Cutting method and cutting device for CVD diamond wafer

Abstract

The present invention relates to the technical field of cutting CVD diamond wafers, and discloses a cutting method and a cutting device for CVD diamond wafers. The cutting method includes introducing a reaction gas into the diamond to be cut. The reaction gas is an oxygen-containing gas, which increases the oxygen concentration around the diamond to be cut. The reaction gas is used as a carrier for carbon black powder, and the carbon black powder is used to absorb the laser to prevent the laser from diverging, reflecting or refracting into the non-cutting area of the diamond to be cut. Then, laser cutting is performed on the diamond to be cut. A gas flow channel is formed on the cutting device for the reaction gas to flow through, or one or more nozzles are provided on the cutting device, and the reaction gas is introduced through the nozzles. By using the oxygen-containing reaction gas externally added by the cutting device and using the reaction gas to carry the carbon black powder, the cutting efficiency is improved, the refraction and divergence of the laser are reduced, the influence of the laser heat on the non-diamond area is reduced, the CVD diamond wafer is protected, and the diamond wafer is prevented from cracking.

Description

Technical Field

[0001] The present invention relates to the technical field of CVD diamond wafer cutting, and particularly relates to a cutting method and a cutting device for CVD diamond wafers. Background Art

[0002] Diamond is the hardest substance known in nature, and cutting and polishing diamond are relatively difficult. Currently, laser cutting of diamond is the main method. The principle of laser cutting diamond is to focus the energy of the laser to convert the sp3-hybridized diamond phase into the sp2-hybridized graphite phase, thereby completing the cutting of the diamond. Due to the good thermal conductivity of diamond, the heat generated by the laser during the cutting process will be conducted to the non-cutting area; and due to the good transparency of diamond, the laser is also prone to refraction and divergence, thus entering the non-cutting area of the diamond. In summary, the non-cutting area of the diamond is prone to thermal damage and cracking during the cutting process.

[0003] Patent CN 114232090 B proposes that before cutting CVD diamond, an optically modified coating is applied on the surface of the CVD diamond. The optically modified coating can prevent the divergence of the laser caused by the uneven refractive index of the diamond, and the toughening effect of the optically modified film can also reduce the cracking phenomenon of the diamond. Patent CN 115846899 B also proposes that before laser cutting CVD diamond, an optical antireflection film and a carbon black colloidal film are deposited on the lower surface of the CVD diamond. The main function is still to protect the diamond wafer from laser damage and reduce the cracking of CVD diamond when laser cutting the CVD diamond wafer. It can be seen that the problem of diamond cracking caused by laser cutting CVD diamond wafers is relatively serious. Although the method of coating before cutting CVD diamond wafers can reduce the divergence of the laser caused by the uneven refractive index of the diamond, the cost is relatively high and the process is relatively complex, and it cannot cut CVD diamond simply and efficiently. Summary of the Invention

[0004] In order to reduce the damage of laser cutting diamond, the present invention patent proposes a cutting method and a cutting device for CVD diamond wafers, which use the cutting device to add an oxygen-containing reaction gas and carry carbon black powder with the reaction gas to improve the cutting efficiency, reduce the refraction and divergence of the laser, reduce the influence of laser heat on the non-diamond area, protect the CVD diamond wafer, and avoid the cracking of the diamond wafer.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A cutting method for CVD diamond wafers, comprising

[0007] Introducing a reaction gas into the diamond to be cut, the reaction gas being an oxygen-containing gas to increase the oxygen concentration around the diamond to be cut;

[0008] Using the reaction gas as a carrier for carbon black powder, the carbon black powder is used to absorb the laser to prevent the laser from diverging, reflecting or refracting into the non-cutting area of the diamond to be cut, and the oxygen content ratio after mixing the reaction gas and the carbon black powder is greater than 21%;

[0009] Laser cut the diamond to be cut.

[0010] Furthermore, after mixing the reaction gas and the carbon black powder, an air column is formed, and the position of the air column coincides with the laser cutting area.

[0011] Furthermore, the reaction gas continuously flows during the laser cutting process and the flow rate is adjustable.

[0012] Furthermore, the reaction gas includes single gases such as oxygen and carbon dioxide, or a mixed gas, or a mixed gas with argon.

[0013] Furthermore, the particle size of the carbon black powder is set to 2 to 10 microns.

[0014] A cutting device for a CVD diamond wafer, applying a cutting method for a CVD diamond wafer as described above. An air inlet, a feed inlet and a material mixing chamber communicating with the feed inlet are provided on the cutting device. The air inlet is for introducing the reaction gas, the feed inlet is for introducing the carbon black powder, the material mixing chamber is for mixing the carbon black powder and the reaction gas, and one or more nozzles are provided on the cutting device. The nozzles are used to eject the mixture of the reaction gas and the carbon black powder and form an air column.

[0015] Furthermore, the cutting device includes a laser generator. The nozzle moves synchronously with the laser generator, and the nozzle is arranged towards the cutting area. The cutting area is specifically the area where the laser generated by the laser generator coincides with the diamond wafer at the same moment.

[0016] Furthermore, the ejection pressure of the nozzle is set between 0.4 Mpa and 0.7 Mpa.

[0017] Advantages of the present invention:

[0018] 1. The principle of laser cutting diamond is to use the energy of the focused laser to convert the sp3 hybridized diamond phase into the sp2 hybridized graphite phase, thereby completing the cutting of the diamond. The strong oxidation of the oxygen-containing reaction gas on the diamond at high temperature makes the CVD diamond easier to carbonize, which can promote the graphitization of the diamond in the cutting area, reduce the cutting time and heat transfer, and thus improve the cutting efficiency of the laser;

[0019] 2. In the present invention, the reaction gas can serve as a carrier for carrying carbon black powder, enabling the carbon black powder to smoothly enter the area of laser cutting diamond. The main function of the carbon black powder is to absorb the laser scattered beam and block the laser from refracting into the non-cutting area of the diamond, thereby reducing the influence of the laser on the non-cutting area of the diamond, protecting the CVD diamond wafer, and avoiding cracking of the diamond wafer.

[0020] 3. Compared with the method of coating a carbon black glue layer on the diamond wafer in the prior art, the present invention uses carbon black powder to absorb the laser to avoid the laser from diverging, reflecting, or refracting into the non-cutting area of the diamond to be cut. There is no need to process the diamond wafer before and after cutting the diamond wafer, which simplifies the process flow, makes the process simple, and has high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the overall structure of the cutting device in Embodiment 2 of the present invention;

[0022] REFERENCE SIGNS:

[0023] 1. Convex lens; 2. Laser beam; 301. Feed inlet; 3. Material mixing chamber; 4. Nozzle; 5. Diamond wafer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component at the same time. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0027] Example 1:

[0028] A cutting method for a CVD diamond wafer, comprising:

[0029] Step 1: Install a jet device on the cutting and mounting device, which can transport gas and adjust the gas flow rate; in this step, the jet device is specifically set as a nozzle, and the ejection pressure of the nozzle is set between 0.4 Mpa and 0.7 Mpa.

[0030] Step 2: Before cutting, introduce a reaction gas into the diamond to be cut. The reaction gas is an oxygen-containing gas, which increases the oxygen concentration around the diamond to be cut; at high temperatures, the strong oxidation of the oxygen-containing reaction gas on the diamond makes the CVD diamond more prone to carbonization, which can promote the graphitization of the diamond in the cutting area, reduce the cutting time and heat transfer, thereby improving the cutting efficiency of the laser.

[0031] Step 3: Use the reaction gas as a carrier for carbon black powder. The carbon black powder is used to absorb the laser to prevent the laser from diverging, reflecting or refracting into the non-cutting area of the diamond to be cut. The oxygen content ratio of the reaction gas mixed with the carbon black powder is greater than 21%. The reaction gas and the carbon black powder are mixed to form an air column, and the position of the air column coincides with the laser cutting area; in the present invention, the reaction gas can be used as a carrier for carrying the carbon black powder, so that the carbon black powder can smoothly enter the area where the diamond is cut by the laser. The main function of the carbon black powder is to absorb the laser scattering beam and block the laser from refracting into the non-cutting area of the diamond, thereby reducing the influence of the laser on the non-cutting area of the diamond, protecting the CVD diamond wafer and avoiding cracking of the diamond wafer; the present invention uses carbon black powder to absorb the laser to prevent the laser from diverging, reflecting or refracting into the non-cutting area of the diamond to be cut, without the need to process the diamond wafer before and after cutting the diamond wafer, reducing the process flow, making the process simple and having high production efficiency. Step 4: Turn on the cutting equipment and perform laser cutting on the diamond to be cut. The laser power is set to 65W - 80W, the cutting speed is set to 60mm / min - 90mm / min, and the pulse frequency is set to 30Hz - 60Hz.

[0032] The reaction gas includes single gases such as oxygen and carbon dioxide, or a mixed gas, or a mixed gas with argon. The particle size of the carbon black powder is set to 2 to 10 microns. The reaction gas continuously flows during the laser cutting process and the flow rate can be adjusted.

[0033] Here, the carbon black powder has multiple functions: 1) The carbon black powder can better absorb the laser, convert the light energy of the laser into heat energy, thereby increasing the rate of the oxidation reaction; 2) The carbon black powder is sprayed around the cutting point. While absorbing the laser, it can prevent the laser from penetrating into the interior of the diamond and damaging the diamond components inside the dividing surface; 3) If the spraying amount of the carbon black powder is increased (resulting in the incomplete combustion of the carbon black powder, which will impact the diamond structure of the cutting surface in a solid state), or some non-oxidizable fine powders such as silicon dioxide particles are added to the carbon black powder, it can play a mechanical role in solid erosion of the diamond cutting surface while the diamond undergoes a chemical reaction under high-temperature ablation, reducing the ablation residue and improving the cutting efficiency.

[0034] Example 2:

[0035] A cutting device for a CVD diamond wafer, applying a cutting method for a CVD diamond wafer as described above, as Figure 1 shown, an air inlet, a feed port 301, and a material mixing chamber 3 communicating with the feed port 301 are provided on the cutting device. The air inlet (not shown in the figure) is for introducing the reaction gas. The air inlet is the same as that of a conventional laser cutting device, so it is not shown in the drawings of this application. The feed port 301 is for introducing the carbon black powder, and the material mixing chamber 3 is for mixing the carbon black powder and the reaction gas. The reaction gas can be pre-mixed outside the cutting device and then introduced into the material mixing chamber 3, or the reaction gas can be introduced into the material mixing chamber 3 and then mixed with the carbon black powder. One or more nozzles 4 are provided on the cutting device, and the nozzles 4 are used to eject the mixture of the reaction gas and the carbon black powder and form an air column.

[0036] The cutting device includes a laser generator. The laser generator includes a convex lens 1. The laser generator emits a laser beam 2, and the laser beam 2 is focused on the diamond wafer 5 through the convex lens 1. The nozzle 4 moves synchronously with the laser generator. The nozzle 4 is arranged towards the cutting area, and the cutting area is specifically the area where the laser beam 2 generated by the laser generator coincides with the diamond wafer 5 at the same moment. The ejection pressure of the nozzle is set between 0.4 Mpa and 0.7 Mpa.

[0037] In this embodiment, the cutting device is improved. In the prior art, pure gas is added in laser cutting, and the function is single. In the design of this patent, the gas is used as a carrier gas, mainly playing the role of transporting materials (black substances), and at the same time taking into account the activation effect.

[0038] The particle size of the carbon black powder is set to 2 to 10 microns, and the reaction gas continuously flows during the laser cutting process with an adjustable flow rate. The experimental equipment uses an NSC-LC-100 type Nd:YAG pulsed laser cutter, with a pulse width τ = 100 μs, a maximum laser output power of 100 W, and the gas is compressed O2. The cutting material is PCD, with a specification of φ42×1.6 mm. When conducting the cutting experiment, two groups of four-factor and four-level orthogonal experiments are carried out. The first group is the control group, using the conventional laser cutting method without adding carbon black powder. The second group adds carbon black powder, and the particle size of the carbon black powder is set to 2 to 10 microns. The process parameters are shown in Table 1, and all the experiments are one-way straight cutting.

[0039] Table 1 Orthogonal experiment process parameters

[0040] Serial number Parameter Value A Laser power P: W 65，70，75，80 B Cutting rate v: mm / min 60，70，80，90 C Pulse frequency f: Hz 30，40，50，60 D Outlet pressure p: Mpa 0.4，0.5，0.6，0.7

[0041] According to the orthogonal table, 16 groups of experiments are carried out. The upper seam width, lower seam width, and surface are measured for different experimental schemes. The obtained experimental results are shown in Table 2.

[0042] Table 2 Orthogonal experiment results of the control group

[0043]

[0044]

[0045] It can be seen from the experimental results that the minimum upper seam width of the laser-cut PCD sheet is 175.61 μm, and the maximum difference is 88.58 μm; the minimum surface roughness Ra is 0.50 μm, and the maximum difference is 0.91 μm. It can be seen that the laser cutting seam width and surface roughness vary greatly under different parameters, which has an important impact on the control of the surface quality and dimensional accuracy of the cutting material. Therefore, it is necessary to analyze the influence of parameters on the cutting quality from different angles to optimize the cutting process.

[0046] The experiment is verified according to the optimal scheme. The process parameters are a laser power of 80 W, a cutting speed of 70 mm / min, a pulse frequency of 50 Hz, and an outlet pressure of 0.6 MPa. The measured upper seam width is 177.42 μm, and the surface roughness Ra = 0.88 μm. The experimental results are close to those measured in the 5th group.

[0047] The experimental group carried out 16 groups of experiments according to the orthogonal table, and the experimental results are shown in Table 3.

[0048] Table 3 Orthogonal experiment results of the experimental group

[0049]

[0050]

[0051] It can be seen from the test results that the minimum width of the laser-cut slit on the PCD sheet is 141.41 μm, and the maximum difference is 71.26 μm; the minimum surface roughness Ra is 0.55 μm, and the maximum difference is 0.75 μm. It can be seen that after adding carbon black powder under different parameters, the distribution of the laser-cut slit width and surface roughness is more concentrated, and the slit width is significantly reduced, which has an improvement effect on the control of the surface quality and dimensional accuracy of the cutting material.

[0052] The test was verified according to the optimal plan. The process parameters were laser power 65 W, cutting speed 90 mm / min, pulse frequency 60 Hz, and outlet pressure 0.6 MPa. The measured upper slit width was 143.17 μm, and the surface roughness Ra = 0.78 μm. The test results were close to those measured in the 5th group.

[0053] The above is only the preferred implementation mode of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for cutting a CVD diamond sheet, characterized in that: include Passing a reaction gas into the diamond to be cut, wherein the reaction gas is an oxygen-containing gas so that the oxygen concentration around the diamond to be cut increases; The reaction gas is used as a carrier of carbon black powder, the carbon black powder is used to absorb laser light to prevent the laser light from diverging, reflecting or refracting into the non-cutting area of ​​the diamond to be cut, and the oxygen content of the reaction gas after mixing with the carbon black powder is greater than 21%; Laser cutting of diamond to be cut.

2. The method for cutting a CVD diamond sheet according to claim 1, characterized in that: The reaction gas is mixed with the carbon black powder to form a gas column, and the position of the gas column coincides with the laser cutting area.

3. The method for cutting a CVD diamond sheet according to claim 1, characterized in that: The reaction gas flows continuously during the laser cutting process and the flow rate is adjustable.

4. The method for cutting a CVD diamond sheet according to claim 1, characterized in that: The reaction gas includes oxygen, carbon dioxide, single gas or mixed gas or mixed gas with argon.

5. The method for cutting a CVD diamond sheet according to claim 1, characterized in that: The particle size of the carbon black powder is set to be 2 to 10 microns.

6. A CVD diamond sheet cutting device, using a CVD diamond sheet cutting method according to any one of claims 1 to 5, characterized in that: The cutting device is provided with an air inlet, a feed port and a material mixing chamber connected to the feed port, the air inlet is for the reaction gas to pass through, the feed port is for the carbon black powder to pass through, the material mixing chamber is for mixing the carbon black powder and the reaction gas, and the cutting device is provided with one or more nozzles, and the nozzles are used to spray out the mixture of the reaction gas and the carbon black powder to form an air column.

7. A CVD diamond sheet cutting device according to claim 6, characterized in that: The cutting device comprises a laser generator, the nozzle moves synchronously with the laser generator, and the nozzle is arranged toward a cutting area, and the cutting area is specifically an area where the laser generated by the laser generator overlaps with the diamond sheet at the same time.

8. The CVD diamond sheet cutting device according to claim 6, characterized in that: The ejection pressure of the nozzle is set between 0.4Mpa and 0.7Mpa, the laser cutting rate is set between 60mm / min-90mm / min, the pulse frequency is set between 30Hz-60Hz, and the laser power is set between 65W-80W.

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