CN115058770A - Method for manufacturing single crystal diamond for increasing growth quantity of CVD single crystal diamond - Google Patents

Method for manufacturing single crystal diamond for increasing growth quantity of CVD single crystal diamond Download PDF

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CN115058770A
CN115058770A CN202210747533.0A CN202210747533A CN115058770A CN 115058770 A CN115058770 A CN 115058770A CN 202210747533 A CN202210747533 A CN 202210747533A CN 115058770 A CN115058770 A CN 115058770A
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single crystal
growth
seed crystal
temperature
crystal diamond
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CN115058770B (en
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张国凯
陈明
曹通
李港雨
朱培
薛晨阳
郭鋆
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Zhongnan Diamond Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/18—Epitaxial-layer growth characterised by the substrate
    • C30B25/20—Epitaxial-layer growth characterised by the substrate the substrate being of the same materials as the epitaxial layer
    • C30B25/205—Epitaxial-layer growth characterised by the substrate the substrate being of the same materials as the epitaxial layer the substrate being of insulating material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/458—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for supporting substrates in the reaction chamber
    • C23C16/4582—Rigid and flat substrates, e.g. plates or discs
    • C23C16/4583—Rigid and flat substrates, e.g. plates or discs the substrate being supported substantially horizontally
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/12—Substrate holders or susceptors
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/16—Controlling or regulating
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/18—Epitaxial-layer growth characterised by the substrate
    • C30B25/186—Epitaxial-layer growth characterised by the substrate being specially pre-treated by, e.g. chemical or physical means
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/04—Diamond

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Abstract

The invention belongs to the technical field of single crystal diamond preparation processes, and particularly relates to a method for manufacturing single crystal diamonds for improving the growth quantity of CVD single crystal diamonds. Aiming at the defects in the prior art, the invention provides a method for manufacturing single crystal diamond for improving the growth quantity of CVD single crystal diamond, which improves the single growth quantity of the seed crystal and can ensure higher yield by controlling the contact between the plasma ball and the seed crystal, controlling the temperature difference between the central seed crystal and the edge seed crystal and simultaneously adding Ar to improve the concentration of the plasma ball. According to the method for manufacturing the single crystal diamond for improving the growth quantity of the CVD single crystal diamond, the growth process is controlled, the production efficiency is greatly improved, the problems that the single growth quantity of the CVD single crystal piece is small and the efficiency is low are solved, stable guarantee is provided for the industrial production of the single crystal diamond, and the method has a high development prospect and high economic value.

Description

Method for manufacturing single crystal diamond for increasing growth quantity of CVD single crystal diamond
Technical Field
The invention belongs to the technical field of single crystal diamond preparation processes, and particularly relates to a method for manufacturing single crystal diamonds for improving the growth quantity of CVD single crystal diamonds.
Background
Diamond is a special material with many excellent characteristics, and is widely applied to the fields of cutting tools, protective coatings, optical windows, acoustic sensors, semiconductors, electronic devices and the like. The single crystal diamond has excellent physical and chemical properties and good optical performance, and is widely applied to various fields of industry, science and technology, national defense, medical treatment and health care and the like. Natural diamond has low reserves and high price, and with the increase of the usage amount of the diamond, the problem of how to improve the yield of high-quality diamond material is urgently needed to be solved.
Chemical Vapor Deposition (CVD) is currently the dominant method for synthesizing large-sized single crystal diamond. Conventionally, the size of a diamond single crystal synthesized by the CVD method depends on the size of a seed crystal, and generally, the size of the synthesized single crystal is equal to or smaller than that of the seed crystal. Therefore, there is a need for an improved technique for manufacturing a large-sized diamond single crystal. Among the CVD methods, MPCVD (microwave plasma chemical vapor deposition), which is the most suitable method for growing single crystal diamond, has the advantages of high synthesis efficiency, high plasma density, stable temperature field, etc., and the prepared single crystal diamond has good uniformity and high quality.
In the prior art, the equipment for synthesizing the CVD single-crystal diamond by adopting the MPCVD method often has the problems of uneven plasma distribution, uneven cooling of a water-cooling heat dissipation base station, different contact between a seed crystal and a sample station and the like, so that the growth state difference of the seed crystal is large, and the quality of the single-crystal diamond grown at one time is different.
Chinese patent publication No. CN108251892A discloses an apparatus and method for preparing single crystal diamond by laser enhanced plasma CVD, the apparatus includes a plasma CVD device and a laser device; the number of the laser devices is more than 1, the laser devices are respectively positioned at the outer side of the cylindrical cavity of the plasma CVD device, the method utilizes low-cost high-energy laser to improve the energy and gas dissociation rate of plasma in the diamond synthesis process, and therefore the synthesis rate of the diamond is improved.
In the growth process of the MPCVD single crystal diamond, the improvement of the single growth quantity and the yield can greatly improve the production efficiency and shorten the preparation period of the seed crystal, thereby being the basis and guarantee for realizing the industrial production of the single crystal diamond. Based on the method, the growth speed and the number of single seed crystals are changed by contacting the plasma ball on the MPCVD equipment with the seed crystals and adding Ar, so as to improve the synthesis efficiency of the CVD single crystal diamond.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for manufacturing single crystal diamond for improving the growth quantity of CVD single crystal diamond, which improves the single growth quantity of the seed crystal and can ensure higher yield by controlling the contact between the plasma ball and the seed crystal, controlling the temperature difference between the central seed crystal and the edge seed crystal and simultaneously adding Ar to improve the concentration of the plasma ball.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
a method of producing single crystal diamond for increasing the amount of CVD single crystal diamond growth, comprising the steps of:
(1) seed crystal screening:
25-27 CVD single crystal wafers with the crystallographic orientation of (100) are used as seed crystals, and the surface is required to be free of defects and the edge quality is required to be good;
(2) pretreatment of seed crystals:
soaking the seed crystal in an organic solvent, and then cleaning;
(3) single wafer growth using MPCVD equipment:
a. putting the seed crystal in the step (2) into a molybdenum sample base station, putting the seed crystal on an MPCVD device, and vacuumizing to 1 x 10 - 3 Pa or less, then simultaneously introducing H 2 、N 2 Ar, forming a plasma ball in the MPCVD equipment and contacting with the seed crystal to promote the growth of the seed crystal, setting the microwave power at 2-3kw and the air pressure at 100-120mbar, keeping the temperature at 700-800 ℃, keeping for 1-2h, aiming at reducing the difference of the growth states of the center and edge seed crystals and ensuring the stability of energy required by the growth of the seed crystal by keeping for a long time at a moderate temperature;
b. adjusting the microwave power to 2.5-3.5kw and the air pressure to 120-140mbar, wherein the temperature gradually rises due to the rise of the microwave power and the air pressure, and CH is introduced when the temperature reaches 850-900 DEG C 4 Keeping the temperature for 10-15min, adjusting the microwave power to 2.8-3.8kw, adjusting the air pressure to 140-160mbar, and keeping the temperature at 1000-1050 ℃ for stable growth for 40-45 h;
in the step, the volume of a plasma ball is increased, the coverage area of a sample table is increased and the uniformity of a temperature field in a cavity is ensured mainly through the matching of high microwave power and low air pressure; by a higher proportion of CH 4 The growth speed of the (100) crystal direction is promoted, and the microwave power and the gas pressure are properly adjusted to keep stable growth.
Preferably, the dimensions of the CVD single crystal wafer selected in step (1) are 8mm by 0.3 mm.
Preferably, the cleaning step in the step (2) is to sequentially place the seed crystal in acetone and alcohol for soaking, and then ultrasonically clean, wherein the soaking time in each cleaning medium is 20-30min, and the ultrasonically cleaning time is 2-3 min.
Preferably, in the step (3), the molybdenum sample base station has a combined structure of an upper layer and a lower layer, the upper layer is a wafer with the size phi of 60mm multiplied by 10mm, the lower layer is a molybdenum support with the size phi of 50mm multiplied by 5mm and a bottom convex structure, the seed crystal is placed between the upper layer and the lower layer of the molybdenum sample base station, and the placing distance between every two adjacent seed crystals is 0.5-1 mm.
Preferably, step (3) is performed by H 2 、N 2 The flow rates of Ar are 900-1000sccm and 2-3sccm respectivelym、10-20sccm，N 2 The concentration is 20-35 ppm.
Preferably, H is introduced in step (3) 2 、N 2 And after Ar, adjusting an E-H tuner (which can change the shape of a plasma cluster while ensuring that the maximum transmission power enters a plasma source by adjusting microwave impedance matching) on the MPCVD equipment to enable the plasma sphere to be in a partial ellipsoid shape, and adjusting the temperature difference between the center and the edge of the seed crystal not to exceed 80 ℃.
Preferably, in step (3), CH 4 The flow rate of (a) is 80-90 sccm.
Preferably, CH is closed at an interval of 12-18h during the growth process 4 、N 2 During the closing period, H plasma is used for plasma etching, the microwave power used for etching is 3.5-3.8kw, the air pressure is 140-150mbar, the etching time is about 1-2min, CH is introduced again after the etching is finished 4 、N 2 The growth is recovered, the microwave power and the air pressure are adjusted in the etching process, the temperature fluctuation is kept to be not more than 30 ℃, the adoption of the interval etching mode is favorable for purifying the growth environment in the reaction cavity, the growth surface quality is improved, and the growth time is obviously promoted.
Specifically, H in the step (4) 2 、N 2 Has a purity of more than 99.999 percent and CH 4 Has a purity of more than 99.995%.
Further, the invention also provides CVD single crystal diamond prepared by the method.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention provides a device for increasing the growth quantity of CVD single crystal diamonds and a manufacturing method of the single crystal diamonds, wherein a uniquely designed molybdenum sample base platform structure is adopted, the heat dissipation performance is good, the energy of a plasma ball is increased by adding Ar, the volume of the plasma ball and the coverage area of seed crystals are controlled, the uniformity of a temperature field of a reaction cavity is improved, the single growth quantity of the single crystal diamonds is greatly increased by matching with proper technological parameters, and the high yield is ensured.
2. According to the method for manufacturing the single crystal diamond for improving the growth quantity of the CVD single crystal diamond, the growth process is controlled, the production efficiency is greatly improved, the problems that the single growth quantity of the CVD single crystal piece is small and the efficiency is low are solved, stable guarantee is provided for the industrial production of the single crystal diamond, and the method has a high development prospect and high economic value.
Drawings
FIG. 1 is a photograph of a single crystal diamond in a grown state in step (3) of example 1;
FIG. 2 is a schematic view of a molybdenum sample stage;
FIG. 3 is a photograph of a single crystal diamond after the growth of example 1 was completed;
FIG. 4 is a photograph of a single crystal diamond on a molybdenum sample base station after the growth of example 1, the size being 60 mm;
FIG. 5 is a photograph of a single crystal diamond in a grown state in step (3) of comparative example 1;
fig. 6 is a photograph of a single crystal diamond obtained after the growth of comparative example 1 was completed.
Detailed Description
In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The MPCVD equipment used in the embodiment of the invention is a CYRANNUS system in Germany, and the working parameter is 6kw-2.45 GHz.
Example 1
A manufacturing method of single crystal diamond for increasing the growing quantity of CVD single crystal diamond specifically comprises the following steps:
(1) seed crystal screening:
using 27 pieces of CVD single crystal wafer with the size of about 8mm × 8mm × 0.3mm, the crystallographic orientation of (100), and the surface polishing (to nano-scale roughness) as seed crystal, it is required that the surface is free of defects and the edge quality is good;
(2) pretreatment of seed crystals:
soaking the seed crystal in acetone and alcohol for 20min, and ultrasonically cleaning in alcohol for 3 min;
(3) growing a single crystal wafer:
a. selecting one surface with good edge quality and no visible defects as a growth surface, uniformly placing the surface into a molybdenum sample base station (as shown in figure 2), wherein the molybdenum sample base station is of an upper-lower double-layer combined structure, the upper layer is a wafer with the size of phi 60mm multiplied by 10mm, the lower layer is a molybdenum support with the size of phi 50mm multiplied by 5mm and a bottom convex structure, placing crystal seeds between the upper layer and the lower layer of the molybdenum sample base station, the placing distance between two adjacent crystal seeds is about 1mm, placing the crystal seeds on an MPCVD device, opening the MPCVD device, and vacuumizing to 1 multiplied by 10 -3 Then simultaneously introducing H 2 、N 2 Ar, the flow rate is 1000sccm, 3sccm, 15sccm, N 2 Forming plasma spheres in an MPCVD device at a concentration of 20ppm, contacting with the seed crystal to promote the growth of the seed crystal, and setting the microwave power at 3kw and the air pressure at 110 mbar; adjusting an E-H tuner (which can change the form of a plasma cluster while ensuring that the maximum transmission power enters a plasma source by adjusting microwave impedance matching) on the MPCVD equipment to enable a plasma sphere to be in a partial ellipsoid shape, keeping the temperature at 700-800 ℃ and keeping the temperature for 1H;
b. adjusting the microwave power to 3.5kw and the air pressure to 130mbar, wherein the temperature gradually rises due to the rise of the microwave power and the air pressure, and CH is introduced when the temperature reaches 850-900 DEG C 4 The flow rate is 90sccm, the temperature is kept for 15min, the microwave power is adjusted to be 3.5-3.8kw, the air pressure is adjusted to be 150-; the growth state photo of the single crystal diamond is shown in figure 1, and as can be seen from figure 1, the integral temperature field of the single crystal wafer is relatively uniform in the growth process, and the growth state consistency is relatively good;
in the growth process, CH is closed at an interval of 12h 4 、N 2 Performing plasma etching on the growth surface, the edge polycrystal and the inner wall of the reaction cavity by using H plasma during closing, wherein the microwave power used for etching is 3.5-3.8kw, the air pressure is 140-150mbar, the etching time is about 2min, and introducing CH again after the etching is finished 4 、N 2 Restoring growth, regulating microwave power and air pressure during etching process, maintaining temperature fluctuation not more than 30 deg.C, and facilitating purification of the inner part of the reaction chamber by adopting interval etching modeThe growth environment of the growth furnace improves the quality of the growth surface and obviously promotes the growth time.
H described in step (3) 2 、N 2 Has a purity of more than 99.999% and CH 4 Has a purity of more than 99.995%.
The method of this embodiment achieves the improvement of the single growth quantity of the seed crystal by controlling the contact between the plasma ball and the seed crystal, controlling the temperature difference between the center seed crystal and the edge seed crystal, and simultaneously adding Ar to improve the concentration of the plasma ball, and the obtained results are shown in fig. 3 and fig. 4, fig. 3 is a photo of the single crystal diamond obtained after the growth is finished, and fig. 4 is a photo of the single crystal diamond on the molybdenum sample base station after the growth is finished.
In the prior art, a common CVD method is adopted to grow the single crystal diamond, the size of a sample table in common MPCVD equipment is basically phi 50mm, and due to the limitation of the equipment, the forced increase of the size of a plasma sphere has the risk of system collapse, so that the quartz window is easily ablated to cause equipment damage, and the single growth quantity cannot be further increased.
Compared with the prior art, the invention has the advantages that on the premise of ensuring safety, the molybdenum sample base station with the upper and lower double-layer combined structure is adopted, the plasma ball is extruded to be adsorbed to the surface of the sample station, meanwhile, certain Ar is added to improve the plasma strength, the molybdenum sample base station structure is specially designed, the good heat dissipation performance is realized, the uniform and stable temperature field of the CVD single crystal growth surface is achieved, and the growth efficiency is further improved on the basis of ensuring that the yield is not lower than 80%.
As can be seen from FIG. 3, except that the individual single crystals are yellow, the colors of the other single crystals are better, the crystallization quality is good, and the yield is higher.
Example 2
A method for manufacturing single crystal diamond for increasing the growth amount of CVD single crystal diamond, comprising the steps of:
(1) seed crystal screening:
using 27 pieces of CVD single crystal wafer with the size of about 8mm × 8mm × 0.3mm, the crystallographic orientation of (100), and the surface polishing (to nano-scale roughness) as seed crystal, it is required that the surface is free of defects and the edge quality is good;
(2) pretreatment of seed crystals:
soaking the seed crystal in acetone and alcohol for 30min, and ultrasonically cleaning in alcohol for 2 min;
(3) growing a single crystal wafer:
a. selecting one surface with good edge quality and no visible defects on the surface as a growth surface, uniformly placing the surface into a molybdenum sample base station, wherein the molybdenum sample base station has an upper-lower double-layer combined structure, the upper layer is a phi 60mm multiplied by 10mm wafer, the lower layer is a phi 50mm multiplied by 5mm molybdenum support with a bottom convex structure, placing crystal seeds between the upper layer and the lower layer of the molybdenum sample base station, placing two adjacent crystal seeds with a spacing of about 0.5mm, placing the crystal seeds on an MPCVD device, opening the MPCVD device, and vacuumizing to 1 multiplied by 10 -3 Pa or less, then simultaneously introducing H 2 、N 2 Ar with a flow rate of 900sccm, 2.5sccm, 10sccm, N 2 Forming plasma balls in the MPCVD equipment at a concentration of 30ppm and contacting with the seed crystal to promote the growth of the seed crystal, and setting the microwave power at 2.5kw and the gas pressure at 100 mbar; adjusting an E-H tuner (which can change the form of a plasma cluster while ensuring that the maximum transmission power enters a plasma source by adjusting microwave impedance matching) on the MPCVD equipment to enable a plasma sphere to be in a partial ellipsoid shape, keeping the temperature at 700-750 ℃ and keeping the temperature for 1.5H;
b. adjusting the microwave power to 3.5kw and the air pressure to 120mbar, wherein the temperature gradually rises due to the rise of the microwave power and the air pressure, and CH is introduced when the temperature reaches 850-900 DEG C 4 The flow rate is 80sccm, the temperature is kept for 10min, the microwave power is adjusted to be 3.3-3.7kw, the air pressure is adjusted to be 145-155mbar, and the temperature is kept between 1000 ℃ and 1050 ℃ for stable growth for 45 h;
in the growth process, the CH is closed at an interval of 12h 4 、N 2 Performing plasma etching on the growth surface, the edge polycrystal and the inner wall of the reaction chamber by using H plasma during closing, wherein the microwave power used for etching is 3.6-3.8kw, the air pressure is 145-150mbar, the etching time is about 2min, and introducing CH again after the etching is finished 4 、N 2 Recovering growth, regulating microwave power and gas pressure during etching process, and keeping temperature fluctuation not more than 3The adoption of the interval etching mode at 0 ℃ is beneficial to purifying the growth environment in the reaction cavity, improving the growth surface quality and playing a role in obviously promoting the growth time.
H described in the step (3) 2 、N 2 Has a purity of more than 99.999% and CH 4 Has a purity of more than 99.995%.
The method of the embodiment controls the contact between the plasma ball and the seed crystal, controls the temperature difference between the central seed crystal and the edge seed crystal, and simultaneously adds Ar to improve the concentration of the plasma ball, thereby realizing the improvement of the single growth quantity of the seed crystal and simultaneously ensuring that the yield is not lower than 80%.
Comparative example 1
Comparative example 1 a conventional CVD single crystal diamond manufacturing method was improved and compared with examples 1, 2, specifically including the steps of:
(1) seed crystal screening:
using 27 pieces of CVD single crystal wafer with the size of about 8mm × 8mm × 0.3mm, the crystallographic orientation of (100), and the surface polishing (to nano-scale roughness) as seed crystal, it is required that the surface is free of defects and the edge quality is good;
(2) pretreatment of seed crystals:
soaking the seed crystal in acetone and alcohol for 20min, and ultrasonically cleaning in alcohol for 3 min;
(3) growing a single crystal wafer:
a. selecting one surface with good edge quality and no visible defects on the surface as a growth surface, uniformly placing the surface in a molybdenum sample base station which is of an upper and lower double-layer combined structure, wherein the upper layer is a wafer with the size of phi 60mm multiplied by 10mm, the lower layer is a molybdenum holder with the size of phi 60mm multiplied by 5mm, placing crystal seeds between the upper and lower double layers of the molybdenum sample base station, placing the adjacent two crystal seeds with the space of about 0.5mm, placing the crystal seeds on an MPCVD device, opening the MPCVD device, and vacuumizing to 1 multiplied by 10 -3 Pa below, then simultaneously introducing H 2 、N 2 The flow rates are respectively 1000sccm, 2.5sccm and N 2 The concentration is 30ppm, the microwave power is 3kw, and the air pressure is 140 mbar; properly adjusting the height of a sample table, keeping the temperature at 700-750 ℃, and keeping for 1.5 h;
b. regulating the microwaveThe power is 3.5kw, the air pressure is 160mbar, the temperature rises gradually due to the rise of the microwave power and the air pressure, and CH is introduced when the temperature reaches 850-900 DEG C 4 The flow rate is 90sccm, the temperature is kept for 10min, the microwave power is adjusted to be 3.4-3.9kw, the air pressure is 170-;
in the growth process, the CH is closed at an interval of 12h 4 、N 2 Performing plasma etching on the growth surface, the edge polycrystal and the inner wall of the reaction chamber by using H plasma during closing, wherein the microwave power used for etching is 3.6-3.9kw, the air pressure is 180-190mbar, the etching time is about 3min, and introducing CH again after the etching is finished 4 、N 2 Restoring growth, regulating microwave power and air pressure in the etching process, and keeping the temperature fluctuation not more than 30 ℃.
H described in step (3) 2 、N 2 Has a purity of more than 99.999 percent and CH 4 Has a purity of more than 99.995%.
In comparative example 1, the molybdenum sample stage having a heat dissipation function was not used, the state of the plasma bulb was not changed by the depth of the E-H conditioner, and the strength of the plasma bulb was not increased by using Ar, so that it was necessary to use higher power and pressure to increase the plasma activity, and further increase of pressure resulted in increase of temperature of the single wafer at the center and edge of the sample stage, which was not favorable for ensuring the stability of the growth state. Comparative example 1 the growth state of the single crystal diamond in step (3) is shown in fig. 5, and the obtained results are shown in fig. 6.
As can be seen from fig. 5, the temperature difference between the center and the edge cannot be ensured during the growth process, the center is easily overheated due to the too high plasma sphere strength, and the edge is insufficient in energy due to the too low temperature. As can be seen from FIG. 6, the single crystal in the central region has a good color, but is prone to generate high-temperature polycrystalline defects, and the single crystal in the edge region has a brownish yellow color, and is prone to form serious penetrating impurities and cracks.
While specific embodiments of the present invention have been described above, it should be understood that the present invention is not limited to the specific embodiments described above. Various changes or modifications within the scope of the appended claims may be made by those skilled in the art without departing from the true spirit of the invention.

Claims (10)

1. A method of producing single crystal diamond for increasing the number of CVD single crystal diamond growths comprising the steps of:
(1) seed crystal screening:
using a CVD single crystal wafer having a crystallographic orientation of (100) as a seed crystal, it is required to have a defect-free surface;
(2) pretreatment of seed crystals:
soaking the seed crystal in an organic solvent, and then cleaning;
(3) single wafer growth using MPCVD equipment:
a. putting the seed crystal in the step (2) into a molybdenum sample base station, putting the seed crystal on an MPCVD device, and vacuumizing to 1 x 10 -3 Pa or less, then simultaneously introducing H 2 、N 2 Ar, forming a plasma ball in the MPCVD equipment and contacting with the seed crystal to promote the growth of the seed crystal, setting the microwave power at 2-3kw and the air pressure at 100-120mbar, keeping the temperature at 700-800 ℃, and keeping the temperature for 1-2 h;
b. adjusting the microwave power to 2.5-3.5kw and the air pressure to 120-140mbar, wherein the temperature gradually rises due to the rise of the microwave power and the air pressure, and CH is introduced when the temperature reaches 850-900 DEG C 4 Keeping the temperature for 10-15min, adjusting the microwave power to 2.8-3.8kw, adjusting the air pressure to 140-160mbar, and keeping the temperature at 1000-1050 ℃ for stable growth for 40-45 h.
2. The method of claim 1 wherein the CVD single crystal wafer size selected in step (1) is 8mm x 0.3 mm.
3. The production method according to claim 1, wherein the cleaning step in the step (2) is a step of immersing the seed crystal in acetone and alcohol in this order, followed by ultrasonic cleaning, and the immersion time in each cleaning medium is 20 to 30min, and the ultrasonic cleaning time is 2 to 3 min.
4. The manufacturing method according to claim 1, wherein in the step (3), the molybdenum sample base has an upper and lower double-layer combined structure, the seed crystal is placed between the upper and lower double layers of the molybdenum sample base, and the placement distance between two adjacent seed crystals is 0.5-1 mm.
5. The method of claim 1, wherein H in step (3) 2 、N 2 The flow rate of Ar is 900-1000sccm, 2-3sccm, 10-20sccm, N 2 The concentration is 20-35 ppm.
6. The method of claim 1, wherein H is introduced in step (3) 2 、N 2 After Ar, adjusting an E-H tuner on the MPCVD equipment, and adjusting the temperature difference between the center and the edge of the seed crystal not to exceed 80 ℃.
7. The method of claim 1, wherein in step (3), CH 4 The flow rate of (a) is 80-90 sccm.
8. The method of claim 1, wherein the CH is turned off at intervals of 12-18h during the growth process 4 、N 2 During the closing period, H plasma is used for plasma etching, the microwave power used for etching is 3.5-3.8kw, the air pressure is 140-150mbar, the etching time is 1-2min, CH is introduced again after the etching is finished 4 、N 2 Restoring growth, regulating microwave power and air pressure in the etching process, and keeping the temperature fluctuation not more than 30 ℃.
9. The method of claim 1, wherein the H in step (4) 2 、N 2 Has a purity of more than 99.999% and CH 4 Has a purity of more than 99.995%.
10. A CVD single crystal diamond produced by the method of any one of claims 1 to 9.
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