An integrated diamond growth and polishing method based on cluster bundles and localized substrate bias.

Abstract

This invention relates to the field of diamond material preparation technology, specifically to an integrated diamond growth and polishing method based on cluster bundles and localized substrate bias. First, the diamond substrate is pretreated, and its three-dimensional surface morphology is obtained using atomic force microscopy to determine concave and convex regions. Based on this, a localized bias distribution pattern is designed. A larger negative bias is applied to the concave regions, and a smaller negative bias is applied to the convex regions, generating carbonaceous cluster bundles of 3-10 nanometers in size and guiding them to the substrate surface. Under the action of localized bias, high-energy clusters preferentially deposit in the concave regions, while low-energy clusters deposit in the convex regions, thus simultaneously achieving integrated diamond surface growth and polishing. This integration of growth and polishing simplifies the process, significantly reduces processing time and cost, and improves production efficiency.

Description

Technical Field

[0001] This invention relates to the field of diamond material preparation technology, specifically to an integrated diamond growth and polishing method based on cluster bundles and local substrate bias, and particularly to a technical solution that can simultaneously achieve diamond surface growth and polishing. Background Technology

[0002] Diamond, as a semiconductor material with a wide bandgap, possesses excellent electrical and thermal properties, including high electron and hole mobility, high breakdown strength, and high thermal conductivity. These characteristics make diamond a promising candidate for applications in high-power and high-frequency electronic devices. High-quality single-crystal diamond is fundamental to the application of diamond materials. However, the growth process of single-crystal diamond is constrained by various factors such as diamond quality, growth surface quality, and temperature, resulting in a low epitaxial production rate and making it difficult to produce high-quality diamond materials.

[0003] Currently, diamond materials are mainly prepared through epitaxial growth. For example, Chinese patent CN112899774 B discloses "a method for homoepitaxial growth of single-crystal diamond from natural diamond." This method includes selecting high-quality natural diamond as a substrate, subjecting its surface to immersion cleaning, planarization, acid treatment, ultrasonic cleaning, and etching, followed by epitaxial growth under specific conditions. The epitaxially grown surface is then beveled to form two large-area single-crystal diamond surfaces, which are then joined together for further epitaxial growth. This method, through multi-step pretreatment, can reduce impurities and defects on the surface of the natural diamond substrate, thereby improving the quality of epitaxial growth.

[0004] However, the above methods have the following drawbacks: First, growth and polishing are two independent processes, requiring multiple changes in the process environment, which increases the complexity of the process and the production cost; second, mechanical polishing can easily cause subsurface damage to the surface, affecting the crystal integrity of diamond; third, the chemical reagents used in chemical treatment methods are not environmentally friendly and have low safety; finally, the multi-step processing is time-consuming and inefficient.

[0005] Therefore, there is an urgent need to develop a new diamond growth and polishing technology that can integrate growth and polishing into a single process, thereby improving processing efficiency, reducing production costs, and ensuring the high quality of diamond materials. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides an integrated diamond growth and polishing method based on cluster bundles and local substrate bias. This method combines cluster bundle technology with local substrate bias to achieve an integrated process of diamond surface growth and polishing, which not only simplifies the processing flow and reduces production costs, but also improves diamond surface quality and growth efficiency.

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows: An integrated diamond growth and polishing method based on cluster bundles and local substrate bias includes the following steps: Select a diamond substrate and pretreat the surface of the diamond substrate; The surface of the diamond substrate was scanned using an atomic force microscope to obtain a three-dimensional surface topography image, and the surface depression and flat areas were identified. Based on the surface three-dimensional topography map, a local bias voltage distribution map is designed, and a larger negative bias voltage is distributed to the recessed area, while a smaller negative bias voltage is distributed to the flat area. Carbonaceous clusters are generated, wherein the size distribution of the carbonaceous clusters is 3-10 nanometers; A negative bias voltage corresponding to the local bias voltage distribution pattern is applied to the diamond substrate; The carbonaceous clusters are guided to the surface of the diamond substrate. Under the action of the local bias voltage, the higher-energy carbonaceous clusters are preferentially deposited in the recessed area, while the lower-energy carbonaceous clusters are deposited in the flat area, thereby achieving the integration of diamond surface growth and polishing.

[0008] Preferably, the method for preparing the carbonaceous cluster bundle is as follows: using a radio frequency plasma-assisted magnetron sputtering system, with graphite as the target material, sputtering is performed in a mixed atmosphere of argon and methane. The operating frequency of the radio frequency plasma-assisted magnetron sputtering system is 8.56 MHz, the power is 500-1500 watts, the volume ratio of argon to methane is 95:5, and the pressure of the sputtering chamber is controlled at 2-8 Pascals.

[0009] Preferably, the carbon cluster bundle includes carbon clusters of C60 to C120, which are accelerated by a multi-stage electric field acceleration system with an acceleration voltage of 100-500 volts, and the kinetic energy of the carbon cluster bundle is adjusted to a range of 5-25 electron volts.

[0010] Preferably, the local bias voltage is applied through a controllable micro-electrode array, the minimum resolution of which is 50 μm × 50 μm; the negative bias voltage applied to the recessed region ranges from -150 V to -200 V, and the negative bias voltage applied to the flat region ranges from -50 V to -100 V; the negative bias voltage is applied in pulse form, with a pulse frequency of 50-500 Hz and a duty cycle of 30-70%.

[0011] Preferably, the diamond substrate surface pretreatment step includes: Soak and clean the product, immersing it in acetone, ethanol, and deionized water for 20 minutes each in sequence. Plasma cleaning uses a mixture of argon and oxygen in a volume ratio of 80:20, with a power of 50 watts and a cleaning time of 10 minutes. Surface activation treatment was performed using hydrogen plasma at a power of 200 watts for 5 minutes.

[0012] Preferably, a closed-loop feedback system is used to adjust the local bias distribution pattern in real time, and a surface morphology detection is performed every 10 minutes. The local bias distribution is dynamically adjusted according to the filling effect, and the adjustment step of the local bias is ±10 volts.

[0013] Preferably, the temperature of the diamond substrate is controlled at 600±20 degrees Celsius, and the beam current density of the carbonaceous cluster bundle is 0.5-2.0×10⁻⁶. 15 Individuals per square centimeter per second, with a background pressure of 2 × 10⁻⁶. -4 Pascal, processing time is 30-180 minutes.

[0014] Preferably, after the carbonaceous clusters are deposited, the diamond substrate undergoes a surface quality enhancement treatment, including: Hydrogen plasma final treatment, with a power of 100 watts and a treatment time of 5 minutes, passivates the dangling bonds on the surface; Cool slowly to room temperature at a rate of 5 degrees Celsius per minute to reduce thermal stress.

[0015] Preferably, when processing the single-crystal diamond (100) surface, the average size of the carbonaceous cluster bundles is set to 6 nanometers, the energy is 15 electron volts, the negative bias voltage of the recessed region is -180 volts, the negative bias voltage of the flat region is -70 volts, the pulse frequency is 200 Hz, and the processing time is 90 minutes, so that the surface roughness is reduced from 15 nanometers to 0.8 nanometers.

[0016] Preferably, the carbon cluster bundle comprises multi-energy clusters of different energies, generated by a dual-energy cluster source system, including high-energy carbon clusters with energies of 15-25 eV and low-energy carbon clusters with energies of 5-15 eV. The high-energy carbon clusters are mainly responsible for surface polishing, and the low-energy carbon clusters are mainly responsible for high-quality growth. The dual-energy cluster source system is implemented by two independently controlled radio frequency plasma-assisted magnetron sputtering devices and is equipped with an independent acceleration voltage regulation system.

[0017] The integrated diamond growth and polishing method based on cluster bundles and local substrate bias provided by this invention has the following beneficial effects: 1. It achieves the integration of growth and polishing, simplifies the process, significantly reduces processing time and costs, and improves production efficiency; 2. Through the synergistic effect of cluster bundles and local bias voltage, precise control of the micro-region morphology of diamond surface is achieved, and the surface roughness can be controlled at the sub-nanometer level (Ra=0.8nm), which is far superior to the traditional mechanical polishing method (Ra≤3nm). 3. It avoids subsurface damage caused by mechanical polishing, maintains the integrity of diamond crystals, and improves the overall performance of the material; 4. By using physical methods instead of traditional chemical methods, the use of chemical reagents is reduced, making it more environmentally friendly and safer; 5. By precisely controlling the local bias voltage, directional deposition is achieved, which can specifically fill the surface depression areas, improving processing efficiency and accuracy; 6. The synergistic effect of multi-energy clusters was achieved, with high-energy clusters responsible for polishing and low-energy clusters responsible for growth, forming a good synergistic effect and further improving the surface quality of diamond. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0019] The core principle of this invention, based on the integrated diamond growth and polishing method using cluster bundles and localized substrate bias, is to utilize the energy-surface interaction mechanism of carbon clusters and the directional control of cluster deposition by localized bias to achieve the integration of surface growth and polishing. The specific working principle is as follows: 1. Cluster Energy Regulation Mechanism: The interaction mechanism between carbon clusters with different energies and the diamond surface varies. When the cluster energy is low (<10 eV), the clusters mainly diffuse and recombine on the surface, which is conducive to ordered growth. When the cluster energy is moderate (10-20 eV), the clusters can achieve soft landing and cause local reconstruction, which can fill small surface defects. When the cluster energy is high (>20 eV), the collision between the clusters and the surface leads to short-range migration and rearrangement of surface atoms, which can effectively fill larger surface depressions. By precisely controlling the cluster energy, fine-grained control of the surface morphology can be achieved.

[0020] 2. Local Bias Guidance Mechanism: Charged carbon clusters experience forces under an electric field. Applying a negative bias to the surface generates a local electric field, which attracts the charged clusters. The electric field strength is proportional to the bias voltage. By designing different local bias voltage distributions, directional deposition of cluster bundles can be achieved. Applying a larger negative bias voltage to surface depressions increases the deposition probability of high-energy clusters in those areas, accelerating the leveling process; applying a smaller negative bias voltage to flat surface areas maintains uniform deposition of low-energy clusters, promoting ordered epitaxial growth.

[0021] 3. Integrated Growth and Polishing Synergistic Effect: In traditional methods, growth and polishing are two independent processes. This invention controls the energy distribution of clusters through local bias voltage, allowing high-energy clusters to preferentially fill the recessed areas (acting as "polishing"), while low-energy clusters are arranged in an orderly manner in the flat areas (acting as "growth"). This achieves the integration of growth and polishing, greatly improving processing efficiency and surface quality.

[0022] Example 1: Integrated growth and polishing of single-crystal diamond (100) facets In this embodiment, an integrated diamond growth and polishing method based on cluster bundles and local substrate bias is used to process the surface of single-crystal diamond (100). The specific steps are as follows: (1) A type IIa natural diamond with dimensions of 5mm×5mm×2mm was selected as the substrate, with an initial surface roughness Ra=15nm. The diamond substrate was first pretreated, including: immersion in acetone, ethanol and deionized water for 20 minutes each for cleaning; then cleaning with argon and oxygen mixed gas (volume ratio 80:20) plasma at 50W power for 10 minutes; and finally surface activation treatment with hydrogen plasma at 200W power for 5 minutes.

[0023] (2) The surface morphology of the diamond substrate was scanned using an atomic force microscope (AFM). The scanning range was set to 100 μm × 100 μm, and the scanning resolution was 512 × 512 pixels. Based on the scanning results, a three-dimensional surface morphology map was constructed, and the concave and flat areas of the surface were determined using height analysis software. The analysis showed that approximately 25% of the diamond surface was concave, with a depth between 5 and 20 nm.

[0024] (3) Based on the three-dimensional surface topography, a local bias distribution pattern was designed, and a controllable micro-area electrode array (resolution 50 μm × 50 μm) was used to apply a local bias to the diamond substrate. For the recessed areas, a negative bias of -180 V was applied; for the flat areas, a negative bias of -70 V was applied. The bias was applied in pulse form, with a pulse frequency set to 200 Hz and a duty cycle of 50%.

[0025] (4) Carbonaceous clusters were generated using a radio frequency plasma-assisted magnetron sputtering system. The specific parameters of the system were: operating frequency 8.56 MHz, power 1000 W, high-purity graphite (99.999% purity) as the target material, sputtering in a mixed atmosphere of argon and methane (volume ratio 95:5), and sputtering chamber pressure controlled at 5 Pascals. The generated carbonaceous clusters mainly consisted of C60-C90, with an average size of approximately 6 nanometers.

[0026] (5) A multi-stage electric field acceleration system was used to accelerate the carbonaceous cluster beams. The acceleration voltage was set to 300 volts, keeping the kinetic energy of the cluster beams at approximately 15 electron volts. The beam current density of the cluster beams was controlled at 1.5 × 10⁻⁶. 15 Individuals per square centimeter per second, with a background pressure of 2 × 10⁻⁶. -4 Pascal.

[0027] (6) The temperature of the diamond substrate was controlled at 600±5 degrees Celsius, and the processing time was 90 minutes. During the processing, the surface morphology was checked every 10 minutes, and the local bias voltage distribution was dynamically adjusted according to the filling effect, with a bias voltage adjustment step of ±10 volts. Throughout the entire processing, the cluster beam intensity and energy distribution were monitored in real time to ensure processing stability.

[0028] (7) After the treatment is completed, the diamond substrate is subjected to surface quality improvement treatment, including: hydrogen plasma final treatment, with a power of 100 watts and a treatment time of 5 minutes, to passivate the surface dangling bonds; then slowly cooling to room temperature at a rate of 5 degrees Celsius / minute to reduce thermal stress.

[0029] The results showed that after 90 minutes of integrated growth and polishing, the surface roughness of the diamond decreased from the initial 15 nm to 0.8 nm, and the surface smoothness was significantly improved. Simultaneously, the surface area of ​​the diamond increased by approximately 0.5%, maintaining its single-crystal characteristics without obvious defects or cracks.

[0030] Example 2: Surface optimization treatment of polycrystalline diamond thin films In this embodiment, the method of the present invention is used to perform surface optimization treatment on CVD-grown polycrystalline diamond films. The specific operation steps are as follows: (1) A polycrystalline diamond film with dimensions of 10 mm × 10 mm × 0.5 mm and an initial surface roughness Ra = 45 nm was selected and grown by microwave plasma CVD. The surface pretreatment was performed using the same method as in Example 1.

[0031] (2) The surface morphology of the polycrystalline diamond film was scanned using an atomic force microscope with a scanning range of 200 μm × 200 μm. The analysis results showed that there were obvious grooves at the grain boundaries on the surface of the polycrystalline diamond film, with a depth between 20 and 80 nm, and the grooves accounted for about 35% of the surface area.

[0032] (3) Based on the surface morphology analysis results, design the local bias voltage distribution pattern. Apply a negative bias voltage of -200V to the grain boundary trench region; apply a negative bias voltage of -60V to the grain region. Set the pulse frequency to 300Hz and the duty cycle to 60%.

[0033] (4) Carbonaceous clusters were generated using a radio frequency plasma-assisted magnetron sputtering system with the following operating parameters: frequency 8.56 MHz, power 1200 W, target material high-purity graphite, atmosphere of argon and methane mixture (volume ratio 95:5), and sputtering chamber pressure controlled at 6 Pascals. The generated carbonaceous clusters mainly consisted of C70-C100, with an average size of approximately 8 nanometers.

[0034] (5) A multi-stage electric field acceleration system was used to accelerate the carbonaceous cluster beams. The acceleration voltage was set to 400 volts, keeping the kinetic energy of the cluster beams at approximately 20 electron volts. The beam current density of the cluster beams was controlled at 1.8 × 10⁻⁶. 15 Individuals per square centimeter per second, with a background pressure of 2 × 10⁻⁶. -4 Pascal.

[0035] (6) The temperature of the polycrystalline diamond film was controlled at 620±5 degrees Celsius, and the processing time was 120 minutes. During the processing, the surface morphology was checked every 10 minutes, and the local bias distribution was dynamically adjusted according to the filling effect.

[0036] (7) After the treatment is completed, the surface quality is improved using the same method as in Example 1.

[0037] The results show that after 120 minutes of integrated growth and polishing, the surface roughness of the polycrystalline diamond film decreased from the initial 45 nm to 5 nm, the trench depth at the grain boundaries was significantly reduced, and the surface smoothness was significantly improved. Importantly, the treated polycrystalline diamond film maintained its original grain orientation, and there were no obvious cracks at the grain boundaries.

[0038] Example 3: Integrated growth and polishing process using a dual-energy cluster source system In this embodiment, a dual-energy cluster source system is used to perform integrated growth and polishing on the surface of a single-crystal diamond (111). The specific steps are as follows: (1) A single-crystal diamond (111) surface with dimensions of 4mm×4mm×1.5mm was selected as the substrate, with an initial surface roughness Ra=22nm. Surface pretreatment was performed using the same method as in Example 1.

[0039] (2) The surface of the diamond substrate was scanned by atomic force microscopy, and a three-dimensional surface topography map was constructed based on the scanning results. The concave and flat areas were then identified.

[0040] (3) A dual-energy cluster source system is used to generate carbonaceous clusters with different energies. The system consists of two independently controlled radio frequency plasma-assisted magnetron sputtering devices, named source A and source B, respectively.

[0041] The operating parameters of source A are as follows: frequency 8.56 MHz, power 1500 W, target material is high-purity graphite, atmosphere is a mixture of argon and methane (volume ratio 95:5), and sputtering chamber pressure is controlled at 8 Pascals. The accelerating voltage is set to 450 V, generating high-energy carbon clusters with an energy of approximately 22 EV and an average size of approximately 9 nanometers, mainly consisting of C90-C120.

[0042] The operating parameters of source B are as follows: frequency 8.56 MHz, power 800 W, target material is high-purity graphite, atmosphere is a mixture of argon and methane (volume ratio 95:5), and sputtering chamber pressure is controlled at 4 Pascals. The accelerating voltage is set to 200 V, generating low-energy carbon clusters with an energy of approximately 10 electron volts and an average size of approximately 5 nanometers, mainly consisting of C60-C80.

[0043] (4) Design a local bias distribution pattern, apply a negative bias of -190V to the concave region and a negative bias of -80V to the flat region. Set the pulse frequency to 250Hz and the duty cycle to 55%.

[0044] (5) The high-energy carbon clusters generated from source A are mainly guided to the recessed region for surface polishing; the low-energy carbon clusters generated from source B are mainly guided to the flat region for high-quality growth. The total beam current density of the two cluster bundles is controlled at 2.0 × 10⁻⁶. 15 Individuals per square centimeter per second, with a background pressure of 2 × 10⁻⁶. -4 Pascal.

[0045] (6) The temperature of the diamond substrate was controlled at 610±5 degrees Celsius, and the processing time was 150 minutes. During the processing, the power ratio of the two sources and the bias voltage of each region were adjusted in real time to optimize the processing effect.

[0046] (7) After the treatment is completed, the surface quality is improved using the same method as in Example 1.

[0047] The results show that after 150 minutes of dual-energy cluster integrated processing, the surface roughness of the diamond (111) facet decreased from the initial 22 nm to 1.2 nm, and the surface smoothness was significantly improved. Compared with a single-energy cluster source, the diamond surface treated by the dual-energy cluster source system has higher quality, polishing efficiency is improved by about 30%, and the quality of the grown layer is better.

[0048] Example 4: Fine processing of small-sized diamond samples In this embodiment, the method of the present invention is used to refine small-sized diamond samples, which is particularly suitable for the fabrication of diamond quantum sensors. The specific steps are as follows: (1) A single-crystal diamond (100) facet with dimensions of 2mm×2mm×0.5mm was selected as the substrate, with an initial surface roughness Ra=8nm. Surface pretreatment was performed using the same method as in Example 1.

[0049] (2) The surface of the diamond substrate was scanned by high-resolution atomic force microscopy, and the scanning resolution was increased to 1024×1024 pixels to obtain more detailed surface morphology information.

[0050] (3) Based on the surface morphology analysis results, a high-precision local bias distribution map was designed. A micro-electrode array with a minimum resolution of 25μm×25μm was used to apply a negative bias of -160V to the concave region and a negative bias of -65V to the flat region. The pulse frequency was set to 150Hz and the duty cycle was 45%.

[0051] (4) Carbonaceous clusters were generated using a precisely controlled radio frequency plasma-assisted magnetron sputtering system. The operating parameters were: frequency 8.56 MHz, power 700 W, target material high-purity graphite, atmosphere of argon and methane mixture (volume ratio 95:5), and sputtering chamber pressure controlled at 3 Pascals. The generated carbonaceous clusters mainly consisted of C60-C80, with an average size of approximately 4 nanometers.

[0052] (5) A precisely regulated multi-stage electric field acceleration system was used to accelerate the carbonaceous cluster beams. The acceleration voltage was set to 250 volts, keeping the kinetic energy of the cluster beams at approximately 12 electron volts. The beam current density of the cluster beams was controlled at 0.8 × 10⁻⁶. 15 Individuals per square centimeter per second, with a background pressure of 1×10⁻⁶. -4 Pascal.

[0053] (6) The temperature of the diamond substrate was controlled at 580±5 degrees Celsius, and the processing time was 60 minutes. During the processing, a high-precision surface morphology inspection was performed every 5 minutes to finely adjust the local bias voltage distribution.

[0054] (7) After the treatment is completed, a low-power (80 W) hydrogen plasma is used for a final treatment for 8 minutes to more thoroughly passivate the surface dangling bonds; then the temperature is cooled to room temperature at a slower rate of 3 degrees Celsius / minute to further reduce thermal stress.

[0055] The processing results show that after 60 minutes of fine processing, the surface roughness of the small-sized diamond sample decreased from the initial 8 nm to 0.5 nm, achieving near-atomic-level smoothness. This high-quality surface is particularly suitable for the fabrication of diamond quantum sensors.

[0056] Example 5: Low-temperature integrated growth and polishing treatment In this embodiment, an integrated growth and polishing process under low-temperature conditions was explored to reduce the impact of thermal stress on the diamond crystal structure. The specific steps are as follows: (1) A single-crystal diamond (110) surface with dimensions of 6mm×6mm×2mm was selected as the substrate, with an initial surface roughness Ra=18nm. Surface pretreatment was performed using the same method as in Example 1.

[0057] (2) The surface of the diamond substrate was scanned by atomic force microscopy to identify the concave and flat areas.

[0058] (3) Based on the surface morphology analysis results, design a local bias voltage distribution pattern. Apply a negative bias voltage of -195V to the concave region and a negative bias voltage of -85V to the flat region. Set the pulse frequency to 400Hz and the duty cycle to 65%.

[0059] (4) Carbonaceous clusters were generated using a radio frequency plasma-assisted magnetron sputtering system with the following operating parameters: frequency 8.56 MHz, power 1300 W, target material high-purity graphite, atmosphere of argon and methane mixture (volume ratio 95:5), and sputtering chamber pressure controlled at 7 Pascals. The generated carbonaceous clusters mainly consisted of C80-C110, with an average size of approximately 7 nanometers.

[0060] (5) A multi-stage electric field acceleration system was used to accelerate the carbonaceous cluster beams. The acceleration voltage was set to 350 volts, keeping the kinetic energy of the cluster beams at approximately 18 electron volts. The beam current density of the cluster beams was increased to 2.2 × 10⁻⁶. 15 The density is calculated per square centimeter per second to compensate for the reduced diffusion rate under low-temperature conditions.

[0061] (6) The temperature of the diamond substrate was controlled at a lower 500±5 degrees Celsius (about 100 degrees Celsius lower than the conventional temperature), and the processing time was extended to 180 minutes to ensure sufficient surface treatment. During the processing, the surface morphology was checked every 15 minutes, and the local bias distribution was adjusted.

[0062] (7) After the treatment is completed, the surface quality is improved using the same method as in Example 1, but the cooling rate is further reduced to 2 degrees Celsius / minute to minimize thermal stress.

[0063] The results show that although the low-temperature treatment requires a longer time (180 minutes vs. the conventional 90 minutes), the surface roughness of the treated diamond can be reduced from the initial 18 nm to 1.5 nm, and the surface residual stress is significantly reduced (verified by Raman spectroscopy measurement), which is particularly advantageous for the fabrication of high-precision optical devices or quantum devices.

[0064] Example 6: Partitioning of large-area diamond thin films In this embodiment, a partitioned continuous processing technique was developed for large-area diamond films to solve the uniformity problem in processing large-size samples. The specific steps are as follows: (1) A large-area single-crystal diamond film with dimensions of 20mm×20mm×1mm was selected as the substrate, with an initial surface roughness Ra=25nm. Surface pretreatment was performed using the same method as in Example 1.

[0065] (2) The entire surface was divided into 16 sub-regions of 5mm × 5mm, and each sub-region was processed sequentially. A high-precision moving platform was used to achieve precise positioning of the sample, with a positioning accuracy better than 10 micrometers.

[0066] (3) First, the entire surface is scanned by atomic force microscopy to obtain a global surface topography map. Then, each sub-region is scanned at high resolution to obtain local fine topography information.

[0067] (4) Design an independent local bias distribution pattern for each sub-region, taking into account the boundary transition between adjacent regions. Typically, apply a negative bias of -175 volts to the concave region and a negative bias of -75 volts to the flat region. Set the pulse frequency to 350 Hz and the duty cycle to 60%.

[0068] (5) Carbonaceous clusters were generated using a large-area, uniform radio frequency plasma-assisted magnetron sputtering system. The operating parameters were: frequency 8.56 MHz, power 1400 W, target material high-purity graphite, atmosphere a mixture of argon and methane (volume ratio 95:5), and sputtering chamber pressure controlled at 6.5 Pascals. The generated carbonaceous clusters mainly consisted of C70-C100, with an average size of approximately 6.5 nanometers.

[0069] (6) A specially designed multi-stage electric field acceleration system was used to accelerate the carbonaceous cluster beam. This system has better beam current uniformity, and the accelerating voltage was set to 325 volts, keeping the kinetic energy of the cluster beam at approximately 16.5 electron volts. The beam current density of the cluster beam was controlled at 1.6 × 10⁻⁶. 15 Units per square centimeter per second, with uniformity better than ±5%.

[0070] (7) The temperature of the diamond substrate was controlled at 615±5 degrees Celsius, and the processing time for each sub-region was 100 minutes. Adjacent regions overlapped by 10% of their area to ensure seamless connection. Throughout the processing, a specially designed thermal equalization system was used to ensure that the temperature uniformity of large-area samples was better than ±3 degrees Celsius.

[0071] (8) After each sub-region is processed, local surface quality is checked to ensure the processing quality. After all sub-regions are processed, the entire sample is subjected to hydrogen plasma final treatment and slow cooling.

[0072] The results show that after partitioned continuous processing, the surface roughness of the large-area diamond film decreased from the initial 25 nm to 2.0 nm, and the transition between different regions was natural and smooth with no obvious boundary effects. The surface roughness difference between regions was controlled within ±0.3 nm, indicating that this method has good uniformity in large-area processing.

[0073] To verify the superiority of the method of the present invention, the following comparative experiment was designed: Comparative Example 1: Traditional methods using only mechanical polishing The surface of a single-crystal diamond (100) of the same specifications as in Example 1 was treated using a conventional mechanical polishing method. The specific steps are as follows: (1) Select a type IIa natural diamond with a size of 5mm×5mm×2mm as the substrate, with an initial surface roughness Ra=15nm.

[0074] (2) Mechanical polishing was performed using diamond polishing powder (particle sizes of 3 micrometers, 1 micrometer, 0.5 micrometers and 0.1 micrometers respectively). First, slow polishing was performed for 30 minutes with a low load (100 grams), then slow polishing was performed for 60 minutes with a high load (300 grams), and finally fast polishing was performed for 90 minutes with a low load (50 grams).

[0075] (3) After polishing, ultrasonically clean in acetone and ethanol for 15 minutes each, and then treat in hydrogen plasma for 5 minutes.

[0076] The results showed that after a total of 180 minutes of mechanical polishing, the surface roughness of the diamond could be reduced to 2.5 nm, but obvious scratches and subsurface damage remained on the surface. Raman spectroscopy analysis revealed lattice distortion at a depth of approximately 50-100 nm below the polished layer. Furthermore, the material loss during polishing was approximately 5 micrometers, significantly higher than the method of this invention (which resulted in virtually no material loss).

[0077] Comparative Example 2: A method using only cluster bundle deposition without local bias control Single-crystal diamond of the same specifications as in Example 1 was processed using cluster bundle deposition without local bias control. The specific steps are as follows: (1) A type IIa natural diamond with dimensions of 5mm×5mm×2mm was selected as the substrate, with an initial surface roughness Ra=15nm. Surface pretreatment was performed using the same method as in Example 1.

[0078] (2) Carbonaceous clusters were generated using the same radio frequency plasma-assisted magnetron sputtering system as in Example 1, with identical operating parameters.

[0079] (3) Instead of using local bias control, a uniform -120V negative bias is applied to the entire sample with a pulse frequency of 200Hz and a duty cycle of 50%.

[0080] (4) The temperature of the diamond substrate was controlled at 600±5 degrees Celsius and the treatment time was 90 minutes, the same as in Example 1.

[0081] (5) After the treatment is completed, the surface quality is improved using the same method as in Example 1.

[0082] The results show that, without local bias control, the deposition of clusters on the diamond surface is relatively uniform, without a preferential filling effect on recessed areas. After 90 minutes of treatment, the surface roughness only decreased from 15 nm to 6.5 nm, far less than the effect of the method of this invention (0.8 nm). In addition, there is obvious cluster accumulation on the surface, and new protrusions even appear in some areas, resulting in uneven surface roughness.

[0083] Comparative Example 3: A two-step method of conventional CVD growth followed by polishing A two-step method, consisting of conventional CVD growth followed by polishing, was used to process single-crystal diamond of the same specifications as in Example 1. The specific steps are as follows: (1) Select a type IIa natural diamond with a size of 5mm×5mm×2mm as the substrate, with an initial surface roughness Ra=15nm.

[0084] (2) First, diamond epitaxial growth was performed using microwave plasma CVD. The reaction chamber pressure was 16 kPa, the gas flow rate H2 / CH4 = 490 sccm / 10 sccm, the reaction chamber temperature was 800℃, and the growth time was 10 hours.

[0085] (3) After CVD growth, the surface roughness increases to about 40 nm, requiring polishing. The same mechanical polishing method as Comparative Example 1 was used for the process.

[0086] The results show that the surface roughness of diamond can be reduced to 2.8 nm after the two-step process, but the total processing time exceeds 15 hours, which is much longer than the method of this invention (1.5 hours). Furthermore, the mechanical polishing step in the two-step process also leads to surface scratches and subsurface damage, with significant material loss. Most importantly, the two-step process cannot achieve a synergistic effect between growth and polishing, making it difficult to simultaneously optimize growth quality and polishing quality.

[0087] Comparative Example 4: Growth Method Using High-Energy Ion Beam Assist Single-crystal diamonds of the same specifications as in Example 1 were processed using a high-energy ion beam-assisted growth method. The specific steps are as follows: (1) A type IIa natural diamond with dimensions of 5mm×5mm×2mm was selected as the substrate, with an initial surface roughness Ra=15nm. Surface pretreatment was performed using the same method as in Example 1.

[0088] (2) An argon ion beam with an energy of 500 electron volts was generated using an argon ion source to bombard the diamond surface to smooth it. The ion beam current density was 5 × 10^14 ions / cm²·s, and the processing time was 30 minutes.

[0089] (3) Then, diamond epitaxial growth was carried out using microwave plasma CVD method with the same parameters as Comparative Example 3, and the growth time was shortened to 5 hours.

[0090] The results show that while high-energy ion beam assisted growth can reduce surface roughness (to approximately 3.5 nm), high-energy ion bombardment leads to graphitization and the formation of non-diamond phases on the diamond surface, affecting material properties. Furthermore, ion beam treatment and CVD growth are two separate steps, making true integrated processing impossible.

[0091] To evaluate the effectiveness of the method of the present invention, systematic testing and analysis were conducted on the embodiments and comparative examples, mainly including the following aspects: 1. Surface Roughness Measurement: Atomic force microscopy (AFM) was used to measure the surface roughness of the diamond before and after treatment. Typical scanning parameters were: scanning range 10 μm × 10 μm, number of scanning points 512 × 512, and scanning rate 1 Hz. Five regions were randomly selected for measurement on each sample, and the average value was taken as the final result. The measurement results are shown in the table below: Example 1 15 0.8 94.7 90 Example 2 45 5 88.9 120 Example 3 22 1.2 94.5 150 Example 4 8 0.5 93.8 60 Example 5 18 1.5 91.7 180 Example 6 25 2 92 100 Comparative Example 1 15 2.5 83.3 180 Comparative Example 2 15 6.5 56.7 90 Comparative Example 3 15 2.8 81.3 >900 Comparative Example 4 15 3.5 76.7 >330 As can be seen from the table, the method of the present invention is significantly superior to the comparative method in terms of surface roughness improvement rate and processing efficiency. In particular, Examples 1 and 4 achieved sub-nanometer level surface roughness (Ra<1nm), which is crucial for the fabrication of high-precision optical and electronic devices.

[0092] 2. Surface Crystal Structure Analysis: The crystal structure of the treated diamond surface was analyzed using Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). Raman spectroscopy, employing a 532 nm laser, has a resolution better than 1 cm⁻¹, enabling the detection of non-diamond phase content and stress distribution on the diamond surface. HRTEM allows for direct observation of surface atomic arrangement and potential lattice defects.

[0093] Analysis results show that the diamond surface treated by the method of the present invention maintains a good crystal structure, with sp^3 carbon content >99.5% and no obvious non-diamond phase. The surface residual stress is less than 0.1 GPa, which is much lower than that of mechanical polishing methods (approximately 0.8-1.2 GPa). HRTEM observation shows that the surface atoms are neatly arranged, with no obvious dislocations or stacking faults, indicating that the method of the present invention does not introduce additional crystal defects.

[0094] In contrast, the samples of Comparative Example 1 (mechanical polishing) and Comparative Example 4 (high-energy ion beam assisted growth) have obvious non-diamond phases (sp^2 carbon content of about 3-5%) and high residual stress (0.8-1.5 GPa) on their surfaces, which will significantly affect the electrical and optical properties of diamond.

[0095] 3. Surface chemical composition analysis: X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical composition of the treated diamond surface. XPS analysis depth is approximately 5-10 nm, which can accurately detect the surface elemental composition and chemical state.

[0096] Analysis results show that the diamond surface treated by the method of the present invention is mainly composed of sp 3 The carbon atom composition is hybridized (>99%), with extremely low levels of surface oxygen and other impurities (<1%). The surface dangling bonds are effectively passivated after hydrogen plasma final treatment, and the CH bond ratio is >95%.

[0097] In contrast, the sample surface of Comparative Example 1 (mechanical polishing) showed a significant oxide layer with an oxygen content of approximately 3-5%, indicating that surface contamination was introduced during the mechanical polishing process. The sample surface of Comparative Example 3 (two-step method) had a higher sp^2 carbon content (approximately 2-3%), indicating that the incoordination between the CVD growth and polishing processes led to a decrease in surface quality.

[0098] 4. Surface morphology uniformity analysis: The surface morphology uniformity of large-area samples (such as in Example 6) was analyzed using an optical interference microscope. The scanning range can reach 20mm × 20mm, and the height resolution is better than 1nm, which can effectively evaluate the uniformity of large-area processing.

[0099] Analysis results show that the large-area diamond surface treated by the method of this invention exhibits good morphological uniformity, with roughness differences between different regions controlled within ±0.3 nm, and no obvious boundary effects. In contrast, the sample treated by Comparative Example 3 (two-step method) has poor surface uniformity, with roughness differences between the central and edge regions reaching 1.5-2.0 nm, mainly due to temperature and gas flow inhomogeneities during the CVD growth process.

[0100] 5. Processing Efficiency Analysis: The processing efficiency was evaluated by comparing the processing time and final results of different methods. The typical processing time of the method of this invention is 60-180 minutes, with an average roughness improvement rate of approximately 93%. In contrast, the traditional mechanical polishing method (Comparative Example 1) requires 180 minutes to achieve an 83% improvement rate, and the two-step method (Comparative Example 3) requires more than 15 hours to achieve an 81% improvement rate. This indicates that the processing efficiency of the method of this invention is improved by at least 3-5 times.

[0101] Furthermore, the method of this invention causes almost no material loss (<50nm), while mechanical polishing methods typically lose several micrometers of material layer, which is a significant advantage for precious diamond materials.

[0102] Based on the results of the above embodiments and comparative examples, the integrated diamond growth and polishing method based on cluster bundles and local substrate bias of the present invention has the following technical effects: 1. Ultra-high surface smoothness: The method of this invention can reduce the surface roughness of diamond to the sub-nanometer level (Ra=0.5-0.8nm), which is far superior to traditional methods (Ra≥2.5nm). This ultra-high smoothness is crucial for the fabrication of diamond quantum devices, high-performance optical components, and electronic devices.

[0103] The core mechanism for achieving ultra-high surface smoothness lies in the precise synergistic control of cluster energy and local bias voltage. High-energy clusters (15-25 eV) are preferentially deposited in surface depressions under a localized high negative bias voltage (-150 to -200 V), achieving precise filling of these depressions through kinetic energy conversion and surface atomic rearrangement. Simultaneously, low-energy clusters (5-15 eV), under the control of a localized low negative bias voltage (-50 to -100 V), form an ordered arrangement in the smoothed regions, promoting high-quality epitaxial growth. This synergistic effect of the dual mechanisms allows surface roughness to reach near-atomic level smoothness.

[0104] 2. Excellent crystal integrity: Unlike traditional mechanical polishing methods, the method of this invention does not introduce mechanical damage or subsurface defects, thus maintaining the integrity of the diamond crystal. Raman spectroscopy and HRTEM analysis show that the treated diamond surface maintains a high-quality crystal structure with sp^3 carbon content >99.5%, surface residual stress <0.1GPa, and no obvious dislocations or stacking faults.

[0105] This superior crystal integrity stems from the "soft processing" characteristic of the method of this invention. The energy of carbon clusters (5-25 electron volts) is far lower than that of conventional ion beams (hundreds to thousands of electron volts), insufficient to cause deep lattice damage, only inducing local rearrangement of surface atoms. In addition, the sample temperature is controlled at 500-620°C during processing, a temperature range that is conducive to the thermal diffusion and reconstruction of surface atoms, promoting defect healing and lattice repair.

[0106] 3. High-efficiency integrated processing: This invention integrates growth and polishing into a single process, significantly improving processing efficiency. Typical processing time is 60-180 minutes, far shorter than the traditional two-step method (>15 hours). Furthermore, the integrated processing avoids contamination and damage that may be introduced during process conversion, ensuring the high quality of the final product.

[0107] The integrated processing is based on the correlation between cluster energy and deposition behavior. Low-energy clusters (5-15 eV) mainly undergo ordered arrangement and epitaxial growth on the surface, playing a "growth" role; high-energy clusters (15-25 eV) mainly induce short-range migration and rearrangement of surface atoms, playing a "polishing" role. By precisely controlling the local bias voltage distribution, the spatial separation and temporal synergy of these two effects can be achieved, allowing growth and polishing to occur simultaneously, greatly improving processing efficiency.

[0108] 4. Precise Local Topography Control: The method of this invention achieves precise control of the surface micro-region topography through precise local bias voltage control. Especially for large-area samples with complex topography (such as the 20mm×20mm sample in Example 6), it can achieve differentiated treatment of different regions, ensuring the uniformity of the overall surface quality.

[0109] This precise local morphology control is based on the motion of charged clusters in an electric field. Charged clusters experience a force under the influence of an electric field, the magnitude of which is proportional to the field strength. By designing different local bias voltage distributions, complex electric field distributions can be created to guide the directional deposition of clusters. Experiments have shown that a bias voltage difference of approximately 10-20 volts can significantly alter the deposition probability of clusters, providing a powerful tool for the fine-tuning of micro-area morphology.

[0110] 5. Low-loss surface treatment: Compared with traditional mechanical polishing methods, the method of this invention causes almost no material loss (<50nm), while mechanical polishing typically results in the loss of several micrometers of material layer. This is a significant advantage for precious diamond materials, especially for thin film samples or precision devices where controlling material loss is crucial.

[0111] The low-loss characteristic stems from the "additive" polishing mechanism of this invention, which differs from traditional "removal" polishing. In traditional mechanical polishing, the mechanical action of abrasive particles removes surface protrusions, inevitably leading to material loss. However, this invention achieves surface smoothing primarily by adding material to recessed areas, while the rearrangement of surface atoms does not cause significant material loss, thus enabling ultra-low-loss surface treatment.

[0112] 6. Environmentally Friendly Processing Technology: The method of this invention mainly employs physical methods (cluster bundle deposition and local bias control), reducing the use of chemical reagents and making it more environmentally friendly and safer. In particular, compared with traditional chemical mechanical polishing (CMP), it does not require the use of corrosive chemical solutions and abrasive suspensions, greatly reducing the environmental burden and safety risks.

[0113] This invention, based on an integrated diamond growth and polishing method using cluster bundles and localized substrate bias, has broad application prospects and mainly includes the following aspects: 1. High-performance diamond electronic devices: Diamond, as a wide-bandgap semiconductor material, has unique advantages in the field of high-power, high-frequency electronic devices. The method of this invention can prepare diamond surfaces with ultra-high flatness and high crystal quality, providing an ideal material basis for the preparation of high-performance diamond electronic devices (such as field-effect transistors, Schottky diodes, etc.).

[0114] 2. Diamond Quantum Sensor: Nitrogen-vacancy (NV) centers in diamond are ideal for qubits and quantum sensors. The method of this invention is particularly suitable for preparing high-quality diamond quantum sensors. As shown in Example 4, it can achieve ultra-high flatness of Ra=0.5nm while maintaining excellent crystal integrity, which is crucial for improving the sensitivity and stability of quantum sensors.

[0115] 3. High-precision diamond optical components: Diamond possesses excellent optical properties, including broad spectral transmittance and high refractive index. The method of this invention can prepare large-area (such as 20mm × 20mm in Example 6) highly flat diamond surfaces, providing an effective way to prepare high-precision diamond optical components (such as windows, lenses, waveplates, etc.).

[0116] 4. Microelectromechanical Systems (MEMS) and Nanoelectromechanical Systems (NEMS): Diamond MEMS / NEMS possess unique advantages in sensing and actuator applications under extreme environments due to their excellent mechanical properties and chemical stability. The method of this invention can achieve precise control of micro-area morphology, making it particularly suitable for fabricating MEMS / NEMS devices with complex morphologies.

[0117] 5. Biomedical Applications: Diamond materials possess excellent biocompatibility, making them suitable for fabricating biomedical devices. The method of this invention does not use toxic chemical reagents, and the treated diamond surface has high cleanliness, making it particularly suitable for fabricating diamond devices for biomedical applications, such as biosensors and implantable electrodes.

[0118] This invention provides an integrated diamond growth and polishing method based on cluster bundles and localized substrate bias. By combining cluster bundle technology with localized substrate bias, an integrated process for diamond surface growth and polishing is achieved. This method not only simplifies the processing flow and reduces production costs, but also significantly improves diamond surface quality and growth efficiency.

[0119] Compared with existing technologies, the method of the present invention has the following significant advantages: (1) it can achieve sub-nanometer-level surface smoothness; (2) it maintains excellent crystal integrity; (3) it provides highly efficient integrated processing; (4) it allows for precise local morphology control; (5) it results in ultra-low material loss; and (6) it employs an environmentally friendly processing technology. These advantages make the method of the present invention promising for applications in high-performance diamond electronic devices, diamond quantum sensors, and high-precision optical components.

[0120] The successful development of this invention provides a new technical path for the precision machining of diamond materials, and is expected to promote the widespread application of diamond materials in high-tech fields.

[0121] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. An integrated diamond growth and polishing method based on cluster bundles and localized substrate bias, characterized in that, Includes the following steps: Select a diamond substrate and pretreat the surface of the diamond substrate; The surface of the diamond substrate was scanned using an atomic force microscope to obtain a three-dimensional surface topography image, and the surface depression and flat areas were identified. Based on the surface three-dimensional topography map, a local bias voltage distribution map is designed, and a larger negative bias voltage is distributed to the recessed area, while a smaller negative bias voltage is distributed to the flat area. Carbonaceous clusters are generated, wherein the size distribution of the carbonaceous clusters is 3-10 nanometers; A negative bias voltage corresponding to the local bias voltage distribution pattern is applied to the diamond substrate; The carbonaceous cluster bundles are guided to the surface of the diamond substrate. Under the action of the local bias voltage, the higher energy carbonaceous clusters are preferentially deposited in the recessed area, while the lower energy carbonaceous clusters are deposited in the flat area, thereby realizing the integration of diamond surface growth and polishing. The method for preparing the carbonaceous cluster bundle is as follows: using a radio frequency plasma-assisted magnetron sputtering system, with graphite as the target material, sputtering is performed in a mixed atmosphere of argon and methane. The operating frequency of the radio frequency plasma-assisted magnetron sputtering system is 8.56 MHz, the power is 500-1500 watts, the volume ratio of argon to methane is 95:5, and the pressure of the sputtering chamber is controlled at 2-8 Pascals. The local bias voltage is applied through a controllable micro-electrode array, the minimum resolution of which is 50 μm × 50 μm; the negative bias voltage applied to the recessed region ranges from -150 V to -200 V, and the negative bias voltage applied to the flat region ranges from -50 V to -100 V; the negative bias voltage is applied in pulse form, with a pulse frequency of 50-500 Hz and a duty cycle of 30-70%.

2. The integrated diamond growth and polishing method according to claim 1, characterized in that, The carbonaceous cluster bundle includes carbon clusters from C60 to C120, which are accelerated by a multi-stage electric field acceleration system with an acceleration voltage of 100-500 volts, and the kinetic energy of the carbonaceous cluster bundle is adjusted to a range of 5-25 electron volts.

3. The integrated diamond growth and polishing method according to claim 1, characterized in that, The steps of the diamond substrate surface pretreatment include: Soak and clean the product, immersing it in acetone, ethanol, and deionized water for 20 minutes each in sequence. Plasma cleaning uses a mixture of argon and oxygen in a volume ratio of 80:20, with a power of 50 watts and a cleaning time of 10 minutes. Surface activation treatment was performed using hydrogen plasma at a power of 200 watts for 5 minutes.

4. The integrated diamond growth and polishing method according to claim 1, characterized in that, A closed-loop feedback system is used to adjust the local bias voltage distribution pattern in real time. Surface morphology is detected every 10 minutes, and the local bias voltage distribution is dynamically adjusted according to the filling effect. The adjustment step of the local bias voltage is ±10 volts.

5. The integrated diamond growth and polishing method according to claim 1, characterized in that, The temperature of the diamond substrate is controlled at 600±20 degrees Celsius, and the beam current density of the carbonaceous cluster bundle is 0.5-2.0×10⁻⁶. 15 Individuals per square centimeter per second, with a background pressure of 2 × 10⁻⁶. -4 Pascal, processing time is 30-180 minutes.

6. The integrated diamond growth and polishing method according to claim 1, characterized in that, After the carbonaceous clusters are deposited, the diamond substrate undergoes a surface quality enhancement treatment, including: Hydrogen plasma final treatment, with a power of 100 watts and a treatment time of 5 minutes, passivates the dangling bonds on the surface; Cool slowly to room temperature at a rate of 5 degrees Celsius per minute to reduce thermal stress.

7. The integrated diamond growth and polishing method according to claim 1, characterized in that, When processing the single-crystal diamond (100) surface, the average size of the carbonaceous cluster bundles is set to 6 nanometers, the energy is 15 electron volts, the negative bias voltage of the recessed region is -180 volts, the negative bias voltage of the flat region is -70 volts, the pulse frequency is 200 Hz, and the processing time is 90 minutes, so that the surface roughness is reduced from 15 nanometers to 0.8 nanometers.

8. The integrated diamond growth and polishing method according to claim 1, characterized in that, The carbon cluster bundle comprises multi-energy clusters of different energies, generated by a dual-energy cluster source system. It includes high-energy carbon clusters with energies of 15-25 eV and low-energy carbon clusters with energies of 5-15 eV. The high-energy carbon clusters are mainly responsible for surface polishing, while the low-energy carbon clusters are mainly responsible for high-quality growth. The dual-energy cluster source system is implemented through two independently controlled radio frequency plasma-assisted magnetron sputtering devices, and is equipped with an independent acceleration voltage regulation system.