Substrate processing method and substrate processing system

Abstract

According to the present invention, a substrate processing method for processing a stacked substrate obtained by joining a first substrate and a second substrate involves: forming a first circumferential edge modified region inside the first substrate along a side surface of a circumferential edge upper part of the first substrate that is to be removed; forming a second circumferential edge modified region inside the first substrate along a bottom surface of the circumferential edge upper part; removing the circumferential edge upper part from the first substrate from the first circumferential edge modified region and the second circumferential edge modified region, leaving a circumferential edge lower part of the first substrate that is below the circumferential edge upper part; grinding a center part of the first substrate that is on the inside in the radial direction of the circumferential edge upper part that has been removed; and etching the entire surface of the first substrate that has been ground at the center part, including the circumferential edge lower part.

Description

Substrate processing method and substrate processing system

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

[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, and a peripheral edge removing device for removing the peripheral edge 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 performs a thinning process on the first substrate 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 method for processing an overlapped substrate in which a first substrate and a second substrate are bonded together, the method including: forming a first peripheral modified region inside the first substrate along a side surface of the upper peripheral edge to be removed in the first substrate; forming a second peripheral modified region inside the first substrate along a bottom surface of the upper peripheral edge; removing the upper peripheral edge from the first substrate using the first peripheral modified region and the second peripheral modified region as base points, leaving a lower peripheral edge below the upper peripheral edge in the first substrate; grinding a central portion of the first substrate radially inward of the removed upper peripheral edge; and etching the entire surface of the first substrate from which the central portion has been ground, including the lower peripheral edge.

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

[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 plan view showing an outline of the configuration of a laser irradiation device; FIG. 4 is a side view showing an outline of the configuration of a laser irradiation device; FIG. 5 is a flow diagram showing main steps of wafer processing; FIG. 6 is an explanatory diagram showing main steps of wafer processing; FIG. 7 is an explanatory diagram of a first peripheral modified region and divided modified regions; FIG. 8 is an explanatory diagram showing main steps of wafer processing; FIG. 9 is an explanatory diagram of a second peripheral modified region according to another embodiment; FIG. 10 is an explanatory diagram of a second peripheral modified region according to another embodiment; FIG. 11 is a plan view showing an outline of the configuration of a wafer processing system according to another embodiment.

[0008] In the manufacturing process of semiconductor devices, a first wafer, which is a semiconductor substrate (hereinafter referred to as a "wafer") having a plurality of devices such as electronic circuits formed on its surface, is bonded to a second wafer to form a laminated wafer, and the first wafer is thinned. Before the thinning process of the first wafer, a process called edge trimming is performed to remove the peripheral portion of the first wafer.

[0009] The edge trimming of the first wafer is performed using a substrate processing system disclosed in, for example, Patent Documents 1 to 3. In the substrate processing system, a laser beam is irradiated along the boundary between the peripheral portion and the central portion of the first wafer to be removed, forming a modified layer inside the first wafer. Then, in a peripheral removal device, the peripheral portion of the first wafer is removed starting from the modified layer.

[0010] Depending on the arrangement of the modified layer on the first wafer, residue of the first wafer may remain below the peripheral edge after the peripheral edge is removed. Conventionally, such residue has been removed by, for example, irradiating the first wafer with a laser or performing wet etching. Then, the center of the first wafer is ground, and the surface of the first wafer is etched.

[0011] However, removing the residue from the first wafer in this manner exposes the surface of the second wafer, which makes the exposed surface of the second wafer more susceptible to etching when etching the surface of the first wafer. Therefore, there is room for improvement in the conventional thinning process for the first wafer.

[0012] The technology disclosed herein appropriately performs a thinning process on a first substrate in a laminated substrate formed by bonding a first substrate and a second substrate. 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.

[0013] 1 , a wafer processing system 10 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.

[0014] The first wafer W is a semiconductor wafer such as a silicon substrate, and at least one film is laminated on the front surface Wa side. Hereinafter, the film formed on the front surface Wa side 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 a plurality of devices. The bonding film Fw may include, for example, an oxide film (THOX film, SiO ２ The first wafer W is bonded to the second wafer S via a bonding film Fw. The peripheral edge We of the first wafer W is chamfered, and the thickness of the cross section of the peripheral edge We decreases toward its tip. In the following description, the region of the first wafer W radially inward from the peripheral edge We to be removed may be referred to as the central region Wc.

[0015] 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.

[0016] 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.

[0017] As shown in FIG. 2, the wafer processing system 10 includes a first wafer processing system 11 and a second wafer processing system 12 .

[0018] The first wafer processing system 11 has a configuration in which a carry-in / out station 20 and a processing station 21 are integrally connected. In the carry-in / out station 20, for example, a FOUP F capable of accommodating a plurality of overlapped wafers T is carried in and out between the outside and the system. The processing station 21 is equipped with various processing devices that perform desired processing on the overlapped wafers T.

[0019] The carry-in / out station 20 is provided with a FOUP mounting table 30 on which a plurality of FOUPs F are placed. A wafer transfer device 40 is provided adjacent to the FOUP mounting table 30 on the positive side of the X-axis of the FOUP mounting table 30. The wafer transfer device 40 is configured to be movable on a transfer path 41 extending in the Y-axis direction. The wafer transfer device 40 has, for example, two transfer arms 42 that hold and transfer the overlapped wafer T. Each transfer arm 42 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 40 is configured to be able to transfer the overlapped wafer T between the FOUP F on the FOUP mounting table 30 and a transition device 50, which will be described later.

[0020] In the loading / unloading station 20 , a transition device 50 for transferring the overlapped wafer T between the processing station 21 and the wafer transfer device 40 is provided adjacent to the wafer transfer device 40 on the positive side of the X axis of the wafer transfer device 40 .

[0021] The processing station 21 is provided with a wafer transfer device 60, an edge removal device 70, a cleaning device 80, and a laser irradiation device 90. The wafer transfer device 60 is disposed on the X-axis positive side of the transition device 50. The edge removal device 70 and the laser irradiation device 90 are disposed on the Y-axis positive side of the wafer transfer device 60, and the cleaning device 80 and the laser irradiation device 90 are disposed on the Y-axis negative side of the wafer transfer device 60. The number and arrangement of the edge removal devices 70, cleaning devices 80, and laser irradiation devices 90 are not limited to those in this embodiment and can be determined as desired.

[0022] The wafer transfer device 60 is configured to be movable on a transfer path 61 extending in the X-axis direction. The wafer transfer device 60 also has, for example, two transfer arms 62 that hold and transfer the overlapped wafer T. Each transfer arm 62 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 60 is also configured to be able to transfer the overlapped wafer T to the transition device 50, edge removal device 70, cleaning device 80, and laser irradiation device 90 in the carry-in / out station 20.

[0023] The laser irradiation device 90 irradiates the inside of the first wafer W with a modifying laser beam (e.g., a YAG laser or a fiber laser) to form a modified peripheral layer that serves as a base point for peeling off the upper part of the peripheral edge We (hereinafter referred to as the "upper peripheral edge Wea"; see FIGS. 6 and 8 described below). The laser irradiation device 90 also has a control device 91 described below.

[0024] As shown in FIGS. 3 and 4 , the laser irradiation device 90 includes a chuck 100 that holds the overlapped wafer T on its upper surface. The chuck 100 holds the back surface Sb of the second wafer S by suction, with the first wafer W on top and the second wafer S on the bottom. The chuck 100 is supported by a slider table 102 via an air bearing 101. A rotation mechanism 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 by the rotation mechanism 103 via the air bearing 101. The slider table 102 is configured to be movable on rails 106 extending in the Y-axis direction on a base 105 via a movement mechanism 104 provided on its underside. The drive source of the movement mechanism 104 is not particularly limited, but may be, for example, a linear motor.

[0025] A laser head 110 for irradiating a laser beam generated by a laser oscillator (not shown) 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 laser beam onto the inside of the overlapped wafer T held by the chuck 100, more specifically, the inside of the first wafer W.

[0026] 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.

[0027] An imaging mechanism 120 is provided above the chuck 100 on the Y-axis positive side of the laser head 110. The imaging mechanism 120 includes at least one camera. An image captured by the camera is output to a control device 91 or a control device 280, which will be described later. The laser irradiation device 90 determines the position of the overlapped wafer T on the chuck 100 based on the image obtained by the imaging mechanism 120, and then aligns the overlapped wafer T and determines the irradiation position of the laser light based on this. The imaging mechanism 120 is configured to be able to move up and down freely by an elevating mechanism 121, and is further configured to be able to move freely in the Y-axis direction by a moving mechanism 122. The moving mechanism 122 is supported by a support column 116.

[0028] In the illustrated example, the chuck 100 is configured to be rotatable relative to the laser head 110 and movable horizontally 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 horizontally. Alternatively, both the chuck 100 and the laser head 110 may be configured to be rotatable relative to each other and movable horizontally.

[0029] 2 performs edge trimming, i.e., removal of the upper peripheral edge Wea of ​​the first wafer W, using the peripheral modified layer formed by the laser irradiation device 90 as a base point. Any method for removing the upper peripheral edge Wea can be selected. In one example, the edge removal device 70 may insert, for example, a wedge-shaped blade between the first wafer W and the second wafer S.

[0030] 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.

[0031] The second wafer processing system 12 has a configuration in which a carry-in / out station 200 and a processing station 201 are integrally connected. In the carry-in / out station 200, for example, a FOUP F capable of accommodating a plurality of overlapped wafers T is carried in and out between the outside. The processing station 201 is equipped with various processing devices that perform desired processing on the overlapped wafers T.

[0032] The carry-in / out station 200 is provided with a FOUP mounting table 210 on which a plurality of FOUPs F can be placed. A wafer transfer device 220 is provided adjacent to the FOUP mounting table 210 on the positive side of the X-axis. The wafer transfer device 220 is configured to be movable on a transfer path 221 extending in the Y-axis direction. The wafer transfer device 220 has, for example, two transfer arms 222 for holding and transferring the overlapped wafer T. Each transfer arm 222 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 220 is configured to be able to transfer the overlapped wafer T between the FOUP F on the FOUP mounting table 210 and a transition device 230, which will be described later.

[0033] In the loading / unloading station 200 , a transition device 230 for transferring the overlapped wafer T between the processing station 201 and the wafer transfer device 220 is provided adjacent to the wafer transfer device 220 on the positive side of the X axis of the wafer transfer device 220 .

[0034] The processing station 201 is provided with a wafer transfer device 240, an etching device 250, a cleaning device 260, and a grinding device 270. The wafer transfer device 240 is disposed on the X-axis positive side of the transition device 230. The etching device 250 and the cleaning device 260 are disposed in a stacked manner on the Y-axis positive side of the wafer transfer device 240. The grinding device 270 is disposed on the X-axis positive side of the wafer transfer device 240. Note that the number and arrangement of the etching devices 250, cleaning devices 260, and grinding devices 270 are not limited to those in this embodiment and can be determined as desired.

[0035] The wafer transfer device 240 has, for example, two transfer arms 241 that adsorb and hold the overlapped wafer T using an adsorption / holding surface (not shown) and transfer the overlapped wafer T. Each transfer arm 241 is supported by an articulated arm member 242 and is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 240 is configured to be able to transfer the overlapped wafer T to the transition device 230, the etching device 250, the cleaning device 260, and the grinding device 270.

[0036] The etching device 250 supplies an etching liquid to the back surface Wb of the first wafer W after it has been ground by the grinding device 270, and wet-etches the back surface Wb.

[0037] The cleaning device 260 performs a cleaning process on the first wafer W and the second wafer S after they have been ground by the grinding device 270. Any cleaning method can be selected.

[0038] The grinding device 270 has a rotary table 271. Four chucks 272 that suction-hold the overlapped wafer T are provided on the rotary table 271. The four chucks 272 can be moved to a transfer position A0 and processing positions A1 to A3 by the rotary table 271 rotating about a rotation center line 273. Furthermore, each of the four chucks 272 is configured to be rotatable about a vertical axis by a rotation mechanism (not shown).

[0039] At the transfer position A0, the overlapped wafer T is transferred by the wafer transfer device 240. At the processing position A1, a rough grinding unit 274 is disposed and performs rough grinding of the first wafer W. At the processing position A2, a medium grinding unit 275 is disposed and performs medium grinding of the first wafer W. At the processing position A3, a finish grinding unit 276 is disposed and performs finish grinding of the first wafer W. Note that at the transfer position A0, cleaning of the back surface Wb of the first wafer W may be further performed.

[0040] The above-described wafer processing system 10 is provided with a control device 91, at least one control device 280, and at least one control device 281. The control device 91 individually controls the operation of the laser irradiation device 90. The control device 280 controls the series of wafer processing in the first wafer processing system 11. The control device 281 controls the series of wafer processing in the second wafer processing system 12. Note that the control devices 280 and 281 may be controlled by a higher-level control device (not shown).

[0041] The controller 91 and the controllers 280-281 each process computer-executable instructions that cause the laser irradiation apparatus 90, the first wafer processing system 11, and the second wafer processing system 12 to perform the various steps described herein. The controller 91 and the controllers 280-281 can be configured to control the elements of the laser irradiation apparatus 90, the first wafer processing system 11, and the second wafer processing system 12, respectively, to perform the various steps described herein. In one embodiment, some or all of the controller 91 can be included in the laser irradiation apparatus 90, some or all of the controller 280 can be included in the first wafer processing system 11, and some or all of the controller 281 can be included in the second wafer processing system 12.

[0042] The control device 91 and the control devices 280-281 may each include a processing unit, a storage unit, and a communication interface. The control device 91 and the control devices 280-281 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 laser irradiation device 90 and the wafer processing system 10 via a communication line such as a LAN (Local Area Network).

[0043] In this embodiment, the control device 91 is installed separately from the laser irradiation device 90, but the control device 91 may be configured integrally with the control device 280. In other words, the operation of the laser irradiation device 90 may be controlled by the control device 280.

[0044] Next, a description will be given of wafer processing performed using the wafer processing system 10 configured as described above. In this embodiment, before processing in the wafer processing system 10, the first wafer W and the second wafer S are bonded together outside the wafer processing system 10 to form an overlapped wafer T. In this embodiment, the wafer processing includes a process of thinning the first wafer W of the overlapped wafer T.

[0045] First, in the first wafer processing system 11 , the FOUP F containing a plurality of overlapping wafers T is placed on the FOUP placement table 30 of the carry-in / out station 20 .

[0046] Next, the overlapped wafer T is removed from the FOUP F by the wafer transfer device 40 and transferred to the transition device 50. Subsequently, the overlapped wafer T is transferred to the laser irradiation device 90 by the wafer transfer device 60.

[0047] 6, the laser irradiation device 90 irradiates the inside of the first wafer W with a modifying laser beam L to form a first peripheral modified region N1, a second peripheral modified region N2, and a divided modified region N3. In this embodiment, the first peripheral modified region N1, the second peripheral modified region N2, and the divided modified region N3 are formed in this order (St to St3 in FIG. 5). Note that in FIG. 6 and the drawings used in the following description, the divided modified region N3 may be omitted to avoid complicating the illustration.

[0048] 6A , when forming the first peripheral modified region N1 in St1, laser light L is irradiated into the interior of the first wafer W along the radially inner side surface of the upper peripheral edge Wea to be removed by the peripheral edge removal device 70. When the first peripheral modified layer M1 is formed by this laser light L, a first crack C1 extends from the first peripheral modified layer M1 along the side surface of the upper peripheral edge Wea. Then, a first peripheral modified region N1 including the first peripheral modified layer M1 and the first crack C1 is formed.

[0049] The first peripheral modified region N1 is formed from bottom to top along the side of the upper peripheral edge Wea. That is, the laser light L is sequentially irradiated from bottom to top. Here, for example, if the first peripheral modified region N1 is formed from top to bottom, there is a risk that the first crack C1 will extend to the device layer Dw. In this regard, by forming the first peripheral modified region N1 from bottom to top, it is possible to prevent the first crack C1 from extending into the device layer Dw and prevent damage to the device layer Dw. As a result, the product yield can be improved.

[0050] The upper end of the first peripheral modified region N1 is the boundary between the peripheral portion We and the central portion Wc of the first wafer W. As shown in Fig. 7 , the upper end of the first peripheral modified region N1 is located radially inside the notch portion N of the first wafer W. The lower end of the first peripheral modified region N1 is located below the grinding surface G along which the grinding device 270 grinds the central portion Wc.

[0051] The first peripheral modified region N1 extends from the back surface Wb (upper) of the first wafer W to the front surface Wa (lower) thereof, inclining from the inner to the outer radial direction of the first wafer W, or the lower portion of the first peripheral modified region N1 is curved downward in a convex shape in side view. As will be described later, the second peripheral modified region N2 extends horizontally from the lower end of the first peripheral modified region N1 to the outer radial direction. The angle between the top portion Wep of the upper peripheral portion Wea formed by the first peripheral modified region N1 and the second peripheral modified region N2 (see FIG. 6 ) is an obtuse angle (90 degrees or greater).

[0052] For example, if the first peripheral modified region N1 is formed in the thickness direction and the angle between the top Wep of the upper peripheral Wea formed by the first peripheral modified region N1 and the second peripheral modified region N2 is a right angle, there is a risk that a portion of the upper peripheral Wea will remain at the top Wep when the upper peripheral Wea is removed as described below. In such a case, the remaining portion of the upper peripheral Wea may be chipped off and become particles. In this regard, by making the angle between the top Wep of the upper peripheral Wea formed by the first peripheral modified region N1 and the second peripheral modified region N2 an obtuse angle, as in the present embodiment, the load at the removal position during removal of the upper peripheral Wea is smaller than when the top Wep of the upper peripheral Wea is a right angle. This allows the upper peripheral Wea to be removed appropriately, thereby suppressing the generation of particles.

[0053] Furthermore, when the lower portion of the first peripheral modified region N1 has a curved shape that is convex downward in side view, the angle of the lower portion of the first peripheral modified region N1 from the horizontal increases from bottom to top. By curving the lower portion of the first peripheral modified region N1 in this manner, it is possible to prevent the first peripheral modified region N1 from extending radially inward. As a result, the radial distance of the first peripheral modified region N1 can be reduced.

[0054] 6(b), when forming the second peripheral modified layer M2 in St2, laser light L is irradiated into the interior of the first wafer W along the bottom surface of the upper peripheral edge Wea. When the second peripheral modified layer M2 is formed by this laser light L, a second crack C2 extends from the second peripheral modified layer M2 along the bottom surface of the upper peripheral edge Wea. Then, a second peripheral modified region N2 including the second peripheral modified layer M2 and the second crack C2 is formed.

[0055] The second peripheral modified layer M2 may be formed from the outside to the inside in the radial direction, or from the inside to the outside in the radial direction. In other words, the radial irradiation direction of the laser light is arbitrary.

[0056] The second peripheral modified layer M2 is formed by extending horizontally in a straight line radially outward from the lower end of the first peripheral modified region N1. In this embodiment, the first peripheral modified layer M1 at the lower end of the first peripheral modified region N1 is positioned at the intersection of the first peripheral modified region N1 and the second peripheral modified region N2. A crack that occurs between the second peripheral modified region N2 and the lower first peripheral modified layer M1 is connected to the second peripheral modified region N2. Specifically, the second crack C2 in the second peripheral modified region N2 is connected to the lower first peripheral modified layer M1. In this case, it is possible to prevent the crack from extending radially inward from the first peripheral modified region N1.

[0057] The second peripheral modified region N2 is formed to extend below the grinding surface G. The position of the second peripheral modified region N2 in the thickness direction is arbitrary, but is set so as to suppress chipping when the back surface Wb of the first wafer W is ground, as will be described later. Furthermore, the position of the second peripheral modified region N2 in the thickness direction is set so as not to expose the front surface Sa of the second wafer S when the back surface Wb of the first wafer W is etched, as will be described later. For example, the distance between the second peripheral modified region N2 and the device layer Dw is 5 μm to 10 μm shorter than the distance between the grinding surface G and the device layer Dw.

[0058] These first peripheral modified region N1 and second peripheral modified region N2 serve as base points for removing the upper peripheral Wea. The order of forming the first peripheral modified region N1 and the second peripheral modified region N2 is arbitrary, but it is preferable to form the first peripheral modified region N1 first and then the second peripheral modified region N2, as in this embodiment. In this case, the extension of the second crack C2 in the second peripheral modified region N2 connects to the first peripheral modified layer M1 at the lower end of the first peripheral modified region N1. This prevents the second crack C2 from forming radially inward from the first peripheral modified region N1, and therefore prevents the second crack C2 from remaining inside the first wafer W after grinding.

[0059] 6C and 7 , when forming the divided modified region N3 in St3, laser light L is irradiated radially outward from the first peripheral modified region N1. When the divided modified layer M3 is formed by this laser light L, a third crack C3 extends from the divided modified layer M3 along the thickness direction. Then, the divided modified region N3 including the divided modified layer M3 and the third crack C3 is formed.

[0060] The divided modified regions N3 are formed radially outward from the first peripheral modified region N1. The divided modified layers M3 serve as starting points for breaking the upper peripheral edge Wea into small pieces to be removed. That is, when the upper peripheral edge Wea is removed using the peripheral edge removal device 70, the upper peripheral edge Wea is peeled off from the first peripheral edge modified region N1 and the second peripheral edge modified region N2 as starting points, and is divided into multiple pieces by the radial divided modified regions N3. This makes the upper peripheral edge Wea to be removed smaller, making it easier to remove.

[0061] The positions of the divided modified regions N3 are not limited to the illustrated example. For example, the divided modified regions N3 may be formed in a plurality of rings in a planar view at any intervals concentrically with the first peripheral modified region N1. Furthermore, for example, the divided modified regions N3 may be formed in a spiral shape in a planar view radially outward of the first peripheral modified region N1.

[0062] In this embodiment, the divided modified region N3 is formed after the first peripheral modified region N1 and the second peripheral modified region N2 are formed, but the order of forming the divided modified region N3 is arbitrary. For example, the divided modified region N3 may be formed before the first peripheral modified region N1 and the second peripheral modified region N2 are formed.

[0063] The overlapped wafer T, in which the first peripheral modified region N1, the second peripheral modified region N2, and the divided modified region N3 have been formed inside the first wafer W, is then transferred by the wafer transfer device 60 to the peripheral removal device 70. In the peripheral removal device 70, a blade B is inserted between the first wafer W and the second wafer S, as shown in FIG. 8A, and the upper peripheral edge Wea is removed from the first wafer W (St4 in FIG. 5). At this time, the upper peripheral edge Wea is peeled and removed from the central portion We of the first wafer W, using the first peripheral modified region N1 and the second peripheral modified region N2 as base points. In addition, a lower peripheral edge Web remains on the peripheral edge We of the first wafer W below the grinding surface G.

[0064] Furthermore, as described above, the angle of the top Wep of the upper peripheral Wea formed by the first peripheral modified region N1 and the second peripheral modified region N2 is an obtuse angle, so when removing the upper peripheral Wea from the first wafer W, it is possible to prevent a portion of the upper peripheral Wea from remaining on the first wafer W.

[0065] The overlapped wafer T from which the upper peripheral edge Wea of ​​the first wafer W has been removed is then transferred by the wafer transfer device 60 to the cleaning device 80. In the cleaning device 80, the first wafer W and the second wafer S from which the upper peripheral edge Wea has been removed are cleaned (St5 in FIG. 5 ).

[0066] Next, the overlapped wafer T is transferred by the wafer transfer device 40 to the FOUP F on the FOUP mounting table 30 via the transition device 50. In this way, a series of processes in the first wafer processing system 11 is completed.

[0067] Next, in the second wafer processing system 12 , the FOUP F containing the multiple overlapping wafers T from which the upper peripheral edges Wea of ​​the first wafers W have been removed is placed on the FOUP placement table 210 of the transfer station 200 .

[0068] Next, the overlapped wafer T is removed from the FOUP F by the wafer transfer device 220 and transferred to the transition device 230. Subsequently, the overlapped wafer T is transferred to the grinding device 270 by the wafer transfer device 240.

[0069] In the grinding device 270, as shown in FIG. 8B, the back surface Wb of the central portion Wc of the first wafer W is ground to thin the central portion Wc down to the ground surface G (St6 in FIG. 5).

[0070] In St6, in the grinding device 270, the first wafer W is transferred to the chuck 272 at the delivery position A0, and then the rotary table 271 is rotated to move the chuck 272 sequentially to the processing positions A1 to A3. At the processing position A1, the rough grinding unit 274 rough-grinds the back surface Wb of the first wafer W. At the processing position A2, the medium grinding unit 275 medium-grinds the back surface Wb of the first wafer W. At the processing position A3, the finish grinding unit 276 finish-grinds the back surface Wb of the first wafer W. Once the first wafer W has been thinned to the desired thickness by the grinding process, the chuck 272 is then moved to the delivery position A0.

[0071] In St6, a lower peripheral edge Web remains on the peripheral portion We of the first wafer W, but the lower peripheral edge Web is located below the grinding surface G. Therefore, in rough grinding, medium grinding, and finish grinding of the back surface Wb of the first wafer W, the grinding wheels of the rough grinding unit 274, medium grinding unit 275, and finish grinding unit 276 do not come into contact with the lower peripheral edge Web, and chipping can be suppressed.

[0072] The overlapped wafer T, in which the first wafer W has been thinned, is then transferred by the wafer transfer device 240 to the cleaning device 260. In the cleaning device 260, the first wafer W and the second wafer S are cleaned (St7 in FIG. 5).

[0073] Next, the overlapped wafer T is transferred by the wafer transfer device 240 to the etching device 250. In the etching device 250, an etching solution is supplied to the entire back surface Wb of the first wafer W, as shown in FIG. 8C, and the central portion Wc and the lower peripheral edge Web are etched (St8 in FIG. 5). Then, the first wafer W (silicon) is entirely removed by etching.

[0074] In St8, because the lower peripheral Web remains in the peripheral portion We, the surface Sa of the second wafer S is not exposed, and damage to the surface Sa can be suppressed. Furthermore, because the thickness of the lower peripheral Web is smaller than the thickness of the central portion Wc, there is a possibility that the lower peripheral Web will be etched first, but as described above, the thickness of the lower peripheral Web (the position in the thickness direction of the second peripheral modified region N2) is set so that the surface Sa of the second wafer S is not exposed.

[0075] Next, the overlapped wafer T is transferred by the wafer transfer device 220 to the FOUP F on the FOUP mounting table 210 via the transition device 230. In this way, a series of processes in the second wafer processing system 12 is completed.

[0076] According to the above embodiment, when the upper peripheral edge Wea is removed in St4, the lower peripheral edge Web is left. Then, in St8, the entire back surface Wb of the first wafer W is etched while the lower peripheral edge Web remains. This prevents the front surface Sa of the second wafer S from being exposed, thereby preventing damage to the front surface Sa. Furthermore, since damage to the second wafer S can be prevented in this way, the second wafer S can be appropriately used, for example, even when multiple device layers Dw are stacked.

[0077] In this embodiment, in St6, the central portion Wc of the first wafer W is ground in a state in which the lower peripheral edge Web remains below the grinding surface G. Therefore, the grinding wheels of the rough grinding unit 274, the medium grinding unit 275, and the finish grinding unit 276 do not come into contact with the lower peripheral edge Web, thereby suppressing chipping.

[0078] In addition, in this embodiment, the angle of the top portion Wep of the upper peripheral edge Wea formed by the first peripheral modified region N1 and the second peripheral modified region N2 is an obtuse angle, which makes it possible to prevent a portion of the upper peripheral edge Wea from remaining on the first wafer W when removing the upper peripheral edge Wea from the first wafer W in St4. Furthermore, because the lower portion of the first peripheral modified region N1 is curved downward in a convex shape, the radial distance of the first peripheral modified region N1 can be reduced.

[0079] Here, as shown in FIG. 1, since the peripheral edge We of the first wafer W and the peripheral edge S of the second wafer S are each chamfered, an unbonded area where the first wafer W and the second wafer S are not bonded exists on the peripheral edge of the overlapped wafer T.

[0080] For example, when the base point for removing the upper peripheral edge Wea is a single inclined peripheral modified region that slopes from the inside to the outside in the radial direction of the first wafer W from the back surface Wb toward the front surface Wa of the first wafer W, if the lower end of the inclined peripheral modified region is located in an unbonded region, chipping may occur when grinding the back surface Wb of the first wafer W. Furthermore, if the lower end of the inclined peripheral modified region is located in a bonded region, a radially outer portion of the upper peripheral edge Wea may remain on the first wafer W when removing the upper peripheral edge Wea.

[0081] In this regard, according to the present embodiment, the first peripheral modified region N1 and the second peripheral modified region N2 are formed as base points for removing the upper peripheral weave, so that the upper peripheral weave can be appropriately removed. This can suppress chipping during grinding in St6 described above, and can also suppress the radially outer portion of the upper peripheral weave from remaining on the first wafer W when removing the upper peripheral weave in St4.

[0082] Furthermore, in this embodiment, in addition to the first peripheral modified region N1, a second peripheral modified region N2 is formed as a base point for removing the upper peripheral Wea, so that the upper peripheral Wea can be appropriately removed in St4 regardless of the structure of the device layer Dw.

[0083] The shape of the first peripheral modified region N1 is not limited to that of the above embodiment. For example, although the first peripheral modified region N1 in the above embodiment has a curved lower portion, the entire first peripheral modified region N1 may have a curved shape that is convex downward. Furthermore, for example, the first peripheral modified region N1 may have a linear shape that slopes from the inner radial direction to the outer radial direction of the first wafer W, from the back surface Wb to the front surface Wa of the first wafer W.

[0084] Furthermore, the shape of the second peripheral modified region N2 is not limited to that described in the above embodiment. For example, while the second peripheral modified region N2 in the above embodiment extends linearly horizontally in the radial direction, the second peripheral modified region N2 may have a linear shape that slopes downward from the radially inner side to the radially outer side, as shown in Figure 9. Furthermore, for example, the second peripheral modified region N2 may have a curved shape that curves downward in a convex manner in the radial direction.

[0085] Furthermore, although the second peripheral modified region N2 in the above embodiment is formed below the grinding surface G, the second peripheral modified region N2 may be formed at the same height as the grinding surface G. Furthermore, as shown in FIG. 10 , the second peripheral modified region N2 may be formed above the grinding surface G. Furthermore, the second peripheral modified region N2 may be formed so that its upper end is located above the grinding surface G and its lower end is located below the grinding surface G. However, in any of the three modified examples described above, when the back surface Wb of the first wafer W is ground in St5, the distance between the second peripheral modified region N2 and the device layer Dw needs to be sufficiently small to prevent chipping.

[0086] In addition, although the second crack C2 extends horizontally in the radial direction at the radially outer end of the second peripheral modified region N2 in the above embodiment, the second crack C2 may extend to the boundary between the unbonded region and the bonded region of the first wafer W and the second wafer S, as shown in Fig. 11. For example, when removing the upper peripheral edge Wea in St4, the second crack C2 may be extended to the boundary between the unbonded region and the bonded region of the first wafer W and the second wafer S by inserting a blade B between the first wafer W and the second wafer S.

[0087] Furthermore, in the above embodiment, the first peripheral modified layer M1 is located at the lower end of the first peripheral modified region N1 at the intersection between the first peripheral modified region N1 and the second peripheral modified region N2. However, the second peripheral modified layer M2 may be located at the radially inner end of the second peripheral modified region N2. In such a case, for example, the second peripheral modified region N2 may be formed first, followed by the first peripheral modified region N1. Furthermore, for example, a crack occurring between the first peripheral modified region N1 and the second peripheral modified layer M2 at the radially inner end may be connected. Specifically, the first crack C1 in the first peripheral modified region N1 may be connected to the second peripheral modified layer M2 at the radially inner end. In such a case, it is possible to prevent the crack from propagating radially inward (toward the device layer Dw) from the first peripheral modified region N1.

[0088] Furthermore, the timing for connecting the first peripheral modified region N1 and the second peripheral modified region N2, i.e., the timing for connecting the cracks, may be the timing for inserting blade B between the first wafer W and the second wafer S when removing the upper peripheral edge Wea in St4.

[0089] The positions and timings for forming the first cracks C1 and the second cracks C2 are controlled by optimizing the pulse energy (irradiation energy) and pulse pitch (irradiation interval) of the laser light L. For example, the pulse pitch is widened because stronger pulse energy makes it easier for the modified layers to connect.

[0090] In the above embodiment, when the back surface Wb of the first wafer W is etched in St8, the thickness of the lower peripheral edge Web is smaller than the thickness of the central portion We, and therefore the lower peripheral edge Web is etched first. In this regard, for example, the etching rate of the lower peripheral edge Web may be made smaller than the etching rate of the central portion We, so that the timing at which etching of the lower peripheral edge Web ends and the timing at which etching of the central portion We ends may be synchronized.

[0091] In the above embodiment, the upper peripheral edge Weak is removed in St4, and then the back surface Wb of the first wafer W is ground in St6. However, for example, the upper peripheral edge Weak may be removed while grinding the back surface Wb with the grinding device 270. For example, the upper peripheral edge Weak is blown away and removed by the impact when grinding the back surface Wb. In such a case, the peripheral edge removal device 70 may be omitted, and the grinding device 270 may also serve as the peripheral edge removal device.

[0092] Furthermore, in the above embodiments, before forming the first peripheral modified region N1, the second peripheral modified region N2, and the divided modified region N3 inside the first wafer W in St1 to St3, the back surface Wb of the first wafer W may be ground or etched to planarize the back surface Wb or to remove a thin film formed on the peripheral portion We. By grinding or etching the back surface Wb of the first wafer W to planarize it in this manner, it becomes easier to control the focus of the laser light L, and the first peripheral modified region N1, the second peripheral modified region N2, and the divided modified region N3 can be appropriately formed.

[0093] Furthermore, although the wafer processing system 10 in the above embodiment has the first wafer processing system 11 and the second wafer processing system 12, these first wafer processing system 11 and second wafer processing system 12 may be configured as an integrated system.

[0094] 12 , wafer processing system 300 has a configuration in which a load / unload station 310 and a processing station 311 are integrally connected. In load / unload station 310, for example, a FOUP F capable of accommodating a plurality of overlapped wafers T is loaded and unloaded between the load / unload station 310 and the outside. Processing station 311 is equipped with various processing devices that perform desired processing on overlapped wafers T.

[0095] The carry-in / out station 310 is provided with a FOUP mounting table 320 on which a plurality of FOUPs F can be placed. A wafer transfer device 330 is provided adjacent to the FOUP mounting table 320 on the positive side of the X-axis. The wafer transfer device 330 is configured to be movable on a transfer path 331 extending in the Y-axis direction. The wafer transfer device 330 also has, for example, two transfer arms 332 for holding and transferring the overlapped wafer T. Each transfer arm 332 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 330 is configured to be able to transfer the overlapped wafer T between the FOUP F on the FOUP mounting table 320 and a transition device 340, which will be described later.

[0096] In the loading / unloading station 310 , a transition device 340 for transferring the overlapped wafer T between the processing station 311 and the wafer transfer device 330 is provided adjacent to the wafer transfer device 330 on the positive side of the X axis of the wafer transfer device 330 .

[0097] The processing station 311 is provided with a wafer transfer device 350, an edge removal device 70, a cleaning device 80, a laser irradiation device 90, an etching device 250, a transition device 360, a wafer transfer device 370, and a grinding device 270. The edge removal device 70, the cleaning device 80, the laser irradiation device 90, the etching device 250, and the grinding device 270 each have the same configuration as the devices in the above embodiment.

[0098] The wafer transfer device 350 is disposed on the positive X-axis side of the transition device 340. The edge removal device 70 and the laser irradiation device 90 are disposed on the positive Y-axis side of the wafer transfer device 350, and the cleaning device 80 and the etching device 250 are disposed on the negative Y-axis side of the wafer transfer device 350. The number and arrangement of the edge removal device 70, cleaning device 80, laser irradiation device 90, and etching device 250 are not limited to those in this embodiment and can be determined as desired.

[0099] The wafer transfer device 350 is configured to be movable on a transfer path 351 extending in the X-axis direction. The wafer transfer device 350 also has, for example, two transfer arms 352 that hold and transfer the overlapped wafer T. Each transfer arm 352 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 350 is configured to be able to transfer the overlapped wafer T to the transition device 340, edge removal device 70, cleaning device 80, laser irradiation device 90, etching device 250, and transition device 360 ​​in the carry-in / out station 310.

[0100] The transition device 360 ​​is provided adjacent to the wafer transfer device 350 on the positive side of the X axis of the wafer transfer device 350. The transition device 360 ​​transfers the overlapped wafer T between the wafer transfer device 350 and the grinding device 270.

[0101] The wafer transfer device 370 is disposed on the negative Y-axis side of the transition device 360. The grinding device 270 is disposed on the positive X-axis side of the transition device 360.

[0102] The wafer transfer device 370 has, for example, two transfer arms 371 that adsorb and hold the overlapped wafer T using an adsorption / holding surface (not shown) and transfer the overlapped wafer T. Each transfer arm 371 is supported by an articulated arm member 372 and is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 370 is configured to be able to transfer the overlapped wafer T to the transition device 360 ​​and the grinding device 270.

[0103] The above wafer processing system 300 is provided with at least one controller 380. The configuration of the controller 380 is the same as that of the controllers 280 to 281 of the above embodiment.

[0104] In the wafer processing system 300 configured as described above, wafer processing is performed in the same manner as in the wafer processing system 10 of the above embodiment. That is, in the wafer processing system 300, the above-described St1 to St8 are performed sequentially. Note that in the wafer processing system 300, St5 can be omitted.

[0105] 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.

[0106] 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.

[0107] 10 Wafer processing system 70 Edge removal device 90 Laser irradiation device 250 Etching device 270 Grinding device 280 Control device N1 First edge modified region N2 Second edge modified region S Second wafer T Overlapped wafer W First wafer Wc Center Wea Upper edge Web Lower edge

Claims

1. A substrate processing method for processing an overlapped substrate formed by bonding a first substrate and a second substrate, comprising: forming a first peripheral modified region inside the first substrate along the side of the upper peripheral edge to be removed in the first substrate; forming a second peripheral modified region inside the first substrate along the bottom surface of the upper peripheral edge; removing the upper peripheral edge from the first substrate using the first peripheral modified region and the second peripheral modified region as base points, leaving a lower peripheral edge below the upper peripheral edge in the first substrate; grinding a central portion of the first substrate radially inward of the removed upper peripheral edge; and etching the entire surface of the first substrate from which the central portion has been ground, including the lower peripheral edge.

2. The substrate processing method according to claim 1, wherein the lowermost end of the second peripheral modified region is located below the grinding surface of the central portion.

3. A substrate processing method according to claim 1 or 2, wherein the first peripheral modified region extends from above to below the first substrate, sloping from the radially inner side to the radially outer side of the first substrate.

4. The substrate processing method according to claim 1 or 2, wherein at least a lower portion of the first peripheral modified region is curved in a side view.

5. The substrate processing method according to claim 1 or 2, wherein the second peripheral modified region is formed after the first peripheral modified region is formed.

6. The substrate processing method according to claim 5, wherein the first peripheral modified region is formed from below toward above, and then the second peripheral modified region is formed.

7. The substrate processing method according to claim 1 or 2, wherein the first peripheral modified region is formed after the second peripheral modified region is formed.

8. A substrate processing method as described in claim 1 or 2, wherein the first peripheral modified region includes a first peripheral modified layer and a first crack extending from the first peripheral modified layer, the second peripheral modified region includes a second peripheral modified layer and a second crack extending from the second peripheral modified layer, and either the first peripheral modified layer or the second peripheral modified layer is formed at the point where the first peripheral modified region and the second peripheral modified region intersect.

9. A substrate processing system for processing an overlapped substrate formed by bonding a first substrate and a second substrate, comprising: a laser irradiation device that irradiates the first substrate with laser light to form a modified region inside the first substrate; a peripheral removal device that removes an upper peripheral portion of the first substrate to be removed from the first substrate, using the modified region as a base point; a grinding device that grinds a central portion radially inward of the upper peripheral portion of the first substrate; an etching device that etches the entire surface of the first substrate from which the central portion has been ground; and a control device, wherein the control device: when irradiating the first substrate with the laser light to form the modified region inside the first substrate, controls to form a first peripheral modified region inside the first substrate along the side of the upper peripheral portion and to form a second peripheral modified region inside the first substrate along the bottom surface of the upper peripheral portion; and when removing the upper peripheral portion from the first substrate, controls to leave a lower peripheral portion of the first substrate below the upper peripheral portion. and performing control to etch the lower peripheral edge simultaneously when etching the entire surface of the first substrate.

10. The substrate processing system of claim 9, wherein the control device executes control to form the second peripheral modified region so that the lowest end of the second peripheral modified region is located below the grinding surface of the central portion.

11. A substrate processing system as described in claim 9 or 10, wherein the control device executes control to form the first peripheral modified region so that the first peripheral modified region extends from above to below the first substrate, sloping from the radially inner side to the radially outer side of the first substrate.

12. The substrate processing system according to claim 9 or 10, wherein the control device executes control to form the first peripheral modified region so that at least a lower portion of the first peripheral modified region is curved in a side view.

13. The substrate processing system according to claim 9 or 10, wherein the control device executes control to form the second peripheral modified region after forming the first peripheral modified region.

14. The substrate processing system according to claim 13, wherein the control device executes control to form the second peripheral modified region after forming the first peripheral modified region from below upward.

15. The substrate processing system according to claim 9 or 10, wherein the control device executes control to form the first peripheral modified region after forming the second peripheral modified region.

16. A substrate processing system as described in claim 9 or 10, wherein the first peripheral modified region includes a first peripheral modified layer and a first crack extending from the first peripheral modified layer, the second peripheral modified region includes a second peripheral modified layer and a second crack extending from the second peripheral modified layer, and the control device executes control to form either the first peripheral modified layer or the second peripheral modified layer at the intersection of the first peripheral modified region and the second peripheral modified region.

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