CN211620663U

CN211620663U - Crystal growth device

Info

Publication number: CN211620663U
Application number: CN201922162910.0U
Authority: CN
Inventors: 张虎; 刘圆圆; 周敏; 郑荣庆; 高立志; 刘伟; 周国顺
Original assignee: SICC Science and Technology Co Ltd
Current assignee: Shandong Tianyue Advanced Technology Co Ltd
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2020-10-02
Anticipated expiration: 2029-12-04

Abstract

The utility model provides a crystal growth device, the device includes: the bottom of the upper crucible is provided with a plurality of upper sieve pores; the lower crucible is positioned below the upper crucible, the bottom of the lower crucible is closed, the top of the lower crucible is provided with a plurality of lower sieve holes, and the lower sieve holes and the upper sieve holes are arranged in a staggered manner; the upper crucible and the lower crucible are both arranged in the heat-preservation structure cavity; the lifting device comprises a first lifting device for controlling the upper crucible to move and a second lifting device for controlling the lower crucible to move. The device filters the powder carbonized in the crystal growth process through the upper crucible and the lower crucible and the upper sieve holes at the bottom of the upper crucible; the lower sieve mesh at the top of the lower crucible is used for collecting the carbonized powder, so that the carbonized powder is reduced from entering a gas phase component, the upper crucible is controlled to lift, the powder for crystal growth is uniformly carbonized, and the defects of inclusion, micropipes, dislocation and the like are effectively reduced.

Description

Crystal growth device

Technical Field

The utility model relates to a crystal growth device belongs to crystal growth's technical field.

Background

Silicon carbide (SiC) single crystal has excellent semiconductor physical properties such as high thermal conductivity, high breakdown voltage, extremely high carrier mobility, high chemical stability and the like, can be manufactured into high-frequency and high-power electronic devices and optoelectronic devices which work under the conditions of high temperature and strong radiation, has great application value in the fields of national defense, high technology, industrial production, power supply and power transformation, and is regarded as a third-generation wide-bandgap semiconductor material with great development prospect.

The growth process of growing the silicon carbide single crystal by the PVT method is carried out in a closed graphite crucible, so that the growth environment is in a carbon-rich atmosphere at high temperature. At the initial stage of crystal growth, the crystal growth interface is in a state of relative equilibrium of the silicon component and the carbon component because the vapor partial pressure of the silicon component is high. Along with the growth of the crystal, the silicon component in the silicon carbide raw material is continuously sublimated and reduced, the loss of silicon is gradually serious, and the powder is gradually carbonized, so that the gas-phase component in the growth chamber is gradually unbalanced and becomes a carbon-rich state. Under the growth environment rich in carbon, the front interface of the crystal growth has the enrichment of carbon and forms carbon inclusion defects. The defects of the inclusion body can induce the defects of micropipes, dislocation, stacking faults and the like, and the quality of the silicon carbide single crystal is seriously influenced. Therefore, how to prevent carbon particles in powder in the middle and later periods from entering crystals and reduce carbon coatings in the single crystals in the growth process of the silicon carbide single crystals is a technical problem which needs to be solved urgently in the growth process of the silicon carbide single crystals at present.

CN207498521U discloses a carborundum single crystal growth device of promotion quality, including graphite crucible, graphite lid and the soft felt heat preservation of graphite, the graphite lid is located graphite crucible top and seals graphite crucible, the inboard central salient region of graphite lid bonds and has the seed wafer, the cladding of the soft felt heat preservation of graphite crucible is around, top, bottom, the carborundum powder has been placed in the graphite crucible, the graphite support ring is erect to the region between carborundum powder and the seed wafer in the graphite crucible, install the draft tube on the graphite support ring, the metal filter piece of one deck or multilayer is fixed in the draft tube, evenly distributed has the through-hole in the metal filter piece. According to the method, a high-temperature-resistant metal filter and a guide cylinder are arranged in a space between the raw material and the seed crystal in the crucible, so that carbon impurities can be effectively filtered, and a carbon coating is prevented from being formed in the crystal growth process; however, the device of the patent filters carbon impurities and then enters the crucible raw material, the powder is continuously carbonized, and the carbonized powder is sublimated again along with the crucible raw material, so that the crystal growth efficiency and the crystal quality are influenced.

CN107059130B discloses a novel crucible for reducing inclusion in silicon carbide single crystal and a method for growing single crystal by using the crucible, which comprises an outer crucible and a crucible cover, wherein an inner crucible is arranged in the outer crucible, the inner crucible comprises a bottom and a side wall, the side wall is a double-layer side wall, the double-layer side wall comprises an inner wall and an outer wall, a small hole penetrating through the inner wall is arranged on the inner wall, and an annular end cover for sealing the interlayer between the inner wall and the outer wall is arranged at an upper port of the double-layer side wall. The utility model discloses an interior crucible will be in the easy carbonization's of high temperature position SiC powder and seal in the intermediate layer between the inner wall of interior crucible and the outer wall, and the small carbon particle after the powder carbonization can not be transported to the seed crystal surface, and the powder in the inner chamber plays the filtering action to the gaseous phase of pyrolysis in the intermediate layer simultaneously, has avoided the carbon particle to transmit SiC single crystal surface to the carbon inclusion in the SiC single crystal that significantly reduces. However, the patent can only prevent the micro carbon particles carbonized on the side wall of the crucible from being transported to the surface of the seed crystal, a large amount of carbonized powder is generated at the bottom of the crucible, and the micro carbon particles carbonized at the bottom of the crucible cannot be transported to the surface of the seed crystal.

SUMMERY OF THE UTILITY MODEL

In order to solve the problem, the utility model provides a crystal growth device and crystal growth method, through setting up crucible and lower crucible, go up the crucible bottom and set up the sieve mesh, filter the powder after the carbonization from the crystal growth raw materials, and make the carbonization of crystal growth raw materials even in the crystal growth process through setting up elevating gear, avoid the defect of carbon inclusion body.

The technical scheme adopted by the application is as follows:

the utility model provides a crystal growth device, the device includes:

the upper crucible is used for growing crystals, and a plurality of upper sieve pores are arranged at the bottom of the upper crucible;

the lower crucible is positioned below the upper crucible, the bottom of the lower crucible is closed, the top of the lower crucible is provided with a plurality of lower sieve holes, and the lower sieve holes and the upper sieve holes are arranged in a staggered manner;

the upper crucible and the lower crucible are both arranged in the heat-preservation structure cavity;

the lifting device comprises a first lifting device for controlling the upper crucible to move up and down and a second lifting device for controlling the lower crucible to move up and down.

Preferably, the upper sieve holes are cylindrical through holes, and/or the lower sieve holes are cylindrical through holes;

the diameter of the cylindrical through hole is 5-10 mm, and the distance between adjacent cylindrical through holes is 2-10 mm.

Preferably, the upper sieve holes are round frustum-shaped through holes, and/or the lower sieve holes are round frustum-shaped through holes;

the upper diameter of each truncated cone-shaped through hole is 2-8 mm, the lower diameter of each truncated cone-shaped through hole is 9-15 mm, and the distance between every two adjacent truncated cone-shaped through holes is 2-10 mm; the last diameter of inverted frustum-shaped through-hole is 9 ~ 15mm, and the diameter is 2 ~ 8mm down, and the distance of adjacent inverted frustum-shaped through-hole is 2 ~ 10 mm.

Preferably, the device also comprises a furnace body, the heat insulation structure is arranged inside the furnace body, and the heating device is arranged around the outside of the furnace body.

Preferably, the first lifting device comprises a first support and a first lifting platform driven by a first lead screw transmission mechanism, one end of the first support is fixed at the top of the upper crucible, and the other end of the first support sequentially penetrates through the heat insulation structure and the furnace body to be connected with the first lifting platform; and the second lifting device comprises a second support and a second lifting platform driven by a second lead screw transmission mechanism, one end of the second support is fixed at the bottom of the lower crucible, and the other end of the second support sequentially penetrates through the heat insulation structure and the furnace body to be connected with the second lifting platform.

Preferably, the first screw transmission mechanism and the second screw transmission mechanism both comprise a ball screw, a screw nut, a support and a motor, the ball screw is in threaded fit with the screw nut, the screw nut is fixedly connected with the first lifting platform or the second lifting platform, the ball screw is rotatably supported on the support, and the motor drives the ball screw to rotate through a coupler.

Preferably, the bottom of the upper crucible is provided with an upper convex column, and the upper convex column is arranged in a manner of being matched with the lower sieve hole; the top of the lower crucible is provided with a lower convex column, and the lower convex column is arranged in a matched manner with the upper sieve hole.

Preferably, the bottom of the upper crucible is provided with a downwardly extending edge baffle; and a groove guide rail extending downwards is arranged at the top end of the side wall of the lower crucible, and the edge baffle plate moves up and down in the groove guide rail.

Preferably, the upper crucible and the lower crucible are both of a cylindrical structure, the diameter of the lower crucible is the same as that of the upper crucible, and the height of the lower crucible is smaller than that of the upper crucible.

Preferably, the upper crucible and the lower crucible are both graphite crucibles, and the top of the upper crucible is bonded with seed crystals.

The utility model has the advantages that:

(1) the device of the utility model is provided with the upper crucible and the lower crucible, and the bottom of the upper crucible is provided with the upper sieve mesh, so that the powder after carbonization in the crystal growth process can be filtered; the top of the lower crucible is provided with a lower sieve mesh for collecting the carbonized powder, so that the carbonized powder is reduced from entering a gas phase component; the upper sieve mesh and the lower sieve mesh are arranged in a staggered manner, so that the carbonized powder is isolated according to the requirement; and by controlling the lifting of the upper crucible, the powder for crystal growth is uniformly carbonized, the uniformity of gas-phase components is ensured, and the defects of inclusion, micropipes, dislocation and the like are effectively reduced.

(2) The device of the utility model is simple in structure, can not only guarantee that the powder carbonization is even thorough, can also collect the powder after the carbonization at any time, improve crystal growth's quality greatly.

(3) The utility model can ensure that the upper crucible and the lower crucible are jointed and butted by controlling the lifting of the upper crucible, the powder for crystal growth is carbonized evenly and thoroughly, the proportion of carbon and silicon in the gas phase component is even, and the crystal growth defect is less; the upper crucible and the lower crucible are separated by controlling the lifting of the lower crucible, the lower crucible collects the carbonized powder, the timing switch and the closing of the upper sieve mesh and the lower sieve mesh are achieved, and the growth of high-quality crystals is realized.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a schematic structural view of a crystal growing apparatus according to the present invention;

FIG. 2 is a schematic view of a crystal growing apparatus according to the present invention in a working state;

FIG. 3 is a schematic view of a crystal growing apparatus according to the present invention;

FIG. 4 is a schematic view of an upper crucible of the apparatus of the present invention;

FIG. 5 is a schematic view of a lower crucible in the apparatus of the present invention;

wherein, 1, a furnace body; 2. a heat preservation structure; 3. an upper crucible; 31. sieving by using a sieve; 32. an upper convex column; 33. an edge baffle; 4. a lower crucible; 41. sieving holes; 42. a lower convex column; 43. a groove guide rail; 5. a first lifting device; 51. a first support; 52. a first elevating platform; 53. a first lead screw transmission mechanism; 6. a second lifting device; 61. a second support; 62. a second lifting table; 63. and the second lead screw transmission mechanism.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, the present application may be practiced in other ways than those described herein, and therefore the scope of the present application is not limited by the specific embodiments disclosed below.

In addition, in the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "coupled," and the like are to be construed broadly and include, for example, fixed or removable connections or integral parts; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Unless otherwise specified, the raw materials and reagents in the examples of the present application were purchased commercially.

The crystal growth device of the present application can be used for growing silicon carbide single crystals, but is not limited to growing silicon carbide single crystals, and the structure and the use method of the crystal growth device are described by taking silicon carbide single crystals as an example.

Referring to fig. 1 to 3, one embodiment of the present application discloses a crystal growth apparatus, including: an upper crucible 3, a lower crucible 4, a heat preservation structure 2 and a lifting device; the upper crucible 3 and the lower crucible 4 are both arranged in the cavity of the heat insulation structure 2; the upper crucible 3 is used for crystal growth, silicon carbide powder is placed in the upper crucible 3, and a plurality of upper sieve holes 31 are formed in the bottom of the upper crucible 3; the lower crucible 4 is positioned below the upper crucible 3, the bottom of the lower crucible 4 is closed, the top of the lower crucible is provided with a plurality of lower sieve holes 41, and the lower sieve holes 41 and the upper sieve holes 31 are arranged in a staggered mode. The lower crucible 4 is used for collecting the carbonized powder; the lifting device comprises a first lifting device 5 for controlling the upper crucible 3 to move up and down and a second lifting device 6 for controlling the lower crucible to move up and down. When the bottom of the upper crucible 3 is tightly attached to the top of the lower crucible 4, carbonized powder is gradually generated along with the heating process in the crystal growth process in the upper crucible 3; when the bottom of the upper crucible 3 is separated from the top of the lower crucible 4, the carbonized powder in the upper crucible 3 falls into the inside of the lower crucible 4 through the upper sieve holes 31 of the upper crucible 3 and the lower sieve holes 41 of the lower crucible 4, so that the carbonized powder in the upper crucible 3 is filtered from the powder required for crystal growth. And through setting up the first elevating gear 5 that control upper crucible 3 reciprocated for the brilliant in-process of growing, upper crucible 3 can reciprocate in the high temperature district, reaches that the powder carbonization is even, thorough, and the proportion of crystal growth carbon and silicon is even, and crystal growth defect is few.

In one embodiment, the upper screen 31 is a cylindrical through hole, and/or the lower screen 41 is a cylindrical through hole; preferably, the diameter of the cylindrical through hole is 5-10 mm, and the distance between adjacent cylindrical through holes is 2-10 mm. The arrangement of the cylindrical through holes ensures that the generated carbon simple substance particles after carbonization are filtered from the powder for crystal growth when the upper crucible 3 is separated from the lower crucible 4. The upper sieve hole 31 and the lower sieve hole 41 may be square holes or polygonal holes as long as the carbon particles can be filtered. In the crystal growth process, temperature difference exists in the axial direction in the crucible, the temperature is gradually reduced from the bottom to the top, the powder for crystal growth is easy to gather in the gas phase transmission process, the particle size of the powder for crystal growth is far larger than that of carbon simple substance particles, and most of the dropped powder is the carbon simple substance particles.

With combined reference to fig. 4-5, in a preferred embodiment, in order to prevent back separation of the fallen elemental carbon particles, the upper sieve holes 31 are truncated cone-shaped through holes, and/or the lower sieve holes 41 are truncated cone-shaped through holes; the upper diameter of each truncated cone-shaped through hole is 2-8 mm, the lower diameter of each truncated cone-shaped through hole is 9-15 mm, and the distance between every two adjacent truncated cone-shaped through holes is 2-10 mm; the upper diameter of each inverted circular truncated cone-shaped through hole is 9-15 mm, the lower diameter of each inverted circular truncated cone-shaped through hole is 2-8 mm, and the distance between every two adjacent circular truncated cone-shaped through holes is 2-10 mm; the upper sieve holes 31 are in the shape of round tables with narrow tops or the lower sieve holes 41 are in the shape of inverted round tables with narrow tops, so that the falling carbon simple substance particles are blocked to a certain extent, the carbon simple substance particles are effectively prevented from being separated back upwards, and the probability of the carbon components in the gas phase components is greatly reduced.

In a specific embodiment, the device comprises a furnace body 1, a heat preservation structure 2 is arranged inside the furnace body 1, a heating device is arranged around the outside of the furnace body 1, and seed crystals are bonded on the top of an upper crucible 3; the top of the heat preservation mechanism 2 is provided with a temperature measuring hole. The upper crucible 3 and the lower crucible 4 are both graphite crucibles; the crucible cover on the top of the upper crucible 3 is adhered with seed crystals.

Referring to fig. 3 in combination, in a specific embodiment, the first lifting device 5 includes a first pillar 51 and a first lifting platform 52 driven by a first lead screw transmission mechanism 53, one end of the first pillar 51 is fixed on the top of the upper crucible 3, and the other end of the first pillar 51 passes through the heat insulation structure 2 and the furnace body 1 in sequence to be connected with the first lifting platform 52; the second lifting device 6 comprises a second support 61 and a second lifting platform 62 driven by a second lead screw transmission mechanism 63, one end of the second support 61 is fixed at the bottom of the lower crucible 4, and the other end of the second support passes through the heat preservation structure 2 and the furnace body 1 in sequence to be connected with the second lifting platform 62. The first/second lifting platform is driven to ascend or descend by the first/second lead screw transmission mechanism, and the ascending or descending of the first/second lifting platform drives the ascending or descending of the upper crucible/the lower crucible.

Preferably, the first screw transmission mechanism 53 and the second screw transmission mechanism 63 both include a ball screw, a screw nut, a bracket and a motor, the ball screw is in threaded fit with the screw nut, the screw nut is fixedly connected with the first lifting platform or the second lifting platform, the ball screw is rotatably supported on the bracket, and the motor drives the ball screw to rotate through a coupler. The specific structure of the screw transmission mechanism is not limited to the above manner, and the screw transmission mechanism can drive the lifting platform and the upper crucible/the lower crucible to move up and down.

In a preferred embodiment, the bottom of the upper crucible 3 is provided with an upper convex column 32, and the upper convex column 32 is arranged in cooperation with the lower sieve hole 41; the top of the lower crucible 4 is provided with a lower convex column 42, and the lower convex column 42 is matched with the upper sieve hole 31. When the upper sieve holes 31 and the lower sieve holes 41 are cylindrical, the upper convex columns 32 and the lower convex columns 42 are cylindrical; when the upper sieve holes 31 are in the shape of a circular truncated cone and the lower sieve holes 41 are in the shape of a circular truncated cone, the upper convex columns 32 are in the shape of a circular truncated cone and the lower convex columns 32 are in the shape of a circular truncated cone. In the crystal growth process, the lower sieve holes 31 and the upper sieve holes 41 are arranged in a staggered mode, and the upper convex columns 32 and the lower convex columns 42 are arranged to realize seamless butt joint when the upper crucible and the lower crucible are closed, so that the stability of a gas phase environment in the crystal growth process is ensured.

In a preferred embodiment, the bottom of the upper crucible 3 is provided with a downwardly extending edge baffle 33; the top end of the side wall of the lower crucible 4 is provided with a groove guide rail 43 extending downwards, and the edge baffle 33 moves up and down in the groove guide rail 43. Preferably, the bottom of the upper crucible 3 can be provided with an upper sieve tray provided with upper sieve holes 31, and the edge of the upper sieve tray extends downwards to form an edge baffle 33; the top of lower crucible 4 is for offering the lower sieve dish of sieve mesh 41 down, and lower sieve dish limit is along the axial extension and the bottom butt of crucible down, and the border of lower sieve dish forms the recess guide rail 43 that supplies border baffle 33 removes with the lateral wall of crucible down. More preferably, the conventional crucible is also divided into two parts, the upper part is provided with the upper crucible 3, and the lower part is provided with the lower crucible 4. An upper sieve tray is detachably arranged at an opening at the bottom of the upper crucible 3, and the edge of the upper sieve tray extends downwards to form an edge baffle 33; the lower sieve tray is detachably arranged at the opening at the top of the lower crucible 4, the edge of the lower sieve tray extends axially to be abutted against the bottom of the lower crucible, and the edge of the lower sieve tray and the side wall of the lower crucible form a groove guide rail 43 for the movement of the edge baffle 33. The lower crucible 4 is separated from the upper crucible 3 by moving the edge baffle plate 33 up and down in the groove guide rail 43, and the carbonized powder can not be splashed outside the growth chamber in the falling process due to the edge baffle plate 33. It is particularly preferred that the lower crucible 4 is separated from the upper crucible 3 by a distance not greater than the height of the edge dam.

In the specific embodiment, the upper crucible 3 and the lower crucible 4 are both cylindrical structures, the diameter of the lower crucible 4 is the same as that of the upper crucible 3, the height of the lower crucible 4 is smaller than that of the upper crucible 3, and the height of the lower crucible 4 is preferably 1/5-1/2 of the height of the upper crucible 3. The upper crucible 3 is mainly used for crystal growth, and the lower crucible 4 is mainly used for collecting the filtered carbonized powder.

In the embodiment, the upper crucible 3 and the lower crucible 4 are both graphite crucibles, and the thermal insulation structure 2 is made of graphite felt, but the material is not limited thereto. The crucible cover on the top of the upper crucible 3 is adhered with seed crystals.

The application method of the crystal growth device can be as follows: in the crystal growth stage, the upper crucible 3 moves up and down in a high-temperature area, and the lower crucible 4 also moves synchronously to enable the bottom of the upper crucible 3 to be tightly attached to the top of the lower crucible 4, so that powder is uniformly carbonized; when the silicon-carbon ratio in the growth cavity of the upper crucible 3 is less than 1, the lower crucible 4 is independently moved downwards, so that the carbonized powder is filtered from the upper crucible 3.

In one embodiment, there is provided a method of producing a silicon carbide single crystal using the crystal growth apparatus of the reference drawing:

(1) and (3) assembling: tightly attaching an upper crucible 3 and a lower crucible 4, installing the upper crucible and the lower crucible in a heat insulation structure 2, placing the heat insulation structure 2 in a furnace body 1, and moving the upper crucible 3 to a high-temperature area;

(2) in the heating and temperature rising stage, silicon carbide raw materials are filled in the upper crucible 3, the upper crucible 3 is moved into a high-temperature region, the pressure in the cavity of the furnace body 1 is vacuumized, the pressure of the furnace body is controlled to be 5-800 mbar, the furnace temperature is raised to 2000-2500 ℃, and inert gases are introduced;

(3) a crystal growth stage: the upper crucible 3 moves up and down in a high-temperature area, and the lower crucible 4 also moves synchronously to tightly attach the bottom of the upper crucible 3 to the top of the lower crucible 4, so that the powder is uniformly carbonized; the synchronous moving speed of the upper crucible and the lower crucible is 0.5-5 mm/h; keeping the pressure and temperature unchanged, and finishing crystal growth in a crystal growth stage for 10-70 h;

(4) crystal growth stage: when the silicon-carbon ratio in the growth cavity of the upper crucible 3 is less than 1, the lower crucible 4 is independently moved downwards for 10-50 mm, the downward movement time is 2-5h, and the lower crucible 4 is separated from the upper crucible 3, so that the carbonized powder is filtered from the upper crucible; keeping the pressure and the temperature unchanged, and finishing crystal growth in a crystal growth stage for 10-50 h;

(5) and cooling the furnace body to room temperature, and opening the crucible to obtain the high-quality silicon carbide crystal.

1# to 3# of the silicon carbide single crystal is prepared according to the method, the silicon carbide single crystal 4# to 7# is prepared by respectively changing the synchronous moving speed of the upper crucible and the lower crucible and the independent moving distance of the lower crucible, and the specific process parameters of the sample are shown in table 1.

TABLE 1

With reference to table 1, the prepared silicon carbide single crystal 1# to 7# was examined for macro defects, pits, and bumps, which were defects having a planar size of 10 μm or more and a vertical size (e.g., height or depth) of several tens of nm or more, and yield, micropipes, polytypes, dislocations including screw dislocations (TSD) and planar dislocations (BPD), and inclusion body structural defects of the silicon carbide single crystal 1# to 7# were examined, and the examination results are shown in table 2.

TABLE 2

As can be seen from Table 2, the present invention reduces various defects in the silicon carbide crystal produced by controlling the rate at which the upper and lower crucibles move, and the individual movement of the lower crucible. By comparing silicon carbide single crystal # 4 with silicon carbide single crystal # 1, the various defects of the silicon carbide crystal produced were more serious without moving the lower crucible alone. Comparing the silicon carbide single crystals 4#, 5#, and 6# with the silicon carbide single crystal 1#, the silicon carbide crystal is not affected by the synchronous movement of the upper and lower crucibles, or by the movement rate set too fast or too slow, and various defects of the silicon carbide crystal are also affected significantly.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

The above description is only an example of the present application, and the protection scope of the present application is not limited by these specific examples, but is defined by the claims of the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present application should be included in the protection scope of the present application.

Claims

1. A crystal growth apparatus, comprising:

2. The crystal growth apparatus of claim 1, wherein the upper screen is a cylindrical through hole, and/or the lower screen is a cylindrical through hole;

3. The crystal growth apparatus of claim 1, wherein the upper screen openings are truncated cone shaped through holes and/or the lower screen openings are truncated cone shaped through holes;

4. The crystal growth apparatus of claim 1, further comprising a furnace body, wherein the thermal insulation structure is disposed inside the furnace body, and wherein the heating device is disposed around the outside of the furnace body.

5. The crystal growth device of claim 4, wherein the first lifting device comprises a first support and a first lifting platform driven by a first lead screw transmission mechanism, one end of the first support is fixed at the top of the upper crucible, and the other end of the first support sequentially penetrates through the heat preservation structure and the furnace body to be connected with the first lifting platform; and the second lifting device comprises a second support and a second lifting platform driven by a second lead screw transmission mechanism, one end of the second support is fixed at the bottom of the lower crucible, and the other end of the second support sequentially penetrates through the heat insulation structure and the furnace body to be connected with the second lifting platform.

6. The crystal growth device of claim 5, wherein the first screw transmission mechanism and the second screw transmission mechanism each comprise a ball screw, a screw nut, a bracket and a motor, the ball screw is in threaded fit with the screw nut, the screw nut is fixedly connected with the first lifting platform or the second lifting platform, the ball screw is rotatably supported on the bracket, and the motor drives the ball screw to rotate through a coupler.

7. The crystal growth apparatus of claim 1, wherein the bottom of the upper crucible is provided with an upper convex column, and the upper convex column is arranged in a manner of being matched with the lower sieve hole; the top of the lower crucible is provided with a lower convex column, and the lower convex column is arranged in a matched manner with the upper sieve hole.

8. The crystal growth apparatus of claim 1, wherein a bottom of the upper crucible is provided with a downwardly extending edge baffle; and a groove guide rail extending downwards is arranged at the top end of the side wall of the lower crucible, and the edge baffle plate moves up and down in the groove guide rail.

9. The crystal growth apparatus of claim 1, wherein the upper crucible and the lower crucible are both cylindrical in configuration, the lower crucible has a diameter that is the same as the diameter of the upper crucible, and the lower crucible has a height that is less than the height of the upper crucible.

10. The crystal growth apparatus of claim 1, wherein the upper crucible and the lower crucible are both graphite crucibles, and a seed crystal is bonded to the top of the upper crucible.