CN112941487A - Polycrystalline diamond thick film for microwave energy transmission window and preparation method thereof - Google Patents

Polycrystalline diamond thick film for microwave energy transmission window and preparation method thereof Download PDF

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CN112941487A
CN112941487A CN202110171912.5A CN202110171912A CN112941487A CN 112941487 A CN112941487 A CN 112941487A CN 202110171912 A CN202110171912 A CN 202110171912A CN 112941487 A CN112941487 A CN 112941487A
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diamond
film
diamond film
thick film
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CN112941487B (en
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李义锋
安晓明
姜龙
张雅淋
刘晓晨
葛新岗
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Hebei Plasma Diamond Technology Co ltd
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Hebei Plasma Diamond Technology Co ltd
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    • 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
    • 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
    • C23C16/50—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 using electric discharges
    • C23C16/511—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 using electric discharges using microwave discharges
    • 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
    • C23C16/52—Controlling or regulating the coating process

Abstract

The polycrystalline diamond thick film for the microwave energy transmission window is of a double-layer columnar crystal structure and comprises a first layer of diamond film and a second layer of diamond film, wherein the second layer of diamond film grows on the nucleation surface of the first layer of diamond film, and the growing surfaces of the first layer of diamond film and the second layer of diamond film are positioned at two ends. The method adopts a step-by-step deposition method to prepare the double-layer columnar crystal structure with the nucleation surface positioned inside the multilayer diamond thick film and the growth surface positioned on the surfaces of two ends, and the prepared polycrystalline diamond thick film has the characteristics of high strength, low dielectric loss, less internal defects and high bending strength of the growth surface, and the preparation method has high deposition efficiency.

Description

Polycrystalline diamond thick film for microwave energy transmission window and preparation method thereof
Technical Field
The invention relates to a polycrystalline diamond thick film, in particular to a polycrystalline diamond thick film for a microwave energy transmission window and a preparation method thereof.
Background
Along with the improvement of parameters of the nuclear fusion device, the frequency of the gyrotron for microwave heating reaches more than hundred gigahertz, the output power reaches more than megawatt level, the pulse width reaches thousands of seconds level, and the gyrotron has the characteristics of high efficiency, high reliability and the like. Under such harsh working conditions, the gyrotron microwave energy transmission window material must simultaneously satisfy the performances of small dielectric constant, low high-frequency loss, high thermal conductivity, high mechanical strength and the like. Conventional Al2O3Materials such as BeO, boron nitride and the like can not meet the requirements, and the diamond becomes the only optional window material for the microwave energy transmission window of the megawatt gyrotron due to the excellent comprehensive performance of the diamond.
Diamond is used as a high-power microwave energy transmission window material, the thickness of the diamond is generally required to be more than 1-2mm, and the dielectric loss needs to meet the requirement that tan delta is less than or equal to 5 multiplied by 10-5The bending strength is more than or equal to 200 Mpa. However, the deposition efficiency of the conventional chemical vapor deposition method, especially the microwave plasma chemical vapor deposition method, is low, and the deposition rate is generally less than 2 μm/h. For preparing high-quality diamond thick films with the thickness of 1-2mm, the deposition time must reach thousands of hours. The single long-time deposition of the diamond thick film brings two problems, on one hand, the stability of a deposition system is tested due to thousands of hours of continuous operation, and the deposition system possibly breaks down; on the other hand, in the polycrystalline diamond film synthesis process, unlike single crystals, fine crack-like features are easily formed at grain boundaries or inside crystal grains, called "black defects", which have various shapes and sizes and are in a tendency to deteriorate with growth time and thickness. Since the black defect can seriously affect the dielectric loss and the service performance of the diamond film, the adjustment and control of the size and the density of the black defect inside the diamond film are necessary to be realized by controlling the time and the thickness of single growth of the diamond film.
In addition, the time and thickness of a single growth of the diamond film also affect the strength of the diamond film. In the long-time growth process of the diamond film, diamond grains grow gradually and generate preferred orientation, and a conical columnar crystal structure with small grain size of a nucleation surface and large grain size of a growth surface is presented. This growth mode and structure also presents two problems: on one hand, according to the fine grain strengthening principle, the strength of a nucleation surface with small grain size and more grain boundaries is far greater than that of a diamond growth surface with large grain size and less grain boundaries; on the other hand, as the thickness of the diamond film increases, the grain size of the growth surface grows larger, the grain boundary gradually decreases, and the bending strength of the growth surface also gradually decreases. Therefore, to increase the bending strength of the growth surface of the diamond film, the time and thickness of the single growth of the diamond film are controlled, so as to control the degree of preferred orientation of the crystal grains and the degree of growth of the crystal grains.
In summary, due to the limitations of the deposition method, synthesis equipment and crystal growth characteristics, the high-strength low-loss diamond thick film window material for the high-power microwave energy transmission window is not easy to prepare at present, and the existing single growth process has many problems, including low growth efficiency, many internal defects, high dielectric loss, low bending strength of the growth surface and the like.
Disclosure of Invention
The invention provides a polycrystalline diamond thick film for a microwave energy transmission window and a preparation method thereof, aiming at overcoming the defects of the prior art, the polycrystalline diamond thick film for the microwave energy transmission window is prepared by adopting a step-by-step deposition method, a double-layer columnar crystal structure with a nucleation surface positioned in the multilayer diamond thick film and a growth surface positioned on the surfaces of two ends is prepared, the prepared polycrystalline diamond thick film has the characteristics of high strength, low dielectric loss, less internal defects and high bending strength of the growth surface, and the preparation method has high deposition efficiency.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the polycrystalline diamond thick film for the microwave energy transmission window is of a double-layer columnar crystal structure and comprises a first layer of diamond film and a second layer of diamond film, wherein the second layer of diamond film grows on the nucleation surface of the first layer of diamond film, and the growing surfaces of the first layer of diamond film and the second layer of diamond film are positioned at two ends.
A preparation method of a polycrystalline diamond thick film for a microwave energy transmission window is disclosed, wherein the thick film is prepared by a step growth method and comprises the following steps:
a. depositing a first layer of diamond film with a preset thickness on the surface of a substrate in a plasma atmosphere by adopting a chemical vapor deposition method, wherein the contact end of the first layer of diamond film and the substrate is a nucleation surface, and the end deviating from the substrate is a growth surface;
b. separating the first layer of diamond film from the substrate, processing the nucleation surface of the first layer of diamond film, and brazing the growth surface of the processed first layer of diamond film to the substrate;
c. placing the first layer of diamond film and the substrate which are brazed together into chemical vapor deposition equipment, and continuously growing a second layer of diamond film on the nucleation surface of the first layer of diamond film to a preset thickness;
d. and separating the substrate to obtain the high-strength low-loss polycrystalline diamond thick film.
According to the preparation method of the polycrystalline diamond thick film for the microwave energy transmission window, the plasma atmosphere comprises hydrogen and methane.
According to the preparation method of the polycrystalline diamond thick film for the microwave energy transmission window, the plasma atmosphere further comprises one or more of oxygen, argon and nitrogen.
According to the preparation method of the polycrystalline diamond thick film for the microwave energy transmission window, the substrate material adopted by growth and brazing is one of silicon, molybdenum, tungsten or graphite. The substrate has the requirements of high melting point, easy formation of carbide on the surface and expansion coefficient close to that of diamond.
The preparation method of the polycrystalline diamond thick film for the microwave energy transmission window is characterized in that the chemical vapor deposition method is a microwave plasma chemical vapor deposition method, the deposition growth conditions of the first layer of diamond film and the second layer of diamond film are the same, the average deposition growth rate is 0.5-15 mu m/h, the deposition temperature is 700-fold ion flow 1100 ℃, the methane concentration is 1-10%, the hydrogen flow is 50-5000sccm, the microwave input frequency is 2.45GHz or 915MHz, and the microwave input power is 5-75 kW.
According to the preparation method of the polycrystalline diamond thick film for the microwave energy transmission window, the growth thicknesses of the first layer of diamond film and the second layer of diamond film are both 0.1-2.5 mm. The growth thickness of the first layer of diamond film and the second layer of diamond film is deposited according to the quality and application requirements.
In the step b, the processing of the nucleation surface of the first layer of diamond film is grinding, polishing or plasma etching.
In the above method for preparing the polycrystalline diamond thick film for the microwave energy transmission window, in the steps b and c, under the condition that the temperature uniformity and controllability of the diamond film can be ensured, the first layer of diamond can be connected with the substrate in other modes, or the second layer of diamond film can be directly grown on the nucleation surface of the first layer of diamond film.
And d, cutting, grinding and polishing the polycrystalline diamond thick film of the microwave energy transmission window prepared in the step d to form a window slice with the specified diameter, thickness, roughness and surface type precision, wherein the thickness of the window slice is 0.2-5mm, the diameter phi is 1-200mm, the surface roughness is less than or equal to 100nm, the surface flatness is less than or equal to 10 mu m, and the thickness tolerance is less than or equal to 10 mu m.
The invention has the beneficial effects that:
(1) the polycrystalline diamond thick film is a double-layer columnar crystal structure with a nucleation surface positioned in the middle layer and a growth layer positioned on two end surfaces, and the diamond film with the structure has small internal crystal grain size and large crystal boundary density, improves the overall strength of the diamond thick film, has few internal defects, reduces dielectric loss, and meets the application requirements of megawatt high-power microwave windows.
(2) The preparation method adopts step growth, compared with the conventional one-time growth method, the time and the thickness of single growth are reduced, the grain size of the growth surface of each layer of the diamond thick film prepared by the method is correspondingly reduced, and the purposes of refining the grain of the growth surface, increasing the grain boundary and increasing the bending strength of the growth surface are achieved.
(3) The step growth process inhibits the increase of black defects in the diamond thick film, reduces the size and density of the black defects, reduces the overall defects of the diamond thick film and reduces the dielectric loss.
(4) Compared with a single growth process, when the diamond thick film with the same thickness and the same quality is prepared by the step growth method, the deposition rate of the diamond thick film can be properly improved and the preparation efficiency is improved due to the control of internal defects, so that the continuous operation time of a system is reduced and the failure probability of the system is reduced.
Drawings
FIG. 1 is a schematic diagram of a two-layer diamond thick film structure of the present invention;
FIG. 2 is a scanning electron microscope image of a cross section of a first layer of a diamond thick film;
FIG. 3 is a scanning electron microscope image of a section of a double-layer diamond thick film;
FIG. 4 is a scanning electron microscope image of a double-layer columnar crystal structure;
FIG. 5 is a scanning electron microscope image of a single growth diamond thick film;
FIG. 6 is an optical microscopic image of black defects inside a double-layer diamond film obtained by two growth steps;
fig. 7 is an optical microscopic image of black defects inside a single-layer diamond thick film obtained by single growth.
In the figure: 1. a first diamond film; 2. a second layer of diamond film; 3. a nucleation surface; 4. and (4) growing the surface.
Detailed Description
The chemical vapor deposition method of the invention preferably adopts microwave plasma chemical vapor deposition without electrode pollution, and can also adopt direct current arc chemical vapor deposition or hot wire chemical vapor deposition and the like. In the preparation process, after the nucleation surface of the first layer of diamond film is treated, the growth surface of the first layer of diamond film is brazed on a substrate, then the deposition growth of the second layer of diamond film is carried out, and the purpose of brazing the treated first layer of diamond film and the substrate is to ensure the uniformity and controllability of the temperature of the second secondary long-time large-size diamond thick film and prevent the large-size diamond film from deforming and even cracking under the heating of uneven plasma. The first layer of diamond film is fully contacted with the substrate, and the substrate indirectly adjusts the heat dissipation of different areas of the first layer of diamond film, thereby achieving the purpose of reducing temperature difference and deformation. Under the condition of ensuring the temperature uniformity and controllability of the diamond film, the first layer of diamond can also be connected with the substrate by other modes (for example, adopting atomic bonding or vacuum adsorption and the like), or a second layer of diamond film is directly grown on the nucleation surface of the first layer of diamond film, especially the diamond film with the diameter phi less than or equal to 30 mm.
The diamond thick film prepared by the method is of a double-layer columnar crystal structure, and more layers of diamond films can be continuously epitaxially grown on the growth surfaces of the first layer of diamond film and the second layer of diamond film prepared by the method according to specific requirements, so that a multilayer columnar crystal structure with a nucleation surface positioned in the diamond is obtained on the basis of two layers. The diamond thick film window sheet prepared by the invention has different thickness of 0.2-5mm according to application requirements, and meets the use requirements of megawatt high-power microwave energy transmission windows: tn = N λ/2, t is the thickness, N is the refractive index, N is a positive integer, and λ is the incident microwave frequency. The diamond prepared by the invention is suitable for the application of megawatt high-power microwave windows, and can also be applied to other related applications needing high-strength or low-loss or high-heat-conducting materials.
The present invention will be further described with reference to the following examples.
Example 1
A2.45 GHz microwave plasma chemical vapor deposition device is adopted to deposit a first diamond film with the diameter of 50mm and the thickness of 0.41mm on the surface of a silicon substrate under the conditions of 10kW input microwave power, 1L hydrogen and 0.05L methane input temperature of 1050 ℃, and the growth rate is 5 mu m/h. Polishing the first diamond film nucleation surface of the separation substrate, directly placing the polished first diamond film on a deposition table of chemical vapor deposition equipment, etching for 1 hour under the condition of hydrogen plasma to remove surface pollution, and continuously growing a second polycrystalline diamond film on the polished first diamond film nucleation surface to a thickness of 0.42mm, wherein the growth conditions are the same as those of the first layer; after the growth is completed, a high-strength low-loss polycrystalline diamond thick film with a total thickness of about 0.83mm is obtained (as shown in the structural schematic diagram of fig. 1).
The cross section of the first diamond film with the thickness of 0.41mm is characterized by a scanning electron microscope, and the result is shown in figure 2, and an obvious columnar crystal structure is shown, wherein fine compact crystal grains with a nucleation surface 3 at the bottom end are initially grown, conical columnar crystal grains with a growth surface 4 at the upper end are grown, and the size of the crystal grains of the growth surface is obviously larger than that of the nucleation surface.
Scanning electron microscope characterization is carried out on the section of the diamond film with the nucleation surface of 0.83mm thickness positioned in the middle layer obtained by the two-time growth, and the result is shown in figure 3, which shows an obvious double-layer structure, wherein the reference numeral 1 refers to a first layer of the diamond film; reference numeral 2 is a second diamond film; reference numeral 3 is the middle nucleation layer.
Performing scanning electron microscope characterization on the double-layer columnar crystal structure of the diamond film with 0.83mm thick nucleation surface positioned in the middle layer obtained by the two-time growth with magnification, wherein the result is shown in figure 4, and 1 is the columnar crystal structure of the first layer of the diamond film; 3, a compact grain structure of the middle diamond-shaped nuclear layer; and 2 is a second layer of diamond film columnar crystal grain structure.
Example 2
A915 MHz microwave plasma chemical vapor deposition device is adopted to deposit a first diamond film with the diameter of 127mm and the thickness of 1.2mm on the surface of a silicon substrate under the conditions of input microwave power of 60kW, hydrogen of 5L and methane of 0.2L and the temperature of 1100 ℃, and the growth rate is 5 mu m/h. And polishing the nucleation surface of the first layer of diamond film of the separation substrate, and brazing the growth surface of the polished first layer of diamond film to the molybdenum substrate. And placing the brazed first layer of diamond film into chemical vapor deposition equipment, etching for 1 hour under the condition of hydrogen plasma to remove surface pollution, and continuously growing a second layer of polycrystalline diamond film on the polished nuclear surface of the first layer of diamond film to a thickness of 1.2mm, wherein the growth conditions are the same as those of the first layer. After the growth is completed, the molybdenum substrate is separated to obtain a high-strength low-loss polycrystalline diamond thick film with the total thickness of about 2.4 mm.
Cutting the obtained diamond thick film with the nucleation surface positioned in the middle layer and the growth surface positioned on the two end surfaces, wherein the diameter of the double-layer columnar crystal structure is 127mm and the thickness is 2.4mm, cutting the diamond thick film into a wafer with the diameter of 100mm by a laser, processing the two surfaces of the wafer into the thickness of 1.85mm by a diamond grinding and polishing machine, wherein the surface roughness is less than or equal to 10nm, the flatness is less than or equal to 10 mu m, the thickness tolerance is less than or equal to 10 mu m, and the performance of the diamond thick film is tested toLoss tangent tan delta under 310Mpa and 170GHz is less than or equal to 5 multiplied by 10-5The thermal conductivity is more than or equal to 1800W/m.K. The processed high-strength low-loss diamond thick film window is metallized and sealed to form a microwave window, and the microwave window is applied to a 170GHz megawatt high-power microwave transmission line window for the microwave heating of a fusion reactor.
Example 3
A2.45 Ghz microwave plasma chemical vapor deposition device is adopted to deposit a first diamond film with the diameter of 50mm and the thickness of 0.65mm on the surface of a silicon substrate under the conditions of 10kW input microwave power, 1L of hydrogen and 0.05L of methane and the temperature of 1050 ℃, and the growth rate is 4 mu m/h. And polishing the first diamond film nucleation surface of the separation substrate, directly placing the polished first diamond film on a deposition table of chemical vapor deposition equipment, etching for 1 hour under the condition of hydrogen plasma to remove surface pollution, and continuously growing a second polycrystalline diamond film on the polished first diamond film nucleation surface to a thickness of 0.65mm, wherein the growth conditions are the same as those of the first layer. After the growth is completed, the molybdenum substrate is separated to obtain a high-strength low-loss polycrystalline diamond thick film with the total thickness of about 1.3 mm.
Cutting the obtained diamond thick film with 50mm diameter and 1.3mm thickness of the double-layer columnar crystal structure with the nucleation surface positioned in the middle layer of the diamond film and the growth surface positioned on the two side surfaces by a laser into wafers with 49mm diameter, processing the two sides of the wafer to be 0.9mm thick by a diamond grinding and polishing machine, wherein the surface roughness is less than or equal to 10nm, the flatness is less than or equal to 10 mu m, the thickness tolerance is less than or equal to 10 mu m, the performance of the diamond thick film is tested to meet the conditions that the strength is more than or equal to 350MPa, and the loss tangent tan delta under 140GHz is less-5The thermal conductivity is more than or equal to 1800W/m.K. The processed high-strength low-loss diamond thick film window is metallized and sealed to form a microwave window, and the microwave window is applied to a 140GHz megawatt high-power gyrotron.
Comparative example 1
Adopting a 2.45Ghz microwave plasma chemical vapor deposition device, under the conditions of 10kW input microwave power, 1L of hydrogen and 0.05L of methane and 1050 ℃, continuously depositing a diamond film with the diameter of 50mm and the thickness of 0.81mm on the surface of a silicon substrate, and displaying an obvious columnar crystal structure by using a scanning electron microscope picture of the diamond film, wherein the bottom end of initial growth is fine compact crystal grains of a nucleation surface 3, the upper end of the growth is conical columnar crystal grains grown by a growth surface 4, and the grain size of the growth surface is obviously larger than that of the nucleation surface.
(one) the average flexural strength of the double-layered diamond film prepared in example 1 of the present invention was measured and compared with the flexural strength of the diamond film prepared in comparative example 1.
The first diamond film of 0.41mm thickness grown for the first time in example 1 was subjected to a strength test by a three-point bending method with a span of 16mm, an addition method of 0.2N/s, an average bending strength of the growth surface of 248MPa, an average bending strength of the nucleation surface of 403MPa, and a bending strength of the nucleation surface of 403MPa, which was significantly greater than that of the growth surface. The diamond film with 0.83mm thickness and with nucleation surfaces which grow twice and are positioned in the middle layer of the diamond film is subjected to strength test by adopting a three-point bending method, and the average bending strength of the growth surfaces at two sides respectively reaches 425MPa and 448 MPa. The diamond film with the thickness of 0.81mm grown in a single time in the comparative example 1 was subjected to a strength test, and the average bending strength of the growth surface was 191MPa and the average bending strength of the nucleation surface was 340 MPa. Experiments show that the bending strength of the diamond thick film with the nucleation surface positioned in the middle layer prepared by the method is not reduced but greatly improved along with the increase of the film thickness. Compared with the bending strength of the diamond film with the thickness of 0.81mm grown in a single time, the bending strength of the diamond film with the nucleation surface positioned in the middle layer prepared by the method is greatly improved.
(II) comparison of the internal structure of the diamond film prepared in example 1 of the present invention and the internal structure of the diamond film prepared in comparative example 1
The diamond film with 0.83mm thick nucleation surface positioned in the middle layer obtained by two growth processes in the embodiment 1 of the invention is subjected to double-sided polishing, the black defect inside the diamond film is observed by adopting an optical microscope, the optical image of the diamond film is shown in figure 6, a small amount of dotted black defects exist inside the diamond film, and the dimension of the diamond film is less than 100 mu m; polishing the double surfaces of the diamond film with the thickness of 0.81mm obtained by single growth in the comparative example 1, observing the internal black defects by using an optical microscope, wherein the optical image is shown in figure 7, a large number of cluster-shaped black defects exist in the diamond film, and the scale of most of the defects is close to 0.5-1 mm; the experimental result shows that the dimension and the density of the black defect in the diamond thick film with the nucleation surface positioned in the middle layer prepared by the method are obviously reduced compared with the diamond film with similar thickness grown in a single time.

Claims (9)

1. A polycrystalline diamond thick film for a microwave energy delivery window, comprising: the polycrystalline diamond thick film is of a double-layer columnar crystal structure and comprises a first layer of diamond film (1) and a second layer of diamond film (2), wherein the second layer of diamond film (2) grows on a nucleation surface (3) of the first layer of diamond film (1), and growing surfaces (4) of the first layer of diamond film and the second layer of diamond film are located at two ends.
2. A method of making a polycrystalline diamond thick film for a microwave energy delivery window as defined in claim 1 wherein: the thick film is prepared by adopting a step-by-step growth method, and the method comprises the following steps:
a. depositing a first layer of diamond film with a preset thickness on the surface of a substrate in a plasma atmosphere by adopting a chemical vapor deposition method, wherein the contact end of the first layer of diamond film and the substrate is a nucleation surface, and the end deviating from the substrate is a growth surface;
b. separating the first layer of diamond film from the substrate, processing the nucleation surface of the first layer of diamond film, and brazing the growth surface of the processed first layer of diamond film to the substrate;
c. placing the first layer of diamond film and the substrate which are brazed together into chemical vapor deposition equipment, and continuously growing a second layer of diamond film on the nucleation surface of the first layer of diamond film to a preset thickness;
d. and separating the substrate to obtain the high-strength low-loss double-layer polycrystalline diamond thick film.
3. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 2, wherein: the plasma atmosphere comprises hydrogen and methane.
4. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 3, wherein: the plasma atmosphere further comprises one or more of oxygen, argon and nitrogen.
5. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 4, wherein: the substrate material adopted by the growth and the brazing is one of silicon, molybdenum, tungsten or graphite.
6. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 5, wherein: the chemical vapor deposition method is a microwave plasma chemical vapor deposition method, the deposition growth conditions of the first layer of diamond film and the second layer of diamond film are the same, the average deposition growth rate is 0.5-15 mu m/h, the deposition temperature is 700-10 ℃, the methane concentration is 1-10%, the hydrogen flow is 50-5000sccm, the microwave input frequency is 2.45GHz or 915MHz, and the microwave input power is 5-75 kW.
7. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 6, wherein: the growth thickness of the first layer of diamond film and the second layer of diamond film is 0.1-2.5 mm.
8. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 7, wherein: in the step b, the processing of the nucleation surface of the first layer of the diamond film is grinding, polishing or plasma etching.
9. The method of preparing a polycrystalline diamond thick film for a microwave energy delivery window of claim 8, wherein: in the steps b and c, under the condition that the temperature uniformity and controllability of the diamond film can be ensured, the first layer of diamond can be connected with the substrate in other modes, or the second layer of diamond film can be directly grown on the nucleation surface of the first layer of diamond film.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05148088A (en) * 1991-04-26 1993-06-15 Nippon Steel Corp Method for growing diamond crystal
CN109722641A (en) * 2017-10-30 2019-05-07 深圳先进技术研究院 Diamond/graphene composite heat conduction film and preparation method thereof and cooling system
CN110416039A (en) * 2019-07-30 2019-11-05 中国电子科技集团公司第十二研究所 A kind of delivery of energy window of terahertz wave band vacuum device and preparation method thereof
CN111118471A (en) * 2020-01-15 2020-05-08 吉林大学 Preparation method of high-quality polycrystalline diamond film

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05148088A (en) * 1991-04-26 1993-06-15 Nippon Steel Corp Method for growing diamond crystal
CN109722641A (en) * 2017-10-30 2019-05-07 深圳先进技术研究院 Diamond/graphene composite heat conduction film and preparation method thereof and cooling system
CN110416039A (en) * 2019-07-30 2019-11-05 中国电子科技集团公司第十二研究所 A kind of delivery of energy window of terahertz wave band vacuum device and preparation method thereof
CN111118471A (en) * 2020-01-15 2020-05-08 吉林大学 Preparation method of high-quality polycrystalline diamond film

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