 1, wherein the control unit executes control to cause the first crack to reach an unbonded region where the first substrate and the second substrate are not bonded.

6. The substrate processing system of claim 1, wherein the control unit, when forming the second modified region, executes control to irradiate a portion of the second modified region with a laser after forming the second modified region, thereby extending the second crack.

7. A substrate processing system as described in claim 6, wherein the second modified region includes a bottom modified region extending along the bottom surface of the peripheral portion and a side modified region extending along the side surface of the peripheral portion, and the control unit performs control to irradiate the bottom modified region with laser light and extend the second crack.

8. The substrate processing system of claim 1, wherein the control unit executes control to form a third modified region by irradiating laser onto multiple points aligned in the surface direction of the first substrate radially outward from the first modified region.

9. The substrate processing system of claim 1, wherein the second modified region includes an annular modified region formed by irradiating the laser light onto a plurality of annular regions having different diameters in a planar view, and the second modified portions are arranged in an annular shape, and the annular modified region has a light gap between a start position of the laser light irradiation and a stop position of the laser light irradiation, and the circumferential position of the light gap relative to one radial direction of the first substrate is different in adjacent annular modified regions.

10. The substrate processing system according to claim 9, wherein the circumferential distance of the light gap is at least a distance such that the laser beams do not overlap.

11. The substrate processing system according to claim 9, wherein the annular modified regions are formed in a row along the bottom surface of the peripheral portion.

12. The substrate processing system according to claim 9, wherein the annular modified regions are formed in a row along a side surface of the peripheral edge portion.

13. A substrate processing method for processing an overlapped substrate formed by bonding a first substrate and a second substrate, comprising: forming a first modified region including a first modified portion modified by irradiating a laser at multiple points aligned in the thickness direction of the first substrate radially outward from the inner periphery of a peripheral portion of the first substrate to be removed or along the peripheral portion, and a first crack extending from the first modified portion toward the second substrate; and forming a second modified region radially inward from the first modified region, including a second modified portion modified by irradiating a multiple points aligned in the thickness direction of the first substrate with a laser, and a second crack extending from the second modified portion; wherein the substrate processing method does not allow the first crack to reach the back surface of the first substrate opposite the second substrate, and allows the second crack to reach the back surface of the first substrate and connect to the first modified region.

14. A substrate processing method as described in claim 13, which includes removing the peripheral portion from the first modified region and the second modified region as starting points when forming the first modified region radially outward from the inner periphery of the peripheral portion.

15. A substrate processing method as described in claim 13, comprising, when forming the first modified region along the peripheral edge portion, causing the first crack to reach the back surface of the first substrate to form the first modified region, and removing the peripheral edge portion using the first modified region as a starting point.

16. The substrate processing method according to claim 13, wherein a laminated film is formed on the surface of the first substrate facing the second substrate, and the first crack is caused to reach the interface between the surface of the first substrate and the laminated film.

17. The substrate processing method according to claim 13, wherein the first crack is caused to reach an unbonded region where the first substrate and the second substrate are not bonded.

18. A substrate processing method according to claim 13, wherein when forming the second modified region, after forming the second modified portion, a laser is irradiated onto a portion of the second modified region to extend the second crack.

19. A substrate processing method as described in claim 18, wherein the second modified region includes a bottom modified region extending along the bottom surface of the peripheral portion and a side modified region extending along the side surface of the peripheral portion, and the bottom modified region is irradiated with a laser to extend the second crack.

20. A substrate processing method according to claim 13, further comprising forming a third modified region by irradiating a laser beam onto a plurality of points aligned in the surface direction of the first substrate radially outward from the first modified region.

21. A substrate processing method as described in claim 13, wherein the second modified region includes an annular modified region formed by irradiating laser light onto a plurality of annular regions having different diameters in a planar view, and the second modified portions are arranged in an annular shape, the annular modified region having an optical gap between a position where irradiation of the laser light starts and a position where irradiation of the laser light ends, and the circumferential position of the optical gap relative to one radial direction of the first substrate is different in adjacent annular modified regions.

22. The substrate processing method according to claim 21, wherein the circumferential distance of the light gap is at least a distance such that the laser beams do not overlap.

23. The substrate processing method according to claim 21, wherein the annular modified regions are formed in a row along the bottom surface of the peripheral edge portion.

24. The substrate processing method according to claim 21, wherein the annular modified regions are formed in a row along a side surface of the peripheral edge portion.

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