A thermal insulation structure for growth chambers used in single crystal growth

Abstract

This utility model relates to the field of crystal growth technology, and more particularly to a heat preservation structure for a growth chamber used in single crystal growth. The structure includes: a reflective layer disposed on the innermost side of the heat preservation structure to reflect thermal radiation from the growth chamber and achieve heat accumulation; and a main heat preservation layer disposed outside the reflective layer to control the porosity and assist in establishing an axial temperature gradient. While effectively maintaining the axial temperature gradient of the growth chamber, waste crystallization within the heat preservation layer can be cleaned, solving the problem of short lifespan of the heat preservation layer.

Description

Technical Field

[0001] This utility model relates to the field of crystal growth technology, and in particular to a heat preservation structure for a growth chamber used in single crystal growth. Background Technology

[0002] In crystal growth furnaces, the insulation structure is used to maintain the stability of the furnace's internal thermal field temperature and participates in the formation of the thermal field. The morphology, growth rate, and growth quality of crystals such as sapphire and silicon carbide are highly dependent on the thermal field. If the thermal field is stable, the crystal growth quality is high; if the thermal field is unstable, various defects are easily generated during the crystal growth process, resulting in lower crystal growth quality. In severe cases, crystallization may occur, making crystal growth impossible. In particular, the growth time for large-diameter single crystals is relatively long. When growing large-diameter single crystals, using the insulation structure to strengthen the insulation of the low-temperature zone in the thermal field plays a crucial role in ensuring that the crystal does not crack, maintaining the growth interface temperature, and ensuring local nucleation and crystallization in the melt.

[0003] However, in existing technical solutions for silicon carbide crystal growth furnaces, after crystal growth, a large number of difficult-to-clean silicon carbide crystals exist in the micropores of the insulation layer, affecting the service life of the insulation layer. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a reflective layer and a main insulation layer. By setting up a dynamically adjustable reflective sheet and adjustment layer, the axial temperature gradient of the growth chamber can be effectively maintained, while the waste crystallization inside the insulation layer can be cleaned, thus solving the problem of short insulation layer life.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] Preferably, the heat preservation structure for the growth chamber of single crystal growth includes: A reflective layer is disposed on the innermost side of the insulation structure and is used to reflect the thermal radiation from the growth chamber, thereby accumulating heat. The main insulation layer is disposed outside the reflective layer and is used to control the porosity and assist in establishing an axial temperature gradient.

[0007] Preferably, the reflective layer includes multiple sets of reflective groups uniformly arranged around the growth chamber, each set of reflective groups including multiple horizontally rotatably connected reflective sheets arranged from top to bottom, with the inner side of the reflective sheet being a reflective surface.

[0008] Preferably, a roller is provided on the lower outer side of the reflective sheet, and a reflective film is wound on the roller. The outer end of the reflective film is fixed to a fixing rod, and the other end of the fixing rod is rotatably connected to the outer side of the reflective sheet below.

[0009] Preferably, the main insulation layer includes a fixed layer disposed outside the reflective layer and an adjustment layer disposed outside the fixed layer and rotatably connected to the fixed layer, wherein the fixed layer and the adjustment layer are provided with communicating micropores.

[0010] Preferably, the adjustment layers are arranged in multiple groups from top to bottom, and the porosity of each group of adjustment layers decreases sequentially from top to bottom.

[0011] Preferably, the adjustment layer is provided with a vertically sliding lifting frame, an air ring is fixed on the lifting frame, and an air outlet is provided inside the airflow direction, with the air outlet closely attached to the adjustment layer.

[0012] The beneficial effects of this utility model are as follows: (1) By setting a dynamically adjustable reflector, this utility model can effectively reflect thermal radiation during the crystal growth process, so that the thermal radiation can converge to the bottom of the growth furnace to form an axial temperature gradient and be dynamically adjusted during the crystal growth process. On the other hand, it can be opened so that the thermal radiation passes through the reflector layer and directly heats the insulation layer, thereby cooperating with the oxidation of crystals in the micropores of the insulation layer. (2) By setting an adjustment layer and a fixed layer, the present invention can, on the one hand, rotate the adjustment layer so that the porosity of the main insulation layer varies, thereby forming an axial temperature gradient in the growth chamber in conjunction with the reflective layer. On the other hand, the adjustment layer can be fixed so that most of the crystals remain in the fixed layer. By inputting oxygen and using high temperature conditions, the silicon carbide in the fixed layer is oxidized and blown out by wind, thus completing self-cleaning. In summary, this utility model has the advantages of simple structure and wide application, and is especially suitable for the field of crystal growth technology. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of a heat preservation structure for a growth chamber used in single crystal growth. Figure 2 A schematic cross-sectional view of a thermal insulation structure for a growth chamber used in single crystal growth. Figure 3 This is a schematic diagram of the reflective layer's state; Detailed Implementation The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," 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 this utility model and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0015] Example 1 like Figure 1 , Figure 2 As shown, a heat preservation structure for a growth chamber used in single crystal growth includes: Reflective layer 1 is disposed on the innermost side of the heat insulation structure and is used to reflect the thermal radiation of the growth chamber to achieve heat accumulation; Main insulation layer 2, which is disposed outside the reflective layer 1 and is used to control the porosity and assist in establishing an axial temperature gradient.

[0016] In this implementation, by setting up a dynamically adjustable reflective layer 1 and a main insulation layer 2, the heat radiation is concentrated and the porosity is adjusted, so that the insulation layer can better adapt to the heat distribution requirements during crystal growth and waste recycling.

[0017] In detail, during the silicon carbide crystal growth process, the heat inside the furnace exhibits a vertical temperature gradient. The heat source is located at the bottom of the furnace body and is powered by induction coils or resistance heaters, forming a high-temperature core area. The heat energy is transferred into the furnace cavity through thermal radiation and gas thermal convection.

[0018] The reflective layer 1 reflects thermal radiation to achieve heat accumulation, and together with the difference in the opening ratio of the main insulation layer 2 in the vertical direction, it helps to establish a vertical temperature gradient in the growth chamber.

[0019] Simultaneously, some of the gaseous substances in the growth chamber enter (or diffuse) the edge area of ​​the insulation material along with the airflow. The insulation material has a porous structure, allowing these gas molecules to penetrate into its pore network. Once inside, the ambient temperature is significantly lower than the temperature required to maintain a gaseous state. In this relatively low-temperature and confined pore space, these gaseous substances undergo a direct gas-solid phase transition, transforming into solid microcrystals. Because these deposits occur deep within the pores and adhere firmly to the fibers / pore walls of the insulation material, they form residues that are difficult to remove using conventional physical methods. Therefore, by setting up a reflective layer 1 and a main insulation layer 2, oxygen can be introduced into the main insulation layer 2, and with the reflective layer 1 open, heat can be transferred outwards, placing the insulation layer in a high-temperature environment for oxidation, thus cleaning the insulation layer.

[0020] Furthermore, such as Figure 2 , Figure 3 As shown, the reflective layer 1 includes multiple sets of reflective groups uniformly arranged around the growth chamber. Each set of reflective groups includes multiple horizontally rotatably connected reflective sheets 11 arranged from top to bottom, and the inner side of the reflective sheet 11 is a reflective surface.

[0021] In this embodiment, multiple sets of motor-driven reflectors 11 are provided, and the angles of each set of reflectors 11 are different. By adjusting the angle of the reflectors 11, the horizontally transmitted heat radiation is reflected to the lower part of the growth chamber, thereby achieving the accumulation of heat in the lower part of the growth chamber.

[0022] As crystal growth proceeds, the temperature at the same horizontal position in the growth chamber also needs to change accordingly. Therefore, by adjusting the angle of the reflector 11, the location where heat is concentrated is adjusted, thereby controlling the temperature.

[0023] Furthermore, such as Figure 3 As shown, a roller 12 is provided on the lower outer side of the reflective sheet 11, and a reflective film 13 is wound on the roller 12. The outer end of the reflective film 13 is fixed to a fixing rod 14, and the other end of the fixing rod 14 is rotatably connected to the outer side of the reflective sheet 11 below.

[0024] In this embodiment, since multiple sets of reflective sheets 11 are provided, there is an angle difference between them. Therefore, there is a gap between the upper reflective sheet 11 and the lower reflective sheet 11, which will cause heat loss. Therefore, a roller 12 is provided at the lower part of the upper reflective sheet 11, and a reflective film 13 is wound on the roller 12. The outer end of the reflective film 13 is fixed to the lower reflective sheet 11 by a fixing rod 14, thereby achieving the shielding and blocking of the gap in the middle of the reflective sheet 11 by the reflective film 13, reflecting the heat radiation back and reducing heat loss.

[0025] When the insulation layer is cleaned, the angle of the reflector 11 increases, and the fixing rod 14 rotates, so that the reflector film 13 is no longer attached to the lower reflector 11, allowing heat radiation to pass directly through the reflector layer 1, thereby creating a high-temperature environment inside the main insulation layer 2 to assist the oxidation reaction.

[0026] The fixed rod 14 is rotated by a motor, and the roller 12 can be automatically wound up by a motor or by setting a torsion spring. The reflective film 13 can be made of materials such as tantalum foil to form a non-radiative reflection.

[0027] Furthermore, such as Figure 1 , Figure 2 As shown, the main insulation layer 2 includes a fixed layer 21 disposed outside the reflective layer 1 and an adjustment layer 22 disposed outside the fixed layer 21 and rotatably connected to the fixed layer 21. The fixed layer 21 and the adjustment layer 22 are provided with communicating micropores.

[0028] The adjustment layers 22 are arranged in multiple groups from top to bottom, and the porosity of each group of adjustment layers 22 decreases sequentially from top to bottom.

[0029] In this embodiment, a fixed layer 21 and an adjustment layer 22 are provided, both containing micropores that are interconnected. By rotating the adjustment layer 22, the number of interconnected micropores can be controlled, thereby adjusting the porosity. The porosity decreases sequentially from top to bottom to facilitate the establishment of an axial temperature gradient. A small porosity results in insufficient heat dissipation, a weak axial temperature gradient, slowed gas phase transport, and a reduced crystal growth rate. Conversely, a high porosity leads to rapid heat dissipation, causing overcooling at the top, premature gas phase deposition, and the formation of polycrystalline structures or inclusions. Therefore, an ideal porosity needs to be set. Furthermore, as crystal growth progresses, the temperature at the same horizontal position also needs adjustment. Therefore, by dynamically adjusting the porosity in conjunction with the adjustment of the reflector 11, the temperature at various points within the growth chamber is controlled, achieving axial temperature differences. Each adjustment layer 22 is rotated by a motor.

[0030] Furthermore, such as Figure 2 As shown, the adjustment layer 22 is provided with a vertically sliding lifting frame 23, and an air ring 24 is fixed on the lifting frame 23. The air outlet is located inside the adjustment layer 22 and is in close contact with the air outlet.

[0031] In this embodiment, by setting up an up-and-down moving air ring 24, the air ring 24 outputs oxygen into the insulation layer and delivers the oxygen into the micropores, causing the silicon carbide therein to be oxidized into silicon oxide, which is then blown out by the wind, thus achieving the cleaning of the main insulation layer 2.

[0032] It should be noted that during crystal growth, the angle of the reflector 11 and the position of the adjustment layer 22 are rotated to a preset position, so that an axial temperature gradient is presented in the growth chamber, and the gradient is adjusted as the crystal growth proceeds. After the crystal growth is completed, the angle of the reflector 11 increases, and the fixing rod 14 opens the reflective film 13, so that the heat radiation passes through the reflective layer 1. At this time, the air ring 24 introduces oxygen, and the high temperature causes the crystals on the inner side of the main insulation layer 2 to oxidize and be carried out by the wind, thus completing the self-cleaning process.

[0033] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A heat preservation structure for a growth chamber used in single crystal growth, characterized in that, include: A reflective layer (1) is provided on the innermost side of the insulation structure and is used to reflect the thermal radiation of the growth chamber to achieve heat accumulation. The main insulation layer (2) is set outside the reflective layer (1) and is used to control the porosity and assist in establishing an axial temperature gradient.

2. The heat preservation structure for a growth chamber for single crystal growth according to claim 1, characterized in that, The reflective layer (1) includes multiple sets of reflective groups uniformly arranged around the growth chamber. Each set of reflective groups includes multiple horizontally rotatably connected reflective sheets (11) arranged from top to bottom. The inner side of the reflective sheet (11) is a reflective surface.

3. The heat preservation structure for a growth chamber for single crystal growth according to claim 2, characterized in that, A roller (12) is provided on the lower outer side of the reflective sheet (11), and a reflective film (13) is wound on the roller (12). The outer end of the reflective film (13) is fixed on the fixing rod (14), and the other end of the fixing rod (14) is rotatably connected to the outer side of the reflective sheet (11) below.

4. The heat preservation structure for a growth chamber for single crystal growth according to claim 1, characterized in that, The main insulation layer (2) includes a fixed layer (21) disposed outside the reflective layer (1) and an adjustment layer (22) disposed outside the fixed layer (21) and rotatably connected to the fixed layer (21). The fixed layer (21) and the adjustment layer (22) are provided with communicating micropores.

5. The heat preservation structure for a growth chamber for single crystal growth according to claim 4, characterized in that, The adjustment layer (22) is arranged in multiple groups from top to bottom, and the opening ratio of each group of adjustment layer (22) decreases sequentially from top to bottom.

6. The heat preservation structure for a growth chamber for single crystal growth according to claim 5, characterized in that, The adjustment layer (22) is provided with a vertically sliding lifting frame (23) on the outside. A wind ring (24) is fixed on the lifting frame (23). There is an air outlet inside the airflow direction, and the air outlet is close to the adjustment layer (22).

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