CN111702353A - Laser wafer peeling device and laser wafer peeling method - Google Patents
Laser wafer peeling device and laser wafer peeling method Download PDFInfo
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- CN111702353A CN111702353A CN202010625189.9A CN202010625189A CN111702353A CN 111702353 A CN111702353 A CN 111702353A CN 202010625189 A CN202010625189 A CN 202010625189A CN 111702353 A CN111702353 A CN 111702353A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/50—Working by transmitting the laser beam through or within the workpiece
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/0643—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising mirrors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/70—Auxiliary operations or equipment
- B23K26/702—Auxiliary equipment
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Abstract
The application provides a laser wafer stripping device and a laser wafer stripping method, and relates to the field of semiconductor processing. The laser wafer stripping device comprises a mounting platform for mounting a crystal ingot, a laser emitter, a lens gathering component, a magnet for providing a magnetic field and a control system; the laser emitter and the condenser lens assembly cooperate to focus the laser beam into the ingot to induce the ingot to generate a plasma; the crystal ingot is positioned in the magnetic field so that the magnetic field can regulate and control the motion state of the plasma; the control system is connected with the magnet and can obtain the characteristic parameters of the plasma in real time and regulate and control the magnetic field of the crystal ingot in real time according to the characteristic parameters. The laser wafer stripping device and the laser wafer stripping method regulate and control the laser-induced plasma through the magnetic field, change the motion process of the plasma in the crystal ingot in real time to carry out secondary processing on the modified layer, realize the secondary processing of the processed surface of the wafer, and greatly improve the quality and the efficiency of the wafer stripping processing from the crystal ingot.
Description
Technical Field
The application relates to the field of semiconductor processing, in particular to a laser wafer stripping device and a laser wafer stripping method.
Background
As a base material of a semiconductor device, a wafer is mainly obtained by ingot peeling, and is processed by a subsequent process to obtain a substrate or an epitaxial wafer for manufacturing a chip. The thickness of the wafer is usually only in the order of hundreds of microns, and the processing quality thereof is greatly affected by the ingot stripping process. At present, wafers are mainly obtained by ingot linear cutting, but the defects of line marks, warping and the like easily occur on the processing surface due to the hard and brittle characteristics of ingot materials, and the defects need to be removed through subsequent procedures of flattening, grinding, polishing and the like, so that the working efficiency is low. In addition, the wear of the semiconductor material and the tool is large, which increases the processing cost.
A series of problems caused by linear cutting are avoided to the greatest extent by adopting a laser processing mode, but the high-energy beam processing mode easily causes heat influence on the processing surface and the processing interior of the material, and generates defects of microcracks, recast layers and the like, and simultaneously plasma generated by induction in the laser processing process also reduces the controllability of the processing process.
In view of this, the present application is hereby presented.
Disclosure of Invention
An object of the present invention is to provide a laser lift-off wafer apparatus and a laser lift-off wafer method, which can improve the above technical problems.
In a first aspect, an embodiment of the present application provides a laser lift-off wafer apparatus, which includes a mounting platform for mounting a crystal ingot, a laser emitter, a lens focusing assembly, a magnet, and a control system.
The laser emitter and the condenser lens assembly cooperate to focus the laser beam into the ingot to induce the ingot to generate a plasma; the magnet is used for providing a magnetic field, and the crystal ingot is positioned in the magnetic field so that the magnetic field can regulate and control the motion state of the plasma; the control system can obtain the characteristic parameters of the plasma in real time and regulate and control the magnetic field where the crystal ingot is located in real time according to the characteristic parameters, wherein the characteristic parameters of the plasma comprise the density of the plasma and the temperature of the plasma.
In the implementation process, in the process of obtaining the wafer by peeling the crystal ingot with the laser, the plasma induced by the laser is regulated and controlled through the magnetic field, and the motion process of the plasma in the crystal ingot is changed in real time to carry out secondary processing on the modified layer, so that the problem that the high-temperature and high-density plasma is difficult to control in the existing laser processing process is solved, the existing laser processing defects are reduced or even eliminated, the adverse effect of the plasma on the peeling surface of the wafer is converted into a beneficial effect, the secondary processing of the processing surface of the wafer is realized, and the quality and the efficiency of the wafer peeling processing are greatly improved.
In one possible embodiment, the magnet comprises an electromagnet, and the control system regulates the magnetic field in which the ingot is positioned by controlling the relative position of the electromagnet and the mounting platform, the current power of the electromagnet, and the current type.
In the implementation process, the direction, strength and the like of the magnetic field are regulated and controlled through the relative position of the electromagnet and the mounting platform, the current power of the electromagnet and the change of the current type, so that the motion process of the plasma is regulated and controlled, the processing controllability is improved, the thermal influence is reduced, and the plasma density and the plasma temperature for the induction effect of the magnetic field on the plasma are used as specific parameters to be fed back to the control system.
Optionally, the current power of the electromagnet is regulated within a range of 1-20W, and the current type of the electromagnet is direct current or alternating current, wherein the alternating current frequency is regulated within a range of 1-100 Hz.
In one possible embodiment, the magnets are ring-shaped or U-shaped, the magnets being circumferentially disposed about the ingot with a gap therebetween.
In the implementation process, the gap is arranged, so that the magnet is not contacted with the mounting platform, and meanwhile, the magnet and the mounting platform are convenient to move or rotate relatively, so that the relative position is regulated and controlled, and the magnetic field where the crystal ingot is located is adjusted.
In one possible embodiment, the focusing lens assembly includes a beam expander lens and a focusing lens; the beam expanding lens receives the laser beam emitted by the laser emitter and sends the laser beam to the focusing lens, and the focusing lens focuses the received laser beam in the crystal ingot. In the implementation process, the diameter and the divergence angle of the laser beam are changed through the beam expander, and the focusing effect is better through the matching with the focusing lens.
Optionally, the focusing lens assembly includes a reflector, the reflector is disposed between the beam expander and the focusing lens, and the reflector is configured to receive and reflect the laser beam sent from the beam expander to the light incident surface of the focusing lens. In the implementation process, the transmission path of the laser beam is effectively changed through the arrangement of the reflecting mirror.
In one possible embodiment, the laser wafer stripping device comprises a spectrometer, wherein the spectrometer is connected with a control system, the spectrometer is used for collecting the intensity of the plasma in real time and feeding the intensity back to the control system, and the control system converts the obtained intensity of the plasma into the density of the plasma and the temperature of the plasma in real time.
In one possible embodiment, the laser lift-off wafer apparatus includes an imaging system for monitoring and obtaining images of the modified layer in real time.
In the implementation process, the quality and the efficiency of the wafer peeling processing are greatly improved through the spectrometer and the image system.
In a possible embodiment, the laser wafer stripping device further comprises a control module arranged on the mounting platform and/or the magnet, the control module is connected with the control system, and the control module is used for controlling the relative translation, lifting and/or rotation of the mounting platform and the electromagnet.
In the implementation process, the mounting platform and the magnet are driven to translate, lift and/or rotate relatively by the driving system so as to change the relative position between the mounting platform and the magnet, and further change the magnetic field of the crystal ingot.
In one possible embodiment, the predetermined machining path comprises a straight path and/or a curved path.
In the implementation process, the preset machining track can be set according to actual requirements, and different machining requirements are met.
In a second aspect, an embodiment of the present application provides a method for laser lift-off of a wafer, including:
the crystal ingot is installed and fixed on the installation platform of the laser stripping wafer device provided by the first aspect of the application.
The crystal ingot is positioned in the magnetic field, the laser beam is focused on a target focusing plane in the crystal ingot and induces the crystal ingot to generate plasma, the laser beam moves along a preset processing track to form a modified layer in the crystal ingot, and the control system regulates and controls the magnetic field of the crystal ingot in real time according to the characteristic parameters of the plasma obtained in real time to control the motion state of the plasma.
The crystal ingot is positioned in the magnetic field, the laser beam is focused on a target focusing plane in the crystal ingot and induces the crystal ingot to generate plasma, the laser beam moves along a preset processing track to form a modified layer in the crystal ingot, and the control system regulates and controls the magnetic field in real time according to characteristic parameters of the plasma obtained in real time to control the motion state of the plasma.
In the implementation process, the control system regulates and controls the magnetic field according to the obtained characteristic parameters of the plasma, so as to control the motion state of the plasma, effectively solve the problem that high-temperature and high-density plasmas are difficult to control in the existing laser processing process, reduce or even eliminate the existing laser processing defects, and greatly improve the quality and efficiency of wafer peeling processing.
In one possible embodiment, the laser beam has a pulse width of 200fs to 10ns, a wavelength of 355nm to 1064nm, a power of 1W to 10W, a repetition frequency of 50kHz to 200kHz, and a scanning speed of 50mm/s to 200 mm/s.
In one possible embodiment, the thickness of the wafer is 200 μm to 600 μm.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 is a schematic diagram of a laser lift-off wafer apparatus 10 a;
FIG. 2 is a schematic diagram of an electromagnet according to some aspects of the present disclosure;
FIG. 3 is a schematic diagram of an electromagnet according to further embodiments of the present disclosure;
fig. 4 is a schematic structural view of the electromagnet according to the present embodiment;
FIG. 5 is a schematic diagram of electromagnetically regulating the state of a plasma;
FIG. 6 is a schematic structural diagram of a laser lift-off wafer apparatus 10 b;
fig. 7 is a schematic view of the state of the plasma.
Icon: 10 a-a laser lift-off wafer device; 10 b-laser lift-off wafer device; 100-mounting a platform; 101-a bearing surface; 110-a laser emitter; 111-a laser beam; 121-a beam expander; 123-a focusing mirror; 1231-focal point; 125-mirror; 130-an electromagnet; 20-ingot; 200-target focal plane; 210 — modifying the layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Examples
Referring to fig. 1, a laser lift-off wafer apparatus 10a includes: mounting platform 100, laser emitter 110, a lens assembly, a magnet, and a control system (not shown).
The laser emitter 110 is used for emitting a laser beam, and the laser emitter 110 is specifically, for example, a femtosecond laser, and the like, and is not limited herein.
The condenser assembly is used for receiving the laser beam 111 emitted by the laser emitter 110 and focusing the received laser beam 111 into the crystal ingot 20 to induce the crystal ingot 20 to generate plasma.
The focusing assembly comprises a beam expander 121 and a focusing mirror 123, the beam expander 121 receives the laser beam 111 emitted by the laser emitter 110 and transmits the laser beam 111 to the focusing mirror 123, the focusing mirror 123 focuses the received laser beam 111 in the crystal ingot 20, and a focal point 1231 of the focusing mirror 123 is located on the target focusing plane 200 of the crystal ingot 20. The diameter and the divergence angle of the laser beam are changed by the beam expander 121, and the focusing effect is better by matching with the focusing mirror 123. Under the above conditions, when the laser transmitter 110 needs to be vertically disposed and the laser transmitting port needs to be downwardly opposed to the ingot 20.
In this embodiment, the lens focusing assembly further includes a reflector 125, the reflector 125 is disposed between the beam expander 121 and the focusing mirror 123, and the reflector 125 is configured to receive and reflect the laser beam 111 sent from the beam expander 121 to the light incident surface of the focusing mirror 123. That is, the transmission path of the optical path is changed by the arrangement of the reflecting mirror 125, and in this case, the laser transmitter 110 may be horizontally arranged.
The number of the reflecting mirrors 125 may be one or more, specifically, for example, two or three, and may be set according to actual requirements.
The laser beam 111 is moved along a predetermined processing trajectory to form the modified layer 210 within the ingot 20, optionally in a manner that the laser beam 111 is moved along the predetermined processing trajectory including: the laser emitter 110 is provided with a moving module (not shown), the control system is connected with the moving module to control the laser emitter 110 to move along a preset processing track, or the mounting platform 100 is provided with a moving module, the control system is connected with the moving module to control the mounting platform 100 to move along a preset processing track, or both the laser emitter 110 and the mounting platform 100 are provided with a moving module, the control system is respectively connected with the two moving modules to independently control the laser emitter 110 and the mounting platform 100 to move relatively so that the laser beam 111 moves along a preset processing track, and the specific setting mode refers to the related art, which is not limited herein.
The preset processing track includes a straight line track and/or a curved line track, for example, the preset processing track is a straight line, or a curved line, or a combination of a straight line and a curved line, and those skilled in the art can make relevant adjustments according to actual needs.
Magnets are used to provide a magnetic field, wherein the magnets include magnets as well as electromagnets 130. The ingot 20 is positioned in a magnetic field to enable the magnetic field to manipulate the motion of the plasma. Here, the motion state refers to a motion direction of the plasma.
The control system can obtain the characteristic parameters of the plasma in real time, and can regulate and control the magnetic field of the crystal ingot 20 in real time according to the characteristic parameters so as to change the motion process of the laser-induced plasma in the crystal ingot 20 in real time to carry out secondary processing on the modified layer 210, so that the adverse effect of the plasma on the wafer peeling surface is converted into a beneficial effect, the secondary processing of the processing surface of the wafer is realized, and the quality and the efficiency of the peeling processing of the wafer from the crystal ingot 20 are greatly improved. Wherein the characteristic parameters of the plasma include the density of the plasma and the temperature of the plasma.
The control system is, for example, a PC, which has a display screen and a keyboard, can input and output related instructions, and can visually present related data on the display screen.
The control system can directly acquire the characteristic parameters or directly acquire related parameters such as the intensity of the plasma, and then obtain the density of the plasma and the temperature of the plasma according to conversion.
Specifically, the laser wafer stripping device comprises a spectrometer and an imaging system.
The spectrometer is connected with the control system, and is used for acquiring the intensity of the plasma in real time and feeding the intensity back to the control system, and the control system converts the acquired intensity of the plasma into the density of the plasma and the temperature of the plasma in real time based on principles such as ohm's law, Boltzmann equation and the like and by combining with the material characteristics of the crystal ingot 20 (the specific manner can refer to the related art, and is not described herein). The imaging system is a CCD imaging system for monitoring and acquiring images of the modified layer 210 in real time to visually observe the processing morphology of the ingot 20.
In some embodiments provided herein, the magnet is a magnet, and the control system controls the magnetic field of the ingot 20 by controlling the relative position of the magnet and the mounting platform 100, so that the plasma does not increase the thickness of the modified layer and secondary processing of the ingot peeling surface can be achieved.
In this embodiment, the magnet is an electromagnet 130, and the control system is connected to the electromagnet 130, and the control system controls the magnetic field of the ingot 20 by controlling the relative position of the electromagnet 130 and the mounting platform 100, the current power of the electromagnet 130, and the current type. The current power of the electromagnet 130 is adjusted within a range of 1-20W, the current type is direct current or alternating current, and the alternating current frequency is adjusted within a range of 1-100 Hz.
The relative position of the electromagnet 130 and the mounting platform 100, the current power of the electromagnet 130 and the current type regulate and control the magnetic field of the crystal ingot 20, so that the plasma does not cause the increase of the thickness of the modified layer and the secondary processing of the crystal ingot peeling surface can be realized.
The laser lift-off wafer apparatus 10a includes a control module (not shown) disposed on the mounting platform 100 and/or the magnet, the control module is connected to the control system, and the control module is configured to control the mounting platform 100 and the magnet to translate, lift and/or rotate relatively, so as to adjust the relative position between the ingot and the magnet. It should be noted that the control module may be only provided on the mounting platform 100 or the magnet, or both the mounting platform 100 and the magnet may be provided with the control module.
In this embodiment, the mounting platform 100 and the electromagnet 130 are both provided with a control module, and the control module is used for controlling the relative translation, lifting and rotation of the mounting platform 100 and the electromagnet 130.
For convenience of description, a control module provided on the mounting platform 100 is used as a first control module, and a control module provided on the electromagnet 130 is used as a second control module, where the first control module and the second control module exist independently and are respectively connected to the control system, and the first control module is configured to control the mounting platform 100 to translate along the X direction and the Y direction, lift along the Z direction, and rotate along the Z direction (where the X direction, the Y direction, and the Z direction are perpendicular to each other, and the Z direction coincides with a central line of the mounting platform 100). The second control module is used for controlling the electromagnet 130 to move horizontally in the X direction and the Y direction, lift in the Z direction and rotate in the Z direction. The specific structure capable of achieving the above translation in the X direction and the Y direction, the lifting in the Z direction, and the rotation in the Z direction has various structures, which are not limited herein, and reference may be made to related technologies as long as the above functions are achieved.
In an actual using process, the control system may control the position of the electromagnet 130 to be unchanged through the second control module, and the control system controls the mounting platform 100 to relatively translate, lift, and rotate with respect to the electromagnet 130 through the first control module, and similarly, the control system may control the position of the mounting platform 100 to be unchanged through the first control module, and the control system controls the electromagnet 130 to relatively translate, lift, and rotate with respect to the mounting platform 100 through the second control module, or the control system synchronously moves the mounting platform 100 and the electromagnet 130 through the second control module and the first control module, so that the electromagnet 130 relatively translates, lifts, and rotates with respect to the mounting platform 100.
Wherein the electromagnet 130 is provided in the circumferential direction of the ingot 20 mounted on the mounting platform 100 with a gap from the ingot 20. The relative movement of electromagnet 130 and ingot 20 is facilitated by the provision of the gap.
Alternatively, referring to fig. 2, in some examples shown in the present application, the electromagnets 130 are two separate bar-shaped electromagnet units, wherein two bar-shaped electromagnet units are respectively disposed around two opposite sides of the mounting platform 100 and symmetrically arranged along the center line of the mounting platform 100, and the N pole of one of the two bar-shaped electromagnet units is disposed opposite to the S pole of the other electromagnet unit, and the electromagnets 130 have a gap with the ingot placed on the mounting platform 100.
Alternatively, in another illustrated example, the electromagnet 130 is U-shaped, the U-shaped electromagnet 130 surrounds the circumference of the ingot with a gap from the mounting platform 100, wherein the N and S poles of the U-shaped electromagnet 130 are symmetrically arranged along the center line of the mounting platform 100.
Alternatively, the electromagnet 130 is ring-shaped, and the electromagnet 130 is arranged around the ingot 20 with a gap between the inner edge of the electromagnet 130 and the ingot 20. In the present application, the ring shape includes, but is not limited to, a circular ring, and also includes a square ring, a diamond ring, a hexagonal ring, an octagonal ring, and the like.
Referring to fig. 3, in another embodiment of the present application, the electromagnet 130 is in the shape of a square ring.
Referring to FIG. 4, in the present embodiment, the electromagnet 130 is a circular ring, wherein the N pole and S pole of the electromagnet 130 are located at +/-X and-/+ X directions of the electromagnet 130, respectively.
The application provides a method for peeling a wafer by laser, which comprises the following steps:
the ingot 20 is mounted and fixed to the mounting platform 100 of the laser lift-off wafer apparatus 10a provided in the present embodiment.
And (3) turning on the laser and the electromagnet 130, enabling the crystal ingot 20 to be positioned in the magnetic field, enabling the laser beam 111 to be focused on a target focusing plane 200 in the crystal ingot 20, inducing the crystal ingot 20 to generate plasma, and controlling the laser beam 111 to move along a preset processing track so as to form a modified layer 210 with the thickness L inside the crystal ingot 20 by the control system.
The control system adjusts and controls the electromagnet 130 in real time according to the characteristic parameters of the plasma obtained in real time to form the modified layer 210 in the ingot 20 on the target focal plane 200, for example: according to the motion track of the laser beam 111, since the N pole and the S pole of the electromagnet 130 are respectively positioned in +/-X and-/+ X directions of the electromagnet 130, the electromagnet 130 and the crystal ingot 20 are relatively translated, the plasma in the laser action area tends to move in the X direction under the action of the magnetic induction lines, the motion in the Y direction is compressed, and the state of electromagnetically regulating the plasma is shown in FIG. 5. The plasma will act only on the region of the modified layer 210 having the thickness L to perform the secondary processing on the modified layer 210. In the laser processing process, the monitoring system collects the characteristic parameters of the plasma in real time so as to feed back the induction action of the adjusting electromagnet 130 on the plasma and monitor the change state of the modified layer 210 with the thickness L of the crystal ingot 20. When modified layer 210 penetrates the interior of ingot 20, laser and electromagnet 130 are turned off, and the wafer is peeled from ingot 20.
Wherein, the pulse width of the laser beam 111 is 200 fs-10 ns, the wavelength is 355 nm-1064 nm, the power is 1W-10W, the repetition frequency is 50 kHz-200 kHz, and the scanning speed is 50 mm/s-200 mm/s.
The thickness of the wafer is 200 μm to 600 μm, that is, the ingot 20 is peeled to a thickness of 200 μm to 600 μm.
Meanwhile, a comparison example is provided to compare with the laser lift-off wafer apparatus 10a and the laser lift-off wafer method provided in the present application, wherein, referring to fig. 6, the laser lift-off wafer apparatus 10b of the comparison example is different from the laser lift-off wafer apparatus 10a provided in the present embodiment only in that the electromagnet 130 is not provided, and specifically, the laser lift-off wafer method includes:
taking an ingot 20 to be stripped, installing and fixing the ingot on an installation platform 100, starting a laser, focusing the laser on a target focusing plane 200 in the ingot 20 according to the thickness of a wafer to be processed, inducing the ingot 20 to generate plasma, and moving a laser beam 111 along a preset processing track to form a modified layer 210 with the thickness L in the ingot 20. Without the action of the electromagnet 130, the state of the plasma is shown in fig. 7, and the plasma induced by the laser beam 111 inside the ingot 20 cannot be regulated. At this time, the plasma in the laser action region willMoving to the four sides, the thickness of the formed modified layer 210 will increase to L1I.e. with L1Is > L. It can be seen that increasing the thickness of the modified layer 210 not only expands the range of lasing action, but also results in more material loss. For an ingot 20 of the same thickness, the number of wafers obtained will also be reduced, increasing material processing costs.
In conclusion, the laser wafer stripping device and the laser wafer stripping method have the advantages that the movement process of the plasma in the crystal ingot is changed in real time through the introduction of the magnetic field and the regulation and control of the plasma induced by the laser through the magnetic field so as to carry out secondary processing on the modified layer, the problem that the high-temperature and high-density plasma is difficult to control in the existing laser processing process is solved, the existing laser processing defects are reduced or even eliminated, the adverse effect of the plasma on the wafer stripping surface is converted into a beneficial effect, the secondary processing of the processed surface of the wafer is realized, and the quality and the efficiency of the wafer stripping processing are greatly improved.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A laser lift-off wafer apparatus, comprising:
a mounting platform for mounting the ingot;
a laser emitter and a condenser assembly cooperating to focus a laser beam into the ingot to induce the ingot to generate a plasma, the laser beam being movable along a predetermined processing trajectory to form a modified layer within the ingot;
a magnet to provide a magnetic field, the ingot being positioned in the magnetic field to enable the magnetic field to regulate a state of motion of the plasma; and
and the control system can obtain the characteristic parameters of the plasma in real time and regulate and control the magnetic field where the crystal ingot is located in real time according to the characteristic parameters, wherein the characteristic parameters of the plasma comprise the density of the plasma and the temperature of the plasma.
2. The laser lift-off wafer apparatus of claim 1, wherein the magnet comprises an electromagnet, and the control system regulates the magnetic field in which the ingot is located by controlling a relative position of the electromagnet and the mounting platform, a current power of the electromagnet, and a current type;
optionally, the adjustment range of the current power of the electromagnet is 1-20W, the current type of the electromagnet is direct current or alternating current, and the adjustment range of the alternating current frequency is 1-100 Hz.
3. The laser lift-off wafer device of claim 1, wherein the magnet is ring-shaped or U-shaped, the magnet is arranged around the circumference of the ingot with a gap therebetween.
4. The device for laser lift-off of wafers of claim 1, wherein the device for laser lift-off of wafers comprises a spectrometer, the spectrometer is connected with a control system, the spectrometer is used for collecting the intensity of plasma in real time and feeding the intensity back to the control system, and the control system converts the obtained intensity of plasma into the density of plasma and the temperature of plasma in real time.
5. The laser lift off wafer apparatus of claim 1, wherein the laser lift off wafer apparatus comprises an imaging system for monitoring and obtaining images of the modified layer in real time.
6. The laser lift off wafer apparatus of claim 1, further comprising a control module disposed on the mounting platform and/or the magnet, wherein the control module is connected to the control system, and the control module is configured to control the mounting platform and the magnet to translate, lift and/or rotate relatively.
7. The apparatus of claim 1, wherein the predetermined processing path comprises a straight path and/or a curved path.
8. A method for laser lift-off of a wafer, comprising:
mounting an ingot to the mounting platform of the laser lift-off wafer apparatus of any of claims 1 to 7;
the crystal ingot is positioned in the magnetic field, the laser beam is focused on a target focusing plane in the crystal ingot and induces the crystal ingot to generate plasma, the laser beam moves along a preset processing track to form a modified layer in the crystal ingot, and the control system regulates and controls the magnetic field of the crystal ingot in real time according to characteristic parameters of the plasma obtained in real time to control the motion state of the plasma.
9. The method of claim 8, wherein the laser beam has a pulse width of 200fs to 10ns, a wavelength of 355nm to 1064nm, a power of 1W to 10W, a repetition frequency of 50kHz to 200kHz, and a scanning speed of 50mm/s to 200 mm/s.
10. The method of claim 8, wherein the wafer has a thickness of 200 μm to 600 μm.
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