A method for cleaning the inner cavity of an MPCVD device

Abstract

This application discloses a method for cleaning the inner cavity of an MPCVD (Multi-Level Video Diode) device, comprising the following steps: After evacuating the inner cavity of the MPCVD device, H2 is introduced, and the microwave power supply of the MPCVD device is activated to generate plasma by exciting hydrogen gas; a heating program is executed according to the set target heating parameters, and H2, CO2, and Ar are introduced into the inner cavity of the MPCVD device in a predetermined sequence to form a mixed gas in the inner cavity, which is then used to etch the cavity; after the cavity etching is completed, the temperature of the inner cavity of the MPCVD device is reduced to a preset temperature; the inner cavity of the MPCVD device is evacuated again and the leak rate is checked; if the leak rate is less than or equal to a preset leak rate value, the cleaning of the inner cavity of the MPCVD device is completed. This cleaning method does not require disassembly of the device, enabling in-situ cleaning, effectively suppressing the generation of black line defects during subsequent diamond growth, and significantly improving the yield and quality stability of diamond products.

Description

Technical Field

[0001] This application relates to the field of diamond manufacturing technology, and more particularly to a method for cleaning the inner cavity of an MPCVD equipment. Background Technology

[0002] Microwave plasma chemical vapor deposition (MPCVD) technology has become a core technology for the preparation of high-quality single-crystal diamond due to its advantages such as high plasma purity, easily controllable energy density, and stable growth environment. During the single-crystal diamond growth process, the cleanliness of the MPCVD equipment's internal cavity, tubing, and the surfaces of each component directly affects product quality. Diamond is a polycrystalline silicon dioxide (PSD) material. 3 The hybrid structure, and the residues remaining inside the equipment during the early growth stage are mostly dense hydrocarbon mixtures. After being subjected to high temperatures, these substances will deposit on the surface of the diamond seed crystal along with the precursor, easily forming sp in the product. 2 The hybrid bonding of graphite-like materials ultimately leads to "black line" defects in diamond products, severely affecting the yield of single-crystal diamond products.

[0003] Existing technologies typically use hydrogen plasma to clean the internal cavity of equipment, which can only remove loose surface deposits and is difficult to remove dense hydrocarbon deposits formed after long-term use. The cleaning effect is limited and cannot fundamentally solve the black line defect problem.

[0004] Therefore, there is an urgent need to develop a cleaning method that can efficiently remove impurities from the internal cavity of MPCVD equipment in order to suppress the generation of black line defects in the subsequently prepared single-crystal diamond. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a cleaning method for the inner cavity of an MPCVD equipment, which can efficiently remove impurities from the inner cavity of the MPCVD equipment, thereby ensuring a clean growth environment for single crystal diamond and reducing the generation of black line defects in the subsequently prepared single crystal diamond.

[0006] To achieve one or more of the above objectives or other objectives, this application provides a method for cleaning the inner cavity of an MPCVD device, comprising the following steps:

[0007] After evacuating the inner cavity of the MPCVD equipment, H2 is introduced, and the microwave power supply of the MPCVD equipment is turned on to ignite and excite hydrogen to generate plasma.

[0008] The heating program is executed according to the set heating target parameters, and H2, CO2 and Ar are introduced into the inner cavity of the MPCVD equipment in a predetermined order to form a mixed gas in the inner cavity of the MPCVD equipment. The mixed gas is used to etch the inner cavity of the MPCVD equipment.

[0009] After the cavity etching is completed, the temperature of the MPCVD equipment cavity is reduced to a preset temperature;

[0010] The cavity of the MPCVD equipment is evacuated again and the leak rate is checked. If the leak rate is less than or equal to the preset leak rate value, the cleaning of the cavity of the MPCVD equipment is completed.

[0011] Further, the step of evacuating the internal cavity of the MPCVD equipment, introducing H2, and activating the microwave power supply of the MPCVD equipment to ignite and excite hydrogen to generate plasma includes:

[0012] Start the vacuum pump and open the coarse evacuation valve to evacuate the inner cavity of the MPCVD equipment until the inner cavity pressure drops below 1 Pa.

[0013] H2 is introduced into the inner cavity of the evacuated MPCVD equipment and continued until the gas pressure in the inner cavity reaches 1 kPa.

[0014] The microwave power supply of the MPCVD equipment is turned on, which ignites and excites the hydrogen gas in the cavity of the MPCVD equipment to generate plasma.

[0015] Further, the step of executing a heating program according to set target heating parameters and introducing H2, CO2, and Ar into the MPCVD equipment cavity in a predetermined sequence to form a mixed gas in the MPCVD equipment cavity, and then using the mixed gas to perform cavity etching on the MPCVD equipment cavity, includes:

[0016] The heating program is executed according to the set heating target parameters, which include: target temperature of 900~920℃, target power of 9~12kW, target internal cavity air pressure of 16~18kPa, and heating time of 30min.

[0017] The heating program is executed according to the heating target parameters, while H2 and Ar are continuously introduced into the MPCVD equipment cavity. The H2 flow rate is 700~900 sccm / min and the Ar flow rate is 8~12 sccm / min. After the MPCVD equipment cavity reaches the heating target parameters, it is kept at the temperature for a first time to perform the first stage cavity etching of the MPCVD equipment cavity.

[0018] After the first stage of cavity etching is completed, H2 is continuously introduced at a flow rate of 700~900 sccm / min, and CO2 is gradually introduced until the CO2 flow rate reaches 4~8 sccm / min. The Ar flow rate is then adjusted to 18~22 sccm / min to form a uniform mixture of H2, CO2, and Ar in the cavity of the MPCVD equipment. The mixture is kept at this temperature for a second duration to perform the second stage of cavity etching in the cavity of the MPCVD equipment.

[0019] Further, the step of gradually introducing CO2 until the CO2 flow rate reaches 4~8 sccm / min, and adjusting the Ar flow rate to 18~22 sccm / min, includes:

[0020] Over a period of 5 minutes, the CO2 flow rate was gradually increased from 0 to 4-8 sccm / min; and over a period of 5 minutes, the Ar flow rate was gradually increased from 8-12 sccm / min to 18-22 sccm / min.

[0021] Further, after the first stage of cavity etching is completed, H2 is continuously introduced at a flow rate of 700-900 sccm / min, CO2 is gradually introduced until the CO2 flow rate reaches 4-8 sccm / min, and the Ar flow rate is adjusted to 18-22 sccm / min, so that H2, CO2, and Ar form a uniform mixed gas in the cavity of the MPCVD equipment. The mixture is then kept at this temperature for a second duration to perform the second stage of cavity etching on the MPCVD equipment cavity. This step includes:

[0022] After the first stage of cavity etching is completed, a preset proportion of H2 is diverted as a premixed carrier gas, and the premixed carrier gas and CO2 are respectively introduced into a gas premixing device for premixing. The premixing temperature is controlled at 80~100℃, and the premixing time is 30~60s to obtain a premixed gas. During the premixing process, the CO2 flow rate is gradually increased from 0, so that the volume percentage of CO2 in the premixed gas steadily increases from 0 to 0.5%~1%.

[0023] The premixed gas, Ar and the remaining proportion of H2 are introduced into the inner cavity of the MPCVD equipment. The flow rate of the premixed gas is gradually increased over 5 minutes until the CO2 flow rate reaches 4~8 sccm / min. At the same time, the Ar flow rate is gradually increased to 18~22 sccm / min over 5 minutes, so that H2, CO2 and Ar form a uniform mixed gas in the inner cavity of the MPCVD equipment.

[0024] Maintain the flow rate of the mixed gas and keep it at 900~920°C for a second duration to complete the second stage of cavity etching.

[0025] Furthermore, the preset ratio is 10% to 40%.

[0026] Furthermore, the first duration is 20-60 minutes.

[0027] Furthermore, the second duration is 10-40 minutes.

[0028] Further, after the cavity etching is completed, the step of reducing the temperature of the MPCVD equipment cavity to a preset temperature includes:

[0029] After the cavity etching is completed, stop the introduction of CO2 and Ar, adjust the H2 flow rate to 50 sccm / min, adjust the microwave power of the MPCVD equipment to 0.8~1.2kW, and adjust the gas pressure inside the equipment cavity to 1~2kPa. Continue to run for 15~30 minutes until the temperature inside the MPCVD equipment cavity drops to the preset temperature.

[0030] Further, the step of re-vacuuming the MPCVD equipment cavity and checking the leak rate, and if the leak rate is less than or equal to a preset leak rate value, completes the cleaning of the MPCVD equipment cavity, including:

[0031] Start the vacuum pump and open the coarse evacuation valve to continuously evacuate the inner cavity of the MPCVD equipment for 1-3 hours and maintain the pressure for 0.5-2 hours;

[0032] After the pressure holding period is completed, the leakage rate of the MPCVD equipment cavity is detected, and it is determined whether the leakage rate of the MPCVD equipment cavity is less than or equal to the preset leakage rate value.

[0033] If the leak rate is less than or equal to the preset leak rate value, then the cleaning of the MPCVD equipment cavity is considered complete.

[0034] The MPCVD equipment cavity cleaning method provided in this application involves evacuating the MPCVD equipment cavity, introducing H2, activating the microwave power supply of the MPCVD equipment to ignite and excite hydrogen to generate plasma; executing a heating program according to set target heating parameters, and introducing H2, CO2, and Ar into the MPCVD equipment cavity in a predetermined sequence to form a mixed gas within the MPCVD equipment cavity, which is then used to etch the cavity; after the cavity etching is completed, the temperature of the MPCVD equipment cavity is reduced to a preset temperature; the MPCVD equipment cavity is evacuated again and the leak rate is checked; if the leak rate is less than or equal to a preset leak rate value, the cleaning of the MPCVD equipment cavity is completed. This method effectively removes dense hydrocarbon deposits from the inner wall of the cavity, pipes, and component surfaces, significantly reducing SP. 2 Residues of mixed graphite-like substances. The cleaning method of this application does not require disassembly of equipment and can achieve in-situ cleaning, which can effectively inhibit the generation of black line defects during subsequent diamond growth, and significantly improve the yield and quality stability of diamond products. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] in:

[0037] Figure 1 This is a schematic flowchart of a cleaning method for the inner cavity of an MPCVD device in one embodiment;

[0038] Figure 2 The XPS spectrum of the single-crystal diamond prepared in Example 1 is shown below.

[0039] Figure 3 The image shows the XPS spectrum of the single-crystal diamond prepared in Comparative Example 1. Detailed Implementation

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0043] Reference Figure 1 The embodiments of this application provide a method for cleaning the inner cavity of an MPCVD device, comprising the following steps:

[0044] S1: After evacuating the inner cavity of the MPCVD equipment, H2 is introduced, and the microwave power supply of the MPCVD equipment is turned on to ignite and excite hydrogen to generate plasma.

[0045] S2: Execute the heating program according to the set heating target parameters, and introduce H2, CO2 and Ar into the MPCVD equipment cavity in a predetermined order to form a mixed gas in the MPCVD equipment cavity, and perform cavity etching on the MPCVD equipment cavity through the mixed gas;

[0046] S3: After the cavity etching is completed, the temperature of the MPCVD equipment cavity is reduced to a preset temperature;

[0047] S4: Vacuum the inner cavity of the MPCVD equipment again and check the leak rate. If the leak rate is less than or equal to the preset leak rate value, the cleaning of the inner cavity of the MPCVD equipment is completed.

[0048] In this embodiment, in step S1 above, a vacuum operation is performed on the inner cavity of the MPCVD equipment to remove residual air and impurity gases in the cavity. After the vacuum level reaches the preset requirement, hydrogen gas is continuously introduced into the cavity to fill the cavity and maintain a stable gas pressure. Then, the microwave power supply of the equipment is turned on to ignite and excite the hydrogen gas in the cavity through microwave energy, causing it to ionize and form hydrogen plasma.

[0049] In step S2 above, the heating program is initiated, and the equipment power, gas pressure, and other conditions are adjusted according to the preset heating target parameters to gradually raise the cavity temperature to the target etching temperature. During the heating process and after the temperature stabilizes, H2, CO2, and Ar are introduced into the cavity in a predetermined order, and they are thoroughly mixed to form a uniform etching mixture. The synergistic effect of the mixed gas and plasma is used to etch the cavity inner wall, pipes, and component surfaces. The mixed gas is a mixture of at least two of H2, CO2, and Ar. H2 provides a reducing atmosphere, CO2 enhances etching capability, and Ar optimizes the plasma state. The combination of these three substances can efficiently decompose deposits and suppress sp. 2 The formation and residue of mixed graphite-like substances.

[0050] In step S3 above, after the cavity etching is completed, the cooling program is started. By adjusting parameters such as equipment power, gas flow rate and cavity gas pressure, the temperature inside the cavity is gradually reduced, so that the cavity smoothly transitions from a high-temperature etching state to a preset low-temperature safe state.

[0051] In step S4 above, after cooling is completed, the MPCVD equipment cavity is evacuated again. This is to further remove the reaction residue and residual gas generated by etching, and to maintain the pressure of the cavity after evacuation. The leakage rate of the cavity is then checked to determine whether the airtightness of the cavity meets the preset requirements. If the leakage rate meets the standard, the cavity cleaning is considered complete. If the leakage rate does not meet the standard, the equipment is repaired and the cleaning process of steps S1 to S3 is repeated.

[0052] The MPCVD equipment cavity cleaning method of this application, by performing the above-described process, can efficiently remove dense hydrocarbon deposits from the inner wall of the cavity, pipelines, and component surfaces, significantly reducing SP. 2Residual graphite-like substances in mixed materials. This method achieves in-situ cleaning without disassembling the equipment; the cleanliness of the cavity after cleaning meets the requirements for high-quality single-crystal diamond growth, effectively suppressing the generation of black line defects during subsequent diamond growth, and significantly improving product yield and quality stability.

[0053] In some specific embodiments, step S1, which involves evacuating the inner cavity of the MPCVD equipment, introducing H2, and activating the microwave power supply of the MPCVD equipment to ignite and excite hydrogen gas to generate plasma, includes:

[0054] Start the vacuum pump and open the coarse evacuation valve to evacuate the inner cavity of the MPCVD equipment until the inner cavity pressure drops below 1 Pa.

[0055] H2 is introduced into the inner cavity of the evacuated MPCVD equipment and continued until the gas pressure in the inner cavity reaches 1 kPa.

[0056] The microwave power supply of the MPCVD equipment is turned on, which ignites and excites the hydrogen gas in the cavity of the MPCVD equipment to generate plasma.

[0057] In some specific embodiments, step S2, which involves executing a heating program according to set target heating parameters and introducing H2, CO2, and Ar into the MPCVD equipment cavity in a predetermined sequence to form a mixed gas in the MPCVD equipment cavity, and then using the mixed gas to perform cavity etching on the MPCVD equipment cavity, includes:

[0058] S201: Execute the heating program according to the set heating target parameters, wherein the heating target parameters include: target temperature of 900~920℃, target power of 9~12kW, target internal cavity air pressure of 16~18kPa, and heating time of 30min;

[0059] S202: Execute the heating program according to the stated heating target parameters, while continuously introducing H2 and Ar into the MPCVD equipment cavity, wherein the H2 flow rate is 700~900 sccm / min and the Ar flow rate is 8~12 sccm / min, until the MPCVD equipment cavity reaches the stated heating target parameters, and then maintain the temperature for a first duration to perform the first stage of cavity etching on the MPCVD equipment cavity; in some specific embodiments, the first duration is 20~60 min;

[0060] S203: After the first stage of cavity etching is completed, H2 is continuously introduced at a flow rate of 700~900 sccm / min, and CO2 is gradually introduced until the CO2 flow rate reaches 4~8 sccm / min. The Ar flow rate is then adjusted to 18~22 sccm / min to form a uniform mixed gas of H2, CO2 and Ar in the cavity of the MPCVD equipment. The mixture is kept at this temperature for a second duration to perform the second stage of cavity etching in the cavity of the MPCVD equipment. In some specific embodiments, the second duration is 10~40 min.

[0061] In this embodiment, in step S201 above, the heating program is initiated. Through the power control module and air pressure regulation system of the equipment, the cavity temperature, power, and air pressure are gradually increased to ultimately reach the set target value. The target heating parameters can be specifically set according to the degree of adhesion of the deposits inside the MPCVD equipment cavity. For example, the target temperature can be set to 900℃, 910℃, 920℃, etc.; the target power can be set to 9kW, 10kW, 11kW, 12kW, etc.; and the target cavity air pressure can be set to 16kPa, 17kPa, 18kPa, etc.

[0062] In step S202 above, while the heating program is started, H2 and Ar are continuously introduced into the inner cavity of the equipment, and the H2 flow rate is controlled to be maintained at 700~900 sccm / min and the Ar flow rate is maintained at 8~12 sccm / min. After the various parameters of the cavity reach the target heating parameters, the temperature is maintained for a first time. The reducing atmosphere formed by H2 at high temperature can initially decompose the organic components in the hydrocarbon deposits, while Ar can optimize the morphology and density of the plasma, enlarge the diameter of the plasma fireball, and thus improve the coverage of active particles. The holding time can be flexibly adjusted according to the thickness of the deposits to ensure the initial removal of loose and some dense deposits. For example, the H2 flow rate can be set to 700 sccm / min, 800 sccm / min, 900 sccm / min, etc.; the Ar flow rate can be 8 sccm / min, 9 sccm / min, 10 sccm / min, 11 sccm / min, 12 sccm / min, etc.; the first duration can be set to 20 min, 25 min, 30 min, 35 min, 40 min, 50 min, 60 min, etc., preferably, the first duration is set to 25~35 min.

[0063] In step S203 above, after the first stage of etching is completed, the H2 flow rate is kept stable, and CO2 is gradually introduced at a gentle rate until the flow rate reaches 4-8 sccm / min; simultaneously, the Ar flow rate is increased from 8-12 sccm / min in the first stage to 18-22 sccm / min, allowing the H2, CO2, and Ar gases to fully diffuse and mix uniformly within the cavity, forming a stable etching mixture; maintaining this mixed gas atmosphere and cavity parameters unchanged, the cavity is held at temperature for a second duration to perform the second stage of etching. The three gases work synergistically to perform deep etching, thoroughly removing sp. 2 Hybrid graphite-like materials. CO2 enhances etching capabilities; its oxygen-active particles can oxidize carbonaceous deposits, disrupting the dense structure at the molecular level and significantly improving etching efficiency. However, due to the high bond energy of CO2, further increasing the Ar flow rate enhances the dissociation efficiency of the H2 and CO2 mixture. Ar atoms, under microwave energy, can enhance plasma ionization, providing energy assistance for CO2 dissociation and compensating for its high bond energy and slow dissociation. Simultaneously, the coverage area of ​​the plasma fireball is continuously expanded, allowing etching to reach all corners of the cavity, achieving comprehensive and thorough etching. Furthermore, a smooth CO2 introduction maintains stable cavity temperature, preventing wafer drift. For example, the H2 flow rate can be set to 700 sccm / min, 800 sccm / min, 900 sccm / min, etc.; the CO2 flow rate can be set to 4 sccm / min, 5 sccm / min, 6 sccm / min, 7 sccm / min, 8 sccm / min, etc.; the Ar flow rate can be set to 18 sccm / min, 19 sccm / min, 20 sccm / min, 21 sccm / min, 22 sccm / min, etc.; the second duration can be set to 10 min, 20 min, 30 min, 40 min, etc., and preferably, the first duration is set to 20~30 min.

[0064] This implementation method employs a staged etching approach to improve the efficiency and effectiveness of deposit removal, effectively reducing sp. 2 The presence of residual graphite-like substances in the mixed materials provides a clean and stable cavity environment for the subsequent high-quality growth of single-crystal diamonds.

[0065] In some specific embodiments, step S203, the step of gradually introducing CO2 until the CO2 flow rate reaches 4~8 sccm / min and adjusting the Ar flow rate to 18~22 sccm / min, includes: gradually and smoothly increasing the CO2 flow rate from 0 to 4~8 sccm / min within 5 minutes; and gradually increasing the Ar flow rate from 8~12 sccm / min to 18~22 sccm / min within 5 minutes. The slow introduction of CO2 effectively buffers the temperature fluctuations caused by CO2 entering the high-temperature cavity, avoiding wafer drift due to sudden temperature changes. It also provides sufficient mixing time for CO2 with the existing H2 and Ar in the cavity, preventing uneven etching caused by localized CO2 enrichment and ensuring uniform distribution of the oxygen-containing active particles, thus fully leveraging the enhanced etching effect. The consistent increase in Ar flow rate with the increase in CO2 flow rate ensures the stability of the gas mixing system. Simultaneously, the increase in CO2 flow rate enhances the dissociation effect, specifically addressing the problem of high CO2 bond energy and low dissociation efficiency.

[0066] In some specific embodiments, after the first stage of cavity etching is completed, H2 is continuously introduced at a flow rate of 700-900 sccm / min, and CO2 is gradually introduced until the CO2 flow rate reaches 4-8 sccm / min. The Ar flow rate is then adjusted to 18-22 sccm / min to form a uniform mixture of H2, CO2, and Ar within the MPCVD equipment cavity. This mixture is then kept at a temperature for a second duration to perform the second stage of cavity etching within the MPCVD equipment cavity. Step S203 includes:

[0067] S2031: After the first stage of cavity etching is completed, a preset proportion of H2 is diverted as a premixed carrier gas, and the premixed carrier gas and CO2 are respectively introduced into a gas premixing device for premixing. The premixing temperature is controlled at 80~100℃, and the premixing time is 30~60s to obtain a premixed gas. During the premixing process, the CO2 flow rate is gradually increased from 0, so that the volume percentage of CO2 in the premixed gas steadily increases from 0 to 0.5%~1%. In some specific embodiments, the preset proportion is 10%~40%.

[0068] S2032: The premixed gas, Ar and the remaining proportion of H2 are introduced into the inner cavity of the MPCVD equipment. The flow rate of the premixed gas is gradually increased within 5 minutes until the CO2 flow rate reaches 4~8 sccm / min. At the same time, the Ar flow rate is gradually increased to 18~22 sccm / min within 5 minutes, so that H2, CO2 and Ar form a uniform mixed gas in the inner cavity of the MPCVD equipment.

[0069] S2033: Maintain the flow rate of the mixed gas and keep it at 900~920℃ for a second duration to complete the second stage of cavity etching.

[0070] In this embodiment, in step S2031 above, after the first stage of cavity etching is completed, the total flow rate of H2 is kept stable at 700~900 sccm / min, and H2 is diverted from the total flow rate as a premixed carrier gas at a preset ratio of 10%~40%. The premixed carrier gas and the CO2 to be introduced are respectively connected to the gas premixing device, the premixing temperature in the device is set to 80~100℃, and the premixing time is controlled at 30~60s. During the premixing process, the amount of CO2 introduced is gradually increased from 0, so that the volume ratio of CO2 in the premixed gas is steadily increased to 0.5%~1%, and finally a uniformly dispersed H2-CO2 premixed gas is obtained, thereby reducing the problems of temperature fluctuation and uneven gas mixing in the cavity caused by the direct introduction of CO2.

[0071] In step S2032 above, the H2-CO2 premixed gas Ar, along with the remaining 60% to 90% of H2 (maintained together with the premixed carrier gas at a total flow rate of 700 to 900 sccm / min), is simultaneously introduced into the MPCVD equipment cavity. The flow rate control program is then activated, gradually increasing the premixed gas flow rate over 5 minutes until the total CO2 flow rate in the cavity reaches 4 to 8 sccm / min, maintaining a relatively uniform flow rate increase. Simultaneously, over 5 minutes, the Ar flow rate is gradually increased from 8 to 12 sccm / min in the first stage to 18 to 22 sccm / min, ensuring that the CO2 and Ar flow rates are kept consistent. The three gases further diffuse and fuse within the cavity, forming a stable and uniform etching mixture.

[0072] In step S2033 above, after the flow rates of H2, CO2 and Ar all reach the target values, the total flow rate of H2 is maintained at 700~900 sccm / min, the flow rate of CO2 is 4~8 sccm / min and the flow rate of Ar is 18~22 sccm / min, and the cavity temperature is kept stable at 900~920℃. The temperature is maintained for a second time (10~40min). Through the synergistic effect of the mixed gases, the dense deposits remaining on the inner wall of the cavity, pipeline and component surface are deeply etched in the second stage.

[0073] In some specific embodiments, step S3, which involves reducing the temperature of the MPCVD equipment cavity to a preset temperature after the cavity etching is completed, includes:

[0074] S301: After the cavity etching is completed, stop the introduction of CO2 and Ar, adjust the H2 flow rate to 50 sccm / min, and adjust the microwave power of the MPCVD equipment to 0.8~1.2kW, and the internal gas pressure of the equipment to 1~2kPa. Continue running for 15~30 minutes until the temperature of the MPCVD equipment cavity drops to the preset temperature. The preset temperature can be a safe operating temperature, such as room temperature to 80℃.

[0075] In some specific embodiments, step S4, which involves re-vacuuming the MPCVD equipment cavity and checking the leak rate, and if the leak rate is less than or equal to a preset leak rate value, then the cleaning of the MPCVD equipment cavity is completed, includes:

[0076] S401: Start the vacuum pump and open the roughing valve to continuously evacuate the inner cavity of the MPCVD equipment for 1~3 hours and maintain the pressure for 0.5~2 hours;

[0077] S402: After the pressure holding period is completed, the leakage rate of the MPCVD equipment cavity is detected, and it is determined whether the leakage rate of the MPCVD equipment cavity is less than or equal to the preset leakage rate value.

[0078] S403: If the leakage rate is less than or equal to the preset leakage rate value, then the cleaning of the MPCVD equipment cavity is determined to be complete.

[0079] In this embodiment, in step S401 above, after the cooling process is completed, the vacuum pump of the MPCVD equipment is started and the coarse evacuation valve is opened to perform a second vacuuming operation on the inner cavity of the equipment. The vacuuming is continued for 1 to 3 hours to ensure that the residual etching reaction residue, mixed gas and trace impurities in the cavity are completely discharged. After the vacuuming is completed, the coarse evacuation valve and the vacuum pump are closed, and the inner cavity is pressure-held for 0.5 to 2 hours to maintain the sealed state of the cavity.

[0080] In steps S402-S403 above, after the pressure holding period, the leakage rate of the MPCVD equipment cavity is detected. The actual leakage rate value is compared with the preset leakage rate value to determine whether the actual leakage rate meets the requirement of being less than or equal to the preset leakage rate value. For example, the preset leakage rate value can be set to 2.5 Pa / h. If the detected actual leakage rate value is less than or equal to the preset leakage rate value, it indicates that the airtightness of the MPCVD equipment cavity meets the preset standard, and the cleaning process of the equipment cavity is considered complete, and the single crystal diamond growth process can be started subsequently. If the detected actual leakage rate value is greater than the preset leakage rate value (e.g., 2.5 Pa / h), the equipment needs to be inspected and cleaned again.

[0081] The technical effects of this application will be illustrated below through specific embodiments and comparative examples.

[0082] Example 1:

[0083] The internal cavity of the MPCVD equipment is cleaned using the following steps:

[0084] Step 1: Start the vacuum pump of the MPCVD equipment, open the coarse evacuation valve, and evacuate the inner cavity of the equipment until the gas pressure in the inner cavity drops below 1 Pa; close the coarse evacuation valve, continuously introduce H2 into the inner cavity, and control the introduction rate to make the gas pressure in the inner cavity rise steadily to 1 kPa; start the microwave power supply of the equipment to ignite and excite the H2 in the inner cavity to generate hydrogen plasma.

[0085] Step 2: Set the H2 flow rate to 800 sccm / min, the Ar flow rate to 10 sccm / min, the target temperature to 910±10℃, the target power to 10kW, the target gas pressure to 17kPa, and the heating time to 30min; start the heating program, and after the cavity parameters reach the target parameters, maintain this state for 30min to carry out the first stage of etching.

[0086] Step 3: After the first stage of etching is completed, keep the H2 flow rate at 800 sccm / min constant and gradually introduce CO2. Within 5 minutes, gradually increase the CO2 flow rate from 0 to 5 sccm / min. Simultaneously adjust the Ar flow rate, gradually increasing it from 10 sccm / min to 20 sccm / min within 5 minutes, so that H2, CO2 and Ar form a uniform mixed gas in the cavity. Maintain this state and keep it at the temperature for 30 minutes before proceeding to the second stage of etching.

[0087] Step 4: After the second stage of etching is completed, stop the supply of CO2 and Ar, and set the cooling parameters: H2 flow rate is adjusted to 50 sccm / min, target power is 1kW, target gas pressure is 1.5kPa, and cooling time is 20min; start the cooling program, keep the above parameters unchanged, and let the cavity temperature drop steadily from the high temperature etching state to below 60℃.

[0088] Step 5: After cooling is complete, restart the vacuum pump and open the coarse evacuation valve to continuously evacuate the inner cavity for 2 hours until the ultimate vacuum is reached; turn off the vacuum pump and coarse evacuation valve, and perform pressure holding treatment on the cavity for 1 hour; after pressure holding is completed, start the leak detection device to detect the leak rate of the inner cavity; if the detected leak rate is ≤2.5Pa / h, the cavity is deemed clean and qualified.

[0089] After cleaning the internal cavity of the equipment, the automated single-crystal diamond deposition process is started:

[0090] Place the diamond seed crystal on the sample stage inside the MPCVD equipment;

[0091] Continuously introduce H2 into the inner cavity of the equipment at a flow rate of 900 sccm / min, start the microwave power supply, adjust the temperature to 850℃, power to 9.5kW, and air pressure to 16Kpa;

[0092] The surface of the diamond seed crystal in the cavity was etched using hydrogen plasma for 20 minutes to remove impurities on the seed crystal surface and activate the seed crystal growth surface.

[0093] After the seed etching is completed, the H2 flow rate is maintained at 900 sccm / min, and methane is introduced at a flow rate of 10 sccm / min. The power is 9.5 KW, the temperature is 1000℃, and the gas pressure is 16 kPa for pre-growth treatment, which lasts for 30 min.

[0094] After the pre-growth was completed, the H2 flow rate was adjusted to 1000 sccm / min, the methane flow rate to 20 sccm / min, the power to 9.5 kW, the temperature to 900 ℃, and the gas pressure to 16 kPa to remain stable. The deposition was continued for 24 h to obtain single crystal diamond.

[0095] Comparative Example 1

[0096] The difference from Example 1 is that the internal cavity of the MPCVD equipment is cleaned through the following steps:

[0097] Step 1: Use an ultra-fine lint-free cloth dampened with anhydrous ethanol to wipe the inner wall of the cavity;

[0098] Step 2: Start the vacuum pump of the MPCVD equipment, open the coarse evacuation valve, and evacuate the inner cavity of the equipment until the inner cavity pressure drops below 1 Pa; close the coarse evacuation valve, continuously introduce H2 into the inner cavity, and control the introduction rate to make the inner cavity pressure rise steadily to 1 kPa; start the microwave power supply of the equipment to ignite and excite the H2 in the inner cavity to generate hydrogen plasma.

[0099] Step 3: Set the H2 flow rate to 800 sccm / min, the target temperature to 910±10℃, the target power to 10kW, the target pressure to 17kPa, and the heating time to 30min; start the heating program, and after the cavity parameters reach the target parameters, maintain this state for 30min, and clean the inner cavity of the equipment. After cleaning, cool the cavity before use.

[0100] After cleaning the internal cavity of the equipment, the automated deposition process for single-crystal diamond is started. The deposition process for single-crystal diamond is the same as in Example 1.

[0101] X-ray photoelectron spectroscopy (XPS) was performed on the single-crystal diamonds prepared in Example 1 and Comparative Example 1, and the results are as follows: Figure 2 and Figure 3 As shown. Comparative Example 1 corresponds to Figure 3 In the middle, sp 2The high intensity of the CC characteristic peak indicates that the single-crystal diamond sample contains a significant amount of sp²-hybridized graphitic impurities. This method can only remove particles or powder adhering to the inner surface of the cavity, and is ineffective in cleaning hydrocarbons. Example 1 corresponds to... Figure 2 In the middle, the intensity of the sp² CC characteristic peak is significantly reduced, while the sp 3 The intensity of the CC characteristic peak is significantly increased, becoming the main peak, indicating that the cleaning method of this application embodiment can efficiently remove sp² mixed graphite deposits in the cavity, reduce the probability of black line defects, and improve the product yield and quality stability of single crystal diamond.

[0102] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A method for cleaning the inner cavity of an MPCVD device, characterized in that, Includes the following steps: After evacuating the inner cavity of the MPCVD equipment, H2 is introduced, and the microwave power supply of the MPCVD equipment is turned on to ignite and excite hydrogen to generate plasma. The heating program is executed according to the set heating target parameters, and H2, CO2 and Ar are introduced into the inner cavity of the MPCVD equipment in a predetermined order to form a mixed gas in the inner cavity of the MPCVD equipment. The mixed gas is used to etch the inner cavity of the MPCVD equipment. After the cavity etching is completed, the temperature of the MPCVD equipment cavity is reduced to a preset temperature; The cavity of the MPCVD equipment is evacuated again and the leak rate is checked. If the leak rate is less than or equal to the preset leak rate value, the cleaning of the cavity of the MPCVD equipment is completed.

2. The cleaning method for the inner cavity of an MPCVD device as described in claim 1, characterized in that, The steps of evacuating the internal cavity of the MPCVD equipment, introducing H2, and activating the microwave power supply of the MPCVD equipment to ignite and excite hydrogen gas to generate plasma include: Start the vacuum pump and open the coarse evacuation valve to evacuate the inner cavity of the MPCVD equipment until the inner cavity pressure drops below 1 Pa. H2 is introduced into the inner cavity of the evacuated MPCVD equipment and continued until the gas pressure in the inner cavity reaches 1 kPa. The microwave power supply of the MPCVD equipment is turned on, which ignites and excites the hydrogen gas in the cavity of the MPCVD equipment to generate plasma.

3. The cleaning method for the inner cavity of an MPCVD device as described in claim 1, characterized in that, The steps of executing a heating program according to set target heating parameters and introducing H2, CO2, and Ar into the MPCVD equipment cavity in a predetermined sequence to form a mixed gas in the MPCVD equipment cavity, and using the mixed gas to perform cavity etching on the MPCVD equipment cavity, include: The heating program is executed according to the set heating target parameters, which include: target temperature of 900~920℃, target power of 9~12kW, target internal cavity air pressure of 16~18kPa, and heating time of 30min. The heating program is executed according to the heating target parameters, while H2 and Ar are continuously introduced into the MPCVD equipment cavity. The H2 flow rate is 700~900 sccm / min and the Ar flow rate is 8~12 sccm / min. After the MPCVD equipment cavity reaches the heating target parameters, it is kept at the temperature for a first time to perform the first stage cavity etching of the MPCVD equipment cavity. After the first stage of cavity etching is completed, H2 is continuously introduced at a flow rate of 700~900 sccm / min, and CO2 is gradually introduced until the CO2 flow rate reaches 4~8 sccm / min. The Ar flow rate is then adjusted to 18~22 sccm / min to form a uniform mixture of H2, CO2, and Ar in the cavity of the MPCVD equipment. The mixture is kept at this temperature for a second duration to perform the second stage of cavity etching in the cavity of the MPCVD equipment.

4. The cleaning method for the inner cavity of an MPCVD device as described in claim 3, characterized in that, The step of gradually introducing CO2 until the CO2 flow rate reaches 4~8 sccm / min, and adjusting the Ar flow rate to 18~22 sccm / min, includes: Over a period of 5 minutes, the CO2 flow rate was gradually increased from 0 to 4-8 sccm / min; and over a period of 5 minutes, the Ar flow rate was gradually increased from 8-12 sccm / min to 18-22 sccm / min.

5. The cleaning method for the inner cavity of an MPCVD device as described in claim 3, characterized in that, After the first stage of cavity etching is completed, H2 is continuously introduced at a flow rate of 700-900 sccm / min, and CO2 is gradually introduced until the CO2 flow rate reaches 4-8 sccm / min. The Ar flow rate is then adjusted to 18-22 sccm / min to form a uniform mixture of H2, CO2, and Ar within the MPCVD equipment cavity. This mixture is then held at this temperature for a second duration to perform the second stage of cavity etching within the MPCVD equipment cavity. This process includes: After the first stage of cavity etching is completed, a preset proportion of H2 is diverted as a premixed carrier gas, and the premixed carrier gas and CO2 are respectively introduced into a gas premixing device for premixing. The premixing temperature is controlled at 80~100℃, and the premixing time is 30~60s to obtain a premixed gas. During the premixing process, the CO2 flow rate is gradually increased from 0, so that the volume percentage of CO2 in the premixed gas steadily increases from 0 to 0.5%~1%. The premixed gas, Ar and the remaining proportion of H2 are introduced into the inner cavity of the MPCVD equipment. The flow rate of the premixed gas is gradually increased over 5 minutes until the CO2 flow rate reaches 4~8 sccm / min. At the same time, the Ar flow rate is gradually increased to 18~22 sccm / min over 5 minutes, so that H2, CO2 and Ar form a uniform mixed gas in the inner cavity of the MPCVD equipment. Maintain the flow rate of the mixed gas and keep it at 900~920°C for a second duration to complete the second stage of cavity etching.

6. The cleaning method for the inner cavity of an MPCVD device as described in claim 5, characterized in that, The preset ratio is 10% to 40%.

7. The cleaning method for the inner cavity of an MPCVD device as described in claim 3, characterized in that, The first duration is 20~60 minutes.

8. The cleaning method for the inner cavity of an MPCVD device as described in claim 3, characterized in that, The second duration is 10-40 minutes.

9. The cleaning method for the inner cavity of an MPCVD device as described in claim 1, characterized in that, After the cavity etching is completed, the step of reducing the temperature of the MPCVD equipment cavity to a preset temperature includes: After the cavity etching is completed, stop the introduction of CO2 and Ar, adjust the H2 flow rate to 50 sccm / min, adjust the microwave power of the MPCVD equipment to 0.8~1.2kW, and adjust the gas pressure inside the equipment cavity to 1~2kPa. Continue to run for 15~30 minutes until the temperature inside the MPCVD equipment cavity drops to the preset temperature.

10. The cleaning method for the inner cavity of an MPCVD device as described in claim 1, characterized in that, The step of re-vacuuming the MPCVD equipment cavity and checking the leak rate, and if the leak rate is less than or equal to a preset leak rate value, then the cleaning of the MPCVD equipment cavity is completed, includes: Start the vacuum pump and open the coarse evacuation valve to continuously evacuate the inner cavity of the MPCVD equipment for 1-3 hours and maintain the pressure for 0.5-2 hours; After the pressure holding period is completed, the leakage rate of the MPCVD equipment cavity is detected, and it is determined whether the leakage rate of the MPCVD equipment cavity is less than or equal to the preset leakage rate value. If the leak rate is less than or equal to the preset leak rate value, then the cleaning of the MPCVD equipment cavity is considered complete.

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