Cavity structure for microwave plasma chemical vapor deposition equipment

Abstract

The utility model provides a cavity structure for microwave plasma chemical vapor deposition equipment, which is used for enabling a microwave to form a microwave field and comprises a shell and an objective table. The shell comprises an inner bottom face, an inner top face and an inner ring wall face. The inner top face and the inner bottom face are spaced and face each other, the diameter of the inner bottom face is larger than that of the inner top face, and the inner top face protrudes towards the inner bottom face. The two ends of the inner ring wall face are connected with the inner top face and the inner bottom face respectively, so that a cavity is formed among the inner bottom face, the inner top face and the inner ring wall face. The microwave field is located in the chamber. The objective table is arranged in the cavity and provided with an objective surface, and the objective surface faces the inner top surface. According to the cavity structure disclosed by the utility model, the phenomenon of double fireballs can be avoided, and the influence on a microwave plasma chemical vapor deposition reaction is reduced.

Description

Technical Field

[0001] This utility model relates to a component of a microwave plasma chemical vapor deposition (CVD) apparatus, and more particularly to a cavity structure for a microwave plasma chemical vapor deposition (CVD) apparatus. Background Technology

[0002] Microwave plasma-assisted chemical vapor deposition (MPCVD) is a chemical vapor deposition method that uses a microwave field to create a strong field region that excites reactive gases, causing them to dissociate and produce a high-temperature fireball in a plasma state. The free atoms are guided to attach to a specific object and stack according to a specific atomic arrangement to form a specific structure. A common application of MPCVD is the manufacture of synthetic diamonds. It uses hydrogen to generate a high-temperature plasma, which guides the ionization of carbon atoms in methane, allowing the carbon atoms to deposit onto a seed crystal, forming a diamond crystal according to a specific atomic arrangement. Currently, MPCVD equipment on the market mainly uses three types of cavity structures: cylindrical cavity, French cavity, and dish cavity, with the dish cavity structure having several different designs.

[0003] Please refer to Figure 5 This design, 90, is a traditional dish-shaped cavity structure in MPCVD equipment. Due to its superior microwave field uniformity, it is widely favored and adopted. However, during MPCVD operation, within the cavity structure 90, in addition to the growth zone 92 above the growth stage 91, another primary strong field zone 93 is formed near the top of the cavity. This often leads to a double fireball phenomenon, with fireballs appearing simultaneously from both above and below, interfering with the deposition process. Furthermore, it can be observed that in the traditional dish-shaped cavity structure 90, the growth zone 92 formed above the growth stage 91 is relatively high, and the contact area between the bottom of the growth zone 92 and the growth stage 91 is relatively small. This results in inconsistent growth rates between the outer and central portions of the semi-finished product during deposition, leading to internal stress and increased susceptibility to cracking.

[0004] In view of this, the traditional disc cavity structure in MPCVD equipment, as described above, clearly needs to be improved. Utility Model Content

[0005] The main objective of this invention is to propose a cavity structure for a microwave plasma chemical vapor deposition (CVD) device that can prevent the formation of two strong field regions during use and thus prevent the generation of a double fireball phenomenon.

[0006] To achieve the aforementioned objectives, the present invention proposes a cavity structure for a microwave plasma chemical vapor deposition (CCVD) apparatus, which allows a microwave to form a microwave field. This cavity structure for the microwave plasma chemical vapor deposition apparatus includes:

[0007] An outer casing comprising:

[0008] An inner bottom surface and an inner top surface, spaced apart from each other and facing each other, the diameter of the inner bottom surface is larger than the diameter of the inner top surface, and the inner top surface protrudes towards the inner bottom surface; and

[0009] An inner ring wall, with its two ends connected to the inner top surface and the inner bottom surface respectively, thereby forming a cavity between the inner bottom surface, the inner top surface, and the inner ring wall, and the microwave field is located in the cavity; and

[0010] A stage is disposed in the chamber, the stage having a loading surface facing the inner top surface.

[0011] Therefore, the advantage of this invention is that the microwave field forms a strong field growth region on the stage, and due to the shape of the cavity of this invention, since the growth region is located below the inner top surface, the protruding inner top surface prevents the microwave field from forming another strong field region above the growth region. Thus, the cavity structure of this invention can avoid the occurrence of the double fireball phenomenon.

[0012] The cavity structure for a microwave plasma chemical vapor deposition apparatus as described above, wherein the inner top surface is an arc surface.

[0013] As described above for the cavity structure of a microwave plasma chemical vapor deposition apparatus, the inner diameter of the portion of the cavity surrounded by the inner ring wall gradually decreases from the inner bottom surface to the inner top surface.

[0014] As previously described, the cavity structure for a microwave plasma chemical vapor deposition apparatus has an inner bottom surface recessed away from the inner top surface.

[0015] As described above, the cavity structure for a microwave plasma chemical vapor deposition apparatus includes a housing having a chassis component with an inner bottom surface located on the chassis component; a peripheral wall component that is sealed to the periphery of the chassis component and extends away from the chassis component, with an inner circumferential wall surface located on the peripheral wall component; and a top cover component that is sealed at one end of the peripheral wall component relative to the chassis component.

[0016] The cavity structure for a microwave plasma chemical vapor deposition apparatus as described above, wherein the housing further has at least one air inlet formed through the peripheral wall member, and the at least one air inlet is located close to the top cover member.

[0017] The cavity structure for the microwave plasma chemical vapor deposition apparatus described above further includes a microwave tube connected to the chassis and communicating with the cavity.

[0018] As described above for the cavity structure of a microwave plasma chemical vapor deposition apparatus, the top cover is detachably connected to the peripheral wall.

[0019] The cavity structure for the microwave plasma chemical vapor deposition apparatus described above further includes a cooler that passes through the housing and is connected to the stage.

[0020] The cavity structure for a microwave plasma chemical vapor deposition apparatus as described above, wherein the microwave frequency band is between 900 and 930 MHz or between 2400 and 2500 MHz. Attached Figure Description

[0021] Figure 1 This is a three-dimensional appearance diagram of the present utility model.

[0022] Figure 2 This is a side sectional view of the present invention.

[0023] Figure 3 for Figure 2 A partially enlarged schematic diagram.

[0024] Figure 4 This is a schematic diagram of the microwave field formed within the cavity structure of this utility model.

[0025] Figure 5 This is a schematic diagram of the microwave field formed by microwaves within a traditional dish cavity structure. Detailed Implementation

[0026] Please refer to Figures 1 to 4 This invention proposes a cavity structure for a microwave plasma chemical vapor deposition apparatus, which allows a microwave to form a microwave field within it. This invention is preferably used to form a microwave field using microwaves with frequencies between 900 MHz and 930 MHz or between 2400 MHz and 2500 MHz, but is not limited thereto.

[0027] The cavity structure of this utility model for a microwave plasma chemical vapor deposition apparatus includes a shell 10, a stage 30, a microwave tube 40, and a cooler 50.

[0028] The outer shell 10 includes an inner bottom surface 21, an inner top surface 22, and an inner ring wall surface 23. The two ends of the inner ring wall surface 23 are connected to the inner bottom surface 21 and the inner top surface 22, respectively. The inner bottom surface 21, the inner top surface 22, and the inner ring wall surface 23 together surround and form a cavity 20, and the microwave field generated by the microwave is located inside the cavity 20.

[0029] The inner bottom surface 21 and the inner top surface 22 are spaced apart from each other and face each other. In this embodiment, the inner bottom surface 21 and the inner top surface 22 are circular surfaces, and the diameter of the inner bottom surface 21 is larger than the diameter of the inner top surface 22, thereby forming a dish shape in the cavity 20 with a narrower upper bottom surface and a wider lower bottom surface. The inner top surface 22 is a reflective surface used to reflect microwaves. The inner top surface 22 protrudes towards the inner bottom surface 21 to form an arc-shaped structure, but it is not limited to this. The inner top surface 22 can also be other shapes, as long as it protrudes towards the inner bottom surface 21 and occupies a part of the space at the top of the cavity 20.

[0030] In this embodiment, the inner bottom surface 21 is further recessed away from the inner top surface 22. Specifically, the inner bottom surface 21 includes a peripheral portion 211 and a central portion 212. The peripheral portion 211 surrounds and connects to the central portion 212. The central portion 212 is a plane and the peripheral portion 211 is an inclined surface. In the radial direction of the inner bottom surface 21, the peripheral portion 211 gradually slopes from the inside to the outside towards the inner top surface 22, but this is not a limitation. The form of the inner bottom surface 21 can be adjusted according to requirements.

[0031] Furthermore, in this embodiment, the inner diameter of the portion of the chamber 20 surrounded by the inner ring wall 23 gradually decreases from the inner bottom surface 21 to the inner top surface 22. Specifically, as... Figure 3 As shown, the inner ring wall 23 gradually slopes inward from the inner bottom surface 21 to the inner top surface 22, forming a shape similar to an inverted funnel. This forms the cavity 20 in a shape similar to a truncated cone, but it is not limited to this. The shape of the cavity 20 and the form of the inner ring wall 23 can be adjusted as needed. For example, the inner ring wall 23 can also be a curved surface with an arc edge in the height direction of the cavity 20, or it can be a stepped surface.

[0032] In this embodiment, the outer shell 10 is composed of a chassis component 11, a peripheral wall component 12, and a top cover component 13, but this is not a limitation. The inner bottom surface 21 is located on the chassis component 11, the inner ring wall surface 23 is located on the peripheral wall component 12, and the inner top surface 22 is located on the top cover component 13. The peripheral wall component 12 is sealed to the periphery of the chassis component 11 and extends away from the chassis component 11, while the top cover component 13 is sealed at one end of the peripheral wall component 12 relative to the chassis component 11.

[0033] The top cover 13 is preferably detachably disposed on the peripheral wall 12, and the top cover 13 may have different forms of inner top surface 22, thereby facilitating the user to replace the top cover 13 as needed, but is not limited thereto.

[0034] The outer casing 10 has at least one air inlet 121 through it. In this embodiment, the air inlet 121 is formed on the peripheral wall member 12 and the position of the air inlet 121 is close to the top cover member 13, but it is not limited thereto; for example, in other embodiments, the air inlet 121 may also be located on the top cover member 13.

[0035] Please refer to Figures 2 to 4 A stage 30 is disposed in the chamber 20. The stage 30 has a loading surface 31 facing the inner top surface 22. The stage 30 is used to hold a substrate (not shown in the figure), such as a diamond seed crystal. The substrate can be placed on the loading surface 31 and below the inner top surface 22. In this embodiment, the stage 30 and the inner bottom surface 21 are spaced apart, and the periphery of the loading surface 31 has a chamfered structure to facilitate the flow of working gas (not shown in the figure) and the propagation of microwaves to form a microwave field and a plasma fireball, but this is not a limitation. A microwave tube 40 is connected to the chassis 11 and communicates with the chamber 20. Microwaves enter and exit the chamber 20 through the microwave tube 40. A cooler 50 passes through the outer shell 10 and is connected to the stage 30. Specifically, the cooler 50 is a closed flow channel that allows cooling fluid to flow inside to remove heat, thereby controlling the high-temperature plasma fireball, but this is not a limitation.

[0036] Please refer to Figure 3 and Figure 4 When in use, the cavity structure of this invention, through the shape of the cavity 20, allows the microwave field to form a strong field growth region 60 on the stage 30. Since the growth region 60 is located below the inner top surface 22, the protruding inner top surface 22 prevents the microwave field from forming another strong field region above the growth region 60. Therefore, the cavity structure of this invention can avoid the occurrence of the double fireball phenomenon and reduce the impact on the microwave plasma chemical vapor deposition reaction.

[0037] Furthermore, please refer to Figure 4 and Figure 5Compared to existing technologies, the cavity structure of this invention allows for a flatter and wider growth region 60 formed by the microwave field. If this invention and existing technologies are used to manufacture synthetic diamonds, the wider growth region 60 of this invention ensures that, for the same growth area, the growth rate at the outer edge of the synthetic diamond is highly consistent with the central strong field region. This means that the overall growth rate is highly consistent during the growth process, preventing uneven growth thickness in the final product due to inconsistent growth rates, which could lead to stress-induced cracking and improve product yield. This also means that this invention can be used to grow products with larger areas to meet more diverse market demands.

[0038] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to preferred embodiments, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model's technical solution. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the content of the present utility model's technical solution shall still fall within the scope of the present utility model's technical solution.

Claims

1. A cavity structure for a microwave plasma chemical vapor deposition apparatus, characterized in that, The cavity structure of the microwave plasma chemical vapor deposition apparatus, used to generate a microwave field, includes: An outer casing comprising: An inner bottom surface and an inner top surface, spaced apart from each other and facing each other, the diameter of the inner bottom surface is larger than the diameter of the inner top surface, and the inner top surface protrudes towards the inner bottom surface; and An inner ring wall, with its two ends connected to the inner top surface and the inner bottom surface respectively, thereby forming a cavity between the inner bottom surface, the inner top surface, and the inner ring wall, and the microwave field is located in the cavity; and A stage is disposed in the chamber, the stage having a loading surface facing the inner top surface.

2. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in claim 1, characterized in that, The inner top surface is an arc surface.

3. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in claim 1, characterized in that, The inner diameter of the chamber, which is surrounded by the inner ring wall, gradually narrows from the inner bottom surface to the inner top surface.

4. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in claim 1, characterized in that, The inner bottom surface is recessed in a direction away from the inner top surface.

5. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in any one of claims 1 to 4, characterized in that, The housing has: A chassis component, wherein the inner bottom surface is located on the chassis component; A peripheral wall component, which is sealingly connected to the periphery of the chassis component and extends away from the chassis component, wherein the inner annular wall surface is located within the peripheral wall component; and A top cover, the sealing of which is located at one end of the peripheral wall relative to the chassis.

6. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in claim 5, characterized in that, The housing further has: At least one air inlet is formed through the peripheral wall member, and the position of the at least one air inlet is close to the top cover member.

7. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in claim 5, characterized in that, Further features: A microwave tube is connected to the chassis component and communicates with the cavity.

8. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in claim 5, characterized in that, The top cover is detachably connected to the peripheral wall.

9. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in any one of claims 1 to 4, characterized in that, It further has the following characteristics: A cooler is installed through the housing and connected to the platform.

10. The cavity structure for a microwave plasma chemical vapor deposition apparatus as described in any one of claims 1 to 4, characterized in that, The microwave operates in a frequency band between 900 and 930 MHz or between 2400 and 2500 MHz.

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