CN114086253B - Preparation method of electronic grade diamond - Google Patents

Preparation method of electronic grade diamond Download PDF

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Publication number
CN114086253B
CN114086253B CN202111409587.8A CN202111409587A CN114086253B CN 114086253 B CN114086253 B CN 114086253B CN 202111409587 A CN202111409587 A CN 202111409587A CN 114086253 B CN114086253 B CN 114086253B
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diamond
microwave plasma
growth
single crystal
assisted cvd
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CN114086253A (en
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彭国令
苗建国
曹光宇
冯文强
范旅龙
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Aerospace Science and Industry Changsha New Materials Research Institute Co Ltd
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Aerospace Science and Industry Changsha New Materials Research Institute 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
    • 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
    • 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
    • C23C16/02—Pretreatment of the material to be coated
    • C23C16/0227—Pretreatment of the material to be coated by cleaning or etching
    • C23C16/0245—Pretreatment of the material to be coated by cleaning or etching by etching with a plasma
    • 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
    • C23C16/22—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 deposition of inorganic material, other than metallic material
    • C23C16/26—Deposition of carbon only
    • C23C16/27—Diamond only
    • C23C16/274—Diamond only using microwave discharges
    • 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

Abstract

The invention provides a preparation method of electronic grade diamond, which comprises the following steps: performing microwave plasma etching treatment on the diamond seed crystal to obtain an etching pretreatment seed crystal; growing a single crystal diamond transition layer on the (100) surface of the etching pretreatment seed crystal by microwave plasma assisted CVD; and growing the electronic grade diamond on the surface of the single crystal diamond transition layer by microwave plasma assisted CVD. The method provided by the invention adopts a step-by-step growth mode, firstly grows a transition layer single crystal diamond with a certain thickness, the single crystal diamond transition layer can correct the defects of the diamond seed crystal substrate, then adopts microwave plasma assisted CVD to grow electronic grade diamond, and finally prepares the electronic grade single crystal diamond material with the impurity content lower than 2 ppm.

Description

Preparation method of electronic grade diamond
Technical Field
The invention relates to the technical field of diamonds, in particular to a preparation method of electronic grade diamonds.
Background
Diamond has been attracting attention as a third generation semiconductor material with its remarkable advantages of high thermal conductivity, high carrier mobility, wide forbidden bandwidth, and the like. However, high quality natural diamond has a limited reserves and is extremely expensive to develop, so various synthetic diamond methods have been developed, such as high temperature High Pressure (HPHT), hot wire chemical vapor deposition (HJCVD), microwave Plasma Chemical Vapor Deposition (MPCVD). Among them, the MPCVD method for synthesizing diamond is the most potential method for synthesizing diamond material of high quality and large area because of no introduction of impurities.
The quality of MPCVD diamond synthesis is dependent on a number of factors including carbon source concentration, gas flow, temperature, substrate table height, microwave power, synthesis temperature, plasma species and density distribution, temperature uniformity, etc. And the process parameters of the MPCVD method for synthesizing diamond are different from manufacturers and different types of equipment. It is known that a diamond film can be synthesized by controlling the concentration of a carbon source introduced and controlling appropriate process parameters such as temperature, pressure, power, etc., but in actual operation, such defects generally include point defects, line defects, surface defects, etc. due to the introduction of unavoidable impurity contamination sources, surface treatment defects, etc. The diamond grown by homoepitaxy has the same defects in the process of growing, and the defects such as NV defects, siV defects and the like have great influence on the electrical properties such as carrier mobility of the electronic grade diamond due to the introduction of impurity atoms in point defects. This has a great impact on the application of electronic grade diamond in detector devices, quantum measurement devices, quantum computing, etc.
A method for preparing electronic grade single crystal diamond by MPCVD method is proposed by IIA technologies company, which comprises: (a) selecting a diamond seed or substrate having a predetermined orientation, (b) cleaning and/or etching a non-diamond phase and other induced surface damage from said diamond seed or substrate, the step being performed a plurality of times, (c) growing a layer of extremely low crystal defect density diamond surface on the cleaned and/or etched diamond seed or substrate, the step being performed one or more times, and (d) growing electronic grade single crystal diamond on top of the extremely low crystal defect density diamond surface layer. However, in the method, when the step b is carried out, multiple times of etching are needed, and after the etching, single crystal diamond is needed to be taken out for observation and characterization, so that the state of low crystal defect density is ensured, and new impurities can be possibly introduced in the taking-out process, so that defects are generated in the synthesized electronic grade diamond material.
Disclosure of Invention
In view of the above, the present invention is directed to a method for preparing an electronic grade diamond single crystal, and finally preparing an electronic grade single crystal diamond with an impurity content of less than 2 ppm.
The invention provides a preparation method of electronic grade diamond, which comprises the following steps:
performing microwave plasma etching treatment on the diamond seed crystal to obtain an etching pretreatment seed crystal;
growing a single crystal diamond transition layer on the (100) surface of the etching pretreatment seed crystal by microwave plasma assisted CVD;
and growing the electronic grade diamond on the surface of the single crystal diamond transition layer by microwave plasma assisted CVD.
Preferably, the thickness of the single crystal diamond transition layer is 10 μm to 100 μm.
Preferably, the microwave plasma assisted CVD grown single crystal diamond transition layer comprises:
evacuating oxygen in the growth chamber, wherein the plasma in the growth chamber is H 2 Introducing carbon source gas into the growth cavity to perform microwave plasma assisted CVD to grow the single crystal diamond transition layer;
the carbon source gas and H 2 The volume concentration ratio of (2) is 0.1% -10%.
Preferably, the temperature of the single crystal diamond transition layer grown by microwave plasma assisted CVD is 850-1000 ℃, H 2 The gas flow rate is 100-1000 sccm, and the growth time is 30-90 min.
Preferably, the carbon source gas is methane or CO 2 Or methanol.
Preferably, the microwave plasma assisted CVD grown electronic grade diamond comprises:
after evacuating the growth chamber of the carbon source gas, at H 2 In the plasma atmosphere, simultaneously introducing carbon source gas and oxygen into the growth cavity to carry out microwave plasma assisted CVD to grow the electronic grade diamond;
the volume concentration ratio of the carbon source gas to the oxygen is 0.2-10%.
Preferably, the microwave plasma assisted CVD grows the carbon source gas and H of the electronic grade diamond 2 The volume concentration ratio of (2) to (12), H 2 Is of (1)The volume flow is 100-1000 sccm.
Preferably, the temperature of the microwave plasma assisted CVD for growing the electronic grade diamond is 850-1300 ℃, the growth pressure is 150-300 mbar, and the growth power is 2500-6000W.
Preferably, after the microwave plasma assisted CVD growth of the electronic grade diamond, the method further comprises: and cooling the growth system, wherein the cooling rate is 1-10 ℃/min.
Preferably, the microwave plasma etching is a microwave H 2 And (3) plasma etching, wherein the temperature of the microwave plasma etching is 850-950 ℃, and the time of the microwave plasma etching is 15-60 min.
The invention provides a preparation method of electronic grade diamond, which comprises the following steps: performing microwave plasma etching treatment on the diamond seed crystal to obtain an etching pretreatment seed crystal; growing a single crystal diamond transition layer on the (100) surface of the etching pretreatment seed crystal by microwave plasma assisted CVD; and growing the electronic grade diamond on the surface of the single crystal diamond transition layer by microwave plasma assisted CVD. The method provided by the invention adopts a step-by-step growth mode, firstly grows the transition layer single crystal diamond with a certain thickness, the single crystal diamond transition layer can correct the defects of the diamond seed crystal substrate, then adopts microwave plasma assisted CVD to grow the electronic grade diamond, finally prepares the electronic grade single crystal diamond material with the impurity content lower than 2ppm, and the impurity concentration of the sample of the whole electronic grade single crystal diamond is uniform and consistent and cannot change along with the change of depth.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 shows SIMS test results of an electronic grade diamond sample obtained in example 1 of the present invention.
Detailed Description
The invention provides a preparation method of electronic grade diamond, which comprises the following steps:
performing microwave plasma etching treatment on the diamond seed crystal to obtain an etching pretreatment seed crystal;
growing a single crystal diamond transition layer on the (100) surface of the etching pretreatment seed crystal by microwave plasma assisted CVD;
and growing the electronic grade diamond on the surface of the single crystal diamond transition layer by microwave plasma assisted CVD.
The invention carries out microwave plasma etching treatment on the diamond seed crystal to obtain the etching pretreatment seed crystal. The kind and source of the diamond seed crystal are not particularly limited in the present invention, and a seed crystal for growing diamond, which is well known to those skilled in the art, may be used. The present invention preferably carries out a cleaning treatment of the diamond seed crystal, the cleaning treatment preferably comprises polishing and cleaning, the polishing preferably comprises polishing the growth surface of the diamond seed crystal, the present invention preferably uses a (100) plane as the growth surface, the present invention has no special limitation on the polishing method, and the polishing technical scheme well known to the person skilled in the art can be adopted.
In the present invention, the cleaning preferably includes cleaning organics and cleaning metal impurities, and the cleaning organics are preferably: washing with acetone or absolute ethyl alcohol; the cleaning metal impurities are preferably acid-washed, and the acid-washed reagent is preferably a piranha solution.
After the cleaning treatment, the invention preferably carries out water washing and drying on the cleaned diamond seed crystal, and the water washing is preferably deionized water washing.
In the present invention, the microwave plasma etching is preferably H 2 The temperature of the microwave plasma etching is preferably 850-950 ℃, and in the embodiment of the invention, the temperature can be 850 ℃, 860 ℃, 870 ℃, 880 ℃, 890 ℃, 900 ℃, 910 ℃, 920 ℃, 930 ℃, 940 ℃ or 950 ℃; the time of the microwave plasma etching is preferably 15-60 min, and in the embodiment of the inventionThe medium may be 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min. In the present invention, oxygen is simultaneously introduced during the microwave plasma etching, and the percentage of oxygen and hydrogen is preferably 0.2-10%, and in the embodiment of the present invention, the percentage may be specifically 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%. In the present invention, the pressure of the microwave plasma etching is preferably 150mbar to 220mbar, and in the embodiment of the present invention, the pressure of the microwave plasma etching may be specifically 150mbar, 160mbar, 170mbar, 180mbar, 190mbar, 200mbar, 210mbar or 220mbar.
In the invention, the specific process of microwave plasma etching is preferably as follows: h is firstly introduced into the growth cavity 2 Introducing 300-1500W under 2-20 mabr pressure to generate microwave plasma, increasing pressure and power, and introducing O when the temperature of diamond seed crystal is stable at 850-950 DEG C 2 At this time, the etching is started for 15-60 min under the environment. In the present invention, the pressure increase rate is preferably 1 to 10mbar/min, and may be specifically 1mbar/min, 2mbar/min, 3mbar/min, 4mbar/min, 5mbar/min, 6mbar/min, 7mbar/min, 8mbar/min, 9mbar/min or 10mbar/min. In the present invention, the rate of increase of the power is preferably 10 to 300W/min, and may be specifically 10W/min, 20W/min, 50W/min, 70W/min, 90W/min, 110W/min, 130W/min, 150W/min, 170W/min, 190W/min, 210W/min, 230W/min, 250W/min, 270W/min, 280W/min or 300W/min. In the present invention, the power of the ignition is preferably 500 to 1500W, and may be specifically 500W, 600W, 700W, 800W, 900W, 1000W, 1100W, 1200W, 1300W, 1400W, or 1500W.
After the microwave plasma etching treatment, the invention grows the single crystal diamond transition layer on the (100) plane microwave plasma assisted CVD of the obtained etching pretreatment seed crystal. The invention preferably empties the oxygen in the growth chamber, the plasma in the growth chamber is H 2 Introducing carbon source gas into the growth cavity to perform microwave plasma assisted CVD to grow the single crystal diamond transition layer; the carbon source gas and H 2 Is of volume concentration of (1)The ratio is 0.1-10%. The method preferably stops introducing oxygen after the microwave plasma etching treatment, and stabilizes for a certain time to ensure oxygen evacuation; in the present invention, the stabilizing time is 5 to 30 minutes.
In the present invention, the carbon source gas is preferably methane or CO 2 Or methanol. In the present invention, the carbon source gas and H 2 The volume concentration ratio of (2) is preferably 0.1 to 10%, and may be specifically 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.
In the present invention, the temperature for growing the single crystal diamond transition layer by the microwave plasma assisted CVD is preferably 850 to 1000 ℃, and may be specifically 850 ℃, 860 ℃, 870 ℃, 880 ℃, 890 ℃, 900 ℃, 910 ℃, 920 ℃, 930 ℃, 940 ℃, 950 ℃, 960 ℃, 970 ℃, 980 ℃, 990 ℃, or 1000 ℃. In the invention, H is used when the microwave plasma assisted CVD grows the single crystal diamond transition layer 2 The gas flow rate of (2) is preferably 100 to 1000sccm, and may be specifically 100sccm, 150sccm, 200sccm, 250sccm, 300sccm, 350sccm, 400sccm, 450sccm, 500sccm, 550sccm, 600sccm, 650sccm, 700sccm, 750sccm, 800sccm, 850sccm, 900sccm, 950sccm or 1000sccm. In the invention, the growth time of the single crystal diamond transition layer grown by microwave plasma assisted CVD is preferably 30-90 min, and can be specifically 30min, 40min, 50min, 60min, 70min, 80min or 90min.
In the invention, the specific process of growing the single crystal diamond transition layer by microwave plasma assisted CVD is preferably as follows: stopping introducing O after the etching treatment is completed 2 Stabilize for a certain time to ensure that O 2 Completely discharging the cavity, and completely forming H-shaped microwave plasma 2 And (3) microwave plasma, wherein carbon source gas is introduced at the moment, and after the growth conditions are stabilized, the single crystal diamond transition layer starts to grow.
In the present invention, the growth thickness of the single crystal diamond transition layer is preferably between 10 and 100 μm, and may be specifically 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.
In the invention, in the growth process of the single crystal diamond transition layer, doping gas is preferably introduced into the cavity to obtain the doped single crystal diamond transition layer. In the present invention, the doping gas is preferably Ar gas and/or N 2 The method comprises the steps of carrying out a first treatment on the surface of the The volume ratio of the doping gas to the carbon source gas is preferably less than or equal to 2%, and the growth rate of the doped single crystal diamond transition layer is preferably less than or equal to 20um/h.
After growing to obtain the single crystal diamond transition layer, the invention grows the electronic grade diamond on the surface of the single crystal diamond transition layer by microwave plasma assisted CVD. In the present invention, the microwave plasma assisted CVD grown electronic grade diamond comprises: after evacuating the growth chamber of the carbon source gas, at H 2 In the plasma atmosphere, simultaneously introducing carbon source gas and oxygen into the growth cavity to carry out microwave plasma assisted CVD to grow the electronic grade diamond; the volume concentration ratio of the carbon source gas to the oxygen is 0.2-10%; the carbon source gas and H 2 The volume concentration ratio of (2) is preferably 2 to 12%. The method is preferable to stop introducing the carbon source gas after the growth of the single crystal diamond transition layer is finished, and the method is stable for a period of time to ensure that the carbon source gas is completely exhausted. In the present invention, the stabilizing time is preferably 5 to 30 minutes.
The invention simultaneously introduces carbon source gas and oxygen into the growth cavity. In the present invention, the carbon source gas is preferably methane or CO 2 Or methanol. The ratio of the volume concentration of the carbon source gas to the volume concentration of the oxygen gas is 0.2% to 10%, and may be specifically 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%. In the present invention, the carbon source gas and H 2 The volume concentration ratio of (2) to (12) may be specifically 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12%; h 2 The gas flow rate of (2) is 100-1000 sccm, and may be specifically 100sccm, 150sccm, 200sccm, 250sccm, 300sccm, 350sccm, 400sccm, 450sccm, 500sccm, 550sccm, 600sccm, 650sccm, 700sccm, 750sccm, 800sccm, 850sccm, 900sccm, 950sccm, or 1000sccm.
In the invention, in the preparation process of the electronic grade diamond, stable H 2 Preferably the flow rate of (c) remains unchanged.
In the present invention, the temperature of the microwave plasma assisted CVD grown electronic grade diamond is preferably 850 to 1300 ℃, and may be specifically 580 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, or 1300 ℃. In the present invention, the growth pressure of the microwave plasma assisted CVD grown electronic grade diamond is preferably 150 to 300mbar, and may be in particular 150mbar, 200mbar, 250mbar or 300mbar. In the present invention, the growth power of the microwave plasma assisted CVD grown electronic grade diamond is preferably 2500 to 6000W, and may be specifically 2500W, 3000W, 3500W, 4000W, 4500W, 5000W, 5500W or 6000W.
In the invention, the specific process of growing the electronic grade diamond by microwave plasma assisted CVD is preferably as follows: stopping the introduction of the carbon source after the growth of the single crystal diamond transition layer, stabilizing for a certain time to ensure that the carbon source is completely discharged out of the cavity, and then simultaneously introducing carbon source gas and O 2 And growing the electronic grade diamond.
In the present invention, the thickness of the grown electronic grade diamond is preferably 300 to 1500 μm.
After the electron-grade single crystal diamond is grown by microwave plasma assisted CVD, the invention preferably cools the growth system to obtain the electron-grade diamond. In the invention, the cooling rate is preferably 1-10 ℃/min. Preferably cooling to room temperature, and taking out the grown single crystal diamond product. In the invention, the cooling rate can be specifically 1 ℃/min, 2 ℃/min, 3 ℃/min, 4 ℃/min, 5 ℃/min, 6 ℃/min, 7 ℃/min, 8 ℃/min, 9 ℃/min or 10 ℃/min.
After the temperature is reduced, the electronic grade diamond obtained by growth is peeled off from the growth layer, and the electronic grade single crystal diamond is obtained. The method of the peeling is not particularly limited in the present invention, and in the embodiment of the present invention, the peeling preferably includes the steps of:
cutting the growth layer by laser;
mechanically polishing the growth layer;
and cleaning the mechanically polished growth layer.
In an embodiment of the present invention, the laser cutting may specifically be: and fixing the taken single crystal diamond sample on a tool of a laser cutting machine, adjusting the position of laser, and cutting and separating the growth layer.
In the present invention, the mechanical polishing is preferably performed until the roughness of the surface is 10nm or less. In the embodiment of the invention, the mechanical polishing can be specifically that the cut growth layer is placed on a clamp of a mechanical polishing device, gradually approaches to a grinding disc rotating at a high speed, the separation surface of the growth layer and the seed crystal layer and the growth layer of the diamond are polished, and the mechanical polishing is finished when the surface roughness after polishing reaches below 10 nm.
In the embodiment of the invention, the cleaning is to clean organic matters and metal impurities, and the growth layer after mechanical polishing can be placed in strong acid for cleaning to remove the organic matters and the metal impurities, so that the high-quality electronic grade diamond sample is finally obtained.
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
It should be noted that, without conflict, the following embodiments and features in the embodiments may be combined with each other; and, based on the embodiments in this disclosure, all other embodiments that may be made by one of ordinary skill in the art without inventive effort are within the scope of the present disclosure.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
Example 1
Selecting seed crystals with flat surfaces, wherein the sizes of the seed crystals are 4mm 1mm, the seed crystals are HPHT seed crystals, the growth surfaces are (100) surfaces, polishing the seed crystals, then placing absolute ethyl alcohol to wash away organic matters on the surfaces of the seed crystals, then using piranha solution to carry out pickling treatment, removing metal impurities on the surfaces of the seed crystals, washing away acid liquor by deionized water, and then placing the microwave plasma assisted CVD equipment cavity through drying treatment;
h is firstly introduced into the cavity before growth 2 ，H 2 The flow is 300sccm, and under the pressure of 10mabr, the power is introduced to 1500W for starting to generate plasma, then the pressure is increased at the speed of 9mbar/min, the power is increased at the speed of 120W/min, the pressure and the power are kept unchanged when the temperature of the seed crystal is stable at 860 ℃, and then the seed crystal is introduced to H 2 O3% by volume 2 Etching for 15 minutes in the environment;
after the etching treatment is completed, stopping introducing O 2 Stabilization for 5min ensures that O is taken up 2 Completely discharging the cavity, the plasma being completely H 2 And (3) plasma. At this time, let in with H 2 CH with a volume concentration ratio of 2% 4 Stabilizing the growth process parameters under the carbon source concentration: the temperature is controlled to be 930 ℃ plus or minus 5 ℃ and H 2 The gas flow of the diamond film is 300sccm, the stable gas flow and the carbon source concentration are unchanged, and the growth time is 60 minutes, so that a single crystal diamond transition layer is formed;
stopping CH after the growth of the transition layer is finished 4 Is introduced and stabilized for a certain period of time to ensure that CH is removed 4 Completely discharging the cavity. Then simultaneously introducing CH 4 And O 2 ，O 2 :CH 4 Concentration ratio of 1%, CH 4 :H 2 The ratio of the components is 6 percent, the growth temperature is 830+/-30 ℃, the growth pressure is 150-180 mbar, and the growth work is thatThe rate is controlled between 3000W and 4000W. And after the growth thickness is 1500 mu m, cooling, and gradually reducing the power and the gas pressure of the cavity to keep the cooling rate at 6 ℃/min. After the temperature is reduced to room temperature, taking out the grown monocrystalline diamond product;
and fixing the taken single crystal diamond product on a tool of a laser cutting machine, adjusting the position of laser, and cutting and separating the growth layer. And placing the growth layer on a clamp of a mechanical polishing device, gradually approaching to a grinding disc rotating at a high speed, polishing the separation surface of the growth layer and the seed crystal layer and the growth layer of the diamond, taking down a growth layer sample after polishing until the surface roughness reaches below 10nm, then placing the sample in strong acid for cleaning, and removing organic matters and metal impurities to finally obtain the high-quality electronic grade diamond sample.
The nitrogen impurity content of the sample obtained in this example was measured by the Secondary Ion Mass Spectrometry (SIMS) method and found to be 1.7X107 atom/cm 3 (about 1.01 ppm).
Example 2
Selecting seed crystals with flat surfaces, wherein the sizes of the seed crystals are 7mm x 0.5mm, the seed crystals are CVD seed crystals, the growth surfaces are (100) surfaces, polishing the seed crystals, then placing absolute ethyl alcohol to wash away organic matters on the seed crystal surfaces, then using piranha solution to carry out pickling treatment, removing metal impurities on the seed crystal surfaces, washing acid liquor by deionized water, and then placing the microwave plasma assisted CVD equipment cavity after drying treatment;
h is firstly introduced into the cavity before growth 2 ，H 2 The flow is 300sccm, and under the pressure of 10mabr, the power is introduced to 1500W for starting to generate plasma, then the pressure is increased at 7mbar/min, the power is increased at 100W/min, the pressure and the power are kept unchanged when the temperature of the seed crystal is stable at 880 ℃, and then the seed crystal is introduced to H 2 O3% by volume 2 Etching for 20 minutes in the environment;
after the etching treatment is completed, stopping introducing O 2 Stabilization for 5min ensures that O is taken up 2 Completely discharging the cavity, the plasma being completely H 2 And (3) plasma. At this time let inAnd H is 2 CH with a volume concentration ratio of 1% 4 . Stabilizing the growth process parameters under the carbon source concentration: the temperature is controlled to 900 ℃ +/-5 ℃ and H 2 The gas flow of the diamond film is 500sccm, the stable gas flow and the carbon source concentration are unchanged, and the growth time is 60 minutes, so that a single crystal diamond transition layer is formed;
stopping carbon CH after the growth of the transition layer is finished 4 After stabilizing for a certain period of time, ensure that the carbon source is completely discharged out of the cavity. Then let in CH 4 And O 2 ，O 2 :CH 4 Concentration ratio of 1%, CH 4 :H 2 The ratio of the materials is 8 percent, the growth temperature is 860+/-30 ℃, the growth pressure is 160 mbar-210 mbar, and the growth power is controlled to be 3000-4200W. After the growth thickness is 1300 μm, cooling is carried out, and the power and the gas pressure of the cavity are gradually reduced so as to keep the cooling rate at 8 ℃/min. After the temperature is reduced to room temperature, taking out the grown monocrystalline diamond product;
and fixing the taken single crystal diamond product on a tool of a laser cutting machine, adjusting the position of laser, and cutting and separating the growth layer. And placing the growth layer on a clamp of a mechanical polishing device, gradually approaching to a grinding disc rotating at a high speed, polishing the separation surface of the growth layer and the seed crystal layer and the growth layer of the diamond, taking down a growth layer sample after polishing until the surface roughness reaches below 10nm, then placing the sample in strong acid for cleaning, and removing organic matters and metal impurities to finally obtain the high-quality electronic grade diamond sample.
The nitrogen impurity content of the sample obtained in this example was measured by SIMS, and found to be 3.02X107 atom/cm 3 (about 1.72 ppm).
Example 3
Selecting a seed crystal with a flat surface, wherein the seed crystal is 6mm in size and 0.5mm in size, the seed crystal is of a CVD seed crystal type, the growth surface is a (100) surface, polishing the seed crystal, then placing absolute ethyl alcohol to wash away organic matters on the surface of the seed crystal, then using piranha solution to carry out pickling treatment, removing metal impurities on the surface of the seed crystal, washing away acid liquor by deionized water, and then placing the dried seed crystal into a cavity of microwave plasma-assisted CVD equipment;
h is firstly introduced into the cavity before growth 2 ，H 2 The flow is 100sccm, and under the pressure of 10mabr, the power is introduced to 1500W for starting to generate plasma, then the pressure is increased at the speed of 10mbar/min, the power is increased at the speed of 120W/min, the pressure and the power are kept unchanged when the temperature of the seed crystal is stable at 820 ℃, and then the seed crystal is introduced to H 2 O of 2% by volume 2 Etching for 30 minutes in the environment;
after the etching treatment is completed, stopping introducing O 2 Stabilization for 10 minutes ensures that O is taken up 2 Completely discharging the cavity, the plasma being completely H 2 And (3) plasma. At this time, let in with H 2 CH with a volume concentration ratio of 2% 4 . Stabilizing the growth process parameters under the carbon source concentration: the temperature is controlled to be 880+/-5 ℃ and H 2 The gas flow of the diamond film is 500sccm, the stable gas flow and the carbon source concentration are unchanged, and the growth time is 60 minutes, so that a single crystal diamond transition layer is formed;
stopping CH after the growth of the transition layer is finished 4 Is introduced and stabilized for a certain period of time to ensure that CH is removed 4 Completely discharging the cavity. Then let in CH 4 And O 2 ，O 2 :CH 4 Is 0.5%, CH 4 :H 2 The ratio of the materials is 5 percent, the growth temperature is 900+/-30 ℃, the growth pressure is 160 mbar-230 mbar, and the growth power is controlled to be 3000-4800W. After the growth thickness is 1300 μm, cooling is carried out, and the power and the gas pressure of the cavity are gradually reduced so as to keep the cooling rate at 8 ℃/min. After the temperature is reduced to room temperature, taking out the grown monocrystalline diamond product;
and fixing the taken single crystal diamond product on a tool of a laser cutting machine, adjusting the position of laser, and cutting and separating the growth layer. And placing the growth layer on a clamp of a mechanical polishing device, gradually approaching to a grinding disc rotating at a high speed, polishing the separation surface of the growth layer and the seed crystal layer and the growth layer of the diamond, taking down a growth layer sample after polishing until the surface roughness reaches below 10nm, then placing the sample in strong acid for cleaning, and removing organic matters and metal impurities to finally obtain the high-quality electronic grade diamond sample.
The nitrogen impurity content of the sample obtained in this example was measured by SIMS, and found to be 2.52X107 atom/cm 3 (about 1.43 ppm).
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (7)

1. The preparation method of the electronic grade diamond is characterized by comprising the following steps of:
performing microwave plasma etching treatment on the diamond seed crystal to obtain an etching pretreatment seed crystal; the specific process of microwave plasma etching is as follows: h is firstly introduced into the growth cavity 2 Introducing 300-1500W under 2-20 mabr pressure to generate microwave plasma, increasing pressure and power, and introducing O when the temperature of diamond seed crystal is stable at 850-950 DEG C 2 At the moment, starting timing and etching for 15-60 min under the environment; o (O) 2 And H 2 The percentage of (2) is 0.2-10%; the pressure of the microwave plasma etching is 150 mbar-220 mbar;
growing a single crystal diamond transition layer on the (100) surface of the etching pretreatment seed crystal by microwave plasma assisted CVD; the microwave plasma assisted CVD growth of single crystal diamond transition layer comprises: evacuating oxygen in the growth chamber, wherein the plasma in the growth chamber is H 2 Introducing carbon source gas into the growth cavity to perform microwave plasma assisted CVD to grow the single crystal diamond transition layer; the carbon source gas and H 2 The volume concentration ratio of (2) is 0.1% -10%;
growing electronic grade diamond on the surface of the single crystal diamond transition layer by microwave plasma assisted CVD; the microwave plasma assisted CVD growth of electronic grade diamond comprises: after evacuating the growth chamber of the carbon source gas, at H 2 In a plasma atmosphere, whileIntroducing carbon source gas and oxygen into the growth cavity to carry out microwave plasma assisted CVD to grow the electronic grade diamond; the volume concentration ratio of the carbon source gas to the oxygen is 0.2-10%; the carbon source gas and H 2 The volume concentration ratio of (2) to (12%).
2. The method of claim 1, wherein the single crystal diamond transition layer has a thickness of 10 μm to 100 μm.
3. The method according to claim 1, wherein the temperature for growing the single crystal diamond transition layer by microwave plasma assisted CVD is 850-1000 ℃, H 2 The gas flow rate is 100-1000 sccm, and the growth time is 30-90 min.
4. The method according to claim 1, wherein the carbon source gas is methane or CO 2 Or methanol.
5. The method of claim 1, wherein the microwave plasma assisted CVD grows an electron grade diamond carbon source gas and H 2 The volume concentration ratio of (2) to (12), H 2 The gas flow rate of (2) is 100-1000 sccm.
6. The method according to claim 1 or 5, wherein the temperature of the microwave plasma assisted CVD grown electronic grade diamond is 850-1300 ℃, the growth pressure is 150-300 mbar, and the growth power is 2500-6000W.
7. The method of claim 1, wherein the microwave plasma assisted CVD method further comprises: and cooling the growth system, wherein the cooling rate is 1-10 ℃/min.
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