Processing method and processing system

Abstract

To appropriately remove the peripheral edge of a first substrate up to a bonding surface of the first substrate and a second substrate in a polymerized substrate in which the first substrate and the second substrate are bonded.SOLUTION: A processing method of a polymerized substrate includes: preparing a polymerized substrate in which a first substrate and a second substrate are bonded via a bonding layer, and a bonded region where the first substrate and the second substrate are bonded and an unbonded region where the first substrate and the second substrate are not in contact are formed at the interface of the first substrate and the second substrate; forming a peripheral edge modified layer that serves as a base point for peeling of the peripheral edge; removing the peripheral edge from the polymerized substrate; primary-thinning the first substrate; and removing an end portion of the first substrate after the primary-thinning by a desired radial width. When forming the peripheral modified layer, cracks extending from the peripheral modified layer are extended toward the boundary between the bonded region and the unbonded region at the interface, or toward the unbonded region.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for processing at least two stacked wafers. This method for processing stacked wafers includes the steps of thermocompression bonding a thermocompression sheet to the outer periphery of one wafer where a chamfered portion is formed, irradiating the inside of the outer periphery of the one wafer with a laser beam to form a modified layer, and expanding the thermocompression sheet to destroy the chamfered portion and remove the chamfered portion from the one wafer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-181890 Summary of the Invention [Problem to be solved by the invention]

[0004] The technique according to the present disclosure appropriately removes the peripheral edge of the first substrate up to the bonding surface between the first and second substrates in a laminated substrate in which the first and second substrates are bonded together. [Means for solving the problem]

[0005] One aspect of the present disclosure is a method for treating a laminated substrate in which a first substrate and a second substrate are bonded together, the method comprising the steps of: preparing the laminated substrate in which the first substrate and the second substrate are bonded together via a bonding layer, and in which a bonded region where the first substrate and the second substrate are bonded together and an unbonded region where the first substrate and the second substrate are not in contact are formed at the interface between the first substrate and the second substrate; and performing a process for removing the edge portion of the first substrate along the boundary between a peripheral portion of the first substrate to be removed and a central portion of the first substrate. The method includes forming a peripheral modification layer that serves as a base point, removing the peripheral portion from the overlapping substrate using the peripheral modification layer as a base point, performing a primary thinning of the first substrate, and removing the edge of the first substrate after the primary thinning to a desired radial width by ablation using laser light irradiation, wherein when the peripheral modification layer is formed, cracks extending from the peripheral modification layer are extended toward the boundary between the bonded region and the unbonded region at the interface, or toward the unbonded region. [Effects of the Invention]

[0006] According to the present disclosure, in a laminated substrate in which a first substrate and a second substrate are bonded together, the peripheral edge of the first substrate is appropriately removed up to the bonding surface between the first substrate and the second substrate. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a side view showing an example of the configuration of an overlapping wafer to be processed. [Figure 2] 2 is an enlarged view of a main part showing the peripheral portion of the overlapped wafer shown in FIG. 1. FIG. [Figure 3] 1 is a plan view showing an outline of the configuration of a wafer processing system according to an embodiment; [Figure 4] 10A and 10B are explanatory views showing the arrangement of modified layers formed on the overlapping wafer. [Figure 5] FIG. 2 is a flow chart showing main steps of wafer processing according to an embodiment. [Figure 6] 1A to 1C are explanatory views showing main steps of wafer processing according to an embodiment. [Figure 7]10A and 10B are explanatory views showing another example of forming a modified layer on the first wafer. [Figure 8] 10A and 10B are explanatory views showing another example of forming a modified layer on the first wafer. [Figure 9] FIG. 10 is an explanatory view showing another method for thinning the first wafer. [Figure 10] FIG. 10 is an explanatory view showing another method for thinning the first wafer. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the manufacturing process of semiconductor devices, a laminated substrate is formed by bonding a first substrate (a silicon substrate such as a semiconductor) having a device layer including multiple electronic circuits formed on its surface to a second substrate, and the peripheral portion of the first substrate may be removed, i.e., edge trimming may be performed.

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

[0010] The first and second substrates constituting the laminated substrate are usually bonded via a bonding film such as an oxide film. Therefore, even if a modified layer serving as a base point for edge trimming is formed inside the first substrate as disclosed in Patent Document 1, the bonded state of the peripheral edge of the removal target is maintained via the bonding film, which may result in insufficient removal of the peripheral edge of the first substrate.

[0011] The technology disclosed herein has been made in consideration of the above circumstances, and in a laminated substrate in which a first substrate and a second substrate are bonded, the peripheral portion of the first substrate is appropriately removed up to the bonding surface of the first substrate and the second substrate. Hereinafter, a wafer processing system as a processing system and a wafer processing method as a processing method according to this embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

[0012] In a wafer processing system 1 according to this embodiment, which will be described later, processing is performed on a laminated wafer T in which a first wafer W and a second wafer S are bonded together, as shown in FIG. 1 . A wafer is an example of a 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.

[0013] The first wafer W is a semiconductor wafer such as a silicon substrate, and has a device layer Dw including multiple devices formed on its surface Wa. A bonding film Fw (bonding layer) is further formed on the device layer Dw, and the first wafer S is bonded to the bonding film Fw. The bonding film Fw may be, for example, an oxide film (THOX film, SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive. The peripheral edge We of the first wafer W is chamfered, and the cross-section of the peripheral edge We becomes thinner toward its tip. The outer edge of the bonding film Fw has a rounded portion formed along the change in thickness associated with the chamfering of the first wafer W. The peripheral edge We is removed during edge trimming, which will be described later. It is defined as an annular region having a radial width extending from the outer edge of the first wafer W to a position slightly radially inward of a boundary Ad, which will be described later.

[0014] The second wafer S has, for example, the same configuration as the first wafer W, and has a device layer Ds and a bonding film Fs formed on its surface Sa, with its peripheral edge being chamfered. The outer edge of the bonding film Fs has a rounded portion. The second wafer S does not necessarily have to be a device wafer on which the device layer Ds is formed, but may also 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.

[0015] In the overlapped wafer T formed by bonding the first wafer W and the second wafer S in this manner, as shown in FIG. 2, the first wafer W and the second wafer S do not come into contact with each other at the chamfered portion (e.g., the rounded portion of the bonding films Fw and Fs) where the thickness is reduced at the peripheral edge, and therefore are not substantially bonded. In the following description, the unbonded portion corresponding to this chamfered portion (rounded portion) may be referred to as the "unbonded region Ae," the bonded portion radially inward of the unbonded region Ae as the "bonded region Ac," and the boundary between the unbonded region Ae and the bonded region Ac as the "boundary Ad" (see FIG. 2). As described above, in the edge trimming described below, the region extending slightly radially inward from the boundary Ad is considered to be the "periphery We" of the first wafer W according to the technology of the present disclosure, and is removed.

[0016] 3, wafer processing system 1 has a configuration in which a loading / unloading station 2 and a processing station 3 are integrally connected. In loading / unloading station 2, for example, a cassette C capable of accommodating a plurality of overlapped wafers T is loaded and unloaded between the loading / unloading station 2 and the outside. Processing station 3 is equipped with various processing devices that perform desired processing on overlapped wafers T.

[0017] The loading / unloading station 2 is provided with a cassette mounting table 10 on which a cassette C capable of accommodating a plurality of overlapped wafers T is mounted. A wafer transfer device 20 is provided adjacent to the cassette mounting table 10 on the positive side of the X-axis of the cassette mounting table 10. The wafer transfer device 20 moves on a transfer path 21 extending in the Y-axis direction, and is configured to be able to transfer the overlapped wafers T between the cassette C on the cassette mounting table 10 and a transition device 30, which will be described later.

[0018] In the loading / unloading station 2, a transition device 30 for transferring the overlapped wafer T to and from the processing station 3 is provided adjacent to the wafer transfer device 20 on the positive side of the X axis of the wafer transfer device 20.

[0019] In the processing station 3, a wafer transfer device 40, a modified layer forming device 50, a laser trimming device 60, an edge removing device 70, a cleaning device 80, and a processing device 90 are arranged.

[0020] The wafer transfer device 40 is provided on the positive X-axis side of the transition device 30. The wafer transfer device 40 is configured to be movable on a transfer path 41 extending in the X-axis direction, and is configured to be able to transfer the overlapped wafer T to the transition device 30, the modified layer forming device 50, the laser trimming device 60, the edge removing device 70, the cleaning device 80, and the processing device 90.

[0021] The modified layer forming device 50 irradiates the inside of the first wafer W with a first laser beam L1 (see FIG. 6(a)) in pulses to form a peripheral modified layer M1 that serves as a base point for peeling off the peripheral edge portion We, and divided modified layers M2 that serve as base points for dividing the peripheral edge portion We into small pieces, as shown in FIG. As the first laser beam L1, a laser beam having a wavelength that causes multiphoton absorption in the first wafer W, such as a fiber laser or a YAG laser, is selected. The modified layer forming apparatus 50 may also include a detection unit (not shown) for determining the irradiation position of the first laser light L1 on the overlapped wafer T (first wafer W). The detection unit may be, for example, an imaging mechanism (e.g., a camera) that images the outer edge of the overlapped wafer T on the substrate holding unit (not shown) from above, or may be, for example, a length measuring sensor (e.g., a displacement meter or an interferometer) that measures the distance to the outer edge of the overlapped wafer T on the substrate holding unit from the side.

[0022] The laser trimming device 60 irradiates the outer edge of the first wafer W after edge trimming in the edge removal device 70 (described later) with a second laser beam L2 (see FIG. 6(d)), and removes the edge portion We up to a predetermined trim width by ablation. The laser trimming device 60 also irradiates the overlapped wafer T after primary grinding in the processing device 90 (described later) with the second laser beam L2, and removes edge voids formed at the interface between the first wafer W and the second wafer S and debris adhering to the surface of the overlapped wafer T by ablation. For example, a femtosecond laser or a picosecond laser is selected as the second laser beam L2. The laser trimming device 60 may also include a detection unit (not shown) for determining the irradiation position of the second laser light L2 on the overlapped wafer T (first wafer W). The configuration of the detection unit is not particularly limited, and may be an imaging mechanism (e.g., a camera) or a length measuring sensor (e.g., a displacement meter or an interferometer), similar to the modified layer forming device 50.

[0023] The edge removal device 70 removes the edge portion We of the first wafer W, i.e., performs edge trimming, using the edge modified layer M1 formed by the modified layer forming device 50 as a base point. Any method for edge trimming can be selected. In one example, the edge removal device 70 may insert, for example, a wedge-shaped blade. 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.

[0024] The cleaning device 80 cleans the back surface Wb of the first wafer W, which is the processed surface that has been subjected to a grinding process in the processing device 90 described below. For example, a brush is brought into contact with the back surface Wb to scrub and clean the back surface Wb. A pressurized cleaning liquid may be used to clean the back surface Wb. The cleaning device 80 may also be configured to be able to simultaneously clean the back surface Sb of the second wafer S when cleaning the back surface Wb of the first wafer W. The cleaning device 80 may also further clean the back surface Wb of the first wafer W after the trimming process has been performed in the laser trimming device 60.

[0025] In the processing apparatus 90, the back surface Wb of the first wafer W after the removal (edge ​​trimming) of the peripheral edge We in the peripheral edge removal apparatus 70 is primarily ground, thereby thinning the first wafer W to a desired thickness. In addition, in the processing apparatus 90, the back surface Wb of the first wafer W after the trimming process in the laser trimming apparatus 60 is secondary ground, thereby thinning the first wafer W to a final finished thickness. As shown in FIG. 3 , the processing apparatus 90 has a rotary table 100, a primary grinding unit 110, and a secondary grinding unit 120.

[0026] The turntable 100 is configured to be rotatable about a vertical rotation center line 101 by a rotation mechanism (not shown). Four chucks 102 for suction-holding the overlapped wafer T are provided on the turntable 100. The chucks 102 are arranged evenly, i.e., at 90-degree intervals, on the same circumference as the turntable 100. The four chucks 102 can be moved to delivery positions A1, A2 and processing positions B1, B2 by the rotation of the turntable 100. Each chuck 102 is held by a chuck base (not shown) and configured to be rotatable by a rotation mechanism (not shown).

[0027] In this embodiment, the transfer position A1 is a position on the negative X-axis and negative Y-axis sides of the turntable 100, where the overlapped wafer T is transferred after edge trimming in the edge removal device 70. The transfer position A2 is a position on the negative X-axis and positive Y-axis sides of the turntable 100, where the overlapped wafer T is transferred after trimming in the laser trimming device 60. The processing position B1 is a position on the positive X-axis and positive Y-axis sides of the turntable 100, where the primary grinding unit 110 is located. The processing position B2 is a position on the positive X-axis and negative Y-axis sides of the turntable 100, where the secondary grinding unit 120 is located.

[0028] The primary grinding unit 110, which serves as a primary thinning device, grinds the back surface Wb of the first wafer W after the edge trimming in the edge removal device 70. The primary grinding unit 110 has a grinding section 111 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 111 is configured to be movable in the vertical direction along a support 112. Then, with the back surface Wb of the first wafer W held by the chuck 102 in contact with the grinding wheel, the chuck 102 and the grinding wheel are rotated, and the grinding wheel is lowered, thereby grinding the back surface Wb of the first wafer W. This reduces the thickness of the first wafer W to a preset thickness.

[0029] The secondary grinding unit 120, which serves as a secondary thinning device, grinds the back surface Wb of the first wafer W after the peripheral edge We has been removed by a predetermined trim width through trimming processing in the laser trimming device 60. The secondary grinding unit 120 has a grinding section 121 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 121 is configured to be movable vertically along a support 122. The back surface Wb of the first wafer W held by the chuck 102 is brought into contact with the grinding wheel, and the chuck 102 and the grinding wheel are rotated and further lowered to grind the back surface Wb of the first wafer W. This reduces the thickness of the first wafer W to a predetermined final thickness and flattens the back surface Wb of the first wafer W. In other words, the secondary grinding unit 120 can also be considered a unit for finish-grinding the back surface Wb of the first wafer W.

[0030] The wafer processing system 1 described above is provided with a control device 130. The control device 130 is, for example, a computer, and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the overlapped wafer T in the wafer processing system 1. The program storage unit also stores a program for controlling the operation of drive systems such as the various processing devices and transport devices described above to realize wafer processing, which will be described later, in the wafer processing system 1. The program may be recorded on a computer-readable storage medium H and installed from the storage medium H into the control device 130. The storage medium H may be temporary or non-temporary.

[0031] Next, a description will be given of wafer processing performed using the wafer processing system 1 configured as above. In this embodiment, the first wafer W and the second wafer S are bonded together to form an overlapping wafer T in advance.

[0032] First, a cassette C containing a plurality of overlapping wafers T is placed on the cassette mounting table 10 of the carry-in / out station 2. Next, the overlapping wafers T are removed from the cassette C by the wafer transfer device 20 and transferred to the modified layer forming device 50 via the transition device 30 and the wafer transfer device 40.

[0033] In the modified layer forming apparatus 50, first, the position of the overlapped wafer T held by a substrate holding unit (not shown), more specifically, the position of the outer edge of the first wafer W, is detected. The position of the outer edge of the first wafer W may be detected by, for example, capturing an image of the outer edge of the first wafer W in the 360-degree circumferential direction using an imaging mechanism as a detection unit, or may be detected by measuring the distance from a length measuring sensor as a detection unit to the outer edge of the first wafer W in the 360-degree circumferential direction. The detected position of the outer edge of the first wafer W is output to the control device 130.

[0034] The control device 130 determines the irradiation position of the first laser beam L1 on the first wafer W from the detected position of the outer edge of the first wafer W (step St1 in FIG. 5). In order to remove at least a part of the predetermined peripheral edge We to be removed, the irradiation position of the first laser beam L1 is determined to be a radial position that substantially coincides with the boundary Ad, which is the radially inner end (hereinafter referred to as the "inner end") of the unbonded region Ae shown in FIG. 2, or a radial position that corresponds to at least the unbonded region Ae radially outer than the boundary Ad. The formation width of the unbonded area Ae, which is the distance from the outer edge of the first wafer W to the boundary Ad, may be output from outside to the control device 130 when the overlapped wafer T is loaded into the wafer processing system 1, or if the detection unit is a length measuring sensor, it may be obtained using the length measuring sensor in the modified layer forming device 50.

[0035] Once the irradiation position of the first laser beam L1 has been determined, the first laser beam L1 is then irradiated in pulses onto the determined irradiation position to sequentially form a peripheral modified layer M1 and divided modified layers M2, as shown in FIGS. 4 and 6(a) (step St2 in FIG. 5). The peripheral modified layer M1 serves as a base point for removing the peripheral portion We in the edge trimming process described below. The divided modified layers M2 serve as base points for dividing the peripheral portion We into small pieces to be removed. Note that in the drawings used in the following explanation, the divided modified layers M2 may be omitted to avoid complicating the illustrations.

[0036] When the peripheral modified layer M1 is formed, a crack C1 (fissure) extends from the peripheral modified layer M1 inside the first wafer W in the thickness direction of the first wafer W. The upper end of the crack C1 extends, for example, toward the back surface Wb of the first wafer W, as shown in FIG. 6(a). The lower end of the crack C1 extends, for example, toward the inner end of the unbonded region Ae or toward the bonding surface (interface) between the first wafer W and the second wafer S in a portion corresponding to the unbonded region Ae. The extension direction of the crack C1 can be controlled, for example, by the irradiation conditions (irradiation position, output, etc.) of the first laser light L1.

[0037] The overlapped wafer T, in which the peripheral modified layer M1 and the divided modified layer M2 have been formed inside the first wafer W, is then transferred by the wafer transfer device 40 to the peripheral removal device 70. In the peripheral removal device 70, as shown in FIG. 6(b), at least a portion of the peripheral portion We of the first wafer W is removed, i.e., edge trimming is performed (step St3 in FIG. 5). To remove the peripheral portion We, a wedge-shaped blade B, for example, may be inserted into the interface between the first wafer W and the second wafer S that form the overlapped wafer T, as shown in FIG. 6(b).

[0038] At this time, the peripheral edge portion We is peeled from the center of the first wafer W (the radially inner side of the peripheral edge portion We) using the peripheral modified layer M1 as a base point, and is also broken into small pieces using the divided modified layer M2 as a base point. In this embodiment, the peripheral modified layer M1 is formed at a radial position that is approximately the same as the boundary Ad, which is the inner end of the unbonded region Ae, or at least radially outward of the boundary Ad. Furthermore, the lower ends of the cracks C1 extending from the peripheral modified layer M1 are caused to reach the inner end of the unbonded region Ae or at least the front surface Wa side of the first wafer W (the bonding surface side of the bonding film Fw to the second wafer S) of the portion corresponding to the unbonded region Ae. As a result, in this embodiment, the first wafer W and the second wafer S are not substantially bonded radially outward of the peripheral modified layer M1 (cracks C1), which includes at least a portion of the peripheral edge portion We to be removed. As a result, the peripheral edge portion We can be appropriately peeled from the second wafer S.

[0039] The overlapped wafer T, from which the peripheral edge portion We of the first wafer W has been removed, is then transferred by the wafer transfer device 40 to the processing device 90 and delivered to the chuck 102 at the delivery position A1. The chuck 102 suction-holds the back surface Sb of the second wafer S.

[0040] Next, the turntable 100 is rotated to move the overlapped wafer T to the processing position B1. At the processing position B1, with the back surface Wb of the first wafer W in contact with the grinding wheel of the primary grinding unit 110, the chuck 102 and the grinding wheel are rotated, and the grinding wheel is then lowered. This reduces the thickness of the first wafer W to a desired thickness, as shown in FIG. 6(c) (primary grinding: step St4 in FIG. 5). The thickness of the first wafer W after primary grinding is, for example, about 20 μm.

[0041] Next, the turntable 100 is rotated to move the overlapped wafer T to the delivery position A1. At the delivery position A1, the thickness of the first wafer W (overlapping wafer T) after the primary grinding may be measured by a thickness measuring means (not shown).

[0042] The overlapped wafer T, which has been subjected to the primary grinding of the first wafer W, is transferred by the wafer transfer device 40 to the cleaning device 80. In the cleaning device 80, the back surface Wb of the first wafer W after the primary grinding is cleaned. In the cleaning device 80, the back surface Sb of the second wafer S may also be cleaned.

[0043] The overlapped wafer T, whose rear surface Wb of the first wafer W has been cleaned, is then transferred by the wafer transfer device 40 to the laser trimming device 60.

[0044] In the laser trimming device 60, first, the position of the outer edge of the first wafer W after edge trimming is obtained. The position of the outer edge of the first wafer W may be detected by an imaging mechanism or a length measurement sensor. Alternatively, the irradiation position of the first laser light L1 set in step St1, i.e., the edge trim width of the peripheral portion We of the first wafer W, may be output to the control device 130, and the position of the outer edge of the first wafer W may be obtained from this trim width.

[0045] The control device 130 determines the irradiation area of ​​the second laser light L2 on the first wafer W from the acquired position of the outer edge of the first wafer W (step St5 in FIG. 5). The irradiation area of ​​the second laser light L2 is determined as an annular area extending from the detected outer edge of the first wafer W after edge trimming to the inner edge of the peripheral portion We, which is a predetermined trim width, as a reference.

[0046] Once the irradiation area of ​​the second laser beam L2 has been determined, the second laser beam L2 is then irradiated onto the determined irradiation area, and as shown in Fig. 6(d), the peripheral edge We remaining at the outer edge of the first wafer W up to a predetermined trim width is removed by ablation of the first wafer W (silicon) due to irradiation with the second laser beam L2 (step St6 in Fig. 5). According to this embodiment, the peripheral edge removal device 70 removes at least a portion of the peripheral edge We corresponding to the unbonded area Ae, and then performs this ablation removal (laser trimming process) after thinning the first wafer W by grinding. This reduces the amount of the outer edge of the first wafer W removed by ablation, and shortens the time required to remove the outer edge.

[0047] It should be noted that edge voids may occur at the bonding interface near the outer edges of the first wafer W and the second wafer S when the first wafer W and the second wafer S are bonded together.

[0048] Therefore, in the edge trimming process according to this embodiment, by removing the outer edge of the first wafer W with a predetermined trim width as shown in Fig. 6(d), it is possible to further remove edge voids formed at the bonding interface between the first wafer W and the second wafer S. As an example, it is preferable to set the removal width of the first wafer W by the second laser beam L2 to less than 50 µm from the boundary Ad shown in Fig. 2.

[0049] The overlapped wafer T, from which the peripheral edge We of the first wafer W has been removed by the laser trimming process, is then transferred by the wafer transfer device 40 to the cleaning device 80. In the cleaning device 80, the back surface Wb of the first wafer W after the laser trimming process is cleaned to remove debris and the like generated by ablation. In the cleaning device 80, the back surface Sb of the second wafer S may also be cleaned. Note that cleaning of the first wafer W after the laser trimming process may be omitted as appropriate.

[0050] The overlapped wafer T, whose back surface Wb of the first wafer W has been cleaned, is then transferred by the wafer transfer device 40 to the processing device 90 and delivered to the chuck 102 at the delivery position A2. The chuck 102 suction-holds the back surface Sb of the second wafer S.

[0051] Next, the turntable 100 is rotated to move the overlapped wafer T to the processing position B2. At the processing position B2, with the back surface Wb of the first wafer W in contact with the grinding wheel of the secondary grinding unit 120, the chuck 102 and the grinding wheel are rotated, and the grinding wheel is further lowered. As a result, the thickness of the first wafer W is reduced to the desired final thickness as shown in FIG. 6(e), and the back surface Wb of the first wafer W is flattened (secondary grinding: step St7 in FIG. 5).

[0052] Next, the turntable 100 is rotated to move the overlapped wafer T to the delivery position A2. At the delivery position A2, the thickness of the first wafer W (overlapping wafer T) after the secondary grinding may be measured by a thickness measuring means (not shown).

[0053] The overlapped wafer T, which has been subjected to the secondary grinding of the first wafer W, is transferred by the wafer transfer device 40 to the cleaning device 80. In the cleaning device 80, the back surface Wb of the first wafer W after the secondary grinding is cleaned. In the cleaning device 80, the back surface Sb of the second wafer S may also be cleaned.

[0054] Thereafter, the overlapped wafer T that has undergone all the processing is transferred by the wafer transfer device 40 to the transition device 30, and then transferred by the wafer transfer device 20 to the cassette C on the cassette mounting table 10. In this way, the series of wafer processing steps in the wafer processing system 1 is completed. After the secondary grinding of the first wafer W, the laminated wafer T, whose back surface Wb of the first wafer W has been cleaned, may be subjected to a wet etching process on the back surface Wb of the first wafer W using an etching device not shown.

[0055] According to the edge trimming technique of this embodiment, the modified layer forming apparatus 50 forms the peripheral modified layer M1 at a radial position that is approximately the same as the boundary Ad, which is the inner edge of the unbonded region Ae, or at least radially outward of the boundary Ad. At this time, the lower ends of the cracks C1 extending from the peripheral modified layer M1 are caused to reach the inner edge of the unbonded region Ae, or at least the front surface Wa side of the first wafer W (the bonding surface side of the bonding film Fw with the second wafer S) in a portion corresponding to the unbonded region Ae. This leaves the first wafer W and the second wafer S unbonded radially outward of the peripheral modified layer M1 (cracks C1), making it easy to peel at least a portion of the peripheral edge We to be removed from the second wafer S.

[0056] Furthermore, according to the edge trimming technique of this embodiment, the outer edge of the first wafer W after removal of the peripheral edge We in the peripheral edge removal device 70 is removed by ablation (laser trimming process) to a predetermined trim width. In this way, the trim width of the peripheral edge We of the first wafer W can be controlled by irradiation with the second laser light L2, and therefore, the trim width can be easily controlled precisely to a desired width.

[0057] Here, if the amount of removal of the outer edge of the first wafer W by ablation increases, for example, when the inner end of the desired trim width is set radially inward from the boundary Ad shown in FIG. 2, it may take a long time to remove the outer edge by ablation.

[0058] Therefore, in the edge trimming technique according to the embodiment, instead of vertically arranging the peripheral modified layers M1 so that their formation positions (irradiation positions of the first laser beam L1) correspond to the inner ends of the unbonded regions Ae or at least to radial positions corresponding to the unbonded regions Ae radially outward of the boundary Ad as shown in FIG. 6(a), the peripheral modified layers M1 may be arranged diagonally upward from the inner ends of the unbonded regions Ae toward the radially inward direction, as shown in FIG. 7. In this case, cracks C1 extend within the first wafer W to connect adjacent peripheral modified layers M1. Furthermore, the upper end of the crack C1 extends toward the back surface Wb of the first wafer W, and the lower end of the crack C1 extends toward the inner end of the unbonded region Ae, where the bonding strength is weak. By positioning the peripheral modification layer M1 at an angle in this manner, even when the trim width is large as described above, the amount of outer end removed by ablation in step St6 can be reduced, thereby suppressing a decrease in throughput related to edge trimming.

[0059] Also, for example, as shown in Figure 8, multiple peripheral modification layers M1 may be arranged vertically radially inward of the boundary Ad, and only the crack C1 formed from the lowest peripheral modification layer M1 may be extended diagonally toward the inner end of the unbonded area Ae.

[0060] In the above embodiment, after removing the peripheral portion We of the first wafer W, the first wafer W is thinned by primary grinding using the primary grinding unit 110 of the processing device 90, but the method of thinning the first wafer W is not limited to this. 9(a), in a modified layer forming apparatus 50, a first laser beam L1 may be irradiated along the surface direction inside a first wafer W to form an internal surface modified layer M3, and the first wafer W may be separated and thinned into a front surface Wa side and a back surface Wb side using this internal surface modified layer M3 as a base point, as shown in FIG. 9(b). The internal surface modified layer M3 remaining on the front surface Wa side of the first wafer W is removed in a subsequent secondary grinding (step St7). When the first wafer W is thinned by separation in this manner, the primary grinding unit 110 of the processing device 90 may be omitted from the configuration of the wafer processing system 1 shown in FIG.

[0061] Furthermore, when the first wafer W is thinned by separation in this manner, the rear surface Wb side and the peripheral edge portion We of the first wafer W may be removed integrally. Specifically, as shown in FIG. 10(a), in a modified layer forming apparatus 50, a first laser beam L1 is irradiated into the interior of a first wafer W to sequentially form a peripheral modified layer M1 and an internal surface modified layer M3. At this time, the end of a crack C3 (fissure) extending in the surface direction from the internal surface modified layer M3 reaches the uppermost peripheral modified layer M1 or the upper end of the crack C1. Then, by separating the first wafer W into a front surface Wa side and a back surface Wb side using the thus formed peripheral modified layer M1 and crack C1, and the internal surface modified layer M3 and crack C3 as base points, the peripheral portion We to be removed can be removed integrally with the back surface Wb side of the first wafer W, as shown in FIG. 10(b). When the peripheral edge We to be removed is removed integrally with the back surface Wb side of the first wafer W in this manner, the primary grinding unit 110 and peripheral edge removal device 70 of the processing device 90 may be omitted from the configuration of the wafer processing system 1 shown in Fig. 3. In other words, in the wafer processing system 1 according to the embodiment, the "primary thinning device" and the "periphery removal device" can be configured as an integrated unit.

[0062] In the above embodiment, after the second laser light L2 is irradiated onto the first wafer W, the first wafer W is thinned to a final finishing thickness using the secondary grinding unit 120 of the processing device 90, and the back surface Wb of the first wafer W is flattened, but the finishing method of the first wafer W is not limited to this. For example, the back surface Wb of the first wafer W may be finished (thinned and flattened to a final finish thickness) by etching instead of grinding by the secondary grinding unit 120. In this case, the wafer processing system 1 shown in FIG. 3 may include an etching device (not shown) instead of the secondary grinding unit 120 of the processing device 90. Further, for example, the back surface Wb of the first wafer W may be finished by polishing instead of grinding by the secondary grinding unit 120. In this case, in the wafer processing system 1 shown in FIG. 3, the secondary grinding unit 120 of the processing device 90 may be provided with a polishing member (not shown) instead of a grinding wheel. Alternatively, a polishing device (not shown) may be provided independently of the processing device 90.

[0063] In the above embodiment, the first wafer W after the primary grinding (step St4) and the secondary grinding (step St7) is transferred to the cleaning apparatus 80, and the back surface Wb is cleaned in the cleaning apparatus 80. However, the cleaning of the first wafer W after grinding may be performed using, for example, a cleaning unit (not shown) provided at the transfer positions A1 and A2 instead of the cleaning apparatus 80. In this case, the overlapped wafer T after the primary grinding (step St4) may be transferred to the laser trimming apparatus 60 without passing through the cleaning apparatus 80. Similarly, the overlapped wafer T after the secondary grinding (step St7) may be transferred to the cassette C on the cassette mounting table 10 without passing through the cleaning apparatus 80.

[0064] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0065] 1. Wafer Processing System 50 Modified layer forming device 60 Laser trimming device 70 Edge removal device 90 Processing equipment 110 Primary Grinding Unit 120 Secondary grinding unit 130 Control device Ac junction area Ad boundary Ae Unbonded area C1 Crack M1 Peripheral Modification Layer S Second wafer T Polymerized Wafer W First wafer We Periphery

Claims

1. A method for treating a laminated substrate in which a first substrate and a second substrate are bonded, comprising: preparing the laminated substrate in which the first substrate and the second substrate are bonded via a bonding layer, and a bonded region where the first substrate and the second substrate are bonded and an unbonded region where the first substrate and the second substrate are not in contact with each other are formed at the interface between the first substrate and the second substrate; forming a peripheral modified layer along the boundary between the peripheral portion of the first substrate to be removed and the central portion of the first substrate, the peripheral modified layer serving as a starting point for peeling off the peripheral portion; removing the peripheral portion from the laminated substrate starting from the peripheral modification layer; a first thinning of the first substrate; removing an edge portion of the first substrate after the primary thinning by ablation using laser light irradiation to a desired radial width; A processing method in which, when forming the peripheral modified layer, cracks extending from the peripheral modified layer are extended toward the boundary between the bonded region and the unbonded region at the interface, or toward the unbonded region.

2. The processing method of claim 1 , wherein the first substrate is primarily thinned by grinding.

3. forming an internal surface modification layer along a surface direction of the first substrate; The processing method of claim 1 , wherein the first substrate is primarily thinned by separating the first substrate starting from the internal surface modification layer.

4. The processing method according to claim 3 , wherein the removal of the peripheral portion and the primary thinning of the first substrate are performed simultaneously.

5. The method of any one of claims 1 to 4, further comprising a secondary thinning of the first substrate to a final finished thickness after the edge of the first substrate has been removed by ablation.

6. The processing method according to any one of claims 1 to 5, wherein the radial width of the first substrate removed by the ablation is less than 50 µm.

7. A processing system for processing a laminated substrate in which a first substrate and a second substrate are bonded together, comprising: the first substrate and the second substrate are bonded via a bonding layer; At the interface between the first substrate and the second substrate, a bonding region where the first substrate and the second substrate are bonded; a non-bonded region is formed where the first substrate and the second substrate are not in contact with each other; a modified layer forming device that forms a modified edge layer along the boundary between the peripheral edge of the first substrate to be removed and the central portion of the first substrate, the modified edge layer serving as a base point for peeling off the peripheral edge; a peripheral edge removal device that removes the peripheral portion from the laminated substrate, starting from the peripheral modified layer; a primary thinning device that primarily thins the first substrate; a laser trimming device that removes an edge of the first substrate after the primary thinning by ablation using irradiation with laser light to a desired radial width; a control device; The control device is a processing system that, when forming the peripheral modification layer, controls cracks extending from the peripheral modification layer to extend toward the boundary between the bonded region and the unbonded region at the interface, or toward the unbonded region.

8. The processing system according to claim 7 , wherein the primary thinning device comprises a grinding unit that thins the first substrate by grinding.

9. The control device Controlling the modified layer forming device to form an internal surface modified layer along a surface direction of the first substrate; 8. The processing system of claim 7, further comprising: a control for thinning the first substrate by separating the first substrate from the internal surface modification layer in the primary thinning device.

10. The control device When forming the internal surface modification layer, a control is performed to extend a crack extending from the internal surface modification layer toward the peripheral modification layer or a crack extending from the peripheral modification layer; The processing system of claim 9 , wherein the edge removal device is integral with the primary thinning device.

11. 11. The processing system according to claim 7, further comprising a secondary thinning device that thins the first substrate to a final finished thickness after the edge of the first substrate has been removed by the ablation.

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