Plasma reaction chamber and microwave plasma chemical vapor deposition device

Abstract

The present invention provides a plasma reaction chamber and a microwave plasma chemical vapor deposition device. The plasma reaction chamber comprises a vacuum chamber, the vacuum chamber comprises a pedestal structure extending into the chamber from the outside, and a microwave window is arranged at a position, above the pedestal structure, of the top of the vacuum chamber and used for allowing microwaves to enter the vacuum chamber to excite reaction gas in a reaction area; the vacuum chamber comprises a first flow homogenization ring, the first flow homogenization ring is arranged at the top of the vacuum chamber and surrounds the microwave window, and a first gas flow channel is arranged in the first flow homogenization ring, wherein a plurality of first gas outlet holes communicated with the first gas flow channel are formed in the first flow homogenization ring, the first gas flow channel supplies oxygen-enriched gas into the vacuum chamber by means of the first gas outlet holes, the orientation of the plurality of first gas outlet holes is arranged to enable the oxygen-enriched gas sprayed from the first gas outlet holes to form an oxygen-enriched area on the surface of the microwave window, and the oxygen content in the oxygen-enriched area is higher than that in the reaction area.

Description

Plasma reaction chamber and microwave plasma chemical vapor deposition device Technical Field

[0001] The present invention relates to the field of plasma technology, in particular to a plasma reaction chamber and a microwave plasma chemical vapor deposition device. Background Art

[0002] Microwave plasma chemical vapor deposition (MPCVD) equipment generally includes a microwave system, a vacuum system, a gas supply system and a plasma reaction chamber. Taking the preparation of diamond film as an example, the microwaves generated by the microwave system enter the plasma reaction chamber, and excite the gas provided by the gas supply system above the substrate stage in the plasma reaction chamber to generate a plasma ball. The plasma ball is deposited on the surface of the film-forming substrate material to form a diamond film.

[0003] During a plasma reaction, such as when forming a diamond film, reactive gases such as methane and hydrogen decompose into various active radicals under the action of the plasma, which then deposit onto the substrate surface to form a diamond film. During this process, due to the excitation, activation, diffusion, and deposition of gases within the vacuum reaction chamber, some solid deposits also accumulate on the microwave window surface. Furthermore, as deposition time increases, the thickness of the deposits increases, and eventually they may fracture due to internal stress. The resulting fragments can fall onto the substrate surface, forming contaminants and affecting normal diamond growth. Summary of the Invention

[0004] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides a plasma reaction chamber and a microwave plasma chemical vapor deposition device, which can etch solid deposits deposited on the surface of the microwave window during the plasma reaction process, inhibit the formation of solid deposits in the surface area of ​​the microwave window, and thus reduce the contamination of the microwave window surface by solid deposits during the plasma reaction.

[0006] Specifically, the above-mentioned plasma reaction chamber provided according to the first aspect of the present invention includes: a vacuum chamber, the vacuum chamber includes a base structure extending into the cavity from the outside, and the top of the vacuum chamber is provided with a microwave window above the base structure, which is used to allow microwaves to enter the vacuum chamber and excite the reaction gas in the reaction area; the vacuum chamber includes a first equalizing flow ring, which is arranged at the top of the vacuum chamber and surrounds the microwave window, and a first airflow channel is provided inside the first equalizing flow ring, wherein the first equalizing flow ring is provided with a plurality of first air outlet holes connected to the first airflow channel, and the first airflow channel supplies oxygen-rich gas to the vacuum chamber through the first air outlet holes, and the orientation of the plurality of first air outlet holes is set so that the oxygen-rich gas ejected from the first air outlet holes forms an oxygen-rich area on the lower surface of the microwave window, and the oxygen content in the oxygen-rich area is higher than that in the reaction area.

[0007] Preferably, in one embodiment of the present invention, a second airflow channel isolated from the first airflow channel is provided inside the first flow balancing ring, and a plurality of second air outlet holes connected to the second airflow channel are provided for supplying reaction gas to the reaction area in the vacuum chamber.

[0008] Preferably, in an embodiment of the present invention, the vacuum chamber further comprises a second flow balancing ring, and the second flow balancing ring is provided with a plurality of third gas outlet holes for supplying reaction gas to the reaction area in the vacuum chamber.

[0009] Preferably, in an embodiment of the present invention, the orientation of the plurality of first air outlet holes is set to be toward the center position of the microwave window.

[0010] Preferably, in an embodiment of the present invention, the first current equalizing ring is arranged along the lower edge of the microwave window and closely attached to the lower surface of the microwave window.

[0011] Preferably, in an embodiment of the present invention, the plurality of first air outlet holes are distributed in a centrally symmetrical manner.

[0012] Preferably, in one embodiment of the present invention, the oxygen-rich gas is a gas containing oxygen and / or carbon monoxide.

[0013] Preferably, in one embodiment of the present invention, the oxygen-rich gas is pure oxygen, which is used to remove carbon deposits on the lower surface of the microwave window.

[0014] Preferably, in one embodiment of the present invention, the sum of the oxygen content in the oxygen-rich region and the oxygen content in the reaction region constitutes the oxygen content required for growing diamond.

[0015] In addition, the microwave plasma chemical vapor deposition apparatus provided according to the second aspect of the present invention includes a microwave system, a vacuum system, a gas supply system, and the plasma reaction chamber provided by any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or characteristics may have the same or similar reference numerals.

[0017] FIG1 shows a schematic diagram of a microwave plasma chemical vapor deposition apparatus according to some embodiments of the present invention;

[0018] FIG2 shows a partial schematic diagram of a plasma reaction chamber according to some embodiments of the present invention; and

[0019] FIG3 shows a schematic diagram of a first current balancing ring provided according to some embodiments of the present invention. Attached photos

[0020] 100 Microwave plasma chemical vapor deposition equipment;

[0021] 110 plasma reaction chamber;

[0022] 111, 212 abutment structure;

[0023] 112 diamond;

[0024] 113, 210, 320 microwave windows;

[0025] 114 metal cover;

[0026] 115, 310 first current equalizing ring;

[0027] 120 microwave systems;

[0028] 130 Vacuum system;

[0029] 211 Non-diamond carbon deposition;

[0030] 220 oxygen-rich areas;

[0031] 230 reaction area;

[0032] 330 vacuum sealing ring;

[0033] 341, 342 air intake ducts; and

[0034] A, B orientation. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Note that the various aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0037] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood to refer to the orientations depicted in that section and the accompanying drawings. These relative terms are used solely for convenience of description and do not necessarily imply that the devices described herein must be manufactured or operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0038] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various components, regions, layers, and / or portions, these components, regions, layers, and / or portions should not be limited by these terms, and these terms are merely used to distinguish different components, regions, layers, and / or portions. Thus, a first component, region, layer, and / or portion discussed below may be referred to as a second component, region, layer, and / or portion without departing from some embodiments of the present invention.

[0039] As mentioned above, during a plasma reaction, such as when forming a diamond film, reactant gases such as methane and hydrogen decompose into various reactive radicals under the action of the plasma, which then deposit onto the substrate table to form a diamond film. During this process, due to the excitation, activation, diffusion, and deposition of gases within the vacuum reaction chamber, some solid deposits also accumulate on the microwave window surface. Furthermore, as deposition time increases, the thickness of the deposits increases, and eventually they may fracture due to internal stress. The resulting fragments can fall onto the substrate table surface, forming contaminants and affecting normal diamond growth.

[0040] In order to overcome the above-mentioned defects of the prior art, the present invention provides a plasma reaction chamber and a microwave plasma chemical vapor deposition device, which can etch solid deposits deposited on the surface of the microwave window during the plasma reaction process, inhibit the formation of solid deposits in the surface area of ​​the microwave window, and thus reduce the contamination of the microwave window surface by solid deposits during the plasma reaction.

[0041] Please refer to FIG1 , which shows a schematic diagram of a microwave plasma chemical vapor deposition apparatus according to some embodiments of the present invention.

[0042] As shown in Figure 1, a microwave plasma chemical vapor deposition apparatus 100 includes a plasma reaction chamber 110, a microwave system 120, a vacuum system 130, and a gas supply system (not shown). The plasma reaction chamber 110 may include a vacuum chamber, and a base structure 111 extends from the outside of the vacuum chamber into the vacuum chamber. The substrate table surface of the base structure 111 can be used to grow diamond 112. The base structure 111 can be located at the central axis of the plasma reaction chamber 110.

[0043] A microwave window 113 is disposed above the base structure 111. Located at the top of the vacuum chamber, microwaves emitted by the microwave system 120 are allowed to enter the vacuum chamber. As shown in FIG1 , the microwave window 113 and a metal cover 114 together form the top of the vacuum chamber. In another non-limiting embodiment, the microwave window 113 can be directly embedded in the top inner wall of the vacuum chamber.

[0044] In the embodiment shown in FIG1 , the vacuum chamber may further include a first current balancing ring 115 , which is disposed at the top of the vacuum chamber surrounding the microwave window 113 , and a first airflow channel (not shown in the figure) is disposed inside the first current balancing ring 115 .

[0045] Please refer to FIG. 2 , which shows a partial schematic diagram of a plasma reaction chamber provided according to some embodiments of the present invention.

[0046] As shown in FIG2 , below the microwave window 210 is the interior of the vacuum chamber of the plasma reaction chamber. Non-diamond carbon deposition 211 has formed on the lower surface of the microwave window 210 during the plasma reaction process. The non-diamond carbon deposition 211 will contaminate the microwave window 210 .

[0047] The gas supply system introduces oxygen-rich gas into a first airflow channel provided in the first flow-balancing ring. The oxygen-rich gas is ejected through a first gas outlet connected to the first airflow channel, forming an oxygen-rich region 220 on the surface of the microwave window 210. The oxygen-rich gas contained in this oxygen-rich region 220 reacts with the non-diamond carbon deposits 211 on the surface of the microwave window 210 to form carbon dioxide (CO2) (CO2 is one of the raw materials used for diamond growth). This effectively etches the non-diamond carbon deposits 211 deposited on the lower surface of the microwave window 210 while also suppressing the formation of new non-diamond carbon deposits.

[0048] Here, the orientation of the plurality of first gas outlet holes can be set so that the oxygen-rich gas ejected from the first gas outlet holes forms an oxygen-rich region 220 on the surface of the microwave window 210. Preferably, the first current equalizing ring can be arranged along the lower edge of the microwave window 210, closely adjacent to the lower surface of the microwave window 210, and conforming to the shape of the microwave window 210. The orientation of the plurality of first gas outlet holes can be set to be centrally symmetrically distributed on the first current equalizing ring and can be set to face the center of the microwave window 210.

[0049] In other embodiments, those skilled in the art may also, based on the above concepts, adaptively configure the first current balancing ring and its multiple first air outlets to similarly form an oxygen-rich region on the surface of the microwave window. Optionally, multiple rows of first air outlets may be distributed around the inner ring of the first current balancing ring, and these first air outlets may be oriented obliquely upward.

[0050] 2 , microwaves can enter the vacuum chamber through microwave window 210 and excite the reaction gas in reaction region 230 above base structure 212, thereby growing diamond on the base surface of base structure 212. Here, the oxygen content in oxygen-rich region 220 is higher than that in reaction region 230.

[0051] In a reference example, due to the presence of a plasma ball in the reaction region above the base structure, the energy density in this region is greater than that of the microwave window surface region, where oxygen-rich region 220 in Figure 2 is located. Therefore, in this region, the carbon source gas (e.g., methane) in the introduced reaction gas reacts more efficiently, making it more suitable for diamond growth. In contrast, in the microwave window surface region, due to the relatively lower energy density, the decomposition efficiency is also lower. In this situation, the carbon source gas in the reaction gas is more likely to form a non-diamond carbon film on the microwave window surface. Although the non-diamond carbon film is also carbon, its arrangement structure differs from that of diamond carbon. The adhesion of the non-diamond carbon film to the microwave window surface can cause the window to darken, affecting light transmission. Furthermore, when the non-diamond carbon film reaches a certain thickness, it can randomly fall off and mix into the growing diamond, contaminating the normal diamond growth.

[0052] Therefore, in the embodiment shown in FIG. 2 , the plasma reaction chamber can etch the non-diamond carbon film deposited on the surface of the microwave window 210 by introducing oxygen-rich gas into the oxygen-rich region 220 and inhibit the growth of the non-diamond carbon film in the oxygen-rich region 220 .

[0053] Furthermore, during the plasma reaction, excessively high oxygen concentrations in the raw gas components within the plasma reaction chamber can reduce the diamond growth rate. Therefore, in a preferred embodiment, without changing the overall composition of the raw gas within the reaction chamber, the reaction gas and oxygen-rich gas are introduced into the plasma reaction chamber through separate inlet lines. The oxygen in the oxygen-rich gas reacts with the non-diamond carbon and is completely converted into the raw gas CO2. The raw gas within the reaction chamber is formed through the reaction of the oxygen-rich gas with the non-diamond carbon and the mixing of the reaction gas and the oxygen-rich gas. The oxygen content in the reaction chamber is then combined with the oxygen content in the reaction zone to provide the oxygen content required for diamond growth. The oxygen-rich gas can be an oxygen-containing gas containing oxygen and / or carbon monoxide that can further react with carbon (e.g., oxygen-rich gas formed by directly adding oxygen and / or carbon monoxide to the reaction gas), or it can be pure oxygen, which is used to react with the non-diamond carbon on the microwave window surface.

[0054] For example, in the embodiment shown in FIG2 , 1.5 sccm of pure oxygen can be separated from a flow rate of 3.0 sccm (standard cubic centimeter per minute) of oxygen as an oxygen-enriched gas and sprayed onto the oxygen-enriched region 220 on the surface of the microwave window 210. The remaining 1.5 sccm of oxygen is mixed with methane (CH4) and hydrogen (H2) to form a reaction gas, which is then introduced into the reaction region 230. The oxygen reacts with the non-diamond carbon film to form CO2, while the methane and hydrogen react with the oxygen to form a reaction gas, which together form a raw material gas with a gas composition of CH4 / H2 / CO2 for diamond growth.

[0055] In a reference example, the gas supply system directly introduced a feed gas composed of CH4 / H2 / CO2 into the plasma reaction chamber. Eighty hours after the plasma reaction began, the microwave window darkened due to the formation of a non-diamond carbon film. By 120 hours, the microwave window was essentially impermeable to visible light. In contrast, in the aforementioned embodiment, microwave window 210 only began to slightly darken due to the deposition of non-diamond carbon after 150 hours of plasma reaction. Therefore, by introducing oxygen-rich gas into oxygen-rich region 220, the deposition of non-diamond carbon on microwave window 210 can be effectively suppressed. Furthermore, compared to the reference example, because the total oxygen content of the oxygen-rich gas and the reaction gas is sufficient for diamond growth, the overall feed gas concentration in the plasma reaction chamber remains unchanged. The feed gas composition of CH4 / H2 / CO2 in the plasma reaction chamber remains unchanged, preventing normal diamond growth and thus preventing a reduction in the diamond growth rate.

[0056] Furthermore, since a small amount of non-diamond carbon is still deposited on the surface of the microwave window 210 in the above embodiment, 90% to 100% of oxygen with a flow rate of 3.0 sccm can be sprayed as oxygen-rich gas into the oxygen-rich region 220 to remove the non-diamond carbon deposited on the surface of the microwave window 210 to achieve different etching effects.

[0057] Please refer to FIG3 , which shows a schematic diagram of a first current balancing ring provided according to some embodiments of the present invention.

[0058] As shown in Figure 3, the first flow balancing ring 310 can be disposed on the lower surface of the microwave window 320 via a vacuum sealing ring 330 to surround the microwave window 320. In the embodiment shown in Figure 3, the first flow balancing ring 310 can also be provided with a second air flow channel isolated from the first air flow channel. The first air flow channel is fed with oxygen-rich gas via an air inlet pipe 341 of the gas supply system, and the oxygen-rich gas is ejected through a first air outlet connected to the first air flow channel. The first air outlet can be disposed on the inner side of the first flow balancing ring to eject the oxygen-rich gas toward A, toward the center of the microwave window 320. The second air flow channel can be fed with reactant gas via an air inlet pipe 342 of the gas supply system, and the reactant gas is ejected through a second air outlet connected to the second air flow channel. The second air outlet can be disposed on the underside of the first flow balancing ring to eject the reactant gas toward B, toward the reaction area below. Optionally, the orientation and arrangement of the first and second air outlets can be adaptively adjusted as needed.

[0059] In another optional embodiment, a second flow balancing ring can be provided in the vacuum chamber, and a plurality of third gas outlet holes are provided on the second flow balancing ring. The gas supply system passes the reaction gas into the second flow balancing ring, and the reaction gas is ejected into the reaction area in the vacuum chamber through the third gas outlet holes.

[0060] Optionally, the first and second current balancing rings can be positioned at the same height, or the second current balancing ring can be positioned parallel to or slightly above the reaction zone. The first air outlet can be positioned on the inner side of the first current balancing ring, oriented toward the center of the microwave window. The third air outlet can be positioned on the underside of the second current balancing ring, oriented toward the reaction zone within the vacuum chamber.

[0061] In summary, the plasma reaction chamber provided by the present invention can etch solid deposits deposited on the surface of the microwave window during the plasma reaction process, inhibit the formation of solid deposits in the surface area of ​​the microwave window, and thus reduce the contamination of the microwave window surface by solid deposits during the plasma reaction.

[0062] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A plasma reaction chamber, comprising: A vacuum chamber, wherein the vacuum chamber includes a base structure extending from the outside into the cavity, and a microwave window is provided on the top of the vacuum chamber above the base structure for allowing microwaves to enter the vacuum chamber to excite the reaction gas in the reaction area; The vacuum chamber comprises a first flow balancing ring, which is arranged at the top of the vacuum chamber and surrounds the microwave window. A first airflow channel is arranged inside the first flow balancing ring. The first flow balancing ring is provided with a plurality of first gas outlet holes connected with the first gas flow channel, and the first gas flow channel supplies oxygen-rich gas into the vacuum chamber through the first gas outlet holes. The orientations of the plurality of first gas outlet holes are arranged so that the oxygen-rich gas ejected from the first gas outlet holes forms an oxygen-rich area on the surface of the microwave window, and the oxygen content in the oxygen-rich area is higher than that in the reaction area.

2. The plasma reaction chamber according to claim 1, wherein: A second airflow channel isolated from the first airflow channel is arranged inside the first flow equalizing ring, and a plurality of second gas outlets connected to the second airflow channel are provided for supplying reaction gas to the reaction area in the vacuum chamber.

3. The plasma reaction chamber according to claim 1, wherein: The vacuum chamber further includes a second flow balancing ring, on which a plurality of third gas outlet holes are provided for supplying reaction gas to the reaction area in the vacuum chamber.

4. The plasma reaction chamber according to claim 1, wherein: The plurality of first air outlet holes are oriented toward a center of the microwave window.

5. The plasma reaction chamber according to claim 1, wherein: The first current equalizing ring is arranged along the lower edge of the microwave window and closely attached to the lower surface of the microwave window.

6. The plasma reaction chamber according to claim 1, wherein: The plurality of first air outlet holes are distributed in a centrally symmetrical manner.

7. The plasma reaction chamber according to claim 1, wherein: The oxygen-rich gas is a gas containing oxygen and / or carbon monoxide.

8. The plasma reaction chamber according to claim 1, wherein: The oxygen-rich gas is pure oxygen and is used to remove the deposited carbon on the surface of the microwave window.

9. The plasma reaction chamber according to claim 1, wherein: The sum of the oxygen content of the oxygen-rich region and the oxygen content of the reaction region constitutes the oxygen content required for growing diamond.

10. A microwave plasma chemical vapor deposition device, characterized in that: The invention comprises a microwave system, a vacuum system, a gas supply system, and a plasma reaction chamber as claimed in any one of claims 1 to 9.

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