A method for reducing the surface roughness of diamond materials

Abstract

This invention relates to a method for reducing the surface roughness of diamond materials. The method involves placing a diamond on a substrate stage within a vacuum chamber; horizontally injecting a laser to determine the processing procedure; introducing a working gas into the vacuum chamber to excite plasma above the diamond; applying a radial magnetic field within the plasma discharge region; adjusting the laser power to high power while simultaneously reciprocating the high-power laser in a horizontal position to execute the processing procedure, thereby removing the thickness required to reduce the diamond surface roughness; stopping the substrate stage; turning off the laser and magnetic field, extinguishing the plasma, cutting off the introduced working gas, venting the chamber, and removing the diamond; checking whether the diamond surface roughness meets the expected requirements; if not, repeating the above steps; if the expected requirements are met, the processing is complete. This method can effectively reduce the surface roughness of diamond, improve processing efficiency, and increase the yield of diamond processing products.

Description

Technical Field

[0001] This invention relates to the field of surface processing of superhard materials, and more specifically to a method for reducing the surface roughness of diamond materials. Background Technology

[0002] Diamond's excellent physical and chemical properties make it popular in a wide range of applications. However, due to its extremely high hardness and good wear resistance, it is very difficult to treat the surface of diamond using traditional processing techniques.

[0003] Generally, the long growth process of polycrystalline diamond films results in large grains and grain boundaries of varying sizes and crystal planes, leading to a high surface roughness. Similarly, after a long period of homoepitaxial growth, the polycrystalline rings formed around single-crystal diamonds also significantly increase the surface roughness of the grown surfaces.

[0004] Laser processing of diamond materials can achieve high efficiency, but diamond materials that have been laser-cut will also have high surface roughness due to the cutting marks on the cut surface.

[0005] Currently, the surface processing of diamond materials mainly adopts mechanical grinding or chemical mechanical grinding. However, these two processing methods are very easy to damage or even crack the diamond materials, and the processing time is long. When facing large-area polycrystalline diamond thick films and batch processing of single-crystal diamonds, the product yield obtained by the above two commonly used processing methods is low. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for reducing the surface roughness of diamond materials, so as to overcome the shortcomings of the prior art.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A method for reducing the surface roughness of diamond materials, comprising the following steps:

[0008] S1. Place the diamond on the substrate stage in the vacuum chamber;

[0009] S2. Horizontal laser injection to determine the processing procedure;

[0010] S3. Introduce working gas into the vacuum chamber to excite plasma above the diamond.

[0011] S4. Apply a radial magnetic field within the plasma discharge region;

[0012] S5. Adjust the laser power to high power, and simultaneously move the high-power laser back and forth in a horizontal position to execute the processing procedure so that the diamond is removed to reduce the thickness required to reduce the surface roughness of the diamond, and stop the substrate stage.

[0013] S6. Turn off the laser and radial magnetic field, extinguish the plasma, cut off the incoming working gas, vent the cavity, and remove the diamond;

[0014] S7. Check whether the surface roughness of the diamond meets the expected requirements. If it does not meet the expected requirements, repeat S1 to S6. If it meets the expected requirements, the processing ends.

[0015] Based on the above technical solution, the present invention can be further improved as follows.

[0016] Furthermore, the method for determining the processing technology is as follows:

[0017] Set the initial position of the substrate stage;

[0018] The diamond is positioned axially by adjusting the substrate stage so that the highest point of the diamond surface comes into contact with the laser.

[0019] Continue to raise the diamond axially through the substrate stage until the height the diamond continues to rise is equal to the thickness that needs to be removed to reduce the surface roughness of the diamond, and then reset the substrate stage.

[0020] Set the entire process as a processing procedure, and set the processing time and substrate stage rise rate.

[0021] Furthermore, it was determined that the laser used in the processing was a 10-150mW milliwatt-level laser.

[0022] Furthermore, the intensity of the applied radial magnetic field is 600-1500 GS.

[0023] Furthermore, high-power lasers are watt-level lasers ranging from 10 to 150W.

[0024] Furthermore, the working gas is a gas that can produce an etching effect on diamond or graphite.

[0025] Furthermore, the working gas is hydrogen, oxygen, or a mixture of hydrogen and oxygen.

[0026] Furthermore, in step S3, the plasma is excited by microwaves, radio frequency, or DC.

[0027] Furthermore, in step S4, the radial magnetic field is provided by a permanent magnet or a magnetic field coil.

[0028] The beneficial effects of this invention are as follows:

[0029] By combining the ablation effect of laser on diamond and the etching effect of plasma on diamond, efficient processing of diamond surface can be achieved.

[0030] By using magnetic field configuration to control the direction of the plasma-activated working gas acting on the diamond surface, and simultaneously adjusting the axial displacement of the substrate stage to control the thickness of the diamond processing layer and the processing time, precise control of the diamond surface roughness can be achieved.

[0031] This method can be used for surface processing of large-area diamond thick films and batch processing of single-crystal diamond surfaces, effectively improving the efficiency of diamond material surface processing, increasing the yield of diamond processing, and is simple to operate. Attached Figure Description

[0032] Figure 1 A schematic diagram of the processing apparatus involved in this invention;

[0033] Figure 2 This is a front view of the processing apparatus involved in Example 1;

[0034] Figure 3 This is a top view of the processing apparatus involved in Example 1;

[0035] Figure 4 This is a front view of the processing apparatus involved in Example 2;

[0036] Figure 5 This is a top view of the processing apparatus involved in Example 2.

[0037] In the diagram, 1 is the substrate stage; 2 is the radial magnetic field; 3 is the vacuum cavity; 4 is the laser; 5 is the working gas; 6 is the plasma; 7 is the diamond; and 8 is the observation window. Detailed Implementation

[0038] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0039] like Figure 1 As shown, a method for reducing the surface roughness of diamond materials includes the following steps:

[0040] S1. Place the diamond 7 on the substrate stage 1 in the vacuum chamber 3 and evacuate the vacuum chamber 3.

[0041] S2. Horizontally inject low-power laser 4. Typically, the laser can be a single laser beam or multiple laser beams. The laser beam paths can be parallel or intersecting. Adjust the position of diamond 7 in the axial direction through the substrate stage 1 so that the highest point of the diamond 7 surface contacts the low-power laser 4. Set the position of diamond 7 in the axial direction at this time as position a.

[0042] S3. Continue to raise the diamond 7 slightly in the axial direction through the substrate stage 1 to determine the thickness that needs to be removed to reduce the surface roughness of the diamond 7, and set the position of the diamond 7 in the axial direction at this time as position b, where the height difference between position b and position a is equal to the thickness that needs to be removed to reduce the surface roughness of the diamond 7, and then adjust the substrate stage 1 to the initial position.

[0043] S4. The process of raising diamond 7 from position a to position b is defined as one processing process. The time of one processing process and the raising rate of substrate stage 1 are set.

[0044] S5. Introduce working gas 5 into vacuum chamber 3 to excite plasma 6 above diamond 7.

[0045] S6. Apply a radial magnetic field 2 within the plasma 6 discharge region, typically a radial magnetic field of 600-1500GS.

[0046] S7. Upgrade the horizontally incident low-power laser to a high-power laser. Typically, the laser can be a single laser beam or multiple laser beams. The laser beam paths can be parallel or intersecting. Also, the high-power laser 4 is moved back and forth in a horizontal position, and the total amount of back and forth movement covers the area to be processed.

[0047] S8. Using the substrate stage 1, the diamond 7 is raised from the initial position to position a to start one processing cycle. The process continues until the diamond 7 is raised to position b to complete one processing cycle. Then, the substrate stage 1 is stopped.

[0048] S9. Turn off laser 4 and radial magnetic field 2, extinguish plasma 6, cut off the incoming working gas 5, vent the cavity to atmospheric pressure, and take out diamond 7.

[0049] S10. Check whether the surface roughness of diamond 7 meets the expected requirements. If it does not meet the expected requirements, repeat S1 to S9. If it meets the expected requirements, the processing ends.

[0050] Example 1

[0051] like Figure 2 , Figure 3 As shown, a method for reducing the surface roughness of diamond materials requires reducing the surface roughness of a 70mm diameter diamond 7 (the diamond 7 is a polycrystalline diamond) to below 50nm. The following steps are used to reduce the surface roughness of the 70mm diameter diamond 7 (the diamond 7 is a polycrystalline diamond):

[0052] Step S1: Place the diamond 7 with a diameter of 70mm on the substrate stage 1 in the vacuum chamber 3, set the initial position of the diamond 7 to 0mm, and evacuate the vacuum chamber 3 to 0.5kPa.

[0053] Step S2: A horizontal 10mW laser 4 is injected through the observation window 8. The substrate stage 1 is raised so that the highest point of the surface of the 70mm diameter diamond 7 comes into contact with the laser 4. The position of the diamond 7 in the axial direction is set to 3mm at this time.

[0054] Step S3: Continue to raise the diamond 7 slightly in the axial direction using the substrate stage 1 to determine the thickness that needs to be removed to reduce the surface roughness of the diamond 7, and set the position of the diamond 7 in the axial direction at this time to 3.2mm. Then adjust the substrate stage 1 to the initial position.

[0055] Step S4: The process of raising the diamond 7 from 3.0mm to 3.2mm is set as one processing process. The time of one processing process is set to ≥20min, and the lifting rate of the substrate stage 1 is ≤0.01 mm / min.

[0056] Step S5: Introduce a hydrogen-oxygen mixture with a volume ratio of 300:1 into the vacuum chamber 3, and input 1000W microwaves to excite plasma 6 above the diamond 7.

[0057] Step S6: Apply a radial magnetic field 2 with a magnetic field strength of 860 Gs to the plasma 6 discharge region. The radial magnetic field 2 is generated by a permanent magnet ring.

[0058] Step S7: Increase the power of laser 4 to 100W and make laser 4 reciprocate in a horizontal position with a displacement of 75mm;

[0059] Step 8: Raise the substrate stage 1 at a constant speed of 0.01 mm / min from the initial position to 3.0 mm to start one processing cycle. Continue until the diamond 7 is raised to 3.2 mm to complete one processing cycle, and then stop the substrate stage 1.

[0060] Step S9: Turn off laser 4, remove the set permanent magnet, stop the microwave input to extinguish plasma 6, cut off the incoming hydrogen-oxygen mixture, vent the cavity to atmospheric pressure, and take out the diamond 7 with a diameter of 70mm.

[0061] Step S10: Inspect the surface roughness of diamond 7 after one processing step. After one processing step, the surface roughness of diamond 7 with a diameter of 70mm is 45nm, which meets the predetermined requirements and the processing is completed.

[0062] Example 2

[0063] like Figure 4 , Figure 5 As shown, a method for reducing the surface roughness of diamond materials involves using 13 7×7mm diamond sheets. 2 The surface roughness of diamond 7 (which is a single-crystal diamond) was reduced to below 40 nm by the following steps: reducing the surface roughness of three 7×7 mm diamond sheets. 2 The surface roughness of diamond 7 (the diamond 7 is a single crystal diamond);

[0064] Step S1: Place 13 pieces of 7×7mm... 2 Diamond 7 is placed on substrate stage 1 in vacuum chamber 3, the initial position of diamond 7 is set to 0mm, and vacuum chamber 3 is evacuated to 0.3kPa.

[0065] Step S2: A horizontal 100mW laser 4 is injected through the observation window 8, causing the substrate stage 1 to hold 13 7×7mm substrates. 2 The highest point of diamond 7 comes into contact with laser 4, and the position of diamond 7 in the axial direction is set to 2mm at this time;

[0066] Step S3: Continue to raise the diamond 7 slightly in the axial direction using the substrate stage 1 to determine the thickness that needs to be removed to reduce the surface roughness of the diamond 7, and set the position of the diamond 7 in the axial direction at this time to 2.2mm. Then adjust the substrate stage 1 to the initial position.

[0067] Step S4: The process of raising the diamond 7 from 2.0mm to 2.2mm is set as one processing process. The time of one processing process is set to be ≥20min, and the lifting rate of the substrate stage 1 is ≤0.01mm / min.

[0068] Step S5: Introduce 20 sccm of oxygen into the vacuum chamber 3 as working gas 5, and input 1500W of microwaves to excite plasma 6 above the diamond 7.

[0069] Step S6: Apply a radial magnetic field 2 with a magnetic field strength of 1400 Gs to the plasma 6 discharge region. The radial magnetic field 2 is generated by a magnetic field coil.

[0070] Step S7: Increase the power of laser 4 to 100W, control the number of lasers 4 to 5 with a spacing of 10mm, and make each laser 4 reciprocate with a displacement of 15mm in the horizontal position.

[0071] Step 8: Raise the substrate stage 1 from the initial position to the diamond 7 to 2.0 mm at a constant speed of 0.003 mm / min to start one processing cycle. Continue until the diamond 7 is raised to 2.2 mm to complete one processing cycle, and then stop the substrate stage 1.

[0072] Step 9: Turn off laser 4, disconnect the power supply to the radial magnetic field 2 coil, remove radial magnetic field 2, stop the microwave input to extinguish plasma 6, cut off the oxygen supply, vent the cavity to atmospheric pressure, and remove 13 pieces of 7×7mm. 2 Diamond 7;

[0073] Step 10: Inspect the 13 pieces of 7×7mm after one processing step. 2 The surface roughness of diamond 7, after one machining, is 13 pieces of 7×7mm. 2 The surface roughness of diamond 7 was 70 nm, which did not meet the predetermined requirements. Steps S1-S9 were repeated, and after 5 processing steps, 13 pieces of 7×7 mm diamond were produced. 2 The surface roughness of diamond 7 is less than 40nm, and the processing is completed.

[0074] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for reducing the surface roughness of diamond materials, characterized in that, Includes the following steps: S1. Place the diamond on the substrate stage in the vacuum chamber; S2. Horizontal laser injection to determine the processing procedure; S3. Introduce working gas into the vacuum chamber to excite plasma above the diamond. S4. Apply a radial magnetic field within the plasma discharge region; S5. Adjust the laser power to high power, and simultaneously move the high-power laser back and forth in a horizontal position to execute the processing procedure so that the diamond is removed to reduce the thickness required to reduce the surface roughness of the diamond, and stop the substrate stage. S6. Turn off the laser and radial magnetic field, extinguish the plasma, cut off the incoming working gas, vent the cavity, and remove the diamond; S7. Check whether the surface roughness of the diamond meets the expected requirements. If it does not meet the expected requirements, repeat S1 to S6. If it meets the expected requirements, the processing ends.

2. The method for reducing the surface roughness of diamond materials according to claim 1, characterized in that: The method for determining the processing technology is as follows: Set the initial position of the substrate stage; The diamond is positioned axially by adjusting the substrate stage so that the highest point of the diamond surface comes into contact with the laser. Continue to raise the diamond axially through the substrate stage until the height the diamond continues to rise is equal to the thickness that needs to be removed to reduce the surface roughness of the diamond, and then reset the substrate stage. Set the entire process as a processing procedure, and set the processing time and substrate stage rise rate.

3. The method for reducing the surface roughness of diamond materials according to claim 2, characterized in that: The laser used in the processing procedure is determined to be a 10-150mW milliwatt-level laser.

4. The method for reducing the surface roughness of diamond materials according to claim 1, characterized in that: The high-power laser is a watt-level laser of 10-150W.

5. The method for reducing the surface roughness of diamond materials according to claim 1, characterized in that: The working gas is a gas that can produce an etching effect on diamond or graphite.

6. The method for reducing the surface roughness of diamond materials according to claim 5, characterized in that: The working gas is hydrogen, oxygen, or a mixture of hydrogen and oxygen.

7. The method for reducing the surface roughness of diamond materials according to claim 1, characterized in that: In step S3, the plasma is excited by microwaves, radio frequency, or direct current.

8. The method for reducing the surface roughness of diamond materials according to claim 1, characterized in that: In step S4, the radial magnetic field is provided by a permanent magnet or a magnetic field coil.

Images