Device and method for promoting efficient polishing of diamond through ultraviolet irradiation under low air pressure

Abstract

The invention belongs to the field of diamond polishing, and particularly discloses a device and method for promoting efficient diamond polishing through ultraviolet irradiation under the low air pressure, the device comprises a sealed cavity, an upper rotating shaft, a lower rotating shaft, a polishing plate and an ultraviolet lamp, the upper rotating shaft, the lower rotating shaft, the polishing plate and the ultraviolet lamp are arranged in the sealed cavity, process gas is contained in the sealed cavity, and the air pressure is kept at 0.2 torr to 2 torr; the lower part of the upper rotating shaft is connected with a to-be-ground diamond; the upper part of the lower rotating shaft is connected with a polishing plate; the polishing plate is made of a transparent material or a metal material with a plurality of light through holes, and is in contact with the diamond to be ground; and the ultraviolet lamp is arranged below the polishing plate and is coaxial with the upper rotating shaft. According to the method, the to-be-ground diamond is irradiated by the ultraviolet rays under the low air pressure, so that the diamond can be preferentially graphitized to form the soft graphite layer, and then the soft graphite layer is rubbed and removed by the polishing plate at the normal temperature, and the diamond can be effectively prevented from being damaged.

Description

Technical Field

[0001] The present application belongs to the field of diamond polishing, and more specifically, to a device and method for promoting efficient diamond polishing by ultraviolet irradiation under low pressure. Background Art

[0002] Diamond has excellent mechanical, electrical, thermal, and optical properties, and has broad application prospects in high-tech fields such as machinery, microelectronics, biomedicine, aerospace, and nuclear energy. However, almost all application fields have strict requirements on the surface quality of diamond, requiring low surface damage and nanometer-level surface roughness. The surface quality of diamond will greatly affect the performance and stability of the device, and is an important factor in measuring the quality of diamond devices. However, the high brittleness of diamond, the highest hardness in nature, and extremely strong chemical stability make its surface processing difficult and inefficient. Therefore, it is crucial to develop a method that can polish diamond efficiently and with high quality.

[0003] The basic methods of diamond material removal include: micro-crushing caused by physical and mechanical methods; removal of diamond surface atoms by bonding viscosity; destruction of the original carbon chain structure of diamond to transform it into amorphous carbon such as graphite, and then removal by mechanical methods. Based on these material removal methods, at present, diamond polishing mainly includes mechanical polishing, thermochemical polishing, dynamic friction polishing, chemical mechanical polishing, laser polishing, ion beam polishing, etc. Although a variety of diamond polishing methods have been proposed, the industrialized high-efficiency and high-quality polishing technology is not perfect. In some high-precision occasions, it is required to quickly achieve an atomic-level flat surface while minimizing and avoiding surface and subsurface damage, and traditional polishing methods still have many problems.

[0004] The disadvantage of mechanical polishing is that it is easy to cause the diamond surface to break and damage after strong mechanical scratching; thermochemical polishing needs to be processed in a high temperature and closed environment, which is easy to cause 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 break; the surface quality of chemical mechanical polishing is relatively high, but its disadvantages are low processing efficiency, and the corrosive waste liquid is difficult to handle and pollutes the environment; the roughness and surface accuracy after laser polishing are low, and cracks are easily generated on the surface, which is suitable for rough processing; ion beam polishing has high processing accuracy, but low removal rate, small ion beam area, not suitable for polishing large-area diamond processing, and the polishing process requires a high vacuum environment, and the equipment cost is relatively high. UV-assisted polishing technology and plasma-assisted polishing use ultraviolet rays or plasma to induce the generation of hydroxyl radicals, and use the reaction between hydroxyl radicals and the diamond surface to remove materials. CN117681064A discloses a diamond rapid polishing method and device based on ultraviolet light, which combines mechanical polishing and chemical oxidation polishing in an atmospheric environment, uses oxygen supplied by an ultraviolet unit and an oxygen supply unit to generate oxygen free radicals and ozone, and modifies the diamond surface in combination with a polishing liquid, thereby increasing the polishing speed. CN118456249A discloses a diamond substrate ultraviolet light-vibration assisted polishing method and equipment, which performs ultrasonic vibration assisted polishing on diamonds under ultraviolet light irradiation, and the diamond material is mainly removed by the stress and high temperature generated by the vibration excitation of the surface to be processed, and the ultraviolet light source is placed outside the vacuum chamber. The ultraviolet light source is placed outside the vacuum chamber and is blocked by the atmosphere, and its role in polishing is very limited. This technology combines multiple energy fields, but has the problems of complex process and difficult control, and can cause damage or even breakage of diamonds due to high temperature and stress. Summary of the invention

[0005] In view of the defects of the prior art, the present application provides a device and method for promoting efficient polishing of diamond by ultraviolet irradiation under low pressure, aiming to solve the problem that the existing ultraviolet-assisted polishing technology needs to be combined with other auxiliary means.

[0006] According to one aspect of the present application, a device for promoting efficient polishing of diamond by ultraviolet irradiation under low pressure is provided, which specifically comprises a sealed chamber and an upper rotating shaft, a lower rotating shaft, a polishing plate and an ultraviolet lamp arranged inside the sealed chamber, wherein the sealed chamber has a process gas inside and the pressure is maintained at 0.2 torr to 2 torr; the lower part of the upper rotating shaft is used to connect with the diamond to be polished to drive the diamond to be polished to rotate; the upper part of the lower rotating shaft is connected with the polishing plate to drive the polishing plate to rotate; the polishing plate is made of a transparent material or a metal material with a plurality of light-through holes, and contacts with the diamond to be polished to achieve friction polishing; the ultraviolet lamp is arranged below the polishing plate and coaxially with the upper rotating shaft, and is used to emit ultraviolet rays and make them pass through the polishing plate to irradiate the polishing surface of the diamond to be polished, thereby promoting the production of a soft graphite layer on the polishing surface of the diamond to be polished for easy polishing.

[0007] Compared with the prior art, the above technical solution conceived by the present application can effectively improve the polishing efficiency and avoid damage to the diamond without combining other auxiliary means because the present application proposes to use ultraviolet rays to irradiate diamond under low pressure.

[0008] As further preferred, the process gas is O 2 , CH 4 , Cl 2 CF 4 and SF 6 One or more of .

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

[0010] As a further preference, the sealed chamber is provided with an air inlet and an exhaust port, the air inlet is used to be connected to a process gas pipeline to introduce process gas, and the exhaust port is connected to a vacuum pump via an exhaust valve to adjust the exhaust rate of the sealed chamber, thereby cooperating with the air inlet rate to keep the air pressure of the sealed chamber at 0.2 torr to 2 torr.

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

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

[0013] According to another aspect of the present application, a method for diamond polishing using the above-mentioned device is provided, and the method is specifically as follows:

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

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

[0016] S3 turns on the ultraviolet lamp to allow ultraviolet rays to pass through the polishing plate and irradiate the diamond to be ground, so that a soft graphite layer is generated on the polishing surface of the diamond to be ground;

[0017] S4 uses the lower rotating shaft to drive the polishing disc to rotate, and uses the upper rotating shaft to drive the diamond to be ground to rotate, and controls the upper rotating shaft to move up and down to adjust the pressure applied to the diamond to be ground, so as to remove the soft graphite layer on the polishing surface through friction, thereby achieving diamond polishing.

[0018] As a further preferred embodiment, in step S2, the process gas is O 2 , CH 4 , Cl 2 CF 4 and SF 6 One or more of the above, the flow rate of the process gas is 100 sccm to 1000 sccm.

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

[0020] As further preferred, in step S4, the rotation speed of the lower rotating shaft is 100 rpm to 500 rpm, the rotation 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 general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art:

[0022] 1. The present application utilizes ultraviolet rays to irradiate the diamond to be polished under low pressure, which can not only excite the diamond, but also generate O* and ozone with strong oxidizing properties to form a strong oxidizing atmosphere, so that the C atoms in the protruding part of the diamond polishing surface are more active and are preferentially graphitized to form a soft graphite layer, which is then removed by friction of the polishing plate at room temperature, and finally a sub-nanometer ultra-smooth surface is formed. In addition, no other auxiliary means are required, which not only simplifies the process and device structure, but also effectively avoids damage to the diamond.

[0023] 2. In particular, the present application optimizes the wavelength of ultraviolet light emitted by the ultraviolet lamp, which can be combined with low air pressure to avoid ultraviolet attenuation, and can stimulate diamond to produce holes and electron pairs, greatly promoting its chemical reaction, and combining with a strong oxidizing atmosphere to make it easier to transform into graphite;

[0024] 3. At the same time, the present application also optimizes the rotation speed of the lower rotating shaft, the rotation speed of the upper rotating shaft and the pressure applied to the diamond to be polished, which can achieve efficient and stable polishing in coordination with the air pressure and ultraviolet wavelength, thereby ensuring the polishing effect while avoiding the breakage of the diamond. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of a device for promoting efficient diamond polishing by ultraviolet irradiation under low pressure provided in an embodiment of the present application;

[0026] Figure 2 is the white light interference pattern of the polished diamond in Example 1 of the present application;

[0027] Figure 3 is the white light interference pattern of the polished diamond in Example 2 of the present application;

[0028] Figure 4 is the white light interference pattern of the polished diamond in Example 3 of the present application;

[0029] Figure 5 is the white light interference pattern of the polished diamond in Example 4 of the present application;

[0030] Figure 6 is the white light interference pattern of the polished diamond in Example 5 of the present application;

[0031] Figure 7 is the white light interference pattern of the polished diamond in Example 6 of the present application;

[0032] Figure 8 is the white light interference pattern of the polished diamond in Example 7 of the present application;

[0033] Fig. 9 is the white light interference pattern of the polished diamond in Comparative Example 1 of the present application;

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

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

[0036] Fig.12 is the surface Raman image of the diamond after polishing in Example 1 of the present application;

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

[0038] Throughout the 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 DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0041] like Figure 1 As shown, the present application provides a device for promoting efficient polishing of diamond by ultraviolet irradiation under low pressure, specifically comprising a sealed chamber 2 and an upper rotating shaft 8, a lower rotating shaft 4, a polishing plate 3 and an ultraviolet lamp 5 arranged inside the sealed chamber 2. The sealed chamber 2 has a process gas inside and the air pressure is maintained at 0.2torr to 2torr. When the air pressure is too high, the gas molecules have a greater blocking effect on ultraviolet rays, affecting the intensity of ultraviolet irradiation. At the same time, the oxygen free radicals generated by ultraviolet ionization under a higher oxygen concentration will combine with other molecules to reduce their concentration, thereby reducing the oxidizing property of the atmosphere. When the air pressure is too low, the oxygen concentration is too low, which will limit the generation of oxygen free radicals and reduce the oxidizing property of the gas atmosphere in the chamber. The sealed chamber 2 is provided with an air inlet 1 and an exhaust port 7. The air inlet 1 is used to be connected to a process gas pipeline to introduce process gas. The exhaust port 7 is connected to a vacuum pump through an exhaust valve to adjust the exhaust rate of the sealed chamber 2, thereby cooperating with the air inlet rate to keep the air pressure of the sealed chamber 2 at 0.2torr to 2torr.

[0042] The lower part of the upper rotating shaft 8 is used to connect with the diamond to be ground 6 to drive the diamond to be ground 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 to rotate. The contact surface between the diamond to be ground 6 and the polishing plate 3 is a grinding and polishing surface. The polishing plate 3 and the diamond to be ground 6 are in contact and rotate relative to each other, so that friction polishing of the grinding and 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 to be ground 6 and the polishing plate 3, and apply a certain pressure.

[0043] The polishing plate 3 is made of a transparent material or a metal material with a plurality of light holes. The ultraviolet lamp 5 is arranged below the polishing plate 3 and coaxially with the upper rotating shaft 8. The lamp tube of the ultraviolet lamp 5 faces upward, and is used to emit ultraviolet rays and pass through the polishing plate 3 to irradiate the polishing surface of the diamond 6 to be ground, thereby promoting the formation of a soft graphite layer on the polishing surface of the diamond 6 to be ground. The hardness of the soft graphite layer is relatively low, so it only needs low-pressure friction polishing to be removed, thereby achieving efficient and non-destructive polishing of the diamond.

[0044] Furthermore, the process gas is O 2 , CH 4 , Cl2 CF 4 and SF 6 The purity of one or more of the above is 99.99%. The air pressure of the sealed chamber 2 is 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] Further, the wavelength of the ultraviolet light emitted by the ultraviolet lamp 5 is 172nm. The present application adopts 172nm excimer ultraviolet light to promote the polishing plate to efficiently polish diamond. Under atmospheric conditions, 172nm excimer ultraviolet light will be absorbed by molecules in the atmosphere and decay rapidly, and the irradiation distance is within 3mm. Under low-pressure conditions, 172nm excimer ultraviolet light is not easy to decay, the irradiation intensity is stronger, and the irradiation distance is farther. The band gap energy of diamond is 5.5eV. Directly irradiating the contact surface of diamond polishing with 172nm (7.2eV) excimer ultraviolet light can excite diamond to produce holes and electron pairs, greatly promoting chemical reactions.

[0046] The power cord and heat dissipation device of the ultraviolet lamp 5 are arranged on the outside of the sealed chamber 2 and placed in the atmospheric environment, so as to simplify the device structure of the sealed chamber 2. The light source line and water-cooling tube of the ultraviolet lamp 5 realize the conversion from atmosphere 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 tube.

[0047] Furthermore, a pressure sensor is provided on the upper rotating shaft 8 for measuring 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 quartz, synthetic quartz, sapphire, iron-nickel transition metal or alumina ceramic.

[0049] According to another aspect of the present application, a method for diamond polishing using the above-mentioned device is provided, and the method is specifically as follows:

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

[0051] S2: Close the door of the sealed chamber 2, turn on the vacuum pump to evacuate the air from the exhaust port 7, and then introduce the process gas from the air inlet 1, and coordinate the exhaust valve and the vacuum pump to maintain the air pressure of the sealed chamber 2 at 0.2 torr to 2 torr;

[0052] S3: turning on the ultraviolet lamp 5 to allow ultraviolet rays to pass through the polishing plate 3 and irradiate the diamond 6 to be ground, so that a soft graphite layer is generated on the polishing surface of the diamond 6 to be ground;

[0053] S4 utilizes the lower rotating shaft 4 to drive the polishing disc 3 to rotate, and utilizes the upper rotating shaft 8 to drive the diamond 6 to be ground to rotate, and controls the upper rotating shaft 8 to move up and down to adjust the pressure applied to the diamond 6 to be ground, so as to remove the soft graphite layer on the grinding and polishing surface by friction, so as to achieve diamond polishing;

[0054] S5 After polishing is completed, the upper rotating shaft 8 is moved to separate the diamond 6 to be polished from the polishing plate 3, the upper rotating shaft 8 and the lower rotating shaft 4 are stopped from rotating, the introduction of process gas is stopped, the ultraviolet lamp 5 is turned off, and the chamber door of the sealed chamber 2 is opened to take out the polished diamond.

[0055] Further, in step S2, the process gas is a gas that can process diamond, preferably O 2 , CH 4 , Cl 2 CF 4 and SF 6 One or more of the process gases, the flow rate of which is 100 sccm to 1000 sccm. As the only material input into the closed chamber 2 during the polishing process, no abrasive particles and polishing liquid are required, thus avoiding pollution of the polishing environment and achieving the purpose of dry non-polluting polishing.

[0056] Preferably, the air pressure of 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 ultraviolet light is 172nm, and the application uses 172nm excimer ultraviolet light to promote the efficient polishing of diamonds by polishing plates. In atmospheric environment, 172nm excimer ultraviolet light will be absorbed by molecules in the atmosphere and decay rapidly, and the irradiation distance is within 3mm. In low-pressure environment, 172nm excimer ultraviolet light is not easy to decay, the irradiation intensity is stronger, and the irradiation distance is farther. The band gap energy of diamond is 5.5eV. Directly irradiating the contact surface of diamond polishing with 172nm (7.2eV) excimer ultraviolet light can excite diamond to produce holes and electron pairs, greatly promoting chemical reactions.

[0058] Further, in step S4, the rotation speed of the lower rotating shaft 4 is 100rpm~500rpm, preferably 300rpm~500rpm, the rotation speed of the upper rotating shaft 8 is 10rpm~50rpm, and the pressure applied to the diamond 6 to be polished is 1N~20N, preferably 10N~15N. The lower rotation speed and load improve the stability of the polishing process, greatly reduce the possibility of sample breakage during the polishing process, and quickly obtain an atomic-scale ultra-smooth surface while ensuring a high yield and no damage to the sample. When the air pressure is reduced, the gas atmosphere reduces the blocking of ultraviolet rays, the ultraviolet radiation is enhanced, and the hydrophilicity of the polishing disc and the diamond is improved, thereby enhancing mechanical friction and bonding; when the rotation speed is increased, the mechanical friction between the diamond and the polishing disc is enhanced, but when the rotation speed is too high, the local temperature reaches the diamond graphitization temperature, and the random graphitization of the diamond will cause the surface and sub-surface quality to decrease; when the pressure is increased, the mechanical friction between the diamond and the polishing disc is enhanced, but when the pressure is too high, the mechanical stress on the diamond is large, which is easy to cause mechanical damage or even breakage of the diamond. Therefore, the rotation speed, pressure and air pressure jointly affect the friction and bonding between the diamond and the polishing disk. It is necessary to promote mechanical friction and bonding to improve the polishing rate and surface roughness while ensuring the surface quality of the diamond.

[0059] Compared with the prior art, the present application does not require high rotation speed and high load, can achieve high removal rate under normal temperature and low pressure environment, 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 closed chamber 2 can ionize to produce oxygen free radicals and react to produce ozone under the irradiation of excimer ultraviolet rays, forming a strong oxidizing atmosphere. Combined with the low-pressure environment, diamond is more likely to transform into graphite. Therefore, the high material removal rate of diamond is the combined effect of graphitization and bonding removal. Graphite has a very low hardness relative to the diamond phase and is simple to remove. Therefore, the high material removal rate is mainly determined by the diamond graphitization rate, thereby obtaining a relatively high removal rate. In the preferred embodiment of the present application, the diamond polishing removal rate was measured. Compared with the conventional diamond polishing method, the polishing rate of the low-pressure ultraviolet assisted polishing technology proposed in the present application can reach more than 0.94 microns per hour, which is more 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 on the protruding parts of the diamond surface are more active and are graphitized first. They are removed by friction of the soft polishing pad at room temperature, eventually forming a sub-nanometer ultra-smooth surface.

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

[0063] 3. Low damage to diamond surface: The low speed and low load during the polishing process make the polishing process more stable and the diamond is not easy to break. The hardness of the polishing plates such as quartz glass (10.84Gpa) and iron-nickel transition metal (<5Gpa) used in polishing is much lower than that of diamond (80-120Gpa), which will not cause surface damage to the diamond and non-diamond phase residue after polishing. Fig.13 As shown in Figure 1, Raman testing after diamond polishing shows that the surface is pure diamond phase. A temperature sensor is used to measure the temperature of the diamond sample in real time. The results are shown in Figure 1. Fig.13 As shown, the diamond temperature is below 150°C, which is much lower than the high-temperature graphitization temperature of diamond, proving UV-induced graphitization. It can also prevent defects such as graphite nucleation inside the diamond caused by high-temperature graphitization, effectively improving sample quality and preventing diamond damage and breakage.

[0064] 4. No environmental pollution and waste: During the polishing process, the material input into the closed chamber is only dry gas with a purity of 99.99%, that is, the polishing is completely carried out in dry gas, and no polishing liquid composed of abrasives and chemical reagents is required, which can avoid polluting the diamond and the processing environment, and no waste liquid is generated.

[0065] The technical solution provided in this application is further described below based on specific embodiments and comparative examples 1 and 2.

[0066] Example 1

[0067] First, fix the polishing plate 3 on the lower rotating shaft 4, fix the diamond 6 to be ground on the lower end of the upper rotating shaft 8, then close the door of the closed chamber 2, turn on the vacuum pump, evacuate to low pressure, and then introduce 200sccm of oxygen into the closed chamber 2 from the air inlet 1, adjust the vacuum valve to control it in a low-pressure environment of 1torr, and 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 with the diamond 6, and the lamp tube faces upward. The ultraviolet light 5 is directly irradiated through the polishing plate 3 to the surface of the diamond 6 in contact with the polishing plate 3, thereby exciting the diamond 6 and generating O* and ozone with strong oxidizing properties to form a strong oxidizing atmosphere. The polishing plate 3 rotates driven by the lower rotating shaft 4, and the upper rotating shaft 8 holding the diamond substrate 6 starts to rotate. The 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 300ppm, the rotation speed of the lower rotating shaft 4 is 20rpm, and the pressure applied to the diamond 6 to be ground is 10N. The soft graphite layer on the polishing surface is removed by friction. After the processing is completed, 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 taken out. Under the promotion of this method, the atomic-scale damage-free diamond surface is finally obtained by high removal polishing. After polishing for 1 hour, the surface roughness is as follows Figure 2 As shown, the surface roughness Sa of the diamond sample dropped below 0.3 nm and the removal rate was 5.8 μm / h.

[0068] Example 2

[0069] Same as in Example 1, except that 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, and the pressure applied to the diamond 6 to be polished is 10 N. After polishing for 1 hour, the surface roughness is as follows: Figure 3 As shown, the surface roughness Sa of the diamond sample dropped below 0.3 nm and the removal rate was 8.0 μm / h.

[0070] Example 3

[0071] Same as Example 1, except that the gas 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, and the pressure applied to the diamond 6 to be polished is 10 N. After polishing for 1 hour, the surface roughness 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] The same as in Example 1, except that the gas 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, and the pressure applied to the diamond 6 to be polished is 10 N. After polishing for 1 hour, the surface roughness 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 in Example 1, except that the gas pressure was 1 torr, the rotation speed of the upper rotating shaft 8 was 20 ppm, the rotation speed of the lower rotating shaft 4 was 500 rpm, and the pressure applied to the diamond 6 to be polished was 10 N. After polishing for 1 hour, the surface roughness was as follows: Figure 6 As 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 that the gas 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, and the pressure applied to the diamond 6 to be polished is 1 N. After polishing for 1 hour, the surface roughness 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 in Example 1, except that the gas pressure was 1 torr, the rotation speed of the upper rotating shaft 8 was 20 ppm, the rotation speed of the lower rotating shaft 4 was 300 rpm, and the pressure applied to the diamond 6 to be polished was 15 N. After polishing for 1 hour, the surface roughness was 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 that the gas pressure was 10 torr. After polishing for 1 hour, the surface roughness was as follows: Fig. 9 As shown, the removal rate is 0.01 μm / h, and the effect is close to that in the atmospheric environment.

[0082] Comparative Example 2

[0083] The same as in Example 1, except that the ultraviolet lamp was not used to irradiate the diamond 6 to be polished. After polishing for 1 hour, the surface roughness was as follows: Fig.10 As shown, after polishing for 1 hour, the surface roughness Sa is about 2nm, and the removal rate is about 0.08μm / h.

[0084] Comparative Example 3

[0085] Same as in Example 1, except that the low pressure environment does not exist and the sealed chamber 2 is in the atmospheric environment. Fig.11 As shown, after polishing for 1 hour, the surface roughness Sa is about 2nm, and the removal rate is about 0.01μm / h.

[0086] Combining the data of Example 1 and Comparative Examples 1 and 2, it can be seen that the combined effect of low pressure and ultraviolet light can greatly increase the polishing efficiency. In the absence of ultraviolet light, diamond is polished only in a low-pressure oxygen atmosphere, and the oxidation efficiency is low. In the absence of low pressure, the polishing rate is further reduced because the 172nm ultraviolet light will decay rapidly in the atmosphere and cannot effectively act on the diamond surface.

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

[0088] In addition, references throughout this specification to "one embodiment"; "one embodiment", "an example" or similar language indicate that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment"; "in one embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0089] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A device for promoting efficient diamond polishing by ultraviolet irradiation under low pressure, characterized in that: The device comprises a sealed chamber (2), an upper rotating shaft (8), a lower rotating shaft (4), a polishing plate (3) and an ultraviolet lamp (5) arranged inside the sealed chamber (2); the sealed chamber (2) has a process gas inside and the gas pressure is maintained at 0.2 torr to 2 torr; the lower part of the upper rotating shaft (8) is used to connect with the diamond to be ground (6) to drive the diamond to be ground (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) to rotate; the polishing plate (3) is made of a transparent material or a metal material with a plurality of light-through holes, and is in contact with the diamond to be ground (6) to achieve friction polishing; the ultraviolet lamp (5) is arranged below the polishing plate (3) and coaxially with the upper rotating shaft (8), and is used to emit ultraviolet rays and pass through the polishing plate (3) to irradiate the polishing surface of the diamond to be ground (6), thereby promoting the production of a soft graphite layer on the polishing surface of the diamond to be ground (6) for easy polishing.

2. The device according to claim 1, characterized in that The process gas is one or more of O2, CH4, Cl2, CF4 and SF6.

3. The device according to claim 1, characterized in that The wavelength of the ultraviolet light emitted by the ultraviolet lamp (5) is 172 nm.

4. The device according to claim 1, characterized in that The sealed chamber (2) is provided with an air inlet (1) and an exhaust port (7); the air inlet (1) is used to be connected to a process gas pipeline to allow the process gas to enter; the exhaust port (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 air inlet rate to keep the air pressure of the sealed chamber (2) at 0.2 torr to 2 torr.

5. The device according to claim 1, characterized in that The upper rotating shaft (8) is provided with a pressure sensor for measuring the pressure applied to the diamond (6) to be ground.

6. The device according to any one of claims 1 to 5, characterized in that: The polishing plate (3) is made of fused quartz, synthetic quartz, sapphire, iron-nickel transition metal or alumina ceramic.

7. A method for diamond polishing using the device according to any one of claims 1 to 6, characterized in that: The method is specifically as follows: S1 fixes the diamond to be ground (6) on the lower end of the upper rotating shaft (8); S2 evacuates the sealed chamber (2) and then introduces a process gas to maintain the air pressure of the sealed chamber (2) at 0.2 torr to 2 torr; S3: turning on the ultraviolet lamp (5) to allow ultraviolet rays to pass through the polishing plate (3) and irradiate the diamond to be ground (6), so that a soft graphite layer is generated on the polishing surface of the diamond to be ground (6); S4 utilizes the lower rotating shaft (4) to drive the polishing disc (3) to rotate, and utilizes the upper rotating shaft (8) to drive the diamond to be ground (6) to rotate, and controls the upper rotating shaft (8) to move up and down to adjust the pressure applied to the diamond to be ground (6), thereby removing the soft graphite layer on the polishing surface through friction, thereby achieving diamond polishing.

8. The method according to claim 7, characterized in that: 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.

9. The method according to claim 7, characterized in that: The wavelength of the ultraviolet rays is 172 nm.

10. The method according to any one of claims 7 to 9, characterized in that: In step S4, the rotation speed of the lower rotating shaft (4) is 100 rpm to 500 rpm, the rotation speed of the upper rotating shaft (8) is 10 rpm to 50 rpm, and the pressure applied to the diamond (6) to be ground is 1 N to 20 N.

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