Substrate processing apparatus and substrate processing method

Abstract

A substrate processing apparatus processes a superposed substrate in which a first substrate, an interface layer including at least a laser absorbing layer, and a second substrate are laminated. An outer peripheral region including a non-bonded region of the first substrate and the second substrate, and an inner peripheral region disposed radially inward of the outer peripheral region and a bonded region of the first substrate and the second substrate are set on the superposed substrate. A laser beam is irradiated on the overlapped substrate while moving in the radial direction, so that the interface between the first substrate and the laser absorbing layer or the interface between the interface layer and the laser absorbing layer is peeled off; and irradiating the laser beam at least in the outer peripheral region while moving the laser beam from the inside toward the outside in the radial direction.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing device and a substrate processing method. Background Art

[0002] Patent document 1 discloses that: in a semiconductor substrate having a peeling oxide film and a semiconductor element formed on the surface, the semiconductor element is transferred to a transfer destination substrate. The method described in Patent document 1 includes the following steps: irradiating light from the back side of the semiconductor substrate to locally heat the peeling oxide film; and causing peeling in the peeling oxide film and / or at the interface between the peeling oxide film and the semiconductor substrate to transfer the semiconductor element to the transfer destination substrate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-220749 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The technology according to the present disclosure appropriately performs separation of a first substrate and a laser absorption layer in a superimposed substrate in which a laser absorption layer is formed at an interface between a first substrate and a second substrate.

[0008] Solutions for solving problems

[0009] One embodiment of the present disclosure is a substrate processing device for processing a superimposed substrate formed by stacking a first substrate, an interface layer including at least a laser absorption layer, and a second substrate, the substrate processing device comprising: a substrate holding portion for holding the superimposed substrate; a laser irradiation portion for irradiating a laser beam to the superimposed substrate held by the substrate holding portion; a moving mechanism for moving the substrate holding portion and the laser irradiation portion relative to each other in a horizontal direction; a rotating mechanism for rotating the substrate holding portion; and a control portion, wherein an outer peripheral region including an unbonded region between the first substrate and the second substrate and an inner peripheral region which is arranged radially inward of the outer peripheral region and is a bonding region between the first substrate and the second substrate is set in the superimposed substrate, and the control portion performs the following control: rotating the superimposed substrate and irradiating the superimposed substrate with the laser beam while moving the superimposed substrate in a radial direction to generate peeling at an interface between the first substrate and the laser absorption layer or at an interface between the interface layer and the laser absorption layer; and irradiating at least in the outer peripheral region while moving the laser beam from the radial inside toward the outside.

[0010] Effects of the Invention

[0011] According to the present disclosure, in a superimposed substrate in which the laser absorption layer is formed at the interface between the first substrate and the second substrate, the first substrate and the laser absorption layer can be appropriately peeled off. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a side view showing a structural example of a superimposed wafer according to the embodiment.

[0013] Figure 2 FIG. 1 is a plan view schematically showing the structure of a wafer processing system.

[0014] Figure 3 It is a plan view schematically showing the structure of the laser irradiation device.

[0015] Figure 4 It is a side view showing an outline of the structure of the laser irradiation device.

[0016] Figure 5 It is a side view showing the operation of the separation device.

[0017] Figure 6 It is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam.

[0018] Figure 7 1 is a flowchart showing main steps of wafer processing in the wafer processing system.

[0019] Figure 8 It is an explanatory diagram showing the diffusion of heat generated in overlapping wafers.

[0020] Fig. 9 It is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam.

[0021] Fig.10 It is an explanatory diagram showing a state where the first wafer and the laser absorption layer are separated.

[0022] Fig.11 It is an explanatory diagram showing a state where the first wafer and the laser absorption layer are separated.

[0023] Fig.12 1 is a flowchart showing main steps of wafer processing in the wafer processing system.

[0024] Fig.13 It is an explanatory diagram showing the regions of the overlapping wafers, the rotation speed of the holding plate in each region, and the frequency of the laser beam in each region.

[0025] Fig.14 is a side view showing the outer peripheral area and the first inner peripheral area.

[0026] Fig.15It is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam in the outer peripheral region.

[0027] Fig.16 It is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam in the outer peripheral region.

[0028] Fig.17 It is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam in the outer peripheral region.

[0029] Fig.18 This is an explanatory diagram showing a state of overlapping wafers in which the second inner peripheral region and the first inner peripheral region are irradiated with a laser beam.

[0030] Fig.19 This is an explanatory diagram showing a state where the first inner peripheral region of the overlapped wafers is irradiated with a laser beam.

[0031] Fig. 20 It is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam at the center region.

[0032] Fig.21 This is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam in another embodiment.

[0033] Fig. 22 This is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam in another embodiment.

[0034] Fig.23 This is an explanatory diagram showing a state where overlapping wafers are irradiated with a laser beam in another embodiment.

[0035] Fig.24 It is an explanatory diagram showing a state where the peeling-promoting layer and the laser absorption layer are peeled off.

[0036] Fig.25 It is a flowchart showing main steps of wafer processing according to another embodiment. DETAILED DESCRIPTION

[0037] In the manufacturing process of semiconductor devices, in a superposed wafer formed by bonding two semiconductor substrates (hereinafter referred to as "wafers"), a device layer formed on the surface of a first wafer is transferred to a second wafer. The transfer of the device layer to the second wafer is performed by irradiating a laser beam to a laser absorption layer formed between the first wafer and the device layer to separate the first wafer from the laser absorption layer. Specifically, for example, the superposed wafer is rotated, and the laser beam is irradiated to the laser absorption layer in a pulsed state while the laser beam is moved from the radial outside to the inside.

[0038] Here, the peripheral portion of the overlapping wafer has a chamfered portion (bevel portion) formed by chamfering, and the peripheral portion is not bonded. That is, the peripheral area of ​​the overlapping wafer includes an unbonded area, and at the boundary between the unbonded area and the bonded area, the bonding strength of the interface between the first wafer (including the device layer) and the second wafer is low. In this case, when the laser beam is irradiated to the peripheral area, peeling occurs at the interface between the first wafer and the second wafer with low bonding strength in the peripheral area.

[0039] In this state, if the laser beam is irradiated while moving from the radially outer side to the inner side in the peripheral area, the peeling is likely to proceed with the interface between the first wafer and the second wafer where the peeling occurs as the front end in the bonding area adjacent to the radially inner side of the unbonded area. That is, in the bonding area of ​​the peripheral area, the peeling does not occur at the interface between the first wafer and the laser absorption layer as the desired interface. In this way, the device layer of the first wafer cannot be transferred to the second wafer.

[0040] The technology disclosed herein appropriately performs the peeling of the first substrate and the laser absorption layer in a superimposed substrate in which the laser absorption layer is formed at the interface between the first substrate and the second substrate. Hereinafter, a wafer processing system having a laser irradiation device as a substrate processing device according to the present embodiment and a wafer processing method as a substrate processing method are described with reference to the accompanying drawings. In addition, in this specification and the accompanying drawings, the same reference numerals are given to elements having substantially the same functional structure, thereby omitting repeated descriptions.

[0041] In the wafer processing system 1 described later according to this embodiment, Figure 1 The superimposed wafer T as a superimposed substrate formed by bonding the first wafer W and the second wafer S is processed. In the following, in the first wafer W, the surface on the side bonded to the second wafer S is referred to as the surface Wa, and the surface on the side opposite to the surface Wa is referred to as the back side Wb. Similarly, in the second wafer S, the surface on the side bonded to the first wafer W is referred to as the surface Sa, and the surface on the side opposite to the surface Sa is referred to as the back side Sb.

[0042] The first wafer W as the first substrate is, for example, a semiconductor wafer such as a silicon substrate. In one embodiment, the first wafer W has a roughly circular plate shape. A stacked film formed by stacking a plurality of films is formed on the surface Wa of the first wafer W. The stacked film includes a laser absorption layer P, a device layer Dw, and a surface film Fw in sequence from the surface Wa side. The device layer Dw includes a plurality of devices. As the surface film Fw, for example, an oxide film (THOX film, SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive can be cited. The first wafer W is bonded to the second wafer S through the surface film Fw. In addition, the device layer Dw and the surface film Fw are sometimes not formed on the surface Wa. In this case, the laser absorption layer P is formed on the second wafer S side, and the device layer Ds on the second wafer S side described later is transferred to the first wafer W side.

[0043] The laser absorption layer P absorbs the laser beam irradiated from the laser irradiation unit 110 as described later. The laser absorption layer P uses, for example, an oxide film (SiO2 film, TEOS film), but is not particularly limited as long as it absorbs the laser beam. The laser absorption layer P is formed, for example, by a CVD (Chemical Vapor Deposition) process outside the wafer processing system 1 described later. The composition of the oxide film (SiO2 film, TEOS film) as the laser absorption layer P can be arbitrarily changed according to the type and mixing ratio of the processing gas used in the CVD process.

[0044] The second wafer S as the second substrate is, for example, a semiconductor wafer such as a silicon substrate. A laminated film is formed on the surface Sa of the second wafer S. The laminated film has a device layer Ds and a surface film Fs in sequence from the surface Sa side. The device layer Ds and the surface film Fs are respectively the same as the device layer Dw and the surface film Fw of the first wafer W. Moreover, the surface film Fw of the first wafer W is bonded to the surface film Fs of the second wafer S. In addition, sometimes the device layer Ds and the surface film Fs are not formed on the surface Sa.

[0045] In addition, in the technology disclosed herein, the laminated film formed at the interface between the first wafer W and the second wafer S, specifically the laser absorption layer P, the device layers Dw, Ds, and the surface films Fw, Fs are sometimes collectively referred to as an "interface layer". In the technology disclosed herein, the interface layer includes at least the laser absorption layer P.

[0046] In addition, the type of the laminated film formed at the interface between the first wafer W and the second wafer S is not limited to Figure 1 For example, the laminated film may include a "peeling-promoting film" described later for appropriately peeling the first wafer W and the laser absorption layer P. In this case, the above-mentioned interface layer includes the peeling-promoting film.

[0047] like Figure 2As shown, the wafer processing system 1 has a structure in which a loading and unloading block 10, a conveying block 20, and a processing block 30 are integrally connected. The loading and unloading block 10 and the processing block 30 are arranged around the conveying block 20. Specifically, the loading and unloading block 10 is arranged on the negative direction side of the Y axis of the conveying block 20. The laser irradiation device 31 and the separation device 32 described later of the processing block 30 are arranged on the negative direction side of the X axis of the conveying block 20, and the first cleaning device 33 and the second cleaning device 34 described later are arranged on the positive direction side of the X axis of the conveying block 20.

[0048] The loading and unloading block 10 is used, for example, to load and unload boxes Ct, Cw, and Cs that can accommodate multiple overlapping wafers T, multiple first wafers W, and multiple second wafers S, respectively, between the outside. A box mounting table 11 is provided on the loading and unloading block 10. In the example shown in the figure, a plurality of, for example, three boxes Ct, Cw, and Cs can be mounted in a row along the X-axis direction on the box mounting table 11. In addition, the number of boxes Ct, Cw, and Cs mounted on the box mounting table 11 is not limited to the present embodiment and can be determined arbitrarily.

[0049] A wafer conveying device 22 is provided on the conveying block 20, and the wafer conveying device 22 is configured to be movable on a conveying path 21 extending in the X-axis direction. The wafer conveying device 22 has, for example, two conveying arms 23, 23 for holding and conveying overlapping wafers T, first wafers W, or second wafers S. Each conveying arm 23 is configured to be movable in a horizontal direction, a vertical direction, and around a horizontal axis and a vertical axis. In addition, the structure of the conveying arm 23 is not limited to the present embodiment, and any structure can be adopted. Moreover, the wafer conveying device 22 is configured to be able to convey overlapping wafers T, first wafers W, and second wafers S to the boxes Ct, Cw, Cs of the box mounting table 11, the laser irradiation device 31, the separation device 32, the first cleaning device 33, and the second cleaning device 34.

[0050] The processing block 30 includes a laser irradiation device 31, a separation device 32, a first cleaning device 33, and a second cleaning device 34. In one example, the laser irradiation device 31 and the separation device 32 are stacked on the negative side of the X axis of the conveying block 20. In addition, the first cleaning device 33 and the second cleaning device 34 are stacked on the positive side of the X axis of the conveying block 20. In addition, the number and arrangement of the laser irradiation device 31, the separation device 32, the first cleaning device 33, and the second cleaning device 34 are not limited thereto.

[0051] The laser irradiation device 31 irradiates the interior of the superimposed wafer T, more specifically, the laser absorption layer P formed on the surface Wa of the first wafer W, with a laser beam to reduce the bonding strength at the interface between the first wafer W and the laser absorption layer P.

[0052] like Figure 3As shown, a handover position A1 and a processing position A2 are set inside the laser irradiation device 31. The handover position A1 is a position where the overlapped wafer T can be handed over from the transfer arm 23 to the holding plate 100 described later, and is a position where the overlapped wafer T (laser absorption layer P) can be photographed by the camera 120 described later. The processing position A2 is a position where a laser beam can be irradiated from the laser irradiation unit 110 described later to the overlapped wafer T (laser absorption layer P).

[0053] like Figure 3 and Figure 4 As shown, the laser irradiation device 31 has a holding disk 100 as a substrate holding portion for holding the overlapping wafer T through the upper surface. The holding disk 100 has a holding surface for the overlapping wafer T on the upper surface, and adsorbs and holds the entire surface of the back side Sb of the second wafer S or a portion of the radial inner side of the back side Sb. The holding disk 100 is, for example, an electrostatic holding disk (ESC: Electrostatic Chuck) or a vacuum holding disk (Vacuum Chuck). The holding disk 100 is provided with lifting pins (not shown) for supporting the overlapping wafer T from below and lifting the overlapping wafer T. The lifting pins are configured to be inserted into a through hole (not shown) formed through the holding disk 100 and can be lifted and lowered.

[0054] The holding disk 100 is supported on the slide table 102 by the air bearing 101. A rotating mechanism 103 is provided on the lower surface side of the slide table 102. The rotating mechanism 103 has, for example, a motor built in as a driving source. The holding disk 100 is configured to be rotatable around the θ axis (vertical axis) by the rotating mechanism 103 through the air bearing 101. The slide table 102 is configured to be movable between the above-mentioned handover position A1 and the processing position A2 along a guide rail 106 provided on a base 105 and extending in the Y-axis direction by a moving mechanism 104 provided on the lower surface side thereof. In addition, the driving source of the moving mechanism 104 is not particularly limited, and, for example, a linear motor is used.

[0055] A laser irradiation unit 110 is provided above the holding disk 100 at the processing position A2. The laser irradiation unit 110 includes a laser head 111, an optical system 112, and a lens 113. The laser irradiation unit 110 can scan a laser beam. In the following description, scanning a laser beam means moving the laser beam irradiated from the lens 113 of the laser irradiation unit 110 relative to the laser absorption layer P.

[0056] The laser head 111 has a laser oscillator (not shown) that oscillates a laser beam in a pulsed state. The laser beam is a so-called pulsed laser. In addition, in the present embodiment, the laser beam is a CO2 laser beam, and the wavelength of the CO2 laser beam is, for example, 8.9 μm to 11 μm. In addition, the laser head 111 may also have other devices besides the laser oscillator, such as an amplifier.

[0057] The optical system 112 includes an optical element (not shown) for controlling the intensity and position of the laser beam, an attenuator (not shown) for attenuating the laser beam to adjust the output, and a laser scanning unit (not shown) for scanning the laser beam. The laser scanning unit uses, for example, a rotating wedge scanner or a galvanometer scanner. In addition, the optical system 112 may be configured to control the branching of the laser beam.

[0058] The lens 113 irradiates the laser beam to the overlapped wafer T held on the holding plate 100. The laser beam emitted from the laser irradiation unit 110 passes through the first wafer W and irradiates the laser absorption layer P. The lens 113 may be configured to be movable in the horizontal direction by a moving mechanism (not shown) or to be movable in the vertical direction by a lifting mechanism (not shown).

[0059] In addition, a camera 120 is provided above the holding disk 100 at the handover position A1. The camera 120 includes one or more cameras selected from a macro camera, a micro camera (Japanese: マイクロカメラ), etc. In addition, the camera 120 may be configured to be movable in the horizontal direction by a moving mechanism (not shown), or may be configured to be movable in the vertical direction by a lifting mechanism (not shown).

[0060] The camera 120 captures an image of the overlapped wafers T held on the holding plate 100. The camera 120 includes, for example, a coaxial lens, irradiates infrared light (IR), and receives reflected light from an object. Image data captured by the camera 120 is output to the control device 40 described later.

[0061] Furthermore, as will be described later, the wafer processing system 1 includes a control device 40 which is provided in the laser irradiation device 31 and functions also as a control unit for controlling the laser irradiation device 31 .

[0062] The separating device 32 as a separating unit separates the first wafer W from the second wafer S (overlapping wafer T) with the interface between the first wafer W and the laser absorption layer P as a separation portion having bonding strength reduced by the laser irradiation device 31 as a base point.

[0063] In one example, Figure 5As shown, the separation device 32 includes an adsorption holding plate 200 for adsorbing and holding the back side Sb of the second wafer S from below and an adsorption pad 210 for adsorbing and holding the back side Wb of the first wafer W from above. Figure 5 As shown, in a state where the suction holding plate 200 suction-holds the second wafer S and the suction pad 210 suction-holds the first wafer W, the suction pad 210 is raised to peel the first wafer W from the laser absorption layer P.

[0064] In addition, the structure of the separation device 32 is not limited to this, and any structure can be adopted as long as the first wafer W can be separated from the second wafer S.

[0065] The first cleaning device 33 cleans the surface Sa side of the second wafer S separated by the peeling performed by the separation device 32. For example, a brush is brought into contact with the laser absorption layer P on the surface Sa side of the second wafer S to clean the laser absorption layer P. In addition, a pressurized cleaning liquid may be used to clean the second wafer S. In addition, the first cleaning device 33 may also have a structure that cleans the back side Sb of the second wafer S together with the surface Sa side.

[0066] The second cleaning device 34 cleans the surface Wa side of the first wafer W separated by the peeling performed by the separation device 32. For example, a brush is brought into contact with the surface Wa of the first wafer W to clean the surface Wa. In addition, a pressurized cleaning liquid may be used to clean the first wafer W. In addition, the second cleaning device 34 may also have a structure that cleans the back side Wb of the first wafer W together with the surface Wa side.

[0067] In addition, in the present embodiment, as described above, the first cleaning device 33 for cleaning the second wafer S and the second cleaning device 34 for cleaning the first wafer W are independently configured, but the cleaning of the first wafer W and the cleaning of the second wafer S may also be performed using the same cleaning device. In this case, the cleaning of the first wafer W and the second wafer S may be performed simultaneously or independently.

[0068] In addition, in the present embodiment, the first wafer W is peeled off from the second wafer S using the separation device 32, but the peeling may be performed inside the laser irradiation device 31. For example, a transfer pad (not shown) that can be raised and lowered is provided at the handover position A1 of the laser irradiation device 31. Then, in a state where the holding plate 100 holds the second wafer S by suction, the first wafer W is held by the transfer pad and the transfer pad is raised, thereby peeling the first wafer W from the second wafer S.

[0069] The above wafer processing system 1 is provided with a control device 40 as a control unit. The control device 40 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 overlapping wafers T in the wafer processing system 1. In addition, the program storage unit also stores a program for controlling the operation of the drive system of the various processing devices, conveying devices, etc. mentioned above to realize the wafer processing described later in the wafer processing system 1. In addition, the above program can also be recorded in a computer-readable storage medium H, and installed from the storage medium H to the control device 40. In addition, the above storage medium H can be transient or non-transient.

[0070] Next, wafer processing using the wafer processing system 1 configured as above will be described. In the present embodiment, the first wafer W and the second wafer S are bonded to form a superimposed wafer T in advance in a bonding device (not shown) outside the wafer processing system 1 .

[0071] First, the cassette Ct storing a plurality of superimposed wafers T is placed on the cassette mounting table 11 of the loading / unloading block 10 .

[0072] Next, the wafer transfer device 22 takes out the overlapped wafer T in the cassette Ct and transfers it to the laser irradiation device 31. In the laser irradiation device 31, the overlapped wafer T is transferred to the holding plate 100 disposed at the transfer position A1 by the transfer arm 23, and the back side Sb of the second wafer S is sucked and held by the holding plate 100. Next, the moving mechanism 104 moves the holding plate 100 to the processing position A2.

[0073] Then, if Figure 6 As shown, the laser irradiation unit 110 focuses on the laser absorption layer P, more specifically, the interface between the first wafer W and the laser absorption layer P, to irradiate the interface with a laser beam L (CO2 laser beam) in a pulsed state. At this time, the laser beam L passes through the first wafer W from the back side Wb of the first wafer W and is absorbed at the laser absorption layer P. Moreover, the bonding strength between the first wafer W and the laser absorption layer P is reduced by the laser beam L. In addition, in the embodiment, "reduced bonding strength" refers to a state in which the bonding strength is reduced at least compared to before the laser beam L is irradiated, including the peeling of the first wafer W and the laser absorption layer P.

[0074] Note that the details of the mechanism of reduction in the bonding strength between the first wafer W and the laser absorption layer P due to irradiation with the laser beam L will be described later.

[0075] When the laser beam L is irradiated to the laser absorption layer P at the processing position A2, first, the overlapped wafer T (first wafer W) is photographed by the camera 120. The image data obtained by the camera 120 is output to the control device 40. In the control device 40, the irradiation start position of the laser beam L to the laser absorption layer P is determined based on the image data.

[0076] Next, at the processing position A2, the laser beam L is irradiated from the laser irradiation unit 110 to the entire surface of the laser absorption layer P in a top view at a desired interval to reduce the bonding strength of the entire surface of the interface between the first wafer W and the laser absorption layer P. Details of the method of irradiating the laser absorption layer P with the laser beam L will be described later.

[0077] When the entire surface of the laser absorption layer P is irradiated with the laser beam L and the bonding strength between the first wafer W and the laser absorption layer P is reduced, the holding plate 100 (overlapping wafer T) is then moved to the transfer position A1 by the moving mechanism 104 .

[0078] Next, the overlapped wafers T on the holding tray 100 are transferred to the transfer arm 23 of the wafer transfer device 22 and transferred to the separation device 32. In the separation device 32, as shown in FIG. Figure 5 As shown in (a), the back side Sb of the second wafer S is held by the adsorption holding plate 200, and the back side Wb of the first wafer W is held by the adsorption pad 210. Figure 5 As shown in (b), the adsorption pad 210 is raised while the adsorption pad 210 adsorbs and holds the first wafer W, so as to peel the first wafer W from the laser absorption layer P. At this time, since the bonding strength at the interface between the first wafer W and the laser absorption layer P is reduced by irradiation with the laser beam L as described above, the first wafer W can be separated from the laser absorption layer P without applying a large load.

[0079] The separated first wafer W is transferred to the transfer arm 23 of the wafer transfer device 22 by the suction pad 210, and is transferred to the second cleaning device 34. At this time, the first wafer W removed from the separation device 32 may be transferred to the second cleaning device 34 after being reversed by, for example, a reversing device (not shown) and the action of the suction pad 210 to turn the front and back surfaces so that the surface Wa faces upward.

[0080] In the second cleaning device 34, the surface Wa of the first wafer W, which is the surface separated by the separation device 32, is cleaned. In addition, in the second cleaning device 34, the back surface Wb may be cleaned together with the surface Wa. In addition, a cleaning unit for cleaning the surface Wa and a cleaning unit for cleaning the back surface Wb may be provided separately. Thereafter, the first wafer W cleaned by the second cleaning device 34 is transported by the wafer transport device 22 to the cassette Cw of the cassette mounting table 11.

[0081] On the other hand, the second wafer S held on the adsorption holding disk 200 is handed over to the transfer arm 23 and transferred to the first cleaning device 33. In the first cleaning device 33, the surface Sa side of the second wafer S, which is the side separated by the separation device 32, specifically, the surface of the laser absorption layer P is cleaned. In addition, in the first cleaning device 33, the back side Sb of the second wafer S can also be cleaned together with the surface of the laser absorption layer P. In addition, a cleaning section for cleaning the surface of the laser absorption layer P and a cleaning section for cleaning the back side Sb of the second wafer S can also be provided separately. Thereafter, the second wafer S cleaned by the first cleaning device 33 is transferred by the wafer transfer device 22 to the box Cs of the box mounting table 11.

[0082] In this way, a series of wafer processing in the wafer processing system 1 is completed.

[0083] Next, the details of the mechanism related to the reduction in the bonding strength between the first wafer W and the laser absorption layer P caused by the irradiation of the laser beam L at the processing position A2 of the laser irradiation device 31 described above will be described.

[0084] As described above, at the processing position A2 of the laser irradiation device 31, the laser beam L is irradiated from the back surface Wb side of the first wafer W to the overlapped wafers T held on the holding plate 100 ( Figure 7 Step St11). Figure 6 As shown, the laser beam L outputted from the lens 113 of the laser irradiation unit 110 passes through the silicon (first wafer W) and is absorbed by the laser absorption layer P ( Figure 7 Step St12).

[0085] The laser beam L absorbed by the laser absorption layer P is converted into heat according to its energy distribution ( Figure 7 In other words, the temperature of the laser absorption layer P rises due to the absorption of the laser beam L. The temperature of the laser absorption layer P is highest in the area directly below the irradiation of the laser beam L.

[0086] The heat (Ht in the figure) generated in the laser absorption layer P due to the absorption of the laser beam L is as follows: Figure 8 As shown, most of it diffuses toward the first wafer W side ( Figure 7 In other words, due to the heat diffusion from the laser absorption layer P, the temperature of the interface between the laser absorption layer P and the first wafer W (silicon) rises.

[0087] When the heat generated in the laser absorption layer P diffuses toward the first wafer W, due to the influence of the heat, that is, the increase in the interface temperature between the laser absorption layer P and the first wafer W, as shown in FIG. Fig. 9As shown, the region of the first wafer W at the irradiation portion of the laser beam L locally expands (plastically deforms in a downward convex shape toward the laser absorption layer P side) according to its temperature distribution ( Figure 7 Step St15).

[0088] Hereinafter, a region affected by heat generated by irradiation with the laser beam L may be referred to as an “irradiation region R” of the laser beam L. In other words, the first wafer W locally expands in the irradiation region R of the laser beam L.

[0089] Here, when the first wafer W expands, the laser absorption layer P is pressed from the upper side (the first wafer W side) along with the expansion of the first wafer W. Fig. 9 As shown, compressive stress σ1 is generated in the region of the laser absorption layer P at the irradiation position of the laser beam L. Fig. 9 As shown, the generated compressive stress σ1 acts in a direction of peeling the first wafer W and the laser absorption layer P (downward direction and the laser absorption layer P side in the figure) to generate a peeling stress σ2.

[0090] In other words, in the irradiation region R of the laser beam L, the silicon (first wafer W) expands and generates compressive stress σ1 in the region directly below the irradiation of the laser beam L (the central portion of the irradiation region R), and at the end portion Re of the irradiation region R (refer to Fig. 9 ) generates a peeling stress σ2 in the peeling direction caused by the compressive stress σ1. The peeling stress σ2 is a tensile stress generated at the end Re of the irradiated region R.

[0091] The generated compressive stress σ1 and peeling stress σ2 are accumulated inside the laser absorption layer P. At this time, at the end Re of the irradiation region R, the peeling stress σ2 generated in the plurality of irradiation regions R acts in a cooperative (repeated) manner.

[0092] Moreover, when the cumulative total amount (cooperative amount) of the peeling stress σ2 at the end Re of the irradiated region R exceeds the adhesion force Σ per unit area of ​​the first wafer W and the laser absorption layer P at the end Re (n×σ2>Σ (where n is the number of irradiations of the laser beam L, which is a natural number)), as Fig.10 As shown, peeling occurs at the interface between the first wafer W and the laser absorption layer P at the end Re of the irradiation region R, and as a result, the bonding strength between the laser absorption layer P and the first wafer W is reduced ( Figure 7 Step St16).

[0093] Furthermore, the stress σ (compression stress σ1 and peeling stress σ2 ) accumulated inside the laser absorption layer P is released due to the peeling of the first wafer W and the laser absorption layer P.

[0094] Furthermore, at the processing position A2 of the laser irradiation device 31, as shown in FIG. Fig.11 As shown in FIG. 1 , when viewed from above, peeling occurs on the entire surface of the interface between the first wafer W and the laser absorption layer P. In other words, the entire surface of the interface between the first wafer W and the laser absorption layer P is connected to the peeling generated at the end Re of the irradiation region R, thereby reducing the bonding strength on the entire surface of the first wafer W and the laser absorption layer P. As a result, the first wafer W and the laser absorption layer P can be properly separated in the separation device 32 ( Figure 7 Step St17).

[0095] Furthermore, ideally, in the overlapped wafer T after irradiation with the laser beam L at the processing position A2, the first wafer W is peeled off from the laser absorption layer P over the entire surface. In other words, after peeling occurs at the end Re of the irradiation region R, the first wafer W is also peeled off from the laser absorption layer P at the center of the irradiation region R including the region directly below the irradiation due to the peeling stress σ2. However, as Fig.10 As shown, in the central part of the irradiation region R (the region directly below the irradiation of the laser beam L), sometimes the first wafer W is maintained in a state of being connected to the laser absorption layer P (not detached) after peeling occurs at the end Re of the irradiation region R. Therefore, in the wafer processing system 1 involved in the technology disclosed in the present invention, in order to reliably separate the first wafer W from the overlapped wafer T (laser absorption layer P) in the overlapped wafer T after irradiation of the laser beam L, it is preferable to configure a separation device 32, and set a step of separating the first wafer W from the overlapped wafer T in the separation device 32.

[0096] Here, in the case where the first wafer W is separated from the overlapping wafer T in the separation device 32 as described above, if the overlapping wafer T is transported to the separation device 32 in the above-mentioned ideal state, that is, in a state in which separation from the laser absorption layer P occurs on the entire surface of the first wafer W, there is a possibility that the first wafer W falls from the second wafer S due to the inertial force accompanying the transportation.

[0097] In addition, if peeling occurs on the entire surface of the first wafer W from the laser absorption layer P as described above, it is possible that although there is no need to transport the overlapping wafer T after irradiation with the laser beam L to the separation device 32, when the laser beam L at the processing position A2 irradiates the laser absorption layer P, the first wafer W may fly out from the second wafer S due to the centrifugal force caused by the rotation of the retaining disk 100.

[0098] In view of this point, it is preferred to control the irradiation conditions (irradiation position, output, etc.) of the laser beam L at the processing position A2 so that at least a portion of the interface between the first wafer W and the laser absorption layer P remains connected (unpeeled off) to prevent the first wafer W from flying away or falling during the irradiation of the laser beam L to the laser absorption layer P and during the transportation of the overlapping wafer T.

[0099] This prevents the first wafer W from being completely separated from the laser absorption layer P and from flying away from the second wafer S and falling during the irradiation of the laser beam L or during the transport to the separation device 32 .

[0100] The reduction of the bonding strength between the first wafer W and the laser absorption layer P at the processing position A2 of the laser irradiation device 31 is performed as described above. That is, in the present embodiment, in the laser irradiation device 31, the first wafer W is expanded by the heat generated by the irradiation of the laser beam L, and a compressive stress σ1 is generated in the laser absorption layer P, thereby generating a peeling stress σ2 in the peeling direction at the interface between the first wafer W and the laser absorption layer P, thereby generating peeling at the interface between the first wafer W and the laser absorption layer P, thereby reducing the bonding strength.

[0101] In addition, in the above embodiment, if Fig. 9 As shown, the laser absorption layer P is irradiated with the laser beam L multiple times. When the cumulative total amount of the peeling stress σ2 generated thereby exceeds the adhesion ∑ between the first wafer W and the laser absorption layer P, peeling occurs at the end Re of the irradiated area R. However, the number of irradiations with the laser beam L until the peeling occurs is not necessarily multiple times.

[0102] For example, when the peeling stress σ2 generated by a single (one-time) irradiation of the laser beam L exceeds the adhesion Σ at the end Re, peeling sometimes occurs at the interface between the first wafer W and the laser absorption layer P at the end Re of the irradiated area R due to the irradiation of the single laser beam L.

[0103] Next, details of a method of irradiating the laser beam L to the laser absorption layer P at the processing position A2 of the laser irradiation device 31 described above will be described.

[0104] First, if Fig.13 As shown, the regions of the overlapped wafer T (laser absorption layer P) when viewed from above are set as the outer peripheral region Z0, the first inner peripheral region Z1, the second inner peripheral region Z2, and the central region Z3 ( Fig.12 Step St20). Specifically, for example, the operator sets the outer peripheral area Z0, the first inner peripheral area Z1, the second inner peripheral area Z2 and the central area Z3, and these outer peripheral area Z0, the first inner peripheral area Z1, the second inner peripheral area Z2 and the central area Z3 are stored in the control device 40. The outer peripheral area Z0, the first inner peripheral area Z1, the second inner peripheral area Z2 and the central area Z3 are sequentially arranged from the radial outer side to the inner side. In addition, the outer peripheral area Z0, the first inner peripheral area Z1 and the second inner peripheral area Z2 are arranged concentrically with the overlapped wafer T, and the central area Z3 is arranged concentrically with the overlapped wafer T.

[0105] like Fig.13 and Fig.14As shown, the peripheral area Z0 is an area including an unbonded area Q where the first wafer W (surface film Fw) and the second wafer S (surface film Fs) are not bonded to the peripheral area of ​​the overlapping wafer T, and a bonded area B radially inward of the unbonded area Q. The unbonded area Q includes a chamfered portion (bevel portion) formed by chamfering the peripheral portion. In addition, the unbonded area Q also includes an area where the first wafer W and the second wafer S are not bonded, for example, due to a positional offset of bonding or other reasons.

[0106] The first inner peripheral region Z1 , the second inner peripheral region Z2 , and the center region Z3 are regions disposed in the bonding region B between the first wafer W and the second wafer S, respectively.

[0107] Here, in the present embodiment, the overlapped wafer T is rotated, and the laser beam L is irradiated in a pulsed manner while the laser beam L is moved in the radial direction. At this time, it is preferable to make the interval of irradiating the laser beam L, that is, the interval of the pulses constant so as to uniformly perform the peeling of the first wafer W and the laser absorption layer P within the wafer surface. In this regard, in order to make the irradiation interval of the laser beam L constant, for example, the rotation speed of the overlapped wafer T is increased as the laser beam L moves from the radial outside to the inside. In addition, when the rotation speed of the overlapped wafer T reaches the upper limit, then, for example, the frequency of irradiating the laser beam L in a pulsed manner is decreased as the laser beam L moves from the radial outside to the inside. Moreover, when the rotation speed of the overlapped wafer T reaches the upper limit and the frequency of the laser beam reaches the lower limit, for example, the irradiation interval of the laser beam becomes smaller as the laser beam L moves from the radial outside to the inside, and the laser beam L sometimes overlaps in the center area of ​​the overlapped wafer T.

[0108] Therefore, in this embodiment, the outer peripheral area Z0, the first inner peripheral area Z1, and the second inner peripheral area Z2 are irradiated with the laser beam L while rotating the overlapped wafer T. Meanwhile, in the center area Z3, the laser beam L is scanned while the rotation of the overlapped wafer T is stopped.

[0109] In the outer peripheral area Z0 and the first inner peripheral area Z1, the frequency of the laser beam L is kept constant and the rotation speed of the overlapped wafer T is changed along with the radial movement of the laser beam L, so as to irradiate the laser beam L in a pulsed state. Specifically, when the laser beam L moves from the radial outside to the inside, the rotation speed of the overlapped wafer T is increased, and when the laser beam L moves from the radial inside to the outside, the rotation speed of the overlapped wafer T is decreased.

[0110] In the second inner peripheral area Z2, the rotation speed of the overlapped wafer T is kept constant and the frequency of the laser beam L is changed along with the radial movement of the laser beam L, so as to irradiate the laser beam L in a pulsed state. Specifically, when the laser beam L moves from the radial outside to the inside, the frequency of the laser beam L is reduced, and when the laser beam L moves from the radial inside to the outside, the frequency of the laser beam L is increased.

[0111] The boundary position between the first inner region Z1 and the second inner region Z2 is set at a position where the rotation speed of the overlapped wafer T reaches an upper limit. The boundary position between the second inner region Z2 and the center region Z3 is set at a position where the frequency of the laser beam L reaches a lower limit.

[0112] Next, the laser absorption layer P is irradiated with a laser beam L. At this time, the processing conditions of the laser processing are changed for each of the regions Z0 to Z3. In addition, in the present embodiment, the laser beam L is sequentially irradiated to the peripheral region Z0 ( Fig.12 Step St21), irradiation of the second inner peripheral area Z2 with the laser beam L ( Fig.12 Step St22), irradiation of the first inner peripheral area Z1 with the laser beam L ( Fig.12 Step St23), and irradiation of the central area Z3 with the laser beam L ( Fig.12 Step St24).

[0113] In step St21, in the peripheral area Z0, as Fig.15 As shown, the holding disk 100 (the overlapped wafer T held on the holding disk 100) is rotated counterclockwise by the rotating mechanism 103, and the holding disk 100 is moved in the positive direction of the Y axis by the moving mechanism 104 while irradiating the laser beam L in a pulsed manner. At this time, the laser beam L is not scanned but fixed. In this way, the laser beam L is irradiated in a spiral shape from the radial inside to the outside in the outer peripheral area Z0. In addition, according to the above-mentioned peeling mechanism of the first wafer W and the laser absorption layer P generated by the irradiation of the laser beam L, as shown in FIG. Fig.16 As shown, peeling occurs at the interface between the first wafer W and the laser absorption layer P in the outer peripheral region Z0.

[0114] In addition, since the peripheral region Z0 includes the unbonded region Q, the bonding strength between the first wafer W and the second wafer S, that is, the bonding strength between the surface film Fw and the surface film Fs, is low at the boundary between the unbonded region Q and the bonded region B. In this case, when the laser beam L is irradiated to the peripheral region Z0, as shown in FIG. Fig.17As shown, in the peripheral region Z0, when the peeling stress σ2 does not exceed the adhesion Σ between the first wafer W and the laser absorption layer P, no peeling occurs between the first wafer W and the laser absorption layer P. Moreover, the convex shape of the interface between the first wafer W and the laser absorption layer P is transmitted to the surface film Fw, and stress is applied to the interface between the surface film Fw and the surface film Fs. Due to this stress, peeling sometimes occurs at the interface between the surface film Fw and the surface film Fs with low bonding strength at the boundary between the unbonded region Q and the bonded region B. In this state, if the laser beam L is moved from the radial outside to the inside and irradiated in the peripheral region Z0, the peeling easily progresses with the interface between the surface film Fw and the surface film Fs where the peeling occurs as the front end in the bonded region B adjacent to the radial inside of the unbonded region Q. That is, sometimes in the bonded region B of the peripheral region Z0, peeling does not occur at the desired interface between the first wafer W and the laser absorption layer P.

[0115] Therefore, in this embodiment, the laser beam L is irradiated from the radial inside to the outside in the outer peripheral area Z0. Fig.16 As shown, in the bonding area B, peeling E1 occurs at the interface between the first wafer W and the laser absorption layer P. At this time, stress σ is generated in each irradiation area R in such a way that peeling E1 occurs from the central part to the end Re. In order to generate a large stress σ in this way, for example, the frequency of the laser beam L can be increased (the spacing of the laser beam L can also be shortened), or the irradiation intensity of the laser beam L can be increased. In addition, since the bonding strength of the interface between the surface film Fw and the surface film Fs is low at the boundary between the bonding area B and the unbonded area Q, peeling E2 is generated, extending from the interface between the first wafer W and the laser absorption layer P toward the interface between the surface film Fw and the surface film Fs. In addition, even if peeling E2 occurs, since the area of ​​the device layer Dw that is radially outside the peeling E2 is a device that is not commercialized, it has no effect.

[0116] Next, in step St22, in the second inner circumference area Z2, as Fig.18 As shown in FIG. 1 , the holding disk 100 is rotated counterclockwise by the rotating mechanism 103, and the holding disk 100 is moved in the positive direction of the Y axis by the moving mechanism 104 while irradiating the laser beam L in a pulsed manner. At this time, the laser beam L is not scanned but fixed. In this way, the laser beam L is irradiated in a spiral shape from the radial inside to the outside in the second inner circumference area Z2. In addition, in the second inner circumference area Z2, as shown in FIG. Fig.11 As shown, delamination occurs at the interface between the first wafer W and the laser absorption layer P.

[0117] Next, in step St23, in the first inner circumference area Z1, as Fig.18As shown, the laser beam L is also continuously irradiated to the second inner peripheral area Z2 in step St22. That is, the holding disk 100 is rotated counterclockwise by the rotating mechanism 103, and the laser beam L is irradiated in a pulsed state while the holding disk 100 is moved in the positive direction of the Y axis by the moving mechanism 104. At this time, the laser beam L is fixed without scanning.

[0118] Thus, in step St23, the laser beam L is irradiated in the first inner circumference area Z1 in a spiral shape from the radial inside to the outside. The spiral shape of the laser beam L in the first inner circumference area Z1 is continuous with the spiral shape of the laser beam L in the second inner circumference area Z2 and the spiral shape of the laser beam L in the outer circumference area Z0. That is, in the outer circumference area Z0, the first inner circumference area Z1, and the second inner circumference area Z2, the rotation direction of the disk 100 is kept counterclockwise, and the irradiation direction (movement direction) of the laser beam L is from the radial inside to the outside, so the spiral shape of the laser beam L is continuous.

[0119] In addition, in step St23, if Fig.19 As shown, in the first inner peripheral region Z1, peeling occurs at the interface between the first wafer W and the laser absorption layer P. The peeling at the interface between the first wafer W and the laser absorption layer P in the first inner peripheral region Z1 is continuous with the peeling at the interface between the first wafer W and the laser absorption layer P in the second inner peripheral region Z2 and the peeling at the interface in the outer peripheral region Z0.

[0120] In addition, in the second inner circumference area Z2 of step St22 and the first inner circumference area Z1 of step St23, in each irradiation area R, the first wafer W and the laser absorption layer P are peeled off or the bonding force is weak at the end Re, and the first wafer W and the laser absorption layer P are connected at the center. That is, compared with the outer circumference area Z0, the stress σ accumulated inside the laser absorption layer P is small in the second inner circumference area Z2 and the first inner circumference area Z1. In order to generate a small stress σ like this, for example, the frequency of the laser beam L can be reduced (the pitch of the laser beam L can also be lengthened), or the irradiation intensity of the laser beam L can be reduced. When the pitch of the laser beam L is lengthened, the time spent on laser processing can be shortened and the throughput can be improved. In addition, when the irradiation intensity of the laser beam L is reduced, laser processing can be performed efficiently.

[0121] Here, if a large stress σ that completely peels off the interface between the first wafer W and the laser absorption layer P is generated in the second inner circumferential region Z2 and the first inner circumferential region Z1 and the stress σ is accumulated, the first wafer W may be broken. Therefore, as described above, in the second inner circumferential region Z2 and the first inner circumferential region Z1, the first wafer W and the laser absorption layer P are peeled off in a state where at least a part of the interface between the first wafer W and the laser absorption layer P is still connected, so as to suppress the cracking of the first wafer W.

[0122] Moreover, when Fig.19 As shown, when the peeling E3 of the interface between the first wafer W and the laser absorption layer P in the first inner peripheral area Z1 is connected to the peeling E1 in the outer peripheral area Z0, the entire surface of the interface between the first wafer W and the laser absorption layer P in the first inner peripheral area Z1 and the second inner peripheral area Z2 is peeled. In addition, the above-mentioned "state where the bonding force between the first wafer W and the laser absorption layer P at the end Re is weak" means that when the peeling E3 of the interface between the first wafer W and the laser absorption layer P in the first inner peripheral area Z1 is connected to the peeling E1 in the outer peripheral area Z0 like this, the bonding force at the end Re will produce a degree of peeling.

[0123] Next, in step St24, the rotation of the holding disk 100 is stopped in the center area Z3. Then, the laser beam L is irradiated in a pulsed manner from the laser irradiation unit 110. In addition, the laser beam L is scanned in the center area Z3. Fig. 20 As shown, the scanning irradiation of the laser beam L in the X-axis direction and the movement of the holding disk 100 (overlapping wafer T) in the Y-axis direction are repeated and alternated. Alternatively, the scanning irradiation of the laser beam L in the X-axis direction and the movement of the holding disk 100 in the negative direction of the Y-axis can also be performed synchronously. In addition, the laser beam L can also be branched by the above-mentioned optical system 112 to simultaneously irradiate the laser beam L to multiple points of the laser absorption layer P to improve the throughput of wafer processing. In addition, according to the above-mentioned peeling mechanism of the first wafer W and the laser absorption layer P generated by the irradiation of the laser beam L, peeling occurs at the interface between the first wafer W and the laser absorption layer P in the central area Z3.

[0124] According to the present embodiment, by performing steps St20 to St24 , delamination can occur at the interface between the first wafer W and the laser absorption layer P. As a result, the first wafer W and the laser absorption layer P can be separated, and the device layer Dw of the first wafer W can be transferred to the second wafer S.

[0125] In addition, in step St21, the laser beam L is moved from the radial inside to the outside and irradiated in the outer peripheral area Z0, so that peeling can be caused at the interface between the first wafer W and the laser absorption layer P. In this way, the bonding strength of the interface between the first wafer W and the laser absorption layer P can be reduced, and the first wafer W and the laser absorption layer P can be peeled.

[0126] In addition, the laser beam L is continuously irradiated from the radial inside to the outside in the second inner circumference area Z2 of step St22 and the first inner circumference area Z1 of step St23, so that the peeling at the interface between the first wafer W and the laser absorption layer P can be appropriately connected.

[0127] Furthermore, in view of the fact that the overlapped wafer T after irradiation with the laser beam L in the laser irradiation device 31 is appropriately transported as described above, it is preferred that at least a portion of the interface between the first wafer W and the laser absorption layer P is still connected. Therefore, it is preferred that at least a portion of the interface between the first wafer W and the laser absorption layer P is maintained in a state of being still connected in at least any one of the first inner peripheral region Z1, the second inner peripheral region Z2, and the central region Z3.

[0128] Furthermore, in order to achieve the effect of the above embodiment, that is, to generate peeling at least in the outer peripheral region Z0 at the interface between the first wafer W and the laser absorption layer P, the outer peripheral region Z0 may be irradiated with the laser beam L from the radial inside to the outside. Other processing conditions are not limited to the above embodiment.

[0129] Specifically, the processing conditions of the laser processing can be arbitrarily changed for each of the zones Z0 to Z3. The processing conditions include, for example, the rotation speed of the holding disk 100, the frequency of the laser beam L, the rotation direction of the holding disk 100, the processing order of the zones Z0 to Z3 (the irradiation order of the laser beam L), and the like.

[0130] For example, you can also Fig.21 As shown, the second inner peripheral area Z2 is irradiated with the laser beam L, the first inner peripheral area Z1 is irradiated with the laser beam L, the outer peripheral area Z0 is irradiated with the laser beam L, and the center area Z3 is irradiated with the laser beam L in sequence.

[0131] In this case, if Fig.21 As shown in (a), in the second inner circumference area Z2 and the first inner circumference area Z1, similar to steps St22 and St23, the retaining disk 100 is rotated counterclockwise by the rotating mechanism 103, and the laser beam L is irradiated in a pulsed manner while the retaining disk 100 is moved in the positive direction of the Y axis by the moving mechanism 104.

[0132] In the second inner circumference area Z2 and the first inner circumference area Z1, in each irradiation area R, the first wafer W and the laser absorption layer P are peeled off or the bonding force is weak at the end Re, and the first wafer W is connected to the laser absorption layer P at the center. That is, in the second inner circumference area Z2 and the first inner circumference area Z1, the stress σ accumulated inside the laser absorption layer P is reduced. As described above, if a large stress σ is generated and accumulated, the first wafer W may break. In this regard, by reducing the stress σ as in the present embodiment, the breakage of the first wafer W can be suppressed. In addition, the above-mentioned "state of weak bonding force between the first wafer W and the laser absorption layer P at the end Re" refers to a bonding force of the degree of peeling that will be generated at the end Re when the peeling E3 of the interface between the first wafer W and the laser absorption layer P in the first inner circumference area Z1 is connected to the peeling E1 in the outer circumference area Z0.

[0133] Then, if Fig.21 As shown in (b), in the peripheral region Z0, similarly to step St21, the holding disk 100 is rotated counterclockwise by the rotating mechanism 103, and the holding disk 100 is moved in the positive direction of the Y axis by the moving mechanism 104 while being irradiated with the laser beam L in a pulsed manner. In the peripheral region Z0, a large stress σ is generated in each irradiation region R so that peeling E1 occurs from the central portion to the end portion Re.

[0134] Next, in the center region Z3, similarly to step St24, the laser beam L is scanned while the rotation of the holding plate 100 is stopped. Then, in the center region Z3, separation occurs at the interface between the first wafer W and the laser absorption layer P.

[0135] In this embodiment, the same effects as those of the above-described embodiment can be achieved. That is, separation can occur at the interface between the first wafer W and the laser absorption layer P.

[0136] In addition, for example, Fig. 22 As shown, the laser beam L is irradiated in the first inner circumference area Z1 and the second inner circumference area Z2 while moving from the radial outside to the inside. In this case, the laser beam L irradiates the outer circumference area Z0, the laser beam L irradiates the first inner circumference area Z1, the laser beam L irradiates the second inner circumference area Z2, and the laser beam L irradiates the center area Z3 in sequence.

[0137] First, if Fig. 22 As shown in (a), in the peripheral region Z0, similarly to step St21, the holding disk 100 is rotated counterclockwise by the rotating mechanism 103, and the holding disk 100 is moved in the positive direction of the Y axis by the moving mechanism 104 while being irradiated with the laser beam L in a pulsed manner. In this way, the laser beam L is irradiated in a spiral shape from the radial inside to the outside in the peripheral region Z0. In the peripheral region Z0, a large stress σ is generated in each irradiation region R in such a manner that peeling E1 occurs from the central portion to the end portion Re.

[0138] Then, if Fig. 22 As shown in (b), in the first inner peripheral area Z1, the holding disk 100 is rotated clockwise by the rotating mechanism 103, and the holding disk 100 is moved in the negative direction of the Y axis by the moving mechanism 104 while irradiating the laser beam L in a pulsed manner. In this way, the laser beam L is irradiated in the first inner peripheral area Z1 in a spiral shape from the radial outside to the inside.

[0139] In this case, in the adjacent outer circumference area Z0 and the first inner circumference area Z1, the rotation direction of the holding disk 100 is opposite, and the irradiation direction of the laser beam L is also opposite. In this way, the spiral shape of the laser beam L can be made continuous in the outer circumference area Z0 and the first inner circumference area Z1. In other words, when the irradiation direction of the laser beam L is different in adjacent areas, if the rotation direction of the holding disk 100 in the adjacent areas is made opposite, the spiral shape of the laser beam L can be made continuous.

[0140] Next, in the second inner peripheral area Z2, the holding disk 100 is rotated clockwise by the rotating mechanism 103, and the holding disk 100 is moved in the negative direction of the Y axis by the moving mechanism 104 while being irradiated with the laser beam L in a pulsed manner. In this way, the laser beam L is irradiated in the second inner peripheral area Z2 in a spiral manner from the radial outside to the inside.

[0141] In addition, in the first inner peripheral region Z1 and the second inner peripheral region Z2, the magnitude of the stress σ accumulated inside the laser absorption layer P is not limited. When the first inner peripheral region Z1 is irradiated with the laser beam L, the peeling of the interface between the first wafer W and the laser absorption layer P caused by the laser beam L is connected to the peeling E1 in the outer peripheral region Z0. Therefore, in the first inner peripheral region Z1, peeling is appropriately generated at the interface between the first wafer W and the laser absorption layer P. Moreover, the peeling is also transmitted to the second inner peripheral region Z2, and peeling is also appropriately generated at the interface between the first wafer W and the laser absorption layer P in the second inner peripheral region Z2.

[0142] Next, in the center region Z3, similarly to step St24, the laser beam L is scanned while the rotation of the holding plate 100 is stopped. Then, in the center region Z3, separation occurs at the interface between the first wafer W and the laser absorption layer P.

[0143] In this embodiment, the same effects as those of the above-described embodiment can be achieved. That is, separation can be caused at the interface between the first wafer W and the laser absorption layer P.

[0144] In the above embodiment, in step St20, the inner peripheral area is set to two areas, namely, the first inner peripheral area Z1 and the second inner peripheral area Z2, but the inner peripheral area may be one. In the inner peripheral area, the frequency of the laser beam L may be made constant and the rotation speed of the overlapped wafer T may be changed along with the radial movement of the laser beam L, so as to irradiate the laser beam L in a pulsed manner. Alternatively, in the inner peripheral area, the rotation speed of the overlapped wafer T may be made constant and the frequency of the laser beam L may be changed along with the radial movement of the laser beam L, so as to irradiate the laser beam L in a pulsed manner. In short, in the inner peripheral area, the processing conditions are controlled so that the irradiation interval of the laser beam L becomes constant.

[0145] In the above embodiment, the holding disk 100 is moved in the horizontal direction during laser processing, but the lens 113 of the laser irradiation unit 110 may be moved in the horizontal direction, or both the holding disk 100 and the lens 113 may be moved in the horizontal direction. By relatively moving the holding disk 100 and the lens 113 in the horizontal direction, laser processing using the laser beam L can be performed.

[0146] In the above embodiment, in step St24, the laser beam L is irradiated to the center area Z3 in a scanning manner while the rotation of the holding disk 100 is stopped. Fig.23 As shown, the laser irradiation unit 110 scans and irradiates the laser beam L while rotating the holding disk 100. In this case, the rotation speed of the holding disk 100 in the central area Z3 may be lower than that in the outer area Z0, the first inner area Z1, and the second inner area Z2.

[0147] In the above embodiment, the laser beam L is irradiated in a spiral shape in the outer circumference area Z0, the first inner circumference area Z1, and the second inner circumference area Z2, but the laser beam L may be irradiated in a concentric annular shape. Fig.23 In the illustrated embodiment, the laser beam L is also irradiated in the central area Z3 in a spiral shape, but the laser beam L may be irradiated in a concentric ring shape.

[0148] In the above implementation, if Figure 8 to Figure 11 As shown, peeling occurs at the interface between the first wafer W and the laser absorption layer P. However, as described above, a peeling-promoting film for appropriately peeling the first wafer W and the laser absorption layer P may be formed on the surface Wa of the first wafer W. In this case, peeling may also occur at the interface between the peeling-promoting film and the laser absorption layer P.

[0149] Specifically, if Fig.24 As shown in (a), a peeling promotion film Pe, a laser absorption layer P, a device layer Dw, and a surface film Fw as a stacked film can be sequentially stacked on the surface Wa of the first wafer W. The peeling promotion film Pe is formed to facilitate the peeling of the first wafer W from the second wafer S, and is formed of a material that has lower adhesion to the first wafer W (silicon) than to the laser absorption layer P and is transparent to the laser beam L, such as silicon nitride (SiN).

[0150] When separating the first wafer W from the second wafer S, first, the laser absorption layer P is irradiated with the laser beam L ( Fig.25 The laser beam L passes through the first wafer W and the peeling promotion film Pe and is absorbed by the laser absorption layer P ( Fig.25 Step St32).

[0151] The laser beam L absorbed by the laser absorption layer P is converted into heat according to its energy distribution ( Fig.25 Step St33), whereby the temperature of the laser absorption layer P rises. Most of the heat generated in the laser absorption layer P due to absorption of the laser beam L diffuses toward the peeling promotion film Pe on the first wafer W side ( Fig.25 In step St34), due to the thermal diffusion, the temperature of the interface between the laser absorption layer P and the peeling-promoting film Pe rises.

[0152] When the heat generated in the laser absorption layer P diffuses toward the first wafer W, due to the influence of the heat, that is, the increase in the interface temperature between the laser absorption layer P and the peeling promotion film Pe, as shown in FIG. Fig.24 As shown in (b), the peeling promotion film Pe locally expands according to its temperature distribution ( Fig.25 Step St35). At this time, the thermal influence of the interface between the laser absorption layer P and the peeling promotion film Pe may affect the first wafer W, so that Fig.24 As shown in (b), the first wafer W also partially expands according to the temperature distribution.

[0153] Thereafter, when the peeling promoting film Pe (and the first wafer W) partially expands, due to the stress generated by the expansion, as shown in FIG. Fig.24 As shown in (c), peeling occurs at the interface between the laser absorption layer P having low adhesion and the peeling-promoting film Pe, and as a result, the bonding strength between the laser absorption layer P and the peeling-promoting film Pe is reduced ( Fig.25 Step St36). Moreover, the entire surface of the interface between the peeling-promoting film Pe and the laser absorption layer P is peeled off, thereby reducing the bonding strength over the entire surface of the peeling-promoting film Pe and the laser absorption layer P, thereby enabling the peeling-promoting film Pe and the laser absorption layer P (the first wafer W and the second wafer S) to be properly separated in the separation device 32 ( Fig.25 Step St37).

[0154] By forming a peeling-promoting film Pe on the surface Wa of the first wafer W whose adhesion to the first wafer W (silicon) is lower than its adhesion to the laser absorption layer P, and expanding the peeling-promoting film Pe as a substitute for or in addition to expanding the first wafer W, the transfer of the device layer Dw formed on the surface Wa of the first wafer W can also be appropriately performed.

[0155] In addition, Fig.24In the example shown, a peeling-promoting film Pe is formed at the interface between the first wafer W and the laser absorption layer P, but for example, it can also be set that the peeling-promoting film Pe is formed at the interface between the laser absorption layer P and the device layer Dw, and peeling occurs at the interface between the laser absorption layer P and the peeling-promoting film Pe, so that the peeling-promoting film Pe remains on the side of the second wafer S which is the transfer destination of the device layer Dw.

[0156] It should be considered that all points of the embodiments disclosed this time are illustrative and not restrictive. The above embodiments may be omitted, replaced, or changed in various ways without departing from the attached claims and their gist. For example, the constituent elements of the above embodiments may be combined arbitrarily. From this arbitrary combination, the functions and effects of each constituent element involved in the combination can be obtained, and other functions and effects that are clear to those skilled in the art based on the description of this specification can be obtained.

[0157] In addition, the effects described in this specification are only illustrative or exemplary, and are not limiting. That is, the technology involved in the present disclosure can play other effects that can be clearly understood by those skilled in the art based on the description of this specification as a supplement or replacement for the above-mentioned effects.

[0158] Description of Reference Numerals

[0159] 31: laser irradiation device; 40: control device; 100: holding disk; 103: rotation mechanism; 104: movement mechanism; 110: laser irradiation unit; L: laser beam; P: laser absorption layer; S: second wafer; T: overlapped wafer; W: first wafer.

Claims

1. A substrate processing device for processing a superimposed substrate formed by laminating a first substrate, an interface layer including at least a laser absorption layer, and a second substrate, the substrate processing device comprising: a substrate holding portion, which holds the overlapped substrates; a laser irradiation section that irradiates a laser beam toward the superimposed substrates held by the substrate holding section; a moving mechanism that moves the substrate holding portion and the laser irradiation portion relative to each other in a horizontal direction; a rotating mechanism that rotates the substrate holding portion; and Control Department, in, The superimposed substrate includes an outer peripheral region including a non-bonded region between the first substrate and the second substrate, and an inner peripheral region which is arranged radially inward of the outer peripheral region and is a bonded region between the first substrate and the second substrate. The control unit performs the following control: The superimposed substrate is rotated, and the laser beam is irradiated while the superimposed substrate is moved in a radial direction, so as to cause peeling at an interface between the first substrate and the laser absorption layer, or at an interface between the interface layer and the laser absorption layer; and At least in the outer peripheral region, the laser beam is irradiated while being moved from the inner side to the outer side in the radial direction.

2. The substrate processing apparatus according to claim 1, wherein: The inner peripheral region is provided with a first inner peripheral region on the outer side in the radial direction and a second inner peripheral region on the inner side in the radial direction. The control unit performs the following control: In the first inner peripheral area, the frequency of the laser beam is kept constant and the rotation speed of the superimposed substrate is changed along with the movement of the laser beam, so as to irradiate the laser beam in a pulsed state; as well as In the second inner peripheral area, the rotation speed of the superimposed substrate is kept constant and the frequency of the laser beam is changed along with the movement of the laser beam, so that the laser beam is irradiated in a pulsed state.

3. The substrate processing apparatus according to claim 1 or 2, wherein: The control unit performs control to irradiate the inner peripheral region with the laser beam while moving the laser beam from the inner side to the outer side in the radial direction.

4. The substrate processing apparatus according to claim 3, wherein: The control unit performs control to irradiate the laser beam so that the stress generated by the laser beam in the outer peripheral region is greater than the stress generated by the laser beam in the inner peripheral region.

5. The substrate processing apparatus according to claim 1 or 2, wherein: The control unit performs control to irradiate the inner peripheral region with the laser beam while moving the laser beam from the outer side to the inner side in the radial direction.

6. The substrate processing apparatus according to claim 1 or 2, wherein: The control unit performs control such that, when the moving directions of the laser beams in adjacent regions are different, the rotation directions of the superimposed substrates in the adjacent regions are opposite to each other.

7. The substrate processing apparatus according to claim 1 or 2, wherein: The control unit performs control to irradiate the inner peripheral region with the laser beam after irradiating the outer peripheral region with the laser beam.

8. The substrate processing apparatus according to claim 1 or 2, wherein: The control unit performs control to irradiate the outer peripheral region with the laser beam after irradiating the inner peripheral region with the laser beam.

9. The substrate processing apparatus according to claim 1 or 2, wherein: The superimposed substrate is set to be arranged radially inward of the inner peripheral region and in a central region of a bonding region between the first substrate and the second substrate. The control unit performs control to irradiate the center region with the laser beam while scanning in a state where the rotation of the superimposed substrate is stopped.

10. The substrate processing apparatus according to claim 1 or 2, wherein: The interface layer includes a peeling-promoting film, The delamination of the interface between the interface layer and the laser absorption layer is caused at the interface between the delamination promoting film and the laser absorption layer.

11. A substrate processing method, processing a superimposed substrate formed by laminating a first substrate, an interface layer including at least a laser absorption layer, and a second substrate, the substrate processing method comprising: An outer peripheral region including an unbonded region between the first substrate and the second substrate and an inner peripheral region disposed radially inward of the outer peripheral region and a bonded region between the first substrate and the second substrate are set in the superimposed substrate; The overlapping substrates are held by a substrate holding portion; The superimposed substrate held by the substrate holding portion is rotated, and a laser beam is irradiated from a laser irradiation portion while the superimposed substrate is moved in a radial direction, so as to cause peeling at an interface between the first substrate and the laser absorption layer, or at an interface between the interface layer and the laser absorption layer; and At least in the outer peripheral region, the laser beam is irradiated while being moved from the inner side to the outer side in the radial direction.

12. The substrate processing method according to claim 11, further comprising: A first inner peripheral region close to the radial outer side and a second inner peripheral region close to the radial inner side are set in the inner peripheral region; In the first inner peripheral area, the frequency of the laser beam is kept constant and the rotation speed of the superimposed substrate is changed along with the movement of the laser beam, so as to irradiate the laser beam in a pulsed state; as well as In the second inner peripheral area, the rotation speed of the superimposed substrate is kept constant and the frequency of the laser beam is changed along with the movement of the laser beam, so that the laser beam is irradiated in a pulsed state.

13. The substrate processing method according to claim 11 or 12, wherein: The inner peripheral region is irradiated with the laser beam while being moved from the inner side to the outer side in the radial direction.

14. The substrate processing method according to claim 13, wherein: The laser beam is irradiated in such a manner that the stress generated by the laser beam in the outer peripheral region is greater than the stress generated by the laser beam in the inner peripheral region.

15. The substrate processing method according to claim 11 or 12, wherein: The inner peripheral area is irradiated with the laser beam while being moved from the outer side to the inner side in the radial direction.

16. The substrate processing method according to claim 11 or 12, wherein: When the moving directions of the laser beams in adjacent regions are different, the rotation directions of the superimposed substrates in the adjacent regions are made opposite.

17. The substrate processing method according to claim 11 or 12, wherein: After the outer peripheral region is irradiated with the laser beam, the inner peripheral region is irradiated with the laser beam.

18. The substrate processing method according to claim 11 or 12, wherein: After the inner peripheral region is irradiated with the laser beam, the outer peripheral region is irradiated with the laser beam.

19. The substrate processing method according to claim 11 or 12, further comprising: The superimposed substrate is set to be arranged radially inward of the inner peripheral area and at a central area of ​​a bonding area between the first substrate and the second substrate; as well as In the center area, the laser beam is irradiated while scanning in a state where the rotation of the superimposed substrate is stopped.

20. The substrate processing method according to claim 11 or 12, wherein: The interface layer includes a peeling-promoting film, The delamination of the interface between the interface layer and the laser absorption layer is caused at the interface between the delamination promoting film and the laser absorption layer.

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