Substrate processing equipment

Abstract

In a polymerized substrate in which a first substrate and a second substrate are joined, the second substrate is appropriately peeled off from the first substrate. [Solution] A substrate processing apparatus for processing a polymer substrate T in which a first substrate W1 and a second substrate W2, which is a silicon substrate, are bonded, comprising a program storage unit, a computer, a laser irradiation unit, and a peeling unit. On the second substrate, a peeling acceleration layer P2 and a laser absorption layer P are formed in this order from the second substrate side. The substrate processing method includes irradiating the laser absorption layer with laser light L of far-infrared wavelength from the second substrate side in the laser irradiation unit to generate stress at the interface between the laser absorption layer and the peeling acceleration layer, thereby reducing the bonding strength between the laser absorption layer and the peeling acceleration layer, and peeling the second substrate from the first substrate along the boundary between the laser absorption layer and the peeling acceleration layer in the peeling unit.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing apparatus.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a semiconductor device. Such a method for manufacturing a semiconductor device includes a heating step of locally heating a peeling oxide film by irradiating a CO2 laser from the back surface of a semiconductor substrate, and a transfer step of causing peeling to occur in the peeling oxide film and / or at the interface between the peeling oxide film and the semiconductor substrate, and transferring the semiconductor element to a transfer destination substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the polymer substrate in which the first substrate and the second substrate are joined, the technology according to the present disclosure appropriately peels the second substrate from the first substrate.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a substrate processing apparatus for processing a polymerized substrate in which a first substrate and a second substrate which is a silicon substrate are bonded together, comprising: a program storage unit for storing a program; a computer for reading the program from the program storage unit and operating the program; a laser irradiation unit; and a peeling unit, wherein the program is a program that operates on the computer to cause the substrate processing apparatus to execute a substrate processing method, the second substrate is formed by laminating a peeling accelerator layer and a laser absorption layer in that order from the second substrate side, and the substrate processing method includes: irradiating the laser absorption layer with laser light of far-infrared wavelength from the second substrate side in the laser irradiation unit to generate stress at the interface between the laser absorption layer and the peeling accelerator layer, thereby reducing the bonding strength between the laser absorption layer and the peeling accelerator layer; and peeling the second substrate from the first substrate along the boundary between the laser absorption layer and the peeling accelerator layer in the peeling unit. [Effects of the Invention]

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

[0007] [Figure 1] This is a side view showing an example of a polymerized wafer processed by a wafer processing system. [Figure 2] This is a schematic plan view illustrating the general configuration of the wafer processing system. [Figure 3] This is a side view showing a schematic configuration of a laser irradiation device for interfaces. [Figure 4] This is a plan view showing the schematic configuration of a laser irradiation device for interfaces. [Figure 5] This is an explanatory diagram showing the process of forming the peel-off modified layer according to this embodiment. [Figure 6] This is a plan view showing an example of the formation of a peel-off modified layer according to this embodiment. [Figure 7]This is an explanatory diagram showing the gas flow inside the polymerized wafer during the wafer processing according to this embodiment. [Figure 8] This is a plan view showing another example of the formation of the peel-off modified layer according to this embodiment. [Figure 9] This is an explanatory diagram showing the peeling process of the second wafer according to this embodiment. [Figure 10] This is an explanatory diagram showing the peeling process of the second wafer according to this embodiment. [Figure 11] This is an explanatory diagram showing the pressing process on the second wafer. [Figure 12] This is an explanatory diagram showing the pressing process on the second wafer. [Figure 13] This is a side view illustrating the schematic configuration of a polymerized wafer in another embodiment. [Figure 14] This is an explanatory diagram showing the flow of edge trimming according to this embodiment. [Modes for carrying out the invention]

[0008] In recent years, the manufacturing process for LEDs has involved a process known as laser lift-off, in which a laser beam is used to peel off the GaN (gallium nitride) compound crystal layer (material layer) from the sapphire substrate. The reason for this laser lift-off is that sapphire substrates are transparent to short-wavelength laser light (e.g., UV light), allowing the use of short-wavelength laser light with high absorption rates in the laser absorption layer, and offering a wide range of laser light options.

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

[0010] Generally, for example, laser light having a wavelength of FIR can be used with a CO2 laser. In the method described in Patent Document 1 mentioned above, by irradiating a peeling oxide film as a laser absorption layer with a CO2 laser, peeling is caused at the interface between the peeling oxide film and the substrate.

[0011] However, as a result of intensive studies by the present inventors, it has been found that in the laser lift-off method, peeling between the substrate and the laser absorption layer may not occur appropriately, that is, transfer may not be performed appropriately. Specifically, when there is a region where laser light is not irradiated in the plane of the laser absorption layer and the bonding strength between the laser absorption 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 (silicon piece) may be transferred together with the device layer to the surface of the laser absorption layer after the transfer process.

[0012] The technology according to the present disclosure appropriately peels the second substrate from the first substrate in a polymerized substrate in which the first substrate and the second substrate are bonded. 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 configuration are denoted by the same reference numerals, and redundant description is omitted.

[0013] As shown in FIG. 1, a polymerized wafer T as a polymerized substrate to be 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 surface on the side bonded to the second wafer W2 is referred to as a front surface W1a, and the surface on the opposite side of the front surface W1a is referred to as a back surface W1b. Similarly, in the second wafer W2, the surface on the side bonded to the first wafer W1 is referred to as a front surface W2a, and the surface on the opposite side of 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 the surface W1a of the first wafer W1. A surface film F1 is further formed on the device layer D1, and it is bonded to the second wafer W2 through the surface film F1. Examples of the surface film F1 include an oxide film (SiO2 film, TEOS film), SiC film, SiCN film, or an adhesive. Note that there may be a case 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. On the surface W2a of the second wafer W2, a peel promotion layer P2, a laser absorption layer P, a device layer D2, and a surface film F2 are laminated in this order from the surface W2a side, and it is bonded to the first wafer W1 through the surface film F2. The device layer D2 and the surface film F2 are the same as the device layer D1 and the surface film F1 of the first wafer W1, respectively. Examples of the laser absorption layer P include those that can absorb laser light (e.g., CO2 laser) as described later, such as an oxide film (SiO2 film, TEOS film). The peel promotion layer P2 is formed to facilitate the peeling (transfer) of the second wafer W2 from the first wafer W1, and is formed of a material having a lower adhesion to the second wafer W2 (silicon) than the adhesion to the laser absorption layer P, for example, silicon nitride (SiN). Note that there may be a case where the peel promotion layer P2, 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 peel promotion layer P2 and the laser absorption 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 cross-section of the peripheral edge We decreases in thickness towards its tip. In the semiconductor device manufacturing process, the back surface of the second wafer W2 formed in this way may be removed to thin it, and this thinning process may result in a sharp, pointed shape (a so-called knife edge shape) on the peripheral edge We. If this occurs, chipping may occur on the peripheral edge We of the second wafer W2, potentially damaging the wafer W2. Therefore, edge trimming, described below, may be performed to remove the peripheral edge We of the second wafer W2 before the thinning process. The peripheral edge We is the part removed in this edge trimming, and is, for example, in the radial direction from the outer edge of the second wafer W2, ranging from 0.5 mm to 3 mm.

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

[0018] As shown in Figure 2, the wafer processing system 1 has a configuration in which the loading / unloading block G1, the transport block G2, and the processing block G3 are connected as a single unit. The loading / unloading block G1, the transport block G2, and the processing block G3 are arranged in this order from the negative X-axis direction.

[0019] The loading / unloading block G1 is used to load and unload cassettes Ct, Cw1, and Cw2, each capable of accommodating multiple polymerized wafers T, multiple first wafers W1, and multiple second wafers W2, respectively, to and from the outside. The loading / unloading block G1 is provided with a cassette mounting table 10. In the illustrated example, multiple cassettes, for example, three cassettes Ct, Cw1, and Cw2, can be freely mounted on the cassette mounting table 10 in a line along the Y-axis. 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] On the transport block G2, a wafer transport device 20 is provided adjacent to the cassette mounting table 10 on the positive X-axis side of the cassette mounting table 10. The wafer transport device 20 is configured to move freely on a transport path 21 extending in the Y-axis direction. The wafer transport device 20 also has, for example, two transport arms 22, 22 that hold and transport the superimposed wafer T, the first wafer W1, and the second wafer W2. Each transport arm 22 is configured to move freely in the horizontal direction, vertical direction, around the horizontal axis, and around the vertical axis. Note that the configuration of the transport arms 22 is not limited to this embodiment and can be any configuration. The wafer transport device 20 is configured to transport the superimposed wafer T, the first wafer W1, and the second wafer W2 to the cassettes Ct, Cw1, Cw2 of the cassette mounting table 10, and to the transition device 30 described later.

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

[0022] Processing block G3 includes a wafer transport device 40, a peripheral edge removal 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 move along a transport path 41 extending in the X-axis direction. The wafer transport device 40 also 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 move horizontally, vertically, around the horizontal axis, and around the vertical axis. Note that the configuration of the transport arms 42 is not limited to this embodiment and can be any configuration. 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.

[0024] The peripheral removal device 50 is provided on the positive Y-axis side of the wafer transport device 40 and removes the peripheral portion We of the second wafer W2, i.e., performs edge trimming. The cleaning device 60 is provided on the negative Y-axis side of the wafer transport device 40 and cleans the polymerized wafer T after peeling or after the removal of the peripheral portion We. The internal laser irradiation device 70, which serves as a second laser irradiation unit, is provided on the positive Y-axis side of the wafer transport device 40 and irradiates the inside of the second wafer W2 with laser light (internal laser light, e.g., a YAG laser) to form the peripheral modification layer M2, which will be described later and will serve as a starting point for peeling off the peripheral portion We. The interface laser irradiation device 80 is provided on the negative Y-axis 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., a CO2 laser). The configuration of the interface laser irradiation device 80 will be described later.

[0025] The wafer processing system 1 described above 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 that controls the processing of the polymerized wafer T in the wafer processing system 1. The program storage unit also stores a program that controls the operation of the drive systems such as the various processing devices and transport devices described above to realize the wafer processing in the wafer processing system 1 described later. Note that the above program may have been recorded on a storage medium H that is readable by a computer and installed from the storage medium H to the control device 90.

[0026] 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, that is, the transfer processing of the device layer D2 onto the first wafer W1, and the edge trimming processing of the second wafer W2 can be performed. For example, if the edge trimming processing 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] Furthermore, in this embodiment, as will be described later, the separation of the second wafer W2 from the first wafer W1 is performed in the interface laser irradiation device 80, but the wafer processing system 1 may also be further provided with a separate separation device as a separation unit.

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

[0029] As shown in Figures 3 and 4, the interface laser irradiation device 80 has a chuck 100 that holds the polymerized wafer T on its upper surface. The chuck 100 holds a part or the entire surface W1b of the first wafer W1 by suction. The chuck 100 is provided with a lifting pin (not shown) for transferring the polymerized wafer T to and from the transport arm 42. The lifting pin is configured to move up and down by being inserted through a through hole (not shown) formed through the chuck 100, and supports the polymerized wafer T from below to move it up and down.

[0030] The chuck 100 is supported by the slider table 102 via an air bearing 101. A rotating mechanism 103 is provided on the underside of the slider table 102. The rotating mechanism 103 incorporates, for example, a motor as a drive source. The chuck 100 is configured to rotate freely around the θ axis (vertical axis) via the air bearing 101 through the rotating 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 the base 106, by a moving mechanism 104 provided on its underside. The drive source for the moving mechanism 104 is not particularly limited, but for example, a linear motor can be used.

[0031] A laser head 110, which serves 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 the polymerized wafer T held by the chuck 100 with laser light. In this embodiment, the laser light is pulsed CO2 laser light, and the laser light emitted from the laser head 110 passes through the second wafer W2 and irradiates the laser absorption layer P. The wavelength of the CO2 laser light is, for example, 8.9 μm to 11 μm. The laser head 110 is configured to be able to move up and down by a lifting mechanism (not shown). The laser light source is provided at a separate location outside the laser head 110.

[0032] Furthermore, above the chuck 100, a transport pad 120 is provided as a peeling unit, having a suction surface on its lower surface for adsorbing and holding the back surface W2b of the second wafer W2. The transport pad 120 is configured to be able to move up and down by a lifting mechanism (not shown). The transport pad 120 transports the second wafer W2 between the chuck 100 and the transport arm 42. Specifically, after moving the chuck 100 to below the transport pad 120 (the handover position with the transport arm 42), the transport pad 120 is lowered to adsorb and hold the back surface W2b of the second wafer W2, and then the transport pad 120 is raised again to peel it from the first wafer W1. The peeled second wafer W2 is transferred from the transport pad 120 to the transport arm 42 and discharged from the interface laser irradiation device 80. The transport pad 120 may also be configured to reverse the front and back surfaces of the wafer by a reversal mechanism (not shown).

[0033] Next, a wafer processing procedure performed using the wafer processing system 1 configured as described above will be explained. In the following explanation, a laser lift-off procedure will be described in which the wafer processing system 1 performs a laser lift-off procedure, that is, when the device layer D2 of the second wafer W2 is transferred to the first wafer W1. In this embodiment, the first wafer W1 and the second wafer W2 are bonded together in an external bonding apparatus (not shown) to the wafer processing system 1 to form a polymerized wafer T in advance.

[0034] First, a cassette Ct containing multiple polymerized wafers T is placed on the cassette mounting table 10 of the loading / unloading block G1. Next, the polymerized wafers T in the cassette Ct are removed by the wafer transport device 20. The polymerized wafers T removed from the cassette Ct are then 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 separated from the first wafer W1 (laser lift-off process).

[0035] Specifically, the polymerized wafer T, which is held by suction on the chuck 100 via a lifting pin from the transport arm 42, is first moved to a processing position by the moving mechanism 104. This processing position is a position from which laser light can be irradiated onto the polymerized wafer T (laser absorption layer P) from the laser head 110.

[0036] Next, as shown in Figures 5 and 6, laser light L (CO2 laser light) is pulsed from the laser head 110 toward the back surface W2b of the second wafer W2. At this time, the laser light L passes through the second wafer W2 and the delamination promoting layer P2 from the back surface W2b side of the second wafer W2 and is absorbed by the laser absorption layer P. Then, as shown in Figure 7(a), stress is generated inside the laser absorption layer P that has absorbed the laser light L. Hereafter, the stress accumulation layer formed by the irradiation of the laser light in this way, which serves as the starting point for delamination of the second wafer W2 (the starting point for transfer of the device layer D2), is sometimes referred to as the "delamination modification layer M1". Note that almost all of the energy of the laser light L irradiated onto the laser absorption layer P is absorbed by the formation of the delamination modification layer M1 and does not reach the device layer D2. Therefore, damage to the device layer D2 can be suppressed.

[0037] Here, the laser beam L irradiated onto the laser absorption layer P is controlled to an output level that does not cause the peeling acceleration layer P2 and the laser absorption layer P to separate due to the stress generated by the irradiation of the laser beam L.

[0038] In this way, irradiation with laser light L does not cause delamination between the delamination-promoting layer P2 and the laser absorption layer P, and by eliminating the escape route for the generated stress, stress accumulates inside the laser absorption layer P, thereby forming the delamination-modifying layer M1. More specifically, for example, irradiation with laser light gasifies the laser absorption layer P, and by eliminating the escape route for the generated gas as described above, compressive stress is accumulated as the delamination-modifying layer M1. Alternatively, for example, heat is generated in the laser absorption layer P due to the absorption of laser light, and due to the difference in thermal expansion coefficients between the delamination-promoting layer P2 and the laser absorption layer P, shear stress is accumulated as the delamination-modifying layer M1.

[0039] The stress generated by irradiation with laser light L normally remains at the irradiation site of the laser light L (inside the laser absorption layer P), as described above, and forms the delamination modification layer M1. However, in this embodiment, a delamination accelerating layer P2 is formed between the surface W2a of the second wafer W2 and the laser absorption layer P, and the adhesion between the delamination accelerating layer P2 and the second wafer W2 is less than the adhesion between the delamination accelerating layer P2 and the laser absorption layer P. Therefore, as shown in Figure 7(b), the stress generated inside the laser absorption layer P passes through the delamination accelerating layer P2 and accumulates at the interface between the delamination accelerating layer P2 and the second wafer W2. In other words, the stress generated by irradiation with laser light L moves to the interface between the delamination accelerating layer P2 and the second wafer W2, where it can reside more stably, and accumulates there. When stress accumulates at the interface between the delamination accelerating layer P2 and the second wafer W2 in this way, the bonding strength between the delamination accelerating layer P2 and the second wafer W2 decreases.

[0040] In this embodiment, the irradiation of the laser absorption layer P with laser light L, i.e., the delamination of the delamination accelerating layer P2 and the second wafer W2, is performed across the entire surface of the laser absorption layer P in a plan view. Specifically, when irradiating the laser absorption layer P with laser light L, the chuck 100 (polymerized 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. As a result, the laser light L is irradiated onto the laser absorption layer P, for example, from the radial outside to the inside, and consequently, the entire surface of the laser absorption layer P is irradiated in a spiral pattern from the outside to the inside. The black arrows shown in Figure 6 indicate the rotation direction of the chuck 100. The formation direction of the delamination modification layer M1 may be from the radial inside to the outside.

[0041] Here, the spacing between adjacent delamination-modified layers M1, in other words, the pulse interval (frequency) of the laser light L, is controlled to an interval that prevents delamination from occurring in adjacent delamination-modified layers M1 due to the impact generated during the formation of the delamination-modified layer M1. Specifically, for example, it is preferable that adjacent delamination-modified layers M1 are formed so that they do not overlap each other in a plan view. Furthermore, it is preferable that adjacent delamination-modified layers M1 are formed in close proximity to each other.

[0042] As shown in Figure 8, the laser beam L may be irradiated in a concentric, ring-like pattern in the laser absorption layer P. However, in this case, since the rotation of the chuck 100 and the Y-direction of the chuck 100 alternate, irradiating the laser beam L in a spiral pattern as described above allows for a shorter irradiation time and improved throughput.

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

[0044] When the laser beam L is irradiated onto the in-plane front surface of the laser absorption layer P, the chuck 100 is then moved by the moving mechanism 104 to a transfer position below the transport pad 120. At the transfer position, as shown in Figure 9(a), the transport pad 120 adsorbs and holds the back surface W2b of the second wafer W2, and then, as shown in Figure 9(b), the transport pad 120 is raised to peel the second wafer W2 from the peel-promoting 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 beam accumulates at the interface between the peel-promoting layer P2 and the second wafer W2, reducing the bonding strength, so the second wafer W2 can be peeled from the peel-promoting layer P2 without applying a large load.

[0045] Furthermore, as described above, the delamination modification layers M1 are formed so as not to overlap with each other. However, the stress accumulated by the formation of the delamination modification layers M1 is released to the outside when delamination occurs between the second wafer W2 and the delamination accelerating layer P2 at the formation location of the delamination modification layer M1. In this embodiment, as described above, the delamination modification layers M1 are formed in close proximity to each other. Therefore, when delamination occurs at the formation location of adjacent delamination modification layers M1, that is, when stress is released to the outside at the adjacent location, the stress is released in a chain reaction. In other words, when a part of the interface between the delamination accelerating layer P2 and the second wafer W2 is delaminated by raising the transport pad 120, the entire surface of the second wafer W2 is delaminated in a chain reaction starting from that delamination point. In other words, the second wafer W2 can be delaminated from the delamination accelerating layer P2 more appropriately without applying a large load.

[0046] However, as shown in Figure 1, in the laser absorption layer P irradiated with laser light L, there may be areas (unpeeled areas R1) where the laser light L does not reach the layer P2 and the second wafer W2, due to factors such as the frequency of the laser light L and the rotation speed of the chuck 100, and thus delamination from the delamination accelerating layer P2 to the second wafer W2 does not occur. However, according to this embodiment, since the delamination accelerating layer P2 is formed of a material with low adhesion to the second wafer W2 (silicon), even if the unpeeled areas R1 are formed, the delamination accelerating layer P2 and the second wafer W2 can be easily separated. Furthermore, because the delamination accelerating layer P2 and the second wafer W2 are properly separated in this way, it is possible to appropriately suppress the transfer of a part of the second wafer W2 (silicon fragment) to the surface of the delamination accelerating layer P2 after the second wafer W2 has been peeled off. In addition, this makes it possible to suppress damage to the second wafer W2 after delamination.

[0047] Furthermore, in order to properly perform delamination at the interface between the delamination accelerating layer P2 and the second wafer W2, the stress generated by the irradiation of laser light needs to pass through the delamination accelerating layer P2. Specifically, for example, if the laser absorption layer P is gasified, the generated gas needs to pass through the laser absorption layer P. Also, for example, when delamination between the delamination accelerating layer P2 and the second wafer W2 is performed due to the difference in thermal expansion coefficients, the heat generated by the irradiation of laser light needs to be properly transferred to the interface between the delamination accelerating layer P2 and the second wafer W2. However, if the film thickness of the delamination accelerating layer P2 is large, the generated stress may not properly pass through the delamination accelerating layer P2 and may remain at the interface between the delamination accelerating layer P2 and the laser absorption layer P. Therefore, in order to properly perform delamination at the interface between the delamination accelerating layer P2 and the second wafer W2, the film thickness of the delamination accelerating layer P2 is preferably thin compared to the laser absorption layer P, specifically, for example, about one-tenth the film thickness of the laser absorption layer P. By reducing the thickness of the peel-accelerating layer P2 in this way, the generated stress can be appropriately transmitted through the peel-accelerating layer P2, and the bonding strength of the second wafer W2 to the peel-accelerating layer P2 can be reduced. In other words, the second wafer W2 can be appropriately peeled from the peel-accelerating layer P2.

[0048] However, even if the film thickness of the peel-accelerating layer P2 increases and the generated stress does not properly penetrate the peel-accelerating layer P2 but remains at the interface between the peel-accelerating layer P2 and the laser absorption layer P, the peel-accelerating layer P2 can still act as a protective film for the second wafer W2. In other words, by peeling the second wafer W2 from the inside, the transfer of silicon fragments along with the device layer D2 to the interface after peeling can be appropriately suppressed.

[0049] Specifically, a delamination modification layer M1 is formed due to stress generated at the interface between the delamination accelerating layer P2 and the laser absorption layer P. If stress remains at this interface, the second wafer W2 is delaminated from the first wafer W1 at the boundary between the delamination accelerating layer P2 and the laser absorption layer P, as shown in Figure 10. At this time, since the second wafer W2 is delaminated from the laser absorption layer P via the delamination accelerating layer P2, the second wafer W2 does not remain at the delamination interface. In other words, this protects the surface W2a of the second wafer W2 and suppresses damage to the delamination surface.

[0050] The second wafer W2, detached from the first wafer W1, is transferred from the transport pad 120 to the transport arm 42 of the wafer transport device 40 and then transported to the cassette Cw2 on the cassette mounting table 10. The surface W2a of the second wafer W2, after being discharged from the interface laser irradiation device 80, may be cleaned in the cleaning device 60 before being transported to the cassette Cw2.

[0051] Meanwhile, the first wafer W1 held in the chuck 100 is transferred to the transport arm 42 of the wafer transport device 40 via the lifting pin and transported to the cleaning device 60. In the cleaning device 60, the surface of the peeling acceleration layer P2, which is the peeling surface, is scrubbed clean. In addition, the back surface W1b of the first wafer W1 may also be cleaned in the cleaning device 60 along with the surface of the peeling acceleration layer P2.

[0052] Subsequently, the first wafer W1, having undergone all the processing necessary for transferring the device layer D2 to the first wafer W1, is transported via the transition device 30 to the cassette Cw1 of the cassette stand 10 by the wafer transport device 20. In this way, the series of wafer processing steps in the wafer processing system 1 are completed.

[0053] According to the above embodiment, since a peel-accelerating layer P2 is formed between the second wafer W2 and the laser absorption layer P, the second wafer W2 can be properly peeled from the first wafer W1, that is, the device layer D2 can be properly transferred. Specifically, the stress generated in the laser absorption layer P by irradiation with laser light moves to the boundary between the second wafer W2 and the peel-accelerating layer P2, thereby reducing the bonding strength at the boundary between the second wafer W2 and the peel-accelerating layer P2, so that the second wafer W2 and the peel-accelerating layer P2 can be properly peeled off. Furthermore, since the peel-accelerating layer P2 is formed of a material with low adhesion to the second wafer W2 (for example, SiN), the peel-accelerating layer P2 can be peeled off the second wafer W2 even more appropriately.

[0054] In the above embodiment, a material with low adhesion to the second wafer W2 (silicon) was used as the peel-accelerating layer P2. However, the material used for the peel-accelerating 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 due to heat generated by irradiation of the laser light L with the laser absorption layer P will differ between the second wafer W2 and the peel-accelerating layer P2. This will generate a shear force at the interface between the second wafer W2 and the peel-accelerating layer P2, allowing the second wafer W2 and the peel-accelerating layer P2 to be separated. In particular, when shear stress is generated and accumulated as a peel-modifying layer M1 at the interface between the second wafer W2 and the peel-accelerating layer P2 as described above, using a material with a different coefficient of thermal expansion as the peel-accelerating layer P2 allows for more appropriate separation of the second wafer W2 and the peel-accelerating layer P2.

[0055] In the above embodiment, the second wafer W2 was peeled off from the peeling acceleration layer P2 by irradiation with laser light L. However, when peeling off the second wafer W2, warping may occur in the polymerized wafer T. If warping occurs in the polymerized wafer T in this way, it may become impossible to properly perform wafer processing in the wafer processing system 1. Therefore, in order to suppress this warping of the polymerized wafer T, the polymerized wafer T may be pressed from above when the laser light L is irradiated onto the laser absorption layer P.

[0056] For example, if the polymerized wafer T warps to an upward convex shape, the center of the polymerized wafer T may be pressed with the pressing member 200, as shown in Figure 11. Specifically, when peeling off the second wafer W2, first, a peel-modified layer M1 is formed in advance in the center of the laser absorption layer P, which is the pressing area of ​​the pressing member 200. The direction of formation of the peel-modified layer M1 with respect to the radial direction is not particularly limited. After forming the peel-modified layer M1 in the center of the laser absorption layer P, the center of the polymerized wafer T on which the peel-modified layer M1 is formed is then pressed with the pressing member 200. Then, with the center pressed by the pressing member 200, the peel-modified layer M1 is formed on the outer periphery of the laser absorption layer P, and then the second wafer W2 is peeled off. At this time, since the central part of the polymerized wafer T is held down by the pressing member 200, the formation of the peel-modified layer M1 on the outer periphery of the laser absorption layer P and the occurrence of warping in the polymerized wafer T during the peeling of the second wafer W2 are suppressed.

[0057] Furthermore, since the polymerized wafer T is rotated when the laser beam L is irradiated, it is desirable that the end of the pressing member 200 be configured to rotate together with the polymerized wafer T.

[0058] For example, if the polymerized wafer T warps and deforms into a downward convex shape, the peripheral edge We of the polymerized wafer T may be pressed by the pressing member 200, as shown in Figure 12. Specifically, when peeling off the second wafer W2, first, a peel-modified layer M1 is formed in advance on the outer periphery of the laser absorption layer P, which is the pressing area of ​​the pressing member 200. After forming the peel-modified layer M1 on the outer periphery of the laser absorption layer P, the outer periphery of the polymerized wafer T on which the peel-modified layer M1 is formed is then pressed by the pressing member 200. Then, with the outer periphery pressed by the pressing member 200, the peel-modified layer M1 is formed on the center of the laser absorption layer P, and then the second wafer W2 is peeled off. At this time, since the outer periphery of the polymerized wafer T is held down by the pressing member 200, the formation of the peel-modified layer M1 on the center of the laser absorption layer P and the occurrence of warping in the polymerized wafer T during the peeling of the second wafer W2 are suppressed.

[0059] In addition, in the polymerized wafer T processed according to the above embodiment, a reflective film R may be provided between the laser absorption layer P and the device layer D2, as shown in Figure 13. That is, the reflective film R is formed on the side of the laser absorption layer P opposite to the incident surface of the laser light L. A material with high reflectivity to the laser light L and a high melting point, such as a metal film, is used for the reflective film R. Note that the device layer D2 is a functional layer 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 by the laser absorption layer P. However, any remaining laser light L that is not absorbed 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] Furthermore, 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 embodiments described above, the case in which the wafer processing system 1 performs laser lift-off processing of the polymerized wafer T, that is, transfer processing of the device layer D2 onto the first wafer W1, was explained. However, as mentioned above, the wafer processing system 1 can also perform edge trimming processing on the second wafer W2. The case in which the wafer processing system 1 performs edge trimming on the second wafer W2 will be described below.

[0063] First, the polymerized wafer T is removed from the cassette Ct placed on the cassette mounting table 10 of the loading / unloading block G1 by the wafer transport device 20, 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 Figure 14(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 will serve as a starting point for removing the peripheral portion We in the edge trimming described later. Cracks C2 extend from the peripheral modification layer M2 in the thickness direction of the second wafer W2. The upper and lower ends of the cracks C2 reach, for example, the back surface W2b and the front surface W2a of the second wafer W2, respectively. The polymerized wafer T, in which the peripheral modification layer M2 has been formed inside the second wafer W2, is then transported to the interface laser irradiation device 80 by the wafer transport device 40.

[0065] In the interface laser irradiation device 80, the bonding strength between the polymerized wafer T and the peel-promoting layer P2 at the peripheral We, which is the target of removal from the second wafer W2, is reduced. Specifically, as shown in Figure 14(b), the laser absorption layer P is irradiated with laser light L (CO2 laser), and stress is generated inside the laser absorption layer P radially outside the peripheral modification layer M2 formed by the internal laser irradiation device 70. Furthermore, as shown in Figure 14(c), the generated stress passes through the peel-promoting layer P2, causing stress to accumulate at the boundary between the second wafer W2 and the peel-promoting layer P2.

[0066] A delamination-modified layer M1 is formed over the entire peripheral edge We, and the polymerized wafer T, with reduced bonding strength between the delamination-promoting layer P2 and the second wafer W2, is then transported to the peripheral edge removal device 50 by the wafer transport device 40.

[0067] In the peripheral removal apparatus 50, as shown in Figure 14(d), the peripheral portion We of the second wafer W2 is removed (edge ​​trimmed) from the polymerized wafer T, starting from the peripheral modification layer M2 and the crack C2. The edge trimming method in the peripheral removal apparatus 50 can be arbitrarily selected. At this time, when removing the peripheral portion We, the bonding strength between the second wafer W2 and the peeling acceleration layer P2 is reduced due to the formation of the peeling modification layer M1, so the removal of the peripheral portion We can be easily performed.

[0068] The polymerized wafer T, from which the peripheral edge 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, the polymerized wafer T is scrubbed clean. After all processing is completed, the polymerized wafer T is removed from the cleaning device 60 by the wafer transport device 40 and transported to the cassette Ct of the cassette stand 10 by the wafer transport device 20 via the transition device 30. Thus, the series of wafer processing in the wafer processing system 1 is completed.

[0069] As described above, the technology according to this disclosure makes it possible to reduce the bonding strength between the second wafer W2 and the peeling acceleration layer P2 at the peripheral We in the interface laser irradiation apparatus 80, thereby enabling the peripheral removal apparatus 50 to properly remove the peripheral We, i.e., perform edge trimming.

[0070] 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. After the peripheral 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 in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways 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 peel-promoting layer T Polymerized wafer W1 First wafer W2, second wafer W2a surface W2b Reverse side

Claims

1. A substrate processing apparatus for processing a polymerized substrate in which a first substrate and a second substrate which is a silicon substrate are joined together, A program storage unit for storing programs, A computer that reads the program from the program storage unit and operates the program, Laser irradiation section, Having a peeling portion, The program is a program that runs on the computer to cause the substrate processing apparatus to execute a substrate processing method, On the second substrate, a peel-promoting layer and a laser absorption layer are formed in this order from the second substrate side. The substrate processing method is In the laser irradiation section, by irradiating the laser absorption layer with laser light of far-infrared wavelength from the second substrate side, stress is generated at the interface between the laser absorption layer and the peel-promoting layer, thereby reducing the bonding strength between the laser absorption layer and the peel-promoting layer. This includes peeling the second substrate from the first substrate along the boundary between the laser absorption layer and the peeling acceleration layer in the peeling portion, Circuit board processing equipment.

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

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

4. The substrate processing apparatus according to claim 2, wherein a device layer including a plurality of devices is formed on the first substrate.

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

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

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

8. Reducing the bonding strength between the laser absorption layer and the peel-promoting layer is, By irradiating the laser light in a pulsed manner, The substrate processing apparatus according to claim 1, further comprising forming a delamination modification layer that leaves the stress at the interface between the laser absorption layer and the delamination promoting layer.

9. The substrate processing apparatus according to claim 1, wherein the thickness of the peel-promoting layer is such that the stress accumulated at the interface between the laser absorption layer and the peel-promoting layer remains when the laser light is irradiated.

10. The substrate processing apparatus according to claim 1, wherein the laser absorption layer is made of TEOS.

Images