Diamond fragmentation method and system for double-laser rotary machining

Abstract

The invention discloses a diamond fragmentation method and a diamond fragmentation system for double-laser rotary processing. The diamond fragmentation system comprises a first laser, a second laser, a first light path, a second light path and a sample table, the first laser emits first laser according to a first optical parameter, and the first laser irradiates the diamond on the sample table through a first light path in a first incident direction so as to generate modified points in the diamond; the second laser emits second laser according to a second optical parameter, the second laser irradiates the diamond on the sample table through a second light path in a second incident direction so as to act with the modified points in the diamond, and cracks are generated and expanded based on the modified points; wherein the first optical parameter is different from the second optical parameter, and the first incident direction and the second incident direction are parallel and opposite; the sample table has a rotating function and drives the diamond on the sample table to rotate to achieve double-laser rotating machining. According to the method, the high-quality diamond sheet can be efficiently obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser processing of diamond slicing, and specifically relates to a diamond slicing method and system for dual-laser rotary processing. Background Art

[0002] The existing growth processes of synthetic diamond mainly include the high-temperature high-pressure method and the chemical vapor deposition method (CVD). In the industrial field, the two growth technology paths correspond to different usage scenarios. The diamond obtained by the high-temperature high-pressure method is mainly used for tooling purposes such as sawing and grinding, while the diamond obtained by the CVD method is more suitable for functional purposes such as chips and electronic devices. As a semiconductor substrate, it has excellent electrical properties.

[0003] Diamond, being the material with the highest hardness in nature, is difficult to process by ordinary mechanical operations. Currently, to obtain diamond as a semiconductor substrate material, the bulk diamond grown by the CVD method is processed using a laser cutting process, that is, the diamond material is ablated by a high-power laser to cut the bulk and obtain thin slices. The problems of this method are as follows: First, when the laser directly ablates the diamond material, the effective depth of action is limited, which limits the size of the diamond that can be processed. Currently, the maximum size is 20 mm. In industrial applications, the existing diamond size has reached 8 inches, which is much larger than the size limited by laser ablation mentioned above. Second, when cutting the diamond material by laser ablation, the thickness loss of the cut will increase with the increase of the diamond size, seriously wasting the material. At the same time, the cut surface obtained by laser ablation cutting has an increasing tilt angle with the increase of the diamond size, which is not conducive to finally forming a flat thin slice.

[0004] For diamond substrates applied to the semiconductor industry, laser slicing is an effective processing method. Through optical design, the laser is focused inside the diamond. The power density of the laser at the focus is strong enough to interact with the diamond and cause material modification. The focused laser breaks the chemical bonds of the diamond lattice. After modification, the material changes from hard diamond to porous carbon material, and the carbon material can be easily mechanically separated by external force, thus realizing diamond slicing. By designing the path of the laser interacting with the diamond and the internal depth of material modification, the position and size of the diamond to be sliced can be effectively designed to obtain the expected thin slice.

[0005] The patent with publication number CN115555743A discloses a method for manufacturing a diamond substrate. This patent uses laser focusing to form processing marks at a certain depth below the upper surface of the material. These processing marks will cause the diamond material to crack along a specific direction and the cracks to extend, forming a cracking surface, thereby obtaining a diamond substrate. However, due to the extremely high hardness and strong brittleness of the diamond material, during the processing, it is extremely easy to cause out-of-control crack extension and fragmentation of the diamond material due to reasons such as energy changes in laser focusing and internal defects of the material.

[0006] In summary, for the preparation of diamond substrates applied in the semiconductor industry, laser slicing is an effective method, which can solve the problem of limited size encountered in the existing processing of diamonds. However, when using laser focusing alone to process diamonds, the instability is high and the problem of material fragmentation is likely to occur. Due to the existence of cleavage planes in diamonds - the (111) crystal plane, which is different from the growth plane (100) crystal plane, the material is extremely prone to fragmentation along the cleavage plane, forming an irregularly shaped structure, which is not conducive to subsequent use as a semiconductor substrate. Therefore, this processing method needs to be improved. Summary of the Invention

[0007] In view of the above, the object of the present invention is to provide a diamond slicing method and system for dual-laser rotation processing. By adopting the simultaneous processing mode of dual lasers, the interaction degree between the laser and the diamond can be effectively improved, the laser action effect can be accurately adjusted, and diamond thin slices can be obtained by processing and slicing. At the same time, by adopting a rotary processing path, the path planning method can be utilized to the greatest extent, and the efficiency can be greatly improved compared with the linear path.

[0008] To achieve the above object of the invention, a diamond slicing system for dual-laser rotation processing provided by an embodiment of the present invention includes:

[0009] It includes a first laser, a second laser, a first optical path, a second optical path, and a sample stage;

[0010] The first laser emits a first laser according to a first optical parameter, and the first laser irradiates the diamond on the sample stage through the first optical path in a first incident direction to generate modified particles inside the diamond;

[0011] The second laser emits a second laser according to a second optical parameter, and the second laser irradiates the diamond on the sample stage through the second optical path in a second incident direction to interact with the modified particles inside the diamond, generate cracks based on the modified particles and expand; wherein, the first optical parameter is different from the second optical parameter, and the first incident direction and the second incident direction are parallel and opposite;

[0012] The sample stage has a rotation function, and drives the diamond on the sample stage to rotate to realize dual-laser rotation processing.

[0013] Preferably, the first optical parameter includes a first pulse width, and the value range is 10 fs - 1 ns; the second optical parameter includes a second pulse width, and the value range is 0.1 ns - 100 ns, and the first pulse width is less than the second pulse width.

[0014] Preferably, the first optical parameter further includes a first wavelength, a first repetition frequency, and a first power density, and the second optical parameter further includes a second wavelength, a second repetition frequency, and a second power density;

[0015] Among them, the value ranges of the first wavelength and the second wavelength are 0.35 μm - 3 μm, the value ranges of the first repetition frequency and the second repetition frequency are 1 Hz - 1 MHz, and the value ranges of the first power density and the second power density are 0.1 W / cm 2 - 10 W / cm 2 .

[0016] Preferably, both the first optical path and the second optical path include an optical path component and a focusing objective along the laser transmission direction, and the size of the laser focusing spot is changed by adjusting the distance from the focusing objective to the diamond.

[0017] Preferably, the optical path component includes a mirror, a half-wave plate, a beam expander group, a lens group, and another mirror along the laser transmission direction.

[0018] Preferably, when the size of the laser focusing spot formed by the second laser on the diamond is larger than the size of the laser focusing spot formed by the first laser on the diamond, the second power density included in the second optical parameter is less than the first power density included in the first optical parameter.

[0019] Preferably, the sample stage includes a base, a bracket arranged on the base, a telescopic rod arranged on the bracket, a clamp connected to the other end of the telescopic rod, the clamp holds a sample dish with a hollow in the middle, the sample dish holds the diamond at the hollow position in the middle through a plurality of support rods, and an electric system for driving the telescopic rod to move and the disc to rotate.

[0020] To achieve the above-mentioned invention purpose, a diamond slicing method for dual-laser rotary machining provided by an embodiment of the present invention applies the above-mentioned diamond slicing system, and includes the following steps:

[0021] Step 1, respectively set the first optical parameter and the second optical parameter of the first laser and the second laser;

[0022] Step 2, the sample stage rotates to drive the diamond thereon to perform a spiral motion, and the first laser and the second laser emitted by the first laser and the second laser irradiate the diamond to achieve dual-laser rotary machining;

[0023] Step 3, after the laser machining is completed, perform slicing and peeling on the diamond.

[0024] Preferably, the tip of a metal probe is inserted into the edge of the diamond modification layer, and prying is completed through the metal probe to achieve slicing and peeling of the diamond.

[0025] Compared with the prior art, the beneficial effects of the present invention at least include:

[0026] The present invention uses two lasers to simultaneously irradiate a sample for processing, effectively controlling the amplitude of crack propagation in diamond materials. By adopting a processing method that combines modified particles and crack propagation, the probability of diamond material fragmentation is reduced.

[0027] The present invention halves the processing time and doubles the processing efficiency. Since the first laser and the second laser are incident on the diamond from opposite directions and act on the diamond simultaneously, the processing time is reduced. In addition, the corresponding loading and unloading time for multiple diamond processing is also eliminated.

[0028] The present invention can avoid the intersection of traces of multiple processing. By using two lasers for simultaneous processing, the processing traces of the two lasers are kept completely coincident.

[0029] The present invention can improve the processing path planning. For the same diamond, a rotary processing path is adopted, which can achieve the most uniform coverage of the large surface of the diamond during processing. Compared with a linear processing path, the rotary processing path has advantages. During linear processing, the laser will intermittently pass through the inside and the boundary of the diamond, easily generating a stress difference between the inside and the boundary, increasing the probability of diamond fragmentation. During rotary processing, the diamond inside is first uniformly processed, gradually moving outward, and finally reaching the diamond boundary, minimizing the stress difference to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 is a schematic diagram of a diamond crystal plane provided by an embodiment;

[0032] Figure 2 is a schematic structural diagram of a diamond slicing system provided by an embodiment;

[0033] Figure 3 is a specific structural diagram of a diamond slicing system provided by an embodiment;

[0034] Figure 4 is a schematic diagram of two lasers incident on a diamond provided by an embodiment;

[0035] Figure 5 is a schematic structural diagram of a sample stage provided by an embodiment;

[0036] Figure 6 is a schematic diagram of a rotary processing path provided by an embodiment;

[0037] Figure 7 It is a flowchart of diamond chip peeling passed by the embodiment. Specific Embodiments

[0038] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0039] In the prior art, laser is focused inside the diamond to directly generate processing marks, generate cracks inside the material and expand to form a crack surface. As Figure 1 shown, for the crystal structure of diamond material, when it is subjected to external energy, there is a chemical bond that is most easily broken, forming a crystal plane that is most easily cleaved, also called a cleavage plane, that is, the (111) crystal plane. When diamond is used as a semiconductor substrate, its large surface is usually the (100) crystal plane. There are differences between crystal planes. When laser acts on the interior of the material, due to fluctuations in the performance of the laser itself and inevitable random defects and dislocations during the growth of diamond, it is easy to cause uncontrollable crack formation, the material to break, and the crack direction to easily follow the (111) plane, with an angular difference from the (100) plane, and finally an irregular shape appears.

[0040] In the prior art, laser directly acts on diamond to generate processing marks. When the crack surface generated by processing is not complete, laser needs to be used again for multiple processing. And every time processing starts again, it is impossible to ensure that the sample placement is exactly the same as the previous time. Then, during the processing, the trend of the processing marks will inevitably change. The multiple processing marks cannot completely overlap, and there is an angular deviation between them.

[0041] To solve the above problems, the embodiment provides a diamond chip splitting system with dual-laser rotation processing, as Figure 2 shown, including a first laser 1, a second laser 2, a first optical path 3 and a second optical path 4, and a sample stage 5. Among them, the first laser 1 emits a first laser according to a first optical parameter, and the first laser irradiates diamond 6 on the sample stage 5 through the first optical path 3 in a first incident direction to generate modified particles inside the diamond 6; the second laser 2 emits a second laser according to a second optical parameter, and the second laser irradiates diamond 6 on the sample stage 5 through the second optical path 4 in a second incident direction to act on the modified particles inside the diamond 6, generate cracks based on the modified particles and expand; among them, the first optical parameter is different from the second optical parameter, and the first incident direction and the second incident direction are parallel and opposite. Particularly, the first incident direction and the second incident direction can be collinear, as Figure 3 shown. The sample stage 5 has a rotation function, driving the diamond on the sample stage to rotate to achieve dual-laser rotation processing.

[0042] In a diamond slicing system, there are differences between the first optical parameter and the second optical parameter. Using the first laser as the preliminary excitation light source, it induces material modification inside the diamond to form modified particles. The second laser is used for subsequent excitation to achieve the effect of expanding cracks. When the first laser acts on the diamond material, it does not generate cracks but generates modified particles, laying the foundation for the action of the second laser. The second laser does not directly act on the diamond material but acts on the aforementioned modified particles, generating and expanding cracks based on the modified particles. Compared with the prior art that directly uses a laser to generate cracks, the advantage of the dual-laser processing of the present invention is that through the step-by-step processing effect of the two lasers, the degree of crack generation in the diamond material is effectively controlled. The second laser generates cracks based on the modified particles, and the degree of cracking is controlled and will not be significantly superimposed along the (111) plane, thus avoiding the irregular shape caused by material fragmentation that may occur in the prior art.

[0043] In the embodiment, the first optical parameter includes the first pulse width, the first wavelength, the first repetition frequency, and the first power density, and the second optical parameter includes the second pulse width, the second wavelength, the second repetition frequency, and the second power density. Among them, the first pulse width and the second pulse width play a major role in the dual-laser rotary processing. The value range of the first pulse width is 10 fs - 1 ns, and the value range of the second pulse width is 0.1 ns - 100 ns, and the first pulse width is less than the second pulse width. Other wavelengths, repetition frequencies, and power densities play an auxiliary role in the dual-laser rotary processing. The value ranges of the first wavelength and the second wavelength are 0.35 μm - 3 μm, the value ranges of the first repetition frequency and the second repetition frequency are 1 Hz - 1 MHz, and the value ranges of the first power density and the second power density are 0.1 W / cm 2 - 10 W / cm 2 , and the magnitudes of the same type of optical parameters in the two sets of optical parameters are not limited. For example, for the optical parameter of wavelength, the first wavelength can be greater than, less than, or equal to the second wavelength.

[0044] Such as Figure 4As described above, both the first optical path 3 and the second optical path 4 include optical path components and focusing objectives along the laser transmission direction. Among them, the optical components of the first optical path 3 include a reflecting mirror 31, a half-wave plate 32, a beam expander group 33, a lens group 34, and another reflecting mirror 35 along the laser transmission direction. The size of the first laser focusing spot is changed by adjusting the distance between the focusing objective 36 and the diamond. The optical components of the second optical path 4 are the same as those of the first optical path, and also include a reflecting mirror 41, a half-wave plate 42, a beam expander group 43, a lens group 44, and another reflecting mirror 45 along the laser transmission direction. The size of the second laser focusing spot is changed by adjusting the distance between the focusing objective 46 and the diamond. Preferably, the size of the second laser focusing spot formed by the second laser should not be less than the size of the first laser focusing spot formed by the first laser, and should cover the first laser focusing spot, so that the second laser can act more comprehensively with the modified particle to generate cracks and expand, improving the processing effect.

[0045] In order to improve the processing effect, the power density of the laser can also be adjusted. Specifically, when the size of the laser focusing spot formed by the second laser on the diamond is larger than the size of the laser focusing spot formed by the first laser on the diamond, the second power density included in the second optical parameter is less than the first power density included in the first optical parameter.

[0046] Through the simultaneous processing of dual lasers, the present invention can ensure that the processing traces are completely on the same path, and there will be no angular deviation between the paths. The first laser and the second laser have different incident directions, and are respectively focused inside the diamond material from the upper and lower directions, and their optical paths do not affect each other. By adjusting optical parameters such as the focusing spot size and power density of the first laser and the second laser, the following processing effects can be achieved: the first laser first generates modified particles, and then the spot of the second laser acts on the modified particles.

[0047] As Figure 5 shown, the sample stage 5 includes a base 51, a bracket 52, a telescopic rod 53, a fixture 54, a sample tray 55, and a rod clamp 56. Among them, the base 51 and the bracket 52 can be assembled or disassembled. When assembled, they can be fixed on a flat tabletop, and when disassembled, the bracket 52 can be fixed on a marble rack; the telescopic rod 53 is connected to the bracket 52 and realizes telescoping through electric control of the mechanical thread; the fixture 54 and the sample tray 55 are combined. The fixture 54 clamps both ends of the sample tray 55 with balls embedded in the threads on the upper and lower surfaces of the sample tray 55, and the sample tray 55 is rotated by electric control; there are four support rods 56 inside the sample tray 55, which are fixed by the screws at the ends of the support rods 56 to clamp the diamond 6. Through the sample stage as Figure 5 shown, the diamond is clamped on the side by the fixture 54, so that the diamond can be stably suspended, and there is no obstruction on its upper and lower surfaces. Thus, the dual lasers can be incident from the upper and lower directions, as Figure 3The telescopic rod 53, the clamp 54 and the sample plate 55 are uniformly controlled by an electric system, and the telescopic speed of the telescopic rod and the rotation speed of the sample plate can be adjusted respectively, thereby adjusting the corresponding parameters during the processing.

[0048] The steps of diamond slicing based on the above dual laser rotary processing diamond slicing system include:

[0049] Step 1: respectively set the first optical parameter and the second optical parameter of the first laser and the second laser.

[0050] Step 2: The rotation of the sample stage drives the diamond thereon to make a spiral motion, and the first laser and the second laser emitted by the first laser and the second laser are irradiated onto the diamond to realize dual laser rotation processing.

[0051] Through the clamp 54, the telescopic rod 53 and the sample plate 55 can be adjusted in linkage to realize a rotary processing path on the diamond 6, such as Figure 6 shown. Figure 6 The medium and thin spiral line represents the processing path of the first laser, and the thick spiral line represents the processing path of the second laser. Since the first laser and the second laser are incident on the diamond 6 from the upper and lower directions respectively, and the incident positions on the upper and lower planes of the diamond 6 are the same, the processing paths of the first laser and the second laser completely overlap. During the processing, the telescopic rod 53 is extended and retracted, and the sample plate 54 rotates, driving the diamond 6 clamped in the middle of the sample plate 54 to move and rotate, while the positions of the first laser and the second laser are determined by the optical path and do not change. Since the optical parameters of the first laser and the second laser are different, by adjusting the focusing depth of the two lasers in the sample, the difference in the effect of the two lasers on the diamond can be effectively controlled. The first laser modifies the diamond 6 and realizes the modified point inside the diamond 6. The second laser deepens the light absorption and realizes the effect of expanding the crack on the modified point, so that the independent modified points can be connected through the crack to form a modified layer.

[0052] Step 3: After laser processing, the diamond is sliced ​​and peeled.

[0053] like Figure 7 As shown, use the tip of the metal probe to reach into the edge of the diamond modified layer. Because the modified layer is made of carbon and the material is loose, the metal probe can be used to pry it. Then stick double-sided tape on the upper and lower surfaces of the diamond, fit the handles respectively, and apply external force through the handles to complete the slicing operation.

[0054] The present invention uses rotary processing to process samples of the same area. The total path of rotary processing is shorter than that of linear processing. Accordingly, for a sample of the same size, the time consumed by rotary processing is less than that consumed by linear processing, and the processing efficiency is higher.

[0055] The specific embodiments described above have elaborated in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only the most preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, supplements, equivalent replacements, etc. made within the principle scope of the present invention shall be included within the protection scope of the present invention.

Claims

1. A diamond slicing system for dual-laser rotary processing, characterized in that, it includes a first laser, a second laser, a first optical path, a second optical path, and a sample stage; The first laser emits first laser according to first optical parameters, and the first laser irradiates the diamond on the sample stage through the first optical path in a first incident direction to generate modified points inside the diamond; The second laser emits second laser according to second optical parameters, and the second laser irradiates the diamond on the sample stage through the second optical path in a second incident direction to interact with the modified points inside the diamond, generating and expanding cracks based on the modified points; wherein, the first optical parameters are different from the second optical parameters, and the first incident direction and the second incident direction are parallel and opposite; The sample stage has a rotating function, driving the diamond on the sample stage to rotate to achieve dual-laser rotary processing.

2. The diamond slicing system for dual-laser rotary processing according to claim 1, characterized in that, The first optical parameters include a first pulse width, with a value range of 10 fs - 1 ns; the second optical parameters include a second pulse width, with a value range of 0.1 ns - 100 ns, and the first pulse width is less than the second pulse width.

3. The diamond slicing system for dual-laser rotary processing according to claim 2, characterized in that, The first optical parameters further include a first wavelength, a first repetition frequency, and a first power density, and the second optical parameters further include a second wavelength, a second repetition frequency, and a second power density; Among them, the value ranges of the first wavelength and the second wavelength are 0.35um - 3um, the value ranges of the first repetition frequency and the second repetition frequency are 1Hz - 1MHz, and the value ranges of the first power density and the second power density are 0.1W / cm 2 - 10W / cm 2 .

4. The diamond slicing system for dual-laser rotary processing according to claim 1, characterized in that, Both the first optical path and the second optical path include an optical path component and a focusing objective along the laser transmission direction, and the laser focusing spot size is changed by adjusting the distance from the focusing objective to the diamond.

5. The diamond slicing system for dual-laser rotary processing according to claim 4, characterized in that, The optical path component includes a reflecting mirror, a half-wave plate, a beam expander group, a lens group, and another reflecting mirror along the laser transmission direction.

6. The diamond slicing system for dual-laser rotary processing according to claim 4, characterized in that, When the laser focusing spot size formed by the second laser on the diamond is larger than the laser focusing spot size formed by the first laser on the diamond, the second power density included in the second optical parameters is less than the first power density included in the first optical parameters.

7. The diamond slicing system for dual-laser rotary processing according to claim 1, characterized in that, The sample stage includes a base, a bracket arranged on the base, a telescopic rod arranged on the bracket, a clamp connected to the other end of the telescopic rod, the clamp holds a sample disk with a hollow middle, the sample disk holds the diamond at the hollow middle position through multiple support rods, and an electric system for driving the telescopic rod to move and the disk to rotate.

8. A diamond slicing method for dual-laser rotary processing, characterized in that, The method applies the diamond slicing system according to any one of claims 1 - 7, and includes the following steps: Step 1, respectively set the first optical parameters and the second optical parameters of the first laser and the second laser; Step 2: The sample stage rotates to drive the diamond thereon to perform a spiral motion. The first laser and the second laser emitted by the first laser and the second laser irradiate the diamond, realizing dual-laser rotary machining; Step 3: After the laser machining is completed, the diamond is sliced and peeled off.

9. The diamond slicing method by dual-laser rotary machining according to claim 8, characterized in that, the tip of a metal probe is inserted into the edge of the diamond modification layer, and prying is completed through the metal probe to realize the slicing and peeling of the diamond.

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