WO2020082844A1

WO2020082844A1 - Microwave plasma cvd device and method for synthesizing diamond using same

Info

Publication number: WO2020082844A1
Application number: PCT/CN2019/098507
Authority: WO
Inventors: 杨竣焜
Original assignee: 六晶科技有限公司
Priority date: 2018-10-25
Filing date: 2019-07-31
Publication date: 2020-04-30
Also published as: HK1252297A2

Abstract

A microwave plasma CVD device, comprising: a plasma cavity (100), a waveguide (200), an excitation probe (300), a microwave window (400), and a substrate support table. The microwave plasma CVD device is equipped with movable parts to facilitate adjustment of impedance in the plasma cavity (100), so as to maximize the absorption of microwaves, such that generated plasma is kept away from a quartz window. The shape of plasma is also changed near the substrate support table, so as to maximize contact between the plasma and the substrate support table, change the energy density of the plasma, or maintain the relative position of the deposition substrate and the plasma during growth.

Description

Microwave plasma CVD device and method for synthesizing diamond using the same

Technical field

The invention relates to the field of microwave plasma processing, in particular to a microwave plasma CVD device and a method for synthesizing diamond using the same.

Background technique

The microwave plasma CVD device is a process device that uses microwave energy to realize chemical vapor deposition, and has the advantages of large output, high quality, and low cost. The principle is that microwaves resonate in the plasma cavity, forming a strong electromagnetic field center area, ionizing the gas, forming a plasma, and then forming a solid substance deposit on the surface of the deposition substrate.

Microwave plasma CVD (MPCVD) is one of the methods for growing high quality single crystal diamond (SCD) and polycrystalline diamond (PCD). In order to reduce impurities and improve the crystalline quality of synthetic diamond, it is important to maintain the growth conditions while extending the continuous deposition time as far as possible to keep the plasma away from the microwave window usually made of quartz to reduce the corrosion of quartz to avoid release Impurity silicon and prevent damage to the quartz window.

Summary of the invention

Based on this, it is necessary to provide a microwave plasma CVD apparatus that can extend the continuous deposition time and keep the plasma away from the microwave window.

The technical scheme adopted by the present invention is:

A microwave plasma CVD device, including:

A plasma chamber, which includes a side wall, an upper short-circuit plate, and a lower short-circuit plate; wherein the upper short-circuit plate is provided at the upper portion of the side wall, and an opening for introducing microwaves is provided in the center; the lower short-circuit plate is movable It is provided on the lower part of the side wall; an air inlet is opened on the side wall;

A waveguide for introducing the microwave to the opening;

An excitation probe, which is in the form of a flange, includes a longitudinal probe portion and a lateral probe portion, the longitudinal probe portion is located at the center of the waveguide and extends into the plasma chamber, and the lateral probe portion is annular and located at the The end of the longitudinal probe section;

A microwave window for introducing the microwave into the plasma chamber and keeping the plasma chamber at a preset vacuum degree;

And a substrate cold water platform group, which includes an outer water cooling jacket and an inner water cooling platform movably disposed in the outer water cooling jacket, the inner water cooling platform is provided with a deposition substrate; at least the substrate cold water platform group Partly arranged in the plasma chamber and arranged opposite to the lateral probe;

Wherein, the distance between the upper surface of the outer water cooling jacket and the lower short-circuit plate is L2;

The distance between the table surface of the inner water-cooled table and the upper surface of the outer water-cooled jacket is L3;

L2 is adjusted by axially moving the lower short-circuit plate, and L3 is adjusted by axially moving the inner water-cooled stage.

In one of the embodiments, the side wall includes a cylindrical side wall, the upper short-circuit plate is disposed on an upper portion of the cylindrical side wall, and the lower short-circuit plate is movably disposed on the cylindrical side wall Lower part

The microwave window is clamped between the upper short circuit plate and the lateral probe;

The distance between the upper short-circuit plate and the lower short-circuit plate is L1, and L1 is adjusted by moving the lower short-circuit plate in the axial direction.

In one of the embodiments, the side wall includes a cylindrical side wall and a flange-shaped side wall, and the flange end of the flange-shaped side wall extends into and is movably disposed in the cylindrical side wall The upper short-circuit plate is provided on the upper portion of the cylindrical side wall, and the lower short-circuit plate is movably provided in the flange-shaped side wall;

The distance between the upper surface of the outer water-cooled jacket and the end surface of the flange end of the flange-shaped side wall is L5, and L5 is adjusted by moving the flange-shaped side wall axially.

In one of the embodiments, the side wall includes a cylindrical side wall, a flange-shaped first side wall and a flange-shaped second side wall, the flange end of the flange-shaped first side wall extends into and It is arranged in the cylindrical side wall; the flange end of the flange-shaped second side wall extends into and is movably arranged in the flange-shaped first side wall;

The upper short-circuit plate is arranged on the upper part of the cylindrical side wall, and the lower short-circuit plate is movably arranged in the flange-shaped second side wall;

The microwave window is provided between the lateral probe part and the substrate cold water platform group;

The distance between the upper surface of the outer water cooling jacket and the end face of the flange end of the flange-shaped second side wall is L6, and L6 is adjusted by axially moving the flange-shaped second side wall.

In one of the embodiments, the upper short circuit plate is movably disposed on the upper portion of the cylindrical side wall; or

The excitation probe is movably arranged in the waveguide;

The distance between the upper short-circuit plate and the lateral probe portion is L7, and L7 is adjusted by axially moving the upper short-circuit plate or the excitation probe.

In one of the embodiments, the microwave window has a flat plate shape, which is provided on the end surface of the flange end of the flange-shaped first side wall; or

The microwave window has a semi-circular cover shape, which is provided on the end surface of the flange end of the flange-shaped second side wall.

In one of the embodiments, the outer water cooling jacket of the substrate cold water platform group is movably disposed in the plasma chamber;

The distance between the bottom end of the excitation probe and the upper surface of the outer water cooling jacket is L4;

Adjusting L4 by axially moving the outer water-cooled jacket can also adjust L2 or L3 by moving the outer water-cooled jacket.

In one embodiment, the diameter of the inner water-cooled table is 80-300mm; the inner water-cooled table is -100-30mm higher than the upper surface of the outer water-cooled jacket.

In one embodiment, the table surface of the inner water-cooled table is lower than the upper surface of the outer water-cooled jacket, and the table surface of the inner water-cooled table is 0-100 mm lower than the upper surface of the outer water-cooled jacket.

The invention also provides a method for synthesizing diamond using a chemical vapor deposition process, which includes the following steps:

Install the microwave plasma CVD device described above;

Passing the first raw material gas into the plasma chamber through the gas inlet;

Using the waveguide and the excitation probe to emit microwaves into the plasma chamber; and

Passing a second raw material gas into the plasma chamber to form diamond on the deposition substrate;

Where, when the plasma is too close to the microwave window, adjust L1, L2, L4, L5 or L6 to keep the plasma away from the microwave window;

When the diamond is continuously grown on the deposition substrate to a suitable thickness, the substrate support table or the concave table is lowered to return the upper surface of the grown diamond to a proper position.

In one embodiment, the first raw material gas is at least one of hydrogen, helium, and argon; the second raw material gas is a hydrocarbon gas or a hydrocarbon gas and an oxygen-containing gas, a nitrogen-containing gas, and a boron-containing gas A mixture of at least one of gas and phosphorus-containing gas.

Compared with existing solutions, the present invention has the following beneficial effects:

The microwave plasma CVD apparatus provided by the present invention is provided with movable parts so that L2 and L3 are in an adjustable state. Such an arrangement is convenient for adjusting the impedance in the plasma chamber to maximize the absorption of microwaves and keep the generated plasma away from quartz At the same time, by changing the shape of the plasma in the vicinity of the cold plate group of the substrate, the contact between the plasma and the deposited substrate is maximized, the energy density of the plasma is changed, or the relative position of the deposited substrate and the plasma is maintained during growth.

When L4, L5 or L6 (especially L5 or L6) is in an adjustable state through further settings, the plasma can be better away from the quartz window, which can effectively prevent the window from becoming black and overheating after a long time operation of the plasma chamber. As a result, the efficiency of microwave transmission to the plasma decreases and the plasma etching window during operation causes the problem of releasing impurity silicon and affecting the quality of diamond growth.

BRIEF DESCRIPTION

1 is a schematic structural diagram of a microwave plasma CVD apparatus in Embodiment 1;

2 is a schematic diagram of a partial structure of a microwave plasma CVD apparatus in Embodiment 2;

Figure 3 is a schematic diagram of the structure of the substrate support table;

4 is one of the structural schematic diagrams of the microwave plasma CVD apparatus in Embodiment 3;

5 is a second structural schematic diagram of the microwave plasma CVD apparatus in Embodiment 3;

Among them, 100, plasma chamber; 101, side wall; 1011, cylindrical side wall; 1012, flange-shaped side wall; 102, upper short circuit plate; 103, lower short circuit plate; 104, opening; 105, air inlet; 1061, flange tube; 1062, flange end; 111,112, threaded rod; 200, waveguide; 300, excitation probe; 301, longitudinal probe section; 302, transverse probe section; 400, microwave window, 500, substrate cold water table Group; 501, internal water cooling platform; 502, cooling pipeline; 503, external water cooling jacket.

detailed description

In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to related drawings. The drawings show preferred embodiments of the invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

It should be noted that when an element is said to be “fixed” to another element, it can be directly on the other element or there can also be a centered element. When an element is considered to be "connected" to another element, it may be directly connected to another element or there may be a centered element at the same time.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terminology used in the description of the present invention herein is for the purpose of describing specific embodiments, and is not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more related listed items.

Example 1

As shown in FIG. 1, a microwave plasma CVD apparatus according to an embodiment of the present invention includes a plasma chamber 100, a waveguide 200, an excitation probe 300, a microwave window 400, and a substrate cold water stage group 500.

Referring to FIG. 1, the plasma chamber 100 includes a side wall 101, an upper short-circuit plate 102, and a lower short-circuit plate 103; wherein, the upper short-circuit plate 102 is provided on the upper portion of the side wall 101, and an opening 104 for introducing microwaves is formed in the center thereof; The short-circuit plate 103 is movably provided at the lower part of the side wall 101; an air inlet 105 is opened on the side wall 101. The gas inlet 104 is used to introduce the raw material gas into the plasma chamber 100; the microwave plasma CVD apparatus is further provided with an gas outlet (not shown in the figure) for drawing out the gas in the plasma chamber 100.

The lower short-circuit plate 103 can move its axial position by any suitable method in the prior art, for example, using a sliding method (such as a matching method of a threaded rod and a gear assembly). In one embodiment, the threaded rod 112 is installed on the lower short-circuit plate 103, and the threaded rod 112 is driven to move up and down through the gear assembly, thereby driving the lower short-circuit plate to move up and down axially.

The shape of the microwave-introducing opening 104 is not limited here, and a round or elliptical shape is generally used.

The waveguide 200 is used to introduce the microwave to the opening 104. In one example, the waveguide 200 is a cylindrical waveguide provided directly above the circular opening 104, and the bottom end of the waveguide 200 is connected to the upper short-circuit plate 102. In one example, the bottom end of the waveguide 200 is integrally formed with the edge of the opening 104 of the upper short-circuit plate 102. For the waveguide, metals such as stainless steel, molybdenum, or aluminum are suitable for use, but in order to reduce microwave transmission loss, the inner surface is preferably plated with a metal with low resistivity, such as gold, silver, or copper. The wavelength of the microwave band is not limited here, as long as they have a wavelength that can generate plasma.

The excitation probe 300 is used to introduce microwaves into the plasma chamber 100, which is flange-shaped and includes a longitudinal probe portion 301 and a lateral probe portion 302. The longitudinal probe portion 301 is located in the center of the waveguide 200 and the end extends into the

plasma chamber

100, 302 has a ring shape and is located at the end of the longitudinal probe portion 301. The longitudinal probe portion 301 and the lateral probe portion 302 have different diameters, and the diameter D5 of the lateral probe portion 302 is larger than the diameter D4 of the longitudinal probe portion 301. In one example, the excitation probe 300 is a water-cooled excitation probe.

The microwave window 400 is used to introduce the microwave into the plasma chamber 100 and keep the plasma chamber 100 at a preset vacuum degree. The microwave window 400 is made of a microwave-permeable material such as quartz.

As shown in FIG. 3, the substrate cold water platform group 500 includes an outer water cooling jacket 503 and an inner water cooling platform 501 movably disposed in the outer water cooling jacket 503, and the inner water cooling platform 501 is provided with a deposition substrate; the substrate cold water platform group At least part of 500 is disposed in the plasma chamber 100, and is disposed opposite to the lateral probe 302. The lower part of the substrate cold water group 500 protrudes from the plasma chamber 100 through the opening of the lower short-circuit plate 103.

The distance between the upper surface of the outer water-cooling jacket 503 and the lower short-circuit plate 103 is defined as L2; the distance between the table surface of the inner water-cooling platform 501 and the upper surface of the outer water-cooling jacket 503 is defined as L3; The plate 103 can be used to adjust L2, and the L3 can be adjusted by moving the internal water cooling stage 501 axially.

During the operation of the microwave plasma CVD apparatus of this embodiment, microwaves are introduced into the plasma chamber 100 and form a plasma where the electromagnetic energy is sufficiently large. By adjusting L2 and L3, the impedance matching with the plasma chamber 100 can be improved to maximize the absorption of microwaves and keep the generated plasma away from the quartz window. At the same time, the plasma can also be changed by changing the shape of the plasma near the substrate cold water stage group. Maximize contact with the deposited substrate, change the energy density of the plasma, or maintain the relative position of the deposited substrate and the plasma while growing. If the substrate cold water stage of the microwave plasma CVD device is not capable of adjusting L3, after the diamond grows thicker, the diamond surface leaves the optimal growth environment because it is too deep into the plasma. At this time, the operation must be stopped to replace the substrate stage , Re-growth, and stop the system may have the following problems 1) easy to introduce pollution, affecting quality; 2) the process of starting growth and suspension process environment is different from the normal growth process, affecting the continuity of diamond crystal quality. The microwave plasma CVD apparatus in this embodiment can effectively avoid this problem.

In this embodiment, the side wall 101 includes a cylindrical side wall 1011 and a flange-shaped side wall 1012. The flange end 1062 of the flange-shaped side wall 1012 extends into and is movably disposed in the cylindrical side wall 1011. The inner diameter D1 of the cylindrical side wall 1011 is larger than the inner diameter D2 of the flange-shaped side wall 1012; the upper short-circuit plate 102 is provided on the upper portion of the cylindrical side wall 1011, and the lower short-circuit plate 103 is movably provided on the flange of the flange-shaped side wall Inside the tube 1061; the microwave window 400 is clamped between the upper short-circuit plate 102 and the lateral probe 302.

The distance between the upper surface of the outer water-cooling jacket 503 and the end surface of the flange end 1062 of the flange-shaped side wall is L5, and L5 is adjusted by axially moving the flange-shaped side wall 1012.

The applicant has found through a lot of experiments that for the plasma to stay away from the microwave window to prevent the microwave window from being easily etched and blackened when diamond is grown for a long time, L5 is a very critical adjustment parameter; by adjusting L5, the plasma can be better away from the quartz window , It can effectively avoid the problem that the window is easily blackened and overheated after a long time operation of the plasma chamber, which causes the efficiency of microwave transmission to the plasma to decrease and the plasma etching window during operation causes the release of impurity silicon to affect the diamond growth quality. The microwave plasma CVD apparatus of this embodiment can realize the adjustment of L5, and thus can effectively solve the above problems.

The distance between the upper short-circuit plate 102 and the lower short-circuit plate 103 is L1, and L1 is adjusted by moving the lower short-circuit plate 103 in the axial direction. In a preferred example, the upper short-circuit plate 102 is movably provided on the upper portion of the side wall 101, so that L1 can also be adjusted by moving the upper short-circuit plate 102.

In this embodiment, the outer water cooling jacket 503 of the substrate cold water stage group is movably disposed in the plasma chamber 100. The distance between the bottom end of the excitation probe 300 and the upper surface of the outer water cooling jacket 503 is defined as L4, and then the outer water cooling jacket 503 can be used to adjust L4. Of course, L2 or L3 can also be adjusted by moving the outer water cooling jacket.

When the microwave plasma CVD apparatus is in operation, the plasma is expected to be positioned and spread over the deposition substrate. By adjusting L1, L2, L4, and L5, the shape of the plasma can be changed to better cover the deposition substrate.

Preferably, the diameter of the tabletop of the inner water-cooled table 501 is 80-300 mm; the tabletop of the inner water-cooled table 501 is higher than the upper surface of the outer water-cooled jacket 503 by -100-30 mm. Among them, the range of 0 ～ 30mm represents the case where the tabletop of the inner water-cooled table is higher than the upper surface of the outer water-cooled jacket, that is, the tabletop of the inner water-cooled table is 0 ～ 30mm higher than the upper surface of the outer water-cooled jacket; the range of −100 ～ 0mm represents The case of the inner water-cooled table is lower than the upper surface of the outer water-cooled jacket, that is, the inner water-cooled table is 0-100 mm lower than the upper surface of the outer water-cooled jacket. The diameter of the table of the internal water-cooled stage 501 will affect the shape and energy density of the plasma. When the diameter of the table of the internal water-cooled stage 501 is 80-300mm, the substrate surface power density and ion coverage area are better under the same power input; If the diameter of the internal water cooling stage is too small, it will affect the output; when the diameter is too large, the plasma cannot cover the substrate surface evenly.

Further, the table surface of the inner water cooling table 501 is lower than the upper surface of the outer water cooling jacket 503, and the table surface of the inner water cooling table 501 is lower than the upper surface of the outer water cooling jacket 503 by 0 to 100 mm.

Optionally, the upper short-circuit plate 102 is movably provided on the upper part of the side wall 101; the excitation probe 300 is movably provided in the waveguide 200; by selectively moving the upper short-circuit plate 102, the lower short-circuit plate 103, the excitation probe 300, the inner One or both of the water cooling stage 501, the outer water cooling jacket 503, and the flange-shaped side wall 1012 are used to adjust L1, L2, L3, L4, or L5. For example, L1 can be adjusted by vertically moving the upper short-circuit plate 102 and the lower short-circuit plate 103; L2 can be adjusted by vertically moving the lower short-circuit plate 103 and the outer water-cooling jacket 503; L3 can be adjusted by moving the inner water-cooling stage 501 axially L4 can be adjusted by axially moving the excitation probe 300 or the outer water-cooled jacket 503; L5 can be adjusted by axially moving the outer water-cooled jacket 503 or the flange-shaped side wall 1012.

Preferably, L2 is 100 to 200 mm, L3 is 30 to 100 mm; more preferably, L1 is 200 to 400 mm, L4 is 10 to 100 mm, and L5 is -30 to 30 mm; the distance between the components in the device When the initial value is set within the above range, the matching impedance of the plasma chamber 100 can be relatively low, and ion bodies can be effectively generated near the substrate.

The upper short-circuit plate 102 can move its axial position by any suitable method in the prior art, for example, using a sliding method (such as a matching method of a threaded rod and a gear assembly). As shown in FIG. 1, in one example, the threaded rod 111 is installed on the upper short-circuit plate 102, and the threaded rod 111 is driven to move up and down through the gear assembly, thereby driving the upper short-circuit plate to move vertically. Further, the upper conductive short 102 is fixedly connected with the waveguide 200 and the excitation probe 300, and the axial movement of the upper conductive short 102 and the excitation probe 300 can be driven by the up and down movement of the threaded rod 111.

In this embodiment, a cooling pipeline 502 is provided in the substrate cold water platform group. The cooling medium flows in the cooling pipeline 502, and water can be selected as the cooling medium, and the circulating cooling can also be achieved through the pump body.

In this embodiment, the microwave plasma CVD apparatus further includes a gas flow system, which is used to deliver the raw material gas into the plasma chamber and remove the gas from the plasma chamber.

Example 2

As shown in FIG. 2, a microwave plasma CVD apparatus according to another embodiment of the present invention is different from Embodiment 1 in that the side wall 101 includes a cylindrical side wall 1011 and the upper short circuit plate 102 is provided on the cylindrical side wall In the upper part of 1011, the lower short-circuit plate 103 is movably arranged in the lower part of the cylindrical side wall 1011;

Example 1.

Example 3

As shown in FIGS. 4 and 5, a microwave plasma CVD apparatus according to an embodiment of the present invention includes a plasma chamber 100, a waveguide 200, an excitation probe 300, a microwave window 400, and a substrate cold water stage group 500.

The plasma chamber 100 includes a side wall 101, an upper short-circuit plate 102, and a lower short-circuit plate 103; wherein, the upper short-circuit plate 102 is provided on the upper portion of the side wall 101, and an opening 104 for introducing microwaves is opened in the center; the lower short-circuit plate 103 is movable It is provided on the lower part of the side wall 101; an air inlet 105 is opened on the side wall 101. The gas inlet 104 is used to introduce the raw material gas into the plasma chamber 100; the microwave plasma CVD apparatus is further provided with an gas outlet (not shown in the figure) for drawing out the gas in the plasma chamber 100.

The excitation probe 300 is used to introduce microwaves into the plasma chamber 100, which is flange-shaped and includes a longitudinal probe portion 301 and a lateral probe portion 302. The longitudinal probe portion 301 is located in the center of the waveguide 200 and the end extends into the plasma chamber 100, the lateral probe portion 302 has a ring shape and is located at the end of the longitudinal probe portion 301. The longitudinal probe portion 301 and the lateral probe portion 302 have different diameters, and the diameter of the lateral probe portion 302 is larger than the longitudinal probe portion 301. In one example, the excitation probe 300 is a water-cooled excitation probe.

As shown in FIG. 3, the substrate cold water platform group 500 includes an outer water cooling jacket 503 and an inner water cooling platform 501 movably disposed in the outer water cooling jacket 503, and a deposition substrate is provided on the inner water cooling platform 501; At least part of 500 is disposed in the plasma chamber 100, and is disposed opposite to the lateral probe 302. The lower part of the substrate cold water group 500 protrudes from the plasma chamber 100 through the opening of the lower short-circuit plate 103.

The distance between the upper surface of the outer water-cooled jacket 503 and the lower short-circuit plate 103 is defined as L2; the distance between the table surface of the inner water-cooled platform 501 and the upper surface of the outer water-cooled jacket 503 is L3; by moving the lower short-circuit plate 103 axially Used to adjust L2, adjust L3 by moving the internal water cooling stage 501 axially.

Preferably, the diameter of the tabletop of the inner water-cooled table 501 is 80-300 mm; the tabletop of the inner water-cooled table 501 is higher than the upper surface of the outer water-cooled jacket 503 by -100-30 mm. Among them, the range of 0 ～ 30mm represents the case where the tabletop of the inner water-cooled table is higher than the upper surface of the outer water-cooled jacket, that is, the tabletop of the inner water-cooled table is 0 ～ 30mm higher than the upper surface of the outer water-cooled jacket; The case of the inner water-cooled table is lower than the upper surface of the outer water-cooled jacket, that is, the inner water-cooled table is 0-100 mm lower than the upper surface of the outer water-cooled jacket. The diameter of the table of the internal water-cooled stage 501 will affect the shape and energy density of the plasma. When the diameter of the table of the internal water-cooled stage 501 is 80-300mm, the substrate surface power density and ion coverage area are better under the same power input; If the diameter of the internal water cooling table is too small, it will affect the output; when the diameter is too large, the ion coverage area is too large, and the plasma cannot cover the substrate surface evenly.

Further, the table surface of the inner water cooling table 501 is lower than the upper surface of the outer water cooling jacket 503, and the distance between the table surface of the inner water cooling table 501 and the upper surface of the outer water cooling jacket 503 is 0-100 mm.

The above is the same as Embodiment 1 and Embodiment 2, and this embodiment is different from Embodiment 1 and Embodiment 2 in that:

In this embodiment, the side wall 101 includes a cylindrical side wall 1011, a flange-shaped first side wall 1013, and a flange-shaped second side wall 1014. The flange end of the flange-shaped first side wall 1013 extends into and Set in the cylindrical side wall 1011; the flange end of the flange-shaped second side wall 1014 extends into and is movably set in the flange-shaped first side wall 1013;

The upper short-circuit plate 102 is provided on the upper part of the cylindrical side wall 1011, and the lower short-circuit plate 103 is movably provided in the flange-shaped second side wall 1014;

The microwave window 400 is provided between the horizontal probe part 302 and the substrate cold water stage group 500;

The distance between the outer water-cooling jacket 503 and the end face of the flange end of the flange-shaped second side wall 1014 is L6, which can be used to adjust L6 by axially moving the flange-shaped second side wall 1014.

Similar to L5, L6 is also a very critical adjustment parameter; similarly, by adjusting L6, the plasma can be better away from the quartz window, which can effectively prevent the window from turning black and overheating after long-term operation of the plasma chamber, resulting in microwave conduction Due to the decrease in plasma efficiency and the plasma etching window during operation, silicon impurities are released to affect the quality of diamond growth. The microwave plasma CVD apparatus of this embodiment can realize the adjustment of L6, and thus can effectively solve the above problems.

In this embodiment, the inner diameter D1 of the cylindrical side wall 1011, the inner diameter D2 of the flange-shaped first side wall 1013, and the inner diameter D3 of the flange-shaped second side wall 1014 gradually decrease; since the flange-shaped second side wall The inner diameter of is smaller than that of the flange-shaped first side wall and is closer to the plasma, which can more effectively change the resonance mode near the ion body, and the plasma is generated in the resonance mode where the energy density is high. Preferably, the inner diameter D1 of the cylindrical side wall 1011 is 400-800 mm, the inner diameter D2 of the flange-shaped first side wall is 300-700 mm, and the inner diameter D3 of the flange-shaped second side wall is 100-600 mm.

Optionally, the upper short-circuit plate 102 is movably provided on the upper portion of the cylindrical side wall 1011; or the excitation probe 300 is movably provided in the waveguide 200; the distance between the upper short-circuit plate 102 and the lateral probe portion 302 is defined as L7, adjust L7 by axially moving the upper short-circuit plate 102 or the excitation probe 300.

Preferably, L2 is 100-200mm, L3 is -100-30mm; more preferably, L4 is 300-600mm, L6 is -30-30mm, L7 is 30mm-100mm; the distance between the components in the device When the initial value is set within the above range, the matching impedance of the plasma chamber 100 can be relatively low, and ion bodies can be effectively generated near the substrate.

Optionally, as shown in FIG. 4, the microwave window 400 has a flat plate shape, which is provided on the end surface of the flange end of the flange-shaped first side wall 1013.

Optionally, as shown in FIG. 5, the microwave window 400 has a semi-circular cover shape, which is provided on the end face of the flange end of the flange-shaped second side wall 1014.

Compared with the semi-circular hood-shaped microwave window, the contact area of the flat-shaped microwave window and the plasma is smaller.

Alternatively, L2, L3, L4, L6, or L7 can be adjusted by selectively moving one or both of the upper short-circuit plate 102, the lower short-circuit plate 103, the excitation probe 300, the inner water cooling stage 501, and the outer water cooling jacket 503. For example, L2 can be adjusted by axially moving the lower short-circuit plate 103 and the outer water cooling jacket 503; L3 can be adjusted by axially moving the inner water cooling stage 501; L4 can be adjusted by axially moving the excitation probe 300 or the outer water cooling jacket 503 L6 can be adjusted by axially moving the outer water-cooling jacket 503 or the flange-shaped second side wall 1014; L7 can be adjusted by axially moving the upper short-circuit plate 102 or the excitation probe 300.

Example 4

This embodiment provides a method for synthesizing diamond using a chemical vapor deposition process, which includes the following steps:

Set the microwave plasma CVD apparatus described in Embodiment 1, 2 or 3;

Wherein the first raw material gas is at least one of hydrogen, helium and argon; the second raw material gas is hydrocarbon gas or hydrocarbon gas and oxygen-containing gas (such as O ₂ , CO, CO ₂ ) Nitrogen gas (such as N ₂ , NH ₃ , NO, NO ₂ ), boron-containing gas (BF ₃ , BCl ₃ , B ₂ H ₆ , C ₆ H ₁₅ B, C ₃ H ₉ B), phosphorus-containing gas (such as P _4. A mixture of at least one of PF ₃ , PF ₅ and PH ₃ ).

In this method, proper introduction of some doping gas containing, for example, boron-containing gas, phosphorous-containing gas, etc. can change the performance parameters of the diamond deposited on the surface of the deposited substrate.

In one example, “too close” means that the plasma is 0.01-30 mm away from the microwave window.

In one example, "appropriate thickness" refers to the continuous growth of diamond on the deposition substrate to a thickness of 0.01 mm to 9 mm, preferably 0.01 mm to 4 mm; when the diamond is too thick, the environment of the diamond surface is different from the initial Larger will affect its further growth. Since the thickness of diamond growing on the surface of the deposited substrate may vary, when the thickness of diamond is in the range of "0.01 mm to 9 mm", it can be understood as an appropriate thickness here.

The technical features of the above-mentioned embodiments can be arbitrarily combined. In order to simplify the description, all possible combinations of the technical features in the above-mentioned embodiments are not described. All should be considered within the scope of this description.

The above-mentioned embodiments only express several embodiments of the present invention, and their descriptions are more specific and detailed, but they should not be construed as limiting the patent scope of the invention. It should be noted that, those of ordinary skill in the art, without departing from the concept of the present invention, can also make several modifications and improvements, which all fall within the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

A microwave plasma CVD device, characterized in that it includes:

A plasma chamber, which includes a side wall, an upper short-circuit plate, and a lower short-circuit plate; wherein the upper short-circuit plate is provided at the upper portion of the side wall, and an opening for introducing microwaves is provided in the center; the lower short-circuit plate is movable It is provided on the lower part of the side wall; an air inlet is opened on the side wall;

A waveguide for introducing the microwave to the opening;

An excitation probe, which is in the form of a flange, includes a longitudinal probe portion and a lateral probe portion, the longitudinal probe portion is located at the center of the waveguide and extends into the plasma chamber, and the lateral probe portion is annular and located at the The end of the longitudinal probe section;

A microwave window for introducing the microwave into the plasma chamber and keeping the plasma chamber at a preset vacuum degree;

And a substrate cold water platform group, which includes an outer water cooling jacket and an inner water cooling platform movably disposed in the outer water cooling jacket, the inner water cooling platform is provided with a deposition substrate; at least the substrate cold water platform group Partly arranged in the plasma chamber and arranged opposite to the lateral probe;

Wherein, the distance between the upper surface of the outer water cooling jacket and the lower short-circuit plate is L2;

The distance between the table surface of the inner water-cooled table and the upper surface of the outer water-cooled jacket is L3;

L2 is adjusted by axially moving the lower short-circuit plate, and L3 is adjusted by axially moving the inner water-cooled stage.
The microwave plasma CVD apparatus according to claim 1, wherein the side wall includes a cylindrical side wall, the upper short circuit plate is provided on an upper portion of the cylindrical side wall, and the lower short circuit plate is movable It is provided at the lower part of the cylindrical side wall;

The microwave window is clamped between the upper short circuit plate and the lateral probe;

The distance between the upper short-circuit plate and the lower short-circuit plate is L1, and L1 is adjusted by moving the lower short-circuit plate in the axial direction.
The microwave plasma CVD apparatus according to claim 1, wherein the side wall includes a cylindrical side wall and a flange-shaped side wall, and the flange end of the flange-shaped side wall extends into and is movable Is provided in the cylindrical side wall; the upper short-circuit plate is provided in the upper portion of the cylindrical side wall, and the lower short-circuit plate is movably provided in the flange-shaped side wall;

The microwave window is clamped between the upper short circuit plate and the lateral probe;

The distance between the upper surface of the outer water-cooled jacket and the end face of the flange end of the flange-shaped side wall is L5, and L5 is adjusted by axially moving the flange-shaped side wall;

The distance between the upper short-circuit plate and the lower short-circuit plate is L1, and L1 is adjusted by moving the lower short-circuit plate in the axial direction.
The microwave plasma CVD apparatus according to claim 1, wherein the sidewall includes a cylindrical sidewall, a flange-shaped first sidewall, and a flange-shaped second sidewall, the flange-shaped first The flange end of the side wall extends into and is arranged in the cylindrical side wall; the flange end of the flange-shaped second side wall extends into and is movably arranged on the first side of the flange shape Inside the wall

The upper short-circuit plate is arranged on the upper part of the cylindrical side wall, and the lower short-circuit plate is movably arranged in the flange-shaped second side wall;

The microwave window is provided between the lateral probe part and the substrate cold water platform group;

The distance between the upper surface of the outer water cooling jacket and the end face of the flange end of the flange-shaped second side wall is L6, and L6 is adjusted by axially moving the flange-shaped second side wall.
The microwave plasma CVD apparatus according to claim 4, wherein:

The upper short-circuit plate is movably arranged on the upper part of the cylindrical side wall; or

The excitation probe is movably arranged in the waveguide;

The distance between the upper short-circuit plate and the lateral probe portion is L7, and L7 is adjusted by axially moving the upper short-circuit plate or the excitation probe.
The microwave plasma CVD apparatus according to claim 4, wherein the microwave window has a flat plate shape, which is provided on an end surface of the flange end of the flange-shaped first side wall; or

The microwave window has a semi-circular cover shape, which is provided on the end surface of the flange end of the flange-shaped second side wall.
The microwave plasma CVD apparatus according to claim 1, wherein:

The outer water cooling jacket of the substrate cold water platform group is movably arranged in the plasma chamber;

The distance between the bottom end of the excitation probe and the upper surface of the outer water cooling jacket is L4;

Adjusting L4 by axially moving the outer water-cooled jacket can also adjust L2 or L3 by moving the outer water-cooled jacket.
The microwave plasma CVD apparatus according to claim 1, wherein the diameter of the table of the internal water-cooled table is 80-300mm;

The table surface of the inner water-cooled table is -100 to 30 mm higher than the upper surface of the outer water-cooled jacket.
A method for synthesizing diamond using a chemical vapor deposition process, which is characterized by the following steps:

The microwave plasma CVD apparatus according to any one of claims 1 to 8 is provided;

Passing the first raw material gas into the plasma chamber through the gas inlet;

Using the waveguide and the excitation probe to emit microwaves into the plasma chamber; and

Passing a second raw material gas into the plasma chamber to form diamond on the deposition substrate;

Where, when the plasma is too close to the microwave window, adjust L1, L2, L4, L5 or L6 to keep the plasma away from the microwave window;

When the diamond is continuously grown to a suitable thickness on the deposition substrate, the internal water cooling stage is lowered to return the upper surface of the grown diamond to a proper position.
The method according to claim 9, wherein the first raw material gas is at least one of hydrogen, helium and argon; the second raw material gas is a hydrocarbon gas or a hydrocarbon gas and an oxygen-containing gas, A mixture of at least one of nitrogen-containing gas, boron-containing gas, and phosphorus-containing gas.