Substrate processing method, substrate processing apparatus, program, and computer storage medium

Abstract

To appropriately peel a second substrate off from a first substrate in a laminated substrate in which the first substrate and the second substrate are bonded together.SOLUTION: A substrate processing method for processing a laminated substrate formed by bonding a first substrate and a second substrate, the second substrate has a peeling-promoting layer and a laser absorbing layer stacked in this order from the second substrate side, the substrate processing method including radiating laser light from the second substrate side to the laser absorbing layer to generate stress at an interface between the laser absorbing layer and the peeling-promoting layer, and peeling the second substrate from the first substrate along a boundary between the laser absorbing layer and the peeling-promoting layer.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a substrate processing method, a substrate processing apparatus, a program, and a computer storage medium. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a semiconductor device. In this method, CO is injected from the back surface of a semiconductor substrate. 2 The method includes a heating step of locally heating the peeling oxide film by irradiating a laser, and a transfer step of causing peeling in the peeling oxide film and / or at the interface between the peeling oxide film and the semiconductor substrate, thereby transferring the semiconductor element to a destination substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japan Patent Publication No. 2007-220749 Summary of the Invention [Problem to be solved by the invention]

[0004] The technique according to the present disclosure appropriately peels the second substrate from the first substrate in a laminated substrate in which a first substrate and a second substrate are bonded together. [Means for solving the problem]

[0005] One aspect of the present disclosure is a substrate processing method for processing a polymerized substrate formed by bonding a first substrate and a second substrate, the second substrate having a peeling-promoting layer and a laser absorbing layer stacked in this order from the second substrate side, the substrate processing method including: irradiating laser light from the second substrate side to the laser absorbing layer to generate stress at an interface between the laser absorbing layer and the peeling-promoting layer; and peeling the second substrate from the first substrate along a boundary between the laser absorbing layer and the peeling-promoting layer. Effect of the Invention

[0006] According to the present disclosure, in a laminated substrate in which a first substrate and a second substrate are bonded together, the second substrate can be appropriately peeled off from the first substrate. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a side view illustrating an example of an overlapping wafer being processed in a wafer processing system. [Diagram 2] 1 is a plan view illustrating a schematic configuration of a wafer processing system. [Diagram 3] FIG. 2 is a side view showing an outline of the configuration of an interface laser irradiation device. [Figure 4] FIG. 2 is a plan view showing an outline of the configuration of an interface laser irradiation device. [Diagram 5] 4A to 4C are explanatory diagrams showing a state in which a release improving layer according to the present embodiment is formed. [Figure 6] 4 is a plan view showing an example of forming a release improving layer according to the present embodiment. FIG. [Figure 7] 4 is an explanatory diagram showing a gas flow inside the overlapping wafer in the wafer processing according to the embodiment. FIG. [Figure 8] FIG. 11 is a plan view showing another example of forming a release improving layer according to the present embodiment. [Figure 9] FIG. 4 is an explanatory diagram showing how the second wafer is peeled off in the present embodiment. [Figure 10] FIG. 4 is an explanatory diagram showing how the second wafer is peeled off in the present embodiment. [Figure 11] FIG. 11 is an explanatory view showing how the second wafer is pressed. [Figure 12] FIG. 11 is an explanatory view showing how the second wafer is pressed. [Figure 13] FIG. 11 is a side view showing an outline of a configuration of an overlapping wafer according to another embodiment. [Figure 14] FIG. 4 is an explanatory diagram showing the flow of edge trimming processing according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In recent years, in the manufacturing process of LEDs, a so-called laser lift-off has been performed in which a GaN (gallium nitride) compound crystal layer (material layer) is peeled off from a sapphire substrate using laser light. The reason why laser lift-off is performed in this way is that the sapphire substrate is transparent to short-wavelength laser light (e.g. UV light), so that short-wavelength laser light with high absorption rate can be used for the laser absorption layer, and there is a wide range of choices for laser light.

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

[0010] In general, for example, CO 2 The laser can use laser light with a wavelength in the FIR. In the method described in the above-mentioned Patent Document 1, CO is applied to the peeled oxide film as a laser absorption layer. 2 By irradiating the laser, peeling occurs at the interface between the peeled oxide film and the substrate.

[0011] However, the inventors have made extensive studies and found that the laser lift-off method may not properly separate the laser absorbing layer from the substrate, i.e., may not properly transfer the laser layer. Specifically, if there is a region in the surface of the laser absorbing layer where the laser light is not irradiated and the bonding strength between the laser absorbing layer and the substrate is not reduced, the wafer W may be peeled off from the inside in the region where the laser light is not irradiated, and a part of the wafer W (a silicon piece) may be transferred together with the device layer to the surface of the laser absorbing layer after the transfer process.

[0012] The technology disclosed herein appropriately peels the second substrate from the first substrate in a laminated substrate in which the first substrate and the second substrate are bonded together. Hereinafter, a wafer processing system as a substrate processing apparatus according to the present embodiment and a wafer processing method as a substrate processing method will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are denoted by the same reference numerals to avoid redundant description.

[0013] As shown in Fig. 1, a laminated wafer T as a laminated 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, a surface on the side bonded to the second wafer W2 is referred to as a front surface W1a, and a surface opposite to the front surface W1a is referred to as a back surface W1b. Similarly, in the second wafer W2, a surface on the side bonded to the first wafer W1 is referred to as a front surface W2a, and a surface opposite to the front surface W2a is referred to as a back surface W2b.

[0014] The first wafer W1 is a semiconductor wafer such as a silicon substrate. A device layer D1 including a plurality of devices is formed on a surface W1a of the first wafer W1. A surface film F1 is further formed on the device layer D1, and the first wafer W1 is bonded to a second wafer W2 via the surface film F1. The surface film F1 can be, for example, an oxide film (SiO 2 Examples of the material include a silicon oxide film (SiO 2 film, TEOS film), a silicon carbide film, a silicon carbide film, an adhesive, etc. Note that there are cases where the device layer D1 and the surface film F1 are not formed on the surface W1a.

[0015] The second wafer W2 is also a semiconductor wafer such as a silicon substrate. A peeling promoting layer P2, a laser absorbing layer P, a device layer D2, and a surface film F2 are formed on the surface W2a of the second wafer W2 in this order from the surface W2a side, and the second wafer W2 is bonded to the first wafer W1 via the surface film F2. The device layer D2 and the surface film F2 are similar to the device layer D1 and the surface film F1 of the first wafer W1, respectively. The laser absorbing layer P is a layer formed by absorbing a laser beam (e.g., CO 2Laser) can be absorbed, for example, oxide film (SiO 2 Examples of the peeling-promoting layer P2 include a TEOS film and the like. The peeling-promoting layer P2 is formed to facilitate peeling (transferring) of the second wafer W2 from the first wafer W1, and is made of a material having lower adhesion to the second wafer W2 (silicon) than to the laser absorbing layer P, such as silicon nitride (SiN). Note that the peeling-promoting layer P2, the laser absorbing layer P, the device layer D2, and the surface film F2 may not be formed on the surface W2a. In this case, the peeling-promoting layer P2 and the laser absorbing layer P are 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 side.

[0016] The peripheral edge We of the second wafer W2 is chamfered, and the thickness of the cross section of the peripheral edge We decreases toward the tip. In the manufacturing process of semiconductor devices, the back surface of the second wafer W2 thus formed may be removed to thin it, and this thinning process may result in the peripheral edge We having a sharp pointed shape (so-called knife edge shape). If this occurs, chipping may occur at the peripheral edge We of the second wafer W2, and the second wafer W2 may be damaged. Therefore, before this thinning process, edge trimming, which will be described later, may be performed to remove the peripheral edge We of the second wafer W2 in advance. The peripheral edge We is the portion removed in this edge trimming, and is, for example, in the range of 0.5 mm to 3 mm in the radial direction from the outer end of the second wafer W2.

[0017] In the wafer processing system 1 according to this embodiment, which will be described later, the aforementioned laser lift-off process as wafer processing, i.e., the transfer process of the device layer D2 to the first wafer W1 side, or the aforementioned edge trim process as wafer processing, i.e., the removal process of the peripheral portion We of the second wafer W2, is performed.

[0018] 2, the wafer processing system 1 has a configuration in which a load / unload block G1, a transport block G2, and a processing block G3 are integrally connected. The load / unload block G1, the transport block G2, and the processing block G3 are arranged in this order from the negative side of the X-axis.

[0019] The carry-in / out block G1 carries in and out cassettes Ct, Cw1, and Cw2 capable of accommodating a plurality of overlapped wafers T, a plurality of first wafers W1, and a plurality of second wafers W2, for example, between the outside and the inside of the device. The carry-in / out block G1 is provided with a cassette mounting table 10. In the illustrated example, the cassette mounting table 10 can freely mount a plurality of cassettes Ct, Cw1, and Cw2, for example, three cassettes Ct, Cw1, and Cw2, in a line in the Y-axis direction. The number of cassettes Ct, Cw1, and Cw2 mounted on the cassette mounting table 10 is not limited to this embodiment and can be determined arbitrarily.

[0020] In the transport block G2, a wafer transport device 20 is provided adjacent to the cassette mounting table 10 on the X-axis positive side of the cassette mounting table 10. The wafer transport device 20 is configured to be movable on a transport path 21 extending in the Y-axis direction. The wafer transport device 20 has, for example, two transport arms 22, 22 that hold and transport the overlapped wafer T, the first wafer W1, and the second wafer W2. Each transport arm 22 is configured to be movable in the horizontal direction, the vertical direction, around the horizontal axis, and around the vertical axis. The configuration of the transport arm 22 is not limited to this embodiment, and may have any configuration. The wafer transport device 20 is configured to be able to transport the overlapped wafer T, the first wafer W1, and the second wafer W2 to the cassettes Ct, Cw1, and Cw2 of the cassette mounting table 10 and a transition device 30 described later.

[0021] In the transfer block G2, a transition device 30 for transferring the overlapped wafer T, the first wafer W1, and the second wafer W2 is provided adjacent to the wafer transfer device 20 on the positive side of the X-axis of the wafer transfer device 20.

[0022] The processing block G3 includes a wafer transfer device 40, an edge removing device 50, a cleaning device 60, an internal laser irradiation device 70, and an interface laser irradiation device 80.

[0023] The wafer transport device 40 is configured to be movable on a transport path 41 extending in the X-axis direction. The wafer transport device 40 has, for example, two transport arms 42, 42 that hold and transport the overlapped 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. The configuration of the transport arm 42 is not limited to this embodiment, and may have any configuration. The wafer transport device 40 is configured to be able to transport the overlapped 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.

[0024] The edge removal device 50 is provided on the Y-axis positive side of the wafer transport device 40, and removes the edge We of the second wafer W2, i.e., performs edge trim processing. The cleaning device 60 is provided on the Y-axis negative side of the wafer transport device 40, and cleans the laminated wafer T after peeling or after removal of the edge We. The internal laser irradiation device 70 as a second laser irradiation section is provided on the Y-axis positive side of the wafer transport device 40, and irradiates the inside of the second wafer W2 with laser light (internal laser light, e.g., YAG laser) to form a later-described edge modified layer M2 that serves as a base point for peeling off the edge We. The interface laser irradiation device 80 is provided on the Y-axis negative side of the wafer transport device 40, and irradiates the laser absorption layer P formed on the surface W2a of the second wafer W2 with laser light (interface laser light, e.g., CO 2 The structure of the interface laser irradiation device 80 will be described later.

[0025] The above-described 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 the laminated wafer T in the wafer processing system 1. The program storage unit also stores a program for controlling the operation of a drive system such as the above-described various processing devices and transport device to realize wafer processing in the wafer processing system 1, which will be described later. The above-described program may be recorded in a computer-readable storage medium H and installed in the control device 90 from the storage medium H.

[0026] The wafer processing system 1 is configured as described above, and can perform the above-mentioned laser lift-off process of the laminated wafer T, i.e., the transfer process of the device layer D2 to the first wafer W1, and the above-mentioned edge trim process of the second wafer W2, in the wafer processing system 1. Note that, for example, when the edge trim process of the second wafer W2 is not performed in the wafer processing system 1, the peripheral removal device 50 and the internal laser irradiation device 70 can be omitted.

[0027] In addition, in this embodiment, the peeling of the second wafer W2 from the first wafer W1 is performed in an interface laser irradiation device 80 as described below, but the wafer processing system 1 may be further provided with a separate peeling device as a peeling section.

[0028] Next, the interface laser irradiation device 80 will be described.

[0029] 3 and 4, the interface laser irradiation device 80 has a chuck 100 that holds the overlapped wafer T on its upper surface. The chuck 100 suction-holds a part or the entire back surface W1b of the first wafer W1. The chuck 100 is provided with lifting pins (not shown) for transferring the overlapped wafer T to and from the transfer arm 42. The lifting pins are inserted through through-holes (not shown) formed through the chuck 100 so as to be able to move up and down, and support and lift the overlapped wafer T from below.

[0030] The chuck 100 is supported by a slider table 102 via an air bearing 101. A rotation mechanism 103 is provided on the lower surface side of the slider table 102. The rotation mechanism 103 incorporates, for example, a motor as a drive source. The chuck 100 is configured to be rotatable about a θ-axis (vertical axis) via the air bearing 101 by the rotation mechanism 103. The slider table 102 is configured to be movable along a rail 105 provided on a base 106 and extending in the Y-axis direction by a movement mechanism 104 provided on the lower surface side of the chuck 100. The drive source of the movement mechanism 104 is not particularly limited, but for example, a linear motor is used.

[0031] A laser head 110 serving as a laser irradiation unit is provided above the chuck 100. The laser head 110 has a lens 111. The lens 111 is a cylindrical member provided on the lower surface of the laser head 110, and irradiates a laser beam onto the overlapped wafer T held by the chuck 100. In this embodiment, the laser beam is a pulsed CO 2 The laser light emitted from the laser head 110 passes through the second wafer W2 and is irradiated onto the laser absorption layer P. 2 The wavelength of the laser light is, for example, 8.9 μm to 11 μm. The laser head 110 is configured to be movable up and down by an elevation mechanism (not shown). The light source of the laser light is provided at a position outside the laser head 110 and away from it.

[0032] Moreover, above the chuck 100, a transfer pad 120 is provided as a peeling unit having an adsorption surface for adsorbing and holding the back surface W2b of the second wafer W2 on its lower surface. The transfer pad 120 is configured to be freely raised and lowered by a lifting mechanism (not shown). The transfer pad 120 transfers the second wafer W2 between the chuck 100 and the transfer arm 42. Specifically, after the chuck 100 is moved to below the transfer pad 120 (a transfer position with the transfer arm 42), the transfer pad 120 is lowered to adsorb and hold the back surface W2b of the second wafer W2, and then the transfer pad 120 is raised again to peel the second wafer W2 from the first wafer W1. The peeled second wafer W2 is transferred from the transfer pad 120 to the transfer arm 42 and carried out of the interface laser irradiation device 80. The transfer pad 120 may be configured to flip the front and back surfaces of the wafer by a flipping mechanism (not shown).

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

[0034] First, a cassette Ct storing a plurality of overlapped wafers T is placed on the cassette mounting table 10 of the carry-in / out block G1. Next, the overlapped wafers T in the cassette Ct are removed by the wafer transfer device 20. The overlapped wafers T removed from the cassette Ct are transferred to the wafer transfer device 40 via the transition device 30, and then transferred to the interface laser irradiation device 80. In the interface laser irradiation device 80, the second wafer W2 is peeled off from the first wafer W1 (laser lift-off process).

[0035] Specifically, the overlapped wafer T, which is attracted to and held on the chuck 100 via the lift pins of the transfer arm 42, is first moved to a processing position by the moving mechanism 104. This processing position is a position where the laser head 110 can irradiate the overlapped wafer T (laser absorbing layer P) with laser light.

[0036] Next, as shown in FIGS. 5 and 6, a laser beam L(CO 2 The laser light) is irradiated in a pulsed manner. At this time, the laser light L passes through the second wafer W2 and the peeling promoting layer P2 from the back surface W2b side of the second wafer W2, and is absorbed in the laser absorbing layer P. Then, stress is generated inside the laser absorbing layer P that absorbs the laser light L, as shown in FIG. 7(a). Hereinafter, the stress accumulation layer that is generated and formed by the irradiation of the laser light and serves as the base point of peeling of the second wafer W2 (the base point of transfer of the device layer D2) may be referred to as the "peeling modified layer M1". Note that the laser light L irradiated to the laser absorbing layer P has almost all of its energy absorbed by the formation of the peeling modified layer M1, and does not reach the device layer D2. Therefore, it is possible to suppress damage to the device layer D2.

[0037] Here, the laser light L irradiated to the laser absorbing layer P is controlled to an output that does not cause the peeling promotion layer P2 and the laser absorbing layer P to peel off due to stress generated by the irradiation of the laser light L.

[0038] In this way, the laser light L is irradiated to prevent the peeling of the peeling promoting layer P2 and the laser absorbing layer P, and the stress generated is prevented from escaping, so that the stress accumulates inside the laser absorbing layer P, forming the peeling modified layer M1. More specifically, for example, the laser absorbing layer P is gasified by the irradiation of the laser light, and the gas generated as described above is prevented from escaping, so that the compressive stress accumulates as the peeling modified layer M1. Also, for example, heat is generated in the laser absorbing layer P by the absorption of the laser light, and shear stress accumulates as the peeling modified layer M1 due to the difference in thermal expansion coefficient between the peeling promoting layer P2 and the laser absorbing layer P.

[0039] The stress generated by the irradiation of the laser light L usually remains at the irradiation position of the laser light L (inside the laser absorbing layer P) as described above, forming the peeling modified layer M1. However, in this embodiment, the peeling promoting layer P2 is formed between the surface W2a of the second wafer W2 and the laser absorbing layer P, and the adhesion between the peeling promoting layer P2 and the second wafer W2 is smaller than the adhesion between the peeling promoting layer P2 and the laser absorbing layer P. Therefore, as shown in FIG. 7(b), the stress generated inside the laser absorbing layer P passes through the peeling promoting layer P2 and accumulates at the interface between the peeling promoting layer P2 and the second wafer W2. In other words, the stress generated by the irradiation of the laser light L moves to the interface between the peeling promoting layer P2 and the second wafer W2 where it can stay more stably and accumulates there. And when the stress accumulates at the interface between the peeling promoting layer P2 and the second wafer W2 in this way, the bonding strength between the peeling promoting layer P2 and the second wafer W2 decreases.

[0040] In this embodiment, the laser absorbing layer P is irradiated with the laser light L, that is, the peeling of the peeling promoting layer P2 and the second wafer W2 is performed on the entire surface of the laser absorbing layer P in plan view. Specifically, when the laser absorbing layer P is irradiated with the laser light L, the chuck 100 (superimposed wafer T) is rotated by the rotating mechanism 103, and the chuck 100 is moved in the Y-axis direction by the moving mechanism 104. Then, the laser light L is irradiated to the laser absorbing layer P, for example, from the outside to the inside in the radial direction, and as a result, the entire surface of the surface of the laser absorbing layer P is irradiated in a spiral shape from the outside to the inside. Note that the black arrow shown in FIG. 6 indicates the rotation direction of the chuck 100. Note that the formation direction of the peeling modified layer M1 may be from the inside to the outside in the radial direction.

[0041] Here, the interval between adjacent peeling modified layers M1, in other words, the pulse interval (frequency) of the laser light L, is controlled to an interval that does not cause peeling in the adjacent peeling modified layers M1 due to the impact generated during the formation of the peeling modified layers M1. Specifically, for example, it is preferable that adjacent peeling modified layers M1 are formed so as not to overlap each other in a plan view. In addition, at this time, it is preferable that adjacent peeling modified layers M1 are formed close to each other.

[0042] 8, the laser light L may be irradiated in a concentric ring shape on the laser absorption layer P. However, in this case, since the rotation of the chuck 100 and the Y direction of the chuck 100 are alternately performed, it is better to irradiate the laser light L in a spiral shape as described above, because it is possible to shorten the irradiation time and improve the throughput.

[0043] In addition, in this embodiment, when irradiating the laser absorption layer P with the laser light L, the chuck 100 is rotated, but the laser head 110 may be moved and rotated relatively to the chuck 100. In addition, the chuck 100 is moved in the Y-axis direction, but the laser head 110 may be moved in the Y-axis direction.

[0044] When the laser light L is irradiated onto the in-plane front surface of the laser absorption layer P, the chuck 100 is then moved to a delivery position below the transfer pad 120 by the moving mechanism 104. At the delivery position, the back surface W2b of the second wafer W2 is adsorbed and held by the transfer pad 120 as shown in FIG. 9(a), and then the transfer pad 120 is raised as shown in FIG. 9(b) to peel off the second wafer W2 from the peeling promotion layer P2 (first wafer W1). As a result, the device layer D2 formed on the surface of the second wafer W2 is transferred to the first wafer W1. At this time, as described above, stress generated by the irradiation of the laser light is accumulated at the interface between the peeling promotion layer P2 and the second wafer W2, and the bonding strength is reduced, so that the second wafer W2 can be peeled off from the peeling promotion layer P2 without applying a large load.

[0045] At this time, the peeling modified layers M1 are formed so as not to overlap each other as described above, but the stress accumulated by the formation of the peeling modified layers M1 is released to the outside when peeling occurs between the second wafer W2 and the peeling promotion layer P2 at the formation position of the peeling modified layers M1. In this embodiment, the peeling modified layers M1 are formed close to each other as described above, so that when peeling occurs at the formation position of the adjacently formed peeling modified layers M1, that is, when the stress is released to the outside at the adjacent position, it is released in a chain reaction. That is, when a part of the interface between the peeling promotion layer P2 and the second wafer W2 is peeled off by raising the transfer pad 120, the entire surface of the second wafer W2 is peeled off in a chain reaction starting from the peeling location. That is, the second wafer W2 can be peeled off more appropriately from the peeling promotion layer P2 without applying a large load.

[0046] Incidentally, as shown in FIG. 1, the laser absorption layer P irradiated with the laser light L may have a region (unpeeled region R1) where the laser light L is not irradiated due to the relationship between the frequency of the laser light L and the rotation speed of the chuck 100, and the like, where the peeling promotion layer P2 and the second wafer W2 are not peeled off. However, according to this embodiment, since the peeling promotion layer P2 is formed of a material that has low adhesion to the second wafer W2 (silicon), peeling of the peeling promotion layer P2 and the second wafer W2 can be easily performed even when the unpeeled region R1 is formed. And, since the peeling promotion layer P2 and the second wafer W2 are appropriately peeled off in this way, it is possible to appropriately suppress the transfer of a part (silicon piece) of the second wafer W2 to the surface of the peeling promotion layer P2 after the second wafer W2 is peeled off. This also suppresses damage to the second wafer W2 after peeling.

[0047] In addition, when the peeling-promoting layer P2 and the second wafer W2 are appropriately peeled off at the interface, the stress generated by the irradiation of the laser light must pass through the peeling-promoting layer P2. Specifically, for example, when the laser absorbing layer P is gasified, the generated gas must pass through the laser absorbing layer P. Also, for example, when the peeling-promoting layer P2 and the second wafer W2 are peeled off due to the difference in thermal expansion coefficient, the heat generated by the irradiation of the laser light must be appropriately transferred to the interface between the peeling-promoting layer P2 and the second wafer W2. However, when the thickness of the peeling-promoting layer P2 is large, the generated stress may not properly pass through the peeling-promoting layer P2 and may remain at the interface between the peeling-promoting layer P2 and the laser absorbing layer P. Therefore, in order to appropriately peel off the peeling-promoting layer P2 and the second wafer W2 at the interface, the thickness of the peeling-promoting layer P2 is preferably thinner than the laser absorbing layer P, specifically, for example, about one tenth of the thickness of the laser absorbing layer P. By reducing the thickness of the peeling-promoting layer P2 in this way, the generated stress can be properly transmitted through the peeling-promoting layer P2, and the bonding strength of the peeling-promoting layer P2 to the second wafer W2 can be reduced. In other words, the second wafer W2 can be properly peeled off from the peeling-promoting layer P2.

[0048] However, even if the thickness of the peeling-promoting layer P2 becomes large and the generated stress does not properly pass through the peeling-promoting layer P2 and remains at the interface between the peeling-promoting layer P2 and the laser absorbing layer P, the peeling-promoting layer P2 can act as a protective film for the second wafer W2. That is, when the second wafer W2 is peeled from the inside, it is possible to properly suppress the transfer of silicon pieces together with the device layer D2 to the interface after peeling.

[0049] Specifically, a peeling modified layer M1 is formed by stress generated at the interface between the peeling promoting layer P2 and the laser absorbing layer P, and if stress remains at the interface, the second wafer W2 is peeled off from the first wafer W1 with the peeling promoting layer P2 and the laser absorbing layer P as the boundary, as shown in Fig. 10. At this time, since the second wafer W2 is peeled off from the laser absorbing layer P via the peeling promoting layer P2, the second wafer W2 does not remain at the peeling interface. That is, this protects the surface W2a of the second wafer W2, and suppresses damage to the peeled surface.

[0050] The second wafer W2 peeled off from the first wafer W1 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 mounting table 10. Note that the surface W2a of the second wafer W2 transferred out of the interface laser irradiation device 80 may be cleaned in the cleaning device 60 before being transferred to the cassette Cw2.

[0051] Meanwhile, the first wafer W1 held by the chuck 100 is transferred to the transfer arm 42 of the wafer transfer device 40 via the lift pins, and transferred to the cleaning device 60. In the cleaning device 60, the surface of the peeling promotion layer P2, which is the peeling surface, is scrubbed and cleaned. In the cleaning device 60, the back surface W1b of the first wafer W1 may be cleaned together with the surface of the peeling promotion layer P2.

[0052] Thereafter, the first wafer W1, which has been subjected to all processes related to the transfer of the device layer D2 onto the first wafer W1, is transferred by the wafer transfer device 20 to the cassette Cw1 on the cassette mounting table 10 via the transition device 30. In this manner, a series of wafer processing steps in the wafer processing system 1 is completed.

[0053] According to the above embodiment, since the peeling promoting layer P2 is formed between the second wafer W2 and the laser absorbing layer P, the second wafer W2 can be appropriately peeled off from the first wafer W1, that is, the transfer process of the device layer D2 can be appropriately performed. Specifically, the stress generated in the laser absorbing layer P by the irradiation of the laser light moves to the boundary between the second wafer W2 and the peeling promoting layer P2, and the bonding strength at the boundary between the second wafer W2 and the peeling promoting layer P2 is reduced, so that the second wafer W2 and the peeling promoting layer P2 can be appropriately peeled off. In addition, since the peeling promoting layer P2 is formed of a material (e.g., SiN) that has low adhesion to the second wafer W2, the peeling promoting layer P2 can be more appropriately peeled off from the second wafer W2.

[0054] In the above embodiment, a material having low adhesion to the second wafer W2 (silicon) is used as the peeling promoting layer P2, but the material used for the peeling promoting layer P2 is not limited to this, and for example, a material having a thermal expansion coefficient different from that of the second wafer W2 (silicon) may be used. In such a case, the amount of deformation caused by heat generated by the irradiation of the laser light L to the laser absorption layer P differs between the second wafer W2 and the peeling promoting layer P2, and a shear force is generated at the interface between the second wafer W2 and the peeling promoting layer P2, and the second wafer W2 and the peeling promoting layer P2 can be peeled off. In particular, when a shear stress is generated and accumulated as the peeling modified layer M1 at the interface between the second wafer W2 and the peeling promoting layer P2 as described above, the second wafer W2 and the peeling promoting layer P2 can be peeled off more appropriately by using a material having a thermal expansion coefficient different from that of the peeling promoting layer P2.

[0055] In the above embodiment, the second wafer W2 is peeled off from the peeling promoting layer P2 by irradiation with the laser light L, but when the second wafer W2 is peeled off, warping may occur in the overlapped wafer T. If warping occurs in the overlapped wafer T, there is a risk that the wafer processing system 1 will not be able to perform the wafer processing appropriately. In order to suppress warping of the overlapped wafer T, the overlapped wafer T may be pressed from above when the laser absorbing layer P is irradiated with the laser light L.

[0056] For example, when the overlapped wafer T is warped so as to be deformed into an upward convex shape, the center of the overlapped wafer T may be pressed by a pressing member 200 as shown in FIG. 11. Specifically, when peeling off the second wafer W2, first, a peeled modified layer M1 is formed in advance in the center of the laser absorbing layer P, which is the pressing range by the pressing member 200. The direction of formation of the peeled modified layer M1 in the radial direction is not particularly limited. After the peeled modified layer M1 is formed in the center of the laser absorbing layer P, the center of the overlapped wafer T on which the peeled modified layer M1 is formed is pressed by the pressing member 200. Then, with the center pressed by the pressing member 200, a peeled modified layer M1 is formed on the outer periphery of the laser absorbing layer P, and then the second wafer W2 is peeled off. At this time, since the center of the overlapped wafer T is pressed by the pressing member 200, the formation of the peeled and modified layer M1 on the outer periphery of the laser absorption layer P and the occurrence of warping of the overlapped wafer T during peeling of the second wafer W2 are suppressed.

[0057] In addition, since the overlapped wafer T is rotated when the laser light L is irradiated, it is preferable that the end portion of the pressing member 200 is configured to be rotatable together with the overlapped wafer T.

[0058] Also, for example, when warpage occurs such that the overlapped wafer T is deformed into a downward convex shape, the peripheral portion We of the overlapped wafer T may be pressed by a pressing member 200 as shown in FIG. 12. Specifically, when peeling off the second wafer W2, first, a peeled modified layer M1 is formed in advance on the outer periphery of the laser absorbing layer P, which is the pressing range by the pressing member 200. When the peeled modified layer M1 is formed on the outer periphery of the laser absorbing layer P, the outer periphery of the overlapped wafer T on which the peeled modified layer M1 is formed is then pressed by the pressing member 200. Then, in a state in which the outer periphery is pressed by the pressing member 200, the peeled modified layer M1 is formed on the center of the laser absorbing layer P, and then the second wafer W2 is peeled off. At this time, since the outer periphery of the overlapped wafer T is pressed by the pressing member 200, warpage of the overlapped wafer T is suppressed when the peeled modified layer M1 is formed on the center of the laser absorbing layer P and the second wafer W2 is peeled off.

[0059] In the overlapped wafer T processed in the above embodiment, a reflective film R may be provided between the laser absorption layer P and the device layer D2 as shown in FIG. 13. That is, the reflective film R is formed on the surface of the laser absorption layer P opposite to the incident surface of the laser light L. The reflective film R is made of a material having a high reflectance to the laser light L and a high melting point, such as a metal film. The device layer D2 is a layer having a function and is different from the reflective film R.

[0060] In this case, the laser light L emitted from the laser head 110 passes through the second wafer W2 and is almost entirely absorbed in the laser absorption layer P, but even if there is laser light L that has not been 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.

[0061] Moreover, the laser light L reflected by the reflective film R is absorbed by the laser absorption layer P. Therefore, the peeling efficiency of the second wafer W2 can be improved.

[0062] In the above embodiment, the laser lift-off process of the laminated wafer T, i.e., the transfer process of the device layer D2 onto the first wafer W1, is performed in the wafer processing system 1. However, as described above, the edge trim process of the second wafer W2 can be performed in the wafer processing system 1. Hereinafter, the case where the edge trim of the second wafer W2 is performed in the wafer processing system 1 will be described.

[0063] First, the overlapped wafer T is removed by the wafer transport device 20 from the cassette Ct placed on the cassette mounting table 10 of the load / unload block G1, and then transferred to the wafer transport device 40 via the transition device 30, and then transported to the internal laser irradiation device 70.

[0064] In the internal laser irradiation device 70, as shown in FIG. 14(a), a laser beam L2 (YAG laser beam) is irradiated to the inside of the second wafer W2 to form a peripheral modified layer M2 that serves as a base point for removing the peripheral portion We in the edge trimming described below. A crack C2 extends from the peripheral modified layer M2 in the thickness direction of the second wafer W2. The upper end and the lower end of the crack C2 reach, for example, the back surface W2b and the front surface W2a of the second wafer W2, respectively. The laminated wafer T with the peripheral modified layer M2 formed inside the second wafer W2 is then transported by the wafer transport device 40 to the interface laser irradiation device 80.

[0065] In the interface laser irradiation device 80, the bonding strength between the peeling promotion layer P2 and the second wafer W2 in the peripheral portion We of the second wafer W2 to be removed is reduced. Specifically, as shown in FIG. 14(b), a laser beam L(CO 2 14(c), a stress is generated inside the laser absorption layer P radially outward of the peripheral modified layer M2 formed by the internal laser irradiation device 70. Furthermore, the generated stress penetrates the peeling promotion layer P2, as shown in FIG. 14(c), and thus the stress accumulates at the boundary between the second wafer W2 and the peeling promotion layer P2.

[0066] The laminated wafer T in which the peeling modified layer M1 is formed over the entire surface of the peripheral portion We and the bonding strength between the peeling promoting layer P2 and the second wafer W2 is reduced is then transferred by the wafer transfer device 40 to the peripheral edge removing device 50.

[0067] In the edge removing apparatus 50, the edge We of the overlapped wafer T is removed (edge ​​trimmed) from the edge modified layer M2 and the crack C2 as base points, as shown in Fig. 14(d). Any edge trimming method can be selected in the edge removing apparatus 50. At this time, the bonding strength between the second wafer W2 and the peeling promoting layer P2 has been reduced by the formation of the peeling modified layer M1 when removing the edge We, so that the edge We can be easily removed.

[0068] The overlapped wafer T from which the peripheral portion We of the second wafer W2 has been removed is then transferred by the wafer transfer device 40 to the cleaning device 60. In the cleaning device 60, the overlapped wafer T is scrubbed. Thereafter, the overlapped wafer T which has been subjected to all the processes is unloaded from the cleaning device 60 by the wafer transfer device 40, and transferred to the cassette Ct on the cassette mounting table 10 by the wafer transfer device 20 via the transition device 30. In this manner, a series of wafer processes in the wafer processing system 1 is completed.

[0069] As described above, according to the technology disclosed herein, the bonding strength between the second wafer W2 and the peeling promotion layer P2 at the peripheral portion We can be reduced in the interface laser irradiation device 80, thereby enabling the peripheral portion We to be appropriately removed, i.e., edge trimmed, in the peripheral removal device 50.

[0070] The processing order of the polymerized wafer T by the internal laser irradiation device 70 and the interface laser irradiation device 80 is not limited to that of the above embodiment, and after the peripheral portion We is peeled off in the interface laser irradiation device 80, the peripheral modified layer M2 may be formed in the internal laser irradiation device 70.

[0071] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0072] D2 Device Layer L Laser light P laser absorption layer P2 peeling layer T Polymerized Wafer W1 First wafer W2 Second wafer W2a Surface W2b back

Claims

1. A substrate processing method for processing a laminated substrate in which a first substrate and a second substrate are bonded together, comprising the steps of: A peeling-promoting layer and a laser absorbing layer are formed on the second substrate in this order from the second substrate side, The substrate processing method includes: generating stress at an interface between the laser absorption layer and the peeling promotion layer by irradiating the laser absorption layer with laser light from the second substrate side; peeling the second substrate from the first substrate along a boundary between the laser absorbing layer and the peeling promotion layer.

2. 2. The substrate processing method according to claim 1, wherein the second substrate is formed by laminating, in this order from the second substrate side, the peeling promotion layer, the laser absorption layer, a device layer, and a surface film to be bonded to the first substrate.

3. The substrate processing method according to claim 2 , wherein the second substrate has a reflective film formed between the laser absorption layer and the device layer.

4. The substrate processing method according to claim 2 , wherein the first substrate has a device layer including a plurality of devices formed thereon.

5. 5. The substrate processing method according to claim 4, wherein a surface film is further formed on the device layer of the first substrate, and the device layer is bonded to the surface film of the second substrate via the surface film.

6. The substrate processing method according to claim 5 , wherein the surface films of the first substrate and the second substrate are oxide films.

7. The substrate processing method according to claim 5 , wherein the surface film of the first substrate is an adhesive.

8. A substrate processing apparatus for processing a laminated substrate in which a first substrate and a second substrate are bonded together, comprising: A peeling-promoting layer and a laser absorbing layer are formed on the second substrate in this order from the second substrate side, The substrate processing apparatus includes: a laser irradiation unit that irradiates the laser absorption layer with laser light; a peeling unit that peels the second substrate from the first substrate; A control unit that controls the operation of the laser irradiation unit and the peeling unit, The control unit is generating stress at an interface between the laser absorption layer and the peeling promotion layer by irradiating the laser absorption layer with laser light from the second substrate side; and peeling the second substrate from the first substrate along a boundary between the laser absorption layer and the peeling promotion layer.

9. A program that runs on a computer of a control device that controls a substrate processing system so as to cause the substrate processing system to execute a substrate processing method for processing a laminated substrate in which a first substrate and a second substrate are bonded together, the program comprising: A peeling-promoting layer and a laser absorbing layer are formed on the second substrate in this order from the second substrate side, The substrate processing method includes: generating stress at an interface between the laser absorption layer and the peeling promotion layer by irradiating the laser absorption layer with laser light from the second substrate side; peeling the second substrate from the first substrate along a boundary between the laser absorption layer and the peeling promotion layer.

10. A readable computer storage medium storing a program that operates on a computer of a control device that controls a substrate processing system so as to cause the substrate processing system to execute a substrate processing method for processing a laminated substrate in which a first substrate and a second substrate are bonded together, A peeling-promoting layer and a laser absorbing layer are formed on the second substrate in this order from the second substrate side, The substrate processing method includes: generating stress at an interface between the laser absorption layer and the peeling promotion layer by irradiating the laser absorption layer with laser light from the second substrate side; peeling the second substrate from the first substrate along an interface between the laser absorbing layer and the peel-facilitating layer.

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