MPCVD cylindrical reactor based on distributed antenna array structure

Abstract

The invention discloses an MPCVD cylindrical reactor based on a distributed antenna array structure, and relates to the field of microwave plasma chemical vapor deposition. The reactor comprises a power divider and a distributed antenna array multi-port cavity; the power divider is arranged at the upper end of the distributed antenna array multi-port cavity and is connected with the distributed antenna array multi-port cavity through a cavity port outer conductor; the power divider is used for uniformly distributing an input microwave signal to obtain a plurality of same sub-microwave signals; and the distributed antenna array multi-port cavity adopts a cylindrical structure and is used for receiving a plurality of same sub-microwave signals and exciting a fixed TM electromagnetic mode in a discharge area. The microwave energy utilization efficiency is effectively improved.

Description

Technical Field

[0001] This application relates to the field of microwave plasma chemical vapor deposition, and in particular to an MPCVD cylindrical reactor based on a distributed antenna array structure. Background Technology

[0002] Currently, the feeding method for microwave plasma chemical vapor deposition (MPCVD) reactors used for diamond growth is almost always microwaves that excite the TM0mn electromagnetic mode in a cylindrical or dish-shaped reactor via a waveguide-coaxial converter [1]. Some linear multi-source MPCVD reactors and distributed antenna array reactors have also been reported, but the resonant mode inside the cavity is not fixed. The multi-source MPCVD device based on the microwave resonant cavity structure (patent CN 117457465 A) is not a distributed antenna array structure. The multi-source MPCVD reactor based on the distributed antenna array structure (patent CN 113088938 B) is a dish structure rather than a cylindrical one, and it cannot guarantee the high power reflection problem of plasma load to the excitation port under operating conditions. Summary of the Invention

[0003] The purpose of this application is to provide an MPCVD cylindrical reactor based on a distributed antenna array structure, which can effectively improve the microwave energy utilization efficiency by impedance matching between the multi-port MPCVD reactor and the plasma load end based on the distributed antenna array.

[0004] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides an MPCVD cylindrical reactor based on a distributed antenna array structure, the reactor comprising: Power dividers and distributed antenna array multi-port cavities; The power divider is located at the top of the multi-port cavity of the distributed antenna array and is connected through the external conductor of the cavity port. A power divider is used to evenly distribute an input microwave signal into multiple identical sub-microwave signals. The distributed antenna array multi-port cavity adopts a cylindrical structure to receive multiple identical sub-microwave signals and excite a fixed TM electromagnetic mode in the discharge region.

[0005] Furthermore, the power divider also includes: The rectangular waveguide port, waveguide-coaxial transition structure, coaxial inner conductor, and power divider output antenna are connected in sequence. The outer conductor of the coaxial line is positioned outside the inner conductor of the coaxial line. The rectangular waveguide port, waveguide-coaxial transition structure, and coaxial inner conductor are used to transmit the input microwave signal to the power divider output antenna. The antenna at the output of the power divider is used to evenly distribute the received microwave signal into multiple identical sub-microwave signals.

[0006] Furthermore, the distributed antenna array multi-port cavity also includes: Inner conductor antenna, circular ring structure quartz dielectric window, process support device, observation window; The inner conductor antennas are arranged at equal intervals on the quartz dielectric window of the ring structure; The upper end of the inner conductor antenna is connected to the outer conductor of the cavity port, and the lower end of the inner conductor antenna extends to the process support device. A circular quartz dielectric window is used to isolate the inner conductor antenna from the process carrier device; A process support device used to form the reaction chamber of the discharge region.

[0007] Furthermore, the process support device also includes: The copper support, primary metal, secondary metal, copper pillar, and deposition stage are connected in sequence.

[0008] Furthermore, the observation window also includes: The observation window is embedded in the side wall of the process support device, and multiple windows are set at equal intervals.

[0009] Furthermore, the outer conductor of the cavity port also includes: One end of the outer conductor at the cavity port is connected to the output antenna of the power divider via a screw structure, and the other end is connected to the inner conductor antenna via a screw structure.

[0010] According to the specific embodiments provided in this application, this application has the following technical effects: Impedance matching between the multi-port MPCVD reactor based on a distributed antenna array and the plasma load is achieved, effectively improving microwave energy utilization efficiency.

[0011] The PTFE or ceramic insulating material filling the space between the inner and outer conductors of the cavity port ensures the insulation and mechanical stability of the feed structure, avoids short circuits or signal crosstalk, and further improves the reliability of microwave transmission. The power divider output antenna precisely distributes 12 equal-amplitude and in-phase signals, providing accurate energy input assurance for the formation of stable electromagnetic modes within the cavity.

[0012] The 12 inner conductor antennas are arranged at equal intervals, and with the input of equal amplitude and in phase signals, the uniformity of the electromagnetic field distribution in the cavity is enhanced, ensuring the stability of plasma discharge. The quartz medium window is fixed by a slot, which not only effectively isolates the microwave transmission area from the process area, ensuring the sealing and purity of the process environment, but also does not attenuate microwave energy, ensuring efficient energy penetration. The outer conductor of the cavity port is connected to the antenna at the output end of the power divider and the inner conductor antenna by detachable screws, which enables convenient replacement of the inner conductor antenna and reduces the difficulty of tuning operation. By replacing the inner conductor antenna with one of different lengths, impedance matching between the cavity port and the plasma load can be precisely achieved, specifically addressing the defect of high reflected power in existing multi-port MPCVD reactors and reducing microwave energy waste. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a structural diagram of an MPCVD cylindrical reactor based on a distributed antenna array structure according to one embodiment of this application; Figure 2 The electric field distribution diagram of the power divider connection cavity; Figure 3 This is a diagram showing the connection structure between the power divider and the cavity. Figure 4 Electric field distribution diagram comparing efficiency with antenna length; Figure 5 S-parameter plot showing the relationship between efficiency and antenna length; Among them, 1 is a rectangular waveguide port; 2 is a waveguide-coaxial transition structure; 3 is a coaxial inner conductor; 4 is a power divider output antenna; 5 is a coaxial outer conductor; 6 is a cavity port outer conductor; 7 is an inner conductor antenna; 8 is a quartz dielectric window; 9 is an observation window; 10 is a copper support; 11 is a primary metal; 12 is a secondary metal; 13 is a deposition stage; and 14 is a copper pillar. Detailed Implementation

[0015] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] A cylindrical MPCVD reactor based on a distributed antenna array structure, the reactor comprising: The power divider is located at the upper end of the multi-port cavity of the distributed antenna array and is connected to the multi-port cavity of the distributed antenna array through the outer conductor 6 of the cavity port. The power divider is an integrated structure used to evenly distribute the input microwave signal into 12 equal-amplitude and in-phase sub-microwave signals. The multi-port cavity of the distributed antenna array adopts an integrated cylindrical structure to receive the 12 equal-amplitude and in-phase sub-microwave signals and excite a fixed TM electromagnetic mode in the discharge region inside the cavity.

[0018] Optionally, the power divider may also include: The coaxial outer conductor 5 is coaxially sleeved outside the coaxial inner conductor 3, and the cavity port outer conductor 6 and the inner conductor are filled with PTFE or ceramic insulating material; the rectangular waveguide port 1, the waveguide-coaxial transition structure 2 and the coaxial inner conductor 3 sequentially conduct the input microwave signal, and finally transmit it to the power divider output antenna 4; the power divider output antenna 4 is used to distribute the received microwave signal into 12 equal amplitude and in phase sub-microwave signals to achieve uniform distribution of microwave energy.

[0019] Ensure that the power signals from the rectangular port of the microwave output to the output ports of the 12 power dividers are of equal amplitude and in phase. Table 1

[0020] Therefore, a stable TM mode can be excited in the discharge region within the cavity, such as Figure 3 As shown, the colors represent the strength of the electric field. The red area indicates the region with a stronger electric field in the cavity state, i.e., the region where plasma is easily excited. Yellow, green, and blue represent decreasing electric fields in that order.

[0021] Optionally, the distributed antenna array multi-port cavity further includes: Twelve inner conductor antennas 7 are arranged at equal intervals above the quartz dielectric window 8 of the ring structure, corresponding one-to-one with the twelve output terminals of the power divider. The upper end of the inner conductor antenna 7 is connected to the outer conductor 6 of the cavity port, and the lower end extends into the discharge area inside the cavity. The inner conductor antenna 7 has a detachable screw structure, and its length can be replaced in the range of 32mm-72mm. The quartz dielectric window 8 of the ring structure is fixed by a 5mm upper and lower slot in the cavity, which is used to isolate the microwave transmission area where the inner conductor antenna 7 is located from the process area where the process carrier device is located, while allowing microwave signals to penetrate. The process carrier device is located inside the multi-port cavity of the distributed antenna array and is used to form a closed discharge area for plasma reaction.

[0022] The distributed antenna array multi-port cavity is an integrated structure with quartz dielectric windows 8 and 5mm upper and lower slots.

[0023] A process support device used to form the reaction chamber of the discharge region.

[0024] Optionally, the process support device may also include: The process support device includes a copper support 10, a primary metal step 11, a secondary metal step 12, a copper pillar 14, and a deposition stage 13, which are rigidly connected in sequence. The copper support 10 is horizontally fixed in a preset installation position inside the multi-port cavity of the distributed antenna array. The upper end of the primary metal step 11 is connected to the copper support 10, and the lower end is connected to the upper end of the secondary metal step 12. The lower end of the secondary metal step 12 is fixed to the upper end of the copper pillar 14, and the lower end of the copper pillar 14 is connected to the deposition stage 13. The deposition stage 13 is a molybdenum support.

[0025] Optionally, viewing window 9 also includes: Among them, the observation window 9 is embedded in the side wall of the process support device, and multiple windows are set at equal intervals.

[0026] Optionally, the cavity port outer conductor 6 also includes: One end of the outer conductor 6 of the cavity port is detachably connected to the output antenna 4 of the power divider via a screw structure, and the other end is detachably connected to the inner conductor antenna 7 via a screw structure. By replacing the inner conductor antenna 7 with different lengths, impedance matching between the cavity port and the plasma load can be achieved.

[0027] The connection structure between the power divider and the cavity is as follows: Figure 4 As shown, the antenna 4 at the output end of the power divider and the antenna at the feed cavity end have screw structures inside, which can be unscrewed and replaced with different lengths for tuning the cavity port and the plasma load end.

[0028] When the length of the inner conductor antenna 7 is adjusted to 52mm, the input reflection coefficient under plasma load can reach -29dB, and the microwave energy utilization efficiency exceeds 99%. Within the range of 32mm-72mm in length of the inner conductor antenna 7, the microwave energy utilization efficiency is always greater than 90%, and the TM electromagnetic mode in the cavity remains fixed.

[0029] By simultaneously changing the lengths of the 12 inner conductor antennas 7 in the feed cavity, the input reflection coefficient can be calculated by measuring the incident and reflected power of the system using a power meter. The optimal input reflection coefficient under plasma load can reach -29dB (when the length is 52mm), at which point the microwave energy utilization efficiency exceeds 99%. At the same time, the electromagnetic mode within the cavity remains fixed at any length, and the efficiency can always be greater than 90% within a certain length range.

[0030] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0031] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (Read-Only Memory). Memory includes ROM, magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0032] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0033] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0034] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A cylindrical MPCVD reactor based on a distributed antenna array structure, characterized in that, The reactor includes: Power divider, cavity port outer conductor, and multi-port cavity for distributed antenna array; The power divider is located at the top of the multi-port cavity of the distributed antenna array and is connected through the external conductor of the cavity port. A power divider is used to evenly distribute an input microwave signal into multiple identical sub-microwave signals. The distributed antenna array multi-port cavity adopts a cylindrical structure to receive multiple identical sub-microwave signals and excite a fixed TM electromagnetic mode in the discharge region.

2. The MPCVD cylindrical reactor based on a distributed antenna array structure according to claim 1, characterized in that, It also includes a power divider: The rectangular waveguide port, waveguide-coaxial transition structure, coaxial inner conductor, and power divider output antenna are connected in sequence. The outer conductor of the coaxial line is positioned outside the inner conductor of the coaxial line. The rectangular waveguide port, waveguide-coaxial transition structure, and coaxial inner conductor are used to transmit the input microwave signal to the power divider output antenna. The antenna at the output of the power divider is used to evenly distribute the received microwave signal into multiple identical sub-microwave signals.

3. The MPCVD cylindrical reactor based on a distributed antenna array structure according to claim 1, characterized in that, The distributed antenna array multi-port cavity also includes: Inner conductor antenna, circular ring structure quartz dielectric window, process support device, observation window; The inner conductor antennas are arranged at equal intervals on the quartz dielectric window of the ring structure; The upper end of the inner conductor antenna is connected to the outer conductor of the cavity port, and the lower end of the inner conductor antenna extends to the process support device. A circular quartz dielectric window is used to isolate the inner conductor antenna from the process carrier device; A process support device used to form the reaction chamber of the discharge region.

4. The MPCVD cylindrical reactor based on a distributed antenna array structure according to claim 1, characterized in that, The process support device also includes: The copper support, primary metal, secondary metal, copper pillar, and deposition stage are connected in sequence.

5. The MPCVD cylindrical reactor based on a distributed antenna array structure according to claim 1, characterized in that, Observation window, also include: The observation window is embedded in the side wall of the process support device, and multiple windows are set at equal intervals.

6. The MPCVD cylindrical reactor based on a distributed antenna array structure according to claim 1, characterized in that, The outer conductor of the cavity port also includes: One end of the outer conductor at the cavity port is connected to the output antenna of the power divider via a screw structure, and the other end is connected to the inner conductor antenna via a screw structure.

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