Thermal insulation structure and graphite crucible crystal growth furnace

Abstract

The utility model provides a heat preservation structure and a graphite crucible crystal growth furnace, and relates to the technical field of heat preservation structures. The heat preservation structure comprises a first layer, a second layer and a third layer which are sequentially nested from inside to outside, a first baffle and a second baffle are arranged at the two ends of the second layer respectively, a closed containing space is jointly defined by the inner side wall of the third layer, the outer side wall of the first layer, the first baffle and the second baffle, and the second layer is arranged in the containing space; wherein the second layer is made of a graphite soft material, and the first layer and the third layer are made of a graphite hard material. Silicon steam is prevented from volatilizing and permeating into the heat preservation structure on the outer layer of the graphite crucible, and the service life of the heat preservation structure is prolonged while the heat preservation performance of the heat preservation structure is guaranteed.

Description

Technical Field

[0001] The present disclosure relates to the technical field of thermal insulation structures, and in particular to a thermal insulation structure and a graphite crucible crystal growth furnace. Background Art

[0002] Silicon carbide (SiC), a third-generation wide-bandgap semiconductor material, boasts excellent electrical and thermal properties. Its wide bandgap, high dielectric constant, high thermal conductivity, and high saturated electron velocity make it an ideal material for high-temperature, high-frequency, high-power, and high-voltage electronic devices. Power devices fabricated on SiC crystal substrates are widely used in new energy vehicles, high-voltage power transmission, LED lighting, 5G, and aerospace.

[0003] Currently, industry generally uses medium-frequency induction heating or resistance-heating PVT (physical vapor transport) growth systems. Typically, because silicon's vapor pressure is greater than carbon's, the atmosphere within the crucible and heat field is primarily silicon-rich, with a low carbon ratio (Si / C > 1). Currently, whether using medium-frequency induction heating or resistance heating, the insulation structure of the outer layer of the graphite crucible is generally made of rolled graphite felt, which offers advantages such as excellent thermal insulation, light weight, and ease of processing.

[0004] However, as the silicon vapor evaporates, it will penetrate into the gaps in the soft felt, causing the thermal conductivity of the insulation felt to increase, leading to changes in process parameters. As the number of processes increases, the life of the soft felt will also be affected after adsorption. Usually, it needs to be replaced after 2-3 processes, which is very costly. Utility Model Content

[0005] A technical problem to be solved by the present disclosure is: how to prevent silicon vapor from volatilizing and penetrating into the insulation structure of the outer layer of the graphite crucible, thereby increasing the service life of the insulation structure while ensuring the insulation performance of the insulation structure.

[0006] To solve the above technical problems, an embodiment of the present disclosure provides a thermal insulation structure, comprising a first layer, a second layer, and a third layer nested in sequence from the inside out, wherein a first baffle and a second baffle are respectively provided at both ends of the second layer, and the inner side wall of the third layer, the outer side wall of the first layer, the first baffle and the second baffle together form a closed accommodation space, and the second layer is arranged in the accommodation space;

[0007] The second layer is made of graphite soft material, and the first layer, the third layer, the first baffle and the second baffle are made of graphite hard material.

[0008] In some embodiments, the first baffle is disposed at an end portion of the first layer, the first baffle extends beyond an outer sidewall of the first layer and contacts an end portion of the second layer;

[0009] The second baffle is arranged at the end of the third layer. The second baffle extends out of the inner side wall of the third layer and contacts the end of the second layer.

[0010] In some embodiments, the first baffle is disposed at the first end of the first layer, and the second baffle is disposed at the second end of the third layer; the first end and the second end are opposite ends.

[0011] In some embodiments, the first end of the third layer contacts the first baffle, the second end of the first layer contacts the second baffle, and the inner side wall of the third layer, the outer side wall of the first layer, the first baffle and the second baffle together form a closed accommodating space.

[0012] In some embodiments, a first annular groove is provided on the first end of the third layer, a first annular protrusion is provided on the first baffle, and the first annular groove and the first annular protrusion cooperate with each other;

[0013] A second annular groove is provided on the second end of the first layer, and a second annular protrusion is provided on the second baffle, and the second annular groove and the second annular protrusion are matched;

[0014] Alternatively, a first annular protrusion is provided on the first end of the third layer, a first annular groove is provided on the first baffle, and the first annular groove and the first annular protrusion cooperate with each other;

[0015] A second annular protrusion is provided on the second end of the first layer, and a second annular groove is provided on the second baffle, and the second annular groove matches the second annular protrusion.

[0016] In some embodiments, a graphite wire is wound around the outside of the second layer, and the second layer is fixed to the outside of the first layer through the graphite wire.

[0017] In some embodiments, a protective layer is disposed on the sidewalls of the first layer and the third layer.

[0018] In some embodiments, a first sliding groove is provided on the outer wall of the first layer, and a first sliding block is provided on the inner wall of the second layer, and the first sliding groove and the first sliding block cooperate with each other;

[0019] A second sliding groove is provided on the outer wall of the second layer, and a second sliding block is provided on the inner wall of the third layer. The second sliding block matches the second sliding groove.

[0020] In some embodiments, a logo is provided on the outer wall of the third layer.

[0021] A graphite crucible crystal growth furnace comprises the above-mentioned heat insulation structure.

[0022] Through the above technical solution, the thermal insulation structure provided by the present invention is configured such that the second layer made of a soft graphite material is arranged in a accommodating space surrounded by a first layer, a third layer, a first baffle and a second baffle made of a hard graphite material. After the silicon vapor evaporates, it is blocked by the first and third layers of the hard graphite material, thereby preventing the silicon vapor from volatilizing and penetrating into the second layer made of a soft graphite material in the middle layer with better thermal insulation effect, thereby increasing the service life of the thermal insulation structure while ensuring the thermal insulation performance of the thermal insulation structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 It is a schematic diagram of the three-dimensional exploded structure of the thermal insulation structure disclosed in the embodiment of the present disclosure;

[0025] Figure 2 It is a schematic diagram of the internal decomposition structure of the thermal insulation structure disclosed in the embodiment of the present disclosure;

[0026] Figure 3 It is a schematic diagram of the internal structure of the thermal insulation structure disclosed in the embodiment of the present disclosure.

[0027] Description of reference numerals:

[0028] 1. First layer; 2. Second layer; 3. Third layer; 4. First baffle; 5. Second baffle. DETAILED DESCRIPTION

[0029] The following embodiments of the present disclosure are further described in detail with reference to the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present disclosure, but are not intended to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0030] The present disclosure provides these embodiments in order to make this disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments should be interpreted as merely exemplary, and not as limiting.

[0031] It should be noted that, in the description of this disclosure, unless otherwise specified, "plurality" means greater than or equal to two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are intended solely to facilitate and simplify the description of this disclosure, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0032] In addition, the terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are merely used to distinguish different parts. "Perpendicular" does not mean perpendicular in the strict sense, but rather means within the tolerance range. "Parallel" does not mean parallel in the strict sense, but rather means within the tolerance range. "Include" or "comprising" and similar terms mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements.

[0033] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this disclosure depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first or second device.

[0034] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0035] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0036] Silicon carbide (SiC), a third-generation wide-bandgap semiconductor material, boasts excellent electrical and thermal properties. Its wide bandgap, high dielectric constant, high thermal conductivity, and high saturated electron velocity make it an ideal material for high-temperature, high-frequency, high-power, and high-voltage electronic devices. Power devices fabricated on SiC crystal substrates are widely used in new energy vehicles, high-voltage power transmission, LED lighting, 5G, and aerospace.

[0037] Currently, medium-frequency induction heating or resistance heating PVT (physical vapor transport) growth systems are generally used in industry. The chemical reactions produced by the decomposition of raw materials for growing silicon carbide single crystals using the PVT method are as follows:

[0038] (a)

[0039] (b)

[0040] (b)

[0041] (d)

[0042] (e)

[0043] Generally, since the vapor pressure of silicon is greater than that of carbon, the atmosphere in the crucible and the hot field is mainly silicon-rich with a lower proportion of carbon, that is, Si / C>1. Currently, whether it is medium-frequency induction heating or resistance heating, the insulation structure of the outer layer of the graphite crucible is mostly made of rolled graphite soft felt, which has the advantages of good thermal insulation performance, light weight and easy processing.

[0044] However, as the silicon vapor evaporates, it will penetrate into the gaps in the soft felt, causing the thermal conductivity of the insulation felt to increase, leading to changes in process parameters. As the number of processes increases, the life of the soft felt will also be affected after adsorption. Usually, it needs to be replaced after 2-3 processes, which is very costly.

[0045] To solve the above technical problems, an insulation structure and a graphite crucible crystal growth furnace in the embodiments of the present disclosure can prevent silicon vapor from volatilizing and penetrating into the insulation structure of the outer layer of the graphite crucible, thereby increasing the service life of the insulation structure while ensuring the insulation performance of the insulation structure.

[0046] Example 1

[0047] like Figure 1 、 Figure 2 and Figure 3 As shown, an insulation structure includes a first layer 1, a second layer 2 and a third layer 3 nested in sequence from the inside to the outside, a first baffle 4 and a second baffle 5 are respectively provided at both ends of the second layer, the inner wall of the third layer 3, the outer wall of the first layer 1, the first baffle 4 and the second baffle 5 together form a closed accommodating space, the second layer 2 is arranged in the accommodating space, and the second layer 2 is arranged in this accommodating space; wherein, the second layer 2 is made of soft graphite material, and the first layer 1, the third layer 3, the first baffle 4 and the second baffle 5 are made of hard graphite material.

[0048] Specifically, the first layer 1, the second layer 2, and the third layer 3 can be cylindrical or square. The structures of the first layer 1, the second layer 2, and the third layer 3 can match the structure of the thermal field of the graphite crucible. As long as the first layer 1, the second layer 2, and the third layer 3 can insulate the graphite crucible, the specific structures of the first layer 1, the second layer 2, and the third layer 3 are not limited.

[0049] Specifically, the soft graphite material can be soft graphite felt or graphite foam. The hard graphite material can be hard graphite felt or isostatically pressed graphite. For example, the second layer 2 can be soft graphite felt, while the first layer 1 and the third layer 3 can be hard graphite felt. Both hard and soft graphite materials have good thermal insulation properties, but soft graphite materials offer better thermal insulation properties.

[0050] Specifically, if Figure 1 As shown, the height of the first layer 1 and the third layer 3 can be greater than or equal to that of the second layer 2, thereby sandwiching the second layer 2 within the space between the first and third layers 1, 3 and preventing volatilized silicon vapor from penetrating into the gaps within the graphite soft material of the second layer 2. A first baffle 4 and a second baffle are positioned at the top and bottom of the second layer 2 to enhance the sealing effect and prevent silicon vapor from penetrating into the gaps within the graphite soft material of the second layer 2 from the top or bottom of the space. More specifically, the baffles can be integral with the first and third layers 1, 3, or separate. For example, the baffles can be sealing rings that seal against both ends of the second layer 2 after the first, second, and third layers 1, 2, and 3 are nested in sequence. The baffles can be attached to the ends of the first or third layer 1, 3, or elsewhere on the first or third layer 3. For example, when the height of the first and third layers 1, 3 is greater than that of the second layer 2, the baffles can be positioned near the center of the first or third layer 1, 3. As long as the accommodation space can accommodate the second layer 2 , the specific shape of the accommodation space is not limited.

[0051] Through the above technical solution, the thermal insulation structure provided by the present invention, by arranging the second layer 2 made of graphite soft material in the accommodating space surrounded by the first layer 1 and the third layer 3 made of graphite hard material, the silicon vapor is blocked by the graphite hard material of the first layer 1 and the third layer 3 after volatilization, thereby preventing the silicon vapor from volatilizing and penetrating into the second layer 2 made of graphite soft material with better thermal insulation effect in the middle layer, thereby increasing the service life and working performance of the thermal insulation structure, improving the crystal growth yield, and reducing manufacturing costs.

[0052] In some embodiments, the first baffle 4 is arranged at the end of the first layer 1, the first baffle 4 extends out of the outer wall of the first layer 1 and contacts the end of the second layer 2; the second baffle 5 is arranged at the end of the third layer 3, the second baffle 5 extends out of the inner wall of the third layer 3 and contacts the end of the second layer 2.

[0053] The shapes of the first baffle 4 and the second baffle 5 can be adapted to the cross-section of the accommodating space, thereby shielding both ends of the accommodating space. The first baffle 4 and the second baffle 5 can also have other shapes to partially shield the accommodating space. Specifically, the first baffle 4 and the second baffle 5 can be circular, square, or any other shape, as long as the first baffle 4 and the second baffle 5 can shield the accommodating space.

[0054] More specifically, one or two first baffles 4 can be provided, with the two first baffles 4 being respectively provided at both ends of the first layer 1 to achieve a better sealing effect. Similarly, one or two second baffles 5 can be provided, with the two second baffles 5 being respectively provided at both ends of the third layer 3, with one of the second baffles 5 being detachably connected or disconnected from the end of the third layer 3 to facilitate the installation of the second layer 2.

[0055] By providing a first baffle 4 at the end of the first layer 1 and a second baffle 5 at the end of the third layer 3, the sealing effect is enhanced, preventing silicon vapor from penetrating into the gaps in the graphite soft material of the second layer 2 from the top or bottom of the storage space. Placing the first baffle 4 and the second baffle 5 at the ends of the first layer 1 and the second layer 2 increases the volume of the storage space, thereby accommodating the larger volume of the second layer 2 and improving the thermal insulation effect.

[0056] In some embodiments, the first baffle 4 is disposed at the first end of the first layer 1 , and the second baffle 5 is disposed at the second end of the third layer 3 ; the first end and the second end are opposite ends.

[0057] like Figure 1 As shown, the first baffle 4 and the second baffle 5 are arranged at opposite ends. On the one hand, both ends of the accommodating space can be blocked to improve the sealing effect. On the other hand, when the first baffle 4 and the first layer 1 are an integral structure or the first baffle 4 is fixedly connected to the first end of the first layer 1, and the second baffle 5 and the second layer 2 are an integral structure or the second baffle 5 is fixedly connected to the second end of the second layer 2, the second layer 2 can be first sleeved on the outside of the first layer 1 and aligned with the first baffle 4, and then the third layer 3 can be sleeved from the second end to the outside of the second layer 2, thereby sealing the second layer 2 between the two baffles. While ensuring the sealing between the first baffle 4 and the first layer 1 and the second baffle 5 and the third layer 3, it also facilitates the nested installation between the first layer 1, the second layer 2 and the third layer 3.

[0058] In some embodiments, the first end of the third layer 3 contacts the first baffle 4, and the second end of the first layer 1 contacts the second baffle 5. The inner sidewall of the third layer 3, the outer sidewall of the first layer 1, the first baffle 4, and the second baffle 5 collectively form a sealed accommodation space. By collectively forming a sealed accommodation space with the inner sidewall of the third layer 3, the outer sidewall of the first layer 1, the first baffle 4, and the second baffle 5, the second layer 2 is positioned within the sealed accommodation space, thereby further preventing silicon vapor from penetrating from the accommodation space into the gaps in the graphite soft material of the second layer 2.

[0059] In some embodiments, a first annular groove is provided on the first end of the third layer 3, a first annular protrusion is provided on the first baffle 4, and the first annular groove and the first annular protrusion cooperate with each other; a second annular groove is provided on the second end of the first layer 1, a second annular protrusion is provided on the second baffle 5, and the second annular groove and the second annular protrusion cooperate with each other.

[0060] In some embodiments, a first annular protrusion may be provided on the first end of the third layer 3, a first annular groove may be provided on the first baffle 4, and the first annular groove and the first annular protrusion may cooperate with each other; a second annular protrusion may be provided on the second end of the first layer 1, a second annular groove may be provided on the second baffle 5, and the second annular groove and the second annular protrusion may cooperate with each other.

[0061] Specifically, the shapes of the first and second annular protrusions are the same as or similar to the cross-sectional shapes of the first layer 1 or the third layer 3. For example, the first and second annular protrusions can be a circle of circular protrusions, or a circle of elliptical protrusions, or any other type of protrusion. More specifically, the cross-sectional shapes of the protrusions can be circular, triangular, square, or other shapes. The cross-sectional shapes of the first and second annular grooves correspond to the cross-sectional shapes of the first and second annular protrusions, thereby forming a sealing structure. By providing annular protrusions and annular grooves at the contact points between the first layer 1 and the second baffle, and at the contact points between the third layer 3 and the first baffle, the sealing of the accommodation space is enhanced, preventing silicon vapor from penetrating from the accommodation space into the gaps in the graphite soft material of the second layer 2.

[0062] In some embodiments, the second layer 2 is wrapped with graphite cord, securing the second layer 2 to the outside of the first layer 1. This tightly secures the second layer 2 to the outside of the first layer 1, improving structural stability. Furthermore, the graphite cord, primarily composed of graphite and possessing its thermal insulation properties, can enhance both structural stability and thermal insulation.

[0063] In some embodiments, a protective layer is provided on the sidewalls of the first layer 1 and the third layer 3. Specifically, the protective layer can be a coating sprayed on the inner wall of the first layer 1 and the outer wall of the third layer 3. More specifically, the protective layer can be carbon or silicon carbide powder to prevent silicon vapor from penetrating between the first and third layers.

[0064] In some embodiments, a first chute is provided on the outer wall of the first layer 1, and a first slider is provided on the inner wall of the second layer 2, with the first chute and the first slider cooperating with each other. A second chute is provided on the outer wall of the second layer 2, and a second slider is provided on the inner wall of the third layer 3, with the second slider cooperating with the second chute. The combination of the slider and the chute ensures a stable connection between the first, second, and third layers 1, 2, and 3. Furthermore, the chute and slider also provide guidance and positioning, allowing the first, second, and third layers 1, 2, and 3 to be nested together in the same position, ensuring a consistent thermal insulation structure.

[0065] In some embodiments, the outer wall of the third layer 3 is provided with a marking. Specifically, the marking can be a dot, a triangle, or any other arbitrary shape. The marking provided on the outer wall of the third layer 3, i.e., the outer wall of the insulation structure, corresponds to other structures in the graphite crucible crystal growth furnace, allowing the insulation structure to be installed in a fixed position, thereby improving the consistency of the insulation structure and, in turn, the quality of the silicon carbide.

[0066] Example 2

[0067] A graphite crucible crystal growth furnace includes the insulation structure of Example 1, disposed on the heat field side of the outer layer of the graphite crucible. The insulation structure utilizes an assembled structure for side insulation, which not only resists silicon vapor erosion but also provides excellent soft felt insulation. This increases the service life and performance of the heat field material, improves crystal growth yield, and reduces manufacturing costs.

[0068] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0069] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A thermal insulation structure, characterized in that: The invention comprises a first layer (1), a second layer (2) and a third layer (3) which are nested in sequence from the inside to the outside, wherein a first baffle (4) and a second baffle (5) are respectively provided at both ends of the second layer, and the inner side wall of the third layer (3), the outer side wall of the first layer (1), the first baffle (4) and the second baffle (5) together form a closed accommodation space, and the second layer (2) is arranged in the accommodation space; The second layer (2) is made of a soft graphite material, and the first layer (1), the third layer (3), the first baffle (4) and the second baffle (5) are made of a hard graphite material.

2. The thermal insulation structure according to claim 1, characterized in that: The first baffle (4) is arranged at the end of the first layer (1), and the first baffle (4) extends out of the outer side wall of the first layer (1) and contacts the end of the second layer (2); The second baffle (5) is arranged at the end of the third layer (3), and the second baffle (5) extends out of the inner side wall of the third layer (3) and contacts the end of the second layer (2).

3. The thermal insulation structure according to claim 2, characterized in that: The first baffle (4) is arranged at the first end of the first layer (1), and the second baffle (5) is arranged at the second end of the third layer (3); the first end and the second end are two opposite ends.

4. The thermal insulation structure according to claim 3, characterized in that: The first end of the third layer (3) contacts the first baffle (4), and the second end of the first layer (1) contacts the second baffle (5).

5. The thermal insulation structure according to claim 4, characterized in that: A first annular groove is provided on the first end of the third layer (3), a first annular protrusion is provided on the first baffle (4), and the first annular groove and the first annular protrusion cooperate with each other; A second annular groove is provided on the second end of the first layer (1), and a second annular protrusion is provided on the second baffle (5), wherein the second annular groove and the second annular protrusion cooperate with each other; Alternatively, a first annular protrusion is provided on the first end of the third layer (3), a first annular groove is provided on the first baffle (4), and the first annular groove and the first annular protrusion cooperate with each other; A second annular protrusion is provided on the second end of the first layer (1), and a second annular groove is provided on the second baffle (5), wherein the second annular groove and the second annular protrusion cooperate with each other.

6. The thermal insulation structure according to claim 1, characterized in that: A graphite wire is wound around the outside of the second layer (2), and the second layer (2) is fixed to the outside of the first layer (1) via the graphite wire.

7. The thermal insulation structure according to claim 1, characterized in that: A protective layer is provided on the side walls of the first layer (1) and the third layer (3).

8. The thermal insulation structure according to claim 1, characterized in that: A first sliding groove is provided on the outer wall of the first layer (1), and a first sliding block is provided on the inner wall of the second layer (2), and the first sliding groove and the first sliding block cooperate with each other; A second sliding groove is provided on the outer wall of the second layer (2), and a second sliding block is provided on the inner wall of the third layer (3), and the second sliding block cooperates with the second sliding groove.

9. The thermal insulation structure according to claim 1, characterized in that: A logo is provided on the outer wall of the third layer (3).

10. A graphite crucible crystal growth furnace, characterized in that: The thermal insulation structure comprises the thermal insulation structure according to any one of claims 1 to 9.

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