Device and method for preparing tantalum carbide film layer on graphite component surface and graphite component
By using a flow guide on the inner surface of the graphite crucible, the tantalum pentoxide raw material gas reacts with the graphite components to form a tantalum carbide film layer, the problems of high preparation cost and high porosity of the film layer in the prior art are solved, and high quality is achieved. Silicon carbide single crystal growth.
Patent Information
- Application Number
- CN202411132799.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-19
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2044-08-19
AI Technical Summary
Prior art When preparing a tantalum carbide film layer on the inner surface of a graphite crucible, the cost is high and the film layer has a high porosity, resulting in many crystal defects and affecting the quality of the single crystal of silicon carbide.
Using a crucible part with a hollow structure and a graphite component combination device, the tantalum pentoxide raw material gas is guided to react with the inner surface of the graphite component at high temperature through the flow guide to form a dense tantalum carbide film layer.
The preparation cost of the tantalum carbide film layer is significantly reduced, the density of the film layer is improved, the defects of silicon carbide single crystal are reduced, the service life of the graphite crucible is extended, and the crystal quality is improved.
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Figure CN118652135B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of derivatives of silicon carbide crystal growth, and in particular relates to a preparation device and method for a tantalum carbide film layer on the surface of a graphite component, and a graphite component. Background Art
[0002] Physical vapor transport (PVT) is currently the main method for industrially growing silicon carbide crystals. Specifically, silicon carbide polycrystalline raw materials are placed in a closed cavity formed by a graphite crucible and a crucible cover, and a silicon carbide seed crystal is bonded to the inner wall of the crucible cover. The heating body outside the graphite crucible heats the silicon carbide polycrystalline raw materials in the graphite crucible to sublimate and decompose. The sublimated and decomposed gas grows on the silicon carbide seed crystal to obtain a silicon carbide single crystal.
[0003] Si and Si produced by decomposition and sublimation of silicon carbide raw materials x C y Atomic groups will corrode the inner surface of the graphite crucible at high temperatures. On the one hand, corrosion will reduce the life of the graphite crucible. On the other hand, it will produce graphite powder, which will easily float to the crystal growth interface with the air flow to form carbon inclusions. At the same time, the graphite crucible will produce ash at high temperatures. The ash is released from the pores of the graphite crucible and is also easy to float to the crystal growth interface to form inclusions, affecting the crystal quality.
[0004] The inner surface of the graphite crucible is covered with a dense tantalum carbide film layer, which can prevent Si and Si x C y Atomic groups corrode the inner surface of the graphite crucible and prevent graphite ash from escaping into the crystal growth space. Chemical vapor deposition (CVD) can prepare a dense tantalum carbide film on the surface of the graphite crucible, but CVD equipment is expensive, single furnace capacity is low, and the cost of preparing tantalum carbide film is high, about 40% of the crystal price, and cannot be mass-produced.
[0005] After brushing the surface of the graphite crucible with a slurry containing tantalum carbide powder, it is baked at a temperature above 2000°C to prepare a tantalum carbide film. Although the cost of preparing the tantalum carbide film is slightly reduced, the prepared tantalum carbide film is not dense enough and has a high porosity, and cannot effectively block Si and Si x C y The corrosion of graphite parts by atomic groups and the escape of ash from the inside of graphite parts will cause the grown crystals to have more defects and limited crystal quality. Summary of the invention
[0006] The purpose of the present invention is to overcome the defects of the prior art in preparing a tantalum carbide film layer on the inner surface of a graphite crucible, such as high preparation cost, high porosity of the tantalum carbide film layer, and many crystal defects obtained by growth, and to provide a preparation device, method and graphite component for a tantalum carbide film layer on the surface of a graphite component, thereby significantly reducing the preparation cost of the tantalum carbide film layer and improving the density of the tantalum carbide film layer.
[0007] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a device for preparing a tantalum carbide film layer on the surface of a graphite component, comprising:
[0008] The crucible part has a hollow structure, the lower part of which is a tantalum pentoxide receiving part, and the crucible part includes a circumferentially surrounding crucible wall;
[0009] A graphite component, which is coaxially arranged with the crucible portion, is located above the crucible portion, and has a lower end sealed and fixedly connected to an upper end of the crucible wall;
[0010] The guide member includes a cylindrical section, wherein the cylindrical section is located inside the graphite component, the cylindrical section is coaxially arranged with the graphite component, an outer wall of the cylindrical section and an inner surface of the graphite component are spaced apart, the guide member is located above the tantalum pentoxide containing portion, and the space is communicated with the tantalum pentoxide containing portion.
[0011] In some preferred embodiments, the guide member includes an expanded diameter section, which is located at the upper part of the hollow structure of the crucible portion, the upper end of the expanded diameter section is connected to the lower end of the cylindrical section, the diameter of the outer wall at the lower end of the expanded diameter section is smaller than the diameter of the outer wall at the upper end, the diameter of the outer wall at the upper end of the expanded diameter section is the same as the diameter of the outer wall of the cylindrical section; the ratio of the diameter of the outer wall at the lower end of the expanded diameter section to the diameter of the outer wall at the upper end is 0.1~0.95.
[0012] Preferably, the distance between the lower end of the expanded diameter section and the upper end of the tantalum pentoxide containing portion is 10 mm to 50 mm.
[0013] In some preferred embodiments, the bottom center of the inner surface of the crucible portion is a planar structure, the inner surface of the edge of the planar structure extends outward and upward, the lower diameter of the tantalum pentoxide receiving portion is smaller than the upper diameter; the ratio of the diameter of the planar structure to the inner diameter of the crucible wall is 0.1~0.95.
[0014] In some preferred embodiments, the preparation device further comprises a cover body, which covers the upper end of the graphite component, and the lower edge of the cover body vertically extends downward to be sealed and fixedly connected with the upper end of the graphite component.
[0015] Preferably, at least two structures consisting of the crucible parts, the graphite component, the guide member and the cover are stacked, the upper edge of the cover extends vertically upward, and the structure extending vertically upward is sleeved on the bottom periphery of the crucible part above the cover.
[0016] In some preferred embodiments, the diameter d of the outer wall of the cylindrical section and the inner diameter D of the graphite component satisfy 0.5D≤d≤0.99D.
[0017] In a second aspect, the present invention provides a method for preparing a tantalum carbide film layer on the surface of a graphite component using the preparation device described in the first aspect, comprising:
[0018] Add tantalum pentoxide raw material into the tantalum pentoxide containing part, place the preparation device in a high-temperature furnace, and under an inert atmosphere, when the pressure in the high-temperature furnace cavity is 1.0Pa~1000Pa, adjust the temperature of the crucible part to 1900℃~2100℃ for the first insulation treatment.
[0019] In some preferred embodiments, the preparation method further comprises: after the first heat preservation treatment, adjusting the temperature of the crucible part to 2200° C. to 2300° C., and performing a second heat preservation treatment.
[0020] In a third aspect, the present invention provides a graphite component, the inner surface of which has a tantalum carbide film layer prepared by the preparation method described in the second aspect.
[0021] In the present invention, the crucible part has a hollow structure, the lower part of the hollow structure is a tantalum pentoxide receiving part, the graphite component is coaxially arranged with the crucible part and is located above the crucible part, the lower end of the graphite component is sealed and fixedly connected with the upper end of the crucible wall, the columnar section of the guide member is located inside the graphite component, the columnar section is coaxially arranged with the graphite component, the guide member is located above the tantalum pentoxide receiving part, the outer wall of the columnar section and the inner surface of the graphite component leave a gap connected to the tantalum pentoxide receiving part, and tantalum pentoxide raw material is added into the tantalum pentoxide receiving part. The preparation device is placed in a high-temperature furnace, the temperature of the crucible is raised to above 1900°C, the tantalum pentoxide raw material is melted and evaporated at high temperature, and the tantalum pentoxide gas flows to the inner surface of the graphite component through the gap between the outer wall of the columnar section of the guide member and the inner surface of the graphite component, and reacts with the carbon on the inner surface of the graphite component to form tantalum carbide, which can form a dense tantalum carbide film layer on the inner surface of the graphite component. When the graphite component is used for the growth of silicon carbide single crystals, the defects of the grown silicon carbide single crystals can be significantly reduced, and the crystal quality can be improved. Using low-priced tantalum pentoxide as a raw material and being able to prepare a tantalum carbide film layer in a conventional high-temperature furnace can greatly reduce the preparation cost of the tantalum carbide film layer. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.
[0023] Figure 1 It is a structural schematic diagram of a specific implementation method of a device for preparing a tantalum carbide film layer on the surface of a graphite component of the present invention.
[0024] Description of Reference Numerals
[0025] 1. Crucible part; 101. Crucible wall; 102. Plane structure; 2. Graphite component; 3. Flow guide; 301. Column section; 302. Expanded diameter section; 4. Cover body. DETAILED DESCRIPTION
[0026] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0027] In this document, unless otherwise specified, directional words such as "upper" and "lower" are generally understood in combination with the directions shown in the drawings and actual applications, and "inside" and "outside" refer to the inside and outside of the outline of a component.
[0028] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "vertical", "bottom", "inside", "outside", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying 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.
[0029] In the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", "fixed" and the like 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 a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
[0031] The inventors of the present invention have found that the prior art uses a CVD method to prepare a tantalum carbide film layer on the surface of a graphite component, which has a high preparation cost. Although the preparation cost is slightly reduced by using tantalum carbide micropowder to prepare a tantalum carbide film layer, the prepared tantalum carbide film layer is not dense enough, has a high porosity, and the grown crystals have many defects, which has a limited effect on improving the crystal quality.
[0032] In this first aspect, the present invention provides a device for preparing a tantalum carbide film layer on the surface of a graphite component, referring to Figure 1 , comprising: a crucible portion 1, which has a hollow structure, the lower part of which is a tantalum pentoxide receiving portion, which includes a circumferentially surrounding crucible wall 101;
[0033] A graphite component 2, which is coaxially arranged with the crucible portion 1, is located above the crucible portion 1, and has a lower end sealed and fixedly connected to an upper end of the crucible wall 101;
[0034] The guide member 3 includes a cylindrical section 301, which is located inside the graphite component 2. The cylindrical section 301 is coaxially arranged with the graphite component 2. The outer wall of the cylindrical section 301 is spaced from the inner surface of the graphite component 2. The guide member 3 is located above the tantalum pentoxide containing portion, and the space is connected to the tantalum pentoxide containing portion.
[0035] The preparation device of the present invention has a crucible part with a hollow structure, the lower part of the hollow structure is a tantalum pentoxide receiving part, the graphite component is coaxially arranged with the crucible part and is located above the crucible part, the lower end of the graphite component is sealed and fixedly connected with the upper end of the crucible wall, the tantalum pentoxide raw material is added into the tantalum pentoxide receiving part, the preparation device is placed in a high-temperature furnace, the temperature of the crucible part is raised to above 1900°C, the tantalum pentoxide raw material in the tantalum pentoxide receiving part is melted and evaporated at high temperature, the tantalum pentoxide gas flows to the inner surface of the graphite component, and reacts with the carbon on the inner surface of the graphite component to generate tantalum carbide, which can form a dense tantalum carbide film layer on the inner surface of the graphite component, and when the graphite component is used to grow silicon carbide single crystals, it can significantly inhibit Si and Si x C yThe atomic groups corrode the inner surface of the graphite crucible at high temperature, which increases the life of the graphite crucible, inhibits the generation of graphite powder, inhibits the graphite powder and the ash inside the graphite parts from floating to the crystal growth interface with the airflow, reduces the defects of the grown silicon carbide single crystal, and improves the crystal quality. Using low-priced tantalum pentoxide as a raw material and preparing tantalum carbide film in a conventional high-temperature furnace can greatly reduce the preparation cost of tantalum carbide film.
[0036] In the present invention, a flow guide is arranged above the tantalum pentoxide accommodation portion, the cylindrical section of the flow guide is arranged inside the graphite component, the cylindrical section and the graphite component are arranged coaxially, the outer wall of the cylindrical section and the inner surface of the graphite component are spaced apart, the space is connected to the tantalum pentoxide accommodation portion, the flow guide guides the tantalum pentoxide gas obtained by evaporating the tantalum pentoxide raw material to flow through the space between the outer wall of the cylindrical section of the flow guide and the inner surface of the graphite component, compared with not arranging the flow guide, the tantalum pentoxide gas can flow quickly to the inner surface of the graphite component, react with the carbon on the inner surface of the graphite component, and improve the preparation efficiency of the tantalum carbide film layer, the cylindrical section of the flow guide is arranged inside the graphite component, the cylindrical section and the graphite component are arranged coaxially, the outer wall of the cylindrical section and the inner surface of the graphite component are spaced apart The cylindrical section of the guide piece squeezes more tantalum pentoxide gas toward the inner surface of the graphite component, which can increase the concentration of tantalum pentoxide gas near the inner surface of the graphite component. On the one hand, the reaction rate of tantalum pentoxide gas and carbon on the surface of the graphite component is increased, and the preparation efficiency of tantalum carbide film layer is improved. On the other hand, the pressure near the inner surface of the graphite component is increased, the density of the tantalum carbide film layer is increased, and the bonding force between the tantalum carbide film layer and the inner surface of the graphite component is increased to prevent the tantalum carbide film layer from falling off. The tantalum pentoxide gas flows through the gap between the outer wall of the cylindrical section of the guide piece and the inner surface of the graphite component and flows toward the inner surface of the graphite component, which can make the tantalum pentoxide gas react evenly with the carbon on the inner surface of the graphite component, and evenly form a dense tantalum carbide film layer on the inner surface of the graphite component.
[0037] The graphite component of the present invention may be in the form of a cylindrical barrel, and specifically may be, for example, a graphite crucible wall of a device for growing silicon carbide crystals using a physical vapor transport method.
[0038] The present invention does not limit the internal structure of the columnar section of the flow guide, and the columnar section may be a solid structure or a hollow structure. It can be understood that the flow guide of the present invention is fixedly connected to the crucible portion to support the flow guide, for example, it can be fixedly connected by a support, preferably, the columnar section is a hollow structure, specifically, for example, it can be in the form of a cylindrical barrel.
[0039] It can be understood that the material of the flow guide of the present invention has high stability at high temperatures and does not react with tantalum pentoxide gas.
[0040] In some preferred embodiments, the vertical distance between the upper end of the columnar segment 301 and the upper end of the graphite component 2 is 0 mm to 50 mm, which is more conducive to allowing more tantalum pentoxide gas to react with carbon on the inner surface of the graphite component, thereby improving the preparation efficiency of the tantalum carbide film layer.
[0041] In some preferred embodiments, the guide member 3 includes an expanded diameter section 302, which is located at the upper part of the hollow structure of the crucible portion 1, and the upper end of the expanded diameter section 302 is connected to the lower end of the cylindrical section 301, the diameter of the outer wall at the lower end of the expanded diameter section 302 is smaller than the diameter of the outer wall at the upper end, and the diameter of the outer wall at the upper end of the expanded diameter section 302 is the same as the diameter of the outer wall of the cylindrical section 301; the ratio of the diameter of the outer wall at the lower end of the expanded diameter section 302 to the diameter of the outer wall at the upper end is 0.1~0.95. In this preferred embodiment, the guide member includes an expanded diameter section, the upper end of the expanded diameter section is connected to the lower end of the cylindrical section, the diameter of the outer wall of the upper end of the expanded diameter section is the same as the diameter of the cylindrical section, the expanded diameter section is located at the upper part of the hollow structure of the crucible part, and the guide member includes an expanded diameter section extending into the hollow structure of the crucible part, the diameter of the outer wall of the lower end of the expanded diameter section is smaller than the diameter of the outer wall of the upper end. In the process of preparing the tantalum carbide film layer, on the one hand, the inclined surface structure of the expanded diameter section of the guide member can guide the evaporated tantalum pentoxide gas to flow quickly to the inner surface of the graphite component 2, and on the other hand, the bottom center position of the guide member The distance to the raw material surface of tantalum pentoxide is closer, and the concentration of tantalum pentoxide raw material gas at the lower center of the guide is higher, which increases the concentration gradient of tantalum pentoxide raw material gas from the lower center of the guide to the lower edge of the guide to the outer wall of the columnar section and the inner surface of the graphite component, so that the tantalum pentoxide raw material gas at the lower center of the guide pushes the tantalum pentoxide raw material gas at the lower edge of the guide to flow quickly to the inner surface of the graphite component 2, and all the tantalum pentoxide raw material gas flows quickly to the inner surface of the graphite component. The tantalum pentoxide raw material gas flows quickly to the inner surface of the graphite component, which is more conducive to quickly increasing the pressure near the inner surface of the graphite component, improving the compactness of the tantalum carbide film layer, improving the bonding force between the tantalum carbide film layer and the inner surface of the graphite component, and preventing the tantalum carbide film layer from falling off. The ratio of the diameter of the outer wall at the lower end of the expanded diameter section 302 to the diameter of the outer wall at the upper end is 0.1-0.95, which is more conducive to the tantalum pentoxide raw material gas at the lower center part of the guide member to push the tantalum pentoxide raw material gas at the lower edge part of the guide member to flow quickly to the inner surface of the graphite component together, and all the raw material gas generated by the melting and evaporation of the tantalum pentoxide raw material flows quickly to the inner surface of the graphite component. Preferably, the ratio of the diameter of the outer wall at the lower end of the expanded diameter section 302 to the diameter of the outer wall at the upper end is 0.2-0.5.
[0042] The present invention does not limit the internal structure of the diameter-expanding section connected to the lower end of the cylindrical section, and the diameter-expanding section may be a solid structure or a hollow structure. Preferably, the diameter-expanding section is a hollow structure.
[0043] Preferably, the distance between the lower end of the expanded diameter section 302 and the upper end of the tantalum pentoxide receiving portion is 10 mm to 50 mm. The distance between the lower end of the expanded diameter section 302 and the upper end of the tantalum pentoxide receiving portion is not greater than 50 mm, which is more conducive to increasing the concentration of the tantalum pentoxide raw material gas at the lower center of the guide member, increasing the concentration gradient of the tantalum pentoxide raw material gas from the lower center of the guide member to the lower edge of the guide member to the outer wall of the cylindrical section and the inner surface of the graphite component, so that most of the tantalum pentoxide raw material gas quickly flows to the inner surface of the graphite component, quickly increases the pressure near the inner surface of the graphite component, and improves the bonding force between the tantalum carbide film layer and the graphite component.
[0044] In some preferred embodiments, the bottom center of the inner surface of the crucible portion 1 is a planar structure 102, the inner surface of the edge of the planar structure 102 extends outward and upward, and the lower diameter of the tantalum pentoxide receiving portion is smaller than the upper diameter; the ratio of the diameter of the planar structure 102 to the inner diameter of the crucible wall 101 is 0.1~0.95. Under this preferred embodiment, the center of the bottom of the inner surface of the crucible part is a plane structure, and the inner surface of the edge of the plane structure extends outward and upward, and the lower diameter of the tantalum pentoxide accommodating part is smaller than the upper diameter. On the one hand, the structure of the bottom of the inner surface of the crucible part extending outward and upward can guide the evaporated tantalum pentoxide gas to flow quickly to the inner surface of the graphite component 2. On the other hand, the lower middle position of the hollow structure of the crucible part can accommodate more tantalum pentoxide raw materials, which can increase the concentration of the tantalum pentoxide raw material gas in the lower center position of the guide member, and increase the concentration gradient of the tantalum pentoxide raw material gas from the lower center of the guide member to the lower edge of the guide member to the outer wall of the cylindrical section and the inner surface of the graphite component, so that the tantalum pentoxide raw material gas in the lower center part of the guide member pushes the tantalum pentoxide raw material gas in the lower edge part of the guide member, and they flow quickly to the inner surface of the graphite component together. By allowing the tantalum pentoxide raw material gas to flow quickly to the inner surface of the graphite component, it is more conducive to quickly increasing the pressure near the inner surface of the graphite component, increasing the density of the tantalum carbide film layer, and increasing the bonding force between the tantalum carbide film layer and the inner surface of the graphite component. The ratio of the diameter of the planar structure 102 to the inner diameter of the crucible wall 101 is 0.1-0.95, which is more conducive to the tantalum pentoxide raw material gas in the lower center part of the guide member pushing the tantalum pentoxide raw material gas in the lower edge part of the guide member to flow quickly to the inner surface of the graphite component together, and all the raw material gas generated by the melting and evaporation of the tantalum pentoxide raw material flows quickly to the inner surface of the graphite component. Preferably, the ratio of the diameter of the planar structure 102 to the inner diameter of the crucible wall 101 is 0.2-0.5.
[0045] In some preferred embodiments, the preparation device further comprises a cover 4, which covers the upper end of the graphite component 2, and the lower edge of which extends vertically downward to be sealed and fixedly connected with the upper end of the graphite component 2. Under this preferred embodiment, the lower edge of the cover extends vertically downward to be sealed and fixedly connected with the upper end of the graphite component, which is more conducive to preventing tantalum pentoxide gas from escaping from the preparation device and improving the preparation efficiency of the tantalum pentoxide film layer on the inner surface of the graphite component. When the vertical distance between the upper end of the columnar segment 301 and the upper end of the graphite component 2 is 0 mm, the upper end of the columnar segment 301 can form a surface contact with the lower surface of the cover, and the upper end of the columnar segment 301 can be connected with the lower surface of the cover.
[0046] Preferably, at least two structures consisting of the crucible part 1, the graphite component 2, the flow guide 3 and the cover 4 are stacked, the upper edge of the cover 4 extends vertically upward, and the structure extending vertically upward is sleeved on the bottom periphery of the crucible part 1 above the cover 4. In this preferred embodiment, the lower edge of the cover extends vertically downward to be sealed and fixedly connected with the upper end of the graphite component 2, the upper edge of the cover 4 extends vertically upward, and the structure extending vertically upward is sleeved on the bottom periphery of the crucible part 1 above the cover 4, and the cover 4 forms an "I"-shaped structure. The cover can simultaneously seal the structure consisting of the lower crucible part 1, the graphite component 2 and the flow guide 3, and position the structure consisting of the upper crucible part 1, the graphite component 2 and the flow guide 3, which is more conducive to preparing tantalum carbide film layers on the surfaces of multiple graphite components at the same time, thereby reducing the preparation cost of tantalum carbide film layers.
[0047] In some preferred embodiments, the diameter d of the outer wall of the cylindrical section 301 and the inner diameter D of the graphite component 2 satisfy 0.5D≤d≤0.99D. Under this preferred embodiment, the diameter d of the outer wall of the cylindrical section is not less than 0.5 times the inner diameter D of the graphite component. The spacing between the outer wall of the cylindrical section and the inner surface of the graphite component is adjusted to squeeze more tantalum pentoxide gas toward the inner surface of the graphite component. The concentration of tantalum pentoxide gas near the inner surface of the graphite component is higher, and the pressure near the inner surface of the graphite component is higher. The pressure near the inner surface of the graphite component will be greater than the pressure outside the graphite component in a short time. On the one hand, it is more conducive to improving the density of the tantalum carbide film layer. On the other hand, the porosity of the graphite component is usually greater than 15%. Part of the tantalum pentoxide gas can easily penetrate from the inner surface of the graphite component into the pores of the graphite component, react with the graphite in the pores of the graphite component to generate tantalum carbide, and the tantalum carbide film layer extends into the inner layer pores of the graphite component, which is more conducive to improving the bonding force between the tantalum carbide film layer and the inner surface of the graphite component, and preventing the tantalum carbide film layer from falling off.
[0048] It can be understood that the tantalum pentoxide gas of the present invention reaches the inner surface of the graphite component, a part of it reacts with the graphite on the inner surface of the graphite component to generate tantalum carbide, a part of the tantalum pentoxide gas condenses on the inner surface of the graphite component, and reacts in the reducing atmosphere of carbon monoxide to generate tantalum carbide, and a part of the tantalum pentoxide gas penetrates into the pores of the graphite component and reacts with the graphite in the pores of the graphite component to generate tantalum carbide.
[0049] In a second aspect, the present invention provides a method for preparing a tantalum carbide film layer on the surface of a graphite component using the preparation device described in the first aspect, comprising: adding a tantalum pentoxide raw material into a tantalum pentoxide containing portion, placing the preparation device in a high-temperature furnace, and in an inert atmosphere, when the pressure in the high-temperature furnace cavity is 1.0Pa~1000Pa, adjusting the temperature of the crucible portion 1 to 1900℃~2100℃, and performing a first insulation treatment.
[0050] The preparation method of the present invention comprises the following steps: adjusting the temperature of the crucible portion to 1880°C, causing solid tantalum pentoxide to begin to melt into liquid; adjusting the temperature of the crucible portion to 1900°C to 2100°C under a pressure of 1.0 Pa to 1000 Pa, causing the tantalum pentoxide liquid to rapidly volatilize into gas; the inner space of the graphite component is occupied by the columnar section of the flow guide; a large amount of tantalum pentoxide gas is distributed in the gap between the outer wall of the columnar section and the inner surface of the graphite component; the pressure in the gap between the outer wall of the columnar section and the inner surface of the graphite component will be significantly higher than the pressure outside the graphite component in a short time; the porosity of the graphite component is generally greater than 15%; part of the tantalum pentoxide gas easily penetrates from the inner surface of the graphite component into the pores of the graphite component, reacts with graphite in the pores of the graphite component to generate tantalum carbide; the tantalum carbide film layer extends into the inner layer pores of the graphite component, and is more conducive to improving the bonding force between the tantalum carbide film layer and the graphite component.
[0051] The present invention does not limit the form of the tantalum pentoxide raw material, and specifically, for example, the tantalum pentoxide can be powder, particles or blocks.
[0052] In some preferred embodiments, the preparation method further comprises: after the first heat preservation treatment, adjusting the temperature of the crucible part 1 to 2200°C to 2300°C, and performing a second heat preservation treatment. Under this preferred scheme, after the first heat preservation treatment, the temperature of the crucible part 1 is increased, and a second heat preservation treatment is performed, preferably, adjusted to 2200°C to 2300°C, and the generated tantalum carbide film layer is calcined, which is more conducive to improving the density of the tantalum carbide film layer, increasing the bonding force between the tantalum carbide film layer and the inner surface of the graphite component, and preventing the tantalum carbide film layer from falling off.
[0053] Preferably, after the second insulation treatment, an inert gas is filled into the high-temperature furnace cavity to make the pressure in the cavity 10000Pa~20000Pa, and then the crucible is cooled at a cooling rate of 1°C / min~4°C / min until the power of the high-temperature furnace heater drops to 0.
[0054] In some preferred embodiments, after the preparation device is placed in the high-temperature furnace, before the temperature of the crucible portion is adjusted to 1900°C to 2100°C, the preparation method further comprises: starting a mechanical pump to evacuate the high-temperature furnace cavity to a pressure of 0.1Pa-10Pa, starting a molecular pump to evacuate the high-temperature furnace cavity to a pressure of 10 -4 Pa-10 -3 Pa, increase the power of the high-temperature furnace heater, and make the temperature of the crucible reach 700℃~900℃ at a heating rate of 3℃ / min~6℃ / min, and fill the high-temperature furnace cavity with inert gas at a speed of 10L / h~200L / h. When the pressure in the high-temperature furnace cavity reaches 1000Pa~2000Pa, the temperature of the crucible reaches 1300℃~1500℃ at a heating rate of 3℃ / min~6℃ / min, adjust the power of the heater, and carry out the third insulation treatment with a insulation time of 2h~5h. Continue to increase the temperature of the crucible to 1600℃~1800℃ at a heating rate of 2℃ / min~4℃ / min, and adjust the pressure in the high-temperature furnace cavity to 1.0Pa~1000Pa.
[0055] In a third aspect, the present invention provides a graphite component, the inner surface of which has a tantalum carbide film layer prepared by the preparation method described in the second aspect. When the graphite component of the present invention is used to grow a silicon carbide single crystal, it can significantly inhibit the Si and Si x C y The atomic groups corrode the inner surface of the graphite crucible at high temperature, thereby increasing the life of the graphite crucible, reducing defects in the grown silicon carbide single crystal, and improving the crystal quality.
[0056] The present invention is further described in detail below with reference to specific embodiments.
[0057] Example 1
[0058] A device for preparing a tantalum carbide film layer on the surface of a graphite component, the preparation device comprising a crucible part 1, a graphite component 2, a flow guide 3 and a cover body 4, the crucible part 1 having a circumferentially surrounding crucible wall 101, the circumferentially surrounding crucible wall 101 and the crucible bottom forming a hollow structure, the lower part of the hollow structure being a tantalum pentoxide accommodating part, the bottom center of the inner surface of the crucible part 1 being a plane structure 102, the inner surface of the edge of the plane structure extending outwardly and upwardly inclined, the lower diameter of the tantalum pentoxide accommodating part being smaller than the upper diameter, the ratio of the diameter of the plane structure 102 to the inner diameter of the crucible wall 101 being 0.4; the graphite component 2 being a graphite crucible wall of a device for growing silicon carbide crystals, the graphite component 2 in the form of a cylindrical barrel being located above the crucible part 1, being coaxially arranged with the crucible part 1, and the lower end being fixedly connected to the upper end of the crucible wall by threaded sealing;
[0059] The guide member 3 includes a cylindrical section 301 and an expanded diameter section 302. The upper end of the expanded diameter section 302 is connected to the lower end of the cylindrical section 301. The diameter of the outer wall of the upper end of the expanded diameter section 302 is the same as the diameter of the outer wall of the cylindrical section 301. The diameter of the outer wall of the lower end of the expanded diameter section 302 is smaller than the diameter of the outer wall of the upper end. The ratio of the diameter of the outer wall of the lower end of the expanded diameter section 302 to the diameter of the outer wall of the upper end is 0.25. The guide member 3 is located above the tantalum pentoxide accommodation portion. The cylindrical section 301 is located inside the graphite component 2. The cylindrical section 301 is coaxially arranged with the graphite component 2. The vertical distance between the upper end and the upper end of the graphite component 2 is 0 mm, there is a gap between the outer wall of the cylindrical section 301 and the inner surface of the graphite component 2, the ratio of the diameter d of the outer wall of the cylindrical section 301 to the inner diameter D of the graphite component 2 is 0.8, the gap is connected to the tantalum pentoxide accommodation portion, the expanded diameter section 302 is located at the upper part of the hollow structure of the crucible portion 1, and is fixedly connected to the crucible portion 1, and the distance between the lower end of the expanded diameter section 302 and the upper end of the tantalum pentoxide accommodation portion is 25 mm; the lower edge of the cover body 4 extends vertically downward, and the upper edge of the cover body 4 extends vertically upward.
[0060] A method for preparing a tantalum carbide film layer on the surface of a graphite component, comprising:
[0061] Step 1: Add tantalum pentoxide particles into the tantalum pentoxide receiving portion at the bottom of the hollow structure of the crucible part 1, cover the upper end of the graphite component 2 with the cover body 4, and fix the structure of the lower edge of the cover body 4 extending vertically downward to the upper end of the graphite component 2 to seal and fix the cover body 4 and the graphite component 2 together, stack a plurality of preparation devices consisting of the crucible part 1, the graphite component 2, the guide member 3 and the cover body 4, and the structure of the upper edge of the cover body 4 extending vertically upward is sleeved on the bottom periphery of the crucible part above the cover body 4, and place the stacked preparation devices in a high-temperature furnace;
[0062] Step 2: Turn on the mechanical pump and evacuate the high-temperature furnace chamber to a pressure of 0.1Pa-10Pa. Turn on the molecular pump and evacuate the high-temperature furnace chamber to a pressure of 10-4 Pa-10 -3 Pa, increase the power of the high-temperature furnace heater, make the temperature of the crucible reach 800°C at a heating rate of 4°C / min, fill the high-temperature furnace cavity with inert gas at a rate of 10L / h~200L / h, when the pressure in the high-temperature furnace cavity reaches 1500Pa, make the temperature of the crucible reach 1400°C at a heating rate of 4°C / min, adjust the power of the heater, carry out the third insulation treatment, the insulation time is 4h, continue to make the temperature of the crucible reach 1700°C at a heating rate of 3°C / min, and adjust the pressure in the high-temperature furnace cavity to 300Pa;
[0063] Step 3: The temperature of the crucible part reaches 2000°C at a heating rate of 3°C / min, and a first insulation treatment is performed for 5 hours. After the first insulation treatment, the temperature of the crucible part 1 is adjusted to 2200°C, and a second insulation treatment is performed for 3 hours;
[0064] Step 4: Fill the high-temperature furnace cavity with inert gas to make the pressure in the cavity reach 15000Pa, then cool the crucible at a cooling rate of 1℃ / min~3℃ / min until the power of the high-temperature furnace heater drops to 0.
[0065] Example 2
[0066] Refer to Example 1, the difference is that in step three, the second insulation treatment is not performed, and step four is performed after the first insulation treatment.
[0067] Example 3
[0068] The method is carried out in accordance with Example 1, except that in the preparation device, the ratio of the diameter d of the outer wall of the cylindrical section 301 to the inner diameter D of the graphite component 2 is 0.4.
[0069] Example 4
[0070] The method is carried out with reference to Example 1, except that in the preparation device, the bottom of the inner surface of the crucible portion 1 is flat, and there is no structure in which the center of the bottom of the inner surface of the crucible portion 1 is a flat structure 102, and the inner surface of the edge of the flat structure extends outward and upward.
[0071] Comparative Example 1
[0072] The process is carried out with reference to Example 1, except that no flow guide 3 is provided in the preparation device.
[0073] Comparative Example 2
[0074] The method is carried out in accordance with Example 1, except that tantalum pentoxide particles are not placed in the lower part of the hollow structure of the crucible part 1. After a slurry containing tantalum carbide powder is brushed on the surface of the graphite part 2, the preparation device is placed in a high-temperature furnace, the temperature of the high-temperature furnace is set to 2000°C, and the temperature is maintained for 5 hours for baking treatment.
[0075] The bonding force between the tantalum carbide film layer obtained in the above embodiments and comparative examples and the inner surface of the graphite component and the density of the tantalum carbide film layer were detected, and the results are shown in Table 1. The bonding force detection method is the hundred grid method, which is divided into 6 levels according to the size of the bonding force, where the bonding force is the best when the level is 0 and the worst when the level is 5. The density of the film layer is characterized by the number of furnaces used for the graphite crucible, and the more furnaces used, the higher the density.
[0076] Table 1
[0077]
[0078] Comparative Examples 1 to 4, during the preparation of the tantalum carbide film layer, after the first insulation treatment, the temperature of the crucible part is adjusted to 2200°C~2300°C, and the second insulation treatment is performed. The diameter d of the outer wall of the cylindrical section 301 and the inner diameter D of the graphite component 2 satisfy 0.5D≤d≤0.99D, and the bottom center of the inner surface of the crucible part 1 is a plane structure 102, and the inner surface of the edge of the plane structure 102 extends outward and upward, which is more conducive to improving the density of the tantalum carbide film layer, increasing the average number of furnaces used for the graphite crucible, and improving the bonding force between the tantalum carbide film layer and the inner surface of the graphite component to prevent the tantalum carbide film layer from falling off.
[0079] Comparing the embodiments and comparative examples, compared with brushing a slurry containing tantalum carbide powder on the surface of the graphite component 2 and then baking it, and compared with not providing a guide piece, the scheme of the present invention can improve the density of the tantalum carbide film layer, increase the average use of the graphite crucible, increase the bonding force between the tantalum carbide film layer and the inner surface of the graphite component, and prevent the tantalum carbide film layer from falling off.
[0080] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A device for preparing a tantalum carbide film layer on the surface of a graphite component, characterized in that: include: A crucible part (1) having a hollow structure, wherein the lower part of the hollow structure is a tantalum pentoxide receiving part, which comprises a circumferentially surrounding crucible wall (101); a graphite component (2) which is coaxially arranged with the crucible portion (1), is located above the crucible portion (1), and has a lower end which is sealed and fixedly connected to the upper end of the crucible wall (101); A flow guide (3), comprising a columnar section (301), the columnar section (301) being located inside the graphite component (2), the columnar section (301) being coaxially arranged with the graphite component (2), the outer wall of the columnar section (301) being spaced from the inner surface of the graphite component (2), the columnar section (301) being located above the tantalum pentoxide containing portion, the space being in communication with the tantalum pentoxide containing portion; The flow guide (3) comprises an expanded diameter section (302), the expanded diameter section (302) being located at the upper part of the hollow structure of the crucible portion (1), the upper end of the expanded diameter section (302) being connected to the lower end of the columnar section (301), the diameter of the outer wall of the lower end of the expanded diameter section (302) being smaller than the diameter of the outer wall of the upper end, the diameter of the outer wall of the upper end of the expanded diameter section (302) being the same as the diameter of the outer wall of the columnar section (301); the ratio of the diameter of the outer wall of the lower end of the expanded diameter section (302) to the diameter of the outer wall of the upper end is 0.1-0.95; The distance between the lower end of the expanded diameter section (302) and the upper end of the tantalum pentoxide containing portion is 10 mm to 50 mm; The center of the bottom of the inner surface of the crucible portion (1) is a plane structure (102), the inner surface of the edge of the plane structure (102) extends outwardly and upwardly, the lower diameter of the tantalum pentoxide receiving portion is smaller than the upper diameter; the ratio of the diameter of the plane structure (102) to the inner diameter of the crucible wall (101) is 0.1-0.95; The diameter d of the outer wall of the cylindrical section (301) and the inner diameter D of the graphite component (2) satisfy 0.5D≤d≤0.99D.
2. The preparation device according to claim 1, characterized in that: The preparation device further comprises a cover body (4), which covers the upper end of the graphite component (2), and the lower edge of which extends vertically downward to be sealed and fixedly connected to the upper end of the graphite component (2).
3. The preparation device according to claim 2, characterized in that: A structure consisting of at least two stacked crucible parts (1), a graphite component (2), a flow guide (3) and a cover body (4), wherein the upper edge of the cover body (4) extends vertically upwards, and the structure extending vertically upwards is sleeved on the outer periphery of the bottom of the crucible part (1) above the cover body (4).
4. A method for preparing a tantalum carbide film layer on the surface of a graphite component using the preparation device according to any one of claims 1 to 3, characterized in that: include: The tantalum pentoxide raw material is added into the tantalum pentoxide containing part, the preparation device is placed in a high-temperature furnace, and under an inert atmosphere, when the pressure in the high-temperature furnace cavity is 1.0Pa-1000Pa, the temperature of the crucible part (1) is adjusted to 1900°C-2100°C, and a first heat preservation treatment is performed.
5. The preparation method according to claim 4, characterized in that: The preparation method further comprises: after the first heat preservation treatment, adjusting the temperature of the crucible part (1) to 2200° C. to 2300° C., and performing a second heat preservation treatment.