Methods for cleaning the thin film inside the chamber of MPCVD equipment

Abstract

This application discloses a method for cleaning the thin film on the inner wall of an MPCVD equipment cavity, comprising: placing a container containing organic solvent in the cavity of the MPCVD equipment, evacuating the gas pressure inside the cavity to below 1 kPa, and maintaining this pressure for a preset time; after the vacuum in the cavity is broken, removing the cavity, heating the cavity to at least 70°C, and then cooling it to room temperature; using a vaporization device to spray gas tangentially along the inner wall of the cavity to peel off the thin film on the inner wall; reinstalling the treated cavity back into the MPCVD equipment, introducing hydrogen gas into the cavity and starting a microwave power supply to ionize the hydrogen gas to form hydrogen plasma, and using the hydrogen plasma to etch and remove residual impurities on the inner wall of the cavity, thus completing the cleaning of the thin film on the inner wall of the cavity. This application achieves efficient cleaning of deposited thin films without mechanical contact, avoiding damage such as scratching and bumping of the inner wall of the cavity, and ensuring the surface smoothness of the cavity; the high cleanliness of the inner wall of the cavity after cleaning is beneficial to improving the quality of the diamond products prepared subsequently.

Description

Technical Field

[0001] This application relates to the field of diamond manufacturing technology, and in particular to a method for cleaning the thin film on the inner wall of the cavity of an MPCVD equipment. Background Technology

[0002] In the process of preparing diamond using microwave plasma chemical vapor deposition (MPCVD) equipment, yellow or brownish-yellow deposit films easily adhere to the inner walls of the vacuum chamber made of stainless steel or aluminum alloy. These deposit films are prone to detaching and falling onto the surface of the diamond seed crystal during subsequent diamond growth, leading to defects such as inclusions and pits, severely reducing the yield of the prepared diamond product.

[0003] Currently, the cleaning methods for such deposit films on the inner wall of MPCVD equipment chambers are relatively limited, mainly including: applying a lint-free cloth soaked in alcohol or acetone to the surface of the deposit film, using capillary action to remove some of the deposits; however, this method is only effective for deposit films of a certain thickness, and if the initial cleaning is not thorough, it is difficult to achieve effective secondary cleaning; or, using low-hardness tools such as wood or plastic to directly scrape off the deposit film, but this method is prone to leaving scraping residues, and long-term operation will cause the deposits to accumulate repeatedly on the chamber wall, with the thickness continuously increasing, resulting in extremely low cleaning efficiency, and the operation process is time-consuming and labor-intensive.

[0004] Existing cleaning methods generally suffer from problems such as incomplete cleaning, low operating efficiency, easy to cause hidden scratch damage to the cavity wall, and high labor costs, which greatly restrict the production efficiency of MPCVD equipment and seriously affect the preparation quality and batch stability of diamond products. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a method for cleaning the thin film on the inner wall of the MPCVD equipment cavity, which can solve the problems of incomplete cleaning, low efficiency, and easy damage to the cavity in existing technologies.

[0006] To achieve one or more of the above objectives or other objectives, the first aspect of this application provides a method for cleaning the thin film on the inner wall of an MPCVD equipment cavity, comprising:

[0007] Place the container containing the organic solvent into the chamber of the MPCVD equipment, evacuate the gas pressure inside the chamber to below 1 kPa, and maintain this pressure for the preset duration.

[0008] After the vacuum in the cavity is broken, the cavity is removed, heated to 70°C or higher, and then cooled to room temperature.

[0009] A vaporization device is used to inject gas tangentially along the inner wall of the cavity, peeling off the thin film on the inner wall of the cavity;

[0010] The processed cavity is reinstalled into the MPCVD equipment. Hydrogen gas is introduced into the cavity and the microwave power supply is turned on to ionize the hydrogen gas and form hydrogen plasma. The residual impurities on the inner wall of the cavity are removed by etching with hydrogen plasma, thus completing the cleaning of the thin film on the inner wall of the cavity.

[0011] Furthermore, the step of placing the container containing the organic solvent into the cavity of the MPCVD equipment, evacuating the gas pressure inside the cavity to below 1 kPa, and maintaining this pressure for a preset time includes:

[0012] Anhydrous ethanol or acetone is selected as the organic solvent, and the volume of the organic solvent contained in the container is 30~80mL. The container containing the organic solvent is placed in the cavity of the MPCVD equipment.

[0013] After the air pressure inside the MPCVD equipment is evacuated to below 1 kPa by a vacuum pump, it is maintained for a preset time, which is greater than or equal to 2 hours.

[0014] Furthermore, the step of removing the cavity after the vacuum in the cavity is broken, heating the cavity to a temperature greater than or equal to 70°C, and then cooling it to room temperature includes:

[0015] After the vacuum in the cavity is broken, the cavity is removed and placed on the heat insulation frame;

[0016] The cavity is heated using a hot air gun, raising the temperature of the inner wall of the cavity to 70~120℃;

[0017] After heating is complete, allow the cavity to cool naturally to room temperature.

[0018] Furthermore, after the heating process is completed and the cavity is allowed to cool naturally to room temperature, the method further includes:

[0019] Repeat the steps of heating the cavity with a hot air gun to raise the temperature of the inner wall of the cavity to 70~120℃; and after heating, allowing the cavity to cool naturally to room temperature; repeat 1~3 times.

[0020] Furthermore, the step of heating the cavity with a hot air gun to raise the temperature of the inner wall of the cavity to 70~120°C includes:

[0021] A hot air gun is moved evenly along the circumferential contour of the outer side of the cavity to heat it, thereby raising the temperature of the inner wall of the cavity to 70~120℃ through heat conduction.

[0022] Furthermore, the step of using a vaporization device to tangentially inject gas along the inner wall of the cavity to peel off the thin film on the inner wall of the cavity includes:

[0023] The cleaning solvent is heated and vaporized to form steam. The steam is then injected tangentially along the inner wall of the cavity through a vaporization device at an angle of less than 45° to the inner wall of the cavity until the film on the inner wall of the cavity is peeled off.

[0024] Furthermore, the cleaning solvent is selected from deionized water and caustic soda solution.

[0025] Furthermore, the step of using a vaporization device to tangentially inject gas along the inner wall of the cavity to peel off the thin film on the inner wall of the cavity includes:

[0026] Dry ice particles with a particle size of 10~50μm are mixed with inert gas to form a flushing medium. The flushing medium is sprayed tangentially along the inner wall of the cavity through a vaporization device at a spray angle of less than 45° to the inner wall of the cavity until the film on the inner wall of the cavity is peeled off.

[0027] Furthermore, the inert gas is nitrogen or argon, and the gas pressure of the vaporization device is adjusted to 0.3~0.8MPa.

[0028] Further, the step of reinstalling the processed cavity back into the MPCVD equipment, introducing hydrogen gas into the cavity and activating the microwave power supply to ionize the hydrogen gas into hydrogen plasma, and using the hydrogen plasma to etch and remove residual impurities from the inner wall of the cavity, thus completing the thin film cleaning of the inner wall of the cavity, includes:

[0029] The processed cavity is reinstalled into the MPCVD equipment. Hydrogen gas is introduced into the cavity, and the microwave power supply is turned on to ionize the hydrogen gas to form hydrogen plasma. The temperature is raised to 850~950℃ and maintained in an etching state for 20~40 minutes to etch away residual impurities on the inner wall of the cavity, thus completing the thin film cleaning of the inner wall of the cavity.

[0030] The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity provided in this application involves placing a container filled with organic solvent inside the MPCVD equipment cavity, evacuating the gas pressure inside the cavity to below 1 kPa, and maintaining this pressure for a preset time. After the vacuum in the cavity is broken, the cavity is removed, heated to at least 70°C, and then cooled to room temperature. A vaporization device is used to spray gas tangentially along the inner wall of the cavity to peel off the thin film on the inner wall. The treated cavity is then reinstalled into the MPCVD equipment, hydrogen gas is introduced into the cavity, and a microwave power supply is activated to ionize the hydrogen gas and form hydrogen plasma. The hydrogen plasma is used to etch and remove residual impurities from the inner wall of the cavity, thus completing the cleaning of the thin film on the inner wall of the cavity. This achieves efficient cleaning of the deposited thin film without mechanical contact, avoiding damage such as scratching and bumping of the inner wall of the cavity, and ensuring the surface smoothness of the cavity. The high cleanliness of the inner wall of the cavity after cleaning is beneficial to improving the quality of the diamond products prepared subsequently. Attached Figure Description

[0031] 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.

[0032] in:

[0033] Figure 1 This is a flowchart of a method for cleaning the thin film on the inner wall of the MPCVD equipment cavity in one embodiment;

[0034] Figure 2 An image of the MPCVD equipment cavity with a brownish-yellow film adhering to its inner wall before cleaning, as shown in one embodiment.

[0035] Figure 3 This is an image of the MPCVD equipment cavity with a brownish-yellow film adhering to its inner wall after cleaning, as shown in one embodiment. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] 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. Process parameters not explicitly defined in this embodiment can be adaptively adjusted by those skilled in the art based on the specifications of the MPCVD equipment cavity and the thickness of the deposited film.

[0039] Reference Figure 1 The embodiments of this application provide a method for cleaning the thin film on the inner wall of an MPCVD equipment cavity, comprising:

[0040] S1: Place the container containing the organic solvent into the chamber of the MPCVD equipment, evacuate the gas pressure inside the chamber to below 1 kPa, and maintain it for the preset time;

[0041] S2: After the vacuum in the cavity is broken, remove the cavity, heat the cavity to 70°C or higher, and then cool it to room temperature;

[0042] S3: A vaporization device is used to inject gas tangentially along the inner wall of the cavity to peel off the film on the inner wall of the cavity;

[0043] S4: Install the processed cavity back into the MPCVD equipment, introduce hydrogen into the cavity and start the microwave power supply to ionize the hydrogen to form hydrogen plasma. Use the hydrogen plasma to etch and remove residual impurities from the inner wall of the cavity, thus completing the cleaning of the thin film on the inner wall of the cavity.

[0044] In this embodiment, in step S1 above, the adhesion between the deposited film and the cavity wall is initially weakened by the full penetration of organic solvent vapor into the interface between the deposited film and the cavity wall under negative pressure. The container is an open container placed in the center of the cavity. The vacuuming operation can first use a mechanical pump to evacuate the gas pressure in the cavity to below 10 kPa, and then use a molecular pump to finely evacuate it to below 1 kPa and maintain it for a preset time. The negative pressure environment allows the organic solvent to evaporate quickly to form a uniform vapor atmosphere, and the vapor can diffuse without dead corners in the cavity, fully penetrating into the tiny interfacial gaps between the deposited film and the cavity wall, thus breaking the adsorption force and bonding between the film and the cavity wall. In this step, the organic solvent is selected based on the principle of not corroding the cavity substrate of the MPCVD equipment (e.g., stainless steel / aluminum alloy), being easily volatile and leaving no residue. The preset time is adjusted according to the film thickness to ensure that the vapor fully penetrates.

[0045] In step S2 above, the difference in thermal expansion coefficients between the MPCVD equipment cavity substrate and the deposited film is utilized to further weaken the adhesion between the film and the cavity wall, and even induce microcracks in the film, significantly reducing the difficulty of subsequent peeling. The aforementioned vacuum breaking process restores the gas pressure inside the cavity to normal atmospheric pressure. Specifically, this can be achieved by slowly introducing a dry, inert protective gas (such as nitrogen) into the cavity, gradually restoring the gas pressure to normal atmospheric pressure. This avoids the strong airflow impact caused by rapid vacuum breaking, which could lead to localized detachment of the deposited film, and the subsequent re-adhesion of detached fragments onto the cavity wall, making cleaning difficult.

[0046] In step S3 above, the vaporization device can be a gas spray gun. The impact force of the tangential gas jet completely peels the film, weakened by the bonding forces in S1 and S2, from the cavity wall. Tangential jetting effectively prevents secondary adhesion of film fragments. During operation, the disassembled cavity is fixed on a rotatable cleanroom fixture. The nozzle of the gas spray gun is kept at a certain distance from the inner wall of the cavity, and the outlet of the spray gun is aligned with the tangential direction of the cavity wall. The spray gun is moved at a uniform speed along the circumference of the inner wall of the cavity. Simultaneously, the fixture can be rotated slowly to achieve uniform spraying across the entire circumference of the cavity wall. For cavities with complex structures such as butterfly or irregular shapes, the spray angle of the spray gun can be adjusted to maintain tangential gas jetting along the cavity wall, ensuring that the film in corners, curved surfaces, and other cleaning dead zones of the cavity can be effectively peeled off. The gas used for spraying is preferably a dry, impurity-free, high-pressure inert gas. The gas pressure is adjusted according to the film thickness to ensure effective film peeling without causing plastic deformation of the cavity wall substrate. During the spraying process, the peeled film fragments are carried out of the cavity by the tangential airflow. A negative pressure suction device can be set in the cavity operation area to collect the detached film fragments in real time, further preventing the fragments from re-attaching to the cavity wall.

[0047] In step S4 above, the trace film debris and interfacial adsorbed impurities remaining on the cavity wall after step S3 are etched to achieve high cleanliness of the cavity inner wall, meeting the cavity environment requirements for diamond preparation. After the cavity is reassembled, dry hydrogen gas is first introduced into the cavity to continuously purge the air inside. The microwave power supply is turned on to ionize the hydrogen gas in the cavity, forming a uniform hydrogen plasma. The plasma is kept in a stable state for etching. The high-energy hydrogen ions and hydrogen free radicals in the plasma are used to etch the residual impurities on the cavity wall until there are no residual impurities on the cavity inner wall. After etching is completed, the microwave power supply is turned off, and the cavity is allowed to cool naturally to room temperature.

[0048] The MPCVD equipment cavity inner wall thin film cleaning method of this application achieves efficient cleaning of deposited thin films through the above steps, without mechanical contact operation, avoiding damage such as scratching and bumping of the cavity inner wall, and ensuring the surface smoothness of the cavity; the high cleanliness of the cavity inner wall after cleaning is beneficial to improving the quality of the diamond products prepared subsequently.

[0049] In some embodiments, step S1, which involves placing a container filled with organic solvent into the cavity of an MPCVD device, evacuating the gas pressure inside the cavity to below 1 kPa, and maintaining this pressure for a preset duration, includes:

[0050] S101: Anhydrous ethanol or acetone is selected as the organic solvent, and the volume of the organic solvent contained in the container is 30~80mL. The container containing the organic solvent is placed in the cavity of the MPCVD equipment.

[0051] S102: After the air pressure inside the cavity of the MPCVD equipment is pumped down to below 1 kPa by a vacuum pump, it is maintained for a preset time, the preset time being greater than or equal to 2 hours.

[0052] In this embodiment, anhydrous ethanol or acetone possesses the characteristics of low boiling point, high volatility, no residue, and non-corrosiveness to stainless steel / aluminum alloy substrates, and exhibits good penetration ability to carbon-based deposits formed during diamond preparation. The aforementioned solvent volume range is adapted to the chamber volume of conventional MPCVD equipment on the market. The preset duration of negative pressure maintenance is ≥2 hours, and those skilled in the art can extend the maintenance duration according to the actual film thickness. For example, for thin deposit films with a thickness ≤10μm, negative pressure is maintained for 2 hours; for medium-thick films with a thickness of 10~50μm, negative pressure is maintained for 2~3 hours; and for thick films with a thickness >50μm, the maintenance duration can be extended to 3~4 hours.

[0053] In some embodiments, step S2, which involves removing the cavity after the vacuum in the cavity is broken, heating the cavity to a temperature greater than or equal to 70°C, and then cooling it to room temperature, includes:

[0054] S201: After the vacuum in the cavity is broken, remove the cavity and place it on the heat insulation frame;

[0055] S202: The cavity is heated using a hot air gun to raise the temperature of the inner wall of the cavity to 70~120℃;

[0056] S203: After heating is complete, allow the cavity to cool naturally to room temperature.

[0057] In this embodiment, a commercially available adjustable temperature hot air gun can be used. The outlet temperature of the hot air gun can be preset to 120~150℃. Due to the temperature loss during hot air transmission, this preset temperature can ultimately achieve an inner wall temperature of 70~120℃ for the cavity. During heating, the operator holds the hot air gun, keeping the nozzle at a certain distance from the cavity, and moves it at a uniform speed along the circumferential contour of the cavity, covering and heating the sides, top, and bottom of the cavity in sections, repeating the heating of each section several times. During the heating process, an infrared thermometer can be used to monitor the inner wall temperature of the cavity in real time. If the temperature of a certain area is lower than 70℃, the heating time can be extended; if it is higher than 120℃, the outlet temperature of the hot air gun can be reduced or the distance between the nozzle and the cavity wall can be increased. The aforementioned inner wall temperature range of 70~120℃ is designed based on the difference in thermal expansion coefficients between the cavity material and the carbon-based deposit. For example, the thermal expansion coefficient of stainless steel is approximately (10~20)×10 -6 / ℃, aluminum alloy is approximately 23×10 -6 / ℃, while the coefficient of thermal expansion of carbon-based deposits is (1~3)×10 -6Within this temperature range of / ℃, the difference in thermal expansion and contraction between the cavity substrate and the deposit can generate tensile stress at the interface, causing microcracks in the deposit film. If the temperature is too low, the tensile stress is not significant enough; if the temperature is too high, the deposit is prone to carbonization, which in turn enhances the bonding force with the cavity wall.

[0058] In some embodiments, after step S203 of allowing the cavity to cool naturally to room temperature after heating is completed, the method further includes:

[0059] S204: Repeat the steps of heating the cavity with a hot air gun to raise the temperature of the inner wall of the cavity to 70~120℃; and after heating, allowing the cavity to cool naturally to room temperature; repeat 1~3 times.

[0060] In this embodiment, for thick films, the thermal expansion and contraction difference between the cavity substrate and the deposited film is further amplified through the cumulative effect of multiple heating-cooling cycles, causing the microcracks at the film interface to continue to expand, weakening the bonding force, and reducing the difficulty of subsequent peeling steps.

[0061] In some embodiments, step S202, which involves heating the cavity with a hot air gun to raise the temperature of the inner wall of the cavity to 70-120°C, includes:

[0062] S2021: The hot air gun is moved evenly along the circumferential contour of the outer side of the cavity to heat it, and the temperature of the inner wall of the cavity is raised to 70~120℃ through heat conduction.

[0063] In this embodiment, the material of the MPCVD equipment cavity has good thermal conductivity. When heated along the outer side, the heat can be quickly conducted through the cavity wall to the inner wall, achieving simultaneous heating of the inner and outer walls. Compared with direct heating of the inner side, heating of the outer side provides a wider operating space. Operators do not need to go deep into the cavity to adjust the nozzle angle, reducing the difficulty of operation and avoiding damage to the cavity caused by improper operation. At the same time, it avoids the carbonization and adhesion problem caused by localized concentrated hot air blowing away the deposit film on the inner side.

[0064] In some embodiments, step S3, which involves using a vaporization device to tangentially inject gas along the inner wall of the cavity to peel off the thin film on the inner wall of the cavity, includes:

[0065] S301: The cleaning solvent is heated and vaporized to form steam. The steam is then injected tangentially along the inner wall of the cavity at a spray angle of less than 45° to the inner wall of the cavity until the film on the inner wall of the cavity is peeled off. In some embodiments, the cleaning solvent is selected from deionized water and caustic soda solution.

[0066] In this embodiment, the vaporization device can be, for example, a heatable gas spray gun. The spray gun pressure is set to, for example, 0.5 MPa, and the angle between the nozzle and the inner wall of the cavity is adjusted to less than 45° to ensure that the steam flow is tangential to the cavity wall, rather than impacting vertically. When no residual film is visually observable on the cavity wall, and the amount of debris carried by the steam flow continuously decreases to zero, it indicates that the film has been largely peeled off, and spraying can be stopped. If a corrosive solvent such as caustic soda solution is used, the operator must wear acid- and alkali-resistant gloves, goggles, and a gas mask.

[0067] In some embodiments, step S3, which involves using a vaporization device to tangentially inject gas along the inner wall of the cavity to peel off the thin film on the inner wall of the cavity, includes:

[0068] S301: Dry ice particles with a particle size of 10~50μm are mixed with inert gas to form a flushing medium. The flushing medium is sprayed along the tangential direction of the inner wall of the cavity through a vaporization device at a spray angle of less than 45° to the inner wall of the cavity until the film on the inner wall of the cavity is peeled off.

[0069] In this embodiment, the mechanical impact of dry ice particles and the instantaneous sublimation thermal shock are utilized to further optimize the film peeling effect. Simultaneously, the dry ice leaves no residue after sublimation, avoiding secondary pollution. Nitrogen (N2) or argon (Ar) can be used as the inert gas. By adjusting the dry ice particle size, it can be adapted to cavities with different structures such as cylindrical and butterfly shapes. Even films in difficult-to-clean locations such as corners can be reliably removed through the dispersed impact of the dry ice particles.

[0070] In some embodiments, the inert gas is nitrogen or argon, and the pressure of the vaporization device is adjusted to 0.3~0.8 MPa. Within this pressure range, the peeling impact force is ensured while avoiding damage to the cavity wall. For example, this pressure can be 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, or 0.8 MPa. In some embodiments, the mass mixing ratio of the dry ice particles to the inert gas is 1:50~1:200. At this mass mixing ratio, a suitable impact effect can be achieved on the film, thereby reliably peeling the film. For example, this mass mixing ratio can be 1:50, 1:100, 1:150, or 1:200.

[0071] In some embodiments, step S4, which involves reinstalling the processed cavity back into the MPCVD equipment, introducing hydrogen gas into the cavity, and activating the microwave power supply to ionize the hydrogen gas and form hydrogen plasma, and then using the hydrogen plasma to etch and remove residual impurities from the inner wall of the cavity to complete the thin film cleaning of the inner wall of the cavity, includes:

[0072] S401: Install the processed cavity back into the MPCVD equipment, introduce hydrogen into the cavity, start the microwave power supply to ionize the hydrogen to form hydrogen plasma, and heat it to 850~950℃, maintain the etching state for 20~40 minutes to etch away residual impurities on the inner wall of the cavity, and complete the thin film cleaning of the inner wall of the cavity.

[0073] This embodiment utilizes the high-energy reduction properties of hydrogen plasma to remove trace amounts of thin film debris and interfacial adsorbed impurities remaining after step S3. The etched cavity wall is free of residual impurities and has a smooth surface, ensuring plasma uniformity during subsequent diamond deposition, reducing seed defects, and improving diamond product yield.

[0074] For example Figure 2 The MPCVD equipment cavity shown, with a brownish-yellow film adhering to its inner wall, was cleaned using the following steps:

[0075] S1: Place 50 mL of anhydrous ethanol in an open container and place it in the center of the MPCVD equipment chamber. Evacuate the air pressure in the chamber to 1 kPa and maintain it for 2 hours.

[0076] S2: After breaking the vacuum, disassemble the cavity and heat the cavity to 70℃~120℃ on the inner wall using a hot air gun, then let it cool naturally to room temperature.

[0077] S3: Heat 20L of deionized water to 100℃, and use a steam gun to spray water vapor onto the cavity at a pressure of 0.5MPa. The tangential angle of the jet is less than 45°. The film is gradually peeled off, and the inner wall exposes the metal substrate.

[0078] S4: After reassembling the cavity and passing the leak test, introduce hydrogen gas, turn on the microwave power supply, ionize the hydrogen gas, and clean the oxide layer and invisible residue on the inner wall of the cavity.

[0079] Figure 3 The cleaned inner wall of the cavity shows a uniform metallic luster. This embodiment achieves non-destructive cleaning through a full-process vapor phase operation, completely avoiding scratches and bumps caused by mechanical contact. The smoothness and sealing performance of the cavity wall are intact. The cleanliness of the inner wall after cleaning reaches the atomic level, effectively reducing the seed defect rate of subsequent diamond deposition and significantly improving product yield and batch stability.

[0080] 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 thin film on the inner wall of an MPCVD equipment cavity, characterized in that, include: Place the container containing the organic solvent into the chamber of the MPCVD equipment, evacuate the gas pressure inside the chamber to below 1 kPa, and maintain this pressure for the preset duration. After the vacuum in the cavity is broken, the cavity is removed, heated to 70°C or higher, and then cooled to room temperature. A vaporization device is used to inject gas tangentially along the inner wall of the cavity, peeling off the thin film on the inner wall of the cavity; The processed cavity is reinstalled into the MPCVD equipment. Hydrogen gas is introduced into the cavity and the microwave power supply is turned on to ionize the hydrogen gas and form hydrogen plasma. The residual impurities on the inner wall of the cavity are removed by etching with hydrogen plasma, thus completing the cleaning of the thin film on the inner wall of the cavity.

2. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 1, characterized in that, The step of placing a container containing organic solvent into the cavity of the MPCVD equipment, evacuating the gas pressure inside the cavity to below 1 kPa, and maintaining this pressure for a preset time includes: Anhydrous ethanol or acetone is selected as the organic solvent, and the volume of the organic solvent contained in the container is 30~80mL. The container containing the organic solvent is placed in the cavity of the MPCVD equipment. After the air pressure inside the MPCVD equipment is evacuated to below 1 kPa by a vacuum pump, it is maintained for a preset time, which is greater than or equal to 2 hours.

3. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 1, characterized in that, The steps of removing the cavity after the vacuum in the cavity is broken, heating the cavity to a temperature greater than or equal to 70°C, and then cooling it to room temperature include: After the vacuum in the cavity is broken, the cavity is removed and placed on the heat insulation frame; The cavity is heated using a hot air gun, raising the temperature of the inner wall of the cavity to 70~120℃; After heating is complete, allow the cavity to cool naturally to room temperature.

4. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 3, characterized in that, After the heating process is completed, and the cavity is allowed to cool naturally to room temperature, the method further includes: Repeat the steps of heating the cavity with a hot air gun to raise the temperature of the inner wall of the cavity to 70~120℃; and after heating, allowing the cavity to cool naturally to room temperature; repeat 1~3 times.

5. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 3, characterized in that, The step of heating the cavity with a hot air gun to raise the temperature of the inner wall of the cavity to 70~120°C includes: A hot air gun is moved evenly along the circumferential contour of the outer side of the cavity to heat it, thereby raising the temperature of the inner wall of the cavity to 70~120℃ through heat conduction.

6. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 1, characterized in that, The step of using a vaporization device to inject gas tangentially along the inner wall of the cavity to peel off the thin film on the inner wall of the cavity includes: The cleaning solvent is heated and vaporized to form steam. The steam is then injected tangentially along the inner wall of the cavity through a vaporization device at an angle of less than 45° to the inner wall of the cavity until the film on the inner wall of the cavity is peeled off.

7. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 6, characterized in that, The cleaning solvent is selected from deionized water and caustic soda solution.

8. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 1, characterized in that, The step of using a vaporization device to inject gas tangentially along the inner wall of the cavity to peel off the thin film on the inner wall of the cavity includes: Dry ice particles with a particle size of 10~50μm are mixed with inert gas to form a flushing medium. The flushing medium is sprayed tangentially along the inner wall of the cavity through a vaporization device at a spray angle of less than 45° to the inner wall of the cavity until the film on the inner wall of the cavity is peeled off.

9. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 8, characterized in that, The inert gas is nitrogen or argon, and the gas pressure of the vaporization device is adjusted to 0.3~0.8MPa.

10. The method for cleaning the thin film on the inner wall of the MPCVD equipment cavity as described in claim 1, characterized in that, The steps of reinstalling the processed cavity back into the MPCVD equipment, introducing hydrogen gas into the cavity and activating the microwave power supply to ionize the hydrogen gas and form hydrogen plasma, and using the hydrogen plasma to etch and remove residual impurities from the inner wall of the cavity to complete the thin film cleaning of the inner wall of the cavity, include: The processed cavity is reinstalled into the MPCVD equipment. Hydrogen gas is introduced into the cavity, and the microwave power supply is turned on to ionize the hydrogen gas to form hydrogen plasma. The temperature is raised to 850~950℃ and maintained in an etching state for 20~40 minutes to etch away residual impurities on the inner wall of the cavity, thus completing the thin film cleaning of the inner wall of the cavity.

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