Silicon carbide crystal deposition device and silicon carbide crystal preparation method

Abstract

The present invention belongs to the technical field of semiconductor equipment, and specifically relates to a silicon carbide crystal deposition device and a silicon carbide crystal preparation method. The raw material gas is first mixed in a feed mixing chamber of a preheating mixing module and the mixed gas in a heat exchange chamber is preheated by heat exchange with the tail gas of the deposition chamber, thereby preheating the raw material gas to a temperature close to the deposition temperature in a reduction furnace, reducing the temperature gradient between the feed position and other areas in the reduction furnace, so that the raw material can enter the deposition chamber at a low temperature and quickly start reaction and deposition on the surface of a carrier with a higher temperature, thereby improving the crystal deposition efficiency and realizing the recycling of the tail gas; and by arranging a light source catalyst and an active metal layer, the material molecules are pretreated by the dual catalysis of light and active metal, which is beneficial to improving the material molecule energy, reducing the activation energy of the reaction, and promoting the reaction to proceed at a low temperature, so that the material can react quickly and fully, thereby helping to improve the deposition efficiency of the silicon carbide crystal.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor equipment, and in particular relates to a silicon carbide crystal deposition device and a silicon carbide crystal preparation method. Background Art

[0002] The current preparation methods of high-purity silicon carbide for semiconductors mainly include self-propagating method and CVD chemical vapor deposition method. Among them, the reaction temperature of preparing silicon carbide by self-propagating method is 1800~2000℃. The reaction temperature is high and the equipment requirements are high. At the same time, the output of a single furnace is low and the product quality is poor. The deposition temperature of CVD chemical vapor deposition method is lower than that of self-propagating method, the output of a single furnace is large, and the purity is high. It is a more competitive method. At present, relevant patents have published a method of preparing silicon carbide by vapor deposition of methylchlorosilane and hydrogen in a CVD reduction furnace. The deposition temperature is 1200~1600℃. Although the temperature is lower than that of the self-propagating method, it is still over a thousand degrees. Under high temperature conditions, the raw materials need to be fully heated to fully react, resulting in low final deposition efficiency and low raw material utilization.

[0003] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or known technology. Summary of the invention

[0004] The purpose of the present invention is to provide a silicon carbide crystal deposition device and a silicon carbide crystal preparation method to overcome the problem that the existing silicon carbide deposition device has insufficient reaction due to high deposition temperature, thereby affecting the deposition efficiency.

[0005] In order to achieve the above-mentioned objectives, in the first aspect, an embodiment of the present invention provides a silicon carbide crystal deposition device, comprising: a preheating mixing module, a photocatalytic reaction module and a deposition chamber arranged in sequence; the preheating mixing module comprises a feed mixing chamber and a heat exchange chamber surrounding the outside of the feed mixing chamber, one end of the mixing chamber is used to be connected to each feed pipeline, and the other end of the mixing chamber is connected to the feed port of the photocatalytic reaction module, the heat exchange chamber is connected to the exhaust pipeline of the deposition chamber through a circulation pipeline, so as to introduce the exhaust gas discharged from the deposition chamber into the mixing chamber to preheat the mixed material; the discharge port of the photocatalytic reaction module is connected to the air inlet pipeline of the deposition chamber, and the photocatalytic reaction module is provided with an activation light source and an activation metal coating along the material flow direction, which are used to activate and catalytically decompose the mixed material preheated by the preheating mixing module, so as to improve the activity of the material entering the deposition chamber.

[0006] Optionally, the photocatalytic reaction module includes: an activation cylinder; one end of the activation cylinder is connected to the feed mixing chamber via a first connecting pipe, and the other end of the activation cylinder is connected to the air inlet pipe of the deposition chamber via a second connecting pipe; the activation light source is arranged in the activation cylinder, the length extension direction of the activation light source is parallel to the central axis direction of the activation cylinder, and the activated metal coating is arranged on the inner side wall of the activation cylinder; the activation light source is fixed to the inside of the activation cylinder through a support frame, and the length extension of the activation light source overlaps with the central axis of the activation cylinder.

[0007] Optionally, the activated metal coating covers the inner side wall of the activated cylinder; and the side of the activated metal coating facing the activated light source has a surface structure with alternating concave and convex surfaces.

[0008] Optionally, the activated metal coating is distributed in a serrated or wavy shape on the side facing the activating light source, and the extension direction of the serrated or wavy shape is consistent with the length extension direction of the activating light source; and / or, the activated metal coating includes one metal or a mixture of multiple metals selected from platinum, titanium, nickel, and silver.

[0009] Optionally, the activation light source is ultraviolet light, and the wavelength of the ultraviolet light is 100nm~400nm.

[0010] Optionally, the temperature in the mixing chamber is 200° C. to 300° C. lower than the temperature in the deposition chamber.

[0011] Optionally, the silicon carbide crystal deposition device also includes: a silicon source feed pipeline, a carbon source feed pipeline and a carrier gas feed pipeline, the silicon source feed pipeline, the carbon source feed pipeline and the carrier gas feed pipeline are respectively connected to one end of the mixing chamber, and are respectively used to introduce the carbon source, silicon source and carrier gas into the mixing chamber to perform mixed preheating in the mixing chamber; the feed flow rates of the silicon source feed pipeline and the carbon source feed pipeline are 0.5~5m / s, and the mass ratio of the silicon source, carbon source and carrier gas is 1:(0.4~1):(1~5).

[0012] Optionally, the deposition rate of the deposition chamber is 1 mm / h~10 mm / h.

[0013] In a second aspect, an embodiment of the present invention further provides a method for preparing a silicon carbide crystal, based on the silicon carbide crystal deposition device as described in the first aspect, comprising:

[0014] The carbon source, the silicon source and the carrier gas are respectively introduced into the preheating mixing module for mixing and preheating;

[0015] The mixed material after mixing and preheating enters the photocatalytic reaction module for photocatalytic reaction and metal activation reaction;

[0016] The activated mixed material is transported to a deposition chamber for a crystal deposition reaction; wherein the reaction temperature in the deposition chamber is 200°C to 300°C higher than the preheating temperature of the mixture.

[0017] Optionally, the temperature of the deposition chamber is 500° C. to 800° C., and the pressure is 20 to 500 kPa.

[0018] Optionally, the activation light source is ultraviolet light, and the wavelength of the ultraviolet light is 100nm~400nm; the intensity power range of the activation light source is 10~300KWh; the mixed and preheated mixed material enters the photocatalytic reaction module for photocatalytic reaction and metal activation reaction, and the material residence time is 30~600s.

[0019] Optionally, the feed flow rates of the silicon source feed pipeline and the carbon source feed pipeline are 0.5~5m / s, and the mass ratio of the silicon source, carbon source and carrier gas is 1:(0.4~1):(1~5); the feed amount of the silicon source is 1~400kg / h, and the feed amount of the carbon source is 1~400kg / h; the deposition rate of the deposition chamber is 1mm / h~10mm / h.

[0020] The embodiments of the present invention have at least the following technical effects:

[0021] The silicon carbide crystal deposition device and silicon carbide crystal preparation method provided by the embodiment of the present invention, by first mixing the raw material gas in the feed mixing chamber of the preheating mixing module and using the tail gas of the deposition chamber to heat exchange and preheat the mixed gas in the heat exchange chamber, the raw material gas is preheated to a temperature close to the deposition temperature in the reduction furnace, the temperature difference is reduced, and the temperature gradient between the feed position and other areas in the reduction furnace is reduced, so that the raw material can enter the deposition chamber at a low temperature and quickly start to react and deposit on the carrier surface with a higher temperature, thereby improving the crystal deposition efficiency and realizing the recycling of the tail gas; and by providing a light source catalyst and an active metal layer, the material molecules are pretreated by the dual catalysis of light and active metal, which is beneficial to improve the material molecule energy and reduce the activation energy of the reaction, further improve the gas activity of the preheated raw material gas that is easy to react quickly, and further improve the material molecule energy, reduce the reaction activation energy, and promote the reaction to be carried out at a low temperature, so that the material can react quickly and fully after entering the deposition chamber, which is beneficial to improve the deposition efficiency of the silicon carbide crystal and improve the raw material utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the overall structure of a silicon carbide crystal deposition device provided in an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the specific structure of a photocatalytic reaction module of a silicon carbide crystal deposition device provided in an embodiment of the present invention;

[0025] Figure 3 A flow chart of a method for preparing silicon carbide crystal provided in an embodiment of the present invention.

[0026] Reference numerals:

[0027] 100-preheating mixing module; 101-silicon source feed pipeline; 102-carrier gas feed pipeline; 103-carbon source feed pipeline; 110-feed mixing chamber; 120-heat exchange chamber;

[0028] 200-photocatalytic reaction module; 210-activation cylinder; 210a-convex structure; 220-activation space;

[0029] 300-Activation light source;

[0030] 400-activated metal plating;

[0031] 500-deposition chamber; 510-intake pipe; 520-exhaust pipe; 530-gate-shaped rod structure;

[0032] 600-first connecting pipeline;

[0033] 700 - second connecting pipeline;

[0034] 800-Circulation line. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as here.

[0037] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0038] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0040] The first aspect, such as Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a silicon carbide crystal deposition device, comprising: a preheating mixing module 100, a photocatalytic reaction module 200 and a deposition chamber 500 arranged in sequence, wherein the deposition chamber 500 (also called a reduction furnace) is the main reaction chamber for silicon carbide crystal deposition, and the deposition chamber 500 is provided with inlet and outlet pipelines and a rod connected to an electrode, and the material reacts in the deposition chamber 500 and is deposited on the rod.

[0041] Specifically, the preheating mixing module 100 is mainly used for mixing and preheating raw materials, and preheating the mixed materials in advance, so as to facilitate low-temperature rapid deposition in the deposition chamber 500. The preheating mixing module 100 includes a feed mixing chamber 110 and a heat exchange chamber 120, and the heat exchange chamber 120 is surrounded by the outside of the feed mixing chamber 110. Among them, one end of the mixing chamber is used to connect with each feed pipeline (including a carbon source feed pipeline 103, a silicon source feed pipeline 101 and a carrier gas feed pipeline 102), so that the materials from each feed pipeline enter the mixing chamber for mixing, and the heat exchange chamber 120 is connected to the exhaust pipeline 520 of the deposition chamber 500 through the circulation pipeline 800, so as to introduce the exhaust gas discharged from the deposition chamber 500 into the mixing chamber to preheat the mixed material, so as to realize the secondary utilization of the exhaust gas and preheat the material at the same time.

[0042] Furthermore, the other end of the mixing chamber is connected to the feed port of the photocatalytic reaction module 200 through the first connecting pipeline 600, so as to transport the mixed and preheated materials to the photocatalytic reaction module 200 for activation. The discharge port of the photocatalytic reaction module 200 is connected to the air inlet pipeline 510 of the deposition chamber 500 through the second connecting pipeline 700. The photocatalytic reaction module 200 is provided with an activated metal coating 400 and an activated light source 300 along the material flow direction, which are used to activate and catalytically decompose the mixed materials preheated by the preheating mixing module 100, so as to improve the activity of the materials entering the deposition chamber 500.

[0043] The silicon carbide crystal deposition device provided by the embodiment of the present invention preheats the raw material gas to a temperature close to the deposition temperature in the reduction furnace, reduces the temperature difference, and reduces the temperature gradient between the feed position and other areas in the reduction furnace (the existence of the temperature gradient, i.e., the temperature difference, affects the smooth progress of the deposition reaction), so that the raw material can enter the deposition chamber 500 at a low temperature and quickly start the reaction and deposition on the carrier surface with a higher temperature, thereby improving the crystal deposition efficiency and also realizing the recycling of the tail gas; and by providing a light source catalysis and an active metal layer, the material molecules are pretreated by the dual catalysis of light and active metals, which is conducive to improving the energy of the material molecules, reducing the activation energy of the reaction, and promoting the reaction to proceed at a low temperature, that is, the present invention first pre-mixes and preheats the material, and then improves the activity of the raw material through light source catalysis and active metal layer activation, which is conducive to reducing the deposition temperature, improving the deposition efficiency, and improving the utilization rate of the raw material.

[0044] In some embodiments, continue to refer to Figure 1 and Figure 2The photocatalytic reaction module 200 includes: an activation cylinder 210, the interior of the activation cylinder 210 is a hollow structure, thereby forming a cylindrical activation space 220; wherein, one end of the activation cylinder 210 is connected to the feed mixing chamber 110 through a first connecting pipe 600, and the other end of the activation cylinder 210 is connected to the air intake pipe 510 of the deposition chamber 500 through a second connecting pipe 700.

[0045] Specifically, the activation light source 300 is arranged in the activation cylinder 210, and the length extension direction of the activation light source 300 is parallel to the central axis direction of the activation cylinder 210, which is more conducive to increasing the time of the photocatalytic reaction and improving the photocatalytic effect. The activation metal coating 400 is arranged on the inner wall of the activation cylinder 210, which minimizes the impact on the fluidity of the material, and the contact area of ​​the metal activation reaction is large, which is conducive to improving the activation effect. It should be noted that one or more activation light sources 300 can be set according to specific needs, and there is no specific limitation in this embodiment. Optionally, the activation light source 300 can also be arranged inside the activation cylinder 210 perpendicular to the material flow direction, and multiple activation light sources 300 can be arranged at intervals along the axial direction of the activation cylinder 210 to improve the activation effect.

[0046] Optionally, the activation cylinder 210 is made of stainless steel or other materials, which is resistant to high temperature and high pressure. The activated metal coating 400 includes one metal or a mixture of multiple metals selected from platinum, titanium, nickel, and silver. The raw material contacts the surface of the activated metal coating 400 for catalysis, thereby increasing the activity of the raw material and synergizing with photocatalysis to promote the dissociation of gas molecules.

[0047] Optionally, the activating light source 300 is ultraviolet light, and the wavelength of the ultraviolet light is 100nm~400nm. The ultraviolet light emitted by the activating light source 300 irradiates raw materials such as silane and ethylene. The ultraviolet light excites the silane molecules, and the silane, ethylene or propyne molecules absorb light energy of a specific wavelength, which leads to the breaking of chemical bonds, causing them to absorb photons and transition to an excited state, and then to be excited to a high-energy state, thereby promoting the dissociation of the molecules, making the molecules in an ionic state, and improving the activity of the material. Combined with the mixed preheating of the materials, the purpose of lowering the deposition temperature is achieved.

[0048] Optionally, the shorter the wavelength of light, the greater the energy of the photon. Within this wavelength range, ultraviolet light with a wavelength of 150~250nm is preferred. At this time, the photon energy irradiates the raw material, and the photon energy is greater, which is more conducive to adapting to the high flow rate of the raw material gas flow, that is, it is beneficial to control the residence time of the molecules to be shorter at a high flow rate, promote the raw material molecules to process the excited state, and be in a high activity, thereby increasing the deposition rate.

[0049] Optionally, the wavelength and intensity of the activation light source 300 in this embodiment can be set according to actual needs to control the residence time of the material in the reactor. The preferred residence time is 30 to 600 seconds, which can be adjusted by the length and volume of the activation cylinder 210, the path length of the activated metal coating 400, the coverage area, the air flow velocity, the pipe diameter, etc.; if the residence time is lower than the above, the reaction gas is insufficiently activated, which affects the reaction rate entering the reactor and reduces the deposition rate; if the residence time is higher than the above, the reaction gas is over-activated, the residence time is too long, the possibility of deposition on the equipment is increased, the utilization rate of the raw materials is reduced, and the service life of the equipment is affected.

[0050] Optionally, the intensity of the photocatalytic light source can be adjusted dynamically, with a power range of 10~300KWh. When the power is too low, the light source intensity is weak, the propagation distance is short or the irradiation coverage area is small, and all materials cannot be effectively activated; while the increase in power will increase the intensity of the light source, the propagation and penetration performance of the light is good, and it can penetrate or cover a larger range of materials, irradiate and excite atoms, which is conducive to the full activation of the raw materials; and when the amount of raw materials is constant, continuing to increase the intensity of the light source will result in excess energy and waste, and the higher the better is not necessarily the case. Therefore, the power range of the photocatalytic light source is limited in this embodiment.

[0051] Optionally, the temperature in the mixing chamber is 200°C to 300°C lower than the temperature in the deposition chamber 500, so that the raw gas is not fully decomposed before entering the reduction furnace. For example, the temperature in the mixing chamber is generally 300°C to 500°C, and the temperature in the deposition chamber 500 is generally 500°C to 800°C.

[0052] It is understandable that if the preheating temperature of the mixing chamber is too high, the reaction activity of the raw gas will be too high. Under treatments such as light excitation and catalyst catalysis, the activity of the raw gas will be too high, and the risk of deposition during the raw gas transportation process and contact with the furnace wall of the deposition chamber 500 will increase, which is not conducive to improving the raw material utilization rate. However, if the preheating temperature is too low, it will lead to insufficient raw gas activity and low heat utilization, which is not conducive to improving the raw material utilization rate under low temperature conditions of the reduction furnace. Therefore, the preheating temperature of the mixing chamber for the material needs to be controlled within the above-mentioned reasonable range.

[0053] Optionally, the activation light source 300 can be fixed inside the activation cylinder 210 through a support frame, and the length of the activation light source 300 extends to overlap with the central axis of the activation cylinder 210, so that the catalytic effect on materials flowing in all directions is more balanced.

[0054] In some embodiments, continue to refer to Figure 2The activated metal coating 400 covers the inner wall of the activation cylinder 210; the side of the activated metal coating 400 facing the activating light source 300 is an alternating concave and convex surface structure, which can increase the disturbance of the airflow, accelerate the collision of the raw material molecules and the irradiation of the light source, thereby promoting photocatalytic excitation, and at the same time increase the contact area with the raw material gas, thereby improving the activation effect of the activated metal coating.

[0055] Specifically, the inner wall of the activation cylinder 210 is provided with a plurality of continuously arranged protruding structures 210a, and the protruding structures 210a can be integrally formed with the inner wall of the activation cylinder 210, so that when the activated metal coating 400 is formed on the inner wall of the activation cylinder 210 by the plating process, since the thickness of the activated metal coating 400 is relatively thin, a concave-convex alternating surface structure is naturally formed on the inner wall of the activation cylinder 210. Optionally, the protruding structures 210a arranged on the inner wall of the activation cylinder 210 can be triangular pyramid structures, boss structures, or convex ball structures, and these protruding structures 210a can be arranged continuously or intermittently, which is not specifically limited in the embodiment of the present invention.

[0056] Optionally, the activated metal coating 400 is distributed in a zigzag or wavy shape on one side facing the activated light source 300, and the extending direction of the zigzag or wavy shape is consistent with the extending direction of the length of the activated light source 300. Figure 2 Taking the sawtooth structure as an example, the cross-sectional shape of the sawtooth structure along the airflow direction is a triangular cone structure, which is more conducive to further increasing the airflow disturbance, extending the airflow path, adjusting the residence time of the raw gas, and reflecting the ultraviolet light at multiple angles through the surface of the triangular cone to enhance the ultraviolet light activation effect, which is conducive to achieving rapid, sufficient and uniform activation of large-flow raw gas at low temperature and rapid deposition speed, thereby improving the catalytic effect.

[0057] In some embodiments, Figure 1 As shown, the silicon carbide crystal deposition device also includes: a silicon source feed pipeline 101, a carbon source feed pipeline 103 and a carrier gas feed pipeline 102. The silicon source feed pipeline 101, the carbon source feed pipeline 103 and the carrier gas feed pipeline 102 are respectively connected to one end of the mixing chamber, and are respectively used to introduce the carbon source, silicon source and carrier gas into the mixing chamber to perform mixing preheating in the mixing chamber.

[0058] In this embodiment, the silicon source and carbon source in the raw gas are separately controlled through different feed hooks. According to the needs of different stages, the usage ratio of the silicon source and the carbon source is accurately adjusted, and the ratio of silicon and carbon in the reactor is accurately controlled to meet the ratio adjustment of the carbon source and the silicon source in different reaction stages.

[0059] Optionally, the feed amount of silicon sources such as silane is 1~400kg / h, and the feed amount of carbon sources such as acetylene is 1~400kg / h; the ratio of the two is controlled by mass flow meters; the feed flow rates of the silicon source feed pipeline 101 and the carbon source feed pipeline 103 are 0.5~5m / s, and the mass ratio of the silicon source, the carbon source and the carrier gas is 1:(0.4~1):(1~5); by adjusting the large feed amount and high flow rate of the silicon source and the carbon source, sufficient raw material supply is provided for the realization of high deposition rate at low temperature in the reduction furnace.

[0060] Optionally, silane, disilane, trisilane, etc. having Si n H x-n The silicon source is the structural silicon hydrogen compound, and acetylene, propylene, etc. are used as the carbon source. After mixing with hydrogen, silicon carbide is deposited in the CVD reduction furnace. After the tail gas is filtered, the byproducts are hydrogen and a small amount of unreacted silicon source and carbon source. The byproducts enter the activated carbon pressure swing adsorption to purify the hydrogen. The purified hydrogen is reused, and the remaining byproducts enter the tail gas for incineration. Compared with the existing CVD deposition method, there is no bubbling leaching, hydrogen chloride recovery and other links, and the process flow is short.

[0061] Optionally, the mass ratio of silane to ethylene or propyne or both is 1:(0.4~1), so as to realize dynamic control of the carbon source and the carbon source ratio. Silane and the carbon source produce hydrogen when they are decomposed and deposited. Therefore, the by-product hydrogen can be directly utilized to participate in the reaction without the need to input a large amount of additional hydrogen (carrier gas). The ratio of silane to hydrogen in the feed is 1:1~5. Compared with the existing method, the amount of new hydrogen added to the system is greatly reduced. At the same time, the raw materials and by-products do not contain chlorine, so there is no corrosion to the system, thus avoiding system corrosion and the introduction of impurities.

[0062] Optionally, the deposition rate of the deposition chamber 500 is 1 mm / h~10 mm / h. By further improving the gas activity of the preheated raw gas that is easy to react quickly, the energy of the material molecules can be further increased, the reaction activation energy can be reduced, and the reaction can be carried out at a low temperature. In this way, the material can react quickly and fully after entering the deposition chamber, thereby achieving a high deposition rate at a low temperature in the silicon carbide crystal reduction furnace.

[0063] In some specific embodiments, the deposition rate using methylchlorosilane as a raw material is currently 0.5-1.0 mm / h;

[0064] The raw materials are directly deposited in the deposition chamber without preheating, light and active metal catalysis, and the deposition rate is 1.5~2.5mm / h;

[0065] The raw materials are preheated to 300-500°C, without light and active metal catalysis, and then enter the deposition chamber for deposition at a deposition rate of 2.5-4 mm / h.

[0066] The raw materials are preheated, photocatalyzed and catalyzed by active metals, and then enter the deposition chamber for deposition. The deposition rate is greater than 5 mm / h and less than 10 mm / h.

[0067] In some specific embodiments, the deposition chamber 500 of the silicon carbide crystal deposition device provided in the embodiment of the present invention is a bell-shaped reactor, and a gate-shaped rod structure 530 is arranged in the bell-shaped reactor, and the logarithm of the gate-shaped rod structure 530 is 4, 6, 12, 24, 36, etc. The temperature in the reactor is 500-800°C, and the pressure is 20-500kPa. At this temperature and pressure, the silicon source and the carbon source are decomposed and deposited on the deposition carrier to produce silicon carbide. At this low temperature, the raw materials such as silane and acetylene are coordinated through preheating, metal catalysis, and photocatalysis, and the decomposition temperature is much lower than the existing CVD method and self-propagating method using methylchlorosilane as raw material, and the decomposition efficiency is high, which can be up to 90% or more, and the raw material utilization rate is high. The decomposition rate is calculated by measuring the weight of silane entering the deposition path through a mass flow meter and converting it into the weight of silicon atoms. After the reaction is completed, the deposition furnace is turned on and the weight of solid silicon carbide is weighed. The weight is then subtracted from the weight of silicon in the raw silane to obtain the decomposition rate under different adjustments, as shown in Table 1.

[0068] Table 1 Comparison of decomposition rates under different conditions

[0069]

[0070] Furthermore, the tail gas after the reaction in the deposition chamber 500 of the silicon carbide crystal deposition device provided by the embodiment of the present invention is mainly hydrogen, and a small amount of unreacted silicon source and carbon source, as well as amorphous silicon solid particles, first enter the filtration system for gas-liquid separation, and then the hydrogen-containing tail gas enters the activated carbon pressure swing adsorption system, and the recovered hydrogen is reused as a raw material. The remaining materials enter the tail gas system for treatment.

[0071] It is understandable that the silicon carbide crystal deposition device provided by the embodiment of the present invention does not involve materials containing chlorine in the whole process during the silicon carbide crystal deposition process, which solves the problem of equipment defects caused by chlorine corrosion and the introduction of impurities by corrosion; at the same time, the raw material has a high decomposition efficiency in CVD, and only hydrogen needs to be simply recovered from the by-products, which reduces the steps of methylchlorosilane bubbling elution, distillation and purification, and the system process is short and the equipment requirements are low. Moreover, silane has a low boiling point and is easier to separate and purify than methylchlorosilane. Under the same conditions, the raw material purity is higher, which can effectively improve the product quality.

[0072] The second aspect is based on the same inventive concept. Figure 3 As shown, an embodiment of the present invention also provides a method for preparing silicon carbide crystals. Based on the silicon carbide crystal deposition device as described in the first aspect, the preparation method includes the following steps:

[0073] S100, introducing the carbon source, silicon source and carrier gas into a preheating mixing module respectively for mixing and preheating.

[0074] S200, the mixed and preheated mixed material enters the photocatalytic reaction module to undergo photocatalytic reaction and metal activation reaction.

[0075] S300, transporting the activated mixed material to a deposition chamber for crystal deposition reaction; wherein the reaction temperature in the deposition chamber is 200°C to 300°C higher than the preheating temperature of the mixture.

[0076] It should be noted that, since the silicon carbide crystal preparation method in this embodiment is based on the silicon carbide crystal deposition device in the aforementioned embodiment, the specific contents of the silicon carbide crystal deposition device will not be repeated.

[0077] Optionally, the temperature of the deposition chamber is 500° C. to 800° C., and the pressure is 20 to 500 kPa.

[0078] Optionally, the activation light source is ultraviolet light, and the wavelength of the ultraviolet light is 100nm~400nm; the intensity power range of the activation light source is 10~300KWh; the mixed and preheated mixed material enters the photocatalytic reaction module for photocatalytic reaction and metal activation reaction, and the material residence time is 30~600s.

[0079] Optionally, the feed flow rates of the silicon source feed pipeline and the carbon source feed pipeline are 0.5~5m / s, and the mass ratio of the silicon source, carbon source and carrier gas is 1:(0.4~1):(1~5); the feed amount of the silicon source is 1~400kg / h, and the feed amount of the carbon source is 1~400kg / h; the deposition rate of the deposition chamber is 1mm / h~10mm / h.

[0080] The method for preparing silicon carbide crystals provided in an embodiment of the present invention preheats the raw material gas to a temperature close to the deposition temperature in the reduction furnace, reduces the temperature difference, and reduces the temperature gradient between the feed position and other areas in the reduction furnace, so that the raw material can quickly start reaction and deposition on the carrier surface at a higher temperature when entering the deposition chamber at a low temperature, thereby improving the crystal deposition efficiency and also realizing the recycling of the exhaust gas; and by providing a light source catalysis and an active metal layer, the material molecules are pretreated by the dual catalysis of light and active metals, which is beneficial to improving the energy of the material molecules, reducing the activation energy of the reaction, and promoting the reaction to proceed at a low temperature. That is, the present invention first pre-mixes and preheats the material, and then improves the activity of the raw material through light source catalysis and active metal layer activation, which is beneficial to reducing the deposition temperature and improving the deposition efficiency.

[0081] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific conditions. In the description of this specification, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon carbide crystal deposition device, characterized in that: include: A preheating mixing module, a photocatalytic reaction module and a deposition chamber are arranged in sequence; The preheating mixing module includes a feed mixing chamber and a heat exchange chamber surrounded outside the feed mixing chamber, one end of the mixing chamber is used to connect with each feed pipeline, the heat exchange chamber is connected with the exhaust pipeline of the deposition chamber through a circulation pipeline, so as to introduce the exhaust gas discharged from the deposition chamber into the mixing chamber to preheat the mixed material, and the other end of the mixing chamber is connected with the feed port of the photocatalytic reaction module; The discharge port of the photocatalytic reaction module is connected to the air inlet pipeline of the deposition chamber. The photocatalytic reaction module is provided with an activation light source and an activation metal coating along the material flow direction, which are used to activate and catalytically decompose the mixed material preheated by the preheating mixing module, so as to improve the activity of the material entering the deposition chamber; The photocatalytic reaction module includes: an activation cylinder; one end of the activation cylinder is connected to the feed mixing chamber via a first connecting pipe, and the other end of the activation cylinder is connected to the air inlet pipe of the deposition chamber via a second connecting pipe; the activation light source is arranged in the activation cylinder, the length extension direction of the activation light source is parallel to the central axis direction of the activation cylinder, and the activated metal coating is arranged on the inner side wall of the activation cylinder; the activation light source is fixed to the inside of the activation cylinder through a support frame, and the length extension of the activation light source overlaps with the central axis of the activation cylinder.

2. The silicon carbide crystal deposition device according to claim 1, characterized in that: The activated metal coating covers the inner side wall of the activated cylinder, and the side of the activated metal coating facing the activated light source has a surface structure with alternating concave and convex portions.

3. The silicon carbide crystal deposition device according to claim 2, characterized in that: The activated metal coating is distributed in a zigzag or wavy shape on one side facing the activated light source, and the extending direction of the zigzag or wavy shape is consistent with the length extending direction of the activated light source; And / or, the activated metal coating layer includes one metal or a mixture of multiple metals selected from platinum, titanium, nickel and silver.

4. The silicon carbide crystal deposition device according to claim 1, characterized in that: The activation light source is ultraviolet light, and the wavelength of the ultraviolet light is 100nm~400nm; the temperature in the mixing chamber is 200℃~300℃ lower than the temperature in the deposition chamber; the intensity power range of the photocatalytic light source is 10~300KWh; the deposition rate of the deposition chamber is 1mm / h~10mm / h.

5. The silicon carbide crystal deposition device according to any one of claims 1 to 4, characterized in that: Also includes: A silicon source feed pipeline, a carbon source feed pipeline and a carrier gas feed pipeline, wherein the silicon source feed pipeline, the carbon source feed pipeline and the carrier gas feed pipeline are respectively connected to one end of the mixing chamber, and are respectively used to introduce the carbon source, the silicon source and the carrier gas into the mixing chamber to perform mixed preheating in the mixing chamber; the feed flow rates of the silicon source feed pipeline and the carbon source feed pipeline are 0.5-5 m / s, and the mass ratio of the silicon source, the carbon source and the carrier gas is 1:(0.4-1):(1-5).

6. A method for preparing silicon carbide crystal, based on the silicon carbide crystal deposition device as claimed in claim 5, characterized in that: include: The carbon source, the silicon source and the carrier gas are respectively introduced into the preheating mixing module for mixing and preheating; The mixed material after mixing and preheating enters the photocatalytic reaction module for photocatalytic reaction and metal activation reaction; The activated mixed material is transported to a deposition chamber for a crystal deposition reaction; wherein the reaction temperature in the deposition chamber is 200°C to 300°C higher than the preheating temperature of the mixture.

7. The method for preparing silicon carbide crystal according to claim 6, characterized in that: The temperature of the deposition chamber is 500° C. to 800° C., and the pressure is 20 to 500 kPa.

8. The method for preparing silicon carbide crystal according to claim 6, characterized in that: The activation light source is ultraviolet light, and the wavelength of the ultraviolet light is 100nm~400nm; the intensity power range of the activation light source is 10~300KWh; the mixed and preheated mixed material enters the photocatalytic reaction module for photocatalytic reaction and metal activation reaction, and the material residence time is 30~600s.

9. The method for preparing silicon carbide crystal according to claim 6, characterized in that: The feed flow rates of the silicon source feed pipeline and the carbon source feed pipeline are 0.5~5m / s, and the mass ratio of the silicon source, carbon source and carrier gas is 1:(0.4~1):(1~5); the feed amount of the silicon source is 1~400kg / h, and the feed amount of the carbon source is 1~400kg / h; the deposition rate of the deposition chamber is 1mm / h~10mm / h.

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