CN115029785A - Ultrasonic auxiliary stripping device and method - Google Patents
Ultrasonic auxiliary stripping device and method Download PDFInfo
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- CN115029785A CN115029785A CN202210786631.5A CN202210786631A CN115029785A CN 115029785 A CN115029785 A CN 115029785A CN 202210786631 A CN202210786631 A CN 202210786631A CN 115029785 A CN115029785 A CN 115029785A
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- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
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Abstract
The invention discloses an ultrasonic auxiliary stripping device, which comprises: the device comprises a tension and compression fixing rod and an amplitude adjusting rod, wherein the tension and compression fixing rod and the amplitude adjusting rod are provided with two corresponding working surfaces, and the two working surfaces are of inclined surface structures which are parallel to each other and are respectively used for fixing two end surfaces of a piece to be stripped; the ultrasonic transducer is fixedly connected to the other end of the amplitude adjusting rod; the driving mechanism drives the amplitude adjusting rod and the tension and compression fixing rod to axially and relatively move; the pulling and pressing fixed rod and the amplitude adjusting rod are coaxial or the central shafts are arranged in parallel. The invention increases the stripping lateral force by setting the inclined included angle between the stripping surface and the stripping force direction, and simultaneously takes the ultrasonic oscillation as the assistance to ensure that the crystal ingot or the wafer with the internal modified layer formed after laser modification is separated by smaller force. The invention can realize a high-quality, rapid, convenient and simple wafer stripping mode for the crystal ingot after laser processing, and has wide application prospect in the wafer processing of the new generation of semiconductor materials such as SiC, diamond and the like.
Description
Technical Field
The invention belongs to the technical field of wafer stripping, and particularly relates to a stripping method for dividing a solid material into two parts.
Background
In the semiconductor industry, in order to separate wafers from ingots, the wafers are usually obtained directly from the ingots by conventional wire cutting, and for some solid materials (such as SiC, diamond, etc.) which have relatively high hardness and are relatively expensive, the wire cutting not only has low production efficiency, but also causes great loss.
In order to improve the efficiency and reduce the loss, a laser processing method is adopted, a modified layer is firstly generated in the ingot, and then the crystal is processedThe ingot is separated from the wafer. But is limited by the fact that the force required for direct stripping is large, unlike current laser processes and the solid material to be separated. In the research report of Precision laser cutting technique for single crystal SiC wafers by Hippocampus, et al (Y.YAMADA, T.IKEDA and J.IKENO: Precision laser slicing technology for single crystal SiC wafer 1st report: Study on slicing method for slicing kerf-loss, J.Jpn.Soc.Abras.Techno., 64,12(2020)635(in Japan) 10.11420/jsat.64.635): peeling scan interval of 20 μm 1cm 2 The force required for the SiC squares of (1) is 1110N, which is 11.1MPa, and the force required for peeling SiC chips having a scanning pitch of 40 μm is 2500N, which is 25MPa, which is 2500N, and if a 6-inch wafer is peeled under a peeling stress of this order, an extremely large facility is required, and the surface profile of the wafer inevitably deteriorates, and chipping occurs in a serious case. Therefore, the lift-off technology is one of the key technologies for realizing industrialization of the current semiconductor material laser dicing technology.
In patent document No. CN 113714649 a, entitled as a method for manufacturing a chip, a method for separating a chip is provided, which utilizes the expansion and contraction effects of materials with different thermal expansion coefficients during temperature changes to generate stress in the chip to promote the separation of the chip, but when the solid colloid material is heated to a liquid state or a molten state, the adhesive force of the adhesive layer is reduced and cannot be tightly adhered to the chip, and the colloid expands with heat and contracts with cold during cooling, so that the stress is hardly transferred to the modified layer.
A patent document with publication No. CN 111889896 a entitled ingot peeling method by ultrasonic cooperating with laser discloses a typical ultrasonic assisted method of peeling a wafer, which has the following disadvantages: on the one hand, for the ingot with the peeling thickness of 200-600 μm, the thickness of the modified layer is usually less than 50 μm, and when the ultrasonic tool head applies ultrasonic waves to the lateral surface of the ingot, precise alignment is difficult to achieve. Without precise alignment, ultrasound forces at the unmodified layer portion of the ingot. When the modified layer is vibrated, the wafer to be stripped and the crystal ingot are simultaneously vibrated, the modified layer is not stressed, and cracks are difficult to form and expand on a horizontal plane. On the other hand, the common crystal ingots are provided with the edge cutting structures and are not in complete cylindrical shapes, when the edges are cut to the inner arc surface of the ultrasonic tool head, the part cannot be attached to the ultrasonic tool head, and effective vibration cannot be formed, so that the method is difficult to realize in practical equipment and cannot be applied to the wafer stripping process after laser processing.
In patent document CN103579042A entitled system and method for separating bonded wafers, a system for separating bonded wafers is provided, in which a shear force is applied to the bonded wafers for separation, but two sets of vacuum devices are required for fixing upper and lower surfaces during separation, and the bonded upper and lower wafers are twisted in opposite directions by two sets of servo motors and ball screws, so that an expensive external mechanism is required for generating the shear force, and for some wafers with relatively large bonding force, the chuck is easily detached, resulting in separation failure. In addition, since the inside of the wafer after laser processing still has strong connecting force, and a large torque is required only by twisting, the equipment is huge, the surface shape of the wafer is damaged, the warpage of the wafer is increased, and the wafer is cracked in a serious case, so that the simple shearing force separation cannot be applied to the separation of the wafer after laser processing.
For the demand of wafer lift-off after laser processing, the currently disclosed schemes cannot realize an effective lift-off mode with high quality, rapidness, simplicity and convenience, so that a new scheme is urgently needed to solve the problem.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a wafer stripping device and method based on ultrasonic assistance. Compared with the traditional method of simply applying pulling force or twisting separation, the method has the advantages that the force required for stripping is smaller, the stripping surface cracks are smoother, and the splinters cannot be generated.
An ultrasonically assisted detachment apparatus comprising:
the device comprises a tension and compression fixing rod and an amplitude adjusting rod, wherein the tension and compression fixing rod and the amplitude adjusting rod are provided with two corresponding working surfaces, and the two working surfaces are of inclined surface structures which are parallel to each other and are respectively used for fixing two end surfaces of a piece to be stripped;
the ultrasonic transducer is fixedly connected to the other end of the amplitude adjusting rod;
the driving mechanism drives the amplitude adjusting rod and the tension and compression fixing rod to axially and relatively move;
the pulling and pressing fixed rod and the amplitude adjusting rod are coaxial or the central shafts are arranged in parallel.
In the invention, one end of each of the tension and compression fixing rod and the amplitude adjusting rod is provided with an inclined working surface, and the two working surfaces are correspondingly arranged and used for fixing two end surfaces of a piece to be stripped. During actual installation, two end faces of a piece to be stripped need to be fixed with a pulling and pressing fixed rod and one end of an amplitude adjusting rod respectively, then the pulling and pressing fixed rod is fixed, and then the other end of the amplitude adjusting rod is connected with an ultrasonic transducer; and finally, moving the position of the output end of the driving mechanism, and fixing the amplitude adjusting rod, the ultrasonic transducer and the output end (and the force measuring sensor) of the driving mechanism after the driving mechanism is moved to a proper position.
The ultrasonic transducer is generally connected with another ultrasonic generator and used for converting electric energy into ultrasonic mechanical energy, and the generated mechanical energy is transmitted to a piece to be stripped along the amplitude adjusting rod to realize auxiliary stripping. The invention adopts the ultrasonic wave transmitted axially, thereby avoiding the problem that the ultrasonic wave in the horizontal direction is difficult to align to the modified layer in the prior art.
The invention adopts the working surface with the inclined surface structure, ensures that when axial acting force is applied, acting force in two directions is generated on the modified layer of the piece to be stripped, one is tensile stress vertical to the modified layer, and the other is shear stress outwards along the plane of the modified layer, and the same effect can be achieved without providing torsion by an external device, and the system is simpler.
Preferably, when the amplitude adjusting rod and the tension and compression fixing rod are vertically arranged, the included angle between the two working surfaces and the horizontal plane is 25-50 degrees. Preferably, when the amplitude adjusting rod and the tension and compression fixing rod are vertically arranged, the included angle between the inclined surface structure and the horizontal plane is 30-45 degrees, the modified layer is easier to expand along the horizontal plane, and the stripping surface is smoother.
The drive mechanism may employ various devices or components capable of outputting displacement energy. Preferably, the drive mechanism is a servo motor, and more preferably a screw motor.
As further preferred, still include the base, fix the guide rail on both sides of the base, set up the crossbeam on the top of the guide rail slidably, the crossbeam couples to carry-out terminal of the actuating mechanism (when choosing the feed screw motor, the crossbeam cooperates with lead screw thread of the feed screw motor, turn the rotation of the feed screw into the axial displacement of the crossbeam); the bottom end of the tension and compression fixing rod is fixed on the base; the ultrasonic transducer and the amplitude adjusting rod are fixed on the cross beam.
Preferably, a computer is also included, by means of which the operation of the drive mechanism and the tension or pressure limit values are controlled.
Preferably, the vibration amplitude adjusting device further comprises a force measuring sensor arranged between the driving mechanism and the amplitude adjusting rod, wherein the force measuring sensor is used for detecting pressure or pulling force applied to the amplitude adjusting rod and carrying out feedback control on the driving mechanism according to the pressure value or the pulling force value. The computer can be used for setting a rated pressure or tension value, and when the acting force applied by the driving mechanism exceeds the rated value, the computer controls the driving mechanism to stop running, so that the pressure or the tension applied to the amplitude adjusting rod is ensured not to be increased any more.
In actual installation, a load cell and an ultrasonic transducer can be arranged between the cross beam and the amplitude adjusting rod and can be connected through bolts (or other connecting pieces or connecting structures). Meanwhile, the computer (or the computer) can be used for controlling the tension force applied to the amplitude adjusting rod. Meanwhile, the tension applied by the device can be read in real time by utilizing the force transducer.
In general, 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 with the base, and the top end of the tension and compression fixing rod is provided with the working surface; the bottom end of the amplitude adjusting rod is provided with the working surface, and the top end of the amplitude adjusting rod and the ultrasonic transducer are fixed together with the cross beam.
Preferably, the servo motor (screw motor) controls the rotation of the ball screw to drive the moving beam to move up and down, and further drives the amplitude adjusting rod to move up and down to apply tension to the crystal ingot or the wafer.
Alternatively, the screw motor may be controlled by a computer (or computers).
Preferably, a plurality of through hole structures are arranged in the amplitude adjusting rod and the tension and compression fixing rod along the axial direction. When the invention is practically used, the fixing of the piece to be peeled can be realized by adopting an adhesive. When the adhesive needs to be removed after the processing is completed, the adhesive can be dissolved and removed by using an organic solvent. By adopting the technical scheme, when the adhesive is removed by using the 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 convenient to take down. Meanwhile, the problem that the AB glue adopted in the prior art is difficult to remove is solved. The cross section of the through hole structure can be circular, square, diamond and the like without strict limitation.
Preferably, the through hole structures are uniformly distributed in the amplitude adjusting rod or/and the tension and compression fixing rod. More preferably, the cross-sectional area of the through-hole is not less than 30% of the working surface on the plane of the working surface.
One end of the ultrasonic transducer is connected with an ultrasonic generator, the other end of the ultrasonic transducer is connected with an amplitude adjusting rod to enable the ultrasonic transducer to vibrate in the axial direction, the ultrasonic frequency is 10-30 kHz (preferably 20kHz), and the amplitude range of the amplitude adjusting rod is 5-10 mu m.
Preferably, the device further comprises a tension and compression fixing seat, and the bottom of the tension and compression fixing rod is fixed on the tension and compression fixing seat. Preferably, the tension-compression fixing seat is fixed on the base. The base is provided with a plurality of fixing hole positions, and bolts and the like can be used for fixing the tension and compression fixing seat relative to the base. Meanwhile, the positions of the tension and compression fixing seats can be conveniently adjusted through a plurality of hole positions.
Preferably, the amplitude adjusting rod and the tension and compression fixing rod are processed by titanium alloy or 7075 aviation aluminum.
The method for stripping by using the ultrasonic auxiliary stripping device in any technical scheme comprises the following steps:
(1) respectively fixing two end faces of the piece to be stripped (for example, fixing by using an adhesive) on the working faces of the amplitude adjusting rod and the tension and compression fixing rod;
(2) the fixed rod and the amplitude adjusting rod are fixedly pulled and pressed;
(3) the driving mechanism applies axial far-away pulling force or pressing force to the amplitude adjusting rod, and meanwhile, the ultrasonic transducer generates ultrasonic vibration to the stripping part; the ultrasonic vibration effect exerted by the ultrasonic transducer enables the stripping part to be subjected to the wave power of tension and pressure;
and optionally adjusting the ultrasonic amplitude to complete the stripping of the piece to be stripped.
The adhesive used in the invention is a structural adhesive, can be rapidly cured and can be dissolved in an organic solvent; preferably, the adhesive used is an AB glue.
As a more specific technical scheme, the wafer peeling method based on ultrasonic assistance comprises the following steps:
(1) fixing a test piece to be stripped on the amplitude adjusting rod and the tension and compression fixing rod through an adhesive (such as AB glue);
(2) the amplitude adjusting rod is connected with an ultrasonic transducer, and the tension and compression fixing rod is fixed on the tension and compression fixing seat;
(3) the screw motor applies constant tension or pressure;
(4) the ultrasonic generator is started after setting the vibration mode and the amplitude;
(5) the test piece to be peeled is separated under the action of tensile force and ultrasonic wave.
Preferably, the piece to be stripped is an ingot or a wafer with a modified layer; as a further preference, the member to be peeled is an ingot or a wafer having a laser-modified layer. The ingot or wafer is laser machined to produce a modified layer or crack at a depth level within the ingot or wafer from the surface.
The stripping method of the invention adopts the steps that a test piece (crystal ingot or wafer) to be stripped is fixed on an amplitude adjusting rod and a tension and compression fixing rod through an adhesive; then applying upward tension or downward pressure to the amplitude adjusting rod, and simultaneously applying ultrasonic action in the horizontal direction or the axial direction; and finally, adjusting the ultrasonic amplitude to fully expand the crack, and finally peeling off the wafer. The operation is simple, and the stripping efficiency is high.
According to the invention, the screw rod motor can provide 5N-10000N of pulling force, and the pulling force is preferably used for applying fixed smaller pulling force to a test piece, so that the splintering caused by uneven stress at the moment of peeling due to overlarge pulling force is avoided. The pulling force or the pressure which fluctuates at a lower frequency can also be set through the control software, and the pulling force or the pressure value is the force with any waveform, so that the piece to be peeled can be peeled with smaller force.
In the invention, the ultrasound adopts a forced vibration mode, so that the amplitude is kept stable.
According to the invention, the ultrasonic transducer and the amplitude adjusting rod can be connected through bolts, and the amplitude adjusting rod and the tension and compression fixing rod are made of titanium alloy or 7075 aviation aluminum, so that electric energy can be efficiently converted into mechanical energy and the amplitude is stable.
The invention increases the stripping lateral force by setting the inclined included angle between the stripping surface and the stripping force direction, and simultaneously takes the ultrasonic oscillation as the assistance to separate the crystal ingot or the wafer which forms the internal modified layer after the laser modification with smaller force. The invention discloses a system, a flow, stripping parameters and result comparison for stripping by the method, embodies superiority, proves that a high-quality, rapid, quick and simple wafer stripping mode can be realized for a crystal ingot after laser processing, and the method has wide application prospect in wafer processing of new-generation semiconductor materials such as SiC, diamond and the like.
Compared with the prior art, the invention has the beneficial effects that:
1. the working surface with the oblique angle is adopted to fix the test piece, and only the driving mechanism is needed to apply the vertical tension, so that the modified layer can be subjected to the shear stress and the tensile stress at the same time, and a complex torsion structure is not required to be designed.
2. The ultrasonic action is carried out under the condition that the inside of the modified layer is stressed, so that the cracks in the modified layer can be better guided to expand along the stress direction, the stripping force is reduced, and the stripping quality can be improved.
Drawings
FIG. 1 is a schematic diagram illustrating an exemplary wafer lift-off process;
FIG. 2 is a schematic view of an apparatus employed in the examples;
FIG. 3 is a partially enlarged schematic view of a mounting structure of a test piece to be peeled in the embodiment;
FIG. 4 is a schematic view of an axial cross-sectional structure of an amplitude adjusting rod and a tension/compression fixing rod;
FIG. 5 is a schematic structural view of a wafer to be peeled off employed in the present embodiment;
FIG. 6 is an enlarged view of a modified layer of a test piece to be peeled employed in the example;
FIG. 7 is a schematic view of a wafer structure after being peeled;
FIG. 8 is a schematic diagram illustrating roughness measurement of a modified surface of a test piece after peeling;
fig. 9 is a schematic view of a plurality of wafers being stripped from an ingot.
Detailed Description
Example 1
In order to make the technical scheme and advantages of the present invention clearer, a SiC wafer with the size of 14mm x 1mm processed by laser is selected as a to-be-stripped part 400 (fig. 2) in a process verification stage, and a modified layer with the size of 14mm x 0.05mm generated by the femtosecond laser in a reciprocating scanning manner along a horizontal plane at a distance of 40 μm is arranged in a certain depth (the focusing depth of the femtosecond laser is 500 μm, and the scanning distance is 40 μm), and the present invention is further explained by combining the attached drawings and an embodiment:
as shown in fig. 2, an ultrasonic-assisted wafer peeling apparatus includes: the device comprises an amplitude adjusting rod 200 and a tension and compression fixing rod 500 which are provided with two corresponding working surfaces (an upper working surface 100a and a lower working surface 100b), wherein the two working surfaces are of inclined surface structures which are parallel to each other and are respectively used for fixing with two end surfaces of a piece 400 to be stripped; an ultrasonic transducer 170 fixedly connected to the other end of the amplitude adjusting rod 200; a driving mechanism (in this embodiment, the stepping motor 130 is selected) for driving the amplitude adjusting rod and the tension/compression fixing rod to move axially relatively; the pulling and pressing fixed rod and the amplitude adjusting rod are coaxial or the central shafts are arranged in parallel. The driving mechanism adopts a screw motor and a synchronous belt to drive two screws for driving.
In fig. 2, the method also includes: the base 180, the guide rails 190a and 190b fixed on both sides of the base, and the cross beam 150 slidably disposed on the guide rails. The bottom ends of both sides of the beam 150 are fixed with the screw threads of the lead screws 140a and 140b in a matching manner, and the middle of the beam 150 is fixed with the load cell 160, the ultrasonic transducer 170 and the amplitude adjusting rod 200 by bolts and the like. The input of the ultrasonic transducer is connected to an ultrasonic generator 110. During actual installation, the load cell 160 is fixedly connected with the bottom end of the beam 150; the ultrasonic transducer 170 is fixed between the load cell 160 and the tip of the amplitude adjustment rod 200. One of the lead screws 140 is connected to an output shaft of the lead screw motor 130, and the lead screw 140a and the lead screw 140b are connected through a timing belt 131 to perform synchronous rotation.
In fig. 2, the upper working surface 100a and the lower working surface 100b may form an angle of 30 to 45 ° with the horizontal plane. For example, it may be 30 °, 35 °, 40 °, 45 °, etc. The bevel angles of 45 ° and 30 ° will be described below as examples.
As shown in fig. 1: an ultrasonic-assisted wafer lift-off method using the apparatus of fig. 2, comprising the steps of:
and S10, referring to the figures 2, 3, 4 and 5, respectively fixing the upper surface 420 and the lower surface 440 of the to-be-peeled off piece on the upper working surface 100a and the lower working surface 110b of the amplitude adjusting rod 200 and the tension and compression fixing rod 500 through the adhesive 300, wherein in the embodiment, the adhesive 300 is AB glue of an epoxy system, and the adhesive 300 mainly plays a role in fixing the to-be-peeled off piece 400. The AB glue and the wafer to be separated (a piece to be peeled) have higher surface bonding strength and smaller deformation, and the pulling force is more easily transmitted to the modified layer when the AB glue is stressed. In order to facilitate the removal of the glue, the amplitude adjusting rod 200 and the tension and compression fixing rod 500 are provided with through hole structures 210 along the axial direction, so that the glue removing agent can conveniently permeate into the bonding surface through the through holes during the subsequent glue removing process, and the glue can be removed more easily;
s20, after the upper and lower surfaces of the piece 400 to be peeled are respectively connected with the amplitude adjusting rod 200 and the tension and compression fixing rod 500, the amplitude adjusting rod 200 is installed, the tension and compression fixing rod 500 is fixed on a base, then the computer 120 sets 15N initial tension, controls the servo motor to drive the screw rod 140a and the screw rod 140b to rotate, further drives the beam 150 to rise, so that the amplitude adjusting rod 200 is subjected to 15N tension (F), and the amplitude adjusting rod 200 and the tension and compression fixing rod 500 are connectedThe working surface has a bevel angle of 45 degrees, and the modified layers 430 in the member 400 to be peeled are respectively subjected to a tensile stress (F) of 10.6N y ) And a shear stress (F) of 10.6N x ) The same effect can be achieved without providing torque force by an external device, and the system is simpler.
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 be 5 mu m, the ultrasonic is vibrated under the guide of tensile stress and shearing stress, the bonding force of the AB glue is larger than that of the cracks in the wafer, so the modified layer is easier to crack, the internal cracks 431 are gradually enlarged under the continuous action of the ultrasonic, the area 432 without the cracks is gradually reduced, the ultrasonic amplitude is continuously increased in the period, the test piece is successfully separated when the ultrasonic amplitude is adjusted to be 7 mu m (the time is 30s), and 15N is the peeling force of the test piece; the member to be peeled 400 is separated into a first member 421 and a second member 441 under the action of tensile force and shearing force. After a measurement area 510 is selected on a first modified surface 422 and a second modified surface 442 corresponding to a first piece 421 and a second piece 441 respectively by using a surface profiler KLA-Tencor P7, after a measurement starting position 511 and a measurement direction 512 of a probe are confirmed, the probe starts to scan to obtain a scanning result 520, the surface roughness is automatically calculated by software according to a scanning position step curve 521, the roughness of the first modified surface 422 is 52.57nm, and the roughness of the second modified surface 442 is 62.17 nm;
in practical application, for other to-be-peeled pieces with stronger bonding force, if the ultrasonic amplitude (from 5 μm to 7 μm) is adjusted under the action of 15N and the test piece is not separated yet after the ultrasonic action for 30s, the tensile force needs to be increased continuously, and the ultrasonic amplitude adjustment process is repeated until the test piece is separated and the final peeling force and the peeling amplitude are recorded.
In order to eliminate the influence of random data on the examples, the same batch of SiC wafers were selected, and the interior thereof was subjected to laser modification according to a laser process with a focal depth of 500 μm (the depth was consistent with that of the first wafer) and a scanning pitch of 40 μm, and 1 set of tests were additionally performed:
test piece 2: when the stripping tension is 25N, the ultrasonic amplitude is 7 microns, and the bevel angle of the amplitude adjusting rod and the tension and compression fixing rod is 30 degrees, the SiC test piece is successfully stripped, and the roughness of two modified surfaces measured by a surface profiler is 336.38nm and 290.59nm respectively.
As a comparison, two SiC samples of the same batch and the same laser processing technology are selected, the upper surface and the lower surface of the SiC samples are fixed on an amplitude adjusting rod and a tension and compression fixing rod of which the end surfaces have no inclination angle through AB glue, the ultrasonic action is not exerted, the screw rod is directly driven to rotate through the motor, so that the beam moves upwards at the speed of 20mm/min until the wafer is divided into two parts, and the instantaneous force of stripping is recorded as the stripping force:
test piece 3: the direct peeling force was 325N, and the roughness of the two modified surfaces after peeling was measured by a step meter to be 12.82 μm and 23.36 μm, respectively.
Test piece 4: the direct peeling force is 431N, one of the modified surfaces has a broken corner after separation, and the roughness of the two modified surfaces after peeling is respectively 23.43 mu m and 23.25 mu m measured by a step instrument.
After a large number of repeated experiments, the high-quality separation of the wafer can be realized within 30 seconds by applying ultrasonic waves when the tensile force is 25N and the amplitude is 7 mu m (the inclination angle of a working surface is 45 degrees). The chip peel force is linear with the chip size, and for the same laser process and solid material to be peeled, the peel force for peeling 4 "and 6" wafers is calculated and compared according to the test results of the above four sets of tests as shown in the following table:
the results show that the stripping force required by the device for stripping the laser modified SiC sample is smaller than that required by horizontally fixing and directly applying vertical pulling force for stripping, so that the pulling force required by stripping the wafer can be greatly reduced, and further, the risk of cracking caused by overlarge stripping force is reduced.
Example 2:
according to embodiment 1, laser parameters are optimized in a targeted manner according to ingots of different materials (such as silicon carbide, diamond and the like), wafers 601, 602, 603 and the like are stripped from the ingot 600 according to the same method flow as embodiment 1 after laser processing by using corresponding optimized stripping force and ultrasonic parameters, wherein the ingot 600 is generally cylindrical and has a diameter of generally 100mm-200mm, and the thickness is reduced along with the increase of the number of stripped wafers.
Claims (10)
1. An ultrasonically assisted detachment apparatus, comprising:
the device comprises a tension and compression fixing rod and an amplitude adjusting rod, wherein the tension and compression fixing rod and the amplitude adjusting rod are provided with two corresponding working surfaces, and the two working surfaces are of inclined surface structures which are parallel to each other and are respectively used for fixing two end surfaces of a piece to be stripped;
the ultrasonic transducer is fixedly connected to the other end of the amplitude adjusting rod;
the driving mechanism drives the amplitude adjusting rod and the tension and compression fixing rod to axially and relatively move;
the pulling and pressing fixed rod and the amplitude adjusting rod are coaxial or the central shafts are arranged in parallel.
2. The ultrasonic assisted debonding device of claim 1, wherein when the amplitude adjusting lever and the tension/compression fixing lever are vertically disposed, the included angle between the two working planes and the horizontal plane is 25 ° to 50 °.
3. The ultrasonic-assisted debonding device according to claim 1, wherein a plurality of through hole structures are axially disposed in the amplitude adjusting rod and the tension-compression fixing rod.
4. The ultrasonic-assisted debonding device of claim 3, wherein the through-hole structures are uniformly distributed within the amplitude adjusting bars and the tension/compression fixing bars.
5. The ultrasonic-assisted peeling apparatus of claim 1, further comprising a base, guide rails fixed on both sides of the base, and a beam slidably disposed on top of the guide rails, the beam being connected to an output end of the driving mechanism; the bottom end of the tension and compression fixing rod is fixed on the base; the ultrasonic transducer and the amplitude adjusting rod are fixed on the cross beam.
6. The ultrasonic-assisted peeling apparatus of claim 1, further comprising a load cell disposed between the driving mechanism and the amplitude adjustment lever, the load cell being configured to detect a pressure or a tension applied to the amplitude adjustment lever and perform feedback control on the driving mechanism according to a magnitude of the pressure or the tension.
7. The ultrasonically assisted debonding apparatus of any one of claims 1-6, wherein the driving mechanism is a lead screw motor.
8. A method of exfoliation using an ultrasound-assisted exfoliation apparatus as defined in any one of claims 1 to 7, comprising the steps of:
(1) fixing two end faces of a piece to be stripped on working faces of the amplitude adjusting rod and the tension and compression fixing rod respectively;
(2) installing a tension and compression fixing rod, an amplitude adjusting rod and an ultrasonic transducer;
(3) the driving mechanism applies axial far-away pulling force or pressing force to the amplitude adjusting rod, and meanwhile, the ultrasonic transducer generates ultrasonic vibration to the stripping part;
optionally adjusting the ultrasonic amplitude or the tension or pressure of the driving mechanism to complete the stripping of the piece to be stripped; the piece to be stripped is a laser modified wafer.
9. The method for peeling off as claimed in claim 8, wherein the member to be peeled off is a wafer or ingot with a laser modified layer; in the step (1), the two end faces of the piece to be stripped and the two working faces are fixed by using an adhesive.
10. The method of stripping as set forth in claim 8 wherein operation of the drive mechanism and the tension or pressure limit are computer controlled.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115223851A (en) * | 2022-09-21 | 2022-10-21 | 西北电子装备技术研究所(中国电子科技集团公司第二研究所) | Mechanical wafer separation method and device |
| CN116093006A (en) * | 2023-03-06 | 2023-05-09 | 西北电子装备技术研究所(中国电子科技集团公司第二研究所) | SiC wafer high-low frequency composite vibration heating stripping device and SiC wafer preparation method |
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2022
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|---|---|---|---|---|
| CN115223851A (en) * | 2022-09-21 | 2022-10-21 | 西北电子装备技术研究所(中国电子科技集团公司第二研究所) | Mechanical wafer separation method and device |
| CN115223851B (en) * | 2022-09-21 | 2022-12-09 | 西北电子装备技术研究所(中国电子科技集团公司第二研究所) | Mechanical wafer separation method and device |
| CN116093006A (en) * | 2023-03-06 | 2023-05-09 | 西北电子装备技术研究所(中国电子科技集团公司第二研究所) | SiC wafer high-low frequency composite vibration heating stripping device and SiC wafer preparation method |
| CN116093006B (en) * | 2023-03-06 | 2023-07-25 | 西北电子装备技术研究所(中国电子科技集团公司第二研究所) | SiC wafer high-low frequency composite vibration heating stripping device and SiC wafer preparation method |
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