A multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface

Abstract

The present invention discloses a multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface, which solves the technical problem that the existing resonant cavity structure limits the low power and slow growth rate of diamond synthesis. The present invention includes a microwave generating device for microwave emission, and a growth cavity connected to the microwave generating device for diamond synthesis; an annular quartz window is provided in the growth cavity, a water-cooled copper table antenna is provided above the annular quartz window, a threaded molybdenum table for placing diamond crystals is provided above the water-cooled copper table antenna, a plasma is provided above the threaded molybdenum table, and a conical reflective surface is provided on the top surface of the growth cavity. The present invention has a simple structure, a scientific and reasonable design, and is easy to use. It can greatly enhance the microwave power, improve the growth rate, and greatly reduce the silicon pollution caused by plasma etching.

Description

Technical Field

[0001] The invention belongs to the technical field of diamond processing, and in particular relates to a multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface. Background Art

[0002] Today, diamond has been widely used in defense, industry, science and technology, medical and health fields. It has excellent properties that other materials cannot match, making it one of the best all-round materials in the world today, playing an irreplaceable role in many industrial fields. However, natural diamond reserves are small, mining is difficult, and the quality is unstable, which cannot meet the needs of the industrial field or even the consumer field.

[0003] MPCVD synthetic diamond is a new method for preparing high-quality diamond developed in the 1980s. The microwave discharge area is concentrated and does not diverge, so the contamination of the epitaxial diamond film caused by electrode discharge and cavity wall is avoided. The emergence of MPCVD synthetic diamond technology has successfully solved the problems of pollution and diamond growth size.

[0004] At present, the diamond single crystal material prepared by the MPCVD method has almost achieved all the characteristics of natural diamond. Therefore, the MPCVD method is currently the most commonly used method for synthesizing high-quality diamond. However, the commonly used MPCVD power is 6kw or even less, which is mainly due to the structure of the microwave resonant cavity. Larger microwave power will enhance the etching effect of the plasma, resulting in the etching of the quartz window. The etched silicon atoms will grow into the interior of the diamond, reducing the performance of the diamond. At the same time, this type of cavity is small in size and close to the plasma, so it is easy to form deposits on the cavity wall. After long-term use, the peeling of the deposits will cause impurity contamination on the surface of the diamond. Although reducing the power can avoid the occurrence of the above situation, it also has obvious disadvantages, such as low synthesis efficiency, slow growth rate, and small deposition area.

[0005] Therefore, the present invention provides a multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface, which solves the technical problems of low diamond synthesis power and slow growth rate limited by the existing resonant cavity structure, can greatly enhance microwave power, increase growth rate, and greatly reduce silicon contamination caused by plasma etching. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface to solve the technical problem that the existing resonant cavity structure limits the low diamond synthesis power and slow growth rate.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A multimode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface comprises a microwave generating device for emitting microwaves, and a growth cavity connected to the microwave generating device for diamond synthesis; an annular quartz window, a water-cooled copper table antenna located above the annular quartz window, a threaded molybdenum table located above the water-cooled copper table antenna for placing diamond crystals, and a plasma located above the threaded molybdenum table are arranged in the growth cavity, and a conical reflective surface is arranged on the top surface of the growth cavity.

[0009] Furthermore, the conical reflecting surface is located directly above the plasma.

[0010] Furthermore, a vacuum chamber is provided between the conical reflection surface and the growth cavity.

[0011] Furthermore, an air inlet channel is provided in the vacuum chamber, and an air inlet pipe is provided in the air inlet channel. One end of the air inlet pipe is connected to a gas cylinder storing process gas outside, and the other end is connected to the growth cavity.

[0012] Furthermore, an observation window is provided on the side wall of the growth chamber for conveniently observing the internal plasma morphology and diamond growth conditions.

[0013] Furthermore, there are two observation windows, which are symmetrically distributed with respect to the growth cavity.

[0014] Furthermore, the observation window is sealed with high temperature resistant glass.

[0015] Furthermore, the microwave generating device includes a microwave head, a circulator connected to the microwave head, a waveguide connected to the circulator, and a mode converter respectively connected to the waveguide and the growth cavity.

[0016] Furthermore, three pins are provided in the waveguide for achieving impedance matching.

[0017] Furthermore, a coaxial line and a short-circuit piston for achieving impedance matching are provided in the mode converter.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The invention has a simple structure, a scientific and reasonable design, and is easy to use. It solves the technical problems of low diamond synthesis power and slow growth rate limited by the existing resonant cavity structure, can greatly enhance microwave power, increase growth rate, and can also greatly reduce silicon pollution caused by plasma etching.

[0020] The present invention includes a microwave generator and a growth cavity, wherein the microwave generator is used for emitting microwaves, and the growth cavity is used for synthetic growth of diamonds. An annular quartz window is provided in the growth cavity, a water-cooled copper antenna is provided above the annular quartz window, a threaded molybdenum platform is provided above the water-cooled copper antenna, a plasma is provided above the threaded molybdenum platform, and a conical reflecting surface is provided on the top surface of the growth cavity. The microwaves emitted by the microwave generator are input from the bottom of the growth cavity, which is completed by the annular water-cooled copper antenna, and the annular quartz window is provided below the water-cooled copper antenna, so that the annular quartz window is hidden below the deposited threaded molybdenum platform, so that the annular quartz window is away from the plasma, and the silicon contamination caused by the etching of the annular quartz window by hydrogen plasma is avoided. The conical reflecting surface on the top surface of the growth cavity can effectively gather energy directly below the conical reflecting surface, greatly improve the input microwave power and improve the synthetic efficiency of diamond; at the same time, the increase in power can effectively increase the deposition area, so that the deposition area is increased from the original 2 inches to 4 inches. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention.

[0022] The names corresponding to the reference numerals are:

[0023] 1-growth chamber, 2-annular quartz window, 3-water-cooled copper antenna, 4-plasma, 5-conical reflecting surface, 6-vacuum chamber, 7-inlet channel, 8-inlet pipe, 9-observation window, 10-microwave head, 11-circulator, 12-waveguide, 13-mode converter, 14-three pins, 15-coaxial line, 16-short-circuit piston. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore they cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; of course, it can also be a mechanical connection or an electrical connection; in addition, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] like Figure 1 As shown, the present invention provides a multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface, which has a simple structure, scientific and reasonable design, and is easy to use. It solves the technical problems of low diamond synthesis power and slow growth rate limited by the existing resonant cavity structure, can greatly enhance microwave power, increase growth rate, and greatly reduce silicon pollution caused by plasma etching.

[0028] The present invention comprises a microwave generator for emitting microwaves, and a growth cavity 1 connected to the microwave generator for diamond synthesis; an annular quartz window 2 is arranged in the growth cavity 1, a water-cooled copper antenna 3 is arranged above the annular quartz window 2, a threaded molybdenum platform for placing diamond crystals is arranged above the water-cooled copper antenna 3, a plasma 4 is arranged above the threaded molybdenum platform, and a conical reflecting surface 5 is arranged on the top surface of the growth cavity 1. The microwave emitted by the microwave generator is input from the bottom of the growth cavity 1, which is completed by the annular water-cooled copper antenna 3, and the annular quartz window 2 is arranged below the water-cooled copper antenna 3, so that the annular quartz window 3 is hidden below the deposited threaded molybdenum platform, and the annular quartz window 3 is kept away from the plasma 4, so as to avoid the silicon contamination and other problems caused by the annular quartz window 3 being etched by hydrogen plasma, and the annular quartz window 3 also plays the role of vacuum sealing and microwave transmission channel. The conical reflecting surface 5 on the top surface of the growth cavity 1 is located directly above the plasma 4, which can effectively gather energy directly below the conical reflecting surface 5, greatly improving the input microwave power, which can reach 15kw-20kw, thereby improving the synthesis efficiency of diamond; at the same time, the increase in power can effectively increase the deposition area, increasing the deposition area from the original 2 inches to 4 inches.

[0029] A vacuum chamber 6 is provided between the conical reflective surface 5 and the growth chamber 1 of the present invention. An air inlet channel 7 is provided in the vacuum chamber 6, and an air inlet pipe 8 is provided in the air inlet channel 7. One end of the air inlet pipe 8 is connected to a gas cylinder storing process gas outside, and the other end is connected to the growth chamber 1. The process gas is introduced from the air inlet pipe 8 at the center of the growth chamber 1, which can better increase the uniformity of deposition.

[0030] The side wall of the growth chamber 1 of the present invention is provided with an observation window 9. There are two observation windows 9, which are symmetrically distributed about the growth chamber 1. High temperature resistant glass is sealed on the observation window 9. The observation window 9 is convenient for observing the internal plasma 4 morphology and diamond growth conditions, as well as temperature measurement operations.

[0031] The microwave generating device of the present invention comprises a microwave head 10, a circulator 11 connected to the microwave head 10, a waveguide tube 12 connected to the circulator 11, and a mode converter 13 respectively connected to the waveguide tube 12 and the growth cavity 1. A three-pin 14 for achieving impedance matching is arranged in the waveguide tube 12. A coaxial line 15 and a short-circuit piston 16 for achieving impedance matching are arranged in the mode converter 13. The microwave generated by the microwave head 10 is output to the waveguide tube 12 through the circulator 11, and the coaxial line 15 transmits the microwave energy to the growth cavity 1 through the mode converter 13, and excites plasma for diamond growth under appropriate gas pressure and microwave power matching. The circulator 11 has a one-way passing function, and can absorb the microwave reflected from the growth cavity 1 with a water load, prevent the reflected microwave from entering the magnetron, and avoid damage to the magnetron. The three pins 14 and the short-circuit piston 16 can be used to adjust the impedance matching under different powers and gas pressures, so that the microwave energy is fed into the growth cavity 1 as much as possible, reducing the loss of microwaves.

[0032] The microwave head 10, circulator 11, waveguide tube 12, three pins 14, coaxial line 15 and short-circuit piston 16 used in the present invention are all existing known electrical equipment and can be directly purchased and used on the market. Their structures, circuits, and control principles are all existing known technologies. Therefore, the structures, circuits, and control principles of the microwave head 10, circulator 11, waveguide tube 12, three pins 14, coaxial line 15 and short-circuit piston 16 are not described in detail here.

[0033] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or modifications made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface, characterized in that: The invention comprises a microwave generating device for emitting microwaves, and a growth cavity (1) connected to the microwave generating device for diamond synthesis; the growth cavity (1) is provided with an annular quartz window (2), a water-cooled copper table antenna (3) located above the annular quartz window (2), a threaded molybdenum table located above the water-cooled copper table antenna (3) for placing diamond crystals, and a plasma (4) located above the threaded molybdenum table; and the top surface of the growth cavity (1) is provided with a conical reflection surface (5); A vacuum chamber (6) is provided between the conical reflection surface (5) and the growth chamber (1); The conical reflecting surface (5) is located directly above the plasma (4).

2. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 1, characterized in that: An air inlet channel (7) is provided in the vacuum chamber (6), and an air inlet pipe (8) is provided in the air inlet channel (7). One end of the air inlet pipe (8) is connected to a gas cylinder storing process gas outside, and the other end is connected to the growth chamber (1).

3. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 1, characterized in that: An observation window (9) is provided on the side wall of the growth chamber (1) for conveniently observing the morphology of the internal plasma (4) and the diamond growth condition.

4. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 3, characterized in that: There are two observation windows (9), which are symmetrically distributed with respect to the growth chamber (1).

5. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 3, characterized in that: The observation window (9) is sealed with high temperature resistant glass.

6. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 1, characterized in that: The microwave generating device comprises a microwave head (10), a circulator (11) connected to the microwave head (10), a waveguide tube (12) connected to the circulator (11), and a mode converter (13) respectively connected to the waveguide tube (12) and the growth cavity (1).

7. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 6, characterized in that: Three pins (14) for achieving impedance matching are arranged in the waveguide tube (12).

8. The multi-mode non-cylindrical resonant cavity MPCVD device with a conical reflective top surface according to claim 6, characterized in that: A coaxial line (15) and a short-circuit piston (16) for achieving impedance matching are provided in the mode converter (13).

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