Apparatus and method for promoting high-efficiency polishing of diamond under ultraviolet irradiation at low pressure

Abstract

This application pertains to the field of diamond polishing, specifically disclosing an apparatus and method for promoting efficient diamond polishing under low-pressure ultraviolet irradiation. The apparatus includes a sealed chamber and an upper rotating shaft, a lower rotating shaft, a polishing plate, and an ultraviolet lamp disposed within the sealed chamber. The sealed chamber contains process gas, and the pressure is maintained between 0.2 torr and 2 torr. The lower part of the upper rotating shaft is connected to the diamond to be polished; the upper part of the lower rotating shaft is connected to the polishing plate. The polishing plate is made of a transparent material or a metal material with multiple light-transmitting holes and is in contact with the diamond to be polished. The ultraviolet lamp is disposed below the polishing plate and coaxially arranged with the upper rotating shaft. This application, by irradiating the diamond to be polished with ultraviolet light under low pressure, enables the diamond to be preferentially graphitized to form a soft graphite layer, which is then removed by friction from the polishing plate at room temperature, effectively preventing damage to the diamond.

Description

Technical Field

[0001] This application pertains to the field of diamond polishing, and more specifically, relates to an apparatus and method for promoting efficient polishing of diamonds by ultraviolet irradiation under low pressure. Background Technology

[0002] Diamond possesses excellent mechanical, electrical, thermal, and optical properties, making it a promising candidate for applications in high-tech fields such as mechanics, microelectronics, biomedicine, aerospace, and nuclear energy. However, almost all applications place stringent requirements on the surface quality of diamond, demanding low surface damage and nanoscale surface roughness. The surface quality of diamond significantly impacts the performance and stability of devices, serving as a crucial factor in evaluating the quality of diamond devices. However, diamond's high brittleness, the highest hardness found in nature, and extremely strong chemical stability make surface processing difficult and inefficient. Therefore, developing a method for efficiently and effectively polishing diamond is essential.

[0003] The basic methods for removing diamond materials include: micro-fragmentation through physical and mechanical methods; removal of diamond surface atoms through bonding and adhesion forces; and destruction of the original carbon chain structure of diamond, transforming it into amorphous carbon structures such as graphite, followed by mechanical removal. Based on these material removal methods, diamond polishing currently mainly includes mechanical polishing, thermochemical polishing, triboelectric polishing, chemical mechanical polishing, laser polishing, and ion beam polishing. Although various diamond polishing methods have been proposed, the industrial-scale, high-efficiency, and high-quality polishing technology is not yet perfect. In some high-precision applications, it is required to achieve atomically flat surfaces quickly while minimizing and avoiding surface and subsurface damage, and traditional polishing methods still have many problems.

[0004] The disadvantages of mechanical polishing are that the strong mechanical abrasion can easily cause cracks and damage to the diamond surface; thermochemical polishing requires processing in a high-temperature, closed environment, which can easily lead to thermal deformation of the polishing plate, reduced wear resistance, and unstable polishing; the high-speed rotation and high polishing pressure of dynamic friction polishing may cause the diamond film to crack; chemical mechanical polishing has a high surface quality, but its disadvantages are low processing efficiency and the difficulty in treating corrosive waste liquid, which pollutes the environment; laser polishing has low roughness and surface accuracy after processing and is prone to surface cracking, making it suitable for rough processing; ion beam polishing has high processing precision, but low removal rate, small ion beam area, and is not suitable for polishing large-area diamond processing, and the polishing process requires a high vacuum environment, resulting in high equipment costs. Ultraviolet-assisted polishing technology and plasma-assisted polishing use ultraviolet light or plasma to induce the generation of hydroxyl radicals, and utilize the reaction between hydroxyl radicals and the diamond surface to remove material. CN117681064A discloses a method and apparatus for rapid diamond polishing based on ultraviolet light. It combines mechanical polishing and chemical oxidation polishing in an atmospheric environment, using oxygen supplied by an ultraviolet unit and an oxygen supply unit to generate oxygen free radicals and ozone. These, combined with a polishing slurry, modify the diamond surface, thereby increasing the polishing speed. CN118456249A discloses a method and apparatus for ultraviolet light-vibration-assisted polishing of diamond substrates. This method uses ultrasonic vibration to assist polishing of diamond under ultraviolet light irradiation. The diamond material is mainly removed through the stress and high temperature generated by vibration excitation on the surface to be processed. The ultraviolet light source is placed outside the vacuum chamber, and because it is blocked by the atmosphere, its role in polishing is very limited. This technology, combining multiple energy fields, suffers from complex processes and difficult control, and can lead to damage or even breakage of the diamond due to high temperature and stress. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides an apparatus and method for promoting efficient polishing of diamonds by ultraviolet irradiation under low pressure, aiming to solve the problem that existing ultraviolet-assisted polishing technologies require the combination of other auxiliary means.

[0006] According to one aspect of this application, an apparatus for promoting efficient polishing of diamond under low-pressure ultraviolet irradiation is provided. Specifically, it includes a sealed chamber and an upper rotating shaft, a lower rotating shaft, a polishing plate, and an ultraviolet lamp disposed within the sealed chamber. The sealed chamber contains process gas and maintains a pressure of 0.2 torr to 2 torr. The lower part of the upper rotating shaft is connected to the diamond to be polished to drive its rotation. The upper part of the lower rotating shaft is connected to the polishing plate to drive its rotation. The polishing plate is made of a transparent material or a metal material with multiple light-transmitting holes and contacts the diamond to achieve friction polishing. The ultraviolet lamp is disposed below the polishing plate and coaxially with the upper rotating shaft, emitting ultraviolet light that passes through the polishing plate and irradiates the polishing surface of the diamond to be polished, thereby promoting the formation of a soft graphite layer on the polishing surface of the diamond to facilitate polishing.

[0007] Compared with the prior art, the technical solution conceived in this application can effectively improve polishing efficiency by using ultraviolet light to irradiate diamond under low pressure, and can effectively avoid damage to diamond without the need for other auxiliary means.

[0008] As a further preferred embodiment, the process gas is one or more of O2, CH4, Cl2, CF4, and SF6.

[0009] As a further preferred embodiment, the ultraviolet light emitted by the ultraviolet lamp has a wavelength of 172 nm.

[0010] As a further preferred embodiment, the sealed chamber is provided with an air inlet and an air outlet. The air inlet is used to connect to a process gas pipeline to introduce process gas, and the air outlet is connected to a vacuum pump through an exhaust valve to adjust the exhaust rate of the sealed chamber, thereby coordinating with the air inlet rate to maintain the gas pressure in the sealed chamber at 0.2 torr to 2 torr.

[0011] As a further preferred embodiment, a pressure sensor is provided on the upper rotating shaft for measuring the pressure applied to the diamond to be ground.

[0012] As a further preferred embodiment, the polishing plate is made of fused silica, synthetic silica, sapphire, iron-nickel transition metal, or alumina ceramic.

[0013] According to another aspect of this application, a method for diamond polishing using the above-described apparatus is provided, the method specifically comprising:

[0014] S1 fixes the diamond to be ground at the lower end of the upper rotating shaft;

[0015] S2 evacuates the sealed chamber, and then introduces process gas to maintain the gas pressure in the sealed chamber at 0.2 torr to 2 torr;

[0016] S3 turns on the ultraviolet lamp so that ultraviolet light passes through the polishing plate and shines on the diamond to be polished, causing a soft graphite layer to be formed on the polished surface of the diamond.

[0017] S4 uses a lower rotating shaft to drive the polishing plate to rotate, while the upper rotating shaft drives the diamond to be polished to rotate. By controlling the up and down movement of the upper rotating shaft, the pressure applied to the diamond to be polished is adjusted, thereby removing the soft graphite layer on the polished surface through friction, thus achieving diamond polishing.

[0018] As a further preferred embodiment, in step S2, the process gas is one or more of O2, CH4, Cl2, CF4 and SF6, and the flow rate of the process gas is 100 sccm to 1000 sccm.

[0019] As a further preferred embodiment, the wavelength of the ultraviolet light is 172 nm.

[0020] As a further preferred embodiment, in step S4, the rotational speed of the lower rotating shaft is 100 rpm to 500 rpm, the rotational speed of the upper rotating shaft is 10 rpm to 50 rpm, and the pressure applied to the diamond to be ground is 1 N to 20 N.

[0021] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0022] 1. This application utilizes ultraviolet light to irradiate the diamond to be ground under low pressure, which not only excites the diamond but also generates O, a highly oxidizing agent. In addition to ozone, a strong oxidizing atmosphere is formed, which makes the C atoms on the protruding parts of the diamond polishing surface more active, preferentially graphitized to form a soft graphite layer, which is then removed by the polishing plate at room temperature, ultimately forming a sub-nanometer ultra-smooth surface. This process does not require the use of other auxiliary methods, which not only simplifies the process and equipment structure, but also effectively avoids damage to the diamond.

[0023] 2. In particular, by optimizing the wavelength of ultraviolet light emitted by the ultraviolet lamp, this application can avoid ultraviolet light attenuation when combined with low air pressure, and can also stimulate diamond to generate holes and electron pairs, greatly promoting its chemical reaction, and making it easier to transform into graphite when combined with a strong oxidizing atmosphere.

[0024] 3. In addition, this application also optimizes the rotational speed of the lower rotating shaft, the rotational speed of the upper rotating shaft, and the pressure applied to the diamond to be polished, so as to achieve efficient and stable polishing in combination with air pressure and ultraviolet wavelength, and avoid diamond breakage while ensuring polishing effect. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device structure for promoting efficient diamond polishing under low pressure by ultraviolet irradiation, provided in an embodiment of this application.

[0026] Figure 2 This is a white light interference pattern of the diamond after polishing in Embodiment 1 of this application;

[0027] Figure 3 This is a white light interference pattern of the polished diamond in Embodiment 2 of this application;

[0028] Figure 4 This is a white light interference pattern of the diamond after polishing in Embodiment 3 of this application;

[0029] Figure 5 This is a white light interference pattern of the polished diamond in Embodiment 4 of this application;

[0030] Figure 6 This is a white light interference pattern of the polished diamond in Embodiment 5 of this application;

[0031] Figure 7 This is a white light interference pattern of the polished diamond in Embodiment 6 of this application;

[0032] Figure 8 This is a white light interference pattern of the polished diamond in Embodiment 7 of this application;

[0033] Figure 9 This is a white light interference pattern of the polished diamond in Comparative Example 1 of this application;

[0034] Figure 10 This is the white light interference pattern of the polished diamond in Comparative Example 2 of this application;

[0035] Figure 11 This is the white light interference pattern of the polished diamond in Comparative Example 3 of this application;

[0036] Figure 12 This is a Raman image of the diamond surface after polishing in Embodiment 1 of this application;

[0037] Figure 13 It is the temperature curve of the diamond and the inside of the cavity during the polishing process.

[0038] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0039] 1-Air inlet, 2-Sealed chamber, 3-Polishing plate, 4-Lower rotating shaft, 5-Ultraviolet lamp, 6-Diamond to be ground, 7-Exhaust port, 8-Upper rotating shaft. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] like Figure 1 As shown, this application provides an apparatus for promoting efficient polishing of diamonds under low-pressure ultraviolet irradiation. Specifically, it includes a sealed chamber 2 and an upper rotating shaft 8, a lower rotating shaft 4, a polishing plate 3, and an ultraviolet lamp 5 disposed inside the sealed chamber 2. The sealed chamber 2 contains process gas, and the pressure is maintained between 0.2 torr and 2 torr. When the pressure is too high, the gas molecules significantly block ultraviolet light, affecting the intensity of ultraviolet irradiation. Simultaneously, at higher oxygen concentrations, the oxygen free radicals generated by ultraviolet ionization combine with other molecules, reducing their concentration and decreasing the oxidizing power of the atmosphere. Conversely, when the pressure is too low, the oxygen concentration is too low, limiting the generation of oxygen free radicals and reducing the oxidizing power of the gas atmosphere inside the chamber. The sealed chamber 2 is provided with an inlet 1 and an outlet 7. The inlet 1 is connected to a process gas pipeline to introduce process gas, and the outlet 7 is connected to a vacuum pump via an exhaust valve to adjust the exhaust rate of the sealed chamber 2, thereby coordinating with the inlet rate to maintain the pressure of the sealed chamber 2 between 0.2 torr and 2 torr.

[0042] The lower part of the upper rotating shaft 8 is used to connect with the diamond 6 to be ground, so as to drive the diamond 6 to be ground to rotate. The upper part of the lower rotating shaft 4 is connected to the polishing plate 3, so as to drive the polishing plate 3 to rotate. The contact surface between the diamond 6 to be ground and the polishing plate 3 is the polishing surface. By the contact between the polishing plate 3 and the diamond 6 to be ground and the relative rotation, the friction polishing of the polishing surface can be achieved. At the same time, the upper rotating shaft 8 can move up and down in the vertical direction to control the separation or contact between the diamond 6 to be ground and the polishing plate 3, and apply a certain pressure.

[0043] The polishing plate 3 is made of transparent material or metal material with multiple light-transmitting holes. The ultraviolet lamp 5 is set below the polishing plate 3 and coaxial with the upper rotating shaft 8. The lamp tube of the ultraviolet lamp 5 faces upward and is used to emit ultraviolet rays and make them pass through the polishing plate 3 to irradiate the polishing surface of the diamond 6 to be polished, thereby promoting the formation of a soft graphite layer on the polishing surface of the diamond 6 to be polished. The soft graphite layer has low hardness, so it can be removed by low-pressure friction polishing, thereby achieving efficient and non-destructive polishing of the diamond.

[0044] Furthermore, the process gas is one or more of O2, CH4, Cl2, CF4, and SF6, with a purity of 99.99%. The gas pressure in the sealed chamber 2 is further preferably 0.7 torr to 1 torr. A suitable low-pressure environment can greatly promote the graphitization degree of the diamond surface and improve the polishing efficiency.

[0045] Furthermore, the ultraviolet light emitted by the ultraviolet lamp 5 has a wavelength of 172nm. This application uses 172nm excimer ultraviolet light to promote efficient polishing of diamond using a polishing plate. Under atmospheric conditions, 172nm excimer ultraviolet light is absorbed by molecules in the atmosphere and decays rapidly, limiting the irradiation distance to within 3mm. However, under low-pressure conditions, 172nm excimer ultraviolet light does not decay easily, resulting in stronger irradiation intensity and a longer irradiation distance. Diamond has a band gap energy of 5.5eV. Directly irradiating the diamond polishing contact surface with 172nm (7.2eV) excimer ultraviolet light can excite the diamond to generate electron-hole pairs, greatly promoting chemical reactions.

[0046] The power cord and heat dissipation device of the ultraviolet lamp 5 are located outside the sealed chamber 2 and placed in the atmospheric environment, thereby simplifying the device structure of the sealed chamber 2. The light source line and water cooling pipe of the ultraviolet lamp 5 realize the conversion from atmospheric to vacuum through the conversion interface, so that the ultraviolet lamp in the low pressure environment is connected to the power supply and water cooling heat dissipation device in the atmospheric environment through the light source line and water cooling pipe.

[0047] Furthermore, a pressure sensor is provided on the upper rotating shaft 8 to measure the pressure applied to the diamond 6 to be ground.

[0048] Furthermore, the polishing plate 3 is made of a "soft material" with a lower hardness than diamond, preferably fused silica, synthetic silica, sapphire, iron-nickel transition metal or alumina ceramic.

[0049] According to another aspect of this application, a method for diamond polishing using the above-described apparatus is provided, the method specifically comprising:

[0050] S1 fixes the diamond sample stage 6 to be ground at the lower end of the upper rotating shaft 8;

[0051] S2 closes the door of the sealed chamber 2, turns on the vacuum pump to evacuate from the exhaust port 7, and then introduces process gas from the inlet port 1. In conjunction with the exhaust valve and the vacuum pump, the gas pressure in the sealed chamber 2 is maintained at 0.2 torr to 2 torr.

[0052] S3 turns on the ultraviolet lamp 5 so that ultraviolet light passes through the polishing plate 3 and shines on the diamond to be polished 6, causing a soft graphite layer to be produced on the polished surface of the diamond to be polished 6.

[0053] S4 uses the lower rotating shaft 4 to drive the polishing plate 3 to rotate, and at the same time uses the upper rotating shaft 8 to drive the diamond to be polished 6 to rotate. By controlling the upper rotating shaft 8 to move up and down, the pressure applied to the diamond to be polished 6 is adjusted, thereby removing the soft graphite layer on the polished surface through friction, thus achieving diamond polishing.

[0054] After polishing is completed, move the upper rotating shaft 8 to separate the diamond to be polished 6 from the polishing plate 3, stop the upper rotating shaft 8 and the lower rotating shaft 4 from rotating, stop the process gas supply, turn off the ultraviolet lamp 5 and open the door of the sealed chamber 2 to take out the polished diamond.

[0055] Furthermore, in step S2, the process gas is a gas capable of processing diamond, preferably one or more of O2, CH4, Cl2, CF4, and SF6, and the flow rate of the process gas is 100 sccm to 1000 sccm. As the only material input to the sealed chamber 2 during the polishing process, no abrasive or polishing fluid is required, thus avoiding pollution of the polishing environment and achieving the purpose of dry, pollution-free polishing.

[0056] Preferably, the air pressure in the sealed chamber 2 is further preferably 0.7 torr to 1 torr. A suitable low-pressure environment can greatly promote the graphitization degree of the diamond surface and improve the polishing efficiency.

[0057] Furthermore, the wavelength of the ultraviolet light is 172nm, and the application proposes using 172nm excimer ultraviolet light to promote efficient polishing of diamond using a polishing plate. Under atmospheric conditions, 172nm excimer ultraviolet light is absorbed by molecules in the atmosphere and decays rapidly, limiting the irradiation distance to within 3mm. However, under low pressure, 172nm excimer ultraviolet light does not decay easily, resulting in stronger irradiation intensity and a longer irradiation distance. Diamond has a band gap energy of 5.5eV. Directly irradiating the diamond polishing contact surface with 172nm (7.2eV) excimer ultraviolet light can excite the diamond to generate electron-hole pairs, greatly promoting chemical reactions.

[0058] Furthermore, in step S4, the rotational speed of the lower rotating shaft 4 is 100 rpm to 500 rpm, preferably 300 rpm to 500 rpm, the rotational speed of the upper rotating shaft 8 is 10 rpm to 50 rpm, and the pressure applied to the diamond 6 to be polished is 1 N to 20 N, preferably 10 N to 15 N. Lower rotational speeds and loads improve the stability of the polishing process, significantly reducing the possibility of sample breakage during polishing. This ensures a high yield and no damage to the sample while rapidly obtaining an atomically smooth surface. When the gas pressure decreases, the gas atmosphere reduces the obstruction of ultraviolet light, enhancing ultraviolet irradiation and increasing the hydrophilicity of the polishing plate and diamond, thereby enhancing mechanical friction and bonding. When the rotational speed increases, the mechanical friction between the diamond and the polishing plate intensifies, but excessively high speeds can cause local temperatures to reach the diamond graphitization temperature, leading to random graphitization of the diamond and a decrease in surface and subsurface quality. Increased pressure intensifies the mechanical friction between the diamond and the polishing plate, but excessively high pressure can cause significant mechanical stress on the diamond, easily resulting in mechanical damage or even breakage. Therefore, rotational speed, pressure, and air pressure all affect the friction and bonding between the diamond and the polishing plate. It is necessary to promote mechanical friction and bonding while ensuring the surface quality of the diamond in order to improve the polishing rate and surface roughness.

[0059] Compared with existing technologies, this application does not require high rotation speed and high load, and can achieve high removal rate under normal temperature and low pressure environment. It has good surface roughness, no damage to the polished surface, and no waste liquid pollution caused by wet polishing.

[0060] 1. High Material Removal Rate: When the process gas is oxygen, the oxygen introduced into the sealed chamber 2, under the irradiation of excimer ultraviolet light, can ionize to generate oxygen free radicals and react to produce ozone, forming a strong oxidizing atmosphere. Combined with the low-pressure environment, diamond is more easily transformed into graphite. Therefore, the high material removal rate of diamond is a combined effect of graphitization and bond removal. Graphite has a very low hardness compared to the diamond phase, making removal simple. Therefore, the high material removal rate is mainly determined by the diamond graphitization rate, resulting in a relatively high removal rate. In the preferred embodiment of this application, the diamond polishing removal rate was measured. Compared with conventional diamond polishing methods, the polishing rate of the low-pressure ultraviolet-assisted polishing technology proposed in this application can reach more than 0.94 micrometers per hour, which is highly efficient. If a higher-power ultraviolet light source is used or the irradiation distance is shortened, the polishing rate will be further improved.

[0061] 2. Good surface roughness: Under low pressure, excimer ultraviolet irradiation excites the diamond polishing surface and forms a strong oxidizing atmosphere. The C atoms of the protruding parts of the diamond surface are more active and are preferentially graphitized. They are then removed by friction from the soft polishing pad at room temperature, ultimately forming a sub-nanometer ultra-smooth surface.

[0062] like Figure 2As shown, with a turntable speed of 300 rpm, oxygen flow rate of 200 sccm, air pressure of 1 torr, shaft pressure of 10 N, and polishing time of 1 hour, the surface roughness Sa of the diamond sample decreased to below 0.3 nm. Therefore, the method proposed in this patent can achieve a smooth surface at the sub-nanometer atomic scale.

[0063] 3. Low surface damage to diamond: The low rotation speed and low load during the polishing process make the polishing process more stable, and the diamond is less prone to breakage. The polishing plates used, such as quartz glass (10.84 GPa) and iron-nickel transition metals (<5 GPa), have a hardness much lower than diamond (80-120 GPa), thus preventing surface damage and non-diamond phase residue after polishing. Figure 13 As shown, Raman spectroscopy after polishing revealed a pure diamond phase on the surface. The temperature of the diamond sample was measured in real-time using a temperature sensor, and the results are as follows. Figure 13 As shown, the diamond temperature is below 150℃, which is far below the high-temperature graphitization temperature of diamond. This proves that ultraviolet-induced graphitization can prevent defects such as graphite nucleation inside the diamond caused by high-temperature graphitization, effectively improve the sample quality, and prevent diamond damage and breakage.

[0064] 4. No environmental pollution or waste: The material input in the sealed chamber during the polishing process is only dry gas with a purity of 99.99%. That is, the polishing is carried out entirely in dry gas, without the need for polishing fluid composed of abrasive particles and chemical reagents. This avoids contamination of the diamond and the processing environment, and no waste liquid is generated.

[0065] The technical solutions provided in this application will be further described below with reference to specific embodiments and comparative examples 1 and 2.

[0066] Example 1

[0067] First, fix the polishing plate 3 on the lower rotating shaft 4, and fix the diamond to be polished 6 on the lower end of the upper rotating shaft 8. Then, close the door of the sealed chamber 2, turn on the vacuum pump, and evacuate to a low pressure. Then, introduce 200 sccm of oxygen into the sealed chamber 2 through the air inlet 1. Adjust the vacuum valve to control the low pressure environment at 1 torr. Turn on the power of the 172nm excimer ultraviolet lamp 5 outside the chamber. The ultraviolet lamp 5 is located below the polishing plate 3 at the friction contact point with the diamond 6, with the lamp tube facing upward. The ultraviolet light 5 passes through the polishing plate 3 and directly irradiates the surface of the diamond 6 in contact with the polishing plate 3, exciting the diamond 6 and generating O with strong oxidizing properties. And ozone, forming a strong oxidizing atmosphere. The polishing plate 3 rotates under the drive of the lower rotating shaft 4, and the upper rotating shaft 8 holding the diamond substrate 6 begins to rotate. Load is applied by controlling the up-and-down movement of the upper rotating shaft 8. The rotation speed of the upper rotating shaft 8 is 300 ppm, and the rotation speed of the lower rotating shaft 4 is 20 rpm. The pressure applied to the diamond 6 to be polished is 10 N, frictionally removing the soft graphite layer from the polished surface. After processing, the upper rotating shaft 8 is moved to separate the diamond substrate 6 from the polishing plate 3. The rotation of the lower rotating shaft 4 and the upper rotating shaft 8 is stopped, the excimer ultraviolet lamp 5 is turned off, the vacuum is broken, the chamber door is opened, and the diamond substrate sample 6 is removed. With the promotion of this method, a high-removal polishing process ultimately yields an atomically undamaged diamond surface. After 1 hour of polishing, the surface roughness is as follows: Figure 2 As shown, the surface roughness Sa of the diamond sample decreased to below 0.3 nm, with a removal rate of 5.8 μm / h.

[0068] Example 2

[0069] Same as in Example 1, except the air pressure is 0.5 torr, the rotation speed of the upper rotating shaft 8 is 20 rpm, the rotation speed of the lower rotating shaft 4 is 300 rpm, the pressure applied to the diamond 6 to be polished is 10 N, and the surface roughness after polishing for 1 hour is as follows. Figure 3 As shown, the surface roughness Sa of the diamond sample decreased to below 0.3 nm, with a removal rate of 8.0 μm / h.

[0070] Example 3

[0071] Same as Example 1, except the air pressure is 2 torr, the rotation speed of the upper rotating shaft 8 is 20 ppm, the rotation speed of the lower rotating shaft 4 is 300 rpm, the pressure applied to the diamond 6 to be polished is 10 N, and the surface roughness after polishing for 1 hour is as follows: Figure 4 As shown, the surface roughness Sa of the diamond sample is 1.59 nm, and the removal rate is 0.79 μm / h.

[0072] Example 4

[0073] Same as Example 1, except the air pressure is 1 torr, the rotation speed of the upper rotating shaft 8 is 20 ppm, the rotation speed of the lower rotating shaft 4 is 200 rpm, the pressure applied to the diamond 6 to be polished is 10 N, and the surface roughness after polishing for 1 hour is as follows: Figure 5 As shown, the surface roughness Sa of the diamond sample is 0.84 nm, and the removal rate is 3.862 μm / h.

[0074] Example 5

[0075] Same as Example 1, except the air pressure is 1 torr, the rotation speed of the upper rotating shaft 8 is 20 ppm, the rotation speed of the lower rotating shaft 4 is 500 rpm, the pressure applied to the diamond 6 to be polished is 10 N, and the surface roughness after polishing for 1 hour is as follows: Figure 6As shown, the surface roughness Sa of the diamond sample is 0.313 nm, and the removal rate is 8.313 μm / h.

[0076] Example 6

[0077] Same as Example 1, except the air pressure is 1 torr, the rotation speed of the upper rotating shaft 8 is 20 ppm, the rotation speed of the lower rotating shaft 4 is 300 rpm, the pressure applied to the diamond 6 to be polished is 1 N, and the surface roughness after polishing for 1 hour is as follows. Figure 7 As shown, the surface roughness Sa of the diamond sample is 0.848 nm, and the removal rate is 0.945 μm / h.

[0078] Example 7

[0079] Same as Example 1, except the air pressure is 1 torr, the rotation speed of the upper rotating shaft 8 is 20 ppm, the rotation speed of the lower rotating shaft 4 is 300 rpm, the pressure applied to the diamond 6 to be polished is 15 N, and the surface roughness after polishing for 1 hour is as follows: Figure 8 As shown, the surface roughness Sa of the diamond sample is 1.109 nm, and the removal rate is 6.525 μm / h.

[0080] Comparative Example 1

[0081] Same as Example 1, except the air pressure is 10 torr, and the surface roughness after polishing for 1 hour is as follows: Figure 9 As shown, the removal rate is 0.01 μm / h, which is close to the effect under atmospheric conditions.

[0082] Comparative Example 2

[0083] Same as Example 1, except that the diamond 6 to be polished was not irradiated with ultraviolet light. After polishing for 1 hour, the surface roughness was as... Figure 10 As shown, after polishing for 1 hour, the surface roughness Sa is about 2 nm, and the removal rate is about 0.08 μm / h.

[0084] Comparative Example 3

[0085] Same as Example 1, except that there is no low-pressure environment, and the sealed chamber 2 is in an atmospheric environment, such as Figure 11 As shown, after polishing for 1 hour, the surface roughness Sa is about 2 nm, and the removal rate is about 0.01 μm / h.

[0086] Based on the data from Example 1 and Comparative Examples 1 and 2, it can be seen that the combined effect of low pressure and ultraviolet light can significantly increase polishing efficiency. Without ultraviolet light, diamond is polished only in a low-pressure oxygen atmosphere, resulting in low oxidation efficiency. Without low pressure, the polishing rate further decreases because 172nm ultraviolet light attenuates rapidly in the atmosphere and cannot effectively act on the diamond surface.

[0087] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0088] Furthermore, throughout this specification, references to "an embodiment"; "an embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. Therefore, the appearance of the phrase "in one embodiment;" throughout this specification, and similar language, may, but not necessarily, refer to the same embodiment.

[0089] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A device for promoting high efficiency polishing of diamond by ultraviolet irradiation at low pressure, characterized by, The device includes a sealed chamber (2) and an upper rotating shaft (8), a lower rotating shaft (4), a polishing plate (3), and an ultraviolet lamp (5) disposed inside the sealed chamber (2). The sealed chamber (2) contains a process gas and maintains a gas pressure of 0.2 torr to 2 torr. The process gas is one or more of O2, CH4, Cl2, CF4, and SF6. The lower part of the upper rotating shaft (8) is used to connect with the diamond to be polished (6) to drive the diamond to be polished (6) to rotate. The upper part of the lower rotating shaft (4) is connected with the polishing plate (3) to drive the polishing plate. (3) Rotation; The polishing plate (3) is made of transparent material or metal material with multiple light-transmitting holes, and is in contact with the diamond (6) to be polished to achieve friction polishing; The ultraviolet lamp (5) is set below the polishing plate (3) and is coaxially set with the upper rotating shaft (8) to emit ultraviolet light and make it pass through the polishing plate (3) to irradiate the polishing surface of the diamond (6) to be polished, thereby promoting the formation of a soft graphite layer on the polishing surface of the diamond (6) to be polished so as to facilitate polishing, and then the soft graphite layer is removed by friction using the polishing plate (3) at room temperature. The wavelength of the ultraviolet light emitted by the ultraviolet lamp (5) is 172nm.

2. The apparatus of claim 1, wherein, The sealed chamber (2) is provided with an air inlet (1) and an air outlet (7). The air inlet (1) is used to connect to the process gas pipeline to introduce process gas. The air outlet (7) is connected to the vacuum pump through the exhaust valve to adjust the exhaust rate of the sealed chamber (2), so as to cooperate with the air inlet rate to keep the air pressure of the sealed chamber (2) at 0.2 torr to 2 torr.

3. The apparatus of claim 1, wherein, A pressure sensor is provided on the upper rotating shaft (8) to measure the pressure applied to the diamond (6) to be ground.

4. The apparatus according to any one of claims 1 to 3, characterized in that, The polishing plate (3) is made of fused silica, synthetic silica, sapphire, iron-nickel transition metal or alumina ceramic.

5. A method for diamond polishing using the apparatus described in any one of claims 1 to 4, characterized in that, The method is specifically as follows: S1 fixes the diamond to be ground (6) at the lower end of the upper rotating shaft (8); S2 evacuates the sealed chamber (2) and then introduces process gas to maintain the gas pressure in the sealed chamber (2) at 0.2 torr to 2 torr. The process gas is one or more of O2, CH4, Cl2, CF4 and SF6. S3 turns on the ultraviolet lamp (5) so that the ultraviolet light passes through the polishing plate (3) and shines on the diamond to be polished (6), so that a soft graphite layer is generated on the polishing surface of the diamond to be polished (6), and the wavelength of the ultraviolet light is 172nm. S4 uses the lower rotating shaft (4) to drive the polishing plate (3) to rotate, and at the same time uses the upper rotating shaft (8) to drive the diamond to be polished (6) to rotate. By controlling the upper rotating shaft (8) to move up and down, the pressure applied to the diamond to be polished (6) is adjusted, thereby removing the soft graphite layer of the polished surface by friction at room temperature, thus achieving diamond polishing.

6. The method as described in claim 5, characterized in that, In step S2, the flow rate of the process gas is 100 sccm to 1000 sccm.

7. The method as described in claim 5 or 6, characterized in that, In step S4, the rotational speed of the lower rotating shaft (4) is 100 rpm to 500 rpm, the rotational speed of the upper rotating shaft (8) is 10 rpm to 50 rpm, and the pressure applied to the diamond to be ground (6) is 1 N to 20 N.

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