A molybdenum ring for diamond growth

Abstract

The present invention relates to the field of chemical vapor deposition, and discloses a molybdenum ring for diamond growth. The key technical points of the technical solution are as follows: it includes a molybdenum ring body, and through holes are formed on the molybdenum ring body. The through holes are used to externally connect diamond substrates of different sizes so that the four side edges of the diamond substrates can be in contact with the inner walls of the through holes. The through holes are in a centrosymmetric shape formed by the orthogonality of two identical ellipses. Through the setting of the through holes, the present invention enables the side edges of the diamond substrates to be in contact with the molybdenum ring body through the through holes, and specifically shows line contact, so that the heat dissipation conditions of the side edges of the diamond substrates are similar, thereby improving the uniformity of heat dissipation in the side direction of the diamond substrates, and diamond substrates of continuously variable different sizes can be placed. During the diamond growth process, the overall temperature distribution of the substrate is made uniform, and other problems in the diamond growth process are solved, which is of great significance for the research on the growth of high-quality diamonds.

Description

Technical Field

[0001] The present invention relates to the field of chemical vapor deposition, and more particularly to a molybdenum ring for diamond growth. Background Art

[0002] Diamond has outstanding physical and chemical properties, such as high hardness, high thermal conductivity (2000 W·m-1·K-1 at room temperature), wide bandgap width (5.47 eV), high mobility, high light transmittance and wide light transmission range. It is not only widely used in traditional industrial applications such as machining, heat sinks, vacuum / optical windows, etc., but also has potential application value in frontier technology fields such as quantum computing, radiation / ultraviolet detection, and integrated circuit power devices.

[0003] Microwave plasma chemical vapor deposition (MPCVD) is an ideal method for preparing artificial diamonds. Compared with the high temperature and high pressure method, the CVD diamonds grown have better purity and larger size, which is conducive to the development of applications of large-size high-quality diamonds. In the microwave method, microwaves are usually used as an energy source to excite gases such as CH4 and H2 into a plasma state to form a stable plasma sphere, and then diamonds are deposited and grown on the substrate. The MPCVD method has the advantages of non-polar discharge, less pollution, and can prepare diamonds on a large area, and its products are widely used in the jewelry industry and high-tech fields such as semiconductors.

[0004] After the plasma stabilizes in the deposition chamber, the heat distribution is very uneven. The temperature is roughly the highest at the center of the plasma and decreases in a gradient towards the surroundings. Temperature is an important factor affecting the deposition of diamond grains because it affects the impurity absorption rate, which in turn affects the uniformity of the growth layer. The uneven temperature also causes problems such as crystal morphology, growth rate, and cracking. Therefore, before growth, a substrate with a flat surface needs to be selected to obtain a good contact area with the substrate holder to ensure heat dissipation. However, the actual surface of the substrate is not a completely flat plane, and the fit between the surfaces directly in contact with the substrate holder is still not tight enough. The areas with poor contact will have a greater impact on heat dissipation, resulting in uneven temperature distribution across the substrate. At the same time, due to the strong fluidity of the gas entering the chamber during the production process, when the gas flow enters the voids at the bottom of the substrate, the problem of substrate drift on the horizontal plane is likely to occur, which should be avoided during the growth of high-quality diamonds. To solve the problems of uneven heat conduction and substrate drift, CN104185697B discusses a method of brazing a single-crystal diamond substrate to the substrate holder and some suitable brazing alloys to obtain good adhesion and thermal contact between the substrate and the substrate holder, so as to improve the uniformity and yield of single-crystal CVD synthetic diamond products. CN104972189B uses a vacuum brazing method to firmly bond the diamond sample to the molybdenum substrate, preventing the problem that the seed crystal is blown off from the optimal position due to excessive gas flow during vacuum pumping and gas introduction, and ensuring the stability of the growth process to a certain extent. However, in the vacuum brazing method, a suitable welding medium needs to be used, usually a specially formulated alloy, which requires both improving the compatibility with the diamond seed crystal and not forming a severe reaction interface layer, thus bringing difficulties to the implementation of this method. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a molybdenum ring for diamond growth to solve the problem of uneven heat dissipation caused by non-tight contact between the diamond substrate surface in the prior art, and to deal with the problems that it is not easy to select a molybdenum ring of appropriate size due to the different sizes of diamond substrates and the problem of diamond substrate drift.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A molybdenum ring for diamond growth, including a molybdenum ring body, through holes are formed on the molybdenum ring body, and the through holes are used to externally connect diamond substrates of different sizes so that the four side edges of the diamond substrate can be in contact with the inner walls of the through holes. A supporting portion is formed on the molybdenum ring body, and the supporting portion protrudes from the molybdenum ring body into the through hole, and the supporting portion is used to support the diamond substrate.

[0008] The through holes are in a centrosymmetric shape formed by the orthogonality of two identical ellipses.

[0009] In the present invention, preferably, the ratio of the major axis length to the minor axis length of the through hole conforms to the following formula:

[0010]

[0011] where a represents the major axis length of the ellipse, and b represents the minor axis length of the ellipse.

[0012] In the present invention, preferably, the size of the molybdenum ring body and the size of the through hole conform to the following formula:

[0013] a + 10 mm ≤ Φ ≤ a + 20 mm,

[0014] where Φ represents the diameter of the molybdenum ring body.

[0015] In the present invention, preferably, the supporting portion is specifically annular, and the shape of the supporting portion is adapted to the shape of the through hole.

[0016] In the present invention, preferably, the width of the protrusion of the supporting portion is set to 0.1 to 0.5 mm, and the height of the supporting portion is set to 0.5 to 1 mm.

[0017] Advantages of the present invention:

[0018] 1. Through the setting of the through hole in the present invention, the side edges of the diamond substrate are brought into contact with the molybdenum ring body by means of the through hole, and specifically, it is a line contact, so that the heat dissipation conditions of the sides of the diamond substrate are similar, thereby improving the uniformity of heat dissipation in the side direction of the diamond substrate. Through the setting of the supporting portion, the diamond substrate can be separated from the contact with the water-cooled table, which maximally avoids the problem of uneven heat dissipation caused by uneven contact area, improves the uniformity of temperature distribution during diamond growth, and thus improves the uniformity of diamond growth. Moreover, the setting of the supporting portion makes the bottom of the diamond substrate have an open gap, so when the air flow enters the bottom of the diamond substrate, it is not easy to generate disturbance, alleviating the problem of substrate drift on the horizontal plane;

[0019] 2. Setting the shape of the through hole to be elliptical enables the variable size of the diamond substrate that can be placed to be a continuous rather than a discrete quantity, which can accommodate diamond substrates of different sizes, has strong versatility, and makes it easier for the substrate to fit a molybdenum ring of a suitable size. Place the diamond substrate into the through hole and rotate it clockwise or counterclockwise until the four side edges of the diamond substrate are in contact with the inner wall of the through hole. After placement, the through hole restricts the drift of the diamond substrate in the horizontal plane direction and restricts the direction of rotational drift of the diamond substrate, further reducing the possibility of the diamond substrate drifting. Description of the Drawings

[0020] Figure 1It is a top view structural schematic diagram of the molybdenum ring body in this embodiment;

[0021] Figure 2 It is a schematic diagram of the placement methods of diamond substrates of different sizes in this embodiment;

[0022] Figure 3 is Figure 2 a schematic diagram of the actual perspective of the placement method of the second substrate 402 in

[0023] Reference numerals:

[0024] 10: Molybdenum ring body;

[0025] 20: Supporting part;

[0026] 30: Through hole;

[0027] 401: First substrate;

[0028] 402: Second substrate;

[0029] 403: Third substrate Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] It should be noted that when a component is referred to as "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component at the same time. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used herein in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] Please also refer to Figures 1 to 3, this embodiment provides a molybdenum ring for diamond growth, including a molybdenum ring body 10, and a through hole 30 is formed on the molybdenum ring body 10. The through hole 30 is used to externally connect diamond substrates of different sizes so that the four side edges of the diamond substrate can be in contact with the inner wall of the through hole 30. Through the setting of the through hole 30 in the present invention, the side edges of the diamond substrate are made to contact the molybdenum ring body 10 by means of the through hole 30, and specifically, it is a line contact, so that the heat dissipation conditions of the sides of the diamond substrate are similar, thereby improving the uniformity of heat dissipation of the diamond substrate in the side direction.

[0034] In this implementation scheme, as shown in reference to Figure 1 and Figure 2 , the through hole 30 is a centrosymmetric shape formed by the orthogonality of two identical ellipses. Setting the shape of the through hole 30 to an ellipse enables the variable size of the diamond substrate that can be placed to be a continuous rather than a discrete quantity, and diamond substrates of different sizes can be accommodated. And by rotating the diamond substrate clockwise or counterclockwise, the four vertical edges of diamond substrates of different sizes can ultimately maintain good contact with the inner edge of the through hole 30, thereby improving the uniformity of heat dissipation of the diamond substrate. Place the diamond substrate into the through hole 30 and rotate it clockwise or counterclockwise until the four side edges of the diamond substrate are all in contact with the inner wall of the through hole 30. After placement, the through hole 30 restricts the drift of the diamond substrate in the horizontal plane direction and restricts the direction of rotation and drift of the diamond substrate, further reducing the possibility of the diamond substrate drifting.

[0035] In this implementation scheme, as shown in reference to Figure 1 and Figure 2 , the ratio of the length of the major axis to the length of the minor axis of the through hole 30 conforms to the following formula:

[0036]

[0037] where a represents the length of the major axis of the ellipse and b represents the length of the minor axis of the ellipse.

[0038] The size of the molybdenum ring body 10 and the size of the through hole 30 conform to the following formula:

[0039] a + 10mm ≤ Φ ≤ a + 20mm,

[0040] where Φ represents the diameter of the molybdenum ring body 10. The size of the molybdenum ring body 10 is set to Φ multiplied by 1.5mm.

[0041] And under the above constraints, the side length of the actually placeable diamond substrate conforms to the following formula:

[0042]

[0043] where c represents the side length of the diamond substrate.

[0044] In this embodiment, specifically refer to Figure 2 as shown, where the first substrate 401 is the smallest-sized substrate on which the molybdenum ring body 10 can be placed, the third substrate 403 is the largest-sized substrate on which the molybdenum ring body 10 can be placed, and the size of the second substrate 402 is between the first substrate 401 and the third substrate 403. The elliptical shape setting enables the variable size of the diamond substrate that can be placed to be a continuous rather than a discrete quantity, such that any value of the side length of the diamond substrate between 0.5a and √2 / 2 a can be used as the side length of the diamond substrate.

[0045] In this embodiment, specifically refer to Figure 3 as shown, a supporting portion 20 is formed on the molybdenum ring body 10. The supporting portion 20 protrudes from the molybdenum ring body 10 into the through hole 30. The supporting portion 20 is used to support the diamond substrate, which can keep a certain distance between the substrate and the water-cooling table. The supporting portion 20 is specifically annular, and the shape of the supporting portion 20 is adapted to the shape of the through hole 30, thereby facilitating the support of diamond substrates of different sizes. The four corners of the diamond substrate are kept in contact with the supporting portion 20. The width of the protrusion of the supporting portion 20 is set to be 0.1 to 0.5 mm, and the height of the supporting portion 20 is set to be 0.5 to 1 mm. To reduce the contact area with the bottom of the diamond substrate, the protruding width of the supporting portion 20 is as small as possible, being 0.1 - 0.5 mm. To avoid the influence of the water-cooling table on the excessive local heat dissipation of the bottom surface of the substrate, the height of the supporting portion 20 is 0.5 - 1 mm.

[0046] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. Any technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A molybdenum ring for diamond growth, characterized in that: It includes a molybdenum ring body, and a through hole is formed on the molybdenum ring body. The through hole is used to externally connect diamond substrates of different sizes so that the four side edges of the diamond substrate can be in contact with the inner wall of the through hole, specifically in line contact. A supporting portion is formed on the molybdenum ring body. The supporting portion protrudes from the molybdenum ring body into the through hole, and the supporting portion is used to support the diamond substrate. The through hole has a centrosymmetric shape formed by the orthogonality of two identical ellipses, so that the variable size of the diamond substrate that can be placed is a continuous rather than a discrete quantity, and diamond substrates of different sizes can be accommodated.

2. The molybdenum ring for diamond growth according to claim 1, wherein: The ratio of the length of the major axis to the length of the minor axis of the through hole conforms to the following formula: , where a represents the length of the major axis of the ellipse and b represents the length of the minor axis of the ellipse.

3. The molybdenum ring for diamond growth according to claim 2, characterized in that: The size of the molybdenum ring body and the size of the through hole conform to the following formula: ， where Φ represents the diameter of the molybdenum ring body.

4. The molybdenum ring for diamond growth according to claim 1, wherein: The supporting portion is specifically annular, and the shape of the supporting portion is adapted to the shape of the through hole.

5. The molybdenum ring for diamond growth according to claim 4, characterized in that: The width of the protruding supporting portion is set to 0.1 to 0.5 mm, and the height of the supporting portion is set to 0.5 to 1 mm.

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