Stripping device for silicon carbide wafer
By combining ultrasonic waves and magnetic suction devices, the problem of collisions caused by the irregular movement of silicon carbide wafers during the peeling process is solved, achieving efficient and non-destructive wafer separation and ensuring product quality and yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-04
- Publication Date
- 2026-04-14
AI Technical Summary
After silicon carbide wafers detach from silicon carbide ingots under ultrasonic waves, they move erratically and are prone to colliding with the inner wall of the receiving tank, resulting in scratches, chipping, and breakage, which affects product quality and yield.
By combining ultrasonic and magnetic devices, the wafer portion of the silicon carbide ingot is separated by ultrasonic resonance, and the wafer is attracted and fixed by the magnetic device to control its movement trajectory and avoid collision.
This effectively avoids scratches and damage to silicon carbide wafers during the stripping process, ensuring product quality and yield, and improving stripping efficiency and the utilization rate of the ingot portion.
Smart Images
Figure CN224124547U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor material preparation, and in particular to a stripping device for silicon carbide wafers. Background Technology
[0002] Silicon carbide (SiC), as a core material for third-generation semiconductors, possesses a wide bandgap (3.26 eV) and high thermal conductivity (4.9 W / cm·K), effectively reducing heat accumulation during power device operation. Furthermore, SiC exhibits an electron saturation drift velocity as high as 2 × 10⁻⁶. 7 With a speed of cm / s, SiC can be widely used in high-frequency devices. It is one of the most important third-generation semiconductor materials in fields such as electric vehicles, photovoltaics, and radio frequency communications.
[0003] To obtain silicon carbide wafers, laser stealth cutting of silicon carbide ingots can be used. For example, patent CN119017568A uses ultrasonic waves to act on an ultrasonic liquid medium. Through ultrasonic resonance, the laser-cut silicon carbide wafers are peeled off from the silicon carbide ingots. However, there is a problem: after the silicon carbide wafers are detached from the silicon carbide ingots under the action of ultrasonic waves, they will move randomly in the ultrasonic liquid medium. This can easily cause the silicon carbide wafers to collide with the inner wall of the container containing the ultrasonic liquid medium, resulting in extremely small scratches, chipping, and breakage of the silicon carbide wafers, which affects the quality and yield of the products.
[0004] This utility model solves at least one of the above problems. Utility Model Content
[0005] In order to solve the problem that in the prior art, after silicon carbide wafers are detached from silicon carbide ingots under ultrasonic action, they move randomly in the ultrasonic liquid medium, which easily leads to collisions between the silicon carbide wafers and the inner wall of the container containing the ultrasonic liquid medium, causing the silicon carbide wafers to have minute scratches, chipping, and breakage, affecting product quality and yield, the purpose of this utility model is to provide a silicon carbide wafer stripping device.
[0006] To achieve the above objectives, this utility model provides the following technical solution:
[0007] A first aspect of this utility model provides a silicon carbide wafer stripping device, comprising:
[0008] A container tank used to hold liquid media;
[0009] A clamping and lifting device is used to clamp and fix the first silicon carbide crystal ingot and to drive the first silicon carbide crystal ingot to be immersed in the liquid medium in the receiving tank; the first silicon carbide crystal ingot includes a crystal ingot portion, a modified layer and a wafer portion stacked sequentially along its thickness direction;
[0010] An ultrasonic device includes an ultrasonic transducer disposed on the outside of the bottom of the receiving tank, for resonating the liquid medium in the receiving tank with the first silicon carbide ingot, so as to separate the ingot portion and the wafer portion of the first silicon carbide ingot to obtain a first silicon carbide wafer; wherein, the first silicon carbide wafer is the separated wafer portion.
[0011] A magnetic attraction device is disposed on the inner side of the bottom of the receiving groove. The magnetic attraction device has a first magnetic attraction surface and is used to magnetically attract the first silicon carbide wafer during the separation of the wafer part and the ingot part, so as to adsorb and fix the first silicon carbide wafer.
[0012] In some possible implementations, the first silicon carbide ingot is a ferromagnetic silicon carbide crystal;
[0013] Alternatively, the first silicon carbide ingot is a non-ferromagnetic silicon carbide crystal, and a magnetic material layer is attached to the lower surface of the wafer portion; wherein the magnetic material layer has a first adhesive surface and an adsorption surface opposite to each other along its thickness direction, and the first adhesive surface is bonded to the lower surface of the wafer portion of the first silicon carbide ingot.
[0014] And / or, the diameter of the magnetic attraction device is smaller than the diameter of the first silicon carbide ingot.
[0015] In some possible implementations, the ultrasonic device further includes a generator body configured to sequentially generate a first ultrasonic signal and a second ultrasonic signal.
[0016] The ultrasonic transducer is disposed at the output end of the generator body and is configured sequentially as follows:
[0017] It is used to receive the first ultrasonic signal and vibrate at a first preset vibration frequency to resonate the liquid medium and the first silicon carbide ingot.
[0018] After receiving the second ultrasonic signal, it vibrates at a second preset vibration frequency to resonate with the liquid medium and the first silicon carbide ingot, so that the ingot part and the wafer part of the first silicon carbide ingot are separated to obtain the second silicon carbide ingot and the first silicon carbide wafer.
[0019] Wherein, the first preset vibration frequency is less than the second preset vibration frequency.
[0020] In some possible implementations, the stripping apparatus further includes a grinding device for thinning grinding of the second silicon carbide ingot and / or the first silicon carbide wafer;
[0021] The surface in contact between the first silicon carbide wafer and the second silicon carbide ingot is a first damaged layer. The grinding device performs a thinning grinding process on the first damaged layer of the first silicon carbide wafer to remove the first damaged layer and obtain the second silicon carbide wafer. The thickness of the first damaged layer is 20-50 μm.
[0022] And / or, the surface of the second silicon carbide ingot that contacts the first silicon carbide wafer is a second damaged layer, and the grinding device performs a thinning grinding process on the second damaged layer of the second silicon carbide ingot to remove the second damaged layer and obtain a third silicon carbide ingot; wherein, the thickness of the second damaged layer is 20 to 50 μm.
[0023] In some possible implementations, the distance between the first magnetic attraction surface and the lower surface of the wafer portion is 5 to 30 mm, or the distance between the first magnetic attraction surface and the adsorption surface of the magnetic material layer is 5 to 30 mm.
[0024] And / or, the cross-sectional area of the first magnetic attraction surface is smaller than the cross-sectional area of the wafer portion.
[0025] In some possible implementations, the magnetic suction device is an electromagnetic chuck, which is configured to adjust the magnetic force of the electromagnetic chuck according to the thickness of the first silicon carbide wafer, wherein the thickness of the first silicon carbide wafer is 0.2 to 1 mm, and the magnetic force is 4.05 × 10⁻⁵ volts / meter to 1.46 × 10⁻³ volts / meter.
[0026] In some possible implementations, the magnetic attraction device further has a second magnetic attraction surface that is opposite to the first magnetic attraction surface along the thickness direction, and the second magnetic attraction surface is attracted to the inner side of the bottom of the receiving groove.
[0027] In some possible implementations, the magnetic attraction device further includes at least one groove formed by the first magnetic attraction surface being recessed along the thickness direction of the magnetic attraction device.
[0028] In some possible implementations, a buffer layer is provided on the first magnetic surface of the magnetic attraction device. The buffer layer has an elastic surface and a second adhesive surface opposite each other along the thickness direction. The second adhesive surface and the first magnetic surface are connected. The cross-sectional area of the buffer layer is smaller than the cross-sectional area of the first silicon carbide wafer.
[0029] In some possible implementations, the stripping device further includes:
[0030] A laser emitter is used to emit a laser beam that irradiates the upper surface of an initial silicon carbide ingot, so as to form the modified layer inside the initial silicon carbide ingot, thereby obtaining the first silicon carbide ingot; wherein, the modified layer divides the first silicon carbide ingot into an ingot portion and a wafer portion along the thickness direction of the first silicon carbide ingot.
[0031] A focusing objective lens is disposed between the laser emitter and the initial silicon carbide ingot to focus the laser emitted by the laser emitter onto the initial silicon carbide ingot.
[0032] Compared with the prior art, the beneficial effects of this utility model are as follows: a modified layer is formed inside the first silicon carbide crystal ingot. Under the action of the ultrasonic waves emitted by the ultrasonic device, the liquid medium resonates with the first silicon carbide crystal ingot and acts on the modified layer, causing the wafer part and the ingot part of the first silicon carbide crystal ingot to separate. The wafer part is peeled off from the first silicon carbide crystal ingot to obtain the first silicon carbide wafer. During the separation process of the wafer part and the ingot part, the first magnetic surface of the magnetic attraction device is used to magnetically attract the first silicon carbide wafer to adsorb and fix the first silicon carbide wafer.
[0033] On the one hand, by combining the resonance of the ultrasonic device and the adsorption of the magnetic device, the first silicon carbide wafer can be quickly separated from the first silicon carbide ingot.
[0034] On the other hand, the magnetic force generated by the magnetic attraction device guides the first silicon carbide wafer after it has been detached to move slowly toward the magnetic attraction device until it is fixed on the magnetic attraction device. During this process, the direction and trajectory of the first silicon carbide wafer are limited, so that it will not collide with the inside of the receiving groove during the movement. This avoids the occurrence of scratches, chipping or breakage caused by the irregular movement of the first silicon carbide wafer during ultrasonic peeling, ensuring the product quality and yield of the first silicon carbide wafer, and making it convenient to directly enter the subsequent substrate processing process of the first silicon carbide wafer to obtain a qualified silicon carbide substrate.
[0035] Thirdly, due to the resonance effect generated by ultrasound, the cracks in the modified layer extend along the vertical direction (that is, the thickness direction of the first silicon carbide ingot). The ingot part and the wafer part of the first silicon carbide ingot will slowly peel off. During this process, the magnetic force generated by the magnetic attraction device will perform adsorption-type assisted peeling of the wafer part, which will strengthen the guidance and control of the crack propagation path and reduce the random deviation of transverse cracks. This not only reduces the cutting loss thickness and improves the utilization rate of the ingot part, but also improves the peeling efficiency, reduces the roughness of the separation surface, and further avoids the generation of microcracks and edge chipping in the first silicon carbide wafer. Attached Figure Description
[0036] Figure 1This invention provides a silicon carbide wafer stripping device and a structural schematic diagram of a first silicon carbide ingot.
[0037] In the figure: 1. Ultrasonic device; 10. Generator body; 11. Ultrasonic transducer; 2. Magnetic suction device; 3. Lifting and clamping device; 4. Receiving tank; 5. Liquid medium; 6. First photoelectric sensor; 7. Second photoelectric sensor; 100. First silicon carbide ingot; 101. Wafer portion; 102. Modified layer; 103. Ingot portion. Detailed Implementation
[0038] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.
[0039] The terms used to describe position and direction in this utility model are illustrated with the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this utility model.
[0040] Please see Figure 1 This embodiment provides a silicon carbide wafer stripping device, which includes an ultrasonic device 1, a magnetic suction device 2, a clamping and lifting device 3, and a receiving groove 4.
[0041] The container tank 4 is used to contain the liquid medium 5. The tank body material of the container tank 4 can be either martensitic stainless steel 410 / 420 / 430 series or ferritic stainless steel 410 / 420 / 430 series. Martensitic stainless steel, due to its high chromium and iron content, has a predominantly martensitic crystal structure and exhibits significant magnetism, thus it can be attracted by a magnet; ferritic stainless steel also has a predominantly ferrite crystal structure and exhibits significant magnetism, thus it can also be attracted by a magnet. The liquid medium 5 can be water, oil, emulsion, etc.
[0042] Because ultrasound generates strong cavitation in water, producing bubbles, the bursting of these bubbles exerts shear and tensile forces on the cracks in the modified layer 102, promoting crack propagation. Therefore, water is the preferred liquid medium 5.
[0043] In some embodiments, at least a portion of the sidewalls of the receiving groove 4 are made of a transparent material, which facilitates manual observation of the separation status of the ingot portion 103 and the wafer portion 101, and makes it easier to calculate the single-wafer peeling time.
[0044] It should be noted that the single-piece peeling time refers to the time difference between the start of the ultrasonic device 1 and the turn off of the ultrasonic device 1; that is, when the ultrasonic device 1 is started, the first silicon carbide ingot 100 begins to peel, and when a clear gap is seen between the wafer part 101 and the ingot part 103, and physical separation is achieved, the ultrasonic device 1 is turned off, and the peeling ends.
[0045] In a preferred embodiment, the inner sidewall of the receiving groove 4 is provided with a first photoelectric sensor (emitting type) 6 and a second photoelectric sensor (receiving type) 7 that are opposite to each other and maintained at the same height (the height position is located between the upper and lower surfaces of the first silicon carbide ingot 100). When not peeled off, the second photoelectric sensor 7 cannot receive the photoelectric signal emitted by the first photoelectric sensor 6 due to the obstruction of the first silicon carbide ingot 100. When the peeling is completed, due to the rupture of the modified layer 102, the ingot part 103 and the wafer part 101 separate, and a gap appears between them. The second photoelectric sensor 7 can receive the photoelectric signal emitted by the first photoelectric sensor 6 through the gap.
[0046] Furthermore, by sending the received photoelectric signal from the second photoelectric sensor 7 to the ultrasonic device 1, the ultrasonic device 1 is turned off. This implementation not only allows for more accurate calculation of the single-piece peeling time but also enables automated control of the ultrasonic device 1, reducing delays and errors caused by manual processing.
[0047] The clamping and lifting device 3 is used to clamp and fix the first silicon carbide ingot 100, and can immerse the first silicon carbide ingot 100 in the liquid medium 5 in the receiving tank 4. In practical applications, the clamping and lifting device 3 is located near the receiving tank 4, and can clamp and fix the first silicon carbide ingot 100 through the clamp, and can drive the first silicon carbide ingot 100 to move up and down, so that the first silicon carbide ingot 100 can be immersed in the liquid medium 5 in the receiving tank 4. The specific structure of the clamping and lifting device 3 is a conventional technical means, and will not be described in detail here.
[0048] like Figure 1 As shown, the first silicon carbide ingot 100 includes an ingot portion 103, a modified layer 102, and a wafer portion 101 stacked sequentially along its thickness direction.
[0049] Furthermore, the first silicon carbide ingot 100 is a ferromagnetic silicon carbide crystal, such as a silicon carbide crystal doped with iron, cobalt, or nickel, and its wafer portion 101 can be magnetically fixed by the magnetic attraction device 2. Alternatively, the first silicon carbide ingot 100 is a non-ferromagnetic silicon carbide crystal, such as a pure silicon carbide crystal, and a magnetic material layer is attached to the lower surface of the wafer portion 101; wherein the magnetic material layer has a first adhesive surface and an adsorption surface opposite to each other along its thickness direction, and the first adhesive surface is bonded to the lower surface of the wafer portion 101 of the first silicon carbide ingot 100 so that the adsorption surface of the magnetic material layer can be magnetically fixed by the magnetic attraction device 2.
[0050] Silicon carbide crystals doped with cobalt, iron, or nickel exhibit ferromagnetism, and their physical properties are significantly enhanced, primarily in terms of improved mechanical and microwave absorption properties. Specifically, cobalt-, iron-, and nickel-doped silicon carbide materials show increased dielectric and magnetic relaxation peaks, thereby improving their microwave absorption performance. Cobalt-, iron-, and nickel-doped silicon carbide has potential applications in fields such as magnetic storage devices, leading to widespread research interest in its magnetorheological and piezoelectric properties.
[0051] The ultrasonic device 1 includes an ultrasonic transducer 11, which is disposed on the outside of the bottom of the accommodating tank 4. The ultrasonic transducer 11 is used to make the liquid medium 5 in the accommodating tank 4 resonate with the first silicon carbide ingot 100, so as to separate the ingot portion 103 and the wafer portion 101 of the first silicon carbide ingot 100 to obtain the first silicon carbide wafer.
[0052] It should be noted that the first silicon carbide wafer includes at least the separated wafer portion 101.
[0053] The magnetic attraction device 2 is disposed on the inner side of the bottom of the receiving groove 4. The magnetic attraction device 2 has a first magnetic attraction surface, which is used to magnetically attract the first silicon carbide wafer during the separation process of the wafer part 101 and the ingot part 103, so as to adsorb and fix the first silicon carbide wafer.
[0054] It should be noted that the ferromagnetic silicon carbide crystal or magnetic material layer has the same magnetism as the bottom of the receiving tank 4, and the magnetism is opposite to that of the first magnetic surface of the magnetic attraction device 2.
[0055] The working process of the stripping device is as follows: the ultrasonic device 1 is started. Under the action of the ultrasonic waves generated by the ultrasonic device 1, the ultrasonic transducer 11 causes the liquid medium 5 to resonate with the first silicon carbide ingot 100, so that the wafer part 101 is separated from the first silicon carbide ingot 100 to obtain the first silicon carbide wafer.
[0056] Because the first silicon carbide wafer, after detachment, will undergo random free movement in the liquid medium 5, it will collide with the inner wall of the container tank 4 containing the liquid medium 5, causing minute scratches, chipping, and breakage to the first silicon carbide wafer, thus affecting the product quality and yield of the first silicon carbide wafer. Based on this, during the phase separation process of the wafer portion 101 and the ingot portion 103, the first magnetic attraction surface of the magnetic attraction device 2 is used to magnetically attract the first silicon carbide wafer to adsorb and fix it.
[0057] On the one hand, by combining the resonance of the ultrasonic device 1 and the adsorption of the magnetic attraction device 2, the first silicon carbide crystal ingot 100 can be quickly peeled off from the first silicon carbide crystal ingot 100.
[0058] On the other hand, the magnetic force generated by the magnetic attraction device 2 causes the first silicon carbide wafer, after being detached, to slowly move towards the magnetic attraction device 2 under the guidance of the magnetic force until it is attracted and fixed on the magnetic attraction device 2. During this process, the movement direction and trajectory of the first silicon carbide wafer are limited, so that it will not collide with the inside of the receiving groove 4 during the movement. This avoids the occurrence of scratches, chipping, or breakage caused by the irregular movement of the first silicon carbide wafer during ultrasonic peeling, ensuring the product quality and yield of the first silicon carbide wafer, and facilitating its direct entry into the subsequent substrate processing process of the first silicon carbide wafer to obtain a qualified silicon carbide substrate.
[0059] Thirdly, due to the resonance effect generated by ultrasound, the cracks in the modified layer 102 extend along the vertical direction (that is, the thickness direction of the first silicon carbide ingot 100), and the ingot portion 103 and the wafer portion 101 of the first silicon carbide ingot 100 will slowly peel off. During this process, the magnetic force generated by the magnetic attraction device 2 performs adsorption-type assisted peeling of the wafer portion 101, strengthens the guidance and control of the crack propagation path, reduces the random deviation of transverse cracks, not only reduces the cutting loss thickness and improves the utilization rate of the ingot portion 103, but also improves the peeling efficiency, reduces the roughness of the separation surface, and further avoids the generation of microcracks and edge chipping in the first silicon carbide wafer.
[0060] In one specific embodiment, the stripping device further includes a laser emitter (not shown) and a focusing objective (not shown).
[0061] A laser emitter is used to emit a laser that irradiates the upper surface of the initial silicon carbide ingot, so that a modified layer 102 is formed inside the initial silicon carbide ingot, resulting in a first silicon carbide ingot 100; wherein, the modified layer 102 divides the first silicon carbide ingot 100 into an ingot portion 103 and a wafer portion 101 along the thickness direction of the first silicon carbide ingot 100.
[0062] The focusing objective is positioned between the laser emitter and the initial silicon carbide ingot to focus the laser emitted from the laser emitter onto the initial silicon carbide ingot.
[0063] Initial silicon carbide ingots include, but are not limited to, industrial-grade, research-grade, and test-grade quality ingots. Furthermore, the crystal forms of initial silicon carbide ingots include, but are not limited to, 4H-SiC, 6H-SiC, or 3C-SiC.
[0064] Furthermore, the initial silicon carbide ingot has a thickness of 15–50 mm, for example, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm, 28 mm, 30 mm, 32 mm, 35 mm, 38 mm, 40 mm, 42 mm, 45 mm, 48 mm, or 50 mm; the initial silicon carbide ingot has a diameter of 2–12 inches, for example, 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 7 inches, 8 inches, 9 inches, 10 inches, 11 inches, or 12 inches. In application, the surface of the initial silicon carbide ingot is thinned and ground using an 8000#–10000# diamond wheel to achieve a surface roughness of less than 5 nm for the first silicon carbide ingot 100.
[0065] It is worth noting that the principle of laser stealth cutting is to use a laser emitter to generate a high-energy-density laser to irradiate the initial silicon carbide ingot and penetrate through the surface of the initial silicon carbide ingot. The laser is focused at a certain depth inside the initial silicon carbide ingot and scans back and forth, forming a local high-temperature environment inside the initial silicon carbide ingot. This causes changes in the internal structure of the material (such as local microcracks, dislocations, and partial recrystallization), thereby producing a modified layer 102 inside the initial silicon carbide ingot. Laser stealth cutting of initial silicon carbide ingots is a non-contact cutting method. Because non-contact cutting does not generate mechanical stress, thermal stress, or material debris, it is very suitable for cutting and slicing initial silicon carbide ingots, and can obtain ultra-thin silicon carbide wafers and silicon carbide seed crystals.
[0066] For example, the wavelength of the laser is 355–1080 nm, such as 355 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, or 1080 nm; and / or, the pulse width of the laser is 500 ps–2 ns, such as 500 ps, 550 ps, 600 ps, 650 ps, 700 ps, 750 ps, 800 ps, 850 ps, 900 ps, 950 ps, 1 ns, 1.5 ns, or 2 ns. ; and / or, the repetition frequency of the laser irradiation is 100 to 1000 kHz, for example, it can be 100 kHz, 150 kHz, 200 kHz, 250 kHz, 300 kHz, 350 kHz, 400 kHz, 450 kHz, 500 kHz, 550 kHz, 600 kHz, 650 kHz, 700 kHz, 750 kHz, 800 kHz, 850 kHz, 900 kHz, 950 kHz or 1000 kHz; and / or, the power of the laser is 20 to 60 W, for example, it can be 20 W, 25 W, 30 W, 35 W, 40 W, 45 W, 50 W, 55 W or 60 W.
[0067] It should be further explained that the cross-sectional area of the modified layer 102 is the same as that of the first silicon carbide ingot 100, and the modified layer 102 divides the first silicon carbide ingot 100 into an ingot portion 103 and a wafer portion 101 along the thickness direction of the second silicon carbide ingot.
[0068] In one specific embodiment, the ultrasonic device 1 further includes a generator body 10, which is configured to generate a first ultrasonic signal and a second ultrasonic signal sequentially.
[0069] The ultrasonic transducer 11 is located at the output end of the generator body 10 and is configured sequentially as follows:
[0070] It is used to receive the first ultrasonic signal and vibrate at the first preset vibration frequency to resonate the liquid medium 5 and the first silicon carbide ingot 100.
[0071] After receiving the second ultrasonic signal, it vibrates at the second preset vibration frequency to resonate with the liquid medium 5 and the first silicon carbide ingot 100, so that the ingot portion 103 and the wafer portion 101 of the first silicon carbide ingot 100 are separated to obtain the second silicon carbide ingot and the first silicon carbide wafer.
[0072] It should be noted that the first preset vibration frequency is less than the second preset vibration frequency.
[0073] A first ultrasonic wave is generated at a low-frequency first ultrasonic frequency, causing the liquid medium 5 and the first silicon carbide ingot 100 to resonate. This low-frequency resonance eliminates cracks within the modified layer 102, connecting all discontinuous sub-modified layers into a unified structure. Then, a second ultrasonic wave is generated at a high-frequency second ultrasonic frequency, also causing resonance between the liquid medium 5 and the first silicon carbide ingot 100. Since the cracks within the modified layer 120 have been eliminated, forming a unified structure, the ingot portion 103 and the wafer portion 101 of the first silicon carbide ingot 100 can physically separate along both ends of the unified structure under the high-frequency resonance of the second ultrasonic wave. This prevents the wafer portion 101 from fracturing due to the presence of the modified layer during resonance, further ensuring the product quality and yield of the first silicon carbide wafer while also reducing peeling time and improving peeling efficiency.
[0074] In existing technologies, a high-frequency ultrasonic generator and a low-frequency ultrasonic generator are typically placed at opposite ends of the receiving groove 4. The high-frequency ultrasonic generator is positioned above the first silicon carbide ingot 100, and the low-frequency ultrasonic generator is positioned below the first silicon carbide ingot 100, with the first silicon carbide ingot 100 resting on the low-frequency ultrasonic generator. Then, the first silicon carbide wafer is peeled off from the first silicon carbide ingot 100 by simultaneously applying high- and low-frequency ultrasonic waves to the modified layer 102. This method is prone to causing the first silicon carbide wafer to crack because when two ultrasonic waves of different frequencies act on the first silicon carbide ingot 100 simultaneously, the ultrasonic waves of different frequencies will produce complex interference inside the first silicon carbide ingot 100.
[0075] During the process of forming the modified layer 102 by laser stealth cutting, since the high-energy laser of laser stealth cutting is output in a pulsed manner rather than a continuous laser output, there are micro-cracks in the modified layer 102, which will form multiple discontinuous sub-modified layers. Therefore, this interference will produce local resonance enhancement and local resonance weakening unevenness for the modified layer after laser stealth cutting. This causes some sub-modified layers in the resonance enhancement area to detach from the modified layer 102 first, while other sub-modified layers in the resonance weakening area cannot detach from the modified layer 102. As a result, the first silicon carbide wafer will break under long-term high and low frequency resonance.
[0076] This embodiment peels off the first silicon carbide ingot 100 by using a low-frequency followed by a high-frequency resonance method, which avoids the situation where the wafer part 101 is broken due to the high and low frequency synergistic resonance, and further ensures the product quality and yield of the first silicon carbide wafer.
[0077] It should be noted that the higher the stripping efficiency, the less vibration the first silicon carbide wafer experiences, and the smaller the mechanical stress generated by the vibration. This is beneficial for subsequent fine grinding and polishing of the first silicon carbide wafer, further improving product quality.
[0078] For example, for ultrasonic device 1, the frequency range of the ultrasonic waves it generates can be 20KHz to 80KHz; the first preset vibration frequency can be 20 to 40KHz, for example, 20KHz, 22KHz, 25KHz, 28KHz, 30KHz, 32KHz, 35KHz, 38KHz or 40KHz; the second preset vibration frequency can be 40 to 80KHz, for example, 40KHz, 45KHz, 50KHz, 55KHz, 60KHz, 65KHz, 70KHz, 75KHz or 80KHz.
[0079] Preferably, the ultrasonic device 1 can be configured as a 20 / 50KHz dual-frequency ultrasonic generator, with a first preset vibration frequency of 20KHz and a second preset vibration frequency of 50KHz; or, the ultrasonic device 1 can be configured as a 28 / 40KHz dual-frequency ultrasonic generator, with a first preset vibration frequency of 28KHz and a second preset vibration frequency of 40KHz; or, the ultrasonic device 1 can be configured as a 40 / 80KHz dual-frequency ultrasonic generator, with a first preset vibration frequency of 40KHz and a second preset vibration frequency of 80KHz.
[0080] For example, the amplitude of the ultrasound is 3 to 10 μm, such as 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm; the power of the ultrasound is 100 to 300 W, such as 100 W, 150 W, 200 W, 250 W or 300 W.
[0081] In one specific embodiment, the stripping apparatus further includes a grinding device (not shown) for thinning grinding of the second silicon carbide ingot and / or the first silicon carbide wafer.
[0082] The surface in contact between the first silicon carbide wafer and the second silicon carbide ingot is a first damaged layer. The first damaged layer of the first silicon carbide wafer is thinned by a grinding device to remove the first damaged layer and obtain the second silicon carbide wafer. The thickness of the first damaged layer is 20 to 50 μm, for example, it can be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm.
[0083] After the ingot portion 103 and the wafer portion 101 of the first silicon carbide ingot 100 are separated, the surface of the first silicon carbide wafer that contacts the second silicon carbide ingot has peel damage. In order to improve the flatness of the first silicon carbide wafer, it is necessary to enter the polishing production stage. The first damaged layer is removed by thinning and grinding to form a qualified silicon carbide substrate product, namely the second silicon carbide wafer.
[0084] The surface of the second silicon carbide ingot that contacts the first silicon carbide wafer is a second damaged layer. The second damaged layer of the second silicon carbide ingot is thinned by a grinding device to remove the second damaged layer and obtain a third silicon carbide ingot. The thickness of the second damaged layer is 20 to 50 μm, for example, it can be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm.
[0085] After the ingot portion 103 and the wafer portion 101 of the first silicon carbide ingot 100 are separated, the surface of the second silicon carbide ingot that contacts the first silicon carbide wafer has peeling damage. In order to improve the flatness of the second silicon carbide ingot, it needs to enter the polishing production stage. The second damaged layer is removed by thinning grinding to form a qualified silicon carbide ingot to be peeled, namely the third silicon carbide ingot.
[0086] In some specific embodiments, the diameter of the magnetic suction device 2 is smaller than the diameter of the first silicon carbide wafer; for example, the diameter of the magnetic suction device 2 is 50% to 90% of the diameter of the first silicon carbide wafer, which makes it easier for a person or a robot to remove the first silicon carbide wafer adsorbed from the magnetic suction device 2.
[0087] In some specific embodiments, the distance between the first magnetic attraction surface and the lower surface of the wafer portion 101 is 5 to 30 mm; or the distance between the first magnetic attraction surface and the adsorption surface of the magnetic material layer is 5 to 30 mm.
[0088] Before the ultrasonic transducer 11 causes the liquid medium 5 in the accommodating tank 4 and the first silicon carbide ingot 100 to resonate, the clamping lifting device 3 adjusts the position of the first silicon carbide ingot 100 in the liquid medium 5 so that the distance between the lower surface of the wafer portion 101 of the first silicon carbide ingot 100 and the first magnetic attraction surface, i.e., the vertical distance, is 5 to 30 mm, for example, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, or 30 mm. Alternatively, the distance between the first adsorption surface of the magnetic material layer and the first magnetic attraction surface, i.e., the vertical distance, is 5 to 30 mm, for example, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, or 30 mm.
[0089] Within this vertical distance range, it can not only ensure that the first silicon carbide wafer is attracted by the first magnetic surface within the magnetic force range of the magnetic attraction device 2, but also ensure that its movement direction and trajectory will not deviate from the vertical direction towards the first magnetic surface under the guidance of the magnetic force, thus avoiding collision between the first silicon carbide wafer and the receiving groove 4.
[0090] In some specific embodiments, the cross-sectional area of the first magnetic surface is smaller than the cross-sectional area of the wafer portion 101. The purpose of this embodiment is to facilitate the separation of the first silicon carbide wafer from the first magnetic surface after the first silicon carbide wafer is attracted and fixed by the first magnetic surface of the magnetic device 2.
[0091] In some specific embodiments, the magnetic suction device 2 is an electromagnetic chuck, which is configured to adjust the magnetic force of the electromagnetic chuck according to the thickness of the first silicon carbide wafer. Preferably, the thickness of the first silicon carbide wafer is 0.2–1 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm; the magnetic force is 4.05 × 10⁻⁵ volts / meter to 1.46 × 10⁻³ volts / meter, for example, 5 × 10⁻⁵ volts / meter. -5 Volts / meter, 20 × 10 -5 Volts / meter, 35 × 10 -5 Volts / meter, 50 × 10 -5 Volts / meter, 65 × 10 -5 Volts / meter, 80 × 10 -5 Volts / meter, 95 × 10 -5 Volts / meter, 110 × 10 -5 Volts / meter or 146 × 10 -5 Volts per meter.
[0092] In some specific embodiments, the magnetic attraction device 2 further has a second magnetic attraction surface that is opposite to the first magnetic attraction surface along the thickness direction, and the second magnetic attraction surface is adsorbed onto the bottom of the receiving groove 4. The purpose of this embodiment is to keep the magnetic attraction device 2 and the receiving groove 4 fixed under the action of magnetic force, ensuring that the first silicon carbide wafer can be stably adsorbed on the first magnetic attraction surface of the magnetic attraction device 2, and preventing the first silicon carbide wafer from colliding with the receiving groove 4.
[0093] In some specific embodiments, the magnetic attraction device 2 further includes at least one groove, which is formed by recessing the first magnetic attraction surface along the thickness direction of the magnetic attraction device 2. The purpose of this embodiment is that after the first silicon carbide wafer is attracted and fixed by the first magnetic attraction surface of the magnetic attraction device 2, the presence of the groove facilitates the separation of the first silicon carbide wafer from the first magnetic attraction surface.
[0094] In some specific embodiments, a buffer layer is provided on the second magnetic surface of the magnetic attraction device 2, and the cross-sectional area of the buffer layer is smaller than the cross-sectional area of the first silicon carbide wafer.
[0095] The buffer layer has an elastic surface and a second adhesive surface along its thickness direction. The second adhesive surface is bonded to the first magnetic surface. When the first silicon carbide wafer is attracted and fixed by the magnetic attraction device 2, the first silicon carbide wafer comes into contact with the elastic surface of the buffer layer. This is to buffer the micro-impact of the first silicon carbide wafer under the action of magnetic force, avoid defects caused by direct contact and collision between the first silicon carbide wafer and the second magnetic surface, and further improve the product quality and yield of the first silicon carbide wafer. At the same time, the cross-sectional area of the buffer layer is smaller than the cross-sectional area of the first silicon carbide wafer, which allows the first silicon carbide wafer to get rid of the magnetic force of the second magnetic surface smoothly, thereby achieving separation from the buffer layer.
[0096] Compared with the current traditional wire-cut silicon carbide ingots, the peeling device of this utility model is a purely physical slicing device that completely peels the wafer portion off the first silicon carbide ingot after it has been cut by high-energy short-pulse laser stealth cutting with iron, cobalt or nickel.
[0097] The peeling device of this invention uses a laser emitter to perform laser stealth cutting inside the initial silicon carbide ingot to generate a specific modified layer and obtain the first silicon carbide ingot; then, it uses the resonance principle of the ultrasonic device and the adsorption principle of the magnetic device to physically peel the wafer part and the ingot part after laser stealth cutting. The peeling speed of this device is relatively fast.
[0098] Furthermore, taking advantage of the ferromagnetic properties of silicon carbide ingots, which allow them to be attracted by magnets, a magnetic adsorption device is used under ultrasonic waves to adsorb and peel the laser-cut wafer portion from the first silicon carbide ingot and fix it on the magnetic adsorption device. This avoids the irregular movement of the first silicon carbide wafer during ultrasonic peeling, which could cause chipping or breakage. The peeled wafer is intact, with no chipping or breakage at the edges, and can then proceed to the normal substrate processing steps to produce qualified silicon carbide substrate products.
[0099] Furthermore, the second silicon carbide ingot after being peeled off is intact, and the surface of the third silicon carbide ingot after thinning and grinding has a high degree of smoothness, which can be used for laser stealth cutting to form a new first silicon carbide ingot to be peeled off. This process is repeated layer by layer until the ingot is completely peeled off into wafers, which can ultimately achieve high-efficiency and low-cost cutting of silicon carbide ingots and can quickly peel off the wafer part from the ingot part of each first silicon carbide ingot.
[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention, and all such changes should fall within the protection scope of the claims of the present invention.
Claims
1. A silicon carbide wafer stripping device, characterized in that, include: A container tank used to hold liquid media; A clamping and lifting device is used to clamp and fix a first silicon carbide crystal ingot and to immerse the first silicon carbide crystal ingot in the liquid medium; the first silicon carbide crystal ingot includes an ingot portion, a modified layer and a wafer portion stacked sequentially along its thickness direction; An ultrasonic device includes an ultrasonic transducer disposed on the outside of the bottom of the receiving groove, for resonating the liquid medium in the receiving groove with the first silicon carbide ingot, so as to separate the ingot portion and the wafer portion of the first silicon carbide ingot to obtain a first silicon carbide wafer; wherein the first silicon carbide wafer includes at least the separated wafer portion. A magnetic attraction device is disposed on the inner side of the bottom of the receiving groove. The magnetic attraction device has a first magnetic attraction surface and is used to magnetically attract the first silicon carbide wafer during the separation of the wafer part and the ingot part, so as to adsorb and fix the first silicon carbide wafer.
2. The stripping device according to claim 1, characterized in that, The first silicon carbide ingot is a ferromagnetic silicon carbide crystal; or, the first silicon carbide ingot is a non-ferromagnetic silicon carbide crystal, and a magnetic material layer is attached to the lower surface of the wafer portion; wherein, the magnetic material layer has a first adhesive surface and an adsorption surface opposite to each other along its thickness direction, and the first adhesive surface is bonded to the lower surface of the wafer portion of the first silicon carbide ingot. And / or, the diameter of the magnetic attraction device is smaller than the diameter of the first silicon carbide ingot.
3. The stripping device according to claim 1 or 2, characterized in that, The ultrasonic device also includes a generator body, which is configured to generate a first ultrasonic signal and a second ultrasonic signal sequentially. The ultrasonic transducer is disposed at the output end of the generator body and is configured sequentially as follows: It is used to receive the first ultrasonic signal and vibrate at a first preset vibration frequency to resonate the liquid medium and the first silicon carbide ingot. After receiving the second ultrasonic signal, it vibrates at a second preset vibration frequency to resonate with the liquid medium and the first silicon carbide ingot, so that the ingot part and the wafer part of the first silicon carbide ingot are separated to obtain the second silicon carbide ingot and the first silicon carbide wafer. Wherein, the first preset vibration frequency is less than the second preset vibration frequency.
4. The peeling device according to claim 3, characterized in that, It also includes a grinding apparatus for thinning grinding of the second silicon carbide ingot and / or the first silicon carbide wafer; The surface in contact between the first silicon carbide wafer and the second silicon carbide ingot is a first damaged layer. The grinding device performs a thinning grinding process on the first damaged layer of the first silicon carbide wafer to remove the first damaged layer and obtain the second silicon carbide wafer. The thickness of the first damaged layer is 20-50 μm. And / or, the surface of the second silicon carbide ingot that contacts the first silicon carbide wafer is a second damaged layer, and the grinding device performs a thinning grinding process on the second damaged layer of the second silicon carbide ingot to remove the second damaged layer and obtain a third silicon carbide ingot; wherein, the thickness of the second damaged layer is 20 to 50 μm.
5. The stripping device according to claim 2, characterized in that, The distance between the first magnetic attraction surface and the lower surface of the wafer portion is 5 to 30 mm, or the distance between the first magnetic attraction surface and the adsorption surface of the magnetic material layer is 5 to 30 mm; And / or, the cross-sectional area of the first magnetic attraction surface is smaller than the cross-sectional area of the wafer portion.
6. The stripping device according to claim 1, characterized in that, The magnetic suction device also has a second magnetic suction surface that is opposite to the first magnetic suction surface along the thickness direction, and the second magnetic suction surface is adsorbed on the inner side of the bottom of the receiving groove.
7. The peeling device according to claim 1 or 6, characterized in that, The magnetic attraction device further includes at least one groove, which is formed by the first magnetic attraction surface being recessed along the thickness direction of the magnetic attraction device.
8. The stripping device according to claim 1 or 6, characterized in that, A buffer layer is provided on the first magnetic surface of the magnetic attraction device. The buffer layer has an elastic surface and a second adhesive surface that are opposite each other along the thickness direction. The second adhesive surface is in contact with the first magnetic surface. The cross-sectional area of the buffer layer is smaller than the cross-sectional area of the first silicon carbide wafer.
9. The stripping device according to claim 1, characterized in that, The stripping device further includes: A laser emitter is used to emit a laser beam that irradiates the upper surface of an initial silicon carbide ingot, so as to form the modified layer inside the initial silicon carbide ingot, thereby obtaining the first silicon carbide ingot; wherein, the modified layer divides the first silicon carbide ingot into an ingot portion and a wafer portion along the thickness direction of the first silicon carbide ingot. A focusing objective lens is disposed between the laser emitter and the initial silicon carbide ingot to focus the laser emitted by the laser emitter onto the initial silicon carbide ingot.
10. The stripping device according to claim 1, characterized in that, The magnetic suction device is an electromagnetic chuck, configured to adjust its magnetic force according to the thickness of the first silicon carbide wafer. The thickness of the first silicon carbide wafer is 0.2–1 mm, and the magnetic force is 4.05 × 10⁻⁶ mm. -5 Volts / meter ~ 1.46 × 10⁻⁶ -3 Volts per meter.