Substrate processing method, substrate processing apparatus, and substrate processing system

Abstract

The invention provides a substrate processing method, a substrate processing apparatus, and a substrate processing system. A method for transferring a device layer formed on the surface of a second substrate to a first substrate in a superimposed substrate in which the first substrate and the second substrate are bonded together, laser light is irradiated in a pulsed manner from the rear surface side of the second substrate to a laser light absorbing layer formed between the second substrate and the device layer.

Description

[0001] This application is a divisional application of the invention patent application with application number 202080087508.3, application date December 9, 2020, and invention name “Substrate processing method and substrate processing device”. Technical Field

[0002] The present disclosure relates to a substrate processing method and a substrate processing apparatus. Background Art

[0003] Patent Document 1 discloses a method for manufacturing a semiconductor device. This method includes a heating step in which a CO2 laser is irradiated from the backside of a semiconductor substrate to locally heat a lift-off oxide film; and a transfer step in which a semiconductor element is transferred to a transfer target substrate by causing lift-off in the lift-off oxide film and / or at the boundary between the lift-off oxide film and the semiconductor substrate.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-220749 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The technology according to the present disclosure appropriately transfers a device layer formed on the surface of a second substrate to the first substrate in a superposed substrate formed by bonding a first substrate and a second substrate.

[0009] Solutions for solving problems

[0010] One embodiment of the present disclosure is a method for transferring a device layer formed on the surface of a second substrate to a first substrate in a superimposed substrate formed by bonding the first substrate and the second substrate. In the method, a laser absorption layer formed between the second substrate and the device layer is irradiated with a pulsed laser from the back side of the second substrate.

[0011] Effects of the Invention

[0012] According to the present disclosure, in a superposed substrate formed by bonding a first substrate and a second substrate, a device layer formed on the surface of the second substrate can be appropriately transferred to the first substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is an explanatory diagram comparing the laser power when a pulse wave and a continuous wave are used.

[0014] Figure 2This is a side view schematically showing the structure of a stacked wafer processed in a wafer processing system.

[0015] Figure 3 It is a plan view schematically showing the outline of the structure of the wafer processing system.

[0016] Figure 4 It is a side view schematically showing the structure of the laser irradiation device according to this embodiment.

[0017] Figure 5 It is a plan view schematically showing the structure of the laser irradiation device according to this embodiment.

[0018] Figure 6 This is an explanatory diagram showing how the laser absorption layer is irradiated with laser light in this embodiment.

[0019] Figure 7 This is an explanatory diagram showing how the laser absorption layer is irradiated with laser light in this embodiment.

[0020] Figure 8 This is an explanatory diagram showing a state in which the laser absorption layer is irradiated with laser light in a modification of the present embodiment.

[0021] Figure 9 It is an explanatory diagram showing a state in which the second wafer is peeled off from the laser absorption layer.

[0022] Figure 10 It is an explanatory diagram schematically showing the outline of the structure of a laser irradiation unit according to another embodiment.

[0023] Figure 11 This is an explanatory diagram showing how the frequency of laser light is changed by an acousto-optic modulator in another embodiment.

[0024] Figure 12 This is an explanatory diagram showing how the frequency of laser light is changed by an acousto-optic modulator in another embodiment.

[0025] Figure 13 It is an explanatory diagram schematically showing the outline of the structure of a laser irradiation unit according to another embodiment.

[0026] Figure 14 It is an explanatory diagram schematically showing the outline of the structure of a laser irradiation unit according to another embodiment.

[0027] Figure 15 It is a side view schematically showing the structure of a laser irradiation device according to another embodiment.

[0028] Figure 16 It is a plan view schematically showing the structure of a laser irradiation device according to another embodiment.

[0029] Figure 17 This is an explanatory diagram showing how the laser absorption layer is irradiated with laser light in another embodiment.

[0030] Figure 18 This is an explanatory diagram showing how the laser absorption layer is irradiated with laser light in another embodiment.

[0031] Figure 19 This is an explanatory diagram showing how the laser absorption layer is irradiated with laser light in another embodiment.

[0032] Figure 20 It is a side view schematically showing the structure of a laser irradiation device according to another embodiment.

[0033] Figure 21 It is a side view schematically showing the structure of the guide portion.

[0034] Figure 22 It is a side view schematically showing the structure of the holding member.

[0035] Figure 23 It is a plan view schematically showing the structure of the guide portion and the holding member.

[0036] Figure 24 This is an explanatory diagram showing a state in which a device layer formed on the surface of a second wafer is transferred to a first wafer in another embodiment.

[0037] Figure 25 This is an explanatory diagram showing a state in which a device layer formed on the surface of a second wafer is transferred to a first wafer in another embodiment.

[0038] Figure 26 This is an explanatory diagram showing a state in which a device layer formed on the surface of a second wafer is transferred to a first wafer in another embodiment.

[0039] Figure 27 This is an explanatory diagram showing a state in which a device layer formed on the surface of a second wafer is transferred to a first wafer in another embodiment.

[0040] Figure 28 This is an explanatory diagram showing a state in which a device layer formed on the surface of a second wafer is transferred to a first wafer in another embodiment.

[0041] Figure 29 This is a side view schematically showing the structure of stacked wafers in another embodiment. DETAILED DESCRIPTION

[0042] In recent years, laser lift-off (LAL) has been used in LED manufacturing processes to remove GaN (gallium nitride) compound crystal layers (material layers) from sapphire substrates using lasers. Laser lift-off is performed because sapphire substrates are transparent to short-wavelength lasers (such as UV light), allowing the use of short-wavelength lasers with high absorption rates in the absorption layer, thus widening the range of laser options available.

[0043] On the other hand, in the semiconductor device manufacturing process, a device layer formed on the surface of one substrate (a semiconductor, such as a silicon substrate) is transferred to another substrate. Silicon substrates are generally transparent to lasers in the NIR (near-infrared) region, but the absorption layer is also transparent to NIR lasers, posing a risk of damage to the device layer. Therefore, lasers in the FIR (far-infrared) region are used for laser lift-off in semiconductor device manufacturing.

[0044] Generally, a laser having a wavelength of FIR can be used, for example, a CO 2 laser. In the method described in Patent Document 1, the exfoliation oxide film is irradiated with a CO 2 laser to cause exfoliation at the boundary between the exfoliation oxide film and the substrate.

[0045] Here, the inventors of the present invention have conducted in-depth research and found that sometimes peeling does not occur simply by irradiating with CO2 laser. In other words, it was found that the main cause of peeling is not the energy of CO2 laser, but the peak power (maximum intensity of laser). For example, Figure 1 As shown, when the CO2 laser is continuously oscillated (using a continuous wave), it is difficult to increase the peak power, and sometimes it is impossible to produce ablation. On the other hand, when the CO2 laser is pulsed (using a pulsed wave), the peak power can be increased, and ablation can be produced. In the present disclosure, the laser light obtained by oscillating the CO2 laser in a pulsed manner is a so-called pulsed laser, and its power repeatedly changes between 0 (zero) and a maximum value.

[0046] In addition, when the CO2 laser is continuously oscillated, the thermal influence is large, so stable laser lift-off cannot be performed, and the device layer may also be damaged by heat. Therefore, from this point of view, the CO2 laser can also be irradiated in a pulsed state.

[0047] As described above, to separate the substrate from the peeling oxide film (device layer), it is necessary to irradiate the peeling oxide film with pulsed CO2 laser light. However, the method in Patent Document 1 does not consider or suggest the use of pulsed laser light. Therefore, conventional device layer transfer methods have room for improvement.

[0048] The technology disclosed herein appropriately transfers a device layer formed on the surface of a second substrate to a first substrate in a superimposed substrate formed by bonding a first substrate to a second substrate. Below, a wafer processing system including a laser irradiation device as a substrate processing device and a wafer processing method as a substrate processing method according to this embodiment are described with reference to the accompanying drawings. Furthermore, in this specification and the accompanying drawings, elements having substantially the same functional structure are denoted by the same reference numerals to omit repeated descriptions.

[0049] In the wafer processing system 1 described later in this embodiment, as Figure 2 As shown, a superposed wafer T, which is a superposed substrate formed by bonding a first wafer W1 serving as a first substrate to a second wafer W2 serving as a second substrate, is processed. Hereinafter, the surface of the first wafer W1 that is bonded to the second wafer W2 is referred to as the front surface W1a, and the surface opposite to the front surface W1a is referred to as the back surface W1b. Similarly, the surface of the second wafer W2 that is bonded to the first wafer W1 is referred to as the front surface W2a, and the surface opposite to the front surface W2a is referred to as the back surface W2b.

[0050] The first wafer W1 is, for example, a semiconductor wafer such as a silicon substrate. On the surface W1a of the first wafer W1, a device layer D1 and a surface film F1 are stacked in the order described, starting from the surface W1a side. The device layer D1 includes a plurality of devices. Examples of the surface film F1 include an oxide film (SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive. Furthermore, there may be cases where the device layer D1 and the surface film F1 are not formed on the surface W1a.

[0051] The second wafer W2 is also a semiconductor wafer such as a silicon substrate. On the surface W2a of the second wafer W2, a laser absorption layer P, a device layer D2, and a surface film F2 are overlapped in the order described starting from the surface W2a side. The laser absorption layer P absorbs the laser light irradiated from the laser irradiation unit 110 as described later. The laser absorption layer P can be made of, for example, an oxide film (SiO2 film), but there is no particular limitation as long as it absorbs the laser light. The device layer D2 and the surface film F2 are respectively the same as the device layer D1 and the surface film F1 of the first wafer W1. Moreover, the surface film F1 of the first wafer W1 is bonded to the surface film F2 of the second wafer W2. In addition, the position of the laser absorption layer P is not limited to the above-mentioned embodiment. For example, it can also be formed between the device layer D2 and the surface film F2. In addition, there is also a case where the device layer D2 and the surface film F2 are not formed on the surface W2a. In this case, the laser absorption layer P is formed on the first wafer W1 side, and the device layer D1 on the first wafer W1 side is transferred to the second wafer W2 side.

[0052] like Figure 3As shown, the wafer processing system 1 has a structure that integrally connects a loading / unloading block 10, a transport block 20, and a processing block 30. The loading / unloading block 10 and the processing block 30 are arranged around the transport block 20. Specifically, the loading / unloading block 10 is located on the negative Y-axis side of the transport block 20. The laser irradiation device 31 (described later) of the processing block 30 is located on the negative X-axis side of the transport block 20, and the cleaning device 32 (described later) is located on the positive X-axis side of the transport block 20.

[0053] The loading / unloading block 10 is used, for example, to load and unload cassettes Ct, Cw1, and Cw2 to and from the outside. The cassettes Ct, Cw1, and Cw2 can accommodate multiple overlapping wafers T, multiple first wafers W1, and multiple second wafers W2, respectively. A cassette mounting table 11 is provided in the loading / unloading block 10. In the illustrated example, multiple, for example, three, cassettes Ct, Cw1, and Cw2 can be freely mounted in a row along the X-axis on the cassette mounting table 11. The number of cassettes Ct, Cw1, and Cw2 mounted on the cassette mounting table 11 is not limited to this embodiment and can be arbitrarily determined.

[0054] A wafer conveying device 22 is provided on the conveying block 20, and the wafer conveying device 22 is configured to be movable on a conveying path 21 extending in the X-axis direction. The wafer conveying device 22 has, for example, two conveying arms 23, 23 for holding and conveying the overlapping wafer T, the first wafer W1, and the second wafer W2. Each conveying arm 23 is configured to be movable in the horizontal direction and the vertical direction and to be movable around the horizontal axis and the vertical axis. In addition, the structure of the conveying arm 23 is not limited to this embodiment, and any structure can be adopted. Moreover, the wafer conveying device 22 is configured to be able to convey the overlapping wafer T, the first wafer W1, and the second wafer W2 to the boxes Ct, Cw1, and Cw2 of the box mounting table 11, the laser irradiation device 31 described later, and the cleaning device 32.

[0055] The processing block 30 includes a laser irradiation device 31 and a cleaning device 32. The laser irradiation device 31 irradiates the laser absorption layer P of the second wafer W2 with laser light. The structure of the laser irradiation device 31 will be described later.

[0056] The cleaning device 32 cleans the surface of the laser absorption layer P formed on the surface W1a of the first wafer W1 separated by the laser irradiation device 31. For example, a brush is brought into contact with the surface of the laser absorption layer P to scrub the surface. Alternatively, a pressurized cleaning liquid may be used for surface cleaning. Furthermore, the cleaning device 32 may be configured to clean the back surface W1b as well as the front surface W1a of the first wafer W1.

[0057] The above wafer processing system 1 is provided with a control device 40 as a control unit. The control device 40 is, for example, a computer and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the overlapping wafers T in the wafer processing system 1. In addition, the program storage unit also stores a program for controlling the operation of the drive system of the various processing devices, conveying devices, etc. mentioned above to realize the wafer processing described later in the wafer processing system 1. In addition, the above program can be a program recorded in a computer-readable storage medium H and installed in the control device 40 from the storage medium H.

[0058] Next, the above-mentioned laser irradiation device 31 will be described.

[0059] like Figure 4 and Figure 5 As shown, the laser irradiation device 31 has a suction cup 100 as a holding portion for holding the overlapping wafer T by its upper surface. The suction cup 100 sucks and holds the entire back side W1b of the first wafer W1. In addition, the suction cup 100 can also suck and hold a portion of the back side W1b. The suction cup 100 is provided with lifting pins (not shown) for supporting the overlapping wafer T from below and raising and lowering it. The lifting pins pass through through holes (not shown) formed in a manner penetrating the suction cup 100 and are configured to be freely raised and lowered.

[0060] The suction cup 100 is supported on the slider stage 102 via an air bearing 101. A rotation mechanism 103 is provided on the lower surface side of the slider stage 102. The rotation mechanism 103 has a built-in motor as a driving source. The suction cup 100 is configured to be freely rotatable around the θ axis (vertical axis) via the air bearing 101 by the rotation mechanism 103. The slider stage 102 is configured to be movable along a guide rail 105 provided on a base 106 and extending in the Y-axis direction by a moving mechanism 104 provided on its lower surface. In addition, there is no particular limitation on the driving source of the moving mechanism 104, and for example, a linear motor is used.

[0061] A laser irradiation unit 110 is provided above the suction cup 100. The laser irradiation unit 110 includes a laser head 111, an optical system 112, and a lens 113. The laser head 111 oscillates laser light in a pulsed manner. The optical system 112 controls the intensity and position of the laser light or adjusts the output by attenuating the laser light. The lens 113 is a cylindrical component for irradiating the overlapping wafer T held by the suction cup 100 with laser light. In the present embodiment, the laser light is a CO2 laser, and the laser light emitted from the laser irradiation unit 110 passes through the second wafer W2 and is irradiated on the laser absorption layer P. In addition, the wavelength of the CO2 laser light is, for example, 8.9 μm to 11 μm. In addition, the lens 113 is configured to be freely raised and lowered by a lifting mechanism (not shown).

[0062] In addition, a conveying pad 120 serving as a conveying portion is provided above the suction cup 100. The conveying pad 120 is configured to be freely raised and lowered by a lifting mechanism (not shown). In addition, the conveying pad 120 has an adsorption surface for the second wafer W2. Moreover, the conveying pad 120 conveys the second wafer W2 between the suction cup 100 and the conveying arm 23. Specifically, after the suction cup 100 is moved to the bottom of the conveying pad 120 (the handover position with the conveying arm 23), the conveying pad 120 adsorbs and holds the back side W2b of the second wafer W2 to peel it off from the first wafer W1. Next, the peeled second wafer W2 is handed over from the conveying pad 120 to the conveying arm 23 and is carried out from the laser irradiation device 31. In addition, the conveying pad 120 can be configured to flip the front and back of the wafer by a flipping mechanism (not shown).

[0063] exist Figure 5 In the laser irradiation device 31 shown in FIG. 1 , the conveying arm 23 accesses the conveying pad 120 from the positive direction side of the X axis. Figure 5 The laser irradiation device 31 shown is rotated 90 degrees counterclockwise, and the transfer arm 23 accesses the transfer pad 120 from the Y-axis negative direction side.

[0064] When the overlapped wafer T is loaded into the laser irradiation device 31, the overlapped wafer T is transferred from the transfer arm 23 to the lift pins, and the lift pins are lowered to place the overlapped wafer T on the suction cup 100. Furthermore, when the peeled second wafer W2 is unloaded from the laser irradiation device 31, the overlapped wafer T placed on the suction cup 100 is raised by the lift pins and transferred from the lift pins to the transfer arm 23.

[0065] Next, wafer processing using the wafer processing system 1 configured as above will be described. In this embodiment, the first wafer W1 and the second wafer W2 are previously bonded to form a superposed wafer T in a bonding device (not shown) outside the wafer processing system 1 .

[0066] First, the cassette Ct storing a plurality of superimposed wafers T is placed on the cassette mounting table 11 of the loading / unloading block 10 .

[0067] Next, the wafer transfer device 22 removes the overlapped wafer T from the cassette Ct and transfers it to the laser irradiation device 31. In the laser irradiation device 31, the overlapped wafer T is transferred from the transfer arm 23 to the lift pins, and the chuck 100 suction-holds the overlapped wafer T. Next, the chuck 100 is moved to the processing position by the moving mechanism 104. This processing position is a position where the laser irradiation unit 110 can irradiate the overlapped wafer T (laser absorption layer P) with laser light.

[0068] Then, if Figure 6 and Figure 7As shown, laser light L (CO2 laser) is pulsed from the laser irradiation unit 110 toward the laser absorption layer P, more specifically, the boundary between the laser absorption layer P and the second wafer W2. At this time, the laser light L passes through the second wafer W2 from the back surface W2b side and is absorbed by the laser absorption layer P. Furthermore, this laser light L causes delamination at the boundary between the laser absorption layer P and the second wafer W2. Furthermore, the laser light L is almost entirely absorbed by the laser absorption layer P and does not reach the device layer D2. Therefore, damage to the device layer D2 can be suppressed.

[0069] When irradiating the laser absorption layer P with the laser beam L, the chuck 100 (overlapping 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. Thus, the laser absorption layer P is irradiated with the laser beam L from the radial outside toward the radial inside, and as a result, the laser beam is irradiated in a spiral shape from the outside toward the inside. Figure 7 The black arrow shown indicates the rotation direction of the suction cup 100 .

[0070] The irradiation start position of the laser light L is preferably between the outer peripheral end Ea of the second wafer W2 and the joint end Eb of the first wafer W1 and the second wafer W2 in the superimposed wafer T. In this case, for example, even if the center of the first wafer W1 and the center of the second wafer W2 are offset and eccentric in the superimposed wafer T, the eccentricity can be absorbed, and the laser light L can be appropriately irradiated onto the laser absorption layer P.

[0071] In addition, if Figure 8 As shown, the laser light L may be irradiated concentrically and annularly in the laser absorption layer P. However, in this case, since the rotation of the chuck 100 and the movement of the chuck 100 in the Y direction are performed alternately, the spiral irradiation of the laser light L as described above can shorten the irradiation time and improve productivity.

[0072] Alternatively, the laser light L may be irradiated from the radially inner side toward the radially outer side of the laser absorption layer P. However, in this case, since the inner side of the laser absorption layer P peels off first, the stress generated by the peeling is directed radially outward, potentially causing peeling of the outer portion not irradiated by the laser light L. Regarding this point, irradiating the laser light L from the radially outer side toward the radially inner side as described above allows the stress generated by the peeling to be released outward, making it easier to control the peeling. Furthermore, by properly controlling the peeling, roughness of the peeled surface can be suppressed.

[0073] In this embodiment, the chuck 100 is rotated when the laser absorption layer P is irradiated with the laser light L. However, the lens 113 may be moved to rotate relative to the chuck 100. Furthermore, the chuck 100 is moved in the Y-axis direction, but the lens 113 may also be moved in the Y-axis direction.

[0074] In this way, in the laser irradiation device 31, the laser light L is irradiated to the laser absorption layer P. Moreover, since the laser light L is irradiated in a pulsed manner, the peak power of the laser light L can be increased. Figure 1 As described above, separation can occur at the boundary between the laser absorption layer P and the second wafer W2 , and the second wafer W2 can be appropriately separated from the laser absorption layer P.

[0075] Then, the suction cup 100 is moved to the handover position by the moving mechanism 104. Figure 9 As shown in (a), the back side W2b of the second wafer W2 is adsorbed and held by the transfer pad 120. Figure 9 As shown in (b), while the transfer pad 120 is sucking and holding the second wafer W2, the transfer pad 120 is raised to peel the second wafer W2 from the laser absorption layer P. At this time, as described above, the laser light L is irradiated to cause separation at the boundary between the laser absorption layer P and the second wafer W2, so the second wafer W2 can be peeled from the laser absorption layer P without applying a large load.

[0076] The peeled second wafer W2 is transferred from the transfer pad 120 to the transfer arm 23 of the wafer transfer device 22 and transferred to the cassette Cw2 on the cassette stage 11. Alternatively, before transferring the second wafer W2 removed from the laser irradiation device 31 to the cassette Cw2, the second wafer W2 may be transferred to the cleaning device 32 to clean its peeled surface, i.e., the surface W2a. In this case, the transfer pad 120 may be used to flip the second wafer W2 over and transfer it to the transfer arm 23.

[0077] Meanwhile, the first wafer W1 held by the suction cup 100 is lifted from the suction cup 100 by the lifting pins, transferred to the transfer arm 23, and transported to the cleaning device 32. In the cleaning device 32, the surface of the laser absorption layer P, which serves as the peeling surface, is scrubbed. Furthermore, the back surface W1b of the first wafer W1 can be cleaned together with the surface of the laser absorption layer P in the cleaning device 32. Separate cleaning sections for cleaning the surface of the laser absorption layer P and for cleaning the back surface W1b of the first wafer W1 can be provided.

[0078] Thereafter, the first wafer W1 that has been subjected to all the processes is transferred to the cassette Cw1 on the cassette stage 11 by the wafer transfer device 22. In this manner, a series of wafer processes in the wafer processing system 1 is completed.

[0079] According to the above embodiment, the laser irradiation device 31 irradiates the laser absorption layer P with pulsed laser light L, thereby increasing the peak power of the laser light L. As a result, delamination can be achieved at the boundary between the laser absorption layer P and the second wafer W2. Furthermore, when irradiating the laser light L in pulsed form, the thermal impact is reduced compared to using a continuous wave, enabling stable laser delamination. Consequently, the second wafer W2 can be properly delaminated from the laser absorption layer P, allowing the device layer D2 to be transferred to the first wafer W1.

[0080] Here, in order to uniformly peel the first wafer W1 and the second wafer W2 within the wafer surface, it is preferable to keep the interval of the irradiated laser L, that is, the interval of the pulses, fixed. However, in order to keep the interval of the pulses fixed, when the suction cup 100 (overlapping wafer T) is rotated, the rotation speed of the suction cup 100 becomes faster as the laser L moves from the radial outside to the radial inside. In this case, when the rotation speed of the suction cup 100 reaches the upper limit, the interval of the laser L becomes smaller as the irradiation position of the laser L moves radially inward, and sometimes the laser L may overlap at the center. Therefore, it is necessary to adjust the irradiation interval of the laser L, for example, there are two methods as follows.

[0081] The first method is to control the rotation speed of the chuck 100. Specifically, when the irradiation position of the laser light L is radially outside the laser absorption layer P, the rotation speed is slowed down, and when the irradiation position of the laser light L is radially inside, the rotation speed is increased. The specific adjustment of the rotation speed can be arbitrarily set according to the frequency of the laser light L. In this case, the rotation speed of the chuck 100 can be kept constant, thereby maintaining a constant interval between irradiations of the laser light L.

[0082] The second method is to control the frequency of laser light L. Specifically, when the irradiation position of laser light L is radially outside the laser absorption layer P, the frequency is increased, and when the irradiation position of laser light L is radially inside, the frequency is decreased. Furthermore, the specific frequency adjustment can be arbitrarily set according to the rotation speed of chuck 100. In this case, the rotation speed of chuck 100 can also be kept constant to maintain a constant interval between irradiations of laser light L.

[0083] Furthermore, in order to shorten the processing time (takt) of laser irradiation and improve productivity, it is preferable to use high-frequency laser light L and maintain the rotation speed of the chuck 100 in the first method.

[0084] Alternatively, the first and second methods may be used in combination. In this case, the rotation speed of the chuck 100 is slowed down at radially outer positions, and the frequency of the laser light L is increased. Meanwhile, the rotation speed of the chuck 100 is accelerated at radially inner positions, and the frequency of the laser light L is decreased.

[0085] When controlling the frequency of laser light L in the second method, for example, when controlling the frequency of laser light L in the laser oscillator of laser head 111, it is necessary to adjust parameters by taking into account the output and pulse waveform of laser light L. For example, if the energy of laser light L required for ablation of the radially outer and radially inner sides of the laser absorption layer P is the same, increasing the frequency of laser light L on the outer side requires increasing the output, while decreasing the frequency of laser light L on the inner side requires decreasing the output. Furthermore, changing the frequency of laser light L in the laser oscillator also changes the pulse waveform of laser light L. Consequently, complex adjustments taking into account the output and pulse waveform of laser light L are required, making process control of the laser treatment difficult.

[0086] Therefore, in this embodiment, an acousto-optic modulator as an optical element is used to control the frequency of the laser light L. As described above, the laser irradiation unit 110 includes the laser head 111 , the optical system 112 , and the lens 113 .

[0087] like Figure 10 As shown, the laser head 111 includes a laser oscillator 130 that oscillates laser light in a pulsed manner. The frequency of the laser light oscillating from the laser oscillator 130 is the maximum frequency controllable by the acousto-optic modulator 131, which will be described later. Furthermore, the laser head 111 may include devices other than the laser oscillator 130, such as an amplifier.

[0088] The optical system 112 includes an acousto-optic modulator (AOM) 131 that redirects laser light from a laser oscillator 130 into different directions, and an attenuator 132, which attenuates the laser light from the laser oscillator 130 to adjust the laser output. The AOM 131 and attenuator 132 are arranged in the order shown, starting from the laser oscillator 130.

[0089] The acousto-optic modulator 131 is an optical modulator that controls the intensity and position of laser light electrically and at high speed. Figure 11As shown, when laser light L1 from laser oscillator 130 is incident on the acousto-optic modulator 131, a voltage is applied to change the refractive index of laser light L1, thereby redirecting the laser light L1 in different directions. Specifically, the angle of change of laser light L1 can be controlled by adjusting the voltage. In this embodiment, for example, laser light L1 is redirected into two different directions: laser light L2 in one direction is irradiated onto the laser absorption layer P, while laser light L3 in the other direction is not irradiated onto the laser absorption layer P. By controlling the redirection of laser light L2 and laser light L3, the frequency of laser light L2 irradiated onto the laser absorption layer P can be adjusted.

[0090] In this case, the frequency of the laser light L2 irradiated to the laser absorption layer P can be adjusted by thinning out the pulses of the laser light L1 using the acousto-optic modulator 131. For example, if the deflection ratio of the laser light L2 and the laser light L3 relative to the laser light L1 is set to 100:0 at a certain timing, the laser light L1 is directly irradiated to the laser absorption layer P as the laser light L2. On the other hand, if the deflection ratio of the laser light L2 and the laser light L3 relative to the laser light L1 is set to 0:100 at another timing, the laser light L2 is 0 (zero), and the laser light L2 is not irradiated to the laser absorption layer P. In this case, it is possible to Figure 12 The frequency of the laser light L1 from the laser oscillator 130 shown in (a) is adjusted Figure 12 The frequency of the laser light L2 after being redirected by the AOM 131 is shown in (b). As mentioned above, the frequency of the laser light L1 is the highest frequency that can be controlled by the AOM 131, so the frequency of the laser light L2 can be adjusted arbitrarily. Figure 12 The horizontal axis represents time, and the vertical axis represents the intensity of the laser L2. Figure 12 The density in the graph represents the frequency of the laser light L2.

[0091] Furthermore, in this case, since the frequency of laser light L1 oscillated from laser oscillator 130 remains unchanged, the pulse waveform of laser light L1 remains unchanged, and the pulse waveform of laser light L2 can also be the same as the pulse waveform of laser light L1. Therefore, the frequency of laser light L2 can be easily adjusted, eliminating the need for the complex adjustments previously described, thereby facilitating process control of the laser processing.

[0092] In this embodiment, the acousto-optic modulator 131 is used as the optical element, but the present invention is not limited to this. For example, an electro-optic modulator (EOM) can also be used as the optical element. In addition, optical deflectors such as an acousto-optic deflector (AOD) and an electro-optic deflector (EOD) can also be used.

[0093] Next, a method for controlling laser light L2 when irradiating the laser absorption layer P from the laser irradiation unit 110 will be described. As described above, when the irradiation position of laser light L2 is radially outside the laser absorption layer P, the frequency is increased, and when the irradiation position of laser light L2 is radially inside the laser absorption layer P, the frequency is decreased.

[0094] The following is an explanation using a specific example. The numerical values ​​in this specific example are merely illustrative and are not intended to limit this disclosure. For example, the energy required for peeling the laser absorption layer P radially outward and radially inward is set to 400 μJ. The required frequency of laser light L2 radially outward of the laser absorption layer P is set to 100 kHz, and the required frequency of laser light radially inward is set to 50 kHz. The frequency of laser light L1 from the laser oscillator 130 is 100 kHz, and the output is 40 W.

[0095] In this case, the pulses of laser light L1 from the laser oscillator 130 are not thinned out in the acousto-optic modulator 131 radially outward from the laser absorption layer P. Consequently, the frequency of laser light L2 irradiating the laser absorption layer P can be set to 100 kHz, the same as the frequency of laser light L1. Furthermore, the output of laser light L2 is also 40 W, the same as the output of laser light L1. Furthermore, the energy of laser light L2 is 400 μJ (= 40 W / 100 kHz), enabling proper ablation.

[0096] Meanwhile, the acousto-optic modulator 131 thins out half of the pulses of laser light L1 emitted from the laser oscillator 130 radially inward of the laser absorption layer P. This allows the frequency of laser light L2 irradiating the laser absorption layer P to be set to 50 kHz, half the frequency of laser light L1. Furthermore, thinning out laser light L1 reduces the output of laser light L2 to 20 W, half the output of laser light L1. This reduces the energy of laser light L2 to 400 μJ (= 20 W / 50 kHz), enabling proper ablation.

[0097] In this manner, the rotational speed of chuck 100 is controlled based on the frequency and irradiation position of laser light L2 to maintain a constant pulse interval. Furthermore, the maximum rotational speed of chuck 100 is maintained at the center of laser absorption layer P, and acousto-optic modulator 131 adjusts the frequency of laser light L2 based on this maximum rotational speed. This allows laser processing to be performed while maintaining the maximum possible rotational speed of chuck 100 and the high frequency of laser light L2, thereby achieving high-productivity laser processing.

[0098] Furthermore, in this case, since the frequency of laser light L1 from laser oscillator 130 remains unchanged, the pulse waveform of laser light L1 remains unchanged, and the pulse waveform of laser light L2 can also be the same as that of laser light L1. Therefore, the frequency of laser light L2 can be easily adjusted, enabling continuous, seamless processing. As a result, process control of the laser processing becomes easier, enabling a stable process.

[0099] In this embodiment, the output of laser light L1 from laser oscillator 130 is 40 W, so there is no need to adjust the output to the energy of 400 μJ required for ablation. For example, if the output of laser light L1 is 50 W, the output of laser light L1 can be adjusted by attenuating it by 20% using attenuator 132.

[0100] In the laser irradiation unit 110 of the above embodiment, the acousto-optic modulator 131 is provided at a position upstream of the attenuator 132 inside the optical system 112, but the installation position is not limited thereto. Figure 13 As shown in FIG. 1 , the acousto-optic modulator 131 is disposed downstream of the attenuator 132 within the optical system 112. Alternatively, for example, Figure 14 As shown, the AOM 131 is installed at a position downstream of the laser oscillator 130 inside the laser head 111. Alternatively, the AOM 131 may be installed at two or more of the above-mentioned installation positions.

[0101] Furthermore, in the laser irradiation section 110, after the frequency and output of the laser light L2 are adjusted by the acousto-optic modulator 131, the output can be fine-tuned by the attenuator 132. Here, the output of the laser light L1 oscillated from the laser oscillator 130 sometimes deviates due to individual differences of the laser oscillator 130. In the attenuator 132, such deviations in the output can be adjusted. In addition, while the output of the laser light L1 from the laser oscillator 130 is always monitored, the attenuator 132 can be feedback-controlled to adjust the output. Moreover, from the viewpoint of fine-tuning the output of the laser light L2 by the attenuator 132 as described above, it is preferable to Figure 10 As shown, the acousto-optic modulator 131 is provided at a position upstream of the attenuator 132 .

[0102] In the laser irradiation unit 110 of the above embodiment, the attenuator 132 can be omitted. For example, the output of laser light L2 can be adjusted using the acousto-optic modulator 131 instead of the attenuator 132. For example, if the output of laser light L1 is 50W and the output of laser light L2 required for ablation is 40W, the output of laser light L2 can be adjusted to 40W by setting the deflection ratio of laser light L2 and laser light L3 relative to laser light L1 to 80:20 in the acousto-optic modulator 131.

[0103] In the above embodiment, laser absorption layer P is irradiated with laser light L in a spiral or concentric pattern. However, the irradiation pattern of laser light L is not limited to this. Furthermore, the configuration of the device corresponding to these various irradiation patterns is not limited to the laser irradiation device 31 of the above embodiment. In the above-described laser irradiation device 31, chuck 100 is rotatable about the θ-axis and movable along one axial direction (the Y-axis), but may also be movable along two axes (the X-axis and the Y-axis).

[0104] Figure 15 and Figure 16 The laser irradiation device 200 shown is a device that moves the suction cup 100 along two axes (X-axis and Y-axis). The laser irradiation device 200 has a suction cup 210 as a holding portion that holds the overlapping wafer T by its upper surface. The suction cup 210 adsorbs and holds the back surface W1b of the first wafer W1. The suction cup 210 is provided with lifting pins (not shown) for supporting the overlapping wafer T from below and raising and lowering the overlapping wafer T. The lifting pins pass through through holes (not shown) formed in a manner that penetrates the suction cup 210 and are configured to be freely raised and lowered.

[0105] The suction cup 210 is supported on the slider stage 212 via an air bearing 211. A rotation mechanism 213 is provided on the lower surface side of the slider stage 212. The rotation mechanism 213 has a built-in motor as a driving source. The suction cup 210 is configured to be freely rotatable around the θ axis (vertical axis) via the air bearing 211 through the rotation mechanism 213. The slider stage 212 is configured to be movable along a guide rail 215 provided on a moving stage 216 and extending in the Y-axis direction through a moving mechanism 214 provided on its lower surface. In addition, the driving source of the moving mechanism 214 is not particularly limited, and for example, a linear motor is used.

[0106] The movable stage 216 is configured to move along a guide rail 217, which is provided on a base 218 and extends along the X-axis, via a moving mechanism (not shown) provided on its underside. The driving source of the moving mechanism is not particularly limited; for example, a linear motor may be used. This configuration allows the suction cup 210 to rotate freely about the θ-axis and to move freely along the X- and Y-axes.

[0107] A laser irradiation unit 220 is provided above the chuck 210. The laser irradiation unit 220 includes a laser head 221, an optical system 222, and a lens 223. The laser head 221 oscillates laser light L in a pulsed manner. The optical system 222 adjusts the output of the laser light L by controlling the intensity and position of the laser light L or by attenuating the laser light L. The lens 223 is a cylindrical member for irradiating the superimposed wafer T held by the chuck 210 with laser light L, such as a CO2 laser. The lens 223 is configured to be freely raised and lowered by a lifting mechanism (not shown).

[0108] The laser head 221 uses, for example, a galvanometer. Multiple galvanometer mirrors (not shown) are arranged inside the laser head 221. Furthermore, an f-θ lens is used as the lens 223. With this structure, laser light L input to the laser head 221 is reflected by the galvanometer mirrors, propagates through the optical system 222 to the lens 223, passes through the second wafer W2, and is irradiated onto the laser absorption layer P. Furthermore, by adjusting the angle of the galvanometer mirrors, the laser light L can be scanned within the laser absorption layer P.

[0109] Furthermore, a transfer pad 230 serving as a transfer unit is provided above the suction cup 210. The transfer pad 230 is configured to be freely movable by a lifting mechanism (not shown). The structure of the transfer pad 230 is the same as that of the transfer pad 120 of the above embodiment.

[0110] In the laser irradiation apparatus 200, the overlapped wafer T is transferred from the transfer arm 23 to the lift pins, and the chuck 210 is caused to suck and hold the overlapped wafer T. Next, the chuck 210 is moved to a processing position by the moving mechanism 214 and the moving stage 216. This processing position is a position where the laser beam L can be irradiated from the laser irradiation unit 220 onto the overlapped wafer T (laser absorption layer P).

[0111] Then, if Figure 17 As shown, the laser irradiation unit 220 irradiates the laser absorption layer P with pulsed laser light L. At this time, the laser light L passes through the second wafer W2 from the back surface W2b side of the second wafer W2 and is absorbed in the laser absorption layer P.

[0112] When the laser light L is irradiated to the laser absorption layer P, the laser light L is scanned within a predetermined range A ( Figure 17 ) is scanned. Next, while irradiation with laser light L is stopped, the suction cup 210 is moved in the X-axis direction. By repeating the irradiation and scanning with laser light L, and the movement of the suction cup 210 in this manner, laser light L is irradiated in a row in the X-axis direction. Next, the suction cup 210 is moved so as to be staggered in the Y-axis direction, and the irradiation and scanning with laser light L, and the movement of the suction cup 210 are repeated in the same manner as above, so that laser light L is irradiated in a row in the X-axis direction. Thus, the laser light L is irradiated onto the laser absorption layer P.

[0113] In this embodiment, when irradiating the laser absorption layer P with the laser light L, the chuck 210 is moved in the X-axis and Y-axis directions. However, the lens 223 may be moved to move relative to the chuck 210 .

[0114] Next, the chuck 210 is moved to the transfer position by the moving mechanism 214 and the moving stage 216. Then, the back surface W2b of the second wafer W2 is sucked and held by the transfer pad 230, and the transfer pad 230 is raised to separate the second wafer W2 from the laser absorption layer P.

[0115] This embodiment also achieves the same effects as the above-described embodiment. Specifically, since the laser light L is irradiated onto the laser absorption layer P in a pulsed manner, the peak power of the laser light L can be increased. As a result, delamination can be appropriately generated at the boundary between the laser absorption layer P and the second wafer W2. Furthermore, since the laser light L can be irradiated at a uniform density throughout the scanning range A, the laser light L can be uniformly irradiated onto the laser absorption layer P.

[0116] Furthermore, in this embodiment, there may be a plurality of laser irradiation units 220. In this case, the laser absorption layer P can be irradiated with a plurality of laser beams L, thereby shortening the processing time and further improving productivity.

[0117] In the above embodiment, the irradiation and scanning of the laser L and the movement of the suction cup 210 are repeated, but it is also possible to Figure 18 As shown, the chuck 210 is moved in a row in the X-axis direction while being irradiated and scanned with the laser light L. After irradiating the row in the X-axis direction with the laser light L, the chuck 210 is moved in a staggered manner in the Y-axis direction to irradiate the laser absorption layer P with the laser light L.

[0118] This embodiment also achieves the same effects as the above-described embodiment. Specifically, since the laser absorption layer P is irradiated with laser light L in a pulsed manner, delamination can be appropriately generated at the boundary between the laser absorption layer P and the second wafer W2. Furthermore, since the irradiation and scanning of laser light L are not stopped within a row in the X-axis direction, the laser irradiation processing time can be shortened, further improving productivity.

[0119] The irradiation of the laser light L in the spiral (or concentric) manner in the above embodiment and the irradiation and scanning of the laser light L may be combined.

[0120] When rotating the chuck 210 (overlapping wafer T) as described above, in order to maintain a constant pulse interval, the rotation speed of the chuck 210 increases as the laser light L moves from the radially outer side to the radially inner side. Therefore, in the above embodiment, the irradiation interval of the laser light L is adjusted by controlling at least the rotation speed or frequency of the chuck 210.

[0121] In contrast, if Figure 19 As shown, while the chuck 210 is rotated, the irradiation position of the laser light L is moved from the radially outer side to the radially inner side, thereby spirally irradiating the outer periphery of the laser absorption layer P with the laser light L. When the rotation speed of the chuck 210 reaches its upper limit, the rotation of the chuck 210 is stopped at the center of the laser absorption layer P, and the laser light L is scanned while being irradiated within the scanning range A. While the scanning range A is illustrated as a square, the shape of the scanning range A is not limited thereto. For example, the scanning range A may also be circular.

[0122] By changing the irradiation pattern of the laser light L at the outer periphery and the center of the laser absorption layer P in this manner, it is possible to prevent the laser light L from overlapping and to keep the interval between irradiation laser light L, i.e., the pulse interval, constant. As a result, the first wafer W1 and the second wafer W2 can be separated uniformly within the wafer surface.

[0123] Furthermore, when the irradiation range of the laser light L of the laser irradiation unit 220 is large, for example, when the irradiation range is larger than the diameter of the laser absorption layer P, the entire surface of the laser absorption layer P can be irradiated with the laser light L at once.

[0124] In the laser irradiation device 31 of the above embodiment, it is also possible to Figure 20 As shown, a guide portion 240 and a holding member 250 are provided on the upper surface of the suction cup 100 .

[0125] like Figure 21 As shown, the guide portion 240 is used to guide the overlapped wafer T to the suction cup 100. The guide portion 240 includes a vertical portion 241 extending vertically upward from the suction cup 100, and an inclined portion 242 whose diameter increases upward from the vertical portion 241. The inner diameter of the vertical portion 241 is slightly larger than the diameter of the overlapped wafer T. Furthermore, the overlapped wafer T disposed above the suction cup 100 is centered by the inclined portion 242, and is then guided to the vertical portion 241 and held by the suction cup 100.

[0126] like Figure 22 and Figure 23As shown, the holding member 250 extends vertically upward from the upper surface of the suction cup 100 and is used to hold the side of the second wafer W2. The holding member 250 is arranged at multiple positions, for example, three positions, on the concentric circle of the suction cup 100. The holding member 250 is configured to move forward and backward freely in a manner of contacting or separating relative to the second wafer W2 through a moving mechanism 251. In addition, the holding member 250 is configured to rotate freely as a whole with the suction cup 100. Moreover, by holding the second wafer W2 by the holding member 250, the position of the second wafer W2 can be prevented from being shifted or slipping. In addition, a cutout portion 243 is formed at a position corresponding to the holding member 250 in the guide portion 240, and the holding member 250 moves in the cutout portion 243, thereby not interfering with the guide portion 240.

[0127] In addition, in this embodiment, both the guide portion 240 and the holding member 250 are provided, but only the guide portion 240 or only the holding member 250 may be provided. In the case where only the guide portion 240 is provided, the positional deviation and sliding of the second wafer W2 can be suppressed by the vertical portion 241. In particular, the guide portion 240 is useful when the gap between the vertical portion 241 and the second wafer W2 is within the allowable range of positional deviation. However, in the case where both the guide portion 240 and the holding member 250 are provided, the effect of centering the overlapping wafer T and preventing the positional deviation and sliding of the second wafer W2 is improved.

[0128] In this case, when the overlapped wafer T is held on the chuck 100 at the transfer position, the three holding members 250 retreat to a position where they do not contact the second wafer W2. After the chuck 100 holding the overlapped wafer T is moved to the processing position, the three holding members 250 are moved to a position where they contact the side surfaces of the second wafer W2, and the second wafer W2 is held by these holding members 250.

[0129] Here, in the absence of the guide portion 240 and the retaining member 250, when laser light L is irradiated in a spiral pattern from the radially outer side to the radially inner side of the laser absorption layer P, as peeling progresses, the rotation of the suction cup 100 exerts a centrifugal force on the second wafer W2, causing the second wafer W2 to shift relative to the laser absorption layer P. This could result in laser light L being irradiated to a location other than the target location during laser processing. Furthermore, there is a risk that the second wafer W2 may slip after peeling. In this regard, in this embodiment, the retaining member 250 holds the second wafer W2, thereby preventing the second wafer W2 from shifting or slipping.

[0130] Next, after irradiation with laser light L, when the suction cup 100 is moved to the transfer position, the second wafer W2 is also held by the holding member 250. During the movement of the suction cup 100, an inertial force acts on the second wafer W2, potentially causing the second wafer W2 to shift relative to the laser absorption layer P. In this case, when the back surface W2b of the second wafer W2 is subsequently sucked and held by the transfer pad 120, it cannot be sucked and held in the proper position. Therefore, in this embodiment, the second wafer W2 is also held by the holding member 250 during the movement of the suction cup 100 to prevent the second wafer W2 from shifting.

[0131] Furthermore, the structure of the holding member that holds the second wafer W2 is not limited to the structure of the holding member 250 described above. For example, the holding member may hold the second wafer W2 by clamping the upper surface and side surfaces of the second wafer W2 from the side. Furthermore, the holding member may hold the second wafer W2 from midway through the laser processing. Furthermore, if the holding member is made of a material that transmits the laser light L, such as silicon, it can hold the upper surface of the second wafer W2.

[0132] While the wafer processing system 1 in the above embodiment includes a cleaning device 32, the wafer processing system 1 may also include an etching device (not shown). The etching device etches the surface W1a of the first wafer W1 after peeling, specifically, the surface of the laser absorption layer P. For example, after the surface of the laser absorption layer P is scrubbed by the cleaning device 32, a chemical solution (etching solution) is supplied to the surface of the laser absorption layer P to wet-etch the surface. Furthermore, the wafer processing system 1 may include either the cleaning device 32 or the etching device.

[0133] Furthermore, the wafer processing system 1 of the above embodiment may include a CMP device (not shown). In the CMP device, a CMP (Chemical Mechanical Polishing) process is performed on the surface W1a of the first wafer W1 after peeling, specifically, the surface of the laser absorption layer P. For example, after the surface of the laser absorption layer P is scrubbed by the cleaning device 32, the CMP process is performed on the surface of the laser absorption layer P to flatten the surface of the laser absorption layer P. Furthermore, the CMP device may be located external to the wafer processing system 1.

[0134] In the above embodiment, the laser light L is irradiated to the boundary between the laser absorption layer P and the second wafer W2 to separate the second wafer W2 from the laser absorption layer P. However, for example, Figure 24 As shown, the lift-off is performed so that the laser absorption layer P remains on the second wafer W2 .

[0135] In this case, in the laser irradiation device 31, as shown in FIG. Figure 24 As shown in (a), the boundary between the laser absorption layer P and the device layer D2 is irradiated with pulsed laser light L from the laser irradiation unit 110. Then, the laser light L causes peeling at the boundary between the laser absorption layer P and the device layer D2.

[0136] Furthermore, by controlling the energy density of the laser light L required for exfoliation of the laser light absorbing layer P according to the film type of the laser light absorbing layer P, the absorption position of the laser light L, that is, the exfoliation position of the laser light absorbing layer P, can be adjusted. For example, by changing the original output of the laser light L, for example, by adjusting the focal numerical aperture (NA) of the laser irradiation unit 110 or by changing the focus position of the laser light L, the energy density of the laser light L can be adjusted.

[0137] Next, while the back surface W2b of the second wafer W2 is being sucked and held by the transfer pad 120, as shown in FIG. Figure 24 As shown in (b), the transfer pad 120 is raised to peel the laser absorption layer P from the device layer D2.

[0138] This embodiment also achieves the same effects as the above-described embodiment. Specifically, since the laser light L is pulsed onto the laser absorption layer P, the peak power of the laser light L can be increased. Consequently, delamination can be appropriately generated at the boundary between the laser absorption layer P and the device layer D2. Furthermore, the laser absorption layer P remaining on the second wafer W2 is an oxide film (SiO2 film). For example, in subsequent semiconductor manufacturing processes, this laser absorption layer P can be used as an oxide film (insulating film) when forming TSVs (Through-Silicon Vias) on the second wafer W2.

[0139] In this embodiment, the surface of the laser absorption layer P on the second wafer W2 after peeling can be scrubbed and then subjected to CMP in the aforementioned CMP apparatus. In this case, the surface of the laser absorption layer P can be flattened. Furthermore, as described above, it can be suitably used as an oxide film (insulating film) when forming TSVs.

[0140] In the above embodiments, the Figure 2 The case of processing the overlapped wafer T shown in FIG. 1 is shown in FIG. 2 , but the processing object is not limited to this. Figures 25 to 28 The following describes the processing of different types of overlapped wafers T.

[0141] For processing Figure 25 The case of overlapping wafer T shown in FIG. Figure 25As shown in (a), the laser absorption layer P1 formed between the second wafer W2 and the device layer D2 is formed inside the second wafer W2. The second wafer W2 is, for example, an SOI substrate, and the laser absorption layer P1 is, for example, an oxide film (SiO2 film). That is, Si as the second wafer W2, the SiO2 film as the laser absorption layer P1, and Si as the Si film S are sequentially stacked. In addition, the laser absorption layer P1 can be any film that is peeled off at the boundary with the Si film S. Films other than oxide films (SiO2 films), such as silicon germanium (SiGe) or germanium (Ge), may also be used.

[0142] Then, if Figure 25 As shown in (b), a device layer D2 and a surface film F2 are formed on the surface of the laser absorption layer P1. The device layer D2 and the surface film F2 are formed through a normal substrate process (FEOL) and wiring process (BEOL).

[0143] Then, if Figure 25 As shown in (c), the first wafer W1 and the second wafer W2 are bonded together. A surface film F1 is formed on the surface W1a of the first wafer W1, and the surface film F1 and the surface film F2 are bonded together.

[0144] Next, in the laser irradiation device 31 of the wafer processing system 1, as shown in FIG. Figure 25 As shown in (d), the laser irradiation unit 110 irradiates the boundary between the laser absorption layer P1 and the Si film S with pulsed laser light L. Then, the laser light L causes peeling at the boundary between the laser absorption layer P1 and the Si film S.

[0145] Next, while the back surface W2b of the second wafer W2 is being sucked and held by the transfer pad 120, as shown in FIG. Figure 25 As shown in (e), the transfer pad 120 is raised to peel the laser absorption layer P1 from the Si film S.

[0146] In addition, in this embodiment, the peeling position of the laser absorption layer P1 may be different from the Figure 24 In the illustrated case, the absorption position of the laser light L, that is, the peeling position of the laser absorption layer P1 is similarly adjusted to cause peeling at the boundary between the second wafer W2 and the laser absorption layer P1 .

[0147] For processing Figure 26 The case of overlapping wafer T shown in FIG. Figure 26 As shown in (a) and (b), between the second wafer W2 and the device layer D2, a laser absorption layer P2 formed of silicon germanium (SiGe) and a Si film S formed of Si are stacked in this order from the second wafer W2 side.

[0148] Then, if Figure 26As shown in (b), a device layer D2 and a surface film F2 are formed on the surface of the Si film S.

[0149] Then, if Figure 26 As shown in (c), the first wafer W1 and the second wafer W2 are bonded together. A device layer D1 and a surface film F1 are formed on the surface W1a of the first wafer W1, and the surface film F1 and the surface film F2 are bonded together.

[0150] Next, in the laser irradiation device 31 of the wafer processing system 1, as shown in FIG. Figure 26 As shown in (d), the laser irradiation unit 110 irradiates the boundary between the laser absorption layer P2 and the Si film S with pulsed laser light L. Then, the laser light L causes peeling at the boundary between the laser absorption layer P2 and the Si film S.

[0151] Then, if Figure 26 As shown in (e), while the back side W2b of the second wafer W2 is held by the transfer pad 120, the transfer pad 120 is raised to peel the laser absorption layer P2 from the Si film S. In addition, in this embodiment, the peeling position of the laser absorption layer P2 can also be different from the position of the laser absorption layer P2. Figure 24 In the illustrated case, the absorption position of the laser light L, that is, the separation position of the laser absorption layer P2 is adjusted similarly to cause separation at the boundary between the second wafer W2 and the laser absorption layer P2.

[0152] For processing Figure 27 The case of overlapping wafer T shown in FIG. Figure 27 As shown in (a) and (b), between the second wafer W2 and the device layer D2, a laser absorption layer P3 formed by an oxide film (SiO2 film), a SiGe film S1 formed by SiGe, and a Si film S2 formed by Si are stacked in sequence starting from the second wafer W2 side.

[0153] Then, if Figure 27 As shown in (b), a device layer D2 and a surface film F2 are formed on the surface of a Si film S2 formed of Si.

[0154] Then, if Figure 27 As shown in (c), the first wafer W1 and the second wafer W2 are bonded together. A device layer D1 and a surface film F1 are formed on the surface W1a of the first wafer W1, and the surface film F1 and the surface film F2 are bonded together.

[0155] Next, in the laser irradiation device 31 of the wafer processing system 1, as shown in FIG. Figure 27 As shown in (d), the laser irradiation unit 110 irradiates the boundary between the laser absorption layer P3 and the second wafer W2 with pulsed laser light L. The laser light L causes delamination at the boundary between the laser absorption layer P3 and the second wafer W2.

[0156] Then, if Figure 27 As shown in (e), while the back surface W2b of the second wafer W2 is being sucked and held by the transfer pad 120, the transfer pad 120 is moved upward to separate the second wafer W2 from the laser absorption layer P3.

[0157] For processing Figure 28 The overlapping wafer T shown in FIG. 1 is a structure in which Ge-pMOS is stacked on Si-nMOS. Figure 28 As shown in (a), a device layer D1 and a surface film F1 are formed on the surface W1a of the first wafer W1. That is, the first wafer W1 is a Si-nMOS.

[0158] Then, if Figure 28 As shown in (b), the first wafer W1 is bonded to the second wafer W2, which is a Ge-pMOS. On the surface W2a of the second wafer W2, a laser absorption layer P4 formed of an oxide film (SiO2 film), a device layer D2 formed of Ge, and a surface film F2 are stacked in order from the second wafer W2 side.

[0159] Then, if Figure 28 As shown in (b), the first wafer W1 and the second wafer W2 are bonded together. Specifically, the surface film F1 and the surface film F2 are bonded together.

[0160] Next, in the laser irradiation device 31 of the wafer processing system 1, as shown in FIG. Figure 28 As shown in (c), the boundary between the laser absorption layer P4 and the device layer D2 is irradiated with pulsed laser light L from the laser irradiation unit 110. Then, the laser light L causes peeling at the boundary between the laser absorption layer P4 and the device layer D2.

[0161] Then, if Figure 28 As shown in (d), while the back side W2b of the second wafer W2 is held by the transfer pad 120, the transfer pad 120 is raised to peel the laser absorption layer P4 from the device layer D2. In addition, in this embodiment, the peeling position of the laser absorption layer P4 can also be different from the position of the laser absorption layer P4. Figure 24 Similarly to the case of , the absorption position of the laser light L, that is, the peeling position of the laser absorption layer P4 is adjusted to cause peeling at the boundary between the second wafer W2 and the laser absorption layer P4.

[0162] above Figures 25 to 28 Any of the processing targets shown can achieve the same effects as those of the above-described embodiment.

[0163] In the overlapped wafer T processed by the above embodiment, it is also possible to Figure 29As shown, a reflective film R is provided between the laser absorption layer P and the device layer D2. Specifically, 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 with high reflectivity and a high melting point for the laser light L, such as a metal film. Furthermore, the device layer D2 is a functional layer, distinct from the reflective film R.

[0164] In this case, the laser light L emitted from the laser irradiation unit 110 passes through the second wafer W2 and is almost entirely absorbed by the laser absorption layer P. However, any unabsorbed laser light L 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.

[0165] In addition, 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.

[0166] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive, and the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope of the appended claims and the spirit thereof.

[0167] Description of Reference Numerals

[0168] 31: Laser irradiation device; 100: Suction cup; 110: Laser irradiation unit; D1, D2: Device layers; P: Laser absorption layer; T: Overlap wafer; W1: First wafer; W2: Second wafer.

Claims

1. A substrate processing method, comprising transferring a device layer formed on a second substrate to a first substrate in a superposed substrate formed by bonding a first substrate and a second substrate. A first surface film is formed on the first substrate. On the second substrate, a laser absorption layer, a second device layer, and a second surface film are formed in order from the surface side. The first surface film and the second surface film of the first substrate and the second substrate are bonded, The substrate processing method includes the following processes: irradiating the laser absorption layer with a pulsed laser beam from the back side of the second substrate; and The second substrate is peeled off from the first substrate at a boundary between the laser absorption layer and the second device layer, and the second device layer and the second surface film are transferred to the first substrate.

2. The substrate processing method according to claim 1, wherein: A first device layer is formed between the surface of the first substrate and the first surface film.

3. The substrate processing method according to claim 1 or 2, wherein: The second device layer is composed of Ge.

4. The substrate processing method according to claim 1 or 2, wherein: A reflective film is formed between the laser absorption layer and the second device layer.

5. The substrate processing method according to claim 1 or 2, wherein: irradiating the laser absorption layer with the laser from the radially outer side toward the radially inner side, The laser irradiation is started from a position between the outer peripheral end of the second substrate and the bonding end of the first substrate and the second substrate in the superimposed substrate, that is, the outer peripheral end of the laser absorption layer.

6. The substrate processing method according to claim 1 or 2, characterized in that: The laser absorption layer is annularly irradiated with the laser beam by alternately rotating the superposed substrate and moving the superposed substrate in a radial direction.

7. The substrate processing method according to claim 1 or 2, wherein: The first substrate is cleaned after the second substrate is peeled off.

8. The substrate processing method according to claim 1 or 2, wherein: The first substrate is etched after the second substrate is peeled off.

9. The substrate processing method according to claim 1 or 2, characterized in that: The first substrate is subjected to chemical mechanical polishing after the second substrate is peeled off.

10. The substrate processing method according to claim 1 or 2, wherein: The laser beam is irradiated while the superimposed substrate is rotated. The rotation speed of the overlapping substrate when the laser is irradiated radially inwardly of the laser absorption layer is faster than the rotation speed when the laser is irradiated radially outwardly of the laser absorption layer, and the frequency of the laser irradiated radially outwardly of the laser absorption layer is greater than the frequency of the laser irradiated radially inwardly of the laser absorption layer.

11. The substrate processing method according to claim 1 or 2, characterized in that: The first surface film is an oxide film, The second surface film is an oxide film.

12. A substrate processing apparatus for transferring a device layer formed on a surface of a first substrate to a second substrate in a superposed substrate formed by bonding the first substrate to the second substrate. A first surface film is formed on the first substrate. On the second substrate, a laser absorption layer, a second device layer, and a second surface film are formed in order from the surface side. The first surface film and the second surface film of the first substrate and the second substrate are bonded, The substrate processing device comprises: a holding portion that holds the back surface of the first substrate; a laser irradiation unit configured to irradiate the laser absorption layer with a laser beam in a pulsed manner from the back side of the second substrate while the holding unit holds the first substrate; a rotating mechanism that rotates the holding portion; a moving mechanism that moves the holding portion in a radial direction; and a control unit that controls the rotating mechanism, the moving mechanism, and the laser irradiation unit, The control unit controls the rotating mechanism, the moving mechanism, and the laser irradiation unit to alternately rotate the holding unit and move the holding unit in a radial direction, thereby irradiating the laser absorption layer with the laser in an annular shape.

13. A substrate processing system for transferring a device layer formed on a surface of a first substrate to a second substrate in a superposed substrate formed by bonding the first substrate to the second substrate. A first surface film is formed on the first substrate. On the second substrate, a laser absorption layer, a second device layer, and a second surface film are formed in order from the surface side. The first surface film and the second surface film of the first substrate and the second substrate are bonded, The substrate processing system comprises: a holding portion that holds the back surface of the first substrate; a laser irradiation unit configured to irradiate the laser absorption layer with a laser beam in a pulsed state from the back side of the second substrate while the holding unit holds the first substrate; and A conveying unit peels the second substrate from the first substrate at a boundary between the laser absorption layer and the second device layer, and transfers the second device layer and the second surface film to the first substrate.

14. The substrate processing system according to claim 13, wherein: A first device layer is formed between the surface of the first substrate and the first surface film.

15. The substrate processing system according to claim 13 or 14, characterized in that: The invention further comprises a cleaning device for cleaning the first substrate after the second substrate is peeled off.

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