Polycrystalline diamond surface machining method

Abstract

The invention discloses a polycrystalline diamond surface machining method, and belongs to the technical field of polycrystalline diamond surface machining. The processing method comprises the following steps: (1) carrying out laser thinning on the surface of the polycrystalline diamond by adopting laser; (2) the surface of the polycrystalline diamond subjected to laser thinning is polished, a polishing solution adopted for polishing comprises 0.02-0.1 part of a polishing abrasive, 0.02-0.1 part of transition metal micro powder and 1 part of water, the pH of the polishing solution is adjusted to be 10-11 through an alkaline substance, the alkaline substance is selected from at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide, and the pH of the polishing solution is adjusted to be 10-11 through an alkaline agent; the polishing abrasive is selected from at least one of diamond, silicon carbide and boron carbide. According to the method, the surface of the polycrystalline diamond is subjected to laser thinning and polishing treatment, so that the high flatness of the surface of the polycrystalline diamond can be improved, the roughness is reduced, and the uniformity of the surface type quality is improved.

Description

Technical Field

[0001] The present application relates to a method for processing a polycrystalline diamond surface, and belongs to the technical field of polycrystalline diamond surface processing. Background Art

[0002] Diamond has the highest thermal conductivity in nature, which can effectively dissipate heat and significantly improve the reliability and performance of high-power electronic devices. In addition, diamond also shows excellent stability in extreme environments such as high temperature, radiation resistance and corrosion resistance, and is suitable for aerospace, national defense and deep-sea exploration.

[0003] However, compared with other semiconductor materials, diamond has the characteristics of high hardness, high wear resistance and strong rigidity, so the surface quality of diamond crystal materials is often very low. For single-crystal diamond, its grain arrangement is generally more uniform, and a higher quality surface can be obtained through processing conditions. However, for polycrystalline diamond, it is composed of grains of different crystal forms, so the grain arrangement of polycrystalline diamond is more likely to be disordered, and the surface roughness of the obtained polycrystalline diamond will be very high, making it difficult to obtain a surface with high flatness, low roughness and uniform surface quality through subsequent processing methods. Summary of the invention

[0004] In order to solve the above problems, a method for processing a polycrystalline diamond surface is provided. The method can improve the flatness of the polycrystalline diamond surface, reduce the roughness, and improve the uniformity of the surface quality by performing laser thinning and polishing on the surface of the polycrystalline diamond.

[0005] The present application provides a method for processing a polycrystalline diamond surface, comprising the steps of:

[0006] (1) Using laser to thin the surface of polycrystalline diamond;

[0007] (2) polishing the surface of the laser-thinned polycrystalline diamond, wherein the polishing liquid comprises, by weight, 0.02 to 0.1 parts of polishing abrasive, 0.02 to 0.1 parts of transition metal powder and 1 part of water, the pH of the polishing liquid is adjusted to 10 to 11 by an alkaline substance, the alkaline substance is selected from at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide, and the polishing abrasive is selected from at least one of diamond, silicon carbide and boron carbide.

[0008] In the above processing method, laser thinning is performed on the surface of polycrystalline diamond by laser, which can reduce the surface TTV of polycrystalline diamond to 10μm, Warp to 20μm, BOW to 10μm, and roughness to 0.5μm; therefore, the above laser thinning treatment of the surface of polycrystalline diamond can achieve flattening of the surface of polycrystalline diamond to overcome the problem of high surface roughness caused by stacking of polycrystalline grains and difficulty in obtaining a high-quality surface through polishing.

[0009] After laser thinning, polishing is performed. Under alkaline conditions, the transition metal powder of the present application catalyzes the amorphization of polycrystalline diamond during the movement and friction with the surface of polycrystalline diamond. It can soften the surface layer of polycrystalline diamond, thereby cooperating with polishing abrasive to remove the softened amorphous layer. The polishing liquid can improve the polishing efficiency of the polycrystalline diamond surface and improve the surface quality after polishing.

[0010] Since polycrystalline diamond is a product composed of diamond grains with different orientations, the different grain orientations lead to different properties, so the trend, rate and degree of transformation to amorphous are also different. If the rate difference of grains with different orientations to amorphous is too large, there will be softened areas and non-softened areas on the surface of the polycrystalline diamond during the polishing process, which will not only reduce the polishing efficiency, but also significantly increase the surface roughness of the polycrystalline diamond after polishing, and significantly reduce the surface flatness. In the polishing process of this application, when the transition metal powder plays a role in catalyzing the transformation of polycrystalline diamond to amorphous, it can coordinately adjust the rate of transformation of diamond grains with different crystal orientations to amorphous, so that the softening consistency of the polycrystalline diamond surface is increased, thereby significantly reducing the surface roughness and surface flatness of the polycrystalline diamond.

[0011] Optionally, in step (1), the wavelength of the laser is 325-532 nm.

[0012] If the laser wavelength is too low, the processing efficiency will be too low due to the low penetration depth of the laser on the diamond surface. If the laser wavelength is too high, the energy distribution will be difficult to control due to the high penetration depth of the laser on the diamond surface and the processing quality will deteriorate due to the wide longitudinal distribution.

[0013] Optionally, in step (1), the power of the laser is 10 to 50 W, the frequency is 6 to 10 kHz, and the moving speed is 200 to 600 mm / min.

[0014] If the laser power is too high, the heat affected zone will be too large, resulting in excessive laser processing damage and affecting subsequent processing. If the power is too low, the processing efficiency will be too slow. If the frequency is too high, the energy of the laser single pulse will be too low to effectively process diamonds. If the frequency is too low, the uniformity between pulses will deteriorate. If the moving speed is too fast, the processing efficiency will be too poor. If the moving speed is too slow, the processing surface quality will be poor.

[0015] Optionally, the laser thinning cutting lines are spaced 10 to 30 μm apart.

[0016] Cutting paths refer to the excessive ablation marks caused by uneven light intensity distribution during the moving cutting process of the laser. The above-mentioned cutting path interval can ensure uniform removal of the diamond surface. If the interval is too small, it will cause the cutting paths to stack and reduce processing efficiency and the quality of the stacking will be poor. If the interval is too large, the removal rate of the area between the cutting paths will be slow during the cutting process, resulting in poor processing surface shape.

[0017] Optionally, the polishing abrasive has a particle size of 0.2 to 1 μm.

[0018] Optionally, in step (2), the polishing abrasive is selected from diamond and silicon carbide in a weight ratio of 1:1.

[0019] Optionally, in step (2), the transition metal powder is selected from at least one of iron, cobalt, nickel, copper and manganese.

[0020] The pH of the polishing liquid matches the type of transition metal powder, which can improve the catalytic effect on the surface of polycrystalline diamond, thereby improving the polishing efficiency, and can also improve the consistency of catalysis on diamonds of different crystal forms, thereby improving the surface quality after polishing and reducing surface roughness.

[0021] Preferably, the particle size of the transition metal powder is 0.2 to 10 μm.

[0022] The particle size of the transition metal powder is larger than that of the polishing abrasive, which can not only catalyze the amorphization of polycrystalline diamond during the polishing process, but also achieve rough polishing of polycrystalline diamond, while the polishing abrasive achieves fine polishing. The particle size of the transition metal powder is compatible with the particle size of the polishing abrasive, and the polishing of polycrystalline diamond can be efficiently achieved. If the particle size of the transition metal powder is too small, it is easy to agglomerate and the catalytic uniformity becomes poor. If the particle size of the transition metal powder is too large, the specific surface area is low, resulting in reduced catalytic efficiency, which affects the processing efficiency and processing quality.

[0023] Optionally, in step (2), the flow rate of the polishing liquid during the polishing process is 0.1 to 1 L / min, and the pressure is 100 to 600 g / cm 2 .

[0024] Optionally, before the polishing in step (2), a pre-polishing step is also included, wherein the pre-polishing solution comprises diamond powder, hydrogen peroxide and water in a weight ratio of (0.05-0.1):(0.05-0.1):1.

[0025] The pre-polishing setting can achieve rapid removal of the surface damage layer before polishing, improve polishing efficiency, and remove impurities remaining after laser thinning, laying the foundation for the smooth progress of subsequent polishing. In addition, the polishing process can achieve pretreatment of various crystalline diamonds, thereby facilitating the catalytic amorphization of diamonds by transition metal micropowders in subsequent polishing, further improving the transformation consistency of the catalytic amorphization of various crystalline diamonds, and improving the surface quality of the final polycrystalline diamond and the surface consistency of mass-produced polycrystalline diamonds.

[0026] Optionally, the particle size of the diamond powder in the pre-polishing liquid is 0.5-2 μm.

[0027] Optionally, the pre-polishing removal thickness is 0.5-3 μm.

[0028] The beneficial effects of this application include but are not limited to:

[0029] 1. The polycrystalline diamond surface processing method of the present application adopts a laser thinning process to thin the polycrystalline diamond surface, which can flatten the rough surface caused by the disordered arrangement of grains, so that the TTV of the polycrystalline diamond surface is significantly reduced, providing favorable conditions for subsequent primary polishing and secondary polishing.

[0030] 2. The polycrystalline diamond surface processing method of the present application uses different polishing liquids and polishing processes to perform two-step polishing treatment on the polycrystalline diamond surface after the laser thinning process operation, which can greatly improve the surface quality of the polycrystalline diamond and improve the consistency of the surface quality of the polycrystalline diamond.

[0031] 3. The polycrystalline diamond surface processing method of the present application is easy to operate and the process parameters are easy to control. It can improve the processing efficiency of the polycrystalline diamond surface, reduce the probability of edge collapse, cracks, etc., and improve the product yield. The above-mentioned processing will not have an adverse effect on other properties of polycrystalline diamond (such as thermal conductivity, transmittance, thermal expansion coefficient), and is convenient for industrial promotion and use.

[0032] 4. The polycrystalline diamond surface processing method of the present application has high universality and can be used not only to process polycrystalline diamond substrates, but also to process composite substrates including polycrystalline diamond layers, so that the surface parameters such as TTV, Warp, BOW, and roughness of the processed polycrystalline diamond surface are significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0034] Figure 1 This is a schematic diagram of the structure of the laser thinning equipment involved in the laser thinning operation of this application.

[0035] Figure 2 This is a surface intuitive and microscopic observation view of the polycrystalline diamond surface at different stages involved in Example 1 of the present application.

[0036] List of parts and reference numerals:

[0037] 1. Operating table; 2. Y translation plate; 3. X translation plate; 4. Sample tray; 5. Sample; 6. Laser head; 7. Support frame. DETAILED DESCRIPTION

[0038] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0039] Unless otherwise specified, the raw materials in the examples and comparative examples of the present application were purchased through commercial channels.

[0040] Unless otherwise specified, the methods used in the examples and comparative examples of the present application are conventional methods in the prior art.

[0041] In the following embodiments and comparative examples, laser thinning of the polycrystalline diamond surface is performed by Figure 1 The laser thinning device shown in the figure is operated, and the laser thinning device includes a laser head and a sample tray, an X translation plate, a Y translation plate, and an operating table arranged from top to bottom; the sample tray is used to place the sample, and the laser head emits laser to perform laser thinning on the sample; the Y translation plate is arranged on the operating table, and can move relative to the operating table in the Y direction to drive the X translation plate, the sample tray and the sample to move in the Y direction; the X translation plate is arranged on the Y translation plate, and can move relative to the Y translation plate in the X direction to drive the sample tray and the sample to move in the X direction, and the X direction is perpendicular to the Y direction.

[0042] The above X direction and Y direction are only used to distinguish the sample plate in two different and perpendicular directions. Both directions drive the sample plate to move in the horizontal direction. From the front of the laser thinning device, when the X direction is the left-right movement, the Y direction is the front-back movement; when the X direction is the front-back movement, the Y direction is the left-right movement.

[0043] The above-mentioned way of moving the Y translation plate relative to the operating table along the Y direction and the way of moving the X translation plate relative to the Y translation plate along the X direction can both adopt the operation methods commonly used in the prior art, such as driving the gear along the rack by a rotating motor, or by electromagnetically driving the slide rail along the slot.

[0044] The laser head can emit laser to perform laser thinning on the sample. Since the X-translation plate and the Y-translation plate can drive the sample to move in the horizontal direction, the laser head can be set to a fixed form. The laser head can be fixed to one side of the sample stage through an additional fixing device. You can also refer to Figure 1 , the straight drop is fixed on the sample stage through a support frame, and the support frame only needs to not hinder the movement of the Y translation plate and the X translation plate.

[0045] Example 1

[0046] This embodiment relates to a method for processing a polycrystalline diamond surface, comprising the steps of:

[0047] (1) The surface of polycrystalline diamond is laser thinned by laser, the wavelength of the laser is 325 nm, the power is 50 W, the frequency is 6 kHz, the moving speed is 600 mm / min, and the cutting path interval of the laser thinning is 30 μm;

[0048] (2) polishing the surface of the laser-thinned polycrystalline diamond, wherein the polishing liquid used for the polishing comprises, by weight, 0.02 parts of silicon carbide, 0.02 parts of iron metal powder and 1 part of water, the pH of the polishing liquid is adjusted to 11 by lithium hydroxide, the particle size of the silicon carbide is 1 μm, and the particle size of the iron metal powder is 10 μm; the flow rate of the polishing liquid during the polishing process is 0.1 L / min, and the pressure is 100 g / cm 2 .

[0049] Example 2

[0050] This embodiment relates to a method for processing a polycrystalline diamond surface, comprising the steps of:

[0051] (1) The surface of polycrystalline diamond is laser thinned by laser, the wavelength of the laser is 532 nm, the power is 10 W, the frequency is 10 kHz, the moving speed is 200 mm / min, and the cutting path interval of the laser thinning is 10 μm;

[0052] (2) Polishing the surface of the laser-thinned polycrystalline diamond, wherein the polishing liquid used for polishing comprises, by weight, 0.1 part of boron carbide, 0.1 part of copper metal powder and 1 part of water, the pH of the polishing liquid is adjusted to 10 by potassium hydroxide, the particle size of the boron carbide is 0.2 μm, and the particle size of the copper metal powder is 0.2 μm; the flow rate of the polishing liquid during the polishing process is 1 L / min, and the pressure is 600 g / cm 2 .

[0053] Example 3

[0054] This embodiment relates to a method for processing a polycrystalline diamond surface, comprising the steps of:

[0055] (1) The surface of polycrystalline diamond is laser thinned by laser, the wavelength of the laser is 532nm, the power is 30W, the frequency is 10kHz, the moving speed is 400mm / min, and the cutting path interval of the laser thinning is 20μm;

[0056] (2) Polishing the surface of the laser-thinned polycrystalline diamond, wherein the polishing liquid used for polishing comprises, by weight, 0.05 parts of diamond, 0.05 parts of nickel metal powder and 1 part of water, the pH of the polishing liquid is adjusted to 10 by sodium hydroxide, the particle size of the diamond is 0.8 μm, and the particle size of the nickel metal powder is 5 μm; the flow rate of the polishing liquid during the polishing process is 0.6 L / min, and the pressure is 300 g / cm 2 .

[0057] Example 4

[0058] The difference between this embodiment and embodiment 3 is that cobalt metal powder is used to replace nickel metal powder, and the rest is the same as embodiment 3.

[0059] Example 5

[0060] The difference between this embodiment and embodiment 3 is that manganese metal powder is used to replace nickel metal powder, and the rest is the same as embodiment 3.

[0061] Example 6

[0062] The difference between this embodiment and embodiment 3 is that the particle size of diamond is 1.5 μm, and the rest is the same as embodiment 3.

[0063] Example 7

[0064] The difference between this embodiment and embodiment 3 is that the particle size of the nickel metal powder is 12 μm, and the rest is the same as embodiment 3.

[0065] Example 8

[0066] The difference between this embodiment and embodiment 3 is that the pressure during the polishing process is 700g / cm 2 , the rest is the same as Example 3.

[0067] Example 9

[0068] The difference between this embodiment and embodiment 3 is that the wavelength of the laser is 635 nm, and the rest is the same as embodiment 3.

[0069] Example 10

[0070] The difference between this embodiment and embodiment 3 is that the power of the laser is 55 W and the frequency is 12 kHz, and the rest is the same as embodiment 3.

[0071] Embodiment 11

[0072] The difference between this embodiment and embodiment 3 is that before the polishing in step (2), it also includes a step of pre-polishing with a pre-polishing liquid, the pre-polishing liquid includes diamond powder, hydrogen peroxide and water in a weight ratio of 0.1:0.05:1, the particle size of the diamond powder is 2 μm, the pre-polishing removal thickness is 2 μm, and the rest is the same as embodiment 3.

[0073] Example 12

[0074] The difference between this embodiment and embodiment 3 is that before the polishing in step (2), it also includes a step of pre-polishing with a pre-polishing liquid, the pre-polishing liquid includes diamond powder, hydrogen peroxide and water in a weight ratio of 0.2:0.1:1, the particle size of the diamond powder is 0.5 μm, the pre-polishing removal thickness is 5 μm, and the rest is the same as embodiment 3.

[0075] Embodiment 13

[0076] The difference between this embodiment and embodiment 12 is that the pre-polishing liquid includes diamond powder, hydrogen peroxide and water in a weight ratio of 0.2:0.15:1, and the rest is the same as embodiment 3.

[0077] Embodiment 14

[0078] The difference between this embodiment and embodiment 12 is that the particle size of the diamond powder in the pre-polishing liquid is 3 μm, and the rest is the same as embodiment 3.

[0079] Embodiment 15

[0080] The difference between this embodiment and embodiment 3 is that silicon carbide and diamond in a weight ratio of 1:1 are used to replace diamond, the particle size of silicon carbide is the same as that of diamond, and the rest is the same as embodiment 3.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 3 is that the pH value of the polishing liquid is adjusted to 9 by using sodium hydroxide, and the rest is the same as Example 3.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 3 is that the nickel metal powder in the polishing liquid is 0.2 parts, and the rest is the same as Example 3.

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 3 is that the diamond polishing abrasive in the polishing liquid is 0.2 parts, and the rest is the same as Example 3.

[0087] Experimental example

[0088] The surface roughness, TTV, BOW and Warp tests were performed on the polycrystalline diamonds prepared in the above embodiments and comparative examples. The test results are shown in Table 1 below.

[0089] Table 1

[0090]

[0091]

[0092] Figure 2 The surface visual images and microscopic observations of the polycrystalline diamond surface involved in Example 12 before laser thinning, after laser thinning, and after two-step polishing are shown, wherein Figure 2 (a) is a visual image of the surface before laser thinning. Figure 2 (d) is a microscopic observation before laser thinning, which shows that the surface roughness of polycrystalline diamond is relatively large before laser thinning; Figure 2 (b) is a visual image of the surface after laser thinning. Figure 2 (e) is a microscopic observation after laser thinning. It can be seen that the laser thinning operation can reduce the roughness of the polycrystalline diamond surface and achieve surface flatness; Figure 2 (c) is a visual image of the surface after two-step polishing. Figure 2 (f) is a microscopic observation view after two-step polishing. It can be seen that the surface of the polycrystalline diamond after two-step polishing is relatively smooth and has high flatness. The roughness Ra can reach 0.335nm, and polycrystalline diamond with high surface quality can be obtained.

[0093] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for processing a polycrystalline diamond surface, characterized in that: Includes steps: (1) Using laser to thin the surface of polycrystalline diamond; (2) polishing the surface of the laser-thinned polycrystalline diamond, wherein the polishing liquid comprises, by weight, 0.02 to 0.1 parts of polishing abrasive, 0.02 to 0.1 parts of transition metal powder and 1 part of water, the pH of the polishing liquid is adjusted to 10 to 11 by an alkaline substance, the alkaline substance is selected from at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide, and the polishing abrasive is selected from at least one of diamond, silicon carbide and boron carbide.

2. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: In step (1), the wavelength of the laser is 325 to 532 nm.

3. The method for processing a polycrystalline diamond surface according to claim 2, characterized in that: The power of the laser is 10-50W, the frequency is 6-10kHz, and the moving speed is 200-600mm / min.

4. The method for processing a polycrystalline diamond surface according to claim 2, characterized in that: The laser thinning cutting paths are spaced 10 to 30 μm apart.

5. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: In step (2), the particle size of the polishing abrasive is 0.2 to 1 μm.

6. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: In step (2), the transition metal powder is selected from at least one of iron, cobalt, nickel, copper and manganese; Preferably, the particle size of the transition metal powder is 0.2 to 10 μm.

7. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: In step (2), the flow rate of the polishing liquid during the polishing process is 0.1 to 1 L / min, and the pressure is 100 to 600 g / cm 2 .

8. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: Before the polishing in step (2), the method further includes the step of pre-polishing with a pre-polishing liquid, wherein the pre-polishing liquid comprises diamond powder, hydrogen peroxide and water in a weight ratio of (0.1-0.2):(0.05-0.1):

1.

9. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: The particle size of the diamond powder in the pre-polishing liquid is 0.5-2 μm.

10. The method for processing a polycrystalline diamond surface according to claim 1, characterized in that: The pre-polishing removal thickness is 2-5 μm.

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