CN114231943A

CN114231943A - Two-stage lifting system and equipment for chemical vapor deposition

Info

Publication number: CN114231943A
Application number: CN202111517191.5A
Authority: CN
Inventors: 全峰; 顾亚骏; 蒋礼
Original assignee: Shenzhen Upl Plasma Technology Co ltd
Current assignee: Shenzhen Upl Plasma Technology Co ltd
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2022-03-25

Abstract

The invention provides a secondary lifting system and equipment for chemical vapor deposition, which comprise a first lifting system and a second lifting system, wherein the first lifting system adopts the technical scheme of a vacuum corrugated pipe, and the second lifting system is fixedly arranged in a first support and can move up and down along with the first lifting system. The second lifting system comprises a second reaction platform, a transmission module, a magnetic fluid sealing module and a driving piece which are sequentially arranged, the transmission module is used for converting the rotation of the driving piece into up-down movement, and the magnetic fluid sealing module realizes the sealing environment of the second lifting system and the reaction cavity in the movement. According to the invention, the second lifting system is arranged, and the heights of the first lifting system and the second lifting system are adjusted, so that the technical problem that after the diamond grows for a period of time, the surface of the seed crystal and the surface of a polycrystalline deposition layer can form an obvious height difference, and further the temperature fluctuates in the growth process of the seed crystal is solved.

Description

Two-stage lifting system and equipment for chemical vapor deposition

Technical Field

The invention belongs to the technical field of diamond growth, and particularly relates to a secondary lifting system for chemical vapor deposition and equipment comprising the secondary lifting system for chemical vapor deposition.

Background

This section provides background information related to the present application and is not necessarily prior art.

The diamond has the characteristics of high hardness, high elastic modulus, high thermal conductivity, high wear resistance, high thermal conductivity, high chemical stability, high optical transparency, low thermal expansion coefficient and the like, and the unique physical and chemical properties are combined together to enable the diamond to be applied to a plurality of fields, so that the diamond becomes one of the most potential novel functional materials in recent decades, the diamond not only has wide application in the well-known ultra-precision machining field, but also has infinite potential in the high-end technical fields of optics, particle detectors, semiconductor components and the like.

The Microwave Plasma Chemical Vapor Deposition (MPCVD) has the working principle that a reaction cavity is vacuumized, the tightness of the reaction cavity is kept all the time, microwaves generated by a microwave generator enter the resonant reaction cavity through a waveguide tube, mixed reaction gas of carbon source gas and hydrogen is introduced, glow discharge is generated in the resonant reaction cavity under the excitation of the microwaves, the reaction gas is ionized to form various active groups, then the various active groups perform a series of chemical reactions on seed crystals and gradually perform adsorption, desorption, migration, diffusion and deposition on the surfaces of the seed crystals, and finally the diamond is obtained. Because the reaction gas is excited by the energy of electromagnetic waves, the plasma is pure, the discharge area of the microwave is concentrated and does not expand, various atomic groups such as atomic hydrogen and the like can be activated and generated, the maximum kinetic energy of generated ions is low, and the generated diamond cannot be corroded. Therefore, MPCVD has become one of the best methods for growing diamond.

In diamond growth, a seed is typically placed in the middle region of the reaction table (seed region) for growing diamond. At the same time, polycrystalline deposits are also formed in the edge regions of the reaction chamber (seed-free regions). The great practice shows that the growth speed of the diamond and the growth speed of the polycrystalline deposition layer have difference, and the obvious height difference is formed on the surface of the seed crystal and the surface of the polycrystalline deposition layer along with the continuous increase of the growth time of the diamond, and the height difference influences the change of the growth environment of the diamond, and the most obvious change is the change of the growth temperature of the seed crystal, because the plasma temperature is gradually reduced from the center to the edge. The height difference formed between the surface of the seed crystal and the surface of the polycrystalline deposition layer can cause excessive or too little energy absorption of a seed crystal area, so that the temperature fluctuation in the growth process of the seed crystal is caused, and the growth of high-quality diamond is not facilitated. At the same time, some of the microwave energy is not efficiently utilized, resulting in waste.

Disclosure of Invention

The invention mainly has two purposes, the first purpose is to provide a two-stage lifting system for chemical vapor deposition, so as to solve the technical problem that in the prior art, a seed crystal area and a seedless area can form obvious height difference in the diamond growth process to cause diamond growth temperature fluctuation, and simultaneously, more microwave energy can be effectively utilized. A second object is to provide an apparatus comprising the above-described secondary lifting system for chemical vapor deposition.

To achieve the first object, the present invention provides a two-stage lift system for chemical vapor deposition. The method comprises the following steps: a first lifting system and a second lifting system. The first lifting system comprises a first reaction platform, a first support, a reaction cavity base plate, a screw rod, a vacuum corrugated pipe, a movable plate and a fixed plate, the first reaction platform is arranged on the first support, the first support penetrates through the reaction cavity base plate and is fixedly connected with the movable plate, two ends of the vacuum corrugated pipe are respectively and fixedly connected with the reaction cavity base plate and the movable plate, one end of the screw rod is movably connected with the reaction cavity base plate, the other end of the screw rod penetrates through the fixed plate, and the movable plate is sleeved on the screw rod; and the second lifting system is fixedly arranged on the first support and can move up and down along with the first support.

Further, the second lifting system comprises a second reaction platform, a transmission module, a magnetic fluid sealing module and a driving piece which are sequentially arranged; and a driving part fixing plate fixed with the driving part bolt is arranged on the driving part, and the driving part fixing plate is fixed with the magnetic fluid sealing module bolt.

Further, the magnetic fluid sealing module comprises a magnetic fluid, a magnetic fluid nut matched with the external thread of the magnetic fluid and a T-shaped magnetic fluid fixing flange, the T-shaped magnetic fluid fixing flange is arranged between the magnetic fluid and the second support in a penetrating mode, the magnetic fluid nut is used for sealing the magnetic fluid and the T-shaped magnetic fluid fixing flange, and the T-shaped magnetic fluid fixing flange is fastened with the second support through bolts.

Furthermore, the magnetic fluid sealing module also comprises metal gaskets arranged between the T-shaped magnetic fluid fixing flange and the magnetic fluid and between the T-shaped magnetic fluid fixing flange and the second support, and the sealing adopts a knife edge sealing mode.

Further, the transmission module comprises a second support and a rotating shaft, and one end, far away from the second reaction table, of the second support is in threaded fit with one end of the rotating shaft.

Furthermore, a through hole is formed in a screw hole gap formed by matching the second support and the rotating shaft through threads, so that gas residue is prevented when the reaction cavity is vacuumized.

Furthermore, a spring is arranged between the second bracket and the rotating shaft for connecting, and the spring is always kept in a tension state.

Furthermore, the transmission module further comprises a limiting device, the limiting device comprises a limiting ring fixed on the first lifting system by the connecting support, the limiting ring is provided with a limiting protrusion, and the limiting protrusion is matched with a limiting groove in the second support.

Further, the height moving range of the second lifting system is 0-20 mm.

To achieve the second object, the present invention also provides an apparatus comprising a secondary lift system as described above for chemical vapor deposition.

The technical scheme shows that the invention has the following beneficial effects:

1. the invention is provided with two-stage lifting systems, and the second lifting system is fixedly arranged on the first bracket and can move up and down along with the first lifting system. Therefore, the first lifting system and the second lifting system are positioned at the same height in the initial stage of diamond growth, and after the diamond grows for a period of time, the height of the first lifting system and the height of the second lifting system are adjusted to enable the surface of the seed crystal and the surface of the polycrystalline deposition layer to be at the preset reaction height, so that the temperature fluctuation in the growth process of the seed crystal is avoided;

2. the magnetic fluid sealing module arranged in the second lifting system ensures good sealing property between the second lifting system and the reaction cavity, and solves the contradiction between movement and sealing property;

3. the spring connection which is always kept in a tense state is arranged between the second bracket and the rotating shaft, so that unnecessary errors caused by gravity and thread space when the height of the second lifting system is changed are effectively avoided;

4. the screw hole gap that second support and rotating shaft screw-thread fit formed is provided with the through-hole, effectively prevents gaseous remaining when reaction chamber evacuation.

Drawings

FIG. 1 is a schematic cross-sectional view of a two-stage lift system according to the present invention;

FIG. 2 is a schematic cross-sectional view of a magnetic fluid seal module provided in accordance with the present invention;

FIG. 3 is a schematic cross-sectional view of a knife-edge seal arrangement provided in accordance with the present invention;

FIG. 4 is a schematic cross-sectional view of a transmission module according to the present invention;

FIG. 5 is a schematic cross-sectional view of a transmission module according to the present invention;

FIG. 6 is a schematic view of a transmission module provided with springs according to the present invention;

FIG. 7 is a schematic view of a transmission module according to the present invention with springs;

fig. 8 is a schematic structural view of the limiting device according to the present invention.

The reaction apparatus includes a first reaction table 11, a first support 12, a reaction chamber chassis 13, a lead screw 14, a fixed rod 15, a vacuum bellows 16, a movable plate 17, a fixed plate 18, a second reaction table 21, a transmission module 22, a rotating shaft 221, a second support 222, a screw hole gap 223, a through hole 224, a spring 225, a limit ring 226, a limit protrusion 227, a limit groove 228, a connecting support 229, a magnetic fluid sealing module 23, a magnetic fluid sealing module 231, a magnetic fluid nut 232, a T-shaped magnetic fluid fixing flange 233, a metal gasket 234, a coupler 24, a driving member 25, and a driving member fixing plate 26.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and the related technical features in the embodiments in the present application may be combined with each other. It should be noted that the following detailed description is intended to provide further explanation of the application, and unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The invention is described in detail below, with the same or similar reference numerals indicating the same or similar parts or having the same or similar functions throughout. In addition, if the description of the prior art documents or other prior art is not necessary for the technical solution provided by the present invention, it has been omitted in the present invention. The embodiments described in the present invention are for illustrative purposes only and are not intended to limit the technical solutions of the present invention.

In the prior art, the surface of a seed crystal and the surface of a polycrystalline deposition layer form obvious height difference, so that the technical problem of diamond growth temperature fluctuation is caused, and the aim of effectively utilizing more microwave energy is fulfilled. Wherein the equipment is used for growing diamond by the MPCVD method.

The technical solution of the present invention and how to solve the above technical problems are described in detail with specific embodiments below.

Referring to fig. 1, a two-stage lift system for chemical vapor deposition includes a first lift system and a second lift system. Wherein, first operating system includes first reaction platform 11, first support 12, reaction chamber chassis 13, the lead screw 14, vacuum bellows 16, activity dish 17 and fixed disk 18, first reaction platform 11 sets up on first support 12, first support 12 wear to locate reaction chamber chassis 13 and with activity dish 17 fixed connection, vacuum bellows 16 both ends respectively with reaction chamber chassis 13 and activity dish 17 fixed connection, 14 one end of lead screw and 13 swing joint in reaction chamber chassis, the fixed disk 18 is worn to locate by the other end, lead screw 14 is located to activity dish 17 cover. Thus, when the screw 14 is rotated by an external force, the screw 14 drives the movable disk 17 to move up and down, and then the movable disk 17 drives the vacuum bellows 16 and the first bracket 12 to move up and down, and finally the first bracket 12 drives the first reaction platform 11 to change the height. The action of the vacuum bellows 16 keeps the sealing performance of the reaction chamber under the condition that the first lifting system moves up and down, and prevents other impurity gases from flowing into the reaction chamber.

The reaction chamber chassis 13 is a part of the reaction chamber, and may be integrally formed with other reaction chamber parts, or may be a disk type, and is sealed with other reaction chamber parts to form the reaction chamber. The position of the screw rod 14 close to the fixed disc 18 is fixedly provided with a wheel groove, and the wheel groove is provided with a medium such as a belt or a chain connected with an external force device. The external force for driving the screw 14 to rotate can be provided by a motor or a rotary cylinder, and the like, specifically, the external force can provide a rotating force.

In addition, the fixed disk 18 can be fixed by other structures of the device, or can be fixed by a fixed rod 15, two ends of the fixed rod 15 are respectively fixedly connected with the reaction chamber chassis 13 and the fixed disk 18, the movable disk 17 is also sleeved on the fixed rod 15 like the screw rod 14, the movable disk 17 can rotate along with the screw rod 14, and the movable disk 17 further moves up and down on the fixed rod 15.

And the second lifting system is fixedly arranged on the first support 12 and can move up and down along with the first support 12. Thus, when the first lifting system ascends or descends, the second lifting system can ascend or descend along with the first lifting system. When the diamond grows, the first lifting system is controlled to reach the preset reaction height, the second lifting system also reaches the preset reaction height, and after the diamond grows for a period of time, the polycrystalline deposition layer of the first lifting system and the seed crystal layer of the second lifting system have obvious height difference. To eliminate this height difference and adjust the poly-deposition layer of the first lift system and the seed layer of the second lift system to a predetermined reaction height, the height of the second reaction system may be increased or decreased by decreasing the height of the first lift system.

The reaction height refers to the height at which reaction gas is ionized on the surface of the seed crystal and forms various active groups, and then the various active groups perform a series of chemical reactions on the surface of the seed crystal and gradually perform adsorption, desorption, migration, diffusion and deposition on the surface of the seed crystal.

In this embodiment, referring to fig. 1, the second lifting system includes a second reaction platform 21, a transmission module 22, a magnetic fluid sealing module 23 and a driving member 25, which are sequentially arranged; the driving member 25 is provided with a driving member fixing plate 26 bolted to the driving member 25, and the driving member fixing plate 26 is bolted to the magnetic fluid sealing module 23. The second reaction platform 21 is a seed crystal growth area, the transmission module 22 is used for transmitting power of the second lifting system to ensure that the second lifting system can move up and down, the magnetic fluid sealing module 23 is used for forming a sealing environment of the second lifting system and the reaction chamber, the driving part 25 is used for providing power for the second lifting system, and the driving part fixing plate 26 is used for fixing the driving part 25. The specific process is that the driving part 25 provides power for the magnetic fluid sealing module 23, the magnetic fluid sealing module 23 drives the transmission module 22, and the transmission module 22 realizes the up-and-down movement of the second reaction table 21.

Of course, in consideration of the fact that each part is a standard component, a coupler 24 may be sleeved between the magnetic fluid sealing module 23 and the driving member 25, and the coupler 24 is used to connect the driving member 25 and the magnetic fluid sealing module 23, so as to ensure that the magnetic fluid sealing module 23 rotates with the driving member 25.

The driving member 25 is a motor, a rotary cylinder, or the like, and is specifically limited to be capable of providing a rotational force.

In this embodiment, referring to fig. 2, the magnetic fluid sealing module 23 includes a magnetic fluid 231, a magnetic fluid nut 232 that is engaged with the external thread of the magnetic fluid 231, and a T-shaped magnetic fluid fixing flange 233, in order to ensure the sealing performance of the second lifting system, the T-shaped magnetic fluid fixing flange 233 is inserted between the magnetic fluid 231 and the second support 12, the magnetic fluid nut 232 is used for sealing the magnetic fluid 231 and the T-shaped magnetic fluid fixing flange 233, and the T-shaped magnetic fluid fixing flange 233 is fastened to the second support 12 by bolts. Thus, two sealing structures are formed, wherein one sealing structure consists of a T-shaped magnetic fluid fixing flange 233 and the second bracket 12 and is fastened by bolts; the other sealing structure is composed of a T-shaped magnetic fluid fixing flange 233 and a magnetic fluid 231, the sealing structure adopts a magnetic fluid nut 232 for fastening, and the two sealing structures form a sealing environment between the second lifting system and the reaction cavity.

The magnetic fluid is composed of a non-magnetic seat, a bearing, a magnetic pole, a permanent magnet, a magnetic shaft and a magnetic fluid, and under the action of a magnetic field, the magnetic fluid is filled in an annular space to establish a series of O-shaped sealing rings, so that the sealing effect is achieved.

In this embodiment, referring to fig. 3, the magnetic fluid sealing module 23 further includes a metal gasket 234 disposed between the T-shaped magnetic fluid fixing flange 233 and the magnetic fluid 231 and the second support 12, respectively, and the sealing is performed in a knife edge sealing manner. Due to the good metal sealing effect, the sealing performance of the second lifting system and the reaction chamber can be improved by the metal sealing mode of arranging the metal gasket 234 in the sealing structure. The knife edge sealing mode improves the sealing performance of the second lifting system and the reaction cavity. The knife edge sealing means that the sealing element is matched with a bulge and a groove with triangular sections, and the sealing element is deformed by extrusion to achieve the purpose of sealing.

In one embodiment, as shown in fig. 3, a T-shaped magnetic fluid fixing flange 233 with a triangular protrusion, a magnetic fluid 231, a second bracket 12 and a metal gasket 234 with a triangular groove can be used to cooperate to form a knife-edge sealing structure.

In another embodiment, not shown, a metal gasket 234 with a triangular protrusion, a T-shaped magnetic fluid fixing flange 233 with a triangular groove, the magnetic fluid 231 and the second bracket 12 are matched to form a knife-edge sealing structure.

Of course, another embodiment not shown in the drawings may be adopted, in which the upper surface of the metal gasket 234, the surface of the second bracket 12 and the surface of the magnetic fluid 231 are provided with triangular recesses, and the lower surface of the metal gasket 234 on the lower surface of the T-shaped magnetic fluid fixing flange 233 is provided with triangular protrusions matching with the triangular recesses.

Specifically, the metal gasket 234 is made of copper, which is flexible and can fill up irregularities on the sealing surface, and the copper gasket is easy to process and can be produced in any specification and type.

In this embodiment, as shown in fig. 4 and 5, the transmission module 22 includes a second bracket 222 and a rotary shaft 221, and an end of the second bracket 222 away from the second reaction table 21 is screw-engaged with an end of the rotary shaft 221, so that the second bracket 222 can receive the rotation of the driving member 25.

In one embodiment, as shown in FIG. 4, an end of the second bracket 222 away from the second reaction table 21 is provided with an internal thread, and an end of the rotation shaft 221 is provided with an external thread matching with the internal thread.

In another embodiment, as shown in FIG. 5, an end of the second support 222 away from the second reaction table 21 is provided with an external thread, and an end of the rotation shaft 221 is provided with an internal thread matching with the external thread.

In this embodiment, as shown in fig. 4 and 5, in order to prevent the gas from remaining when the reaction chamber is evacuated, a through hole 224 is formed in a screw hole space 223 formed by screwing the second holder 222 and the rotating shaft 221, and the screw fitting of the second holder 222 and the rotating shaft 221 may be a male screw of the second holder 222 and a female screw of the rotating shaft 221, or a female screw of the second holder 222 and a male screw of the rotating shaft 221.

In this embodiment, as shown in fig. 6 and 7, a spring connection 225 is provided between the second bracket 222 and the rotation shaft 221, and the spring 225 is always kept in a tensed state, so that unnecessary errors caused by gravity and thread pitch when the height of the second elevating system is changed can be effectively avoided.

In one embodiment, as shown in fig. 6, the spring 225 is disposed in a screw hole space 223 formed by the matching of the internal thread of the second bracket 222 and the external thread of the rotating shaft 221 (here, one side of the screw hole space 223 is cut away for convenience of illustration), and two ends of the spring 225 respectively abut against the second bracket 222 and the rotating shaft 221, and are in a tension state.

In another embodiment, as shown in fig. 7, the spring 225 abuts between the second bracket 222 and the rotation shaft 221, and is sleeved on the rotation shaft thread, and the spring 225 is in a tension state.

In an embodiment not shown, the spring 225 is disposed in a screw hole space 223 formed by the external thread of the second bracket 222 and the internal thread of the rotating shaft 221, and both ends of the spring 225 respectively abut against the second bracket 222 and the rotating shaft 221 and are in a tensioned state.

In this embodiment, as shown in fig. 1 and 8, the transmission module 22 further includes a limiting device, the limiting device includes a limiting ring 226 fixed on the first lifting system by a connecting bracket 229, the limiting ring 226 is provided with a limiting protrusion 227, and the limiting protrusion 227 is matched with a limiting groove 228 on the second bracket 222.

In specific implementation, the magnetic fluid 231 drives the rotating shaft 221 to rotate, due to the existence of the limiting protrusion 227 for limiting the rotation of the second support 222, and then the limiting groove 228 on the second support 222 is matched, the second support 222 will not rotate any more, and moves up and down along the limiting groove 228, that is, the limiting device converts the rotation motion of the second support 222 into up and down movement along the limiting groove 228, and then the second support 222 drives the second reaction platform 21 to move up and down, so that the height change of the second reaction platform 21 is realized. Without the limiting device, the second support 222 directly rotates with the rotation of the rotation shaft 221 without moving up and down.

It should be noted that the limiting device may be fixed to the first reaction table 11 or the first support 12.

In this embodiment, the second lift system has a range of motion of 0-20 millimeters. This is because in the MPCVD method of growing diamond, the growth height of diamond is generally less than 20 mm.

The invention also provides equipment comprising the secondary lifting system for chemical vapor deposition.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

For convenience of description, spatially relative terms such as "above … …", "above … …", "above … …", "above", and the like, are used to describe the spatial relationship of parts and structures in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

It is to be understood that the above-described embodiments are only some, but not all embodiments of the present invention. The invention is not limited to the foregoing embodiments. Rather, the embodiments of the invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof, and the invention extends to any novel feature or any novel combination of features disclosed in this specification. It is intended that the specification be considered as exemplary only, with a true scope of the invention being indicated by the following claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. It will be apparent to those skilled in the art that other variations and modifications may be made in the invention without departing from the spirit and scope of the invention as defined in the following claims. All obvious changes and modifications of the present invention are within the scope of the present invention.

In addition, although the present specification describes embodiments, not every embodiment includes only one independent technical solution, and those skilled in the art should take the description as a whole, and technical solutions in the embodiments may be appropriately combined to form other embodiments that may be understood by those skilled in the art.

Claims

1. A two-stage lift system for chemical vapor deposition, comprising:

the first lifting system comprises a first reaction platform, a first support, a reaction chamber chassis, a screw rod, a vacuum corrugated pipe, a movable disc and a fixed disc, wherein the first reaction platform is arranged on the first support, the first support penetrates through the reaction chamber chassis and is fixedly connected with the movable disc, two ends of the vacuum corrugated pipe are respectively and fixedly connected with the reaction chamber chassis and the movable disc, one end of the screw rod is movably connected with the reaction chamber chassis, the other end of the screw rod penetrates through the fixed disc, and the movable disc is sleeved on the screw rod;

and the second lifting system is fixedly arranged in the first support and can move up and down along with the first lifting system.

2. The secondary lifting system for chemical vapor deposition according to claim 1, wherein the second lifting system comprises a second reaction table, a transmission module, a magnetic fluid sealing module and a driving member which are arranged in sequence; and a driving part fixing plate fixed with the driving part through bolts is arranged on the driving part, and the driving part fixing plate is fixed with the magnetic fluid sealing module through bolts.

3. The secondary lifting system for chemical vapor deposition according to claim 2, wherein the magnetic fluid sealing module comprises a magnetic fluid, a magnetic fluid nut matched with the external thread of the magnetic fluid, and a T-shaped magnetic fluid fixing flange, the T-shaped magnetic fluid fixing flange is arranged between the magnetic fluid and the second support in a penetrating manner, the magnetic fluid nut is used for sealing the magnetic fluid and the T-shaped magnetic fluid fixing flange, and the T-shaped magnetic fluid fixing flange is fastened with the second support through bolts.

4. The secondary lifting system for chemical vapor deposition of claim 3, wherein the magnetic fluid sealing module further comprises metal gaskets respectively arranged between the T-shaped magnetic fluid fixing flange and the magnetic fluid and the second support, and the sealing is in a knife edge sealing manner.

5. The two-stage lift system for chemical vapor deposition of claim 2, wherein the transmission module comprises a second bracket and a rotating shaft, and an end of the second bracket remote from the second reaction stage is in threaded engagement with an end of the rotating shaft.

6. The secondary lifting system for chemical vapor deposition according to claim 5, wherein a screw hole gap formed by the threaded fit of the second support and the rotating shaft is provided with a through hole to prevent gas residue during the vacuum pumping of the reaction chamber.

7. The secondary lift system for chemical vapor deposition of claim 5, wherein a spring connection is provided between the second support and the rotating shaft, the spring being maintained in tension at all times.

8. A secondary lifting system for chemical vapor deposition according to claim 2, wherein the transmission module further comprises a limiting device, the limiting device comprises a limiting ring fixed on the first lifting system by a connecting bracket, the limiting ring is provided with a limiting protrusion, and the limiting protrusion is matched with a limiting groove on the second bracket.

9. The two-stage lift system for chemical vapor deposition of claims 1-8, the second lift system having a range of height movement of 0-20 millimeters.

10. An apparatus, comprising: the secondary lift system for chemical vapor deposition as recited in any one of claims 1-9.