Substrate processing method and substrate processing device

Abstract

A substrate processing method for processing a polymerized substrate in which a first substrate and a second substrate are bonded, wherein a laser absorption layer is formed on the second substrate, and a peeling modification layer is formed by irradiating the laser absorption layer with laser light in a pulse shape, and stress is accumulated inside the laser absorption layer, and the accumulated stress is sequentially released, and the second substrate is peeled.

Description

Technology Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] Patent document 1 discloses a method for manufacturing a semiconductor device. This method for manufacturing a semiconductor device includes a heating process in which a CO2 laser is irradiated from the back side of a semiconductor substrate to locally heat a peeling oxide film, and a transfer process in which peeling occurs at least one of the peeling oxide film and the interface between the peeling oxide film and the semiconductor substrate, thereby transferring the semiconductor device to a transfer substrate. Prior art literature

[0003] Japanese Patent Publication No. 2007-220749 The problem to be solved

[0004] The technology according to the present disclosure comprises, in a polymerized substrate in which a first substrate and a second substrate are bonded, appropriately peeling off the second substrate from the first substrate. means of solving the problem

[0005] One aspect of the present disclosure is a substrate processing method for processing a polymerized substrate in which a first substrate and a second substrate are bonded, wherein a laser absorption layer is formed on the second substrate, a laser light is irradiated in a pulsed shape onto the laser absorption layer to form a peeling modification layer, stress is accumulated inside the laser absorption layer, and the accumulated stress is sequentially released to peel off the second substrate. Effects of the invention

[0006] According to the present disclosure, in a polymerized substrate in which a first substrate and a second substrate are bonded, the second substrate can be appropriately peeled off from the first substrate. Brief explanation of the drawing

[0007] FIG. 1 is a side view showing an example of a polymerized wafer processed in a wafer processing system. Figure 2 is a plan view schematically showing the configuration of a wafer processing system. Figure 3 is a side view showing a schematic configuration of a laser irradiation device for an interface. Figure 4 is a plan view showing a schematic configuration of a laser irradiation device for an interface. FIG. 5 is an explanatory diagram showing the formation of a peeling modified layer according to the present embodiment. FIG. 6 is a plan view showing an example of forming a peeling modified layer according to the present embodiment. FIG. 7 is an explanatory diagram showing the flow of wafer processing according to the present embodiment. FIG. 8 is a plan view showing another example of forming a peeling modified layer according to the present embodiment. FIG. 9 is an explanatory diagram showing the peeling of the second wafer according to the present embodiment. FIG. 10 is a plan view showing another example of forming a peeling modified layer according to the present embodiment. FIG. 11 is an explanatory diagram schematically showing the configuration of a laser irradiation unit according to another embodiment. FIG. 12 is an explanatory diagram showing the frequency of laser light being changed by an acousto-optic modulator in another embodiment. FIG. 13 is an explanatory diagram showing the frequency of a laser light being changed by an acousto-optic modulator in another embodiment. FIG. 14 is an explanatory diagram schematically showing the configuration of a laser irradiation unit according to another embodiment. FIG. 15 is an explanatory diagram schematically showing the configuration of a laser irradiation unit according to another embodiment. FIG. 16 is an explanatory diagram showing the appearance of the peeled modified layer formed in the present embodiment. FIG. 17 is a plan view showing another example of forming a peeling modified layer according to the present embodiment. FIG. 18 is an explanatory diagram showing another example of peeling of a second wafer according to the present embodiment. Figure 19 is an explanatory diagram showing the appearance of the pressing of the second wafer. FIG. 20 is an explanatory diagram showing the appearance of pressing the second wafer. FIG. 21 is a side view showing a schematic configuration of a polymerization wafer in another embodiment. FIG. 22 is an explanatory diagram showing the flow of edge trim processing according to the present embodiment. Specific details for implementing the invention

[0008] Recently, in the LED manufacturing process, so-called laser lift-off is being performed, which involves peeling off a GaN (gallium nitride)-based compound crystal layer (material layer) from a sapphire substrate using laser light. The reason for this laser lift-off is that since the sapphire substrate is transparent to short-wavelength laser light (e.g., UV light), it is possible to use short-wavelength laser light with a high absorption rate in the absorption layer, thereby offering a wide range of choices for the laser light.

[0009] Meanwhile, in the manufacturing process of semiconductor devices, a device layer formed on the surface of one substrate (such as a silicon substrate for semiconductors) is transferred to another substrate. Although silicon substrates are generally transparent to laser light in the NIR (near-infrared) region, there is a risk that the device layer may be damaged because the absorption layer is also transparent to NIR laser light. Therefore, to perform laser lift-off in the semiconductor device manufacturing process, laser light in the FIR (far-infrared) region is used.

[0010] Generally, laser light of the FIR wavelength can be used, for example, by a CO2 laser. In the method described in the aforementioned patent document 1, a CO2 laser is irradiated onto a peeling oxide film as an absorption layer, thereby causing peeling at the interface between the peeling oxide film and the substrate.

[0011] Here, the inventors have carefully examined the case and found that simply irradiating the absorption layer with laser light (CO2 laser) alone does not cause delamination between the substrate and the peeling oxide film (device layer), meaning that proper transfer cannot be performed. In other words, they discovered that the cause of delamination is not the energy of the laser light, but the peak power (maximum intensity of the irradiated laser light). The peak power can be increased, for example, by lowering the frequency of the laser light.

[0012] As described above, in order to cause delamination of a substrate and an absorption layer (device layer) by irradiating with laser light as in the method described in Patent Document 1, it is necessary to increase the peak power, for example, by lowering the frequency of the laser light irradiated on the absorption layer. However, for example, if the frequency of the laser light is lowered in this way, the time required to delaminate the entire surface of the substrate and the absorption layer increases, and the throughput related to the transfer of the device layer decreases. Furthermore, in the method of Patent Document 1, the frequency of the laser light is not fully considered, nor is there any indication thereof. Therefore, there is room for improvement in the conventional method of transferring the device layer.

[0013] The technology according to the present disclosure comprises, in a polymerized substrate in which a first substrate and a second substrate are bonded, appropriately peeling off the second substrate from the first substrate. Hereinafter, a wafer processing system as a substrate processing apparatus and a wafer processing method as a substrate processing method according to the present embodiment will be described with reference to the drawings. Furthermore, in the present specification and drawings, elements having substantially the same functional configuration are given the same reference numerals to omit redundant descriptions.

[0014] As shown in FIG. 1, the polymerization wafer (T) as a polymerization substrate processed in the wafer processing according to the present embodiment is formed by bonding a first wafer (W1) as a first substrate and a second wafer (W2) as a second substrate. Hereinafter, in the first wafer (W1), the side surface that is bonded to the second wafer (W2) is referred to as the surface (W1a), and the side opposite to the surface (W1a) is referred to as the back surface (W1b). Likewise, in the second wafer (W2), the side surface that is bonded to the first wafer (W1) is referred to as the surface (W2a), and the side opposite to the surface (W2a) is referred to as the back surface (W2b).

[0015] The first wafer (W1) is a semiconductor wafer, for example, a silicon substrate. A device layer (D1) containing a plurality of devices is formed on the surface (W1a) of the first wafer (W1). A surface film (F1) is also formed on the device layer (D1), and is bonded to the second wafer (W2) via the surface film (F1). Examples of the surface film (F1) include an oxide film (SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive. Additionally, there may be cases where the device layer (D1) and the surface film (F1) are not formed on the surface (W1a).

[0016] The second wafer (W2) is also a semiconductor wafer, for example, a silicon substrate. On the surface (W2a) of the second wafer (W2), a laser absorption layer (P), a device layer (D2), and a surface film (F2) are formed by stacking them in this order from the surface (W2a) side, and are bonded to the first wafer (W1) through the surface film (F2). The device layer (D2) and the surface film (F2) are each identical to the device layer (D1) and the surface film (F1) of the first wafer (W1). As for the laser absorption layer (P), as described later, it may be an oxide film (SiO2 film, TEOS film), etc., capable of absorbing laser light (e.g., CO2 laser). Additionally, there may be cases where the laser absorption layer (P), the device layer (D2), and the surface film (F2) are not formed on the surface (W2a). In this case, the laser absorption layer (P) is formed on the surface (W1a) of the first wafer (W1) on which the device layer (D1) and the surface film (F1) are formed, and the device layer (D1) is transferred to the second wafer (W2).

[0017] The periphery (We) of the second wafer (W2) is chamfered, so the thickness of the cross-section of the periphery (We) decreases toward its leading edge. In the manufacturing process of a semiconductor device, the back surface of the second wafer (W2) formed in this way is removed to thin it, and in this thinning process, there is a risk that the periphery (We) will become sharply pointed (so-called knife edge shape). Then, chipping may occur at the periphery (We) of the second wafer (W2), and there is a risk that the second wafer (W2) will be damaged. Therefore, the edge trimming described later, which removes the periphery (We) of the second wafer (W2) in advance before this thinning process, may be performed. The periphery (We) is the part removed in this edge trimming, and is, for example, a range of 0.5 mm to 3 mm in diameter from the outer edge of the second wafer (W2).

[0018] In the wafer processing system (1) described below according to the present embodiment, the aforementioned laser lift-off processing as wafer processing, i.e., transfer processing on the first wafer (W1) side of the device layer (D2), or the aforementioned edge trim processing as wafer processing, i.e., removal processing of the peripheral portion (We) of the second wafer (W2) is performed.

[0019] As shown in FIG. 2, the wafer processing system (1) has a configuration in which an incoming / outgoing block (G1), a return block (G2), and a processing block (G3) are connected as a single unit. The incoming / outgoing block (G1), the return block (G2), and the processing block (G3) are arranged in this order from the X-axis negative direction side.

[0020] In the incoming / outgoing block (G1), cassettes (Ct, Cw1, Cw2) capable of accommodating a plurality of polymerized wafers (T), a plurality of first wafers (W1), and a plurality of second wafers (W2), respectively, are each brought in and out of the block, for example, from the outside. A cassette placement table (10) is provided in the incoming / outgoing block (G1). In the illustrated example, a plurality, for example, three cassettes (Ct, Cw1, Cw2) can be arranged in a line in the Y-axis direction on the cassette placement table (10). Additionally, the number of cassettes (Ct, Cw1, Cw2) placed on the cassette placement table (10) is not limited to this embodiment and can be determined arbitrarily.

[0021] In the transfer block (G2), a wafer transfer device (20) is provided adjacent to the cassette placement table (10) on the X-axis forward side of the cassette placement table (10). The wafer transfer device (20) is configured to be movable along a transfer path (21) that extends in the Y-axis direction. Additionally, the wafer transfer device (20) has, for example, two transfer arms (22, 22) that hold and transfer a polymerized wafer (T), a first wafer (W1), and a second wafer (W2). Each transfer arm (22) is configured to be movable in the horizontal direction, the vertical direction, around the horizontal axis, and around the vertical axis. Furthermore, the configuration of the transfer arm (22) is not limited to this embodiment and can take any configuration. And, the wafer transport device (20) is configured to transport the polymerized wafer (T), the first wafer (W1), and the second wafer (W2) to the cassette (Ct, Cw1, Cw2) of the cassette placement table (10) and the transition device (30) described later.

[0022] In the transfer block (G2), a transition device (30) for transferring a polymerized wafer (T), a first wafer (W1), and a second wafer (W2) is provided adjacent to the wafer transfer device (20) on the X-axis forward side of the wafer transfer device (20).

[0023] The processing block (G3) has a wafer transport device (40), a peripheral removal device (50), a cleaning device (60), an internal laser irradiation device (70), and an interface laser irradiation device (80).

[0024] The wafer transport device (40) is configured to be movable along a transport path (41) that extends in the X-axis direction. Additionally, the wafer transport device (40) has, for example, two transport arms (42, 42) that hold and transport the polymerized wafer (T), the first wafer (W1), and the second wafer (W2). Each transport arm (42) is configured to be movable in the horizontal direction, the vertical direction, around the horizontal axis, and around the vertical axis. Additionally, the configuration of the transport arm (42) is not limited to the present embodiment and can take any configuration. Furthermore, the wafer transport device (40) is configured to transport the polymerized wafer (T), the first wafer (W1), and the second wafer (W2) to the transition device (30), the edge removal device (50), the cleaning device (60), the internal laser irradiation device (70), and the interface laser irradiation device (80).

[0025] The edge removal device (50) is provided on the Y-axis forward side of the wafer transport device (40) and performs the removal of the edge portion (We) of the second wafer (W2), i.e., edge trimming treatment. The cleaning device (60) is provided on the Y-axis negative side of the wafer transport device (40) and performs cleaning of the polymerized wafer (T) after peeling or after the removal of the edge portion (We). The internal laser irradiation device (70), which serves as the second laser irradiation unit, is provided on the Y-axis forward side of the wafer transport device (40) and irradiates laser light (internal laser light, for example, a YAG laser) into the interior of the second wafer (W2) to form the edge modification layer (M2) described later, which serves as the starting point for peeling the edge portion (We). The interface laser irradiation device (80) is provided on the Y-axis side of the wafer transport device (40) and irradiates laser light (interface laser light, e.g., CO2 laser) onto the laser absorption layer (P) formed on the surface (W2a) of the second wafer (W2). Additionally, the configuration of the interface laser irradiation device (80) will be described later.

[0026] The above wafer processing system (1) is provided with a control device (90) as a control unit. The control device (90) 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 a polymerized wafer (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, such as the various processing devices and transport devices described above, to realize the wafer processing described later in the wafer processing system (1). Furthermore, the above program may be recorded on a computer-readable storage medium (H) and installed on the control device (90) from said storage medium (H).

[0027] The wafer processing system (1) is configured as described above, and in the wafer processing system (1), the laser lift-off processing of the polymerized wafer (T) described above, that is, the transfer processing of the device layer (D2) on the first wafer (W1), and the edge trimming processing of the second wafer (W2) described above can be performed respectively. In addition, for example, if the edge trimming processing of the second wafer (W2) is not performed in the wafer processing system (1), the edge removal device (50) and the internal laser irradiation device (70) can be omitted.

[0028] Next, the above-described laser irradiation device (80) for the interface will be explained.

[0029] As shown in FIGS. 3 and 4, the laser irradiation device (80) for the interface has a chuck (100) that holds a polymerized wafer (T) in its upper surface. The chuck (100) holds a portion of the back surface (W1b) or the front surface of the first wafer (W1) by adsorption. The chuck (100) is provided with a lifting pin (not shown) for transferring the polymerized wafer (T) between the chuck and a transport arm (42). The lifting pin is configured to be able to move up and down by inserting and passing through a through hole (not shown) formed through the chuck (100), and supports the polymerized wafer (T) from below and moves it up and down.

[0030] The chuck (100) is supported on the slider table (102) via an air bearing (101). A rotation mechanism (103) is provided on the lower side of the slider table (102). The rotation mechanism (103) incorporates, for example, a motor as a driving source. The chuck (100) is configured to rotate around the θ-axis (vertical axis) via the air bearing (101) by means of the rotation mechanism (103). The slider table (102) is configured to move along a rail (105) that extends in the Y-axis direction and is provided on a support (106) by means of a moving mechanism (104) provided on its lower side. Additionally, the driving source of the moving mechanism (104) is not particularly limited, but for example, a linear motor is used.

[0031] A laser irradiation unit (110) is provided above the chuck (100). The laser irradiation unit (110) has a laser head (111), an optical system (112), and a lens (113). The laser head (111) emits laser light in a pulse shape. The optical system (112) controls the intensity or position of the laser light, or attenuates the laser light to adjust the output. The lens (113) is a tube-shaped member and irradiates laser light onto a polymer wafer (T) held in the chuck (100). In this embodiment, the laser light is pulsed CO2 laser light, and the laser light emitted from the laser irradiation unit (110) passes through the second wafer (W2) and is irradiated onto the laser absorption layer (P). In addition, the wavelength of the CO2 laser light is, for example, 8.9 μm to 11 μm. Additionally, the lens (113) is configured to be movable by a lifting mechanism (not shown).

[0032] Additionally, a return pad (120) is provided above the chuck (100), having an adsorption surface on its lower surface for adsorbing and holding the back surface (W2b) of the second wafer (W2). The return pad (120) is configured to be movable by a lifting mechanism (not shown). The return pad (120) returns the second wafer (W2) between the chuck (100) and the return arm (42). Specifically, the chuck (100) is moved to the lower side of the return pad (120) (transfer position with the return arm (42)), the return pad (120) is lowered to adsorb and hold the back surface (W2b) of the second wafer (W2), and then the return pad (120) is raised again to detach it from the first wafer (W1). The peeled second wafer (W2) is transferred from the return pad (120) to the return arm (42) and is removed from the interface laser irradiation device (80). Additionally, the return pad (120) may be configured to invert the front and back surfaces of the wafer by means of an inversion mechanism (not shown).

[0033] Next, wafer processing performed using the wafer processing system (1) configured as described above will be explained. In addition, the following description describes the case where laser lift-off processing is performed in the wafer processing system (1), that is, the case where the device layer (D2) of the second wafer (W2) is transferred to the first wafer (W1). In addition, in this embodiment, the first wafer (W1) and the second wafer (W2) are bonded in an external bonding device (not shown) of the wafer processing system (1) so that a polymerized wafer (T) is formed in advance.

[0034] First, a cassette (Ct) containing multiple polymerized wafers (T) is placed on the cassette placement stand (10) of the incoming / outgoing block (G1). Next, the polymerized wafers (T) inside the cassette (Ct) are removed by the wafer transport device (20). The polymerized wafers (T) removed from the cassette (Ct) are transferred to the wafer transport device (40) via the transition device (30) and then transported to the interface laser irradiation device (80). In the interface laser irradiation device (80), the second wafer (W2) is peeled off (laser trim-off processing) from the first wafer (W1).

[0035] Specifically, the polymer wafer (T) adsorbed and held in the chuck (100) via a lifting pin from the return arm (42) is first moved to a processing position by the moving mechanism (104). This processing position is a position where laser light can be irradiated onto the polymer wafer (T) (laser absorption layer (P)) from the laser irradiation unit (110).

[0036] Next, as shown in FIGS. 5 and 6, a laser light (L) (CO2 laser light) is irradiated in a pulse shape from the laser irradiation unit (110) toward the back surface (W2b) of the second wafer (W2). At this time, the laser light (L) passes through the second wafer (W2) from the back surface (W2b) of the second wafer (W2) and is absorbed in the laser absorption layer (P). Then, stress is generated inside the laser absorption layer (P) that has absorbed the laser light (L). Hereinafter, the stress accumulation layer formed by the irradiation of the laser light in this manner, which serves as the starting point for peeling of the second wafer (W2) (the starting point for transfer of the device layer (D2)), may be referred to as the ‘peeling modification layer (M1)’. In addition, almost all of the energy of the laser light (L) irradiated onto the laser absorption layer (P) is absorbed by the formation of the peeling modification layer (M1), so it does not reach the device layer (D2). Because of this, damage to the device layer (D2) can be suppressed.

[0037] Here, the laser light (L) irradiated onto the laser absorption layer (P) is controlled to an output that does not cause the second wafer (W2) and the laser absorption layer (P) to peel off due to the irradiation of the laser light (L). In other words, for example, by increasing the frequency of the laser light (L) to lower the peak power, a peeling modification layer (M1) is formed so that peeling of the second wafer (W2) and the laser absorption layer (P) does not occur due to the irradiation of the laser light (L).

[0038] In this way, by preventing delamination of the second wafer (W2) and the laser absorption layer (P) by irradiation with laser light (L) and eliminating the escape route for the generated stress, the generated stress accumulates within the laser absorption layer (P), thereby forming a delamination modification layer (M1). More specifically, for example, the laser absorption layer (P) is gasified by irradiation with laser light, and by eliminating the escape route for the generated gas as described above, compressive stress accumulates as the delamination modification layer (M1). In addition, for example, heat is generated in the laser absorption layer (P) by absorption of laser light, and shear stress accumulates as the delamination modification layer (M1) due to the difference in the coefficient of thermal expansion between the laser absorption layer (P) and the second wafer (W2) or the device layer (D2). In addition, by accumulating stress generated by irradiation of laser light without causing delamination between the second wafer (W2) and the laser absorption layer (P) in this manner, the bonding strength between the laser absorption layer (P) and the second wafer (W2) is reduced at the formation location of the delamination modification layer (M1).

[0039] Additionally, when a laser beam (L) is irradiated onto the laser absorption layer (P), the chuck (100) (polymer wafer (T)) is rotated by the rotation mechanism (103), and the chuck (100) is moved in the Y-axis direction by the movement mechanism (104). Then, the laser beam (L) is irradiated onto the laser absorption layer (P) from the inner side in the diameter direction toward the outer side, and as a result, is irradiated in a spiral shape from the inner side toward the outer side. Also, the black arrow shown in FIG. 6 indicates the rotation direction of the chuck (100).

[0040] Here, the formation interval of adjacent peeling modified layers (M1), in other words, the pulse interval (frequency) of the laser light (L), is controlled to a interval such that peeling does not occur in the adjacent peeling modified layers (M1) due to the impact generated during the formation of the peeling modified layers (M1). Specifically, for example, as shown in FIG. 7 (a), it is preferable that the adjacent peeling modified layers (M1) are formed so that they do not overlap each other when viewed from a planar perspective. In addition, at this time, it is preferable that the adjacent peeling modified layers (M1) are formed in close proximity to each other.

[0041] In addition, as shown in FIG. 8, the laser light (L) may be irradiated in a circular shape in the laser absorption layer (P). However, in this case, since the rotation of the chuck (100) and the movement of the chuck (100) in the Y direction are performed alternately, irradiating the laser light (L) in a spiral shape as described above can improve throughput by shortening the irradiation time.

[0042] In addition, in this embodiment, when irradiating the laser light (L) onto the laser absorption layer (P), the chuck (100) is rotated, but the lens (113) may be moved so that the lens (113) is rotated relative to the chuck (100). In addition, the chuck (100) is moved in the Y-axis direction, but the lens (113) may be moved in the Y-axis direction. Furthermore, the formation direction of the peeling modification layer (M1) is not limited to the inner side in the diameter direction of the laser absorption layer (P) and may be formed from the outer side in the diameter direction toward the inner side.

[0043] When a plurality of peeling modification layers (M1) are formed continuously in this manner, as shown in FIG. 7 (a), a region in which the peeling modification layer (M1) is formed without peeling of the second wafer (W2) and the laser absorption layer (P) (hereinafter referred to as the 'unpeeled region (R1)') is formed sequentially from the inner side in the diameter direction of the laser absorption layer (P) toward the outer side. In the unpeeled region (R1), stress generated during the formation of each peeling modification layer (M1) is accumulated as described above.

[0044] As the formation of the unpeeled region (R1) continues, as shown in FIG. 7 (b), the formation location of the peeled modified layer (M1) reaches the vicinity of the end of the second wafer (W2), in other words, the boundary (Ad) between the bonded region (Ac) where the first wafer (W1) and the second wafer (W2) are bonded, and the unbonded region (Ae) outside the diameter direction of the bonded region (Ac). Furthermore, the boundary (Ad) here may be, for example, the bonded end formed by the bonding of the first wafer (W1) and the second wafer (W2), or it may be intentionally formed by, for example, the removal of the bonding interface between the first wafer (W1) and the second wafer (W2). That is, the unbonded region (Ae) is a region outside the diameter direction of the boundary (Ad), and may be a region where the bonding strength between the first wafer (W1) and the second wafer (W2) is intentionally eliminated, for example, by removing the bonding interface, or may simply be a region outside the diameter direction of the bonding region (Ac) where the first wafer (W1) and the second wafer (W2) are actually bonded.

[0045] When the formation location of the peeling modified layer (M1) reaches the boundary (Ad), the stress accumulated in the peeling modified layer (M1) is released to the formation space of the unbonded region (Ae), that is, outside the polymerized wafer (T). When the accumulated stress is released, as shown in FIG. 7 (b), at the formation location of the peeling modified layer (M1) formed near the boundary (Ad), a force is applied in the thickness direction of the laser absorption layer (P), that is, in the peeling direction between the laser absorption layer (P) and the second wafer (W2), and peeling between the laser absorption layer (P) and the second wafer (W2) occurs.

[0046] Subsequently, when the laser absorption layer (P) and the second wafer (W2) are peeled off near the boundary (Ad), the peeling of the laser absorption layer (P) and the second wafer (W2) proceeds inward in the diameter direction of the laser absorption layer (P) due to the influence of the force acting in the thickness direction of the laser absorption layer (P) caused by this peeling. Then, the peeling that proceeds inward in the diameter direction reaches the adjacent peeling modification layer (M1). That is, peeling of the laser absorption layer (P) and the second wafer (W2) occurs at the formation location of the adjacent peeling modification layer (M1).

[0047] When delamination occurs at the formation location of the adjacent delamination modified layer (M1), the stress accumulated in the delamination modified layer (M1) is released. As a result, a force is applied in the thickness direction of the laser absorption layer (P) at the formation location of the delamination modified layer (M1), and the delamination between the laser absorption layer (P) and the second wafer (W2) proceeds further in the diameter direction.

[0048] And, as the peeling of the laser absorption layer (P) and the second wafer (W2), the release of stress, and the progression of peeling inward in the radial direction are repeated in a sequential manner as shown in Fig. 7 (c), a peeled region (R2) is sequentially formed from the outer side in the radial direction of the laser absorption layer (P) toward the inner side. Then, as the front surface of the second wafer (W2) is peeled from the laser absorption layer (P) (first wafer (W1)), the device layer (D2) of the second wafer (W2) is transferred toward the first wafer (W1).

[0049] According to the present embodiment, in the formation of a non-peeling region (R1), that is, in the continuous formation of a peeling modification layer (M1), the peak power (frequency) of the laser light (L) is controlled so as not to cause peeling between the laser absorption layer (P) and the second wafer (W2). Then, a peeling modification layer (M1) (hereinafter referred to as 'starting point modification layer (M1s)') that serves as a starting point for peeling is formed near the boundary (Ad) between the laser absorption layer (P) and the second wafer (W2), so that peeling naturally proceeds starting from the peeling modification layer (M1) of the non-peeling region (R1). As a result, since there is no need to lower the frequency of the laser light (L) in the peeling between the laser absorption layer (P) and the second wafer (W2), the time required for the transfer processing of the device layer (D2) is shortened, that is, the reduction in throughput is suppressed. In addition, since there is no need to increase the peak power of the laser light (L) in this way, the energy efficiency required for the transfer process of the device layer (D2) can be improved.

[0050] When the front surface of the second wafer (W2) is peeled off from the laser absorption layer (P), the chuck (100) is moved to a transfer position by the moving mechanism (104). At the transfer position, the back surface (W2b) of the second wafer (W2) is held in place by adsorption using the return pad (120) as shown in FIG. 9 (a), and then the second wafer (W2) is peeled off from the laser absorption layer (P) (first wafer (W1)) by raising the return pad (120) as shown in FIG. 9 (b). At this time, as described above, since peeling occurs at the interface between the laser absorption layer (P) and the second wafer (W2), the second wafer (W2) can be peeled off from the laser absorption layer (P) without applying a large load.

[0051] The peeled second wafer (W2) is transferred from the transfer pad (120) to the transfer arm (42) of the wafer transfer device (40) and transferred to the cassette (Cw2) of the cassette placement table (10). Additionally, the second wafer (W2) removed from the interface laser irradiation device (80) may have its surface (W2a) cleaned in the cleaning device (60) before being transferred to the cassette (Cw2).

[0052] Meanwhile, the first wafer (W1) held in the chuck (100) is transferred to the transfer arm (42) of the wafer transfer device (40) via a lifting pin and transferred to the cleaning device (60). In the cleaning device (60), the surface of the laser absorption layer (P), which is the peeling surface, is scrubbed clean. Additionally, in the cleaning device (60), the back surface (W1b) of the first wafer (W1) may be cleaned along with the surface of the laser absorption layer (P).

[0053] Afterward, the first wafer (W1), having undergone all processing related to the transfer of the first wafer (W1) of the device layer (D2), is transferred to the cassette (Cw1) of the cassette placement table (10) by the wafer transport device (20) via the transition device (30). In this way, a series of wafer processing in the wafer processing system (1) is completed.

[0054] According to the above embodiment, the output of the laser light (L) irradiated in the interface laser irradiation device (80) is controlled to a peak power that does not cause delamination between the laser absorption layer (P) and the second wafer (W2). That is, since there is no need to lower the frequency of the laser light (L) for delamination between the laser absorption layer (P) and the second wafer (W2), the decrease in throughput related to the transfer of the device layer (D2) to the first wafer (W1) is suppressed. Furthermore, even if the peak power of the laser light (L) is lowered in this way, delamination between the laser absorption layer (P) and the second wafer (W2) can be appropriately caused by releasing the stress accumulated by the formation of the delamination modification layer (M1).

[0055] In addition, in the above embodiment, stress is released by forming a peeling modification layer (M1) near the boundary (Ad) as a starting point modification layer (M1s) to initiate sequential peeling of the laser absorption layer (P) and the second wafer (W2), but the method of initiating peeling is not limited to this.

[0056] Specifically, for example, by forming a starting point modification layer (M1s) that serves as a starting point for peeling on the outer side of the unpeeled region (R1) formed on the laser absorption layer (P), sequential peeling of the laser absorption layer (P) and the second wafer (W2) may be initiated. At this time, the starting point modification layer (M1s) is formed with a high peak power (low frequency) such that peeling of the laser absorption layer (P) and the second wafer (W2) occurs by irradiation of laser light (L). By causing peeling by irradiation of laser light (L) in this way, compressive stress is released, and subsequently, peeling of the laser absorption layer (P) and the second wafer (W2) proceeds sequentially. And, even if the frequency is lowered to increase the peak power due to the formation of the base modification layer (M1s) as described above, the unpeeled region (R1) can be formed by the same method as in the above embodiment, so the decrease in throughput related to the transfer of the device layer (D2) to the first wafer (W1) can be suppressed.

[0057] In addition, in this case, a starting point modification layer (M1s) can be formed prior to the formation of the non-delamination region (R1). That is, by pre-delaminating the laser absorption layer (P) and the second wafer (W2) through the formation of the starting point modification layer (M1s), the formation location of the peeling modification layer (M1) as the non-delamination region (R1) subsequently reaches the formation location of the starting point modification layer (M1s), thereby releasing the compressive stress in the starting point modification layer (M1s) and initiating the progression of sequential peeling.

[0058] Here, in order to make the separation of the laser absorption layer (P) and the second wafer (W2) uniform within the plane, it is desirable to keep the interval of irradiating the laser light (L), that is, the interval of the pulses, constant. However, as described above, when the chuck (100) (polymer wafer (T)) is rotated during the irradiation of the laser light (L), the relative rotational speed of the chuck (100) with respect to the laser irradiation part (110) (lens (113)) is greater in the inner direction of the diameter than in the outer direction of the diameter. That is, even if the rotational speed of the chuck (100) is constant, if the irradiation position of the laser light (L) is in the inner direction of the diameter, the interval of the laser light (L) becomes smaller, and there may be cases where the laser light (L) overlaps in the center of the laser absorption layer (P). And, if the laser light (L) overlaps in this way, the laser absorption layer (P) and the second wafer (W2) in the center cannot be properly separated, or there is a risk that passing light of the laser light (L) will be generated and affect the device layer (D2).

[0059] Accordingly, in the present embodiment, regarding the peeling of the second wafer (W2) and the laser absorption layer (P), as shown in FIG. 10, the formation of the peeling modification layer (M1) may be omitted in the region where the peeling region (R2) is naturally extended and formed by the release of stress in the center (Pc) of the laser absorption layer (P). Even if the peeling modification layer (M1) is not formed in the center of the laser absorption layer (P) in this way, the peeling is extended by the action of peeling (stress release) proceeding from the outer side in the radial direction, so that the laser absorption layer (P) and the second wafer (W2) can be peeled even in the center.

[0060] In addition, in this embodiment, the frequency of the laser light (L) is reduced in the inner diameter direction where the relative rotational speed of the laser irradiation part (110) (lens (113)) of the chuck (100) is increased, and the frequency of the laser light (L) is increased in the outer diameter direction, so that the relative irradiation interval of the laser light (L) to the laser absorption layer (P) can be controlled to be approximately constant. However, when changing the frequency in this way, if the frequency of the laser light (L) is changed in the laser oscillator of the laser head (111), the pulse waveform of the said laser light (L) also changes. Therefore, complex adjustments considering the output or pulse waveform of the laser light (L) are required, making it difficult to control the laser processing process.

[0061] Accordingly, in this embodiment, the frequency of the laser light (L) is controlled using an acousto-optic modulator. As described above, the laser irradiation unit (110) has a laser head (111), an optical system (112), and a lens (113).

[0062] As shown in FIG. 11, the laser head (111) has a laser oscillator (130) that emits laser light in a pulse shape. The frequency of the laser light emitted from the laser oscillator (130) is the highest frequency that can be controlled by the acousto-optic modulator (131) described later. In addition, the laser head (111) may have other devices other than the laser oscillator (130), such as an amplifier.

[0063] The optical system (112) has an acousto-optic modulator (AOM) (131) as an optical element that diverts laser light from a laser oscillator (130) in a different direction, and an attenuator (132) as an attenuator that attenuates laser light from the laser oscillator (130) to adjust the output of the laser light. The acousto-optic modulator (131) and the attenuator (132) are arranged in this order from the laser oscillator (130) side.

[0064] The acousto-optic modulator (131) is an optical modulator that electrically controls the intensity and position of laser light at high speed. As shown in FIG. 12, when laser light (L1) from a laser oscillator (130) is incident, the acousto-optic modulator (131) applies a voltage to change the refractive index of the laser light (L1), thereby deviating the laser light (L1) in a different direction. Specifically, the angle of change of the laser light (L1) can be controlled by adjusting the voltage. In this embodiment, for example, the laser light (L1) is deviated in two different directions so that laser light (L2) in one direction is irradiated onto the laser absorption layer (P), and laser light (L3) in the other direction is not irradiated onto the laser absorption layer (P). By controlling the deviation of these laser lights (L2, L3), the frequency of the laser light (L2) irradiated onto the laser absorption layer (P) can be adjusted.

[0065] In this case, the frequency of the laser light (L2) irradiated onto the laser absorption layer (P) can be adjusted by using an acousto-optic modulator (131) to filter out the pulses of the laser light (L1). For example, at a certain timing, if the deviation ratio of the laser light (L2) and the laser light (L3) relative to the laser light (L1) is set to 100:0, the laser light (L1) becomes the laser light (L2) as is and is irradiated onto the laser absorption layer (P). On the other hand, at a different timing, if the deviation ratio of the laser light (L2) and the laser light (L3) relative to the laser light (L1) is set to 0:100, the laser light (L2) becomes 0 (zero) and the laser light (L2) is not irradiated onto the laser absorption layer (P). In this case, the frequency of the laser light (L2) diverted by the acousto-optic modulator (131) shown in FIG. 13 (b) can be adjusted with respect to the frequency of the laser light (L1) from the laser oscillator (130) shown in FIG. 13 (a). Furthermore, as described above, since the frequency of the laser light (L1) is the highest frequency that the acousto-optic modulator (131) can control, the frequency of the laser light (L2) can be adjusted arbitrarily. Also, the horizontal axis of FIG. 13 represents time, and the vertical axis represents the intensity of the laser light (L2). That is, the density in the graph of FIG. 13 represents the frequency of the laser light (L2).

[0066] Furthermore, in this case, since the frequency of the laser light (L1) oscillating from the laser oscillator (130) is not changed, the pulse waveform of the laser light (L1) does not change, and thus the pulse waveform of the laser light (L2) can be made identical to the pulse waveform of the laser light (L1). Therefore, the frequency of the laser light (L2) can be easily adjusted, and the conventional complex adjustments as described above become unnecessary, making it easier to control the laser processing process.

[0067] In addition, in this embodiment, an acousto-optic modulator (131) is used as the optical element, but it is not limited thereto. For example, an electro-optic modulator (EOM) may be used as the optical element. In addition, an optical deflector such as an acousto-optic deflector (AOD) or an electro-optic deflector (EOD) may be used.

[0068] Next, a method for controlling the laser light (L2) when irradiating the laser absorption layer (P) from the laser irradiation unit (110) is described. As described above, when the irradiation position of the laser light (L2) is outside the diameter direction of the laser absorption layer (P), the frequency is increased, and when the irradiation position of the laser light (L2) is inside, the frequency is decreased.

[0069] The following is an explanation using specific examples. Furthermore, the numerical values ​​in this specific example are merely examples, and the present disclosure is not limited to these numerical values. For example, the energy required for peeling is set to 400 μJ for each of the outer and inner sides in the radial direction of the laser absorption layer (P). The required frequency of the laser light (L2) in the outer side in the radial direction of the laser absorption layer (P) is set to 100 kHz, and the required frequency of the laser light in the inner side is set to 50 kHz. The frequency of the laser light (L1) from the laser oscillator (130) is set to 100 kHz, and the output is set to 40 W.

[0070] In this case, the laser light (L1) pulse from the laser oscillator (130) is not filtered out in the radial outer direction of the laser absorption layer (P) in the acousto-optic modulator (131). Then, the frequency of the laser light (L2) irradiated onto the laser absorption layer (P) can be 100 kHz, which is the same as the frequency of the laser light (L1). Also, the output of the laser light (L2) becomes 40 W, which is the same as the output of the laser light (L1). And, the energy of the laser light (L2) becomes 400 μJ (= 40 W / 100 kHz), so peeling can be performed properly.

[0071] Meanwhile, regarding the inner side in the diameter direction of the laser absorption layer (P), the pulse of the laser light (L1) from the laser oscillator (130) is cut in half by the acousto-optic modulator (131). Then, the frequency of the laser light (L2) irradiated onto the laser absorption layer (P) can be set to 50 kHz, which is half the frequency of the laser light (L1). Also, by cutting out the laser light (L1), the output of the laser light (L2) also becomes 20 W, which is half the output of the laser light (L1). And, the energy of the laser light (L2) becomes 400 μJ (= 20 W / 50 kHz), so peeling can be performed properly.

[0072] In this way, the rotational speed of the chuck (100) is controlled so that the pulse interval becomes constant according to the frequency and irradiation position of the laser light (L2). Then, at the center of the laser absorption layer (P), the maximum rotational speed of the chuck (100) is maintained, and the acousto-optic modulator (131) adjusts the frequency of the laser light (L2) to match the maximum rotational speed. By doing so, laser processing can be performed while maintaining the maximum high rotational speed of the chuck (100) and the high frequency of the laser light (L2), thereby realizing high-throughput laser processing.

[0073] Furthermore, in this case, since the frequency of the laser light (L1) from the laser oscillator (130) is not changed, the pulse waveform of the laser light (L1) does not change, and the pulse waveform of the laser light (L2) can be made identical to the pulse waveform of the laser light (L1). Therefore, the frequency of the laser light (L2) can be easily adjusted, making continuous seamless processing possible. As a result, process control of the laser processing is easy, and a stable process can be realized.

[0074] In addition, in this embodiment, since the output of the laser light (L1) from the laser oscillator (130) was 40 W, it was unnecessary to adjust the output for the energy of 400 μJ required for peeling. For example, if the output of the laser light (L1) was 50 W, the output of the laser light (L1) could be adjusted by attenuating it by 20% in the attenuator (132).

[0075] In the laser irradiation unit (110) of the above embodiment, the acousto-optic modulator (131) is provided upstream of the attenuator (132) inside the optical system (112), but the installation location is not limited thereto. For example, as shown in FIG. 14, the acousto-optic modulator (131) may be provided downstream of the attenuator (132) inside the optical system (112). Or, for example, as shown in FIG. 15, the acousto-optic modulator (131) may be provided downstream of the laser oscillator (130) inside the laser head (111). In addition, the acousto-optic modulator (131) may be provided at two or more locations at the above installation location.

[0076] Additionally, in the laser irradiation unit (110), after adjusting the frequency and output of the laser light (L2) with an acousto-optic modulator (131), it is possible to fine-tune the output with an attenuator (132). Here, the output of the laser light (L1) oscillated from the laser oscillator (130) may become non-uniform due to individual differences in the laser oscillator (130). The attenuator (132) can adjust this non-uniformity of the output. Furthermore, when monitoring the output of the laser light (L1) from the laser oscillator (130) over time, the output can be adjusted by feedback control of the attenuator (132). And, from the perspective of fine-tuning the output of the laser light (L2) with the attenuator (132) in this way, it is preferable that the acousto-optic modulator (131) be provided upstream of the attenuator (132) as shown in FIG. 11.

[0077] In the laser irradiation unit (110) of the above embodiment, the attenuator (132) may be omitted. For example, the output of the laser light (L2) can be adjusted using an acousto-optic modulator (131) instead of the attenuator (132). For example, when the output of the laser light (L1) is 50 W and the output of the laser light (L2) required for peeling is 40 W, if the deviation ratio of the laser light (L2) and the laser light (L3) with respect to the laser light (L1) in the acousto-optic modulator (131) is set to 80:20, the output of the laser light (L2) can be set to 40 W.

[0078] In addition, in the above embodiment, a peeling modification layer (M1) is formed on the laser absorption layer (P) such that the bonding strength between the second wafer (W2) and the laser absorption layer (P) is reduced, and peeling between the second wafer (W2) and the laser absorption layer (P) is performed starting from the peeling modification layer (M1). However, as shown in FIG. 16 (a), for example, if a region (hereinafter referred to as the "unformed region (R3)") is formed within the plane of the laser absorption layer (P) where laser light is not irradiated and the bonding strength is not reduced, it may not be possible to properly perform peeling between the second wafer (W2) and the laser absorption layer (P). Specifically, as shown in FIG. 16 (b), for example, in the unformed region (R3) where the bonding strength is not reduced, there is a risk that a part of the second wafer (W2) (silicon piece) will remain on the surface of the laser absorption layer (P) after peeling.

[0079] Accordingly, in the present embodiment, it is preferable to form a peeling modified layer (M1) (unpeeled area (R1)) so as to reduce the formation area of ​​the unpeeled area (R3) within the plane of the laser absorption layer (P). Specifically, the unpeeled area (R3) can be reduced by controlling the formation position of the peeling modified layer (M1), for example as shown in FIG. 17 (a), and increasing the number of other peeling modified layers (M1) adjacent to one peeling modified layer (M1). In addition, the unpeeled area (R3) may be reduced by controlling the laser irradiation type for the laser absorption layer (P), for example as shown in FIG. 17 (b). That is, the laser irradiation type may be, for example, a square. And, by reducing the area of ​​the unformed region (R3) in this way, the region where the bonding strength with the second wafer (W2) within the plane of the laser absorption layer (P) is reduced increases, and as a result, the laser absorption layer (P) and the second wafer (W2) can be properly peeled off.

[0080] In addition, in the above embodiment, a laser absorption layer (P), a device layer (D2), and a surface film (F2) were stacked in this order on the surface (W2a) of the second wafer (W2), but a peeling promotion layer (P2) may be further formed between the second wafer (W2) and the laser absorption layer (P), as shown in FIG. 18 (a). As for the peeling promotion layer (P2), silicon nitride (SiN) is selected, for example, as a material that has transmittance to laser light (CO2 laser) and has adhesion to the second wafer (W2) (silicon) that is at least less than adhesion to the laser absorption layer (P) (SiO2).

[0081] As shown in FIG. 18(b), in the transfer of the device layer (D2) on the polymer wafer (T) on which the peeling promotion layer (P2) is formed, a laser light (L) (CO2 laser light) is first irradiated in a pulse shape toward the back side (W2b) of the second wafer (W2). At this time, the laser light (L) passes through the second wafer (W2) and the peeling promotion layer (P2) from the back side (W2b) of the second wafer (W2) and is absorbed by the laser absorption layer (P). Then, a peeling modification layer (M1) is formed inside the laser absorption layer (P) that has absorbed the laser light (L).

[0082] Here, the stress generated by the irradiation of the laser light (L) typically remains at the irradiation location of the laser light (L) (inside the laser absorption layer) as shown in the above embodiment, forming a peeling modification layer (M1). However, when a peeling promotion layer (P2) is formed as in the present embodiment, the adhesion between the peeling promotion layer (P2) and the second wafer (W2) is smaller than the adhesion between the peeling promotion layer (P2) and the laser absorption layer (P). Therefore, as shown in FIG. 18 (c), the generated stress penetrates the peeling promotion layer (P2) and accumulates at the interface between the peeling promotion layer (P2) and the second wafer (W2). In other words, the stress generated by irradiating the laser light (L) moves to and accumulates at the interface between the peeling promotion layer (P2) and the second wafer (W2), where it can remain more stably, and thereby the bonding strength between the peeling promotion layer (P2) and the second wafer (W2) is reduced.

[0083] And, since the bonding strength between the peeling promotion layer (P2) and the second wafer (W2) is reduced in this way, peeling between the peeling promotion layer (P2) and the second wafer (W2) can be performed appropriately thereafter. Also, at this time, because the adhesion between the peeling promotion layer (P2) and the second wafer (W2) is low, as shown in FIG. 16, the remaining of a portion of the second wafer (W2) on the surface of the peeling promotion layer (P2) after peeling is appropriately suppressed. Furthermore, in this embodiment, since the laser absorption layer (P) absorbs the laser light (L), damage remaining on the exposed surface after peeling, that is, the surface (W2a) of the second wafer (W2) or the surface of the peeling promotion layer (P2), is more appropriately suppressed.

[0084] In addition, when peeling is properly performed at the interface between the peeling promotion layer (P2) and the second wafer (W2) in this manner, the gas generated by the irradiation of laser light needs to pass through the peeling promotion layer (P2). However, if the film thickness of the peeling promotion layer (P2) is large, the generated gas does not properly pass through the peeling promotion layer (P2), and peeling may occur at the interface between the peeling promotion layer (P2) and the laser absorption layer (P). Therefore, in order to properly perform peeling at the interface between the peeling promotion layer (P2) and the second wafer (W2), the film thickness of the peeling promotion layer (P2) is thin relative to the laser absorption layer (P), and specifically, for example, it is desirable to have a film thickness of about one-tenth of the film thickness of the laser absorption layer (P). In this way, by reducing the film thickness of the peeling promotion layer (P2), the generated gas can properly pass through the peeling promotion layer (P2) and peel the second wafer (W2) from the peeling promotion layer (P2).

[0085] However, even if the film thickness of the peeling promotion layer (P2) is large and peeling occurs at the interface between the peeling promotion layer (P2) and the laser absorption layer (P), the second wafer (W2) is peeled from the laser absorption layer (P) through the peeling promotion layer (P2), so as shown in FIG. 16, a part of the second wafer (W2) does not remain on the surface of the laser absorption layer (P) after peeling. That is, the surface (W2a) of the second wafer (W2) is protected by this, and roughness of the peeling surface can be suppressed.

[0086] In addition, in the above example, a material with low adhesion to the second wafer (W2) (silicon) was used as the peeling promotion layer (P2), but the material used for the peeling promotion layer (P2) is not limited to this, and, for example, a material with a different coefficient of thermal expansion from the second wafer (W2) (silicon) may be used. In such a case, the amount of deformation caused by heat generated by irradiation of laser light (L) on the laser absorption layer (P) is different between the second wafer (W2) and the peeling promotion layer (P2), and thereby a shear force is generated at the interface between the second wafer (W2) and the peeling promotion layer (P2), so that the second wafer (W2) and the peeling promotion layer (P2) can be peeled.

[0087] In addition, in the above embodiment, the peeling of the second wafer (W2) and the peeling promotion layer (P2) is carried out by releasing the compressive stress accumulated as the peeling modification layer (M1) that is generated by the irradiation of laser light, but there is a risk that the polymer wafer (T) may bend due to the stress generated in this way. If the polymer wafer (T) bends in this way, it may be impossible to properly perform wafer processing. Therefore, in order to suppress the bending of the polymer wafer (T), the polymer wafer (T) may be pressed from above when the laser light (L) is irradiated onto the laser absorption layer (P).

[0088] For example, if the polymer wafer (T) is bent to deform into an upwardly convex shape, the center of the polymer wafer (T) may be pressed by the pressing member (200), as shown in FIG. 19. Specifically, in the peeling of the second wafer (W2), first, a laser irradiation processing, i.e., an unpeeled area (R1), is formed in advance at the center of the laser absorption layer (P), which is the pressing range by the pressing member (200). After the unpeeled area (R1) is formed, the unpeeled area (R1) is then pressed by the pressing member (200). After that, when the formation location of the unpeeled area (R1) reaches the outer edge of the laser absorption layer (P) while the unpeeled area (R1) is pressed by the pressing member (200), the sequential peeling of the second wafer (W2) is initiated. At this time, since the center of the polymerization wafer (T) is suppressed by the pressing member (200), bending of the polymerization wafer (T) is suppressed.

[0089] Additionally, the non-peeling region (R1) may be formed from the outer side in the radial direction toward the inner side. That is, first, the non-peeling region (R1) is formed from the outer periphery toward the center of the laser absorption layer (P). At this time, the outer periphery end, which is the starting position for the formation of the non-peeling region (R1), is determined to be slightly inward in the radial direction from the outer periphery end of the laser absorption layer (P), and stress release is not performed. After the non-peeling region (R1) is formed, the non-peeling region (R1) is pressed by the pressing member (200). Then, with the non-peeling region (R1) pressed by the pressing member (200), the formation position of the non-peeling region (R1) reaches the outer periphery end of the laser absorption layer (P). After that, sequential peeling is initiated by forming a starting point modification layer (M1s) on the outer side in the radial direction of the second wafer (W2). At this time, since the center of the polymerization wafer (T) is suppressed by the pressing member (200), bending of the polymerization wafer (T) is suppressed.

[0090] In addition, since the polymerization wafer (T) is rotated during the irradiation of the laser light (L), it is preferable that the end of the pressing member (200) be configured to be rotatable together with the polymerization wafer (T).

[0091] In addition, for example, if the polymer wafer (T) is bent to deform into a downward convex shape, the peripheral portion (We) of the polymer wafer (T) may be pressed by the pressing member (200), as shown in FIG. 20. Specifically, in the peeling of the second wafer (W2), first, a laser irradiation processing, i.e., a peeling area (R2), is formed in advance on the outer periphery of the laser absorption layer (P), which is the pressing area by the pressing member (200). After the peeling area (R2) is formed, the peeling area (R2) is pressed by the pressing member (200). Then, with the peeling area (R2) pressed by the pressing member (200), the formation of an unpeeled area (R1) in the center of the laser absorption layer (P) is initiated from the inner side in the radial direction toward the outer side. Then, when the formation area of ​​the unpeeled region (R1) reaches the peeled region (R2), sequential peeling of the second wafer (W2) is initiated. At this time, since the outer periphery of the polymerized wafer (T) is suppressed by the pressing member (200), bending of the polymerized wafer (T) is suppressed.

[0092] In addition, in the polymerization wafer (T) processed in the above embodiment, as shown in FIG. 21, a reflective film (R) may be provided between the laser absorption layer (P) and the device layer (D2). That is, the reflective film (R) is formed on the side opposite to the incident surface of the laser light (L) in the laser absorption layer (P). For the reflective film (R), a material having a high reflectivity to the laser light (L) and a high melting point, such as a metal film, is used. Also, the device layer (D2) is a layer that has a function and is different from the reflective film (R).

[0093] In this case, the laser light (L) emitted from the laser irradiation unit (110) passes through the second wafer (W2) and is almost entirely absorbed by the laser absorption layer (P). Even if there is any laser light (L) that could not be fully absorbed, it is reflected by the reflective film (R). As a result, the laser light (L) does not reach the device layer (D2), and damage to the device layer (D2) can be reliably suppressed.

[0094] In addition, the laser light (L) reflected from the reflective film (R) is absorbed by the laser absorption layer (P). Therefore, the peeling efficiency of the second wafer (W2) can be improved.

[0095] In addition, in the above embodiment, the case in which laser lift-off processing of a polymerized wafer (T), that is, transfer processing of a device layer (D2) on a first wafer (W1) is performed in the wafer processing system (1) has been described; however, as described above, edge trimming processing of a second wafer (W2) can be performed in the wafer processing system (1). Below, the case in which edge trimming of the second wafer (W2) is performed in the wafer processing system (1) will be described.

[0096] First, a polymerized wafer (T) is taken out by a wafer transport device (20) from a cassette (Ct) placed on a cassette placement stand (10) of an incoming / outgoing block (G1), transferred to a wafer transport device (40) via a transition device (30), and then transported to an internal laser irradiation device (70).

[0097] In the internal laser irradiation device (70), as shown in FIG. 22 (a), a laser light (L2) (YAG laser light) is irradiated into the interior of the second wafer (W2) to form a peripheral modification layer (M2) which serves as a starting point for removing the peripheral portion (We) in the edge trimming described later. From the peripheral modification layer (M2), a crack (C2) extends in the thickness direction of the second wafer (W2). The upper and lower portions of the crack (C2) are brought to reach, for example, the back surface (W2b) and the surface (W2a) of the second wafer (W2), respectively. The polymerized wafer (T) having the peripheral modification layer (M2) formed inside the second wafer (W2) is then transported to the interface laser irradiation device (80) by the wafer transport device (40).

[0098] In the interface laser irradiation device (80), the bonding strength between the laser absorption layer (P) and the second wafer (W2) in the peripheral portion (We) of the polymerized wafer (T), which is the target for removal of the second wafer (W2), is reduced. Specifically, as shown in FIG. 22 (b), a laser light (L) (CO2 laser) is irradiated onto the laser absorption layer (P), and a peeling modification layer (M1) (unpeeled region (R1)) is formed on the radial outer side of the peripheral modification layer (M2) formed by the internal laser irradiation device (70).

[0099] In addition, for the formation of the peeling modification layer (M1) (unpeeled region (R1)), the chuck (100) (polymer wafer (T)) is rotated by the rotation mechanism (103), and the chuck (100) is moved in the Y-axis direction by the movement mechanism (104). Then, the laser light (L) is irradiated from the inner side in the diameter direction toward the outer side with respect to the laser absorption layer (P), and as a result, is irradiated in a spiral shape from the inner side to the outer side.

[0100] As the formation of the peeling modified layer (M1) continues, when the formation location of the peeling modified layer (M1) reaches the vicinity of the end of the second wafer (W2), i.e., the boundary (Ad), serial peeling is initiated from the outer side in the radial direction of the laser absorption layer (P) toward the inner side, as shown in (c) of FIG. 22. Here, in this embodiment, since the peeling modified layer (M1) is formed only radially outward from the peripheral modified layer (M2) (crack (C2)), the peeling between the laser absorption layer (P) and the second wafer (W2) proceeds only at the peripheral portion (We), i.e., only radially outward from the peripheral modified layer (M2).

[0101] The polymerized wafer (T), in which the laser absorption layer (P) and the second wafer (W2) in the main part (We) have been peeled off, is then transported to the main part removal device (50) by the wafer transport device (40).

[0102] In the edge removal device (50), the edge portion (We) of the second wafer (W2) is removed (edge ​​trim) starting from the edge modification layer (M2) and the crack (C2) of the polymerized wafer (T), as shown in (d) of FIG. 22. Additionally, the edge trim method in the edge removal device (50) can be arbitrarily selected. At this time, in removing the edge portion (We), the bonding strength between the second wafer (W2) and the laser absorption layer (P) is reduced by the formation of the peeling modification layer (M1), so the removal of the edge portion (We) can be easily performed.

[0103] The polymerized wafer (T), from which the periphery (We) of the second wafer (W2) has been removed, is then transported to the cleaning device (60) by the wafer transport device (40). In the cleaning device (60), scrub cleaning of the polymerized wafer (T) is performed. Afterward, the polymerized wafer (T), having undergone all processing, is removed from the cleaning device (60) by the wafer transport device (40) and transported to the cassette (Ct) of the cassette placement table (10) by the wafer transport device (20) via the transition device (30). In this way, a series of wafer processing in the wafer processing system (1) is completed.

[0104] As described above, according to the technology of the present disclosure, the bonding strength between the second wafer (W2) and the laser absorption layer (P) at the periphery (We) in the laser irradiation device (80) for the interface can be reduced, and thereby, the periphery (We) can be appropriately removed, i.e., edge trimmed, in the periphery removal device (50).

[0105] Additionally, the processing sequence of the polymerized wafer (T) by the internal laser irradiation device (70) and the interface laser irradiation device (80) is not limited to the above embodiment, and after the peripheral portion (We) is peeled off in the interface laser irradiation device (80), the peripheral modification layer (M2) may be formed in the internal laser irradiation device (70).

[0106] The embodiments disclosed herein should be considered as illustrative and not limiting in all respects. The above embodiments may be omitted, substituted, or modified in various forms without departing from the scope and common knowledge of the appended claims. Explanation of the symbols delete

Claims

Claim 1 A substrate processing method for processing a polymerized substrate having a first substrate and a second substrate bonded together, wherein a laser absorption layer is formed on the second substrate, and a peeling modification layer is formed by irradiating a laser light in a pulse shape onto the laser absorption layer, and the laser light is irradiated in a pulse shape while forming the peeling modification layer so as not to overlap each other, and stress is accumulated inside the laser absorption layer, and the accumulated stress is sequentially released and the second substrate is peeled. Claim 2 A substrate processing method according to claim 1, wherein, when forming the peeling modification layer, peeling of the laser absorption layer and the second substrate does not occur. Claim 3 A substrate treatment method comprising forming a starting point modification layer that serves as a starting point for the sequential release of the stress in claim 1 or 2. Claim 4 A substrate processing method according to claim 3, wherein the starting point modification layer is formed inside the laser absorption layer at the end of the bonding region where the first substrate and the second substrate are bonded, and when forming the starting point modification layer, the stress generated by the formation of the starting point modification layer is released into an unbonded region which is a region outside the diameter direction of the bonding region, thereby causing delamination between the laser absorption layer and the second substrate, and the release of the sequential stress is initiated by releasing the stress accumulated by the formation of the delamination modification layer into the delamination region formed by the formation of the starting point modification layer. Claim 5 A substrate processing method according to claim 3, wherein, when forming the base point modification layer, delamination of the laser absorption layer and the second substrate is caused by irradiation with laser light, and the release of the sequential stress is initiated by releasing the stress accumulated by the formation of the delamination modification layer into the delamination area formed by the formation of the base point modification layer. Claim 6 A substrate processing method according to claim 4, wherein the above-mentioned starting point modification layer is formed radially outward from the above-mentioned peeling modification layer. Claim 7 A substrate processing method according to claim 1 or 2, comprising forming a peripheral modification layer along the boundary between the peripheral portion of the second substrate to be removed and the central portion of the second substrate, and forming the peeling modification layer radially outward from the peripheral modification layer. Claim 8 A substrate treatment method according to claim 1 or 2, wherein the peeling modified layer is not formed in the center of the laser absorption layer. Claim 9 A substrate processing method according to claim 1 or 2, wherein at least one of the formation location of the peeling modified layer and the irradiation type of the laser light during the formation of the peeling modified layer increases the formation area of ​​the peeling modified layer relative to the laser absorption layer. Claim 10 A substrate processing method according to claim 1 or 2, wherein a peel-promoting layer that promotes peeling of the second substrate is further formed between the second substrate and the laser absorption layer. Claim 11 A substrate processing method according to claim 1 or 2, wherein when the laser light is irradiated onto the laser absorption layer, a pulse-shaped laser light is emitted from a laser oscillator toward an optical element, and the frequency of the laser light in the optical element is adjusted. Claim 12 A substrate processing method according to claim 11, wherein the frequency of the laser light from the laser oscillator is the highest frequency controllable by the optical element. Claim 13 A substrate processing method according to claim 11, wherein when the laser light is irradiated onto the laser absorption layer, the laser light from the laser oscillator is attenuated in the attenuator. Claim 14 A substrate processing apparatus for processing a polymerized substrate having a first substrate and a second substrate bonded together, wherein a laser absorption layer is formed on the second substrate, and the apparatus comprises a laser irradiation unit that irradiates laser light in a pulse shape onto the laser absorption layer of the second substrate, and a control unit that controls the operation of the laser irradiation unit, wherein the control unit controls the operation of the laser irradiation unit to form a peeling modification layer by irradiating the laser light, irradiates the laser light in a pulse shape while forming the peeling modification layer without overlapping each other, accumulates stress inside the laser absorption layer, and then peels the second substrate by the sequential release of the accumulated stress. Claim 15 In claim 14, the control unit controls the output of the laser light so as not to cause delamination of the laser absorption layer and the second substrate during the formation of the peeling modification layer, a substrate processing device. Claim 16 A substrate processing apparatus according to claim 14 or 15, wherein the control unit controls the operation of the laser irradiation unit to form a starting point modification layer that serves as a starting point for the sequential release of the stress. Claim 17 A substrate processing apparatus according to claim 16, wherein the control unit controls the operation of the laser irradiation unit such that the control unit forms the starting point modification layer inside the laser absorption layer at the end of the bonding region where the first substrate and the second substrate are bonded, and when forming the starting point modification layer, the stress generated by the formation of the starting point modification layer is released to an unbonded region which is a region outside the diameter direction of the bonding region, thereby causing delamination between the laser absorption layer and the second substrate, and the release of the sequential stress is initiated by releasing the stress accumulated by the formation of the delamination modification layer to the delamination region formed by the formation of the starting point modification layer. Claim 18 A substrate processing apparatus according to claim 16, wherein the control unit controls the output of the laser light so that, when forming the starting point modification layer, peeling of the laser absorption layer and the second substrate occurs by irradiating the laser light, and also controls the operation of the laser irradiation unit so as to initiate the release of the chain stress by releasing the stress accumulated by the formation of the peeling modification layer into the peeling area formed by the formation of the starting point modification layer. Claim 19 In claim 17, the control unit controls the operation of the laser irradiation unit so as to form the origin modification layer radially outward from the peeling modification layer. Claim 20 A substrate processing apparatus according to claim 14 or 15, comprising a second laser irradiation unit that forms a peripheral modification layer along the boundary between the peripheral portion of the second substrate to be removed and the central portion of the second substrate, wherein the control unit controls the operation of the laser irradiation unit so as to form the peeling modification layer radially outward from the peripheral modification layer. Claim 21 A substrate processing apparatus according to claim 14 or 15, wherein the control unit controls the operation of the laser irradiation unit so as not to form the peeling modified layer at the center of the laser absorption layer. Claim 22 A substrate processing apparatus according to claim 14 or 15, wherein the control unit controls at least one of the formation location of the peeling modification layer and the irradiation type of the laser light during the formation of the peeling modification layer so as to increase the formation area of ​​the peeling modification layer with respect to the laser absorption layer. Claim 23 A substrate processing apparatus according to claim 14 or 15, wherein a peel-promoting layer that promotes peeling of the second substrate is further formed between the second substrate and the laser absorption layer. Claim 24 A substrate processing apparatus according to claim 14 or 15, comprising a control unit for controlling the laser irradiation unit, wherein the laser irradiation unit comprises a laser oscillator that emits laser light in a pulse shape and an optical element that deflects the laser light from the laser oscillator in a different direction, and wherein the control unit controls the optical element to adjust the frequency of the laser light irradiated onto the laser absorption layer. Claim 25 A substrate processing apparatus according to claim 24, wherein the frequency of the laser light from the laser oscillator is the highest frequency controllable by the optical element. Claim 26 In claim 24, the laser irradiation unit is a substrate processing device having an attenuator that attenuates laser light from the laser oscillator.

Images