A method for removing impurities from MPCVD bulkhead

Abstract

A method for removing impurities from the bulkhead of an MPCVD device. The present invention aims to solve the problem that impurities from the bulkhead of an MPCVD device are difficult to remove. Method for removing impurities from the bulkhead of an MPCVD device: 1. Place a sample holder on a water-cooled table to protect the water-cooled table, close the MPCVD system hatch, generate hydrogen-oxygen plasma under microwave energy excitation, and use the hydrogen-oxygen plasma to etch the interior of the cabin; 2. Wet absorbent paper with deionized water to obtain wet absorbent paper, and then attach the wet absorbent paper to the bulkhead of the MPCVD system; 3. Remove the attached absorbent paper, wet a dust-free cloth with anhydrous ethanol, and wipe the bulkhead clean; 4. Use a vacuum cleaner to clean the interior of the MPCVD system; 5. Generate hydrogen-oxygen plasma again under microwave energy excitation, and use the hydrogen-oxygen plasma to etch the interior of the cabin again. The present invention removes deposited impurities through hydrogen-oxygen plasma cleaning and deionized water infiltration, followed by alcohol wiping.

Description

Technical Field

[0001] The invention belongs to the field of material preparation, and in particular relates to a method for removing impurities from an MPCVD bulkhead. Background Art

[0002] Diamond, with its exceptional optical, thermal, and semiconductor properties, has emerged as a key building block in fields such as integrated circuits, high-frequency communications, artificial intelligence, and aerospace. Even in some extreme applications, its ultra-high physical and chemical stability has made it a critical foundational material. Diamond has been designated an emerging strategic material. The development of synthetic methods and equipment for large-scale, high-quality single-crystal diamond, in particular, is crucial for the future development of the semiconductor industry. MPCVD technology, with its clean energy source, lack of electrode contamination, high energy density, and large effective deposition area, is an ideal method for producing large-scale, high-quality single-crystal diamond. Currently, MPCVD is the most promising method for producing synthetic diamond. However, during diamond growth using MPCVD, a layer of impurities deposits on the walls of the MPCVD system. This impurity changes color from light yellow to dark brown over time, and its thickness increases continuously. Impurities on the bulkhead not only absorb impurity gases and affect the vacuum performance of the MPCVD system, but also the thin layer of impurities that fall off from the bulkhead during the growth process can easily fall onto the surface of the growth substrate, seriously affecting the normal growth process of diamond, leading to growth failure and causing huge economic losses. The current conventional pure plasma cleaning method cannot effectively clean the bulkhead and remove impurities. Therefore, there is an urgent need for a low-cost, fast and convenient impurity removal method for MPCVD equipment. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that impurities on the MPCVD equipment wall are difficult to remove, which affects the growth of CVD diamond, and to provide a method for removing impurities on the MPCVD wall.

[0004] The method for removing impurities from the MPCVD bulkhead of the present invention is implemented by the following steps:

[0005] 1. Bulkhead hydrogen-oxygen plasma cleaning:

[0006] Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6 sccm, the hydrogen flow rate to 198-194 sccm, and the pressure inside the chamber to 13-15 kPa. Generate hydrogen-oxygen plasma under microwave energy excitation, and use hydrogen-oxygen plasma to etch the interior of the chamber to complete plasma cleaning;

[0007] 2. Infiltration: After the plasma etching is completed, open the hatch, moisten the absorbent paper with deionized water to obtain moist absorbent paper, and then attach (wet compress) the moist absorbent paper to the (inner) bulkhead of the MPCVD system to make the bulkhead completely infiltrated and maintain the infiltration state for 6-14 hours;

[0008] 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the bulkhead repeatedly;

[0009] 4. Impurity cleaning: Use a vacuum cleaner to clean the interior of the MPCVD system and blow away the powdery and flake-like deposited impurities;

[0010] 5. Hydrogen-oxygen plasma re-cleaning:

[0011] A sample holder is placed on the water-cooling table to protect it, the MPCVD system hatch is closed, the oxygen flow rate is adjusted to 2-6 sccm, the hydrogen flow rate is adjusted to 198-194 sccm, and the air pressure in the cabin is adjusted to 13-15 kPa. Hydrogen-oxygen plasma is generated under microwave energy excitation, and the interior of the cabin is etched again using hydrogen-oxygen plasma to complete the MPCVD cabin wall impurity removal method.

[0012] The present invention proposes a method for removing impurities from MPCVD bulkheads through hydrogen-oxygen plasma cleaning, adsorption with deionized water tissue, and wiping with anhydrous ethanol. The method optimizes the oxygen and hydrogen ratio and gas pressure, and increases the wet application of wet absorbent paper. While conventional plasma cleaning can activate impurities adsorbed on bulkheads, it cannot directly remove them through plasma etching. The activated impurities still strongly adhere to the bulkhead, making them difficult to remove with dust-free cloths or sandpaper. The present invention, after plasma cleaning activates the impurities, wet-applies deionized water tissue to the bulkhead to fully soak the impurities. Under high humidity conditions, the adsorption of the impurities to the bulkhead is significantly reduced, resulting in large-scale shedding. Undislodged impurities are then wiped with a dust-free cloth and anhydrous ethanol, and residual powder is removed with a vacuum cleaner. After impurity removal, the bulkhead is plasma cleaned again to remove dust, inorganic compounds, and other impurities introduced during the cleaning step, completing the bulkhead cleaning.

[0013] The present invention proposes a method for removing impurities from the MPCVD cavity wall, which completes the impurity removal through hydrogen-oxygen plasma cleaning, deionized water infiltration, alcohol wiping, impurity cleaning, and hydrogen-oxygen plasma cleaning.

[0014] The MPCVD bulkhead impurity removal method of the present invention has the following beneficial effects:

[0015] 1. The process of removing impurities from the MPCVD bulkhead is simple. Through hydrogen-oxygen plasma cleaning, deionized water infiltration, and alcohol wiping, the deposited impurities with strong adsorption and extremely difficult to remove can be removed.

[0016] 2. The impurity removal effect is good and it can remove almost all the deposited impurities in the wetted areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a photo of the MPCVD bulkhead before impurities are removed in the embodiment;

[0018] Figure 2 This is a photo of wet absorbent paper attached to the bulkhead of the MPCVD system in step 2 of the embodiment;

[0019] Figure 3 This is a photo of the MPCVD cabin wall after impurities are removed in the embodiment. DETAILED DESCRIPTION

[0020] Specific embodiment 1: The method for removing impurities from the MPCVD bulkhead in this embodiment is implemented according to the following steps:

[0021] 1. Bulkhead hydrogen-oxygen plasma cleaning:

[0022] Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6 sccm, the hydrogen flow rate to 198-194 sccm, and the pressure inside the chamber to 13-15 kPa. Generate hydrogen-oxygen plasma under microwave energy excitation, and use hydrogen-oxygen plasma to etch the interior of the chamber to complete plasma cleaning;

[0023] 2. Infiltration: After the plasma etching is completed, open the hatch, moisten the absorbent paper with deionized water to obtain moist absorbent paper, and then attach (wet compress) the moist absorbent paper to the (inner) bulkhead of the MPCVD system to make the bulkhead completely infiltrated and maintain the infiltration state for 6-14 hours;

[0024] 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the bulkhead repeatedly;

[0025] 4. Impurity cleaning: Use a vacuum cleaner to clean the interior of the MPCVD system and blow away the powdery and flake-like deposited impurities;

[0026] 5. Hydrogen-oxygen plasma re-cleaning:

[0027] A sample holder is placed on the water-cooling table to protect it, the MPCVD system hatch is closed, the oxygen flow rate is adjusted to 2-6 sccm, the hydrogen flow rate is adjusted to 198-194 sccm, and the air pressure in the cabin is adjusted to 13-15 kPa. Hydrogen-oxygen plasma is generated under microwave energy excitation, and the interior of the cabin is etched again using hydrogen-oxygen plasma to complete the MPCVD cabin wall impurity removal method.

[0028] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the microwave power is controlled to be 3-3.6 kW in step 1.

[0029] Specific embodiment three: The difference between this embodiment and specific embodiment one or two is that in step one, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the cabin is adjusted to 15 kPa, the microwave power is 3.6 kW, and hydrogen-oxygen plasma is generated under microwave energy excitation.

[0030] Specific embodiment 4: The difference between this embodiment and any one of specific embodiments 1 to 3 is that in step 1, the chamber body is etched using hydrogen-oxygen plasma for 8-12 hours.

[0031] Specific embodiment 5: This embodiment differs from any one of specific embodiments 1 to 4 in that in step 2, during the process of attaching the wetted absorbent paper to the (inner) bulkhead of the MPCVD system, the absorbent paper is re-wetted with deionized water every 3-4 hours.

[0032] Specific embodiment 6: This embodiment differs from any one of specific embodiments 1 to 5 in that the infiltration state is maintained for 8-12 hours in step 2.

[0033] Specific embodiment seven: The difference between this embodiment and any one of specific embodiments one to six is ​​that in step five, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the chamber is adjusted to 15 kPa, the microwave power is 3.6 kW, and hydrogen-oxygen plasma is generated under microwave energy excitation.

[0034] Specific embodiment eight: This embodiment differs from specific embodiment seven in that the time for etching the chamber body again using hydrogen-oxygen plasma in step five is 8-12 hours.

[0035] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that the sample holder described in step 1 and step 5 is a molybdenum sample holder.

[0036] Example: The method for removing impurities from the MPCVD bulkhead of this embodiment is implemented according to the following steps:

[0037] 1. Bulkhead hydrogen-oxygen plasma cleaning:

[0038] A molybdenum sample holder was placed on the water-cooling stage to protect it. The MPCVD system hatch was closed, and the oxygen flow rate and hydrogen flow rate were adjusted to 2 sccm and 198 sccm, respectively. The pressure inside the chamber was adjusted to 15 kPa and the microwave power was 3.6 kW. Hydrogen-oxygen plasma was generated under microwave energy excitation, and the interior of the chamber was etched with hydrogen-oxygen plasma for 12 hours to complete plasma cleaning.

[0039] 2. Wetting: After the plasma etching is completed, open the hatch, moisten the medical absorbent paper with deionized water to obtain moist absorbent paper, and then attach the moist absorbent paper to the (inner) bulkhead of the MPCVD system to ensure that the bulkhead is fully wetted. Maintain the wet state for 12 hours. Re-wet the medical absorbent paper with deionized water every 4 hours to maintain a humid environment inside the cabin.

[0040] 3. Alcohol wiping: After the immersion is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the bulkhead repeatedly until all the deposited impurities adsorbed on the bulkhead are wiped off;

[0041] 4. Impurity cleaning: Use a vacuum cleaner to clean the interior of the MPCVD system chamber and blow away powdery and small-piece deposited impurities;

[0042] 5. Hydrogen-oxygen plasma re-cleaning:

[0043] A molybdenum sample holder was placed on the water-cooling table to protect it, the MPCVD system hatch was closed, the oxygen flow rate was adjusted to 2 sccm, the hydrogen flow rate was adjusted to 198 sccm, the air pressure in the cabin was adjusted to 15 kPa, the microwave power was 3.6 kW, and hydrogen-oxygen plasma was generated under the excitation of microwave energy. The interior of the cabin was etched again with hydrogen-oxygen plasma for 12 hours to complete the MPCVD cabin wall impurity removal method.

[0044] The removal effect of impurities on the MPCVD bulkhead of this embodiment is shown in Figure 1-Figure 3 As shown, if only step 1 of hydrogen-oxygen plasma cleaning is performed, the impurities still strongly adhere to the bulkhead, and the impurities on the MPCVD bulkhead cannot be removed. The MPCVD bulkhead impurity removal method of this embodiment can completely remove the dark brown impurities adsorbed on the bulkhead, restoring the bulkhead of the MPCVD system to a clean state, even to the factory state.

Claims

1. A method for removing impurities from MPCVD bulkheads, characterized in that The method for removing impurities from the MPCVD bulkhead is implemented by the following steps:

1. Bulkhead hydrogen-oxygen plasma cleaning: Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6 sccm, the hydrogen flow rate to 198-194 sccm, and the pressure inside the chamber to 13-15 kPa. Generate hydrogen-oxygen plasma under microwave energy excitation, and use hydrogen-oxygen plasma to etch the interior of the chamber to complete plasma cleaning; 2. Infiltration: After the plasma etching is completed, open the hatch, wet the absorbent paper with deionized water to obtain wet absorbent paper, and then attach the wet absorbent paper to the bulkhead of the MPCVD system to make the bulkhead in a completely infiltrated state. Maintain the infiltration state for 6-14 hours; 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the bulkhead repeatedly; 4. Impurity cleaning: Use a vacuum cleaner to clean the interior of the MPCVD system and blow away the powdery deposited impurities; 5. Hydrogen-oxygen plasma re-cleaning: A sample holder is placed on the water-cooling table to protect it, the MPCVD system hatch is closed, the oxygen flow rate is adjusted to 2-6 sccm, the hydrogen flow rate is adjusted to 198-194 sccm, and the air pressure in the cabin is adjusted to 13-15 kPa. Hydrogen-oxygen plasma is generated under microwave energy excitation, and the interior of the cabin is etched again using hydrogen-oxygen plasma to complete the MPCVD cabin wall impurity removal method.

2. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 1, the microwave power is controlled to be 3-3.6 kW.

3. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 1, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the chamber is adjusted to 15 kPa, and the microwave power is 3.6 kW to generate hydrogen-oxygen plasma under microwave energy excitation.

4. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 1, the chamber body is etched using hydrogen-oxygen plasma for 8-12 hours.

5. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that During the process of attaching the wetted absorbent paper to the bulkhead of the MPCVD system in step 2, the absorbent paper was re-wetted with deionized water every 3-4 hours.

6. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 2, the infiltration state is maintained for 8-12 hours.

7. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step five, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the chamber is adjusted to 15 kPa, and the microwave power is adjusted to 3.6 kW to generate hydrogen-oxygen plasma under microwave energy excitation.

8. The method for removing impurities from the MPCVD bulkhead according to claim 7, characterized in that In step five, the chamber body is etched again using hydrogen-oxygen plasma for 8-12 hours.

9. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that The sample holders described in step 1 and step 5 are molybdenum sample holders.

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