Method for manufacturing CVD single-crystal diamond grown in one-time for a long time

Abstract

The present invention discloses a manufacturing method of CVD single-crystal diamond for long-time one-time growth, which comprises the following steps: (1) Seed screening; (2) Seed pretreatment; (3) Using an MPCVD device for single-wafer growth, the steps are as follows: a. Place the seed on a terraced molybdenum sample substrate stage, place it in the MPCVD device, evacuate the vacuum, introduce H2, ignite and start the glow discharge to heat up to 700-780 °C, then introduce O2 for etching for 60 minutes, and then introduce CH4 and N2, with a microwave power of 8-9 kw and a gas pressure of 17-18 KPa, and maintain the temperature at 800-850 °C for 2 h; b. Adjust the microwave power to 9-9.5 kw and the gas pressure to 18-19 KPa. When the temperature reaches 850-900 °C, introduce CH4 and N2 and maintain for 30 minutes. Adjust the microwave power to 9.5-10 kw and the gas pressure to 19-20 KPa, and maintain the temperature at 1000-1030 °C. Regularly control the height of the substrate stage according to the growth rate at a set time period, regularly close the introduction of CH4, N2, and O2 for etching for 30 minutes, and then re-introduce CH4, N2, and O2 to resume growth. It realizes one-time stable growth for 700 hours, the good product rate is over 70%, and the product thickness reaches 6.0 mm.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal diamond preparation processes, and particularly to a manufacturing method of CVD single crystal diamond grown in a long-time one-time manner. Background Art

[0002] CVD single crystal diamond is prepared by chemical vapor deposition technology. It has characteristics such as high hardness, high wear resistance, and high thermal conductivity, and is widely used in fields such as artificial cultivated diamonds, tool materials, optical window materials, acoustic devices, and biosensor devices.

[0003] In the market for growing diamond-grade DEF color single crystal diamonds, the industry growth time generally can only continuously grow for 100 - 200 hours before polycrystalline cracks appear. The low yield rate is a pain point in the industry. The general growth rate of the blanks is 7 - 8 μm / h. According to the growth rate of 8 μm / h for 200 hours of growth, the growth thickness can only reach 1.6 mm at most, far from meeting the required growth thickness.

[0004] In order to obtain large-sized single crystal diamonds, the prior art uses multi-round growth. The interface layer stratification caused by multi-round growth leads to poor color and clarity of single crystal diamonds, and the risk of polycrystals or cracks increases. The product goes through a series of processes such as multiple furnace loading, furnace unloading, and cutting, resulting in a series of time and labor costs. Summary of the Invention

[0005] Aiming at the above defects, the purpose of the present invention is to propose a manufacturing method of CVD single crystal diamond grown in a long-time one-time manner, with a growth time that can reach 500 - 700 hours and a yield rate of over 70%, solving the industry pain points that the industry growth time generally can only continuously grow for 100 - 200 hours before polycrystalline cracks appear and the yield rate is low.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] A manufacturing method of CVD single crystal diamond grown in a long-time one-time manner, comprising the following steps:

[0008] (1) Seed crystal screening:

[0009] Use a defect-free CVD single crystal wafer as the seed crystal;

[0010] (2) Pretreatment of the seed crystal:

[0011] Place the seed crystal in an organic solution and then clean it;

[0012] (3) Use an MPCVD device for single crystal wafer growth, including the following steps:

[0013] a. Place the seeds in step (2) on the terraced structure molybdenum sample substrate stage, with a spacing of 1 mm between adjacent seeds, and place it on the MPCVD equipment. Evacuate to 1×10 -1 Pa or less, and introduce H 2 . Ignite and start heating up to 700 - 780 °C, then introduce O 2 to etch the seeds for 60 minutes. After that, introduce CH 4 , N 2 , and grow on the MPCVD equipment. Set the microwave power to 8 - 9 kw, the gas pressure to 17 - 18 KPa, keep the temperature at 800 - 850 °C, and maintain for 2 h;

[0014] b. Adjust the microwave power to 9 - 9.5 kw and the gas pressure to 18 - 19 KPa. At this time, due to the increase in microwave power and gas pressure, the temperature gradually rises. When the temperature reaches 850 - 900 °C, introduce CH 4 , N 2 , and maintain for 30 minutes. Adjust the microwave power to 9.5 - 10 kw, adjust the gas pressure to 19 - 20 KPa, keep the temperature at 1000 - 1030 °C, and regularly control the height of the substrate stage according to the growth rate at the set time period, so that the contact distance between the plasma ball and the seeds is kept within the set range. Regularly close the introduction of CH 4 , N 2 , O 2 . During the closing period, use H plasma for plasma etching. The microwave power used for etching is 9.5 - 10 kw, the gas pressure is 19 - 20 KPa, and the etching time is 30 minutes. After the etching is completed, re - introduce CH 4 , N 2 , O 2 to resume growth, and stably grow for 500 - 700 hours to obtain.

[0015] Furthermore, the size of the CVD single - crystal wafer selected in step (1) is 9 mm × 9 mm × 0.35 mm.

[0016] Furthermore, the cleaning step in step (2) is to soak the seeds in acetone, deionized water, and alcohol in sequence, and then perform ultrasonic cleaning. The soaking time in each cleaning medium is 30 min, and the ultrasonic cleaning time is 10 min.

[0017] Furthermore, the terraced structure molybdenum sample substrate stage used in step (3) is provided with concentric circular steps with a stepped distribution that are recessed from the outside to the inside. Each step surface of the concentric circular steps extends upward to be provided with a limiting convex ring, and the limiting convex ring is used to separate the seeds located on different step surfaces. Each step surface is also provided with partition bars along the diameter direction of the concentric circle, and the partition bars are used to separate the seeds on the same step surface.

[0018] Further, in step (3) a, the flow rate of H 2 is 400 sccm, the flow rate of O 2 is 1 sccm, the flow rate of CH 4 is 15 sccm, and the flow rate of N 2 is 0.5 sccm with a concentration of 10 ppm.

[0019] Further, in step (3) b, the flow rates of H 2 , CH 4 , N 2 , and O 2 are 400 sccm, 30 sccm, 1 sccm, and 1 sccm respectively, and the concentration of N 2 is 10 ppm.

[0020] Further, the purity of H 2 , N 2 , and O 2 described in step (3) is greater than 99.999%, and the purity of CH 4 is greater than 99.995%.

[0021] The technical solution provided by the present invention may include the following beneficial effects:

[0022] First, introducing hydrogen and oxygen can etch the crystal and clean the cavity, improving the yield. Thereafter, the flow rates of CH 4 and N 2 are halved compared to the later stage, aiming at complete low-temperature nucleation growth, ensuring the integrity of the growth terrace of the seed crystal in the later stage, and improving the yield. During the growth stage, by regularly controlling the height of the substrate stage according to the growth rate, the contact distance between the plasma sphere and the seed crystal is controlled to be within the set range. Combining with the use of a terraced structure molybdenum sample substrate stage, the common problem in the industry of excessive temperature difference between the center and the edge of the growth region is avoided, the temperature difference between the central seed crystal and the edge seed crystal is reduced, and the power and pressure are better matched. The terraced structure molybdenum sample substrate stage is provided with a limiting convex ring and a partition strip to prevent the seed crystal from drifting, falling, and contacting each other. Regularly stop introducing CH 4 , N 2 , and O 2 , and only use hydrogen to etch the seed crystal and clean the cavity, so that the single growth time of the seed crystal is increased to 500 - 700 hours, and a high production efficiency and a yield of more than 70% can be ensured. The one-time growth thickness of the product can reach 6.0 mm.

[0023] The manufacturing method proposed by the present invention solves the problems that in the CVD single - crystal wafer industry, polycrystalline fractures usually occur after only 100 - 200 hours of continuous growth, and the wafers need to be taken out of the furnace in advance, resulting in a short single - growth time, low efficiency, and color stratification caused by multiple rounds of growth. It provides a stable guarantee for the industrial production of single - crystal diamond, offers a manufacturing process route for high - end applications such as laser crystals, and gets rid of the bottleneck in this field, having high development prospects and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic cross - sectional structure diagram of a terraced - structure molybdenum sample substrate stage in an embodiment of the present invention.

[0025] Figure 2 It is a schematic top - view structure diagram of a terraced - structure molybdenum sample substrate stage in an embodiment of the present invention.

[0026] Figure 3 It is a structure diagram of a traditional molybdenum sample substrate stage.

[0027] Figure 4 It is a photo of a molybdenum substrate motion control console in an embodiment of the present invention.

[0028] Among them: concentric - circle steps 1, limiting convex rings 2, and partition strips 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0030] The working parameters of the MPCVD equipment used in the specific embodiment of the present invention are 10 kw and 2.45 GHz.

[0031] Calculation standard of the good - product rate: If polycrystals or fractures occur, it is determined as a defective product, and the rest are good products. Good - product rate = number of good products / total number.

[0032] Embodiment 1

[0033] A single - crystal diamond growth manufacturing method for increasing the CVD single - crystal diamond growth time to achieve one - time growth, specifically including the following steps:

[0034] (1) Seed crystal screening:

[0035] Use 34 CVD single - crystal wafers with a crystallographic orientation of (110) as seed crystals, and require the surface to be defect - free;

[0036] (2) Pretreatment of seed crystals:

[0037] The seed crystals were successively immersed in acetone, deionized water and alcohol, and then ultrasonically cleaned. The immersion time in each cleaning medium was 30 min, and the ultrasonic cleaning time was 10 min;

[0038] (3) Use an MPCVD device for single wafer growth:

[0039] a. Place the seed crystals obtained in step (2) in a terraced structure molybdenum sample substrate stage and place it on the MPCVD device. Evacuate to 1×10 -1 Pa or below, introduce H 2 , with a flow rate of 400 sccm. Ignite and start heating up to 700 - 780 °C, then introduce O 2 , with a flow rate of 1 sccm, etch the seed crystals for 60 minutes. After that, introduce CH 4 , N 2 , with flow rates of 15 sccm and 0.5 sccm respectively, and the N 2 concentration is 10 ppm. Grow on the MPCVD device, set the microwave power to 8 - 9 kw, the gas pressure to 17 - 18 KPa, keep the temperature at 800 - 850 °C, and maintain for 2 h;

[0040] b. Adjust the microwave power to 9 - 9.5 kw and the gas pressure to 18 - 19 KPa. At this time, due to the increase in microwave power and gas pressure, the temperature gradually rises. When the temperature reaches 850 - 900 °C, introduce CH 4 , N 2 , with flow rates of 30 sccm and 1 sccm respectively, and the N 2 concentration is 10 ppm, maintain for 30 minutes, adjust the microwave power to 9.5 - 10 kw, adjust the gas pressure to 19 - 20 KPa, and keep the temperature at 1000 - 1030 °C;

[0041] As Figure 4 shown in the molybdenum substrate motion control console, regularly control the height of the substrate stage according to the growth rate at the set time intervals, so that the contact distance between the plasma ball and the seed crystal is kept within the set range: the growth rate of this growth formula is 8.5 μm per hour, and the growth height per 24 hours is 0.0085×24 = 0.204 mm. Correspondingly, lower the target position by 0.2 mm on the molybdenum substrate stage motion control interface every 24 hours, so as to achieve an error in the contact distance between the plasma ball and the growth surface of the seed crystal of about 0.2 mm within 24 hours;

[0042] Turn off the introduction of CH 4 , N 2 , O 2 every 100 hours. During the shutdown period, use H plasma for plasma etching. The microwave power used for etching is 9.5 - 10 kw, the gas pressure is 19 - 20 KPa, the etching time is 30 minutes, and after the etching is completed, reintroduce CH4 、N 2 、O 2 Resume growth and stably grow for 700 hours. Achieve a 70% yield rate with a product thickness of 6.0 mm.

[0043] The terraced molybdenum sample substrate stage used in step (3) is as Figure 1 and Figure 2 shown. The terraced molybdenum sample substrate stage is provided with concentric circular steps 1 arranged in a stepped manner and recessed from the outside to the inside. Each step surface of the concentric circular steps 1 extends upward to be provided with a limiting convex ring 2, and the limiting convex ring 2 is used to separate the seeds located on different step surfaces. Each step surface is also provided with partition bars 3 along the diameter direction of the concentric circles, and the partition bars 3 are used to separate the seeds on the same step surface.

[0044] Example 2

[0045] A method for manufacturing single-crystal diamond growth that can improve the growth time of CVD single-crystal diamond to achieve one-time growth specifically includes the following steps:

[0046] (1) Seed screening:

[0047] Use 34 CVD single-crystal wafers with a crystallographic orientation of (110) as seeds, and require no defects on the surface;

[0048] (2) Pretreatment of seeds:

[0049] Place the seeds in acetone, deionized water, and alcohol for soaking in sequence, and then perform ultrasonic cleaning. The soaking time in each cleaning medium is 30 min, and the ultrasonic cleaning time is 10 min;

[0050] (3) Use an MPCVD device for single-crystal wafer growth:

[0051] a. Place the seeds in step (2) in the terraced molybdenum sample substrate stage and place it on the MPCVD device. Evacuate to 1×10 -1 Pa or below, introduce H 2 , with a flow rate of 400 sccm. Ignite and start heating to 700 - 780 °C, then introduce O 2 , with a flow rate of 1 sccm. Etch the seeds for 60 minutes, and then introduce CH 4 , N 2 , with flow rates of 15 sccm and 0.5 sccm respectively. The N 2 concentration is 10 ppm. Grow in the MPCVD device, set the microwave power to 8 - 9 kw, the gas pressure to 17 - 18 KPa, keep the temperature at 800 - 850 °C, and maintain for 2 h;

[0052] b. Adjust the microwave power to 9 - 9.5 kw and the air pressure to 18 - 19 KPa. At this time, due to the increase in microwave power and air pressure, the temperature gradually rises. When the temperature reaches 850 - 900 °C, introduce CH 4 , N 2 , with flow rates of 30 sccm and 1 sccm respectively, and the N 2 concentration of 10 ppm. Maintain for 30 minutes, adjust the microwave power to 9.5 - 10 kw, adjust the air pressure to 19 - 20 KPa, and maintain the temperature at 1000 - 1030 °C;

[0053] Regularly control the height of the substrate stage according to the growth rate at the set time intervals, so that the contact distance between the plasma sphere and the seed remains within the set range: The growth rate of this growth formula is 8.5 μm per hour, and the growth height per 24 hours is 0.0085 × 24 = 0.204 mm. Correspondingly, lower the target position by 0.2 mm on the motion control interface of the molybdenum substrate stage every 24 hours, so as to achieve an error in the contact distance between the plasma sphere and the growth surface of the seed of about 0.2 mm within 24 hours;

[0054] Close the introduction of CH 4 , N 2 , O 2 every 100 hours. During the closing period, use H plasma for plasma etching. The microwave power used for etching is 9.5 - 10 kw, the air pressure is 19 - 20 KPa, and the etching time is 30 minutes. After the etching is completed, re - introduce CH 4 , N 2 , O 2 to resume growth and stably grow for 500 hours.

[0055] This example uses the same conditions as in Example 1, stops growing after 500 hours, obtains a higher good product rate of 80%, and the product thickness is 4.3 mm.

[0056] Comparative Example 1

[0057] A single - crystal diamond growth manufacturing method for improving the growth time of CVD single - crystal diamond to achieve one - time growth, specifically including the following steps:

[0058] (1) Seed screening:

[0059] Use 34 CVD single - crystal wafers with a crystallographic orientation of (110) as seeds, and require no surface defects;

[0060] (2) Pretreatment of seeds:

[0061] Immerse the seeds in acetone, deionized water, and alcohol in sequence, and then perform ultrasonic cleaning. The immersion time in each cleaning medium is 30 min, and the ultrasonic cleaning time is 10 min;

[0062] (3) Single wafer growth using an MPCVD device:

[0063] a. Place the seed crystal in step (2) on a traditional molybdenum sample substrate stage and place it on the MPCVD device. Evacuate to 1×10 -1 Pa or below, introduce H 2 , with a flow rate of 400 sccm. Ignite and start heating up to 700 - 780 °C, then introduce O 2 , with a flow rate of 1 sccm. Etch the seed crystal for 60 minutes. Then introduce CH 4 , N 2 , with flow rates of 15 sccm and 0.5 sccm respectively. The N 2 concentration is 10 ppm. Grow on the MPCVD device, set the microwave power to 8 - 9 kw, the gas pressure to 17 - 18 KPa, keep the temperature at 800 - 850 °C, and maintain for 2 h;

[0064] b. Adjust the microwave power to 9 - 9.5 kw and the gas pressure to 18 - 19 KPa. At this time, due to the increase in microwave power and gas pressure, the temperature gradually rises. When the temperature reaches 850 - 900 °C, introduce CH 4 , N 2 , with flow rates of 30 sccm and 1 sccm respectively. The N 2 concentration is 10 ppm. Maintain for 30 minutes. Adjust the microwave power to 9.5 - 10 kw and the gas pressure to 19 - 20 KPa, and keep the temperature at 1000 - 1030 °C;

[0065] The growth rate of this growth recipe is 8.5 μm per hour. The growth height per 24 hours is 0.0085×24 = 0.204 mm. Correspondingly, lower the target position by 0.2 mm on the motion control interface of the molybdenum substrate stage every 24 hours, so as to achieve a contact distance error between the plasma sphere and the growth surface of the seed crystal of about 0.2 mm within 24 hours.

[0066] Turn off the introduction of CH 4 , N 2 , O 2 every 100 hours. During the shutdown period, use H plasma for plasma etching. The microwave power used for etching is 9.5 - 10 kw, the gas pressure is 19 - 20 KPa, and the etching time is 30 minutes. After the etching is completed, re - introduce CH 4 , N 2 , O 2 to resume growth for 200 hours.

[0067] In Comparative Example 1, a terraced - structure molybdenum sample substrate stage was not used. Use as Figure 3The traditional molybdenum sample substrate shown cannot avoid high temperature in the center area. As the growth time increases, the central area of ​​the molybdenum sheet grows polycrystalline and cracks at high temperature. After 200 hours of growth, the yield rate is only 62%, and the product thickness is 1.7mm.

[0068] Comparative Example 2

[0069] A method for growing and manufacturing single crystal diamond for increasing the growth time of CVD single crystal diamond to achieve one-time growth, specifically comprising the following steps:

[0070] (1) Seed Screening:

[0071] 34 CVD single crystal wafers with a crystallographic orientation of (110) were used as seeds, and the surface was required to be defect-free;

[0072] (2) Pretreatment of seed crystals:

[0073] The seed crystals were sequentially immersed in acetone, deionized water and alcohol, and then ultrasonically cleaned. The immersion time in each cleaning medium was 30 minutes, and the ultrasonic cleaning time was 10 minutes.

[0074] (3) Single wafer growth using MPCVD equipment:

[0075] a. Place the seed crystal in step (2) on the terraced molybdenum sample substrate stage and place it on the MPCVD equipment, evacuate to 1×10 -1 Pa or below, pass H 2 , flow rate is 400sccm, ignition starts, temperature rises to 700-780℃, then O 2 , the flow rate is 1 sccm, the seed is etched for 60 minutes, and then CH 4 、N 2 , the flow rates are 15sccm and 0.5sccm, respectively, N 2 The concentration was 10ppm, grown in an MPCVD device, with microwave power set to 8-9kw, gas pressure set to 17-18KPa, and the temperature maintained at 800-850℃ for 2h;

[0076] b. Adjust the microwave power to 9-9.5kw and the air pressure to 18-19kPa. At this time, due to the increase of microwave power and air pressure, the temperature gradually rises. When the temperature reaches 850-900℃, introduce CH 4 、N 2 , the flow rates are 30sccm and 1sccm respectively, N 2 The concentration is 10ppm, maintained for 30 minutes, the microwave power is adjusted to 9.5-10kw, the gas pressure is adjusted to 19-20KPa, and the temperature is maintained at 1000-1030℃;

[0077] Shut down CH every 100 hours4 , N 2 , O 2 During the period of closing the inlet of CH, N, and O, plasma etching is carried out using H plasma. The microwave power used for etching is 9.5 - 10 kw, the gas pressure is 19 - 20 KPa, and the etching time is 30 minutes. After the etching is completed, CH, N, and O are re-introduced 4 , N 2 , O 2 Growth is resumed for 200 hours.

[0078] In Comparative Example 2, the height of the substrate stage was not regularly controlled according to the growth rate. As the growth duration increased, the growth thickness of the product increased, the overall temperature increased, high-temperature polycrystal growth and cracking occurred. After growing for 200 hours, the yield was only 53%, and the product thickness was 1.7 mm.

[0079] Comparative Example 3

[0080] A single-crystal diamond growth manufacturing method for increasing the growth time of CVD single-crystal diamond to achieve one-time growth, specifically including the following steps:

[0081] (1) Seed screening:

[0082] Use 34 CVD single-crystal wafers with a crystallographic orientation of (110) as seeds, and the surface is required to be defect-free;

[0083] (2) Pretreatment of seeds:

[0084] The seeds are successively immersed in acetone, deionized water, and alcohol, and then ultrasonically cleaned. The immersion time in each cleaning medium is 30 min, and the ultrasonic cleaning time is 10 min.

[0085] (3) Use MPCVD equipment for single-crystal wafer growth:

[0086] a. Place the seeds in step (2) in a terraced structure molybdenum sample substrate stage and place it on the MPCVD equipment. Evacuate to 1×10 -1 Pa or below, introduce H 2 , with a flow rate of 400 sccm. After ignition and heating up to 700 - 780 °C, introduce O 2 , with a flow rate of 1 sccm, etch the seeds for 60 minutes, and then introduce CH 4 , N 2 , with flow rates of 15 sccm and 0.5 sccm respectively, and the N 2 concentration is 10 ppm. Grow on the MPCVD equipment, set the microwave power to 8 - 9 kw, the gas pressure to 17 - 18 KPa, keep the temperature at 800 - 850 °C, and keep it for 2 h;

[0087] b. Adjust the microwave power to 9 - 9.5 kw and the air pressure to 18 - 19 KPa. At this time, due to the increase in microwave power and air pressure, the temperature gradually rises. When the temperature reaches 850 - 900 °C, introduce CH 4 , N 2 , with flow rates of 30 sccm and 1 sccm respectively, and the N 2 concentration is 10 ppm. Keep it for 30 minutes, adjust the microwave power to 9.5 - 10 kw, and adjust the air pressure to 19 - 20 KPa, keeping the temperature at 1000 - 1030 °C;

[0088] Regularly control the height of the substrate stage according to the growth rate at the set time intervals, so that the contact distance between the plasma sphere and the seed crystal remains within the set range: The growth rate of this growth formula is 8.5 μm per hour, and the growth height per 24 hours is 0.0085×24 = 0.204 mm. Correspondingly, lower the target position by 0.2 mm on the motion control interface of the molybdenum substrate stage every 24 hours, so as to achieve an error in the contact distance between the plasma sphere and the growth surface of the seed crystal of about 0.2 mm within 24 hours, and grow for 200 hours.

[0089] In Comparative Example 3, CH 4 , N 2 , and O 2 were not regularly turned off, and only H plasma was used to etch the seed crystal and clean the cavity. As the growth time increased, the by - product impurities and foreign objects in the furnace increased, and the probability of falling on the seed crystal increased. After growing for 200 hours, the yield rate was only 65%, and the product thickness was 1.7 mm.

[0090] The technical features of the above - described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above - described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0091] The above - described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for producing CVD single crystal diamond grown in one go for a long time, characterized in that: The steps include: (1) Seed Screening: Use defect-free CVD single crystal wafer as seed; (2) Pretreatment of seed crystals: placing the seed crystal in an organic solution and then washing it; (3) Using MPCVD equipment to grow a single wafer, including the following steps: a. Place the seed crystals in step (2) on the terraced molybdenum sample substrate stage, with a distance of 1 mm between two adjacent seed crystals, and place them on the MPCVD equipment, evacuate to 1×10 -1 Pa or less, introduce H2, ignite and heat to 700-780℃, then introduce O2 to etch the seed for 60 minutes, then introduce CH4 and N2, grow in MPCVD equipment, set microwave power to 8-9kw, gas pressure to 17-18KPa, keep temperature at 800-850℃, and maintain for 2h; Among them, the flow rate of H2 is 400sccm, the flow rate of O2 is 1sccm, the flow rate of CH4 is 15sccm, the flow rate of N2 is 0.5sccm and the concentration is 10ppm; b. Adjust the microwave power to 9-9.5kw and the air pressure to 18-19KPa. At this time, due to the increase of microwave power and air pressure, the temperature gradually rises. When the temperature reaches 850-900°C, introduce CH4 and N2, and keep it for 30 minutes. Adjust the microwave power to 9.5-10kw, adjust the air pressure to 19-20KPa, and keep the temperature at 1000-1030°C. According to the set time period, the height of the substrate stage is regularly controlled according to the growth rate so that the contact distance between the plasma ball and the seed crystal is kept within the set range. The introduction of CH4, N2, and O2 is regularly turned off. During the off period, plasma etching is performed using H plasma. The microwave power used for etching is 9.5-10kw, the air pressure is 19-20KPa, and the etching time is 30 minutes. After the etching is completed, CH4, N2, and O2 are re-introduced to resume growth. Stable growth is obtained for 500-700 hours; Among them, the flow rates of CH4, N2, and O2 are 30sccm, 1sccm, and 1sccm respectively, and the N2 concentration is 10ppm.

2. The method for producing CVD single crystal diamond grown for a long time in one go as claimed in claim 1, characterized in that: The size of the CVD single crystal wafer selected in step (1) is 9 mm × 9 mm × 0.35 mm.

3. The method for producing CVD single crystal diamond grown for a long time in one go as claimed in claim 1, characterized in that: The cleaning step in step (2) is to soak the seed crystals in acetone, deionized water and alcohol in sequence, and then ultrasonically clean them. The soaking time in each cleaning medium is 30 minutes, and the ultrasonic cleaning time is 10 minutes.

4. The method for producing CVD single crystal diamond grown for a long time in one go as claimed in claim 1, characterized in that: The terraced structure molybdenum sample substrate stage used in step (3) is provided with concentric circular steps which are recessed from the outside to the inside and are arranged in a stepped distribution. Each step surface of the concentric circular steps is provided with a limiting convex ring extending upward. The limiting convex ring is used to separate the crystal seeds located on different step surfaces. Each step surface is also provided with a partition bar along the concentric circle diameter direction. The partition bar is used to separate the crystal seeds on the same step surface.

5. The method for producing CVD single crystal diamond grown for a long time in one go as claimed in claim 1, characterized in that: The purity of H2, N2, and O2 described in step (3) is greater than 99.999%, and the purity of CH4 is greater than 99.995%.

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