An ultrasonic assisted peeling device and method

Abstract

The application discloses an ultrasonic auxiliary peeling device, which comprises a tension and pressure fixing rod and an amplitude adjusting rod with two corresponding working surfaces, the two working surfaces are mutually parallel inclined surfaces and are respectively used for fixing two end surfaces of a to-be-peeled piece, an ultrasonic transducer is fixedly connected to the other end of the amplitude adjusting rod, a driving mechanism is used for driving the amplitude adjusting rod and the tension and pressure fixing rod to axially relatively move, and the tension and pressure fixing rod and the amplitude adjusting rod are coaxial or are arranged in parallel with the central axes. The application sets the oblique angle between the peeling surface and the peeling force direction, increases the peeling lateral force, simultaneously uses ultrasonic oscillation as an auxiliary, and separates the laser modified internal modification layer ingot or wafer with smaller force. The application can realize high-quality, fast, quick and simple wafer peeling mode for the laser processed ingot, and has wide application prospect in wafer processing of SiC, diamond and other new generation semiconductor materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wafer stripping technology, and particularly relates to a method for splitting a solid material into two parts. BACKGROUND

[0002] In the semiconductor industry, in order to separate wafers from a crystal ingot, a conventional wire cutting method is usually used to directly obtain wafers from the crystal ingot. For some solid materials with relatively high hardness and relatively high cost (such as SiC, diamond, etc.), the wire cutting not only has low production efficiency, but also causes great loss.

[0003] In order to improve the efficiency and reduce the loss, a laser processing method is used to first generate a modified layer inside the crystal ingot, and then separate the crystal ingot and the wafer. However, due to the limitation of the current laser process and the different solid materials to be separated, a large force is required for direct stripping. Y. Yamada et al. (Y. Yamada, T. Ikeda and J. Ikeno: Precision laser slicing technology for single crystal SiC wafer 1st report: Study on slicing method considering kerf-loss, J. Jpn. Soc. Abras. Technol., 64, 12 (2020) 635 (in Japanese). 10.11420 / jsat.64.635) mentioned that the force required for stripping a 1cm 2 square SiC wafer with a stripping scanning pitch of 20μm is 11.1MPa, i.e. 1110N, and the force required for stripping a SiC wafer with a stripping scanning pitch of 40μm is 25MPa, i.e. 2500N. If a 6-inch wafer is stripped under the condition of a stripping stress of this order of magnitude, an extremely large equipment will be required, and the surface shape of the wafer will inevitably be deteriorated, and in severe cases, the wafer will be cracked. It can be seen that the stripping technology is one of the key technologies for the industrialization of the current semiconductor material laser slicing technology.

[0004] In the patent document with the publication number CN 113714649 A and the title of a wafer manufacturing method, a wafer separation method is provided, which utilizes the thermal expansion and contraction of materials with different thermal expansion coefficients when the temperature changes to generate stress inside the wafer to promote wafer separation. However, when the solid colloidal material is heated to a liquid or molten state, the adhesive force of the adhesive layer will decrease and cannot be tightly bonded to the wafer. During the cooling process, the deformation of the colloidal thermal expansion and contraction, and the stress is difficult to be transmitted to the modified layer. Therefore, this method has poor stability, low success rate of wafer stripping after laser processing, too high requirements for temperature control and materials, and is difficult to realize engineering and productization.

[0005] The patent document with the publication number CN 111889896 A and the title of a crystal ingot peeling method assisted by ultrasonic and laser discloses a typical ultrasonic assisted peeling wafer method, which has the following defects: on the one hand, for the crystal ingot with a peeling thickness of 200-600 μm, the modified layer thickness is usually less than 50 μm, and it is difficult to achieve precise alignment when the ultrasonic tool head applies ultrasonic to the side surface of the crystal ingot. Without precise alignment, the ultrasonic force is applied to the non-modified layer part of the crystal ingot. When the modified layer is vibrated, the two parts of the wafer to be peeled and the crystal ingot are vibrated at the same time, the modified layer is not stressed, and it is difficult to form a crack propagation in the horizontal plane. On the other hand, the general crystal ingot has a cutting edge structure and is not a complete cylindrical shape. When the cutting edge moves to the inner arc surface of the ultrasonic tool head, this part cannot be attached to the ultrasonic tool head, and effective vibration cannot be formed, so this method is difficult to implement in actual equipment and cannot be applied to the wafer peeling process after laser processing.

[0006] The patent document with the publication number CN103579042A and the title of a system and method for separating bonded wafers provides a system for separating bonded wafers by applying a shearing force to the bonded wafers, but two sets of vacuum devices are needed to fix the upper and lower surfaces during the separation process, and two sets of servo motors and ball screws are used to twist the bonded upper and lower wafers in opposite directions, respectively. Therefore, the generation of shearing force needs expensive external mechanisms. For some wafers with relatively large bonding force, the suction cup fixing is easy to fall off, resulting in separation failure. In addition, due to the strong connection force inside the wafer after laser processing, a large torque is needed for twisting, which will result in a large equipment and damage to the wafer surface and increase the warping, and even cause the wafer to crack. Therefore, the simple shearing force separation cannot be applied to the separation of wafers after laser processing.

[0007] In view of the laser processed wafer peeling requirement, the current disclosed scheme cannot achieve high quality, fast, quick and simple effective peeling method, so a new scheme is urgently needed to solve this problem. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application provides a wafer peeling device and method based on ultrasonic assistance. Compared with the traditional simple application of pulling force or twisting separation, the peeling force required for the material to be peeled is smaller, and the peeling surface crack is more flat, and no crack is generated.

[0009] An ultrasonic assisted peeling device, comprising:

[0010] A tension and compression fixing rod and an amplitude adjusting rod have two corresponding working surfaces, which are mutually parallel inclined surfaces, respectively used for fixing two end surfaces of the wafer to be peeled;

[0011] ultrasonic transducer fixedly connected to the other end of the amplitude adjustment rod;

[0012] a driving mechanism for driving the amplitude adjustment rod and the tension-compression fixing rod to move axially relative to each other;

[0013] The tension-compression fixing rod and the amplitude adjustment rod are coaxial or have parallel central axes.

[0014] In the present application, the tension-compression fixing rod and the amplitude adjustment rod are each provided with an inclined working surface, and the two working surfaces are correspondingly arranged to fix the two end surfaces of the piece to be peeled. In actual installation, the two end surfaces of the piece to be peeled are first fixed to one end of the tension-compression fixing rod and the amplitude adjustment rod respectively, and then the tension-compression fixing rod is fixed, and then the ultrasonic transducer is connected to the other end of the amplitude adjustment rod; finally, the output end position of the driving mechanism is moved, and when it is moved to a proper position, the amplitude adjustment rod, the ultrasonic transducer and the output end of the driving mechanism (and the force sensor) are fixed.

[0015] The ultrasonic transducer is generally connected to another ultrasonic generator to convert electrical energy into ultrasonic mechanical energy, and the generated mechanical energy is transmitted along the amplitude adjustment rod to the piece to be peeled to assist peeling. The present application uses axially transmitted ultrasonic waves to avoid the problem that horizontal ultrasonic waves are difficult to align with the modified layer in the prior art.

[0016] The present application uses an inclined surface structure working surface to ensure that when an axial force is applied, two forces in different directions are generated on the modified layer of the piece to be peeled, one being a tensile stress perpendicular to the modified layer, and the other being a shear stress outward along the plane of the modified layer, without the need for an external device to provide a torsional force to achieve the same effect, and the system is simpler.

[0017] As a preferred embodiment, when the amplitude adjustment rod and the tension-compression fixing rod are vertically arranged, the included angle between the two working surfaces and the horizontal plane is 25°-50°. As a further preferred embodiment, when the amplitude adjustment rod and the tension-compression fixing rod are vertically arranged, the included angle between the inclined surface structure and the horizontal plane is between 30° and 45°, and the modified layer is more easily expanded along the horizontal plane, and the peeling surface is more flat.

[0018] The driving mechanism can use various devices or components that can output displacement energy. As a preferred embodiment, the driving mechanism is a servo motor, and further preferably a lead screw motor.

[0019] As a further preferred, it further comprises a base, guide rails fixed on both sides of the base, a cross beam slidingly arranged on the top of the guide rails, and the cross beam is connected with the output end of the driving mechanism (when a lead screw motor is selected, the cross beam is threadedly engaged with the lead screw of the lead screw motor, and the rotation of the lead screw is converted into the axial movement of the cross beam); the tension and compression fixing rod is fixed at the bottom end of the base; the ultrasonic transducer and the amplitude adjusting rod are fixed on the cross beam.

[0020] As a preferred, it further comprises a computer, and the computer is used to control the operation of the driving mechanism and the tension or compression limit value.

[0021] As a preferred, it further comprises a force sensor arranged between the driving mechanism and the amplitude adjusting rod, and the force sensor is used to detect the tension or compression force applied to the amplitude adjusting rod, and the driving mechanism is feedback controlled according to the tension or compression value. The computer connected therewith can be used to set a rated tension or compression value, and when the driving mechanism applies a force exceeding the rated value, the computer controls the driving mechanism to stop operating, so as to ensure that the tension or compression applied to the amplitude adjusting rod is no longer increased.

[0022] In actual installation, the force sensor and the ultrasonic transducer can be arranged between the cross beam and the amplitude adjusting rod, and can be connected through bolts (or other connecting members or connecting structures). Meanwhile, the computer (or the computer) can be used to control the tension applied to the amplitude adjusting rod. Meanwhile, the force sensor can be used to read the tension applied by the device in real time.

[0023] Generally, the amplitude adjusting rod and the tension and compression fixing rod can be vertically arranged. The bottom end of the tension and compression fixing rod is fixed to the base, and the top end is provided with the working surface; the bottom end of the amplitude adjusting rod is provided with the working surface, and the top end is fixed to the cross beam together with the ultrasonic transducer.

[0024] As a preferred, the rotation of the ball screw is controlled by a servo motor (lead screw motor), the moving cross beam is driven to move up and down, and the amplitude adjusting rod is driven to move up and down to apply tension to the crystal ingot or wafer.

[0025] As an option, the lead screw motor can be controlled by a computer (or a computer).

[0026] As preferred, a plurality of through-hole structures are arranged in the axial direction in the amplitude adjustment rod and the tension-compression fixing rod. In actual use, the fixing of the wafer to be peeled can be achieved by using an adhesive. When the adhesive needs to be removed after processing, the adhesive can be dissolved and removed by using an organic solvent. By using this technical solution, when the adhesive is removed by using an organic solvent, the organic solvent can contact the bonding surface through the through-hole structure to accelerate the dissolution of the adhesive, so that the peeled wafer is easily removed. At the same time, the problem of difficulty in removing the AB glue commonly used in the prior art is solved. The cross-sectional shape of the through-hole structure can be circular, square, rhombic, etc., and there is no strict limitation.

[0027] As preferred, the through-hole structures are uniformly distributed in the amplitude adjustment rod and / or the tension-compression fixing rod. As further preferred, the cross-sectional area of the through-hole is not less than 30% of the working surface in the plane where the working surface is located.

[0028] One end of the ultrasonic transducer is connected to an ultrasonic generator, and the other end is connected to the amplitude adjustment rod to make it vibrate in the axial direction. The ultrasonic frequency is 10-30 kHz (preferably 20 kHz), and the amplitude of the amplitude adjustment rod is in the range of 5-10 μm.

[0029] As preferred, a tension-compression fixing seat is further included, and the bottom of the tension-compression fixing rod is fixed on the tension-compression fixing seat. As further preferred, the tension-compression fixing seat is fixed on the base. A plurality of fixing hole positions are provided on the base, and a bolt or the like can be used to fix the tension-compression fixing seat relative to the base. At the same time, the plurality of hole positions facilitate the adjustment of the position of the tension-compression fixing seat.

[0030] As preferred, the amplitude adjustment rod and the tension-compression fixing rod are made of titanium alloy or 7075 aviation aluminum.

[0031] A method for peeling by using the ultrasonic-assisted peeling device according to any one of the above technical solutions, comprising the following steps:

[0032] (1) fixing (such as fixing by using an adhesive) two end surfaces of the wafer to be peeled on the working surfaces of the amplitude adjustment rod and the tension-compression fixing rod, respectively;

[0033] (2) fixing the tension-compression fixing rod and the amplitude adjustment rod;

[0034] (3) the driving mechanism applies an axial tensile force or a compressive pressure to the amplitude adjustment rod, and at the same time, the ultrasonic transducer generates ultrasonic vibration to the wafer to be peeled; the ultrasonic vibration applied by the ultrasonic transducer causes the wafer to be peeled to be subjected to fluctuating forces of tension and compression;

[0035] The ultrasonic amplitude can be adjusted to complete the peeling of the wafer to be peeled.

[0036] The adhesive used in the application is a structural adhesive, which can be quickly cured and is soluble in organic solvents; as a preferred, the adhesive used is AB glue.

[0037] As a more specific technical solution, a wafer peeling method based on ultrasonic assistance comprises the following steps:

[0038] (1) The test piece to be peeled is fixed on the amplitude adjusting rod and the tension and pressure fixing rod by an adhesive (such as AB glue);

[0039] (2) The amplitude adjusting rod is connected to the ultrasonic transducer, and the tension and pressure fixing rod is fixed on the tension and pressure fixing seat;

[0040] (3) The lead screw motor applies a constant tension or pressure;

[0041] (4) The ultrasonic generator is turned on after setting the vibration mode and amplitude;

[0042] (5) The test piece to be peeled separates under the action of tension and ultrasonic.

[0043] As a preferred, the test piece to be peeled is a crystal ingot or wafer with a modified layer; as a further preferred, the test piece to be peeled is a crystal ingot or wafer with a laser modified layer. The crystal ingot or wafer is processed by laser to produce a modified layer or crack at a horizontal plane inside a certain depth from the surface.

[0044] The peeling method of the application adopts the method of fixing the test piece (crystal ingot or wafer) to be peeled on the amplitude adjusting rod and the tension and pressure fixing rod by an adhesive; then applying an upward tension or downward pressure to the amplitude adjusting rod, while applying horizontal or axial ultrasonic action; finally, by adjusting the ultrasonic amplitude, the crack is fully expanded, and the wafer is finally peeled. The operation is simple, and the peeling efficiency is high.

[0045] In the application, the lead screw motor can provide a tension of 5N-10000N, and a smaller tension is applied to the test piece to avoid uneven stress caused by excessive tension during peeling, which may cause the crack to be broken. The tension or pressure can also be set to fluctuate at a lower frequency by controlling the software, and the tension or pressure value is an arbitrary waveform force, which can make the test piece to be peeled with smaller force.

[0046] In the application, the ultrasonic wave uses forced vibration mode, so that the amplitude remains stable.

[0047] In the application, the ultrasonic transducer and the amplitude adjusting rod can be connected by bolts, and the amplitude adjusting rod and the tension and pressure fixing rod are made of titanium alloy or 7075 aviation aluminum, which can efficiently convert electrical energy into mechanical energy and keep the amplitude stable.

[0048] The present application increases the peeling lateral force by setting the oblique angle between the peeling surface and the direction of the peeling force, and separates the ingot or wafer with internal modification layer formed after laser modification with smaller force by using ultrasonic oscillation as an auxiliary. The present application discloses the system, process, peeling parameters and result comparison of the peeling method, and embodies the superiority, which proves that the wafer peeling method can realize high quality, fast, quick and simple for the ingot after laser processing, and has wide application prospect in wafer processing of SiC, diamond and other new generation semiconductor materials.

[0049] Compared with the prior art, the present application has the beneficial effects that:

[0050] 1. The working surface with an oblique angle is used to fix the test piece, and only vertical pulling force is needed to be applied by the driving mechanism, so that the modification layer can be subjected to shear stress and tensile stress at the same time, without the need of designing a complex torsion structure.

[0051] 2. The ultrasonic action is performed under the internal stress of the modification layer, which can better guide the crack in the modification layer to expand along the stress direction, reduce the peeling force and improve the peeling quality. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 It is a schematic diagram of wafer peeling process in the embodiment;

[0053] Figure 2 It is a schematic diagram of the device used in the embodiment;

[0054] Figure 3 It is a partial enlarged schematic diagram of the installation structure of the test piece to be peeled in the embodiment;

[0055] Figure 4 It is a schematic diagram of the axial section structure of the amplitude adjusting rod and the tension and compression fixing rod;

[0056] Figure 5 It is a schematic diagram of the structure of the wafer to be peeled in the embodiment;

[0057] Figure 6 It is an enlarged view of the modification layer of the test piece to be peeled in the embodiment;

[0058] Figure 7 It is a schematic diagram of the wafer structure after peeling;

[0059] Figure 8 It is a schematic diagram of the roughness detection of the modification surface of the test piece after peeling;

[0060] Figure 9 It is a schematic diagram of peeling multiple wafers from the ingot. DETAILED DESCRIPTION

[0061] Embodiment 1

[0062] In order to make the technical solutions and advantages of the present application clearer, a SiC wafer with a size of 14mm*14mm*1mm processed by laser is selected as the to-be-peeled piece 400 Figure 2 ) in the process verification stage, and a modified layer with a size of 14mm*14mm*0.05mm is generated in the horizontal plane at a depth in the to-be-peeled piece 400 by reciprocating scanning of a femtosecond laser at a scanning interval of 40μm (focusing depth of the femtosecond laser is 500μm, and the scanning interval is 40μm). The present application will be further described in combination with the drawings and embodiments:

[0063] As shown in Figure 2 , an ultrasonic-assisted wafer peeling device comprises an amplitude adjusting rod 200 with two corresponding working surfaces (an upper working surface 100a and a lower working surface 100b), and a tension and compression fixing rod 500, the two working surfaces are mutually parallel inclined surfaces, and are respectively used for fixing two end surfaces of a to-be-peeled piece 400; an ultrasonic transducer 170 is fixedly connected to the other end of the amplitude adjusting rod 200; a driving mechanism (a stepper motor 130 is selected in the embodiment) is used for driving the amplitude adjusting rod and the tension and compression fixing rod to axially move relative to each other; and the tension and compression fixing rod and the amplitude adjusting rod are coaxial or arranged in parallel with the central axes. The driving mechanism drives two lead screws by a screw motor and a synchronous belt.

[0064] Figure 2 In the embodiment, the device further comprises a base 180, guide rails 190a and 190b fixed on two sides of the base, and a cross beam 150 slidingly arranged on the guide rails. The cross beam 150 is fixed at the bottom ends of the two sides by threadedly cooperating with the lead screws 140a and 140b, and the cross beam 150 is fixed in the middle by bolts and the like to the force sensor 160, the ultrasonic transducer 170 and the amplitude adjusting rod 200. The input end of the ultrasonic transducer is connected to the ultrasonic generator 110. In actual installation, the force sensor 160 is fixedly connected to the bottom end of the cross beam 150, and the ultrasonic transducer 170 is fixed between the force sensor 160 and the top end of the amplitude adjusting rod 200. One of the lead screws 140 is connected to the output shaft of the screw motor 130, and the lead screws 140a and 140b are connected by the synchronous belt 131 to rotate synchronously.

[0065] Figure 2 In the embodiment, the included angle between the upper working surface 100a and the lower working surface 100b and the horizontal plane can be 30-45°. For example, the included angle can be 30°, 35°, 40° or 45°. The following will be described by taking the included angles of 45° and 30° as examples.

[0066] As shown in Figure 1 , an ultrasonic-assisted wafer peeling method using the device shown in Figure 2 comprises the following steps:

[0067] S10: combining Figure 2 , Figure 3、 Figure 4 and Figure 5 The upper surface 420 and the lower surface 440 of the to-be-separated piece are fixed on the upper working surface 100a and the lower working surface 110b of the amplitude adjusting rod 200 and the tension and pressure fixing rod 500 respectively by the adhesive 300, and in this embodiment, the adhesive 300 is selected as AB glue of an epoxy system. The adhesive 300 mainly plays a role of fixing the to-be-separated piece 400. The bonding strength between the AB glue and the surface of the to-be-separated wafer (to-be-separated piece) is relatively large, the deformation is relatively small, and the tension is more easily transmitted to the modified layer when force is applied. In order to facilitate the degreasing, the amplitude adjusting rod 200 and the tension and pressure fixing rod 500 are provided with a through hole structure 210 in the axial direction, so that the degreasing agent can penetrate into the bonding surface through the through hole during subsequent degreasing, thereby facilitating the degreasing;

[0068] S20: After the upper and lower surfaces of the to-be-separated piece 400 are connected to the amplitude adjusting rod 200 and the tension and pressure fixing rod 500 respectively, the amplitude adjusting rod 200 is installed, the tension and pressure fixing rod 500 is fixed on the base, and then the initial tension of 15N is set through the computer 120, the servo motor is controlled to drive the lead screws 140a and 140b to rotate, thereby driving the cross beam 150 to rise, so that the amplitude adjusting rod 200 is subjected to the tension (F) of 15N. Because the working surfaces of the amplitude adjusting rod 200 and the tension and pressure fixing rod 500 are provided with an inclined angle, and the inclined angle is 45 degrees, the modified layer 430 in the to-be-separated piece 400 is respectively subjected to the tensile stress (F y ) of 10.6N and the shear stress (F x ) of 10.6N, and the same effect can be achieved without the need of an external device to provide a torsion, and the system is simpler.

[0069] S30: The frequency of the ultrasonic generator 110 is adjusted to 20kHz, the electric energy of the ultrasonic generator is converted into mechanical energy through the ultrasonic transducer 170, the amplitude of the ultrasonic transducer 170 is set to 5μm, the ultrasonic wave vibrates under the guidance of the tensile stress and the shear stress, the bonding force of the AB glue is greater than that of the internal crack of the wafer, so the modified layer is more easily cracked, the internal crack 431 gradually becomes larger under the continuous action of the ultrasonic wave, and the area 432 without the crack gradually becomes smaller. The amplitude of the ultrasonic wave is continuously increased, the amplitude of the ultrasonic wave is adjusted to 7μm (the time is 30s), the test piece is successfully separated, and the separation force of the test piece is 15N; the to-be-separated piece 400 is separated into two parts of piece one 421 and piece two 441 under the action of the tensile force and the shear force. After the measurement area 510 is selected on the modified surface one 422 and the modified surface two 442 of the piece one 421 and the piece two 441 respectively by using the surface profiler KLA-Tencor P7, the starting position 511 and the measurement direction 512 of the probe are confirmed, the probe starts to scan to obtain the scanning result 520, the surface roughness is automatically calculated from the software according to the scanning position step curve 521, the roughness of the modified surface one 422 is 52.57nm, and the roughness of the modified surface two 442 is 62.17nm.

[0070] In actual application, for other to-be-peeled parts with stronger binding force, if the test piece is still not separated under the action of 15N by adjusting the ultrasonic amplitude (from 5μm to 7μm) and the ultrasonic action for 30s, the pulling force needs to be continuously increased, and the ultrasonic amplitude adjustment process is repeated until the test piece is separated. Finally, the peeling force and peeling amplitude are recorded.

[0071] In order to exclude the influence of random data on the embodiment, the same batch of SiC wafers is selected, the internal laser modification is carried out according to the laser process with a focusing depth of 500μm (consistent with the first piece) and a scanning interval of 40μm, and another group of tests is carried out:

[0072] Test piece 2: when the peeling pulling force is 25N, the ultrasonic amplitude is 7μm, the angle between the amplitude adjustment rod and the pulling and pressing fixed rod is 30 degrees, the SiC test piece is successfully peeled, and the surface profilometer is used to measure the roughness of the two modified surfaces, which are 336.38nm and 290.59nm respectively.

[0073] As a comparison, two SiC test pieces of the same batch and the same laser processing are selected, the upper and lower surfaces are fixed on the amplitude adjustment rod and the pulling and pressing fixed rod without inclination on the end face by AB glue, no ultrasonic action is applied, the cross beam is directly moved upward at a speed of 20mm / min by driving the screw rod by the motor, until the wafer is divided into two parts, and the force at the moment of peeling is recorded as the peeling force:

[0074] Test piece 3: the direct peeling force is 325N, and the step gauge is used to measure the roughness of the two modified surfaces after peeling, which are 12.82μm and 23.36μm respectively.

[0075] Test piece 4: the direct peeling force is 431N, and one of the separated pieces has a broken corner, and the step gauge is used to measure the roughness of the two modified surfaces after peeling, which are 23.43μm and 23.25μm respectively.

[0076] Through a large number of repeated tests, the wafer can be separated with high quality within 30s under the action of ultrasonic at a pulling force of 25N and an amplitude of 7μm (the working surface inclination is 45°). The wafer peeling force has a linear relationship with the size of the wafer. For the same laser process and to-be-peeled solid materials, the test results of the above four groups of tests are used to calculate the peeling force of 4-inch and 6-inch wafers, which are shown in the following table:

[0077]

[0078]

[0079] The above results show that the peeling force required for the device to peel the SiC sample after laser modification is smaller than the peeling force required for directly applying vertical tension peeling with a horizontal fixed, which can greatly reduce the tension required for peeling the wafer, and in turn reduce the risk of cracking caused by excessive peeling force.

[0080] Embodiment 2:

[0081] According to embodiment 1, according to the crystal ingot of different materials (such as silicon carbide, diamond, etc.), the laser parameters are optimized, the optimized peeling force and ultrasonic parameters are used after laser processing, and the wafer 601, wafer 602, wafer 603, etc. are peeled from the crystal ingot 600 according to the same method process as embodiment 1. The crystal ingot 600 is usually cylindrical, the diameter is usually 100mm-200mm, and the thickness will decrease with the increase of the number of peeled wafers.

Claims

1. An ultrasonic assisted peeling device, characterized by The utility model relates to an ultrasonic auxiliary stripping device, comprising: a tension-compression fixed rod and an amplitude adjusting rod with two corresponding working surfaces, the two working surfaces are mutually parallel inclined surface structures, and are respectively used for fixing two end surfaces of a to-be-stripped piece; an ultrasonic transducer fixedly connected to the other end of the amplitude adjusting rod; a driving mechanism for driving the amplitude adjusting rod and the tension-compression fixed rod to axially move relative to each other; the tension-compression fixed rod and the amplitude adjusting rod are coaxial or have parallel central axes; when the amplitude adjusting rod and the tension-compression fixed rod are vertically arranged, the included angle between the two working surfaces and a horizontal plane is 30°-45°; a plurality of through hole structures are arranged in the amplitude adjusting rod and the tension-compression fixed rod in the axial direction; one end of the ultrasonic transducer is connected to an ultrasonic generator, and the other end is connected to the amplitude adjusting rod to make the amplitude adjusting rod vibrate in the axial direction; the ultrasonic frequency is 10-30 kHz, and the amplitude adjusting rod has an amplitude range of 5-10 μm; a force sensor is further arranged between the driving mechanism and the amplitude adjusting rod, the force sensor is used for detecting the pressure or tension of the amplitude adjusting rod, and feedback control is performed on the driving mechanism according to the pressure value or tension value.

2. The ultrasound-assisted peeling apparatus of claim 1, wherein a plurality of through hole structures are arranged in the amplitude adjusting rod and the tension-compression fixed rod in the axial direction, and the through hole structures are uniformly distributed.

3. The ultrasound-assisted peeling apparatus of claim 1, wherein, a base, guide rails fixed to two sides of the base, and a cross beam slidingly arranged on the top of the guide rails are further included, the cross beam is connected to the output end of the driving mechanism; the bottom end of the tension-compression fixed rod is fixed to the base; the ultrasonic transducer and the amplitude adjusting rod are fixed to the cross beam.

4. The ultrasound-assisted peeling apparatus according to any one of claims 1 to 3, characterized in that the driving mechanism is a lead screw motor.

5. A method for stripping by using the ultrasonic auxiliary stripping device according to any one of claims 1-4, comprising the following steps: (1) fixing two end surfaces of a to-be-stripped piece on the working surfaces of the amplitude adjusting rod and the tension-compression fixed rod, respectively; (2) installing the tension-compression fixed rod, the amplitude adjusting rod, and the ultrasonic transducer; (3) the driving mechanism applies axial tension or compression to the amplitude adjusting rod, and the ultrasonic transducer generates ultrasonic vibration to the to-be-stripped piece; the amplitude of the ultrasonic vibration or the tension or compression of the driving mechanism can be adjusted to complete the stripping of the to-be-stripped piece; the to-be-stripped piece is a laser-modified wafer.

6. The method of peeling according to claim 5, wherein, the to-be-stripped piece is a wafer or a crystal ingot with a laser-modified layer; in step (1), an adhesive is used to fix the two end surfaces of the to-be-stripped piece to the two working surfaces.

7. The method of peeling according to claim 5, wherein the driving mechanism is controlled by a computer, and the tension or compression limit value is calculated.

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