Chemical vapor deposition furnace with built-in electromagnetic field

Abstract

The chemical vapor deposition furnace with the built-in electromagnetic field comprises a furnace body, a heat preservation layer arranged in the furnace body, a heater arranged in the furnace body and an external power source electrically connected with the heater, an isolation barrel is arranged on the inner side of the heat preservation layer, and the heater is arranged between the isolation barrel and the heat preservation layer. The heater is arranged to be in a spiral shape surrounding the isolation cylinder, and the external power source is a medium-high frequency alternating current power source. The spiral heater is arranged in the furnace body, the isolation barrel is arranged in the center of the spiral heater, a workpiece is just located in the spiral heater, an external power source is arranged to be a medium-high-frequency alternating-current power source, and on one hand, the heater can emit heat to provide a heat source for the workpiece; and on the other hand, the heater can generate an alternating electromagnetic field which directly acts on the workpiece, so that the workpiece is self-heated, and the heating efficiency of the equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide semiconductors, and in particular to a chemical vapor deposition furnace with a built-in electromagnetic field. Background Art

[0002] The chemical vapor infiltration (CVI) process is a coating process that deposits coatings into the internal space of a porous preform under controlled conditions. The process is to place the preform in a special CVI furnace, heat it to the required temperature under vacuum, and introduce a precursor gas composed of a specific ratio to pyrolyze it into different charged ions and deposit them on the pore surface to fill the pores in the preform. Since the matrix prepared by CVI is tightly combined with the preform fiber and the structure thickness is adjustable, it is the preferred method for preparing high-performance carbon-carbon, carbon-ceramic and other composite materials.

[0003] At present, the commonly used CVI processes include isothermal CVI (ICVI), differential pressure CVI, thermal gradient CVI (TGCVI), forced flow CVI (FCVI), direct heating CVI (HCVI), etc., and electromagnetic field CVI (ECVI) introduces electromagnetic field on the basis of ICVI. The process gas produces beneficial intermediate phase charged ions under hot conditions. The electromagnetic field can greatly promote the adsorption of the workpiece to be deposited and capture the intermediate phase charged particles, so that the deposition efficiency is accelerated and the preparation cycle of the composite material is shortened. It is a low-cost and fast deposition CVI technology with great application prospects.

[0004] At present, chemical vapor deposition furnaces generally use resistance heating or medium-frequency induction heating. In a chemical vapor deposition furnace with resistance heating, the resistance heater is designed into a tubular, rod-shaped, or special-shaped shape according to the size of the deposition area, and the workpiece is directly heated by the heat radiation of the heater. There are two ways to introduce an electromagnetic field into the furnace: one is to add an external magnetic field to the heater or even the outside of the furnace shell, otherwise the magnetic induction device is easily melted by the high temperature in the furnace; but this magnetic field is far away from the deposition chamber, and the magnetic field has a relatively limited effect on the movement of charged ions. The second is to use the workpiece itself as a heating element and use the alternating current passing through the workpiece to generate an alternating magnetic field, but this method is not suitable for workpieces with complex shapes. The magnetic field generated by complex-shaped workpieces has an abnormal shape and is not necessarily conducive to the directional movement of charged particles; and the number of furnaces installed per furnace is small, and the production efficiency is low.

[0005] In a medium frequency induction heating deposition furnace, an induction coil arranged outside the insulation layer generally generates an alternating magnetic field under the action of alternating current, which generates an induced current to heat the induction crucible inside the insulation layer in the furnace body, and transfers heat to the workpiece through the crucible radiation. This type of induction coil is mostly wound with a hollow copper tube, and cooling water is passed through the inside; this type of induction coil heating device cannot be directly arranged inside the furnace body, otherwise it will be melted and damaged by the high temperature in the furnace. The magnetic field generated by this induction coil still needs to pass through the insulation layer and the induction crucible, and the intensity of the induced electromagnetic field is weakened, and the effect on the movement of charged ions is also limited. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the heater in the chemical vapor deposition furnace in the prior art cannot be directly arranged on the inner side of the insulation layer of the furnace body, and on the other hand, the magnetic field generated by the heater is far away from the workpiece. A chemical vapor deposition furnace with a built-in electromagnetic field is provided, which can generate an electromagnetic field on the inner side of the insulation layer.

[0007] The technical solution to the technical problem of the present invention is: constructing a chemical vapor deposition furnace with a built-in electromagnetic field, including a furnace body, an insulation layer arranged in the furnace body, a heater arranged in the furnace body, and an external power supply electrically connected to the heater, an isolation tube is provided on the inner side of the insulation layer, the heater is arranged between the isolation tube and the insulation layer, the heater is arranged in a spiral shape that surrounds the isolation tube inside, and the external power supply is a medium or high frequency AC power supply.

[0008] Furthermore, an annular receiving cavity is provided between the isolation tube and the heat-insulating layer, and the spiral heater is arranged in the annular receiving cavity, so that the spiral heater can be easily installed.

[0009] Furthermore, a preset distance is provided between the heater and the thermal insulation layer to prevent the thermal insulation layer from being too close to the heater and causing excessively strong magnetic induction heating, which would cause the thermal insulation layer to melt and fail.

[0010] Furthermore, the heater is a resistance heater made of graphite or a carbon-carbon composite material integrally formed.

[0011] Furthermore, the insulation layer includes an intermediate insulation tube arranged on the inner wall of the furnace body, an upper insulation cover arranged on the top of the intermediate insulation tube and a lower insulation cover arranged on the bottom of the intermediate insulation tube, and the isolation tube is arranged between the upper insulation cover and the lower insulation cover.

[0012] Furthermore, a workpiece support platform is provided at the center of the isolation cylinder located at the lower insulation cover.

[0013] Furthermore, the workpiece support table is made of a porous support plate, so that the process gas can enter the deposition area from the bottom of the furnace body, and be evenly distributed through the porous support plate and then deposited on the workpiece surface, ensuring uniform deposition thickness on the workpiece surface.

[0014] Furthermore, air inlet nozzles connected to an external process gas station are evenly distributed at the bottom of the furnace body, and the air inlet nozzles pass through the lower insulation cover and are connected to the bottom of the workpiece support platform.

[0015] Furthermore, the upper insulation cover is provided with an exhaust hole connected to an external exhaust gas treatment system.

[0016] Furthermore, the side wall of the furnace body is provided with terminal posts, and the terminal posts are electrically connected to the heater and the external power supply respectively, so as to facilitate wiring.

[0017] The chemical vapor deposition furnace with built-in electromagnetic field described in the present invention has the following beneficial effects: by setting a spiral heater in the furnace body and setting the isolation tube at the center of the spiral heater, the workpiece is located exactly inside the spiral heater, and the external power supply is set to a medium-high frequency AC power supply, which can make the heater generate heat to provide a heat source for the workpiece on the one hand; on the other hand, the heater can generate an alternating electromagnetic field, which directly acts on the workpiece, so that the workpiece self-heats and improves the heating efficiency of the equipment. In addition, the heater is directly set between the isolation tube and the insulation layer, and the alternating electromagnetic field it generates is closer to the workpiece located in the isolation tube, so that the intermediate phase charged ions can be quickly adsorbed on the surface of the workpiece under the action of the magnetic field, thereby improving the deposition speed and shortening the preparation cycle of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a schematic structural diagram of a preferred embodiment of a chemical vapor deposition furnace with a built-in electromagnetic field according to the present invention. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] It should also be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0022] like Figure 1 As shown, in a preferred embodiment of the chemical vapor deposition furnace with a built-in electromagnetic field described in the present invention, it mainly includes a furnace body 10, an insulation layer 20, a heater 30 and an external power supply 40. The insulation layer is arranged in the furnace body, and the insulation layer is preferably arranged to include an intermediate insulation tube 21, an upper insulation cover 22 and a lower insulation cover 23. Among them, the intermediate insulation tube 21 is arranged on the inner side of the furnace body 10 and is close to the inner wall of the furnace body, the upper insulation cover 22 is arranged on the top of the intermediate insulation tube 21, and the top opening of the intermediate insulation tube 21 is blocked, and the lower insulation cover 23 is arranged at the bottom of the intermediate insulation tube 21, and the bottom opening of the intermediate insulation tube 21 is blocked. In this way, the intermediate insulation tube 21 and the upper and lower insulation covers 22 and 23 are combined to form a hollow area inside it to ensure that the heat in the hollow area is not easy to dissipate.

[0023] It is preferred to arrange an isolation tube 1 on the inner side of the insulation tube, and arrange the heater 30 between the isolation tube 1 and the insulation layer 20 to prevent the deposition product from contaminating the heater. The isolation tube 1 can be made of materials such as graphite or carbon-carbon composite materials or ceramics. Specifically, an annular receiving chamber 24 can be arranged between the isolation tube 1 and the insulation layer 20, and the heater 30 can be arranged in the annular receiving chamber 24. It is best to arrange an annular groove on the inner side of the middle insulation tube 21, and seal the isolation tube 1 at the open end of the annular groove, so as to form the above-mentioned annular receiving chamber 24 between the isolation tube 1 and the middle insulation tube 21. During installation, the heater 30 is arranged in the annular groove of the middle insulation tube 21, and then the isolation tube 1 is inserted into the inner side of the middle insulation tube 21 and the open end of the annular groove is sealed, which is very convenient for assembly and disassembly.

[0024] It is preferred to set a preset distance D between the heater 30 and the inner side wall of the intermediate insulation tube 21, and the preset distance D is far enough to ensure that the magnetic field formed by the heater 30 during operation is not sufficient to form an induced current in the intermediate insulation tube 21, or the heat generated by the induced current in the intermediate insulation tube is not sufficient to damage the intermediate insulation tube or affect the normal operation of the intermediate insulation tube.

[0025] In this preferred embodiment, the heater 30 is preferably set to a spiral shape, and the spiral heater surrounds the isolation tube 1 inside it, and at the same time, the external power supply 40 is set to a medium-high frequency AC power supply. When the medium-high frequency AC power passes through the spiral heater 30, an alternating electromagnetic field T is formed around the heater 30, and the magnetic field T directly acts on the workpiece located at the center of the isolation tube 1, which can not only increase the heating speed of the workpiece, but also promote the rapid adsorption of the intermediate phase charged ions on the surface of the workpiece, thereby increasing the deposition speed. It is preferred to set the spiral heater 30 to be made of graphite or carbon-carbon composite material in one piece, which can ensure that the heater 30 will not fail due to high temperature in the furnace body 10 on the one hand, and on the other hand, it can improve the heating efficiency of the heater 30.

[0026] In this preferred embodiment, a workpiece support platform 11 is preferably provided at the center of the isolation cylinder 1 on the top of the lower insulation cover 23 to support the workpiece to be deposited. It is best to set the workpiece support platform 11 to be made of a porous receiving plate, so that the process gas introduced from the bottom can be evenly divided by the porous receiving plate and deposited on the workpiece surface to ensure uniform deposition thickness on the workpiece surface.

[0027] Preferably, air inlet nozzles 13 connected to the external process gas station 12 are evenly arranged at the bottom of the furnace body 10, and the air inlet nozzles 13 are connected to the bottom of the workpiece support platform 11 through the lower insulation cover 23. Preferably, exhaust holes 22a are arranged at the upper insulation cover 22, and the exhaust holes 22a are connected to the external exhaust gas treatment system 14 so that the exhaust gas can be discharged in time. Preferably, terminal posts 15 are arranged on the side wall of the furnace body, and the terminal posts 15 are electrically connected to the heater 30 and the external power supply 40 respectively, so as to facilitate wiring.

[0028] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work, any modifications, equivalent substitutions, improvements, etc. made should be included in the protection scope of the present invention.

Claims

1. A chemical vapor deposition furnace with a built-in electromagnetic field, comprising a furnace body, a heat preservation layer arranged in the furnace body, a heater arranged in the furnace body, and an external power supply electrically connected to the heater, characterized in that: An isolation tube is provided inside the insulation layer, the heater is provided between the isolation tube and the insulation layer, the heater is provided in a spiral shape surrounding the isolation tube inside, and the external power source is a medium-high frequency AC power source.

2. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 1, characterized in that: An annular receiving cavity is provided between the isolation tube and the heat-insulating layer, and the spiral heater is arranged in the annular receiving cavity.

3. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 2, characterized in that: A preset distance is arranged between the heater and the heat-insulating layer.

4. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 1, characterized in that: The heater is a resistance heater made of graphite or carbon-carbon composite material integrally formed.

5. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 1, characterized in that: The insulation layer includes an intermediate insulation tube arranged on the inner wall of the furnace body, an upper insulation cover arranged on the top of the intermediate insulation tube, and a lower insulation cover arranged on the bottom of the intermediate insulation tube, and the isolation tube is arranged between the upper insulation cover and the lower insulation cover.

6. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 5, characterized in that: A workpiece support platform is provided at the center of the isolation cylinder located at the lower insulation cover.

7. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 6, characterized in that: The workpiece supporting platform is made of a porous material bearing plate.

8. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 7, characterized in that: The bottom of the furnace body is evenly provided with air inlet nozzles connected to an external process gas station, and the air inlet nozzles pass through the lower insulation cover and are connected to the bottom of the workpiece support platform.

9. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 5, characterized in that: The upper insulation cover is provided with an exhaust hole connected to an external exhaust gas treatment system.

10. The chemical vapor deposition furnace with built-in electromagnetic field according to claim 1, characterized in that: The side wall of the furnace body is provided with connecting posts, and the connecting posts are electrically connected to the heater and the external power supply respectively.

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