Cutting device using Bezier beam

Abstract

The utility model discloses a cutting device utilizing a Bezier beam, which comprises at least two laser processing units, a control unit and a clamping and moving unit, the clamping and moving unit is used for clamping a material to be cut and providing translation in X-Y-Z directions and rotation of the material to be cut, and the cutting device is characterized in that at least two laser processing units are arranged; the laser processing units output non-diffraction Bessel beams, the spot diameter of filiform light spots formed by focusing the Bessel beams is 20-100 micrometers, the non-diffraction distance of the Bessel beams is 15-300 millimeters, and the Bessel beams output by the laser processing units are located in different circumferential directions of the cutting plane respectively. The Bessel beam is adopted, thick materials can be directly ablated and cut, meanwhile, at least two laser processing units are arranged, a plurality of cutting planes can be synchronously cut, or the position of one cutting plane can be simultaneously cut, and the cutting speed is greatly improved.

Description

Technical Field

[0001] The utility model relates to a device for processing materials by using laser, in particular to a device for cutting materials by using Bessel beam, especially a cutting device adopting a material removal method. Background Art

[0002] The cutting of brittle and hard materials has always been the focus of research in the field of material processing. Especially when the workpiece to be processed has a certain thickness, the cutting is more difficult. In semiconductor materials, there appear the second-generation semiconductors such as gallium arsenide (GaAs) and indium phosphide (InP), and the third-generation semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) as the substrates of core devices, as well as the fourth-generation ultra-wide bandgap semiconductor materials such as diamond and gallium oxide, most of which are brittle and hard materials.

[0003] Traditionally, the cutting of brittle and hard materials relies on mechanical means such as ring band saws and diamond wire saws. However, in the face of materials such as silicon carbide (SiC) and diamond with a Mohs hardness exceeding 9 and extremely high brittleness, these traditional methods seem inadequate. The high hardness and high brittleness characteristics of SiC and diamond not only require the use of expensive diamond as the cutting medium but also result in significant cutting losses. At the same time, the cutting takes a long time. It takes more than 80 hours to cut an 8-inch silicon carbide ingot with a diamond wire. To solve this problem, laser cutting technology emerges as an innovative solution.

[0004] Conventional laser cutting uses a Gaussian laser beam. Due to the large cone angle of the Gaussian beam, if the thickness of the workpiece to be cut is large, it will cause large cutting losses on the cross section. For example, when using a Gaussian laser to directly cut and separate from the side of the ingot, for an ingot with a diameter greater than 4 inches (100 mm), the cutting loss is expected to be greater than 2 mm. Such a large loss is unacceptable for processing enterprises. Therefore, in the prior art, for semiconductor ingots, direct material removal cutting is not adopted. Instead, the laser is incident from a direction perpendicular to the cutting surface, so that the laser beam is focused at the cutting surface, the part of the cutting surface is modified, and then thermal decomposition separation is carried out by methods such as heating, mechanical or chemical methods. However, after this process, the upper surface of the ingot is affected by the modified layer and needs to be ground and polished again for the next layer of modification, otherwise the laser is difficult to penetrate.

[0005] Although there are various improvements to laser cutting, however, the overall solution idea of the prior art is that the laser beam is incident from the main surface of the ingot (close to perpendicular to the cutting surface) to form a modified layer and then carry out cracking. However, the modified separation layer is usually relatively thick, and subsequent external force assistance is required for separation, which will lead to a decrease in the yield rate.

[0006] Bessel beams have the characteristic of non-diffracting over long distances and have currently been publicly used for the cutting of ultra-thick glass, especially hidden cutting. For example, Chinese Patent Application for Invention CN 118145881 A and Chinese Invention Patent CN 114178712 B both disclose their use in glass cutting. Through a surface with very good light transmittance, relying on extremely high power (high peak power) and energy density, the chemical bonds of the material are broken to achieve cutting, and there is no material removal process during cutting. Therefore, this method requires extremely high power density and energy density. In addition, the incident surface of the material needs to have a very high transmittance. At the same time, it is necessary to control the diameter of the focused filamentous light spot. For example, it is generally considered that it needs to be no more than 5 microns, but this also limits the length of the filamentous light spot at the same time. This is also the reason why CN 118145881 A developed a layer-by-layer cutting method.

[0007] Therefore, when laser cutting brittle and hard materials, it is necessary to seek a new cutting device. Summary of the Invention

[0008] The invention object of the present utility model is to provide a cutting device using Bessel beams, which can improve the cutting speed without the need for chipping, so as to be used for the cutting of brittle and hard materials with a relatively large thickness.

[0009] To achieve the above invention object, the technical solution adopted by the present utility model is: a cutting device using Bessel beams, including a laser processing unit, a control unit, and a clamping and moving unit. The control unit is connected to control the laser processing unit and the clamping and moving unit. The clamping and moving unit clamps the material to be cut and provides translation in the X-Y-Z directions and rotation of the material to be cut. There are at least 2 laser processing units. The laser processing units output non-diffracting Bessel beams. The spot diameter of the filamentous light spot formed by focusing the Bessel beams is 20 - 100 microns, and the non-diffracting distance of the Bessel beams is 15 - 300 millimeters. The Bessel beams output by each laser processing unit are respectively located in different circumferential directions of the cutting plane.

[0010] In a preferred technical solution, there are 3 laser processing units, and the Bessel beams output by each laser processing unit are evenly distributed along the circumference of the cutting plane.

[0011] In a preferred technical solution, the included angle between the Bessel beam and the surface of the material at the cutting processing position is α, and α is less than 80°, so that the projected shape of the Bessel beam at the cutting position is an ellipse, and the waist radius of the Bessel beam is w, and the major axis of its elliptical projection is greater than 2.03w.

[0012] In a preferred technical solution, the spot diameter of the filamentous light spot formed by focusing the Bessel beams is 30 - 100 microns, and the non-diffracting distance of the Bessel beams is 50 - 300 millimeters.

[0013] In the above technical solution, each of the laser processing units includes a laser and a Bessel component. The laser outputs a Gaussian beam, which is converted by the Bessel component to obtain the non-diffracting Bessel beam.

[0014] In the above technical solution, the Bessel component includes a combined axicon lens for regulating the light field to generate a non-diffracting Bessel beam. A focusing lens group is provided in the outgoing direction of the Bessel beam for regulating the diameter and focal depth of the Bessel beam.

[0015] Among them, the combined axicon lens is a combined axicon of the same material with different cone base angles.

[0016] Alternatively, the combined axicon lens is a combined axicon of the same cone base angle with different materials.

[0017] In a further technical solution, a workpiece processing unit is provided, which includes a motor and a mechanical claw driven by the motor. The mechanical claw is used to pick up the cutting piece and fix the remaining material body each time the laser cutting is completed, and withdraws after the clamping and rotating device fixes the remaining body again.

[0018] In a further technical solution, the material to be cut is cylindrical, and the cutting plane is a plane perpendicular to the cylindrical axis of symmetry; the clamping and moving unit has a rotational degree of freedom that enables the material to be cut to rotate about the cylindrical axis of symmetry; the filamentous light spot feeds from the outer periphery of the cylinder inward.

[0019] Due to the application of the above technical solution, the present utility model has the following advantages compared with the prior art:

[0020] 1. The present utility model adopts a Bessel beam, which can directly ablate and cut thicker materials without the need for cutting in the way of modification and chipping as in the prior art. At the same time, by setting at least two laser processing units, multiple cutting planes can be cut synchronously, or the position of a single cutting plane can be cut simultaneously, greatly improving the cutting speed.

[0021] 2. The non-diffracting distance of the Bessel beam of the present utility model is 50 to 150 millimeters, which can conveniently cut thicker materials. The material removal method can be adopted to achieve a cutting width of less than 0.1 mm under the premise that the light spot diameter is one order of magnitude larger than that of the prior art, which can reduce cutting loss and improve processing efficiency and accuracy.

[0022] 3. The utility model is particularly applicable to the separation of semiconductor ingots. It adopts a cutting method in which a long-distance non-diffracting Bessel beam is incident from the side of the ingot. Compared with a Gaussian spot, there is no processing cone angle, reducing material loss. Compared with laser modification separation, the separation layer width is smaller, and the next slicing can be directly carried out after separation without re-grinding and polishing, significantly improving the processing efficiency. In addition, there is no need to introduce a separation device, and the operation is extremely simple.

[0023] 4. By inclining the Bessel beam at a certain angle for incidence, under the premise of ensuring the laser energy, the heat action area is wider, achieving a higher volume removal efficiency, and at the same time, it is more convenient to remove the solid-liquid particles generated by ablation. Brief Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of a device for removing materials using a Bessel beam in an embodiment of the utility model.

[0025] Figure 2 It is a schematic diagram of the generation principle of the Bessel beam of the utility model.

[0026] Figure 3 It is a schematic diagram of the first combined axicon in the embodiment.

[0027] Figure 4 It is a schematic diagram of the second combined axicon in the embodiment.

[0028] Figure 5 It is a schematic structural diagram of the clamping and moving unit in the embodiment.

[0029] Figure 6 It is a schematic layout diagram of the laser processing unit in another embodiment of the utility model.

[0030] Wherein: 1. Control unit; 2. Laser processing unit; 3. Clamping and moving unit; 4. Workpiece processing unit; 5. Material to be cut; 6. Bessel beam; 21. Laser; 22. Bessel processing head; 211. Combined axicon; 212. Focusing lens group; 2111. Positive axicon; 2112. Negative axicon; 31. Clamping and rotating device; 32. X-Y-Z three-way moving device Detailed Embodiment

[0031] The following further describes the utility model in conjunction with the drawings and embodiments:

[0032] Embodiment 1: As Figure 1 shown, a cutting device using a Bessel beam includes: a control unit 1, a laser processing unit 2 for cutting materials, a clamping and moving unit 3 for fixing and moving materials, and a workpiece processing unit 4.

[0033] Among them, the clamping and moving unit 3 has a clamping and rotating device 31 for controlling the material to be cut and an X-Y-Z three-way moving device 32.

[0034] Figure 2 It is a schematic diagram of the generation principle of Bessel beam. The laser processing unit 2 includes a laser 21 and a Bessel processing head 22. The Bessel processing head 22 has a combined axicon 211 and a focusing lens group 212. In this embodiment, 2 laser processing units are provided, and the emitted beams of the 2 laser processing units are respectively located at different circumferential positions of the material to be cut, and the distance between the two planes where the two beams are located is equal to the thickness of the slice to be cut, so that the cutting of two surfaces can be carried out synchronously at one time.

[0035] In this embodiment, the average power of the laser 21 is 75W, the wavelength of the output laser beam is 1064nm, the laser beam output by the laser 21 is pulsed output, the output pulse width is 100ps, the repetition frequency is 500kHz, and the single pulse energy is 150μJ. The output beam is a Gaussian beam, and the beam waist radius w0 is 10mm.

[0036] See Figure 3 , in this embodiment, the combined axicon 211 adopts a combined axicon with the same cone surface base angle and different materials. Among them, the refractive index n1 of the positive axicon 2111 material is 1.545, the refractive index n2 of the negative axicon 2112 material is 1.534, then the equivalent refractive index n1 - n2 + 1 is 1.011; and the cone surface base angles of the positive and negative axicons are both 1°. In the focusing lens group 212, the focal length f1 of the first lens is 110mm, and the focal length f2 of the second lens is 5mm.

[0037] In this embodiment, the beam waist radius of the Bessel beam obtained by the combined axicon mirror is 20μm (the formed spot diameter is slightly larger than 40μm), and the non-diffraction distance is 107mm.

[0038] See Figure 5 , it is a schematic diagram of the structure of the clamping and rotating device 31. The clamping and rotating device 31 is used to drive the material to be cut to move and rotate, and in combination with the X-Y-Z three-way moving device, the spot moves relative to the material to be cut along a preset trajectory.

[0039] In addition, a scheme of adding a three-dimensional moving device to the laser processing unit can also be adopted to realize the relative movement of the spot and the material to be cut to achieve laser cutting.

[0040] The device of this embodiment is used to cut an 8-inch silicon carbide semiconductor ingot with a thickness of 2cm.

[0041] The semiconductor ingot is irradiated from the side with the Bessel laser beam.

[0042] A galvanometer scanner can be set on the Bessel processing head 22. The incident angle α (the cross angle between the laser beam and the tangent of the incident point on the ingot surface) is adjusted to 40° through the galvanometer scanner. The X-Y-Z three-axis movement of the material to be processed is realized through the clamping and moving unit to adjust the cutting position and ensure that the cutting thickness meets the requirements. The rotational angular velocity is set to 0.5 rad / s. As the material to be processed rotates, the laser removes the material, thereby realizing the separation of the wafer from the ingot. After all the wafers are cut and separated, subsequent operations such as grinding and polishing are uniformly performed on the wafers, and the flatness meets the requirements after testing.

[0043] Due to the existence of the incident angle α, the projected shape of the Bessel beam at the cutting position is an ellipse. Embodiment 2

[0044] Cut a 2-inch diamond semiconductor ingot with a thickness of 1 mm.

[0045] The average power of the laser 21 is 50 W, the wavelength of the output laser beam is 532 nm, the laser beam output by the laser 21 is pulsed output, the output pulse width is 2 ns, the repetition frequency is 200 kHz, and the single pulse energy is 250 μJ.

[0046] The waist radius w0 of the Gaussian beam output by the laser 21 is 10 mm.

[0047] In this embodiment, as Figure 4 shown, the combined axicon lens uses a combined axicon of the same material and different cone base angles. Among them, the refractive index n of the positive and negative axicon materials is 1.4, the cone base angle γ1 of the positive axicon 2111 is 5°, and the cone base angle γ2 of the negative axicon 2112 is 4.9°.

[0048] The focal lengths of the two lenses in the focusing lens group are: f1 is 120 mm and f2 is 5 mm.

[0049] The waist radius of the obtained Bessel beam is 17 μm, and the non-diffracting distance is 25 mm.

[0050] Use this Bessel laser beam to perform side incidence on the semiconductor ingot. The incident angle α (the cross angle between the laser beam and the tangent of the incident point on the ingot surface) is adjusted to 30° through the galvanometer scanner. The ingot is moved through the X-Y-Z three-axis movement of the clamping and moving unit to ensure that the cutting thickness meets the requirements. The rotational angular velocity is set to 0.2 rad / s. As the material to be cut rotates, the laser removes the material, thereby realizing the separation of the wafer from the ingot. After all the wafers are cut and separated, subsequent operations such as grinding and polishing are uniformly performed on the wafers, and the flatness meets the requirements at the same time.

[0051] In this embodiment, to accelerate the processing speed, three laser processing units are set. See Appendix Figure 6As shown in the figure, it is a schematic diagram of the incident direction of the Bessel beam. The material to be cut 5 is a cylindrical ingot. When observing from one end of the ingot, it can be seen from the figure that the Bessel beams 6 output by the three laser processing units are respectively irradiated at different circumferential positions on the cutting plane, and the angle between them is 120°. For each Bessel beam, the angle between its irradiation direction and the material surface at the cutting position is α, and α is less than 80°.

[0052] The three laser processing units in this embodiment can simultaneously process the same cutting plane, increasing the processing speed to nearly 3 times. They can also be staggered from each other to process different cutting planes respectively, so that 3 slices can be obtained in one processing.

Claims

1. A cutting device using a Bessel beam, comprising a laser processing unit, a control unit and a clamping and moving unit, wherein the control unit is connected to control the laser processing unit and the clamping and moving unit, and the clamping and moving unit clamps the material to be cut and provides translation in the X-Y-Z directions and rotation of the material to be cut, characterized in that: There are at least 2 of the laser processing units, and the laser processing units output non-diffracting Bessel beams. The spot diameter of the filamentous spot formed by focusing the Bessel beam is 20 to 100 microns, and the non-diffracting distance of the Bessel beam is 15 to 300 millimeters. The Bessel beams output by each laser processing unit are respectively in different circumferential directions of the cutting plane.

2. The cutting device using a Bessel beam according to claim 1, characterized in that: There are 3 of the laser processing units, and the Bessel beams output by each laser processing unit are evenly distributed along the circumference of the cutting plane.

3. The cutting device using a Bessel beam according to claim 1, characterized in that: The angle between the Bessel beam and the material surface at the cutting position is α, and α is less than 80°, so that the projected shape of the Bessel beam at the cutting position is an ellipse. The waist radius of the Bessel beam is w, and the major axis of its elliptical projection is greater than 2.03w.

4. The cutting device using a Bessel beam according to claim 1, characterized in that: The spot diameter of the filamentous spot formed by focusing the Bessel beam is 30 to 100 microns, and the non-diffracting distance of the Bessel beam is 50 to 300 millimeters.

5. The cutting device using a Bessel beam according to claim 1, wherein: Each of the laser processing units includes a laser and a Bessel component. The laser outputs a Gaussian beam, and the non-diffracting Bessel beam is obtained through conversion by the Bessel component.

6. The cutting device using a Bessel beam according to claim 5, characterized in that: The Bessel component includes a combined axicon lens for regulating the light field to generate a non-diffracting Bessel beam. A focusing lens group is provided in the output direction of the Bessel beam for regulating the diameter and focal depth of the Bessel beam.

7. The cutting device using a Bessel beam according to claim 6, characterized in that: The combined axicon lens is a combined axicon of the same material with different cone base angles.

8. The cutting device using a Bessel beam according to claim 6, characterized in that: The combined axicon lens is a combined axicon of the same cone base angle with different materials.

9. The cutting device using a Bessel beam according to claim 1, characterized in that: There is a workpiece handling unit, which includes a motor and a mechanical claw driven by the motor. The mechanical claw is used to pick up the cutting piece and fix the remaining material body each time the laser cutting is completed, and withdraws after the clamping and rotating device fixes the remaining body again.

10. The cutting device using a Bessel beam according to claim 1, characterized in that: The material to be cut is cylindrical, and the cutting plane is a plane perpendicular to the cylindrical axis of symmetry; the clamping and moving unit has a rotational degree of freedom that enables the material to be cut to rotate around the cylindrical axis of symmetry. The filamentous spot feeds from the outer circumference of the cylinder inward.

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