Large-area CVD diamond film polishing method and polishing device

Abstract

A large-area CVD diamond film polishing method comprises the following steps that S1, groove edges of a diamond film produced through an electric arc method are cut off, and the surface roughness Sa0 of the diamond film is reduced to 200 nm or below after surface grinding; s2, pre-polishing is conducted, specifically, the diamond film treated in the step S1 is fixed to a substrate and then fixed to self-assembly polishing equipment, rapid pre-polishing is conducted through a small polyurethane polishing head, and the surface roughness Sa1 of the pre-polished diamond film is integrally, evenly and rapidly reduced to be smaller than 20 nm; and S3, fine polishing is conducted, specifically, an oval glass polishing head is replaced, the diamond film subjected to pre-polishing treatment in the step S2 is further polished, the surface roughness Sa2 is smaller than 2 nm, and polishing is completed. The small polishing head is used for polishing the diamond film, and the technical problems of low efficiency and non-uniformity in the large-area diamond film polishing process are effectively solved.

Description

Technical Field

[0001] The invention relates to a large-area CVD diamond film polishing method and a polishing device, belonging to the technical field of diamonds. Background Art

[0002] CVD diamond film is a polycrystalline pure diamond without any binder. It has high hardness, electrical insulation, wide light transmission band and chemical inertness comparable to natural diamond. It is regarded as the most promising engineering material in the 21st century and has a wide range of application prospects. However, due to the inherent defects of CVD diamond growth, its growth surface is very rough and the dimensional tolerance is relatively large. It cannot be used directly and must be ground and polished to reduce the surface roughness and dimensional tolerance of the diamond film.

[0003] Existing CVD diamond film processing methods include mechanical polishing, laser, ion beam processing, friction chemical polishing, chemical mechanical polishing, etc. Among them, mechanical polishing still occupies a dominant position and is still the most effective processing method in terms of processing efficiency and polishing effect. However, in the current mechanical processing process, the diamond film is mostly placed on a larger polishing disk, pressure and polishing liquid are applied, and the polishing disk rotates to mechanically polish the diamond film. This processing method usually requires the use of megapascal polishing pressure. The polishing pressure is high and the pressure in different areas of the diamond film is different due to problems such as uneven surface shape of the diamond film, uneven distribution of powder, or poor operation of the diamond film due to the gradual smoothness of the polishing disk surface during processing, resulting in different pressures and removal rates in different areas of the diamond film, resulting in inconsistent surface roughness. Summary of the invention

[0004] In order to overcome the drawbacks of the prior art, the present invention provides a large-area CVD diamond film polishing method and polishing device, which utilizes a small polishing head to polish the diamond film, and effectively solves the technical problems of low efficiency and unevenness in the large-area diamond film polishing process.

[0005] The technical solution adopted by the present invention to solve its technical problem is: A large-area CVD diamond film polishing method, the method comprising the following steps: S1, cutting the groove edge of the diamond film produced by the arc method, and reducing the surface roughness Sa of the diamond film to less than 200nm after surface grinding; S2, pre-polishing: fix the diamond film processed in step S1 on a substrate, and then fix it on a self-assembled polishing device, first use a small polyurethane polishing head for rapid pre-polishing, and the surface roughness Sa of the diamond film after pre-polishing is uniformly and quickly reduced to 20nm overall; S3, fine polishing: replace the elliptical glass polishing head, and further polish the diamond film pre-polished in step S2 to reduce the surface roughness Sa to 1 nm, and then complete the polishing.

[0006] In the above large-area CVD diamond film polishing method, in step S1, the surface grinding process is rough grinding and fine grinding of the diamond film on a grinder, the grinding time for rough grinding and fine grinding is 4 hours, and the grinding pressure is 30N.

[0007] In the above large-area CVD diamond film polishing method, in the step S2, the polishing liquid in the pre-polishing process contains diamond micropowder with a particle size of 0-10 μm, the polishing head load is 30-50N, the polishing head speed is 500-1000 rpm, and the polishing head runs from the center to the edge of the diamond and then reverses back in an Archimedean spiral path.

[0008] In the above large-area CVD diamond film polishing method, in step S3, the polishing liquid in the fine polishing process contains diamond micropowder with a particle size of 0-10 μm, the polishing head load is 30-50N, the polishing head speed is 500-1000 rpm, and the polishing head runs from the center to the edge of the diamond and then reverses back in an Archimedean spiral path.

[0009] A large-area CVD diamond film polishing device, which is used in the above-mentioned large-area CVD diamond film polishing method, and the device includes a movable platform, a movable polishing seat, a polishing spindle, a polishing head, a transmission device and a support frame, the support frame includes a first support frame and a second support frame, the second support frame is horizontally arranged, and the first support frame is provided with two, which are respectively vertically arranged on both sides of one end of the second support frame, the transmission device includes a transverse transmission mechanism and a longitudinal transmission mechanism, the transverse transmission mechanism is arranged at the top ends of the two first support frames, the movable polishing seat is arranged between the two first support frames, one end of which is connected to the transverse transmission mechanism, the polishing spindle is passed through the other end of the movable polishing seat through a shaft sleeve, the top end of the polishing spindle is connected to the first motor, the polishing head is connected to the bottom of the polishing spindle, the longitudinal transmission mechanism is arranged on the second support frame, the movable platform is horizontally arranged on the second support frame, and is connected to the longitudinal transmission mechanism, and the diamond film bonded to the substrate is fixed on the movable platform.

[0010] The above-mentioned large-area CVD diamond film polishing device, the lateral transmission mechanism includes a second motor, a first transmission screw and a first screw nut, the second motor is fixed on the outer side of one of the first support frames, the two ends of the first transmission screw are respectively connected to the two first support frames through bearing structures, and one end passes through the first support frame to be connected to the second motor, the first screw nut is fixed inside the movable polishing seat, and is threadedly connected to the first transmission screw.

[0011] In the above-mentioned large-area CVD diamond film polishing device, a guide rod is also fixed between the two first support frames, the guide rod passes through the movable polishing seat, and the movable polishing seat slides along the guide rod.

[0012] The above-mentioned large-area CVD diamond film polishing device, the longitudinal transmission mechanism includes a second motor, a second transmission screw and a second screw nut, the second motor is fixed at one end of the second support frame, the second transmission screw is longitudinally arranged on the second support frame, the two are connected by a bearing structure, one end of the second transmission screw is connected to the second motor, the second screw nut is fixed at the center position of the bottom surface of the movable platform, and the second screw nut is threadedly connected to the second transmission screw.

[0013] In the above-mentioned large-area CVD diamond film polishing device, slide rails are also longitudinally arranged on the second support frame, respectively arranged on both sides of the second transmission screw, and sliders are fixed on the bottom surface of the movable platform, and the sliders are slidably connected to the slide rails.

[0014] The beneficial effects of the present invention are: The present invention uses a small polishing head to polish a diamond film, which can effectively solve the problems of uneven surface roughness and low polishing efficiency in traditional polishing, especially in large-area polishing. The present invention uses a small polishing head to polish a diamond film, and the pressure of the polishing head is greatly reduced, requiring only 30-50N, which is much less than the pressure of the traditional megapascal level. The polishing head of a polyurethane material is first used to pre-polish the surface of the diamond film, which can quickly and evenly reduce the surface roughness of the diamond film to less than 20nm, and then a glass polishing head is used for fine polishing, so that the surface of the diamond film is uniform and the roughness is as small as about 1nm. The present invention sets the polishing head to perform continuous polishing in a route similar to the Archimedean spiral, so that the polishing is more comprehensive and uniform, and the polishing efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the polishing device of the present invention; Figure 2 It is a schematic diagram of the end structure of the mobile platform; Figure 3The zygo profilometer test results of three points on the edge of the center ring after grinding the CVD diamond film in Example 1 (measurement range 868.758*868.758μm); Figure 4 The zygo profilometer test results of three points on the edge of the center ring after pre-polishing of the CVD diamond film in Example 1 (measurement range 868.758*868.758μm); Figure 5 The zygo profilometer test results of three points on the edge of the center ring of the CVD diamond film after fine polishing in Example 1 (measurement range 868.758*868.758μm); Figure 6 This is a real picture of the CVD diamond film after polishing.

[0016] In the figure: 1. Mobile platform; 2. Mobile polishing seat; 3. Polishing head; 4. Support frame; 4-1. First support frame; 4-2. Second support frame; 5. Transverse transmission mechanism; 5-1. Second motor; 5-2. First transmission screw; 6. Longitudinal transmission mechanism; 6-1. Third motor; 6-2. Second transmission screw; 6-3. Second screw nut; 7. First motor; 8. Guide rod; 9. Slide rail; 10. Slider. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the embodiments.

[0018] See also Figure 1 and Figure 2The polishing of the large-area CVD diamond film of the present invention is performed by using a self-assembled polishing device. The polishing device includes a moving platform 1, a moving polishing seat 2, a polishing spindle, a polishing head 3, a transmission device and a support frame 4, wherein the support frame 4 includes a first support frame 4-1 and a second support frame 4-2, wherein the second support frame 4-2 is horizontally arranged, and the first support frame 4-1 is provided with two, which are respectively vertically arranged on both sides of one end of the second support frame 4-2, and the transmission device includes a transverse transmission mechanism 5 and a longitudinal transmission mechanism 6, wherein the transverse transmission mechanism 5 is arranged at the top of the two first support frames 4-1, and the moving polishing seat 2 is arranged between the two first support frames through the transverse transmission mechanism and the guide rod 3, and the transverse transmission mechanism It includes a second motor 5-1, a first transmission screw 5-2 and a first screw nut. The second motor 5-1 is fixed on the outer side of one of the first support frames 4-1. The two ends of the first transmission screw 5-2 are respectively connected to the two first support frames 4-1 through bearing structures, and one end passes through the first support frame to be connected to the second motor 5-1. The first screw nut is fixed inside the movable polishing seat 2 and is threadedly connected to the first transmission screw 5-2. When the second motor works, it drives the first transmission screw to rotate, thereby driving the movable polishing seat to move along the axial direction of the first transmission screw. The guide shaft plays a guiding and supporting role.

[0019] The longitudinal transmission mechanism 6 is arranged on the second support frame 4-2, the mobile platform 1 is arranged horizontally on the second support frame and connected to the longitudinal transmission mechanism 6, and the diamond film bonded to the substrate is fixed on the mobile platform 1. The longitudinal transmission mechanism 6 includes a third motor 6-1, a second transmission lead screw 6-2 and a second lead screw nut 6-3. The third motor 6-1 is fixed at one end of the second support frame 4-2, the second transmission lead screw 6-2 is longitudinally arranged on the second support frame 4-2, and the two are connected through a bearing structure. One end of the second transmission lead screw 6-2 is connected to the third motor 6-1, the second lead screw nut 6-3 is fixed at the center of the bottom surface of the mobile platform 1, and the second lead screw nut is threadedly connected to the second transmission lead screw 6-2. The second support frame 4-2 is also longitudinally provided with a slide rail 9, which is respectively arranged on both sides of the second transmission lead screw 6-2. A slider 10 is fixed on the bottom surface of the mobile platform 1, and the slider is slidably connected to the slide rail. The third motor rotates, driving the second transmission lead screw to rotate, thereby driving the mobile platform to move along the axial direction of the second transmission lead screw.

[0020] The polishing spindle is inserted through the other end of the movable polishing seat 2 through a sleeve, the top of the polishing spindle is connected to the first motor 7, and the polishing head 3 is connected to the bottom of the polishing spindle. The polishing head can be replaced. The pre-polishing adopts a polyurethane polishing head, and the fine polishing adopts a glass polishing head. The glass polishing head is set to an elliptical shape to prevent the linear speed difference between the edge and the center of the plane polishing head from gradually becoming convex during use. During polishing, the first motor is started, the polishing head rotates, and the second motor and the third motor rotate at the set speed at the same time, driving the diamond film to move horizontally and longitudinally at the same time, and running from the center to the edge of the diamond film and then reversing back to continuously polish the diamond film in a route similar to the Archimedean spiral. The rotation speed of the second motor and the third motor is set in advance to ensure that the polishing is more comprehensive and avoid the phenomenon of missing polishing. During the polishing process, a powder dispenser is used to provide polishing liquid to the polishing surface, and the flow rate of the polishing liquid is controlled to adjust the powder liquid content on the polishing surface during the polishing process. Example 1

[0021] The CVD diamond film with a diameter of 80 mm produced by DC arc plasma jet chemical vapor deposition was ground on a grinder for 8 h (rough grinding and fine grinding) with a grinding pressure of 30 N. The roughness Sa0 of the center, annular zone and edge after grinding were 135.515 nm (a1), 133.621 nm (b1), 137.625 nm (c1) respectively (see Figure 3 ). The diamond film sample was bonded to the substrate, and then the diamond film and the substrate were fixed together on a moving platform. The diamond film was pre-polished using a polyurethane polishing head with a diameter of 2 cm. The diamond powder contained in the polishing liquid had a particle size of 1 μm, the polishing head speed was 800 rpm, and the polishing head pressure was 50 N. After polishing for 10 hours, the roughness Sa1 of the CVD diamond film center, annular zone, and edge were 18.479 nm (a2), 19.012 nm (b2), and 19.790 nm (c2), respectively (see Figure 4 ). Then, an elliptical glass polishing head was used to finely polish the surface of the diamond film. The particle size of the diamond powder contained in the polishing liquid was 0.5 μm, the polishing head speed was 400 rpm, and the polishing head pressure was 30 N. After polishing for 20 hours, the roughness Sa2 of the CVD diamond film center, annular zone, and edge were 1.339 nm (a3), 1.113 nm (b3), and 1.327 nm (c3), respectively (see Figure 5 ). Example 2

[0022] The CVD diamond film with a diameter of 80 mm produced by DC arc plasma jet chemical vapor deposition was ground on a grinder for 8 hours (rough grinding and fine grinding) with a grinding pressure of 30 N. The roughness Sa0 of the center, ring belt and edge after grinding was 138.232 nm, 137.651 nm and 137.325 nm respectively. The diamond film sample was bonded to the substrate, and then the diamond film and the substrate were fixed on a mobile platform. The diamond film was pre-polished using a polyurethane polishing head with a diameter of 2 cm. The particle size of the diamond powder contained in the polishing liquid was 1 μm, the polishing head speed was 600 rpm, the polishing head pressure was 50 N, and after polishing for 10 hours, the roughness Sa1 of the center, ring belt and edge of the CVD diamond film was 18.850 nm, 18.978 nm and 19.562 nm respectively. The surface of the diamond film was then fine-polished using an elliptical glass polishing head. The diamond powder contained in the polishing liquid had a particle size of 0.5 μm, the polishing head speed was 300 rpm, the polishing head pressure was 30 N, and after polishing for 20 hours, the roughness Sa2 of the center, annulus, and edge of the CVD diamond film were 1.552 nm, 1.497 nm, and 1.492 nm, respectively. Example 3

[0023] The CVD diamond film with a diameter of 80 mm produced by DC arc plasma jet chemical vapor deposition was ground on a grinder for 8 hours (rough grinding and fine grinding) with a grinding pressure of 30 N. After grinding, the roughness Sa0 of the center, annulus, and edge were 133.452 nm, 135.671 nm, and 139.245 nm, respectively. The diamond film sample was bonded to the substrate, and then the diamond film and the substrate were fixed on a mobile platform. The diamond film was first pre-polished using a polyurethane polishing head with a diameter of 2 cm. The particle size of the diamond powder contained in the polishing liquid was 2.5 μm, the polishing head speed was 800 rpm, and the polishing head pressure was 50 N. After polishing for 10 hours, the roughness Sa1 of the center, annulus, and edge of the CVD diamond film were 19.360 nm, 19.752 nm, and 19.800 nm, respectively. The surface of the diamond film was then fine-polished using an elliptical glass polishing head. The diamond powder contained in the polishing liquid had a particle size of 1 μm, the polishing head speed was 400 rpm, the polishing head pressure was 30 N, and after polishing for 20 hours, the roughness Sa2 of the center, annulus, and edge of the CVD diamond film were 1.825 nm, 1.911 nm, and 1.820 nm, respectively.

[0024] The above is only a specific implementation of the present invention, but not all the implementation methods of the present invention. The protection scope of the present invention is not limited to this. Any technician familiar with the field of the present invention can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A large-area CVD diamond film polishing method, characterized in that: The method comprises the following steps: S1, cutting the groove edge of the diamond film produced by the arc method, and reducing the surface roughness Sa0 of the diamond film to less than 200nm after surface grinding; S2, pre-polishing: fix the diamond film processed in step S1 on a substrate, and then fix it on a self-assembled polishing device, first use a small polyurethane polishing head for rapid pre-polishing, and the surface roughness Sa1 of the diamond film after pre-polishing is uniformly and quickly reduced to Sa1<20nm; S3, fine polishing: replace the elliptical glass polishing head, and further polish the diamond film pre-polished in step S2 to obtain a surface roughness Sa2 <2nm, and then complete the polishing.

2. The large-area CVD diamond film polishing method according to claim 1, characterized in that: In the step S1, the surface grinding process is rough grinding and fine grinding of the diamond film on a grinder, the grinding time of rough grinding and fine grinding is 4 hours, and the grinding pressure is 30N.

3. The large-area CVD diamond film polishing method according to claim 1, characterized in that: In the step S2, the polishing liquid in the pre-polishing process contains diamond powder with a particle size of 0-10 μm, the polishing head load is 30-50N, the polishing head speed is 500-1000 rpm, and the polishing head runs from the center to the edge of the diamond and then reverses back in an Archimedean spiral path.

4. The large-area CVD diamond film polishing method according to claim 1, characterized in that: In step S3, the polishing liquid in the fine polishing process contains diamond powder with a particle size of 0-10 μm, the polishing head load is 30-50N, the polishing head speed is 500-1000 rpm, and the polishing head runs from the center to the edge of the diamond and then reverses back in an Archimedean spiral path.

5. A large-area CVD diamond film polishing device, characterized in that: The device is used in the large-area CVD diamond film polishing method described in any one of claims 1 to 4, the device comprising a movable platform (1), a movable polishing seat (2), a polishing spindle, a polishing head (3), a transmission device and a support frame (4), the support frame (4) comprising a first support frame (4-1) and a second support frame (4-2), the second support frame (4-2) being arranged horizontally, two first support frames (4-1) being arranged vertically on both sides of one end of the second support frame (4-2), the transmission device comprising a transverse transmission mechanism (5) and a longitudinal transmission mechanism (6), the transverse transmission mechanism (5) being arranged The movable polishing seat (2) is arranged at the top of the two first support frames (4-1), one end of which is connected to the horizontal transmission mechanism (5), the polishing spindle is inserted through the other end of the movable polishing seat (2) through a shaft sleeve, the top of the polishing spindle is connected to the first motor (7), the polishing head (3) is connected to the bottom of the polishing spindle, the longitudinal transmission mechanism (6) is arranged on the second support frame (4-2), the movable platform (1) is horizontally arranged on the second support frame and connected to the longitudinal transmission mechanism (6), and the diamond film bonded to the substrate is fixed on the movable platform (1).

6. The large-area CVD diamond film polishing device according to claim 5, characterized in that: The transverse transmission mechanism (5) comprises a second motor (5-1), a first transmission lead screw (5-2) and a first lead screw nut; the second motor (5-1) is fixed on the outer side of one of the first support frames (4-1); the first transmission lead screw (5-2) has two ends connected to the two first support frames (4-1) via bearing structures, and one end passes through the first support frame and is connected to the second motor (5-1); the first lead screw nut is fixed inside the movable polishing seat (2) and is threadedly connected to the first transmission lead screw (5-2).

7. The large-area CVD diamond film polishing device according to claim 6, characterized in that: A guide rod (8) is also fixed between the two first support frames (4-1), the guide rod (8) passes through the movable polishing seat (2), and the movable polishing seat slides along the guide rod.

8. The large-area CVD diamond film polishing device according to claim 5, characterized in that: The longitudinal transmission mechanism (6) comprises a third motor (6-1), a second transmission lead screw (6-2) and a second lead screw nut (6-3); the third motor (6-1) is fixed to one end of the second support frame (4-2); the second transmission lead screw (6-2) is longitudinally arranged on the second support frame (4-2); the two are connected via a bearing structure; one end of the second transmission lead screw (6-2) is connected to the third motor (6-1); the second lead screw nut is fixed to the center of the bottom surface of the mobile platform (1); and the second lead screw nut is threadedly connected to the second transmission lead screw (6-2).

9. The large-area CVD diamond film polishing device according to claim 8, characterized in that: The second support frame (4-2) is also provided with slide rails (9) longitudinally, which are respectively arranged on both sides of the second transmission screw (6-2); a slider (10) is fixed on the bottom surface of the mobile platform (1), and the slider is slidably connected to the slide rails.

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