Diamond polishing method and device based on multi-wavelength composite irradiation

Abstract

The invention provides a diamond polishing method and device based on multi-wavelength composite irradiation. The diamond polishing method comprises the steps that a diamond piece is polished through the mechanical shearing effect between the diamond piece and a cast iron disc; in the polishing process, the diamond polishing working area is irradiated by ultraviolet light and infrared light; c-C bonds of carbon atoms on the surface of the diamond sheet are broken and recombined through irradiation of the ultraviolet light, meanwhile, iron oxide of the cast iron disc is excited through irradiation of the ultraviolet light to generate electron hole pairs, the surface of the diamond sheet is oxidized, and polishing of the diamond is achieved; through irradiation of infrared light, the surface of the diamond sheet is locally heated, the chemical removal rate is increased, the surface of the diamond sheet is softened, meanwhile, lattice vibration of the diamond sheet can be enhanced, and carbon atom C-C bonds on the surface of the diamond sheet are promoted to be broken and recombined; the wavelength of the ultraviolet light ranges from 300 nm to 500 nm; and the wavelength of the infrared light is 915 nm. The device has the advantages of being controllable in area range, high in machining efficiency, low in cost and good in polishing quality.

Description

Technical Field

[0001] The invention relates to the technical field of diamond ultra-precision polishing, and in particular to a diamond polishing method and a device based on multi-wavelength composite irradiation. Background Art

[0002] Diamond has excellent semiconductor properties. Since the birth of artificial diamond, it has been hailed as the "ultimate semiconductor" material by the industry. It has an ultra-wide bandgap (5.45eV), high electron mobility (4500 cm 2 ·V -1 ·s -1 ), high electron saturation velocity (2.7×10 7 cm·s -1 ), high breakdown field strength (10 7 V cm -1 )、High thermal conductivity (2000W·m -1 ·K -1 ) and low dielectric constant (5.5). However, in order to fully utilize the semiconductor properties of diamond, certain requirements are often placed on its surface quality. When diamond film is used as a window material for different bands, in order to meet the needs of imaging or energy transmission, its two surfaces are required to be very smooth and low in damage, and the defects on the surface of the diamond film are minimized to avoid imaging distortion and component breakdown caused by the rough surface; when used as a microwave power device, if the surface quality is too poor, the excellent properties of the material itself, such as high frequency, high power and high temperature resistance, will be difficult to reflect, and may even lead to inaccurate information such as the predicted distance from the target to the electromagnetic wave emission point, radial velocity, and azimuth. Unfortunately, due to the extremely stable physical and chemical properties of diamond, how to ultra-precision process it to obtain diamond with high surface quality and meet industrial requirements has always been a key and urgent technical problem in the application of diamond semiconductors.

[0003] So far, researchers have developed many polishing technologies to reduce the surface roughness of single crystal diamond, including: Mechanical Polishing (MP), Chemical Mechanical Polishing (CMP), Thermochemical Polishing (TCP), Dynamic Friction Polishing (DFP), Laser Polishing (LP), Ion Beam Polishing (IBP), Hydroxyl Radicals Enhanced Chemical Polishing, etc. These methods have different removal mechanisms, which show differences in the final diamond surface quality and polishing efficiency. However, a careful analysis will reveal that they all have one common feature: creating an extreme environment (high temperature, high pressure, strong oxidation, etc.) to achieve phase change or qualitative change of diamond, thereby achieving its efficient removal. For example, the earliest MP method uses ultra-high rotation speed to rapidly increase the temperature of the processing area, while the DFP method generates considerable heat by applying a high mechanical load on the rotating polishing disk, thereby activating the thermochemical reaction of diamond to achieve phase change of diamond, thereby achieving effective removal of diamond surface material. However, the above methods usually have high requirements for equipment and environment, and have problems such as high energy consumption, poor safety and environmental protection.

[0004] Ultraviolet light irradiation-assisted diamond ultra-precision polishing is a new type of non-contact polishing technology developed in recent years. It uses the high energy characteristics of ultraviolet light to induce photochemical reactions or photophysical effects on the diamond surface, thereby achieving ultra-precision removal of materials. This technology combines the advantages of traditional mechanical polishing and photochemical treatment, and can achieve extremely high surface accuracy and finish at the nanometer or even sub-nanometer scale. It is particularly suitable for the processing of hard and brittle materials (such as diamond, silicon carbide, etc.). However, because it achieves higher surface accuracy, it means that it usually requires longer ultraviolet light irradiation time, thereby extending the processing cycle. Especially when facing large-sized workpieces or large-scale processing, its processing efficiency is low. At this stage, it is only suitable for specific fields with high added value and high precision requirements (such as optical components, semiconductor devices, etc.). Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a diamond polishing method and device based on multi-wavelength composite irradiation.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: In one aspect, the present invention provides a diamond polishing method based on multi-wavelength composite irradiation, comprising: The diamond sheet is polished by utilizing the mechanical shearing action between the diamond sheet and the cast iron disc; During the polishing process, ultraviolet light and infrared light are irradiated to the diamond polishing working area; the ultraviolet light irradiation causes the carbon atom CC bond on the surface of the diamond sheet to break and recombine, and at the same time, the ultraviolet light irradiation excites the iron oxide of the cast iron disk to produce electron-hole pairs, and oxidizes the surface of the diamond sheet, promotes chemical removal, and realizes the polishing of the diamond; the infrared light irradiation causes the surface of the diamond sheet to heat up locally, accelerates the chemical removal rate, and softens the surface of the diamond sheet. At the same time, the infrared light irradiation can enhance the lattice vibration of the diamond sheet and promote the breakage and recombination of the carbon atom CC bond on the surface of the diamond sheet; The wavelength of the ultraviolet light is 300nm-500nm; the wavelength of the infrared light is 915nm.

[0007] Furthermore, during the polishing process, the temperature of the polishing working area is maintained at 200°C-400°C.

[0008] On the other hand, the present invention also provides a diamond polishing device based on multi-wavelength composite irradiation, which is used to implement the above method, including an ultraviolet light source, an infrared light source, a multi-wavelength composite optical fiber, a load, a cast iron disk, a sample spinning device, and a main driving motor; The sample spinning device is used to fix and spin the diamond; The load is placed on the sample spinning device, the load and the sample spinning device are hollow in the middle, and the multi-wavelength composite optical fiber passes through the hollow cores of the load and the sample spinning device in sequence; one end of the multi-wavelength composite optical fiber is connected to the ultraviolet light source and the infrared light source, and the other end is placed above the diamond to irradiate the ultraviolet light and the infrared light on the surface of the diamond; A cast iron disk for rubbing diamond is arranged below the sample spinning device, and a main driving motor is arranged below the cast iron disk.

[0009] Furthermore, the sample spinning device includes a sample driving motor, a quartz glass sheet, and a metal clamp. A slot is provided at the center of the metal clamp. The sample driving motor is connected to the metal clamp. The quartz glass sheet is fixed inside the metal clamp, one side of which is connected to the sample driving motor and the other side is connected to the diamond.

[0010] Furthermore, the size of the card slot of the metal clamp is 5mm×5mm×0.3mm.

[0011] Furthermore, it also includes an oxygen enrichment device for providing a local oxygen-rich environment at the diamond.

[0012] Furthermore, the ultraviolet light source outputs ultraviolet light with a wavelength of 300nm-500nm and an output power of 250W-350W.

[0013] Furthermore, the infrared light source outputs infrared light with a wavelength of 915nm and an output power of 0W-300W.

[0014] Further, the rotation speed of the cast iron disc is 150 rpm.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are: The diamond polishing method and device based on multi-wavelength composite irradiation provided by the present invention realizes efficient and high-precision polishing of the diamond sheet by irradiating ultraviolet light and infrared light in the diamond polishing working area during the mechanical polishing of the diamond sheet and the cast iron disk.

[0016] Under the irradiation of ultraviolet light, the carbon atoms on the surface of the diamond sheet absorb the photon energy, which directly leads to the breakage and recombination of the CC bond. At the same time, due to the ultraviolet light irradiating the cast iron disk, the iron oxide in the cast iron disk is excited, causing the electrons to jump from the valence band to the conduction band, generating electron-hole pairs (electron e - and hole h + ), and combine with oxygen and water molecules in the air to form bonds, producing a large number of superoxide radicals (-O2) and hydroxyl radicals (-OH). The two free radicals produced oxidize the carbon atoms on the surface of the diamond sheet to form CO or CO2 for discharge; on the other hand, the hydroxyl radicals are adsorbed by iron oxides to form unstable intermediates, such as iron carbides or hydroxyl compounds. These active products further react with the surface of the diamond sheet to promote chemical removal of materials and achieve efficient and high-quality polishing of diamonds.

[0017] Under the irradiation of infrared light, on the one hand, the surface of the diamond sheet absorbs infrared light, resulting in local surface temperature rise, which accelerates the rate of photochemical reaction triggered by ultraviolet light, softens the surface of the diamond sheet, and enhances the effect of mechanical shearing removal of surface material; on the other hand, the photon energy of infrared light is low, which can interact with the vibration mode of the diamond sheet lattice, enhance the lattice vibration, promote the breakage and recombination of CC bonds caused by ultraviolet light, and relieve the residual stress on the surface of the diamond sheet during polishing, thereby reducing the microcracks or defects caused by polishing.

[0018] The diamond polishing method and device based on multi-wavelength composite irradiation provided by the present invention have the advantages of controllable regional range, high processing efficiency, low cost and good polishing quality, and can solve the problem that it is difficult to balance processing efficiency and quality with current technology. At the same time, the present invention is energy-saving and intensive and efficient, and meets the needs of large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of a diamond polishing device based on multi-wavelength composite irradiation provided by an embodiment; Figure 2 A schematic diagram of a sample spinning device provided by an embodiment; Figure 3 A schematic diagram of the mechanism of a diamond polishing method based on multi-wavelength composite irradiation provided by an embodiment.

[0021] Figure annotation: 1. Multi-wavelength composite optical fiber; 2. Load; 3. Diamond sheet; 4. Cast iron disk; 5. Sample spinning device; 6. Main drive motor; 7. Sample drive motor; 8. Quartz glass sheet; 9. Metal fixture. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] One embodiment provides a diamond polishing method based on multi-wavelength composite irradiation, comprising: The diamond sheet is polished by utilizing the mechanical shearing action between the diamond sheet 3 and the cast iron disc 4; During the polishing process, ultraviolet light and infrared light are irradiated to the diamond polishing working area; the ultraviolet light irradiation causes the carbon atom CC bond on the surface of the diamond sheet to break and recombine, and at the same time, the ultraviolet light irradiation excites the iron oxide of the cast iron disk to produce electron-hole pairs, and oxidizes the surface of the diamond sheet, promotes chemical removal, and realizes the polishing of the diamond; the infrared light irradiation causes the surface of the diamond sheet 3 to locally heat up, accelerates the chemical removal rate, and softens the surface of the diamond sheet 3. At the same time, the infrared light irradiation can enhance the lattice vibration of the diamond sheet 3, and promote the breakage and recombination of the carbon atom CC bond on the surface of the diamond sheet 3; The wavelength of the ultraviolet light is 300nm-500nm; the wavelength of the infrared light is 915nm.

[0024] Reference Figure 3Under the irradiation of ultraviolet light, the carbon atoms on the surface of the diamond sheet 3 absorb the photon energy, which directly leads to the breakage and recombination of the CC bond. At the same time, due to the ultraviolet light irradiating the cast iron disk 4, the iron oxide in the cast iron disk 4 is excited, causing the electrons to jump from the valence band to the conduction band, generating electron-hole pairs (electrons e - and hole h + ), and combine with oxygen and water molecules in the air to form a bond reaction, generating a large number of superoxide radicals (-O2) and hydroxyl radicals (-OH). The two free radicals generated oxidize the carbon atoms on the surface of the diamond sheet 3 to form CO or CO2 for discharge; on the other hand, the hydroxyl radicals are adsorbed by the iron oxide to form unstable intermediate products, such as iron carbides or hydroxyl compounds. These active products further react with the surface of the diamond sheet 3 to promote chemical removal of materials and achieve efficient and high-quality polishing of diamonds.

[0025] In one embodiment, during the polishing process, the temperature of the polishing working area is maintained at 200° C.-400° C. During the polishing process, infrared light is irradiated on the surface of the cast iron disk 4 and the diamond sheet 3. By adjusting the power and irradiation time of the infrared light, the temperature condition can be locally changed, and the time required for the diamond carbon to be transformed into a non-diamond phase can be reduced, thereby improving the diamond polishing efficiency; by adjusting and controlling the power and irradiation time of the infrared light, and irradiating only the diamond polishing working area, efficient energy utilization can be achieved.

[0026] Specifically, by keeping the temperature of the polishing working area at 200°C-400°C, polishing can be carried out smoothly and efficiently within this temperature range. This is because at high temperatures of 200°C-400°C, the diamond sheet 3 is more likely to react with oxygen (O2) or hydroxyl radicals (-OH) to generate CO or CO2 for volatilization and discharge; at the same time, within this temperature range, the process of diamond graphitization caused by ultraviolet light can be accelerated, thereby improving the polishing efficiency. When the temperature exceeds 400°C, excessive reaction may cause surface damage to the diamond sheet 3, affecting the final polishing quality; moreover, excessive temperature may also cause excessive graphitization and thermal stress causing microstructural damage.

[0027] In a preferred embodiment, the temperature of the polishing working area during the polishing process is maintained at 300° C. At this temperature, the surface oxidation rate of the diamond sheet 3 is significantly increased, and the degree of graphitization is within a controllable range.

[0028] Reference Figure 1 , one embodiment provides a diamond polishing device based on multi-wavelength composite irradiation, which is used to implement the above-mentioned diamond polishing method, including an ultraviolet light source, an infrared light source, a multi-wavelength composite optical fiber 1, a load 2, a cast iron disk 4, a sample spinning device 5, and a main driving motor 6; The sample spinning device 5 is used to fix and rotate the diamond; The load 2 is placed on the sample spinning device 5, the load 2 and the sample spinning device 5 are hollow in the middle, and the multi-wavelength composite optical fiber 1 passes through the load 2 and the hollow core of the sample spinning device 5 in sequence; one end of the multi-wavelength composite optical fiber 1 is connected to the ultraviolet light source and the infrared light source, and the other end is placed above the diamond to irradiate the ultraviolet light and the infrared light on the surface of the diamond; A cast iron disk 4 for rubbing diamond is arranged below the sample spinning device 5, and a main driving motor 6 is arranged below the cast iron disk.

[0029] The multi-wavelength composite optical fiber 1 allows both infrared and ultraviolet light to pass through.

[0030] In one embodiment, the ultraviolet light source outputs ultraviolet light with a wavelength of 300nm-500nm and an output power of 250W-350W, and the infrared light source outputs infrared light with a wavelength of 915nm and an output power of 0W-300W. Within this wavelength and output power range, it is beneficial to improve the polishing quality and polishing efficiency.

[0031] Reference Figure 2 In one embodiment, the sample spin device 5 includes a sample drive motor 7, a quartz glass sheet 8, and a metal clamp 9. A slot is provided at the center of the metal clamp 9. The sample drive motor 7 is connected to the metal clamp 9. The quartz glass sheet 8 is fixed inside the metal clamp, one side of which is connected to the sample drive motor 7, and the other side of which is connected to the diamond sheet 3. The diamond sheet is fixed by the metal clamp 9 so that it will not move laterally; ultraviolet light and infrared light are irradiated on the surface of the diamond sheet 3 through the multi-wavelength composite optical fiber 1 and the quartz glass sheet 8; through such a setting, the diamond sheet 3 is fixed while the area to be processed is exposed, which is conducive to the smooth progress of the polishing process.

[0032] The size of the clamping slot of the metal fixture is determined according to the size of the diamond.

[0033] Example: In one embodiment, the diamond sheet 3 is a single crystal diamond sheet (100 crystal orientation) with a size of 5 mm×5 mm×1 mm. The single crystal diamond sheet is a single crystal diamond sheet that has undergone primary grinding treatment before leaving the factory, and the initial surface roughness Ra is 2.51 nm (test area 0.14 mm×0.16 mm). After purchase, it is further ground, and the surface roughness Ra after grinding is 0.80 nm. Taking this surface roughness as the surface roughness before polishing, the single crystal diamond sheet is processed using the diamond polishing method and device based on multi-wavelength composite irradiation of the present invention.

[0034] In this embodiment, the size of the slot of the metal clamp 9 is 5 mm×5 mm×0.3 mm.

[0035] During the polishing process, the sample drive motor 7 and the main drive motor 6 drive the single crystal diamond sheet and the cast iron disk 4 to rotate in opposite directions respectively, and the rotation speed is kept consistent; the rotation speed of the cast iron disk 4 is 150rpm; the pressure of the load 2 is maintained at 0.4Mpa; the ultraviolet light source outputs ultraviolet light with a wavelength of 300nm-500nm, an output power of 278W, and an ultraviolet light intensity of 200mW / cm 2 The infrared light source outputs infrared light with a wavelength of 915nm, an output power of 300W, and an infrared light intensity of 200mW / cm 2 ; The polishing time is 8h, the ultraviolet light irradiation time is 8h, and the infrared light irradiation time is 1h.

[0036] Comparative Example: Meanwhile, the same settings as above were maintained, infrared light irradiation was removed, and the ultraviolet light irradiation time was controlled to 8 h and 10 h, and the single crystal diamond sheet was polished.

[0037] Under the above processing conditions, the surface roughness of the single crystal diamond sheet in the comparative example is reduced to 0.48nm (8h) and 0.37nm (10h), respectively; the surface roughness of the single crystal diamond sheet in the embodiment is reduced to 0.175nm, and the surface of the single crystal diamond sheet in the embodiment is uniform and smooth, without obvious scratches and defects, and the surface quality requirements of the composite diamond device with high precision and low damage are met. From the above comparison, it can be seen that compared with single ultraviolet irradiation assisted polishing, the polishing method provided by the present invention has faster polishing efficiency and better polishing quality.

[0038] Matters not covered by the present invention are known technologies.

[0039] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A diamond polishing method based on multi-wavelength composite irradiation, characterized in that: include: The diamond sheet is polished by utilizing the mechanical shearing action between the diamond sheet and the cast iron disc; During the polishing process, ultraviolet light and infrared light are irradiated to the diamond polishing working area; the ultraviolet light irradiation causes the carbon atom CC bond on the surface of the diamond sheet to break and recombine, and at the same time, the ultraviolet light irradiation excites the iron oxide of the cast iron disk to produce electron-hole pairs, and oxidizes the surface of the diamond sheet, promotes chemical removal, and realizes the polishing of the diamond; the infrared light irradiation causes the surface of the diamond sheet to heat up locally, accelerates the chemical removal rate, and softens the surface of the diamond sheet. At the same time, the infrared light irradiation can enhance the lattice vibration of the diamond sheet and promote the breakage and recombination of the carbon atom CC bond on the surface of the diamond sheet; The wavelength of the ultraviolet light is 300nm-500nm; the wavelength of the infrared light is 915nm.

2. The diamond polishing method based on multi-wavelength composite irradiation according to claim 1, characterized in that: During the polishing process, the temperature of the polishing working area is maintained at 200° C.-400° C.

3. A diamond polishing device based on multi-wavelength composite irradiation, used to implement the method as claimed in claim 1, characterized in that: It includes ultraviolet light source, infrared light source, multi-wavelength composite optical fiber, load, cast iron plate, sample spinning device, and main drive motor; The sample spinning device is used to fix and spin the diamond; The load is placed on the sample spinning device, the load and the sample spinning device are hollow in the middle, and the multi-wavelength composite optical fiber passes through the hollow cores of the load and the sample spinning device in sequence; one end of the multi-wavelength composite optical fiber is connected to the ultraviolet light source and the infrared light source, and the other end is placed above the diamond to irradiate the ultraviolet light and the infrared light on the surface of the diamond; A cast iron disk for rubbing diamond is arranged below the sample spinning device, and a main driving motor is arranged below the cast iron disk.

4. The diamond polishing device based on multi-wavelength composite irradiation as claimed in claim 3, characterized in that: The sample spinning device comprises a sample driving motor, a quartz glass sheet and a metal clamp. A slot is provided at the center of the metal clamp. The sample driving motor is connected to the metal clamp. The quartz glass sheet is fixed inside the metal clamp, with one side connected to the sample driving motor and the other side connected to the diamond.

5. The diamond polishing device based on multi-wavelength composite irradiation as claimed in claim 4, characterized in that: The size of the card slot of the metal clamp is 5mm×5mm×0.3mm.

6. The diamond polishing device based on multi-wavelength composite irradiation as claimed in claim 3, characterized in that: Also included is an oxygen enrichment device for providing a local oxygen-enriched environment at the diamond.

7. The diamond polishing device based on multi-wavelength composite irradiation as claimed in claim 3, characterized in that: The ultraviolet light source outputs ultraviolet light with a wavelength of 300nm-500nm and an output power of 250W-350W.

8. The diamond polishing device based on multi-wavelength composite irradiation as claimed in claim 3, characterized in that: The infrared light source outputs infrared light with a wavelength of 915nm and an output power of 0W-300W.

9. The diamond polishing device based on multi-wavelength composite irradiation as claimed in claim 3, characterized in that: The cast iron disc was rotated at 150 rpm.

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