Graphite crucible and crystal growth equipment

Abstract

The utility model discloses a graphite crucible and crystal growth equipment, and the graphite crucible comprises a crucible body which is internally provided with a containing space filled with raw materials to be processed; the flow guide cylinder is arranged in the containing space and is in an inverted circular truncated cone shape, a flow guide side wall used for guiding the upflow from inside to outside in an inclined upward mode is formed on the flow guide cylinder, and the upflow is generated after the raw materials to be processed are heated. The graphite crucible is simple in structure, easy to produce and manufacture and favorable for improving the generation quality of crystals.

Description

Technical Field

[0001] This application belongs to the field of crystal growth equipment technology, specifically relating to a graphite crucible and crystal growth equipment. Background Technology

[0002] Silicon carbide (SiC), as a third-generation wide-bandgap semiconductor material, possesses excellent electrical and thermal properties. Its wide bandgap (2.36–3.26 eV), high dielectric constant (3.26 eV), high thermal conductivity (2–5 W / cm·K), and high saturated electron velocity (2–2.5 × 10⁷ m / s) make it an ideal material for fabricating high-temperature, high-frequency, high-power, and high-voltage electronic devices. Power devices fabricated using silicon carbide single-crystal substrates are widely used in new energy vehicles, high-voltage power transmission, LED lighting, 5G, and aerospace.

[0003] Currently, the mass production of silicon carbide ingots mainly employs the PVT (Physical Vapor Transport) method. When using the PVT method for crystal growth, whether resistance heating or induction heating is used, a graphite crucible is required to hold the raw materials. During silicon carbide crystal growth, heat is transferred from the crucible wall to the raw materials through thermal conduction and a small amount of thermal radiation, heating and decomposing the raw materials into a gaseous state. This gaseous state is then transported through the narrow gaps between the materials to the seed crystal at the top, where it transforms into a solid phase.

[0004] During crystal growth, the temperature distribution within the crucible is generally higher near the outer wall and lower at the center; higher at the bottom and lower at the top. This causes the raw material in the lower middle section to preferentially volatilize, then solidify in the upper middle section of the porous material, hindering sublimation in the solidified area and making crystal growth difficult. The resulting crystals often exhibit a "W" shape with a central depression due to insufficient raw material supply, severely impacting crystal quality. Utility Model Content

[0005] The purpose of this application is to provide a graphite crucible and crystal growth apparatus, wherein the graphite crucible has a simple structure, is easy to manufacture, and is beneficial to improving the quality of crystal formation.

[0006] To achieve the above objectives, the first aspect of this application provides a graphite crucible comprising:

[0007] The crucible body has an internal space for filling the raw materials to be processed.

[0008] A flow guide tube is set in the accommodating space and is shaped like an inverted frustum. The flow guide tube has a flow guide sidewall formed on it to guide the rising airflow from the inside out and at an upward angle. The rising airflow is generated by heating the raw material to be processed.

[0009] In the embodiments of the present application, the peripheral wall of the draft tube is provided with a plurality of air holes distributed in the circumferential direction.

[0010] In the embodiments of the present application, the peripheral wall of the draft tube is provided with a plurality of air hole groups distributed in the direction of the generatrix of the draft tube, and each air hole group includes a plurality of air holes distributed in the circumferential direction.

[0011] In the embodiments of the present application, the bottom wall of the crucible body is provided with a positioning protrusion protruding upward, and the bottom wall of the draft tube is provided with a positioning hole for inserting the positioning protrusion.

[0012] In the embodiments of the present application, the top of the crucible body is provided with a feeding opening, and the vertical distance between the top surface of the draft tube and the feeding opening ranges from 30 cm to 50 cm.

[0013] In the embodiments of the present application, the number of the draft tubes is multiple, and the multiple draft tubes include a first draft tube and a second draft tube, the first draft tube is arranged at the center position inside the crucible body, and the second draft tube is arranged at the periphery of the first draft tube.

[0014] In the embodiments of the present application, the thickness of the wall of the draft tube ranges from 3 mm to 5 mm.

[0015] In the embodiments of the present application, the angle between the side wall of the draft tube and the horizontal plane ranges from 20° to 60°.

[0016] In the embodiments of the present application, the inner side wall of the crucible body is provided with a scale for measuring the stacking height of the raw material to be processed.

[0017] The second aspect of the present application provides a crystal growing device, which comprises the graphite crucible described above.

[0018] According to the above technical solution, the graphite crucible comprises a crucible body and a draft tube, the inside of the crucible body is formed with an accommodation space for filling the raw material to be processed; the draft tube is arranged in the accommodation space and has a reverse circular table shape, and the draft tube is provided with a draft side wall for guiding the upwardly rising gas flow from the inside to the outside and obliquely upwardly, wherein the upwardly rising gas flow is generated after the raw material to be processed is heated. The graphite crucible has a simple structure, the draft side wall guides the upwardly rising gas flow from the inside to the outside and obliquely upwardly, so that the upwardly rising gas flow at the radial inner side and the lower part of the accommodation space flows more smoothly to the top of the accommodation space, the silicon carbide crystal growth interface is improved, the generation quality of the silicon carbide crystal is improved, and the situation that the raw material to be processed is hardened is alleviated.

[0019] Other features and advantages of the embodiments of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of embodiments of the application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application, and together with the description serve to explain embodiments of the application, but are not intended to limit the application. Those of ordinary skill in the art, and the skilled person in the art without creative work, can also obtain other drawings from the structures shown in the drawings. In the drawings:

[0021] Figure 1 is a cross-sectional view of a graphite crucible in an embodiment of the application;

[0022] Figure 2 is a first perspective view of a graphite crucible in an embodiment of the application;

[0023] Figure 3 is a second perspective view of a graphite crucible in an embodiment of the application;

[0024] Figure 4 is a first perspective view of a flow guide cylinder in an embodiment of the application;

[0025] Figure 5 is a cross-sectional view of a flow guide cylinder in an embodiment of the application;

[0026] Figure 6 is a second perspective view of a flow guide cylinder in an embodiment of the application.

[0027] Explanation of reference signs

[0028] 1 - crucible body; 101 - containing space; 102 - positioning protrusion; 103 - feeding opening; 2 - flow guide cylinder; 201 - flow guide side wall; 202 - vent hole; 203 - positioning hole; 204 - containing cavity. DETAILED DESCRIPTION

[0029] The specific embodiments of the application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are intended to illustrate and explain the application, and are not intended to limit the application.

[0030] In an embodiment of the application, a graphite crucible is provided, as shown in Figures 1-3 The graphite crucible comprises:

[0031] a crucible body 1, the interior of the crucible body 1 being formed with a containing space 101 for filling raw materials to be processed;

[0032] a flow guide cylinder 2 arranged in the containing space 101 and in an inverted circular table shape, the flow guide cylinder 2 being formed with a flow guide side wall 201 for guiding the upwardly rising gas flow from inside to outside and obliquely upwardly, wherein the upwardly rising gas flow is generated after the raw materials to be processed are heated.

[0033] Specifically, the graphite crucible in the embodiment is used for producing silicon carbide crystals, and the raw material to be processed is silicon carbide particles. The crucible body 1 is made of isostatic graphite and is in a cylindrical shape, and the top of the containing space 101 is provided with a feeding opening 103 through which the raw material to be processed can enter the containing space 101; the flow guide cylinder 2 is made of isostatic graphite and is in an inverted circular table shape with a wide top and a narrow bottom, and the flow guide side wall 201 is the peripheral wall of the flow guide cylinder 2, and the inside of the flow guide cylinder 2 forms a containing cavity 204 (the vertical section of the containing cavity 204 is in an inverted circular table shape), and the top of the containing cavity 204 is provided with a feeding opening through which the raw material to be processed can enter the containing cavity 204. When producing silicon carbide crystals, the operator first fills the raw material to be processed into the containing space 101 through the feeding opening 103, and after the raw material to be processed is filled, the inside and outside of the flow guide side wall 201 are filled with the raw material to be processed, and then a seed crystal is placed above the raw material to be processed; after the seed crystal is placed, the crucible body 1 is heated, and the crucible body 1 transmits heat to the raw material to be heated in the containing space 101, and after the raw material to be heated is heated, it sublimates and generates an upward gas flow (i.e. gas phase silicon carbide), and the upward gas flow generated by the raw material to be processed at the lower part of the containing space 101 flows obliquely upward under the guidance of the flow guide side wall 201 and escapes from the top layer of the raw material to be processed, and the upward gas flow that escapes from the top layer of the raw material to be processed reaches the position where the seed crystal is located and sublimes and crystallizes, so as to generate silicon carbide crystals.

[0034] The graphite crucible in the embodiment has a simple structure, and the flow guide side wall 201 guides the upward gas flow from the inside to the outside and obliquely upward, so that the upward gas flow on the radial inside and at the lower part of the containing space 101 flows more and more smoothly to the top of the containing space 101, improves the growth interface of the silicon carbide crystals, improves the generation quality of the silicon carbide crystals, and is beneficial to alleviate the situation that the material to be processed is hardened.

[0035] In an embodiment of the present application, as shown in Figures 4-6 The peripheral wall of the flow guide cylinder 2 has a plurality of (such as 4) air holes 202 distributed in the circumferential direction, and specifically, the inside of the flow guide cylinder 2 forms a containing cavity 204, and the containing cavity 204 can communicate with the containing space 101 between the flow guide cylinder 2 and the crucible body 1 through the air holes 202, and the above-mentioned arrangement can make part of the upward gas flow generated by the raw material to be processed in the containing space 101 between the flow guide cylinder 2 and the crucible body 1 pass through each air hole 202 and enter the containing cavity 204 inside the flow guide cylinder 2, so as to maintain the gaseous density inside the flow guide cylinder 2.

[0036] In an embodiment of the present application, a plurality of groups of ventilation holes are formed on the peripheral wall of the draft tube 2, each group of ventilation holes comprising a plurality of ventilation holes 202 distributed along the circumferential direction. Specifically, three groups of ventilation holes are formed on the draft tube 2 in the present embodiment, each group of ventilation holes comprising four ventilation holes 202 distributed along the circumferential direction. The arrangement of the ventilation holes facilitates the upward flow of the ascending gas generated in the radial direction to enter the accommodation cavity 204 of the draft tube 2, thereby further improving the maintenance of the gaseous density in the draft tube 2. Further, the height between the group of ventilation holes at the highest position of the draft tube 2 and the feeding opening 103 is 20 mm.

[0037] In an embodiment of the present application, as shown in Figure 1 the bottom wall of the crucible body 1 is formed with a positioning protrusion 102 protruding upward, and the bottom wall of the draft tube 2 is formed with a positioning hole 203 for the positioning protrusion 102 to be inserted into.

[0038] Specifically, the positioning protrusion 102 is in the shape of a column, and the horizontal cross-sectional shape and size of the positioning hole 203 are consistent with those of the positioning protrusion 102, so that the positioning hole 203 and the positioning protrusion 102 can be tightly assembled. The positioning protrusion 102 and the positioning hole 203 in the present embodiment serve to position the draft tube 2 during installation, thereby improving the convenience of installation of the draft tube 2 and the tightness of the connection between the draft tube 2 and the crucible body 1.

[0039] In an embodiment of the present application, the top of the crucible body 1 is formed with a feeding opening 103, and the top surface of the draft tube 2 is located below the feeding opening 103. The vertical distance between the top surface of the draft tube 2 and the feeding opening 103 is in the range of 30 cm to 50 cm. When the graphite crucible in the present embodiment is used to produce silicon carbide ingots, the distance between the top surface of the filled raw material to be processed and the feeding opening 103 is in the range of 8 cm to 12 cm. Further, the distance between the top surface of the filled raw material to be processed and the feeding opening 103 is preferably 10 cm. The seed crystal is placed above the raw material to be processed. The vertical distance between the top surface of the draft tube 2 and the feeding opening 103 in the above range can reduce or avoid affecting the temperature at the position of the seed crystal, thereby further improving the quality of the generated silicon carbide crystal.

[0040] Further, when the graphite crucible in the present embodiment is used by an operator, the difference between the filling height of the raw material to be processed in the crucible body 1 and the height of the draft tube 2 is in the range of 10 cm to 40 cm. The above numerical range can avoid affecting the surface temperature distribution and the ascending gas distribution of the raw material to be processed.

[0041] In an embodiment of the present application, the plurality of flow guide tubes 2 comprises a first flow guide tube and a second flow guide tube, the first flow guide tube is arranged at a central position inside the crucible body 1, and the second flow guide tube is arranged at the periphery of the first flow guide tube.

[0042] Further, the first flow guide tube and the second flow guide tube have the same shape and size, in the embodiment, the first flow guide tube is one, and the second flow guide tube is a plurality of, the plurality of second flow guide tubes are arranged at the periphery of the first flow guide tube and are uniformly distributed along the circumference of the first flow guide tube, and the first flow guide tube and the second flow guide tube are both formed with a flow guide side wall 201, which can further make more upward airflow generated by sublimation of the raw material at the lower part of the accommodation space 101 flow obliquely upward under the flow guide of the flow guide side wall 201 and escape from the top layer of the raw material, thereby further improving the growth interface of the silicon carbide crystal and improving the generation quality of the silicon carbide crystal.

[0043] In an embodiment of the present application, the thickness of the wall of the flow guide tube 2 is in the range of 3-5 mm, which can ensure that the flow guide tube 2 has a certain structural strength and will not be easily damaged, and can also ensure that the flow guide tube 2 has good heat transfer performance and avoids adversely affecting the sublimation of the raw material in the flow guide tube 2.

[0044] In an embodiment of the present application, the angle between the side wall of the flow guide tube 2 and the horizontal plane is in the range of 20°-60°, that is, the inclination angle of the side wall of the flow guide tube 2 in the embodiment is in the range of 20°-60°, which can ensure that the flow guide side wall 201 has good flow guide function for the upward airflow.

[0045] In an embodiment of the present application, the inner side wall of the crucible body 1 is provided with a scale (not shown in the figure) for observing the accumulation height of the raw material, which can make the operator fill the crucible body 1 with an appropriate amount of raw material more quickly and accurately, and can help to achieve a more accurate ratio of the amount of raw material and the amount of seed crystal, thereby further improving the generation quality of the crystal and the use experience of the graphite crucible.

[0046] Another embodiment of the present application provides a crystal growth device, which comprises the graphite crucible in the above embodiments.

[0047] Specifically, the crystal growth device further comprises an induction PVT silicon carbide crystal growth furnace for heating the graphite crucible.

[0048] The operator can produce a silicon carbide crystal ingot by using the graphite crucible in the above embodiments and according to the following process steps:

[0049] Step S1: the flow guide tube 2 is installed in the cleaned crucible body 1 (i.e. in the containing space 101), and the installation fit between the flow guide tube 2 and the crucible body 1 is achieved by the positioning fit between the positioning protrusions 102 and the positioning holes 203;

[0050] Step S2: the raw material to be processed is slowly filled into the containing space 101 (including the containing cavity 204), and after the filling is completed, the top surface of the raw material to be processed is 10 mm higher than the top of the flow guide tube 2;

[0051] Step S3: the seed crystal is installed, the graphite cover is installed on the top of the graphite crucible, and then the graphite crucible is installed in the induction PVT silicon carbide crystal growing furnace;

[0052] Step S4: this step is a vacuum treatment step, specifically, the graphite fiber curing felt top cover is covered, the mechanical pump and the molecular pump are opened to vacuumize the induction PVT silicon carbide crystal growing furnace, until the vacuum degree in the furnace is reduced to below 0.5 torr, then the molecular pump is closed and argon-nitrogen mixed gas is injected, the flow rate of the argon-nitrogen mixed gas is 0.02 L / min, at the same time, the proportional valve is opened to automatically set the vacuum degree in the furnace to 5 torr;

[0053] Step S5: this step is a temperature rising step, specifically, the induction PVT silicon carbide crystal growing furnace is set to a power control mode, in which the uniform speed temperature rising power is 13.5 kw, the temperature rising time is 4 h, and the holding time is 3 h;

[0054] Step S6: this step is a crystal growing step, specifically, the vacuum in the induction PVT silicon carbide crystal growing furnace is set for 30 min to reduce the vacuum degree to 1.5 torr, the uniform speed temperature rising power remains unchanged, the crystal growing starts on the seed crystal, and the crystal growing time is 72 h;

[0055] Step S7: this step is a temperature lowering step, within 5 min after the crystal growing step is completed, the vacuum degree in the induction PVT silicon carbide crystal growing furnace is increased to 450 torr, and a uniform speed temperature lowering program is set, in which the uniform speed temperature rising power is reduced from 13.5 kw to 0 within 24 h;

[0056] Step S8: this step is a furnace discharging step, after the temperature lowering is completed, argon gas is injected into the induction PVT silicon carbide crystal growing furnace to 740 torr, then the induction PVT silicon carbide crystal growing furnace is opened to take out the graphite crucible, and the graphite crucible is opened to take out the prepared silicon carbide crystal ingot.

[0057] In the description of the application, it should be understood that the terms "first", "second" are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0058] In this application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and other terms should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or communicate with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0059] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the application. In this specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0060] Although the embodiments of the application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be construed as limiting the application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the application.

Claims

1. A graphite crucible, characterized by, The graphite crucible comprises: a crucible body (1) having an inner part forming a containing space (101) for filling raw materials to be processed; a draft tube (2) arranged in the containing space (101) and in an inverted circular table shape, the draft tube (2) being formed with draft side walls (201) for guiding an upwardly and outwardly inclined draft flow generated by the raw materials to be processed after being heated.

2. The graphite crucible according to claim 1, characterized in that The draft tube (2) is provided with a plurality of air holes (202) distributed along the circumferential direction.

3. The graphite crucible according to claim 2, characterized in that The draft tube (2) is formed with a plurality of groups of air holes distributed along the generatrix direction of the draft tube (2), each group of air holes comprising a plurality of air holes (202) distributed along the circumferential direction.

4. The graphite crucible according to claim 1, wherein The bottom wall of the crucible body (1) is formed with a positioning protrusion (102) protruding upward, and the bottom wall of the draft tube (2) is formed with a positioning hole (203) for inserting the positioning protrusion (102).

5. The graphite crucible according to claim 1, wherein The top of the crucible body (1) is formed with a feeding port (103), and the vertical distance between the top surface of the draft tube (2) and the feeding port (103) ranges from 30 cm to 50 cm.

6. The graphite crucible according to claim 1, wherein The number of the draft tubes (2) is multiple, and the multiple draft tubes (2) comprise a first draft tube and a second draft tube, the first draft tube being arranged at the center position inside the crucible body (1), and the second draft tube being arranged at the periphery of the first draft tube.

7. The graphite crucible according to claim 1, wherein The thickness of the wall of the draft tube (2) ranges from 3 mm to 5 mm.

8. The graphite crucible according to claim 1, wherein The angle between the side wall of the draft tube (2) and the horizontal plane ranges from 20° to 60°.

9. The graphite crucible according to any one of claims 1 to 8, characterized in that The inner side wall of the crucible body (1) is provided with a scale for facilitating observation of the accumulation height of the raw materials to be processed.

10. A crystal growth apparatus, characterized in that, The crystal growing device comprises the graphite crucible according to any one of claims 1-9.

Images