A microwave plasma chemical vapor deposition device in the millimeter-wave band

Abstract

The application relates to a microwave plasma chemical vapor deposition device in a millimeter wave frequency band, and belongs to the technical field of chemical vapor deposition.The microwave plasma chemical vapor deposition device comprises a microwave source, a beam splitter, a phase-shifting module and a vacuum cavity.The microwave source is used for generating a beam in a millimeter wave frequency band.The beam splitter is used for converting the beam in the millimeter wave frequency band into a plurality of sub-beams with the same amplitude and phase distribution.The phase-shifting module is filled with ferrite inside and is used for adjusting the phase of the sub-beams.The vacuum cavity is internally provided with a sample table used for placing a sample.The sub-beams after phase adjustment are synthesized on the sample.The application realizes the rapid adjustment of the phase of the beam through the phase-shifting module, realizes the rapid change of the positions of the wave crest and the wave trough of the synthesized standing wave field, and solves the problem of the uniformity of the standing wave field in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of chemical vapor deposition technology, and more specifically relates to a microwave plasma chemical vapor deposition device in the millimeter-wave band. Background Technology

[0002] Microwave plasma chemical vapor deposition (MPCVD) is a novel technology that has emerged in recent years for the preparation of high-quality carbon materials. It has advantages such as high deposition quality, large deposition area, and stable deposition process. To increase the deposition rate in MPCVD devices, some studies have increased the operating frequency of MPCVD devices to the millimeter-wave band to increase the electron density in the plasma sphere, thereby accelerating the deposition rate of functional groups in the device.

[0003] Existing millimeter-wave MPCVD devices are based on millimeter-wave quasi-optical theory. They achieve large-area, stable plasma distribution by superimposing multiple beams to synthesize a standing wave field through a millimeter-wave quasi-optical transmission system. However, the standing wave field formed by multiple beams is not uniformly distributed due to the presence of troughs and antinodes. To improve the uniformity of this distribution, existing devices often consider rotating the sample stage or using more beams for synthesis. However, both adding a rotation mechanism within the vacuum cavity and using more beams for synthesis significantly increase the cost and size of the device.

[0004] Therefore, the existing technology needs further improvement. Summary of the Invention

[0005] To address the shortcomings of existing technologies and solve the aforementioned problems, a microwave plasma chemical vapor deposition device in the millimeter-wave band is proposed. By using a phase-shifting module to achieve rapid adjustment of the beam phase, the device enables rapid changes in the positions of antinodes and troughs of the synthesized standing wave field, thereby solving the problem of standing wave field uniformity in existing technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A microwave plasma chemical vapor deposition apparatus in the millimeter-wave band, comprising:

[0008] Microwave source, used to generate beams in the millimeter-wave band;

[0009] A beam splitter is used to convert a millimeter-wave band beam into multiple sub-beams with the same amplitude and phase distribution.

[0010] The phase-shifting module, which is filled with ferrite, is used to adjust the phase of the sub-beam;

[0011] It also includes a vacuum chamber, inside which is a sample stage for placing the sample, and the phase-adjusted sub-beams are combined onto the sample.

[0012] This technical solution is further configured to include a corrugated waveguide, which is located between the microwave source and the beam splitter. The millimeter-wave band beam is transmitted in the corrugated waveguide in a HE (High-Earth) configuration. 11 model.

[0013] The technical solution is further configured such that the phase-shifting module sequentially includes a first polarization conversion section, a phase-shifting section, and a second polarization conversion section. Both the first polarization conversion section and the second polarization conversion section generate a transverse magnetic field to adjust the polarization of the sub-beam, and the phase-shifting section adjusts the phase of the sub-beam.

[0014] The technical solution is further configured such that the first polarization conversion section includes a magnetic ring and a first ferrite, the first ferrite is embedded inside the magnetic ring, and a transverse magnetic field is generated inside the magnetic ring.

[0015] The technical solution is further configured such that the second polarization conversion segment has the same structure as the first polarization conversion segment, and both generate the same transverse magnetic field inside.

[0016] The technical solution is further configured such that the phase-shifting segment includes an excitation coil and a second ferrite, the second ferrite being embedded inside the excitation coil, and the excitation coil being connected to the phase-shifting power supply.

[0017] This technical solution is further configured such that by adjusting the output current of the phase-shifting power supply, the current in the excitation coil is changed, and the permeability of the second ferrite is controlled to change the propagation constant, thereby achieving sub-beam phase adjustment.

[0018] The technical solution is further configured such that a microwave window is provided on the vacuum cavity, and the phase shifting module is located inside or outside the microwave window, with the inner side of the microwave window located inside the vacuum cavity.

[0019] The technical solution is further configured such that there are multiple microwave windows, and the number of microwave windows, the number of phase shifting modules, and the number of sub-beams are equal.

[0020] The technical solution is further configured such that the microwave window is a window formed of a microwave-transparent material.

[0021] The beneficial effects of this invention are:

[0022] By adjusting the phase of the sub-beams using a phase-shifting module, the positions of the antinodes and troughs of the standing wave field synthesized by the sub-beam superposition are moved, resulting in a more uniform distribution of the synthesized electromagnetic waves. This allows for the acquisition of a larger and more uniform plasma, avoiding the need to increase the volume of the vacuum cavity or the number of sub-beam paths. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the microwave plasma chemical vapor deposition apparatus in the millimeter-wave band used in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the phase-shifting module used in Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the microwave plasma chemical vapor deposition apparatus in the millimeter-wave band used in Embodiment 2 of the present invention;

[0026] Figure 4 This is a schematic diagram of the microwave plasma chemical vapor deposition apparatus in the millimeter-wave band used in Embodiment 3 of the present invention.

[0027] In the attached diagram: 1-corrugated waveguide, 2-beam splitter, 3-phase shifting module, 4-vacuum cavity, 5-sample stage, 6-first reflecting mirror, 7-second reflecting mirror, 8-third reflecting mirror, 9-first polarization conversion section, 10-phase shifting section, 11-second polarization conversion section, 12-magnetic ring, 13-first ferrite, 14-excitation coil, 15-second ferrite, 16-microwave window. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0029] Example 1:

[0030] like Figure 1 As shown, a microwave plasma chemical vapor deposition device in the millimeter-wave band includes a microwave source, a beam splitter 2, a phase shifting module 3, and a vacuum cavity 4.

[0031] The technical solution is further configured such that the microwave source is used to generate a beam in the millimeter-wave frequency band, which can be a conventional microwave generator or other equipment in the art; the beam splitter 2 is used to convert the beam in the millimeter-wave frequency band into multiple sub-beams with the same amplitude and phase distribution; the phase shifting module 3 is filled with ferrite to adjust the phase of the sub-beams; the vacuum cavity 4 is provided with a sample stage 5 for placing the sample, and the sub-beams after phase adjustment are combined on the sample.

[0032] It should be noted that by adjusting the phase of the sub-beams through the phase-shifting module 3, the positions of the antinodes and troughs of the standing wave field synthesized by the sub-beam superposition are moved, making the distribution of the synthesized electromagnetic waves more uniform, so as to obtain a larger range and more uniform plasma, and avoid increasing the volume of the vacuum cavity 4 or the number of sub-beam paths.

[0033] Specifically, the vacuum chamber 4 provides the gas atmosphere and pressure required to maintain chemical vapor deposition, and the sample stage 5 is the region where the chemical vapor deposition reaction occurs, as well as the region where sub-beams are superimposed and synthesized.

[0034] This technical solution is further configured to include a corrugated waveguide 1, which is located between the microwave source and the beam splitter 2. The millimeter-wave band beam is transmitted in the corrugated waveguide 1 in a HE (high-frequency) manner. 11 model.

[0035] It should be noted that the function of corrugated waveguide 1 is to receive the millimeter-wave frequency band beam output from a high-power microwave source and couple it into a quasi-HE beam. 11 The pattern is used for dissemination.

[0036] This technical solution is further configured such that the beam splitter 2 is an overmode corrugated waveguide, the function of which is to split the single quasi-HE beam at the entrance. 11 The mode beam is converted into multiple sub-beams with the same amplitude and phase distribution.

[0037] like Figure 2 As shown, the phase-shifting module 3 sequentially includes a first polarization conversion section 9, a phase-shifting section 10, and a second polarization conversion section 11. Both the first polarization conversion section 9 and the second polarization conversion section 11 generate transverse magnetic fields to adjust the polarization of the sub-beams, and the phase-shifting section 10 adjusts the phase of the sub-beams.

[0038] This technical solution is further configured such that the first polarization conversion section 9 includes a magnetic ring 12 and a first ferrite 13, the first ferrite 13 being embedded inside the magnetic ring 12, and a transverse magnetic field being generated inside the magnetic ring 12. Preferably, the magnetic ring 12 is a permanent magnet.

[0039] It should be noted that the first polarization conversion section 9 utilizes the birefringence effect of the first ferrite 13 to convert the sub-wave beam from a linearly polarized wave to a circularly polarized wave under the action of an external transverse magnetic field.

[0040] The technical solution is further configured such that the second polarization conversion segment 11 has the same structure as the first polarization conversion segment 9, and both generate the same transverse magnetic field inside.

[0041] It should be noted that the second polarization conversion section 11 utilizes the birefringence effect of the first ferrite to convert the sub-wave beam from a circularly polarized wave back to a linearly polarized wave under the action of an external transverse magnetic field.

[0042] The technical solution is further configured such that the phase-shifting segment 10 includes an excitation coil 14 and a second ferrite 15, the second ferrite 15 being embedded inside the excitation coil 14, and the excitation coil 14 being connected to the phase-shifting power supply.

[0043] It should be noted that the phase shifting segment 10 utilizes the Faraday rotation effect of the second ferrite 15 to adjust the output current of the phase shifting power supply, thereby changing the current in the excitation coil 14 and controlling the permeability of the second ferrite 15 to change the propagation constant, thus achieving sub-beam phase adjustment.

[0044] In other words, the magnetic rings in the first polarization conversion section 9 and the second polarization conversion section 11 are used to generate the transverse magnetic field required for the birefringence effect, and the excitation coil 14 is used to rapidly change the current magnitude to achieve rapid adjustment of the sub-beam phase.

[0045] The technical solution is further configured such that a microwave window 16 is provided on the vacuum cavity 4, and the phase shifting module 3 is located outside the microwave window 16, with the outside of the microwave window 16 located outside the vacuum cavity 4.

[0046] It should be noted that the microwave window 16 is the window through which the sub-beam enters the vacuum cavity 4, and it is made of a wave-transparent material, such as boron nitride or sapphire.

[0047] This technical solution is further configured such that multiple microwave windows 16 are provided, and the number of microwave windows 16, the number of phase shifting modules 3, and the number of sub-beams are equal. Preferably, the multiple microwave windows 16 are symmetrically arranged around the sample stage 5.

[0048] It should be noted that the millimeter-wave band beam is converted into multiple sub-beams with the same amplitude and phase distribution by the beam splitter 2. Each sub-beam is equipped with a phase shifting module 3 and a microwave window 16 on its transmission path.

[0049] In this embodiment, the millimeter-wave band beam is converted into two sub-beams with the same amplitude and phase distribution by the beam splitter 2. Correspondingly, two phase-shifting modules 3 and two microwave windows 16 are provided. Specifically, a first reflector 6 and a second reflector 7 are parallel to each other on the outside of the vacuum cavity 4, and a third reflector 8 is provided on the inside of the vacuum cavity 4. The second reflector 7 and the third reflector 8 are both positioned corresponding to the microwave window 16. The phase-adjusted sub-beams are transmitted to the third reflector 8 via the first reflector 6, the second reflector 7, and the microwave window 16, and after changing their transmission direction, they are transmitted to the sample stage 5. That is to say, the function of the first reflector 6, the second reflector 7, and the third reflector 8 is to transform, propagate, and synthesize the beam output by the phase-shifting module 3 to meet the electric field distribution and coverage required by the MPCVD device.

[0050] Example 2:

[0051] like Figure 2 As shown, the parts that are the same as those in Embodiment 1 will not be repeated here. The differences are as follows:

[0052] The phase-shifting module 3 is located outside the microwave window 16. Specifically, the phase-shifting module 3 is located between the first reflector 6 and the second reflector 7.

[0053] A microwave source generates a millimeter-wave frequency beam, which is transmitted to a beam splitter 2 through a corrugated waveguide 1. The millimeter-wave frequency beam is converted into two sub-beams with the same amplitude and phase distribution by the beam splitter 2. The sub-beams are transmitted to a phase-shifting module 3 through a first reflector 6. The phase-adjusted sub-beams are transmitted to a third reflector 8 through a second reflector 7 and a microwave window 16. After changing the transmission direction, they are transmitted to a sample stage 5.

[0054] Example 3:

[0055] like Figure 3 As shown, the parts that are the same as those in Embodiment 1 will not be repeated here. The differences are as follows:

[0056] The phase-shifting module 3 is located inside the microwave window 16. Specifically, the phase-shifting module 3 is located between the second reflector 7 and the third reflector 8.

[0057] A microwave source generates a millimeter-wave frequency beam, which is transmitted to a beam splitter 2 via a corrugated waveguide 1. The millimeter-wave frequency beam is converted into two sub-beams with the same amplitude and phase distribution by the beam splitter 2. The sub-beams are transmitted to the phase shifting module 3 via the first reflector 6, the second reflector 7, and the microwave window 16. After the phase is adjusted, the sub-beams are transmitted to the sample stage 5 after the transmission direction is changed by the third reflector 8.

[0058] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of this application should still fall within the scope of the present invention.

Claims

1. A microwave plasma chemical vapor deposition apparatus for millimeter wave band, characterized by, The application relates to a microwave source for generating a beam in a millimeter wave frequency band, a beam splitter for converting the beam in the millimeter wave frequency band into a plurality of sub-beams with the same amplitude and phase distribution, a phase-shifting module filled with ferrite for adjusting the phase of the sub-beams, the phase-shifting module comprising a first polarization conversion section, a phase-shifting section and a second polarization conversion section in sequence, the first polarization conversion section comprising a magnetic ring and a first ferrite embedded in the interior of the magnetic ring, the interior of the magnetic ring generating a transverse magnetic field, the first polarization conversion section converting the sub-beam from linearly polarized wave into circularly polarized wave by using the birefringence effect of the first ferrite under the action of the external transverse magnetic field, the second polarization conversion section being the same in structure as the first polarization conversion section, the second polarization conversion section converting the sub-beam from circularly polarized wave back into linearly polarized wave by using the birefringence effect of the first ferrite under the action of the external transverse magnetic field, the phase-shifting section comprising an excitation coil and a second ferrite embedded in the interior of the excitation coil, the excitation coil being connected with a phase-shifting power source, the phase-shifting section using the Faraday rotation effect of the second ferrite to change the magnetic permeability of the second ferrite by adjusting the output current of the phase-shifting power source, changing the current size in the excitation coil and controlling the propagation constant to realize phase adjustment of the sub-beam, and a vacuum cavity provided with a sample table for placing a sample, wherein the phase-adjusted sub-beams are synthesized on the sample. The vacuum cavity is provided with a microwave window, and the phase-shifting module is located on the inner side or the outer side of the microwave window, and the inner side of the microwave window is located in the interior of the vacuum cavity. The microwave window is provided with a plurality of microwave windows, and the number of the microwave windows, the number of the phase-shifting modules and the number of the sub-beams are equal. The microwave window is a window formed by a wave-transparent material. ​ 2. The microwave plasma chemical vapor deposition apparatus for millimeter wave band according to claim 1, wherein Also included is a corrugated waveguide located between the microwave source and the beam splitter, the transmission of the beam in the millimeter wave frequency band in the corrugated waveguide being HE 11 mode.

3. The microwave plasma chemical vapor deposition apparatus for millimeter wave band according to claim 1 or 2, characterized by ​ 4. The microwave plasma chemical vapor deposition apparatus of claim 3, wherein ​ 5. The microwave plasma chemical vapor deposition apparatus of claim 3, wherein ​

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