Combined MPCVD resonant cavity and MPCVD equipment
By designing a combined MPCVD resonant cavity, the problem of insufficient flexibility in existing equipment is solved, adaptability to different growth processes is achieved, deposition efficiency and uniformity are improved, and equipment costs are reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-03-10
AI Technical Summary
The resonant cavity design of existing MPCVD deposition equipment is integrated, which has poor flexibility and makes it difficult to meet the needs of diamond deposition size and process diversity.
A modular MPCVD resonant cavity was designed, comprising a fixed cavity top and bottom structure, and various sizes of replaceable intermediate cavity wall bodies. These are connected in a detachable manner and sealed using seals, supporting the replacement of cavity wall bodies of different shapes and sizes, and are suitable for diamond deposition in different growth processes.
It improves the flexibility and deposition efficiency of MPCVD deposition equipment, reduces costs, facilitates vacuum maintenance and water cooling pipeline layout, enables precise control of the electric field distribution in the deposition area, and improves deposition uniformity and rate.
Smart Images
Figure CN223983728U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of microwave plasma chemical deposition technology, and in particular to a combined MPCVD resonant cavity and MPCVD equipment. Background Technology
[0002] Microwave plasma chemical vapor deposition (MPCVD) is an important technology for preparing high-quality diamond materials. It decomposes chemical vapor substances under low pressure and high temperature conditions and deposits them on a substrate under microwave electric field excitation. It has the advantages of high efficiency, uniformity and controllability. MPCVD technology is widely used in materials science, surface engineering, electronic devices and optical devices.
[0003] Currently, most MPCVD deposition equipment uses an integrated resonant cavity design. While this design is easy to implement, it is difficult to meet the requirements of diamond deposition size and process diversity, resulting in poor flexibility in use. Utility Model Content
[0004] The purpose of this application is to address one of the aforementioned technical deficiencies by providing a combined MPCVD resonant cavity and MPCVD equipment, with a replaceable cavity wall body for the MPCVD resonant cavity, suitable for diamond deposition requirements of different growth processes.
[0005] A combined MPCVD resonant cavity includes: a cavity top and a cavity bottom with a fixed structure design, and a replaceable intermediate cavity wall body of various specifications;
[0006] An air inlet is fixedly provided on the top of the cavity;
[0007] The bottom of the cavity is fixedly provided with a microwave feed inlet, a deposition platform and a gas outlet;
[0008] The intermediate cavity wall body has a cavity wall structure of a predetermined shape, and sealing elements are respectively provided on the upper and lower surfaces of the intermediate cavity wall body;
[0009] The top of the cavity is connected to the bottom of the cavity;
[0010] Each of the intermediate cavity wall bodies is detachably connected between the top and bottom of the cavity, and is sealed to the top and bottom of the cavity by the sealing member.
[0011] In one embodiment, the top of the cavity is further provided with an observation window and a temperature measuring window; the deposition platform is connected to the bottom of the cavity through a quartz window.
[0012] In one embodiment, the upper and lower surfaces of the intermediate cavity wall body are provided with slots for accommodating the sealing element.
[0013] In one embodiment, the sealing element is a rubber ring; the top and bottom of the cavity are sealed by squeezing the rubber ring when they are fixedly connected.
[0014] In one embodiment, the top and bottom of the cavity are respectively provided with multiple bolt holes for fixed connection by mounting bolts of a set length;
[0015] The intermediate cavity wall body includes: a cavity wall structure of a predetermined size and a plurality of connecting parts connected to the cavity wall structure; wherein, one end of the connecting part is connected to the cavity wall structure and the other end is provided with a through hole;
[0016] During installation, the intermediate cavity wall body is stacked on top of the cavity and bottom of the cavity so that the bolt holes and through holes correspond. After the screw of the installation bolt passes through the bolt hole and the through hole, it is fixed with a nut. The intermediate cavity wall body is then installed between the top and bottom of the cavity.
[0017] In one embodiment, the intermediate cavity wall body includes: a cavity wall structure of a predetermined size and an upper joint and a lower joint of uniform size; wherein the upper joint and the lower joint are respectively connected to the upper and lower ends of the cavity wall structure;
[0018] The upper and lower joints respectively match the edges of the top and bottom of the cavity;
[0019] During installation, the upper and lower joints of the intermediate cavity wall body are placed corresponding to the top and bottom of the cavity, respectively, and the edges of the top and bottom of the cavity are fixedly connected by clamps.
[0020] In one embodiment, the intermediate cavity wall body includes: a cavity wall structure of a predetermined size and a rectangular outer shell of a uniform size; wherein the cavity wall structure is embedded within the rectangular outer shell;
[0021] The upper and lower edges of the rectangular shell are provided with grooves;
[0022] The upper and lower edges of the rectangular shell are provided with grooves;
[0023] The three edges at the top of the cavity are bent inward to form a first bend, and the three edges at the bottom of the cavity are bent inward to form a second bend. The first bend and the second bend respectively match the groove.
[0024] During installation, the groove of the intermediate cavity wall body is fitted into the first bent part at the top of the cavity and the second bent part at the bottom of the cavity, so that the intermediate cavity wall body is fixedly connected to the top and bottom of the cavity respectively.
[0025] In one embodiment, the intermediate cavity wall body includes a cavity wall structure of a predetermined size;
[0026] The top and bottom of the cavity are fixedly connected by three side panels; the three side panels are provided with screw holes for passing through fixing bolts.
[0027] During installation, the cavity wall structure is embedded in the space between the top and bottom of the cavity, and the cavity wall structure is fixed by rotating the fixing bolts.
[0028] In one embodiment, the cross-section of the cavity wall structure is circular, square, or rounded rectangle.
[0029] An MPCVD device includes: a microwave source and the aforementioned combined MPCVD resonant cavity;
[0030] The microwave source feeds microwaves into the MPCVD resonant cavity through the microwave feed inlet.
[0031] The technical solution of the above embodiments is based on the design of a combined MPCVD resonant cavity. It designs a variety of replaceable MPCVD resonant cavity body in various specifications. During use, the cavity body with the best matching degree can be adopted according to the deposition requirements, which is suitable for the deposition requirements of diamonds with different growth processes and improves the deposition flexibility.
[0032] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description
[0033] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
[0034] Figure 1 This is a schematic diagram of a combined MPCVD resonant cavity structure according to one embodiment;
[0035] Figure 2 This is a schematic diagram of the cross-section of an example combined MPCVD resonant cavity;
[0036] Figure 3 This is a schematic diagram of microwave field superposition in an example circular cavity deposition region;
[0037] Figure 4 This is a schematic diagram of microwave field superposition in a square cavity deposition region, as an example.
[0038] Figure 5 This is a schematic diagram of the structure of an example intermediate cavity wall body;
[0039] Figure 6 This is a schematic diagram of an example combined MPCVD resonant cavity installation;
[0040] Figure 7 This is a schematic diagram of the structure of the main body of the intermediate cavity wall in another example;
[0041] Figure 8 Here is another example of a combined MPCVD resonant cavity mounting schematic diagram;
[0042] Figure 9 This is yet another example of a structural schematic diagram of the main body of the intermediate cavity wall.
[0043] Figure 10 This is yet another example of a combined MPCVD resonant cavity installation diagram;
[0044] Figure 11 Here is another example of a combined MPCVD resonant cavity installation diagram;
[0045] Figure 12 This is a schematic diagram of the structure of an MPCVD device according to one embodiment. Detailed Implementation
[0046] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0047] Those skilled in the art will understand that, unless otherwise stated, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in this application’s specification means the presence of the stated feature, integer, step, or operation, but does not preclude the presence or addition of one or more other features, integers, steps, or operations.
[0048] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.
[0049] refer to Figure 1 As shown, Figure 1 This is a schematic diagram of a combined MPCVD resonant cavity structure according to one embodiment. Its overall structure is square, including: a fixed cavity top 01 and cavity bottom 02, and various sizes of replaceable intermediate cavity wall bodies 03. The parameters of the different sizes mainly include differences in shape, size, and height; for example... Figure 2 As shown, Figure 2 This is a schematic diagram of the cross-section of an example combined MPCVD resonant cavity, wherein an air inlet 11 is fixedly provided on the top 01 of the cavity, and a microwave feed inlet 21, a deposition stage 22 and an air outlet are fixedly provided on the bottom 02 of the cavity; furthermore, an observation window 12 and a temperature measuring window 13 can also be provided on the top 01 of the cavity, and the deposition stage 22 can be connected to the bottom 02 of the cavity through a quartz window 221.
[0050] The intermediate cavity wall body 03 has a cavity wall structure 31 with a predetermined shape, and a sealing element 30 is provided on the upper and lower surfaces of the intermediate cavity wall body 03 respectively; for example, the cavity wall structure 31 can be designed as a circle, square or rounded rectangle, etc.; further, a slot 30a can be provided on the upper and lower surfaces of the intermediate cavity wall body 03 to accommodate the sealing element 30; for example, the sealing element 30 can be a rubber ring, which can be embedded into the slot 30a.
[0051] In use, the top 01 of the cavity is fixedly connected to the bottom 02 of the cavity; each intermediate cavity wall body 03 is detachably connected between the top 01 of the cavity and the bottom 02 of the cavity, and is sealed to the top 01 of the cavity and the bottom 02 of the cavity by a sealing member 30; as in the above embodiment, a rubber ring is used for sealing, and the top 01 of the cavity and the bottom 02 of the cavity are sealed by squeezing the rubber ring when they are fixedly connected, forming a vacuum cavity.
[0052] In the above embodiment, an MPCVD resonant cavity design with replaceable accessories is provided. The top 01 and bottom 02 of the cavity are fixed structures, while the main body 03 of the middle cavity wall is a replaceable structure design. This allows for replacement according to the corresponding microwave field distribution to meet different growth requirements, thereby greatly improving the flexibility of the MPCVD deposition equipment and reducing costs at the same time. It also facilitates the maintenance of the vacuum level inside the cavity and the arrangement of water cooling pipes.
[0053] In the above embodiment, when the cross-section of the cavity wall structure 31 is circular, the corresponding cavity wall structure 31 can achieve the superposition of TM021 and TM011 microwave modes in the deposition region, such as... Figure 3 As shown, Figure 3 This is a schematic diagram of microwave field superposition in an example circular cavity deposition area. Under this structure, the microwave focusing capability is strong, making it suitable for the deposition of small-area diamonds.
[0054] In the above embodiment, when the cross-section of the cavity wall structure 31 is square, the corresponding cavity wall structure 31 can achieve the superposition of TM021, TM031, and TM011 microwave modes in the deposition region, such as... Figure 4 As shown, Figure 4 This is a schematic diagram of a microwave field superposition in a square cavity deposition region. This structure offers strong microwave field adjustability, making it suitable for large-area diamond deposition with high uniformity requirements. Furthermore, by changing the dimensions of the square cavity walls, different electric field intensities and uniformities can be created in the deposition region, making diamond deposition more flexible. And because it differs from cylindrical microwave superposition modes, the top (01) of the cavity is less prone to forming secondary strong field regions and plasma excitation, making it suitable for higher-power deposition as well.
[0055] For example, by using an electromagnetic simulation program, different structures and sizes (such as structure: circular, square; size: diameter, side length, height) of the cavity wall structure 31 can be adopted according to the electric field distribution of the deposition area suitable for different needs and processes. The MPCVD cavity equipment can achieve more flexible and convenient diamond deposition by replacing different cavity wall structures 31.
[0056] Regarding the selection of dimensions, the shape of the cavity wall structure 31 can be determined first based on actual process requirements, and then the diameter or side length of the cavity wall structure 31 can be determined based on the distribution effect of TM021 and the superposition strength of TM021 and TM031; taking a microwave frequency of 2.45GHz as an example: the microwave wavelength is If TM021 is selected as the microwave distribution mode, the diameter range of the cavity wall structure 31 is approximately The specific dimensions depend on the intensity and uniformity of the microwave field distribution in the actual deposition area. If the actual diamond deposition area is small, it is necessary to increase the intensity of the microwave field distribution in the deposition area, so a smaller diameter or side length should be selected within the range. If the actual diamond deposition area is large and the requirement for deposition uniformity is high, it is necessary to increase the uniformity of the microwave field distribution in the deposition area, so a larger diameter or side length should be selected within the range.
[0057] Furthermore, after determining the selected shape and diameter or side length, the height of the intermediate cavity wall body 03 is then determined so that the resonant cavity can achieve optimal coupling efficiency at the operating frequency of the microwave source 04, and ensures that the eigenfrequency of the selected resonant cavity's eigenmode is consistent with the operating frequency of the microwave source 04, i.e. .
[0058] For example, to enhance flexibility, other line structures can be added to the cavity wall structure 31 based on actual simulation results. For instance, rounded corners can be added to a square to form a rounded rectangle, and straight edges can be added to a circular cavity structure. This provides more flexible options for the shape changes of the main body 03 of the intermediate cavity wall, so as to achieve better matching results.
[0059] In one embodiment, to avoid errors between simulation and actual use, the replaceable MPCVD cavity structure can be combined with a liftable stage to increase the tuning structure, which can more accurately control the excitation of plasma during the actual growth process.
[0060] To make the technical solution of this application clearer, more embodiments of the structure of the combined MPCVD resonant cavity are provided below with reference to the accompanying drawings.
[0061] In one embodiment, the combined MPCVD resonant cavity of this application, such as Figure 5 As shown, Figure 5 This is a schematic diagram of the structure of an example intermediate cavity wall body 03. The intermediate cavity wall body 03 includes: a cavity wall structure 31 of a set size and a plurality of connecting parts 32 connected to the cavity wall structure 31; wherein, one end of the connecting part 32 is connected to the cavity wall structure 31, and the other end is provided with a through hole 32b; the top 01 and bottom 02 of the cavity body are respectively provided with a plurality of bolt holes for fixing by mounting bolts 23 of a set length. Four different cavity wall structures 31 are shown in the figure. Among them, Figure (a) and Figure (b) are square shapes with different side lengths, and Figure (c) and Figure (d) are circular shapes with different diameters.
[0062] During installation, such as Figure 6 As shown, Figure 6 This is a schematic diagram of the installation of a combined MPCVD resonant cavity. The intermediate cavity wall body 03 is stacked with the top cavity 01 and the bottom cavity 02 so that the bolt holes correspond to the through holes 32b. After the screw of the mounting bolt 23 is passed through the bolt holes and the through holes 32b, it is fixed with nuts. The intermediate cavity wall body 03 is installed between the top cavity 01 and the bottom cavity 02.
[0063] As in the above embodiments, the replaceable intermediate cavity wall body 03 has a simple structure and the overall MPCVD resonant cavity has a low cost.
[0064] In one embodiment, the combined MPCVD resonant cavity of this application, such as Figure 7 As shown, Figure 7This is a schematic diagram of the structure of another example of the intermediate cavity wall body; the intermediate cavity wall body 03 includes: a cavity wall structure 31 of a set size and an upper joint 331 and a lower joint 332 of uniform size; wherein, the upper joint 331 and the lower joint 332 are respectively connected to the upper and lower ends of the cavity wall structure 31; the upper joint 331 and the lower joint 332 are respectively matched with the edges of the top 01 and the bottom 02 of the cavity; the figure shows two cavity wall structures 31 with different shapes, wherein, Figure (e) is a rounded rectangular shape design and Figure (f) is a square shape design.
[0065] During installation, such as Figure 8 As shown, Figure 8 This is another example of a combined MPCVD resonant cavity installation diagram; the upper joint 331 and lower joint 332 of the middle cavity wall body 03 are placed corresponding to the top 01 and bottom 02 of the cavity, respectively, and the edges of the top 01 and bottom 02 of the cavity are fixedly connected by clamps 33c.
[0066] As described in the above embodiments, the replaceable intermediate cavity wall body 03 has a simple structure and is easy to install. The replaceable intermediate cavity wall body 03 is easy to install and disassemble, and the overall MPCVD resonant cavity cost is also low.
[0067] In one embodiment, the combined MPCVD resonant cavity of this application, such as Figure 9 As shown, Figure 9 This is another example of a schematic diagram of the structure of the intermediate cavity wall body 03; the intermediate cavity wall body 03 includes: a cavity wall structure 31 of a predetermined size and a rectangular outer shell 34 of a uniform size; wherein, the cavity wall structure 31 is embedded in the rectangular outer shell 34; the upper and lower edges of the rectangular outer shell 34 are provided with grooves 34d; the figure shows two cavity wall structures 31 with different shapes, wherein, figure (g) is a square shape design and figure (h) is a circular shape design. The three edges of the top 01 of the cavity are bent inward to form a first bent portion 10a, and the three edges of the bottom 02 of the cavity are bent inward to form a second bent portion 20a. The first bent portion 10a and the second bent portion 20a respectively match the grooves 34d.
[0068] During installation, such as Figure 10 As shown, Figure 10 This is another example of a combined MPCVD resonant cavity installation diagram; the groove 34d of the intermediate cavity wall body 03 is fitted into the first bent part 10a of the top of the cavity 01 and the second bent part 20a of the bottom of the cavity 02, so that the intermediate cavity wall body 03 is fixedly connected to the top of the cavity 01 and the bottom of the cavity 02 respectively.
[0069] As described in the above embodiments, the replaceable intermediate cavity wall body 03 is particularly easy to install and remove, making it especially suitable for applications where rapid replacement of the intermediate cavity wall body 03 is required, thus greatly improving deposition efficiency.
[0070] In one embodiment, the combined MPCVD resonant cavity of this application has an intermediate cavity wall body 03 including a cavity wall structure 31 of a set size; the top 01 and bottom 02 of the cavity are fixedly connected by three side panels 102; wherein, the three side panels 102 are provided with screw holes for passing through fixing bolts 301.
[0071] During installation, such as Figure 11 As shown, Figure 11 Here is another example of a combined MPCVD resonant cavity installation diagram; the cavity wall structure 31 is embedded in the space between the top 01 and the bottom 02 of the cavity, and the cavity wall structure 31 is fixed by rotating the fixing bolt 301.
[0072] As described in the above embodiments, the replaceable intermediate cavity wall body 03 has a simple structure and low cost. It can be configured in large quantities with intermediate cavity wall bodies 03 of various specifications, sizes and shapes to meet various diamond deposition requirements.
[0073] The following describes an embodiment of the MPCVD equipment.
[0074] This application provides an MPCVD device, with reference to... Figure 12 As shown, Figure 12 This is a schematic diagram of an MPCVD device structure according to one embodiment, including a microwave source 04 and a combined MPCVD resonant cavity of any of the above embodiments; wherein, the microwave source 04 feeds microwaves into the MPCVD resonant cavity through the microwave feed inlet 21.
[0075] The MPCVD equipment of this application, through the chamber design with replaceable accessories, realizes a variety of replaceable MPCVD equipment with low equipment processing and use costs, and can realize the deposition of different growth processes to meet various diamond needs.
[0076] The technical solutions described in the above embodiments can achieve precise control of the electric field distribution in the deposition region, resulting in a more uniform electric field distribution and a more concentrated electric field excitation, thereby improving the deposition rate, material quality, and deposition uniformity under limited microwave power.
[0077] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.
Claims
1. A combined MPCVD resonant cavity, characterized in that, The utility model relates to a microwave cavity structure, including: The cavity top (1) and the cavity bottom (2) of fixed structure design and the replaceable middle cavity wall main part (3) of multiple specifications; The cavity top (1) is fixed with the air inlet (11); The cavity bottom (2) is fixed with the microwave feed inlet (21), the deposition base (22) and the air outlet; The middle cavity wall main part (3) has the cavity wall structure (31) of setting shape, and the upper and lower surfaces of middle cavity wall main part (3) are equipped with sealing element (30) respectively; The cavity top (1) is connected with the cavity bottom (2); Each middle cavity wall main part (3) is connected between the cavity top (1) and the cavity bottom (2) by detachable mode, and is sealedly connected with the cavity top (1) and the cavity bottom (2) through the sealing element (30).
2. The combined MPCVD resonant cavity of claim 1, wherein, The cavity top (1) is also provided with an observation window (12) and a temperature measurement window (13); the deposition base (22) is connected to the cavity bottom (2) through a quartz window (221).
3. The combined MPCVD resonant cavity of claim 1, wherein, The upper and lower surfaces of the middle cavity wall main part (3) are provided with clamping grooves (30a) for accommodating the sealing element (30).
4. The combined MPCVD resonant cavity of claim 3, wherein, The sealing element (30) is a rubber ring; the cavity top (1) and the cavity bottom (2) are fixedly connected by extruding the rubber ring to realize cavity sealing.
5. The combined MPCVD resonant cavity of claim 3, wherein, The cavity top (1) and the cavity bottom (2) are respectively provided with a plurality of bolt holes corresponding to each other for fixed connection through installation bolts (23) of a set length; The middle cavity wall main part (3) includes a cavity wall structure (31) of a set size and a plurality of connecting parts (32) connected to the cavity wall structure (31); one end of the connecting part (32) is connected to the cavity wall structure (31), and the other end is provided with a through hole (32b); During installation, the middle cavity wall main part (3) is placed in superposition with the cavity top (1) and the cavity bottom (2) so that the bolt holes correspond to the through holes (32b), the shank of the installation bolt (23) is inserted through the bolt holes and the through holes (32b), and then the middle cavity wall main part (3) is fixed by a nut, and the middle cavity wall main part (3) is installed between the cavity top (1) and the cavity bottom (2).
6. The combined MPCVD resonant cavity of claim 3, wherein, The middle cavity wall main part (3) includes a cavity wall structure (31) of a set size and upper and lower joint parts (331) and (332) of a uniform size; the upper and lower joint parts (331) and (332) are respectively connected to the upper and lower ends of the cavity wall structure (31); The upper and lower joint parts (331) and (332) respectively match the edges of the cavity top (1) and the cavity bottom (2); During installation, the upper and lower joint parts (331) and (332) of the middle cavity wall main part (3) are placed corresponding to the cavity top (1) and the cavity bottom (2), and the edges of the cavity top (1) and the cavity bottom (2) are fixedly connected by a clamp (33c).
7. The combined MPCVD resonant cavity of claim 3, wherein, The intermediate cavity wall body (03) comprises a cavity wall structure (31) of a certain size and a rectangular shell (34) of a uniform size; wherein the cavity wall structure (31) is embedded in the rectangular shell (34); The upper edge and the lower edge of the rectangular shell (34) are provided with grooves (34d); Three edges of the cavity top (01) are respectively inwardly bent to form first bending portions (10a), and three edges of the cavity bottom (02) are respectively inwardly bent to form second bending portions (20a); the first bending portions (10a) and the second bending portions (20a) are respectively matched with the grooves (34d); During installation, the grooves (34d) of the intermediate cavity wall body (03) are sleeved into the first bending portions (10a) of the cavity top (01) and the second bending portions (20a) of the cavity bottom (02), so that the intermediate cavity wall body (03) is fixedly connected with the cavity top (01) and the cavity bottom (02) respectively.
8. The combined MPCVD resonant cavity of claim 3, wherein, The intermediate cavity wall body (03) comprises a cavity wall structure (31) of a certain size; The cavity top (01) and the cavity bottom (02) are fixedly connected through three side panels (102); wherein the three side panels (102) are provided with screw holes for passing through fixed bolts (301); During installation, the cavity wall structure (31) is embedded in the space between the cavity top (01) and the cavity bottom (02), and the cavity wall structure (31) is fixed by rotating the fixed bolts (301).
9. The combined MPCVD resonant cavity of claim 5, wherein, The cross section of the cavity wall structure (31) is circular, square or round rectangular.
10. An MPCVD apparatus, characterized by, It comprises: a microwave source (04) and the combined MPCVD resonant cavity body of any one of claims 1-9; The microwave source (04) feeds microwaves into the MPCVD resonant cavity body through the microwave feeding inlet (21).