Growth Apparatus and Method for High-Quality Silicon Carbide Crystals

Abstract

The present invention provides a growth apparatus and method for high-quality silicon carbide crystals, and relates to the field of silicon carbide crystal growth. The apparatus includes a crucible with a seed crystal installed at the top, a heat-insulating layer installed outside the crucible, an induction coil installed around the heat-insulating layer, and an induction heating ring installed in the heat-insulating layer and around the seed crystal. The inner wall of the induction heating ring is installed at a distance from the outer wall of the crucible and is blocked by the heat-insulating layer. The apparatus and the combined method can increase the axial temperature gradient of the crucible and improve the growth rate of silicon carbide crystals by adding an induction heating ring at the top position of the crucible, changing the magnetic field at the top position of the crucible when the induction coil is energized, reducing the heat generated at the top position of the crucible, lowering the temperature, and at the same time, reducing the radial temperature gradient of the crucible and improving the growth quality of silicon carbide crystals.

Description

Technical Field

[0001] The present invention relates to the field of growth of silicon carbide crystals, and specifically to a growth apparatus and method for high-quality silicon carbide crystals.

Background Art

[0002] As a representative of the third-generation semiconductor materials, silicon carbide has excellent properties such as a large bandgap, high saturation electron mobility, high breakdown electric field strength, and high thermal conductivity, and thus is widely applied in fields such as power electronics, high-frequency devices, and optoelectronic devices.

[0003] The methods for growing silicon carbide mainly include physical vapor transport method (PVT), liquid phase epitaxy method (LPE), chemical vapor deposition method (CVD), etc. Among them, the PVT method is the most mature method. Currently, the crystal growth apparatuses used in the PVT method generally adopt two types: induction heating and resistance heating. Among them, induction heating has the advantages of simple structure, high heating efficiency, fast heating rate, and no pollution, but there are also problems that the temperature gradient is unreasonable and it affects the crystal growth rate and quality.

Summary of the Invention

[0004] An object of the present invention includes providing a growth apparatus and method for high-quality silicon carbide crystals that can effectively increase the axial temperature gradient to accelerate the crystal growth rate, and at the same time reduce the radial temperature gradient to improve the crystal growth quality.

[0005] Embodiments of the present invention can be realized as follows.

[0006] According to a first aspect, the present invention is a growth apparatus for high-quality silicon carbide crystals, comprising

[0007] a crucible with a seed crystal installed at the top,

[0008] a heat insulation layer installed outside the crucible,

[0009] An induction coil installed around the heat insulation layer,

[0010] An induction heating ring installed in the heat insulation layer and around the seed crystal, and the inner wall of the induction heating ring is installed at a distance from the outer wall of the crucible and is blocked by the heat insulation layer. A device is provided.

[0011] In an alternative embodiment, the crucible includes a discharge part and a crystal growth part connected in sequence from bottom to top. The diameter of the crystal growth part is smaller than the diameter of the discharge part in order to make the crucible stepped. The induction heating ring is installed around the crystal growth part, and the seed crystal is installed at the top of the crystal growth part.

[0012] In an alternative embodiment, along the direction from bottom to top, the inner diameter of the induction heating ring is constant or gradually increases.

[0013] In an alternative embodiment, the induction heating ring includes a first annular part and a second annular part. The first annular part is installed around the seed crystal. The outer peripheral wall of the second annular part is connected to the top of the first annular part, and the inner peripheral wall of the second annular part extends along the axis of the crucible.

[0014] In an alternative embodiment, a first chamber is installed between the top of the crucible and the heat insulation layer, and the inner peripheral wall of the second annular part extends into the first chamber.

[0015] In an alternative embodiment, the inner peripheral wall of the second annular part extends above the seed crystal.

[0016] In an alternative embodiment, along the direction from the outer peripheral wall to the inner peripheral wall, the height of the second annular part is constant or gradually decreases.

[0017] In an alternative embodiment, the high-quality silicon carbide crystal growth apparatus further includes an auxiliary heating ring located below the induction heating ring and installed around the crucible. The inner wall of the auxiliary heating ring is installed at a distance from the outer wall of the crucible. A second chamber is installed between the lower surface of the crucible and the heat insulation layer, and the auxiliary heating ring is located within the second chamber.

[0018] According to a second aspect, the present invention provides a method for growing high-quality silicon carbide crystals, based on the high-quality silicon carbide crystal growth apparatus provided by any one of the above embodiments,

[0019] placing silicon carbide powder into the crucible,

[0020] after evacuating the crucible, filling it with an inert gas,

[0021] heating the crucible by energizing the induction coil to raise the temperature inside the crucible to 2000 - 2600 °C,

[0022] re-evacuating the crucible to reduce the pressure inside the crucible to 0.01 - 4×10³ Pa,

[0023] causing the silicon carbide powder to sublime and start growing silicon carbide crystals on the seed crystal,

[0024] after growing the silicon carbide crystals for 10 - 300 h to increase the pressure inside the crucible to 5×10³ - 1×10⁵ Pa, refilling the crucible with an inert gas,

[0025] further providing a method including, after the growth of the silicon carbide crystals is completed, cutting off the induction coil, and after the temperature inside the crucible has dropped to room temperature, removing the silicon carbide crystals from the crucible.

[0026] According to the third aspect, the present invention further provides a silicon carbide crystal manufactured by using the method for growing a high-quality silicon carbide crystal of the foregoing embodiment.

[0027] The beneficial effects of the examples of the present invention include the following. For example,

[0028] This high-quality silicon carbide crystal growth apparatus includes a crucible with a seed crystal installed at the top, a heat-insulating layer installed outside the crucible, an induction coil installed around the heat-insulating layer, and an induction heating ring installed in the heat-insulating layer and around the seed crystal. The inner wall of the induction heating ring is installed at a distance from the outer wall of the crucible and is blocked by the heat-insulating layer. By adding an induction heating ring at the top position of the crucible, the magnetic field at the top position of the crucible when the induction coil is energized is changed, the heat generated at the top position of the crucible is reduced, the temperature is lowered, thereby increasing the temperature gradient in the axial direction of the crucible, improving the growth rate of the silicon carbide crystal, and at the same time reducing the temperature gradient in the radial direction of the crucible, and improving the growth quality of the silicon carbide crystal.

[0029] Correspondingly, this method for growing a high-quality silicon carbide crystal can improve the growth rate and quality of the silicon carbide crystal because the above apparatus is used.

Brief Description of the Drawings

[0030] To more clearly explain the technical solutions of the examples of the present invention, the drawings required for use in the examples will be briefly described below. However, since the following drawings only show some examples of the present invention, they should not be regarded as limiting the scope. It should be understood by those skilled in the art that other related drawings can be obtained according to these drawings without creative effort.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0031] Symbols in the drawings: 100 - crucible, 102 - discharge part, 104 - crystal growth part, 110 - seed crystal, 200 - heat insulation layer, 300 - induction coil, 400 - induction heating ring, 410 - first annular part, 420 - second annular part, 500 - first chamber, 600 - second chamber, 700 - auxiliary heating ring, 800 - silicon carbide powder.

Modes for Carrying Out the Invention

[0032] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, hereinafter, in accordance with the drawings of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described. It is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings of this specification can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided by the drawings is not intended to limit the scope of the claimed present invention, but only represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without creative efforts are included in the claims of the present invention.

[0034] It should be noted that similar symbols and characters indicate similar items in the following drawings. Therefore, once an item is defined in a certain drawing, it is not necessary to further define and explain it in subsequent drawings.

[0035] In the description of the present invention, it should be noted that terms such as "upper", "lower", "inner", and "outer" refer to the directions or positional relationships shown in the drawings, or the directions or positional relationships in which the products of the present invention are customarily arranged when in use. This is for the purpose of facilitating the description of the present invention and simplifying the explanation, and is not intended to indicate or imply that the devices or elements mentioned must have a specific orientation, be configured in a specific orientation, or be operated in a specific orientation. Therefore, it should not be understood as a limitation of the present invention.

[0036] Also, when terms such as "first" and "second" appear, they are only used for the purpose of description for differentiation, and are not understood as indicating or implying relative importance.

[0037] It should be noted that, unless there is a contradiction, the features of the embodiments of the present invention can be combined with each other.

[0038] Currently, the devices used for silicon carbide crystal growth mainly include two types of heating methods: induction heating and resistance heating. Here, induction heating utilizes the electromagnetic induction effect, uses the crucible itself as the heat source, and supplies heat for the sublimation of silicon carbide powder in the crucible. It has advantages such as simple structure, high heating efficiency, fast heating speed, and no pollution. However, due to the skin effect, the heat generated by induction heating mainly concentrates on the outer peripheral surface of the crucible. Therefore, in the process of silicon carbide crystal growth, the axial temperature gradient is small, the radial temperature gradient is too large. A small axial temperature gradient affects the growth rate of silicon carbide crystals, and a too large radial temperature gradient increases the internal stress of silicon carbide crystals, making it easy for defects such as dislocations to occur. At the same time, the risk of cracking in silicon carbide crystals increases, leading to quality problems.

[0039] Resistance heating is to heat an object to be heated by utilizing the thermal energy generated by the Joule effect when an electric current flows through a resistor. Taking a graphite heater as an example, it generates heat after passing through direct current or alternating current, and furthermore, mainly transfers heat to the crucible by thermal radiation and thermal convection. Since the heater does not come into direct contact with the crucible, the heating effect is more uniform, and the temperature gradient in the radial direction of crystal growth is significantly smaller than that of induction heating. However, its structure is complex, the cost is high, and the problem of ignition is likely to occur.

[0040] From the above, the present invention provides an apparatus and method using induction heating that can retain the advantages of induction heating, improve the crystal growth quality, and accelerate the crystal growth rate. By adding an induction heating ring to the top of the crucible in this high-quality silicon carbide crystal growth apparatus, the magnetic field at the top of the crucible when the induction coil is energized is changed, thereby reducing the heat generated at the top of the crucible, lowering the temperature, increasing the temperature difference between the middle and lower parts of the crucible, thereby increasing the temperature gradient in the axial direction of the crucible, promoting the rapid growth of silicon carbide crystals, and accelerating the growth rate. At the same time, since the temperature of the outer periphery of the top of the crucible decreases, it inevitably reduces the temperature difference in the radial direction of the top of the crucible, thereby reducing the temperature gradient in the radial direction within the crucible, making it easier for the silicon carbide crystal to grow uniformly in the radial direction, and improving the growth quality.

[0041] Hereinafter, with reference to the embodiments, the structure, principle, effect of the high-quality silicon carbide crystal growth apparatus provided by the present invention and the detailed steps of the corresponding method will be described in detail with reference to the drawings.

[0042] First Embodiment

[0043] Referring to FIG. 1 or FIG. 2, the high-quality silicon carbide crystal growth apparatus provided by the present invention includes a crucible 100, a heat-insulating layer 200, an induction coil 300, and an induction heating ring 400.

[0044] Here, the crucible 100 is made of graphite material, and heat is generated when the induction coil 300 passes an electric current. A seed crystal 110 is installed on the inner wall of the top of the crucible 100. The fixing method of the seed crystal 110 may be bonding, clamping, etc., and is not specifically limited in this embodiment.

[0045] In this embodiment, the crucible 100 includes a discharge part 102 and a crystal growth part 104 connected in sequence from bottom to top. In order to make the crucible 100 in a stepped shape, the diameter of the crystal growth part 104 is smaller than the diameter of the discharge part 102. The crystal growth part 104 constitutes the top of the crucible 100, the discharge part 102 constitutes the middle and lower part of the crucible 100, and the seed crystal 110 is installed on the top of the crystal growth part 104 (i.e., the crucible lid). By using such a stepped structure with a small top and a large bottom, when the crucible 100 is heated, the temperature of the discharge part 102 is higher than the temperature of the crystal growth part 104, thereby improving the temperature gradient in the axial direction of the crucible 100 and increasing the growth rate of the silicon carbide crystal.

[0046] The heat insulation layer 200 is installed outside the crucible 100. Specifically, in order to slow down the heat loss of the crucible 100 as much as possible and provide the temperature environment required for the growth of the silicon carbide crystal in the crucible 100, the heat insulation layer 200 is coated on the outer wall of the crucible 100. A first chamber 500 is installed between the top of the crucible 100 and the heat insulation layer 200. Specifically, the outer surface of the top of the crystal growth part 104 does not directly contact and bond with the heat insulation layer 200, and a certain interval is provided to form the first chamber 500. By installing the first chamber 500, heat is uniformly transmitted to the top of the crystal growth part 104, thereby reducing the temperature gradient in the radial direction of the crystal growth part 104 and improving the growth quality of the silicon carbide crystal.

[0047] The material of the induction heating ring 400 is the same as that of the crucible 100, and is also made of graphite. The induction heating ring 400 is installed in the heat insulation layer 200 and around the seed crystal 110, that is, the induction heating ring 400 is installed around the crystal growth part 104. The inner wall of the induction heating ring 400 is installed at a distance from the outer wall of the crucible 100 and is blocked by the heat insulation layer 200, that is, the induction heating ring 400 is not in direct contact with the outer wall of the crucible 100, and a part of the heat insulation layer 200 is filled between the two. Since the diameter of the crystal growth part 104 is smaller than the diameter of the discharge part 102, the distance between the inner wall of the induction heating ring 400 and the outer wall of the crystal growth part 104 becomes relatively large, and the heat insulation layer 200 between the two becomes relatively thick, with a better heat insulation effect, and the heat of the induction heating ring 400 can be effectively blocked from being transmitted to the crystal growth part 104 of the crucible 100.

[0048] Furthermore, the axis of the induction heating ring 400 coincides with the axis of the crucible 100. In this way, each part of the induction heating ring 400 is at the same distance from the corresponding part in the radial direction of the outer wall of the crucible 100, so that the magnetic field at different positions in the circumferential direction of the top of the crucible 100 can be uniformly changed. Furthermore, the heat in the circumferential direction of the top of the crucible 100 can be uniformly reduced, the temperature can be uniformly decreased, and in this way, different parts in the circumferential direction of the silicon carbide crystal on the seed crystal 110 can be uniformly grown to improve the growth quality.

[0049] It may be necessary to install the specific structure of the induction heating ring 400. Referring further to FIG. 1, in this embodiment, along the direction from bottom to top, the inner diameter of the induction heating ring 400 is constant, that is, the whole induction heating ring 400 presents a hollow cylindrical shape, and its extending direction is parallel to the extending direction of its own axis or the axis of the crucible 100. It should be noted that referring further to FIG. 2, in this embodiment, the inner diameter of the induction heating ring 400 can also gradually increase along the direction from bottom to top, that is, the whole induction heating ring 400 presents an inverted hollow frustum shape, and its extending direction has an angle with its own axis or the axis of the crucible 100. The specific magnitude of the angle can be set as required, for example, 5 to 15°. In this way, the part of the crucible 100 surrounded by the induction heating ring 400 can gradually reduce the generated heat and gradually lower the temperature along the direction from bottom to top, that is, the part of the crucible 100 surrounded by the induction heating ring 400 also has a temperature gradient in the axial direction. In this way, the axial temperature gradient of the whole crucible 100 can be further improved, thereby increasing the growth rate on the seed crystal 110 of the silicon carbide crystal.

[0050] To be connected to a power source and pass an electric current, the induction coil 300 is installed around the heat preservation layer 200, thereby generating heat in the crucible 100 and the induction heating ring 400 by using the electromagnetic induction effect.

[0051] The operating principle and process of this high-quality silicon carbide crystal growth device are specifically as follows.

[0052] When a current is passed through the induction coil 300, due to the electromagnetic induction effect, heat is generated in the crucible 100, which itself becomes a heat source. Thereby, the silicon carbide powder 800 in the crucible 100 sublimes to form a vapor-phase crystal growth component (mainly SimCn). After the vapor-phase crystal growth component rises, silicon carbide crystals are formed on the seed crystal 110. On the other hand, by installing the induction heating ring 400, the magnetic field at the top of the crucible 100 can be changed. The heat generated at the top of the crucible 100 decreases compared to the middle and lower parts where the induction heating ring 400 is not installed. That is, the heat generated in the crystal growth part 104 decreases compared to the discharge part 102 (due to the skin effect of induction heating, the eddy current induced at the top of the heat field is mainly in the induction heating ring 400. Therefore, the Joule heat generated in the induction heating ring 400 is much more than the Joule heat in the region where the crystal growth part 104 is located. And between the induction heating ring 400 and the crystal growth part 104 is blocked by the heat insulation layer 200. When the heat generated in the induction heating ring 400 is transmitted to the crystal growth part 104, it decreases significantly. Therefore, the heat of the crystal growth part 104 mainly comes from the heat transfer of the discharge part 102, and the heat generated in the crystal growth part 104 inevitably decreases), thereby making the temperature of the crystal growth part 104 lower than the temperature of the discharge part 102, increasing the axial temperature difference of the crucible 100, that is, increasing the axial temperature gradient of the crucible 100, and further effectively increasing the growth rate on the seed crystal 110 of the silicon carbide crystal. At the same time, the decrease in the temperature of the outer periphery at the top of the crucible 100 also inevitably reduces the temperature difference between different parts in the radial direction at the top of the crucible 100, thereby reducing the radial temperature gradient of the crucible 100, enabling different parts in the radial direction of the silicon carbide crystal to grow uniformly, and improving the growth quality of the silicon carbide crystal.

[0053] This high-quality silicon carbide crystal growth apparatus can change the magnetic field at the top of the crucible 100 by installing an induction heating ring 400 around the top of the crucible 100, thereby reducing the heat generated at the top of the crucible 100, making the temperature at the top of the crucible 100 lower than the temperature in the middle and lower parts of the crucible 100. That is, the temperature of the crystal growth part 104 is lower than the temperature of the discharge part 102. In this way, the temperature gradient in the axial direction of the crucible 100 can be increased, thereby effectively accelerating the growth rate of the silicon carbide crystal. At the same time, the temperature gradient in the radial direction of the crucible 100 can be reduced, thereby improving the growth quality of the silicon carbide crystal.

[0054] Second Embodiment

[0055] The overall structure, operating principle, and technical effects obtained of the high-quality silicon carbide crystal growth apparatus provided by this embodiment are basically the same as those of the first embodiment, and the difference lies in the specific structure of the induction heating ring 400.

[0056] Referring to FIG. 3 or FIG. 4, in this embodiment, the induction heating ring 400 includes a first annular part 410 and a second annular part 420. The first annular part 410 is installed around the seed crystal 110, that is, the first annular part 410 is installed around the crystal growth part 104. The axis of the first annular part 410 coincides with the axis of the crucible 100, and the inner wall of the first annular part 410 is installed at a distance from the outer wall of the crucible 100 and is blocked by the heat insulation layer 200.

[0057] The axis of the second annular part 420 also coincides with the axis of the crucible 100, and the entire second annular part 420 is located above the crystal growth part 104. The outer peripheral wall of the second annular part 420 is connected to the top of the first annular part 410. The inner peripheral wall of the second annular part 420 extends towards the axis of the crucible 100, and the induction heating ring 400 presents a substantially inverted "L" shape in the cross-section at any position in the circumferential direction. Its first annular part 410 faces the circumferential surface of the crystal growth part 104 in the radial direction, and the second annular part 420 faces the end surface of the crystal growth part 104 in the axial direction.

[0058] The relative positions of the first annular part 410 and the second annular part 420 can be set as required. Further referring to FIG. 3, in this embodiment, the first annular part 410 is in a hollow cylindrical shape, and its extending direction is parallel to its own axis or the axis of the crucible 100. The inner peripheral wall of the second annular part 420 extends into the first chamber 500 and extends above the seed crystal 110. Along the direction from the outer peripheral wall of the second annular part 420 to the inner peripheral wall of the second annular part 420, the height of the second annular part 420 is constant, that is, the second annular part 420 extends horizontally, and its extending direction is perpendicular to its own axis or the axis of the crucible 100.

[0059] When using the induction heating ring 400 with such a structure, its second annular part 420 can adjust the heat transfer effect from the first annular part 410 to the crystal growth part 104. When the first annular part 410 becomes the first heat source, the second annular part 420 becomes the second heat source. Therefore, by setting the shape and size of the second annular part 420, the temperature gradient in the radial direction of the crystal growth part 104 can be adjusted, and a small temperature gradient can be maintained in the crystal growth part 104. Theoretically, the smaller the temperature gradient in the radial direction, the better the growth quality of the silicon carbide crystal. However, when the temperature gradient in the radial direction becomes small to a certain extent, the crystal growth part 104 needs to maintain a certain temperature gradient in the radial direction according to the actual needs to better control the growth shape of the silicon carbide crystal, thereby further improving the growth quality of the silicon carbide crystal.

[0060] It should be noted that further referring to FIG. 4, in this embodiment, the second annular part 420 can also be in an inverted hollow frustum shape, and its extending direction has an angle less than 90° with its own axis or the axis of the crucible 100, for example, it can be 75° - 85°. In this way, the temperature gradient in the radial direction of the crystal growth part 104 can be adjusted as required to control the growth shape of the silicon carbide crystal and further improve the growth quality of the silicon carbide crystal.

[0061] The connection method between the first annular part 410 and the second annular part 420 can also be installed as required. In this embodiment, the first annular part 410 and the second annular part 420 have a split structure and are connected by a connecting member. In other embodiments, they can also be integrally formed.

[0062] The Third Embodiment

[0063] The overall structure, operating principle, and technical effects obtained of the high-quality silicon carbide crystal growth apparatus provided by this embodiment are basically the same as those of the first embodiment or the second embodiment. The difference is that the apparatus provided by this embodiment further includes an auxiliary heating ring 700, and the diameter of the crucible 100 is the same from bottom to top and is not stepped.

[0064] Referring to FIG. 5, in this embodiment, the auxiliary heating ring 700 is located below the induction heating ring 400 and is installed around the crucible 100. The inner wall of the auxiliary heating ring 700 is installed at an interval from the outer wall of the crucible 100. The material of the auxiliary heating ring 700 is the same as that of the crucible 100 or the induction heating ring 400, also made of graphite material, in order to generate heat when the induction coil 300 is energized. The number of the auxiliary heating rings 700 can be set as required. In this embodiment, only one auxiliary heating ring 700 is installed, and its bottom extends to a position lower than the bottom of the crucible 100.

[0065] In other embodiments, the auxiliary heating ring 700 may be a plurality, such as two or three. The plurality of auxiliary heating rings 700 are installed at intervals along the axis of the crucible 100. The plurality of auxiliary heating rings 700 cooperate to realize independent heating of different parts in the axial direction of the crucible 100, and can achieve an effect similar to independent heating using a plurality of heaters. Moreover, it can avoid the disadvantages that the structure of the device in conventional resistance heating is complex and it is prone to ignition in a low-pressure environment, has high heating efficiency, and is beneficial for cost reduction.

[0066] Furthermore, in order to improve the heating uniformity at the lower part of the crucible 100, in this embodiment, a second chamber 600 is installed between the lower surface of the crucible 100 and the heat insulation layer 200. The second chamber 600 surrounds the outer surface of the lower part of the side wall and the outer surface of the bottom wall of the crucible 100. The auxiliary heating ring 700 is located within the second chamber 600 and is fixed by a mounting bracket (not shown). With such an installation, the characteristic that the thermal conductivity coefficient of the gas is low can be utilized. The heat generated by the auxiliary heating ring 700 can be uniformly transmitted to different parts in the middle and lower parts of the crucible 100 through the gas (mainly Ar, N2, vapor-phase crystal growth components, etc.) within the second chamber 600, thereby improving the temperature uniformity of different parts in the middle and lower parts of the crucible 100, reducing the temperature gradient in the radial direction of the crucible 100, and improving the growth quality of the silicon carbide crystal. At the same time, with such an installation, the heating effect on the silicon carbide powder 800 near the central position within the crucible 100 can be improved, and the utilization rate of the silicon carbide powder 800 can also be improved.

[0067] It should be noted that in other embodiments, in order to further improve the heating effect on the central position at the bottom of the crucible 100, an auxiliary heating plate (not shown) can also be installed at an interval below the bottom of the crucible 100, thereby increasing the temperature at the central position at the bottom of the crucible 100, further improving the heating effect on the silicon carbide powder 800 at the central position of the crucible 100, and increasing the utilization rate of the silicon carbide powder 800.

[0068] Also, it should be noted that in order to further increase the temperature gradient in the axial direction of the crucible 100, the crucible 100 in this embodiment may use the stepped shape in the first embodiment or the second embodiment, specifically, it can be determined according to actual needs.

[0069] Fourth Embodiment

[0070] The embodiments of the present invention are methods for growing high-quality silicon carbide crystals. Based on the devices provided by the first embodiment, the second embodiment, or the third embodiment, specifically,

[0071] The step of putting silicon carbide powder 800 into crucible 100,

[0072] After evacuating crucible 100, the step of filling it with an inert gas,

[0073] The step of energizing induction coil 300 to heat crucible 100 in order to raise the temperature inside crucible 100 to 2000 - 2600 °C,

[0074] The step of re - evacuating crucible 100 in order to reduce the pressure inside crucible 100 to 0.01 - 4E3 Pa,

[0075] The step where silicon carbide powder 800 sublimes and silicon carbide crystals begin to grow on seed crystal 110,

[0076] The step of growing silicon carbide crystals for 10 - 300 h and then refilling crucible 100 with an inert gas in order to raise the pressure inside crucible 100 to 5E3 - 1E5 Pa,

[0077] After the growth of silicon carbide crystals is completed, cutting off induction coil 300, and after the temperature inside crucible 100 drops to room temperature, taking out the silicon carbide crystals from crucible 100, a method is provided.

[0078] Here, the speed control of exhaust and intake is realized by a mechanical pump, a butterfly valve and a flow meter combined.

[0079] Example 5:

[0080] The embodiment of the present invention provides a silicon carbide crystal (i.e., ingot) manufactured using the method for growing high - quality silicon carbide crystals provided by the fourth embodiment, which has the characteristics of few defects and high quality.

[0081] The above are only specific embodiments of the present invention, but the scope of the claims of the present invention is not limited thereto. Those skilled in the art can easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and all of them are included in the scope of the claims of the present invention.

Claims

1. A growth apparatus for high-quality silicon carbide crystals, comprising: a crucible (100) having a seed crystal (110) installed at the top; a heat-insulating layer (200) installed outside the crucible (100); an induction coil (300) installed around the heat-insulating layer (200); an induction heating ring (400) installed within the heat-insulating layer (200) and around the seed crystal (110); the inner wall of the induction heating ring (400) is installed at a distance from the outer wall of the crucible (100) and is blocked by the heat-insulating layer (200); the induction heating ring (400) includes a first annular portion (410) and a second annular portion (420), the first annular portion (410) is installed around the seed crystal (110), the outer peripheral wall of the second annular portion (420) is connected to the top of the first annular portion (410), and the inner peripheral wall of the second annular portion (420) extends toward the axis of the crucible (100); A growth apparatus for high-quality silicon carbide crystals, characterized in that.

2. The crucible (100) includes a discharge portion (102) and a crystal growth portion (104) connected in sequence from bottom to top. To make the crucible (100) stepped, the diameter of the crystal growth portion (104) is smaller than the diameter of the discharge portion (102). The induction heating ring (400) is installed around the crystal growth portion (104), and the seed crystal (110) is installed at the top of the crystal growth portion (104). The growth apparatus for high-quality silicon carbide crystals according to Claim 1, characterized in that.

3. Along the direction from bottom to top, the inner diameter of the induction heating ring (400) is constant or gradually increases. The growth apparatus for high-quality silicon carbide crystals according to Claim 1, characterized in that.

4. A first chamber (500) is installed between the top of the crucible (100) and the heat-insulating layer (200), and the inner peripheral wall of the second annular portion (420) extends into the first chamber (500). The growth apparatus for high-quality silicon carbide crystals according to Claim 1, characterized in that.

5. The inner peripheral wall of the second annular portion (420) extends above the seed crystal (110). The growth apparatus for high-quality silicon carbide crystals according to Claim 4, characterized in that.

6. Along the direction from the outer peripheral wall to the inner peripheral wall, the height of the second annular portion (420) is constant or gradually decreases. The growth apparatus for high-quality silicon carbide crystals according to Claim 4, characterized in that.

7. It further includes an auxiliary heating ring (700) located below the induction heating ring (400) and installed around the crucible (100). The inner wall of the auxiliary heating ring (700) is installed at a distance from the outer wall of the crucible (100). A second chamber (600) is installed between the lower surface of the crucible (100) and the heat insulation layer (200). The auxiliary heating ring (700) is located within the second chamber (600). The high-quality silicon carbide crystal growth apparatus according to claim 1, characterized in that.

8. A method for growing high-quality silicon carbide crystals, Based on the high-quality silicon carbide crystal growth apparatus according to claim 1, Putting silicon carbide powder (800) into the crucible (100), After evacuating the crucible (100), filling it with an inert gas, Passing an electric current through the induction coil (300) to heat the crucible (100) in order to raise the temperature inside the crucible (100) to 2000 - 2600 °C, Re-evacuating the crucible (100) in order to reduce the pressure inside the crucible (100) to 0.01 - 4E3 Pa, The silicon carbide powder (800) sublimates and begins to grow silicon carbide crystals on the seed crystal (110), After growing the silicon carbide crystals for 10 - 300 h, refilling the crucible (100) with an inert gas in order to raise the pressure inside the crucible (100) to 5E3 - 1E5 Pa, After the growth of the silicon carbide crystals is completed, cutting off the induction coil (300), and after the temperature inside the crucible (100) drops to room temperature, taking out the silicon carbide crystals from the crucible (100). A method characterized by the above.

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