A device and method for comparing the growth effect of silicon carbide single crystals

Abstract

The present invention discloses a device and method for comparing the growth effect of silicon carbide single crystals, which includes a graphite crucible, a graphite support, and a graphite seed crystal rod. Silicon blocks are added into the graphite crucible. By heating the graphite crucible, the silicon blocks can be melted and react with the inner wall of the graphite crucible to generate a SiC saturated solution. The bottom surface of the graphite support is provided with a plurality of fixing rings with the same center of the circle. Each fixing ring includes a plurality of fixing areas for fixing the seed crystal substrates. The number of fixing areas in adjacent two fixing rings is equal and corresponds one by one. The corresponding fixing areas in each fixing ring are located on the radius line extending outward from the center of the fixing ring. The top surface of the graphite support is connected to the graphite seed crystal rod. By lowering the graphite seed crystal rod, each seed crystal substrate fixed at the bottom of the graphite support can be brought into contact with the liquid surface of the SiC saturated solution. The present invention can reduce the time and cost for exploring the process window of SiC crystals, accelerate the process of SiC crystals from research to application, and has a simple structure and convenient operation.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor crystal growth, and particularly to a device and method for comparing the growth effects of silicon carbide single crystals. Background Art

[0002] Silicon carbide has become a new high point in global strategic competition and has broad market prospects due to its large bandgap, critical breakdown field strength, and thermal conductivity. Liquid phase epitaxy is a method for preparing high-quality silicon carbide crystals under conditions close to thermodynamic equilibrium. This method has the advantages of high growth rate, high microtube closing efficiency, and easy diameter expansion, which has attracted the research interest of many scholars. When growing SiC crystals by the liquid phase method, the seed crystal is fixed at the front end of the graphite holder. Using silicon solution as the solvent and carbon in the graphite crucible as the solute, a saturated solution of SiC is formed at a high temperature above the melting point of silicon. Subsequently, the SiC single crystal substrate is brought into contact with the liquid surface of the solution. The temperature gradient formed between the high-temperature region of the crucible wall and the low-temperature region of the seed crystal promotes the mass transfer process of carbon in the solution. The saturated solution is transported to the low-temperature end of the substrate to form a supersaturated solution, which promotes the precipitation of SiC on the surface of the substrate and grows into SiC crystals along the crystal structure direction of the substrate. However, the carbon dissolution capacity of the silicon solution is weak. At 2830 °C, the solubility of carbon in the silicon solution is only 13 at.%, and the insufficient supply of carbon elements will result in a small crystal growth rate. Usually, transition metals or rare earth elements are added to the silicon solution to increase the solubility of carbon to improve the growth rate of SiC crystals.

[0003] The quality of SiC crystals is closely related to the orientation of the seed crystal substrate and the growth conditions of the seed crystal. Optimizing process parameters requires multiple crystal growth experiments, and only one SiC ingot can be prepared in a single crystal growth experiment, resulting in a long experimental period and high experimental costs. Accelerating the optimization of the SiC crystal growth process is the key to its practical application. Therefore, there is an urgent need to provide a technology that can reduce the time and cost of exploring the process window of SiC crystals to accelerate the process of SiC crystals from research to application. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for comparing the growth effects of silicon carbide single crystals to solve the problems existing in the above-mentioned prior art, which can reduce the time and cost of exploring the process window of SiC crystals, accelerate the process of SiC crystals from research to application, and has a simple structure and convenient operation.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for comparing the growth effects of single-crystalline silicon carbide, comprising the following steps: fixing a plurality of rings of seed substrates on the surface of a graphite carrier with the same center of a circle, such that the crystal planes of the seed substrates in the same ring are different from each other or the off-axis angles are different from each other, and making the number of the seed substrates in two adjacent rings equal and corresponding one by one, the corresponding seed substrates in each ring are located on a radius line extending outward from the center of the circle, and the crystal planes of the seed substrates on the same radius line are the same or the off-axis angles are the same; raising the temperatures of the graphite crucible and the silicon block above the melting point of silicon, and simultaneously etching the graphite crucible to provide a carbon source to form a SiC saturated solution; lowering the graphite carrier to bring the seed substrates in the low-temperature region into contact with the liquid surface of the SiC saturated solution in the high-temperature region; transporting the SiC saturated solution to the low-temperature ends of the seed substrates to form a supersaturated solution; obtaining SiC crystals on each of the seed substrates; and comparing the growth conditions of the SiC crystals in the same ring and the growth conditions of the SiC crystals on the same radius line.

[0007] Preferably, when comparing, observe the surface morphology and crystal growth thickness of the SiC crystals, and evaluate the effects of different crystal planes and different growth environments on the crystal growth quality, crystal growth stability, and crystal growth rate.

[0008] Preferably, the seed substrate is a seed substrate with a regular shape, and the seed substrate is square, hexagonal, or circular. Among them, the small-sized hexagonal seed substrate is obtained by cutting the seed crystal along the crystal plane family, and the small-sized square seed substrate is obtained by cutting the seed crystal along the crystal plane family.

[0009] Preferably, the seed substrates in the same ring are evenly distributed.

[0010] Preferably, the seed substrates in the same ring are evenly distributed at an angle of 45°, 60°, or 90°.

[0011] The present invention further provides a device for comparing the growth effects of single-crystalline silicon carbide, which adopts the method for comparing the growth effects of single-crystalline silicon carbide described above, and comprises a graphite crucible, a graphite carrier, and a graphite seed crystal rod. Silicon blocks are to be added into the graphite crucible, and by heating the graphite crucible, the silicon blocks can be melted and react with the inner wall of the graphite crucible to generate a SiC saturated solution. The bottom surface of the graphite carrier is provided with a plurality of fixed rings with the same center of a circle, and each of the fixed rings includes a plurality of fixed areas for fixing the seed substrates. The number of the fixed areas in two adjacent fixed rings is equal and corresponding one by one. The corresponding fixed areas in each fixed ring are located on a radius line extending outward from the center of the fixed ring. The top surface of the graphite carrier is connected to the graphite seed crystal rod, and by lowering the graphite seed crystal rod, the seed substrates fixed at the bottom of the graphite carrier can be brought into contact with the liquid surface of the SiC saturated solution.

[0012] Preferably, the graphite crucible is wrapped with a heat insulation layer.

[0013] Preferably, the graphite support is disc-shaped, and the graphite seed crystal rod is connected to the center position of the top surface of the graphite support.

[0014] Preferably, the centers of the fixing rings coincide with the center of the bottom surface of the graphite support.

[0015] Preferably, the fixing areas in the same fixing ring are evenly distributed.

[0016] Preferably, the fixing areas in the same fixing ring are evenly distributed at an angle of 45°, 60°, or 90°.

[0017] The present invention has achieved the following technical effects compared with the prior art:

[0018] The device and method for comparing the growth effects of silicon carbide single crystals provided by the present invention are provided with multiple fixing rings with the same center on the graphite support. Each fixing ring includes multiple fixing areas for fixing the seed crystal substrate. The number of fixing areas in adjacent two fixing rings is equal and corresponds one by one. The corresponding fixing areas in each fixing ring are located on the radius line extending outward from the center of the fixing ring. By fixing the seed crystal substrate in each fixing area on the graphite support, the crystal planes of the seed crystal substrates in the same ring are different from each other or the off-axis angles are different from each other, and the number of seed crystal substrates in adjacent two rings is equal and corresponds one by one. The crystal planes of the seed crystal substrates on the same radius line are the same or the off-axis angles are the same. With this fixing method, the purpose of obtaining multiple SiC crystals in one process experiment is achieved. The structure is simple and the operation is convenient. By comparing multiple SiC crystals with different crystal planes or different off-axis angles in the same ring, the growth effects of crystals grown in different orientations can be evaluated. By comparing multiple SiC crystals with the same crystal plane or the same off-axis angle on the same radius line, the growth effects of crystals under different temperatures and flow environments can be evaluated. Multiple groups of comparisons can be carried out in one process experiment, thus greatly reducing the time and cost of exploring the SiC crystal process window and accelerating the process from research to application of SiC crystals. This method of simultaneous growth of multiple substrates ensures the consistency of the crystal growth environment in the same ring, reduces the time cost of optimizing the growth process, and significantly improves the efficiency of process exploration. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1Schematic structural diagram of the device for comparing the growth effects of silicon carbide single crystals provided by the present invention;

[0021] Figure 2 Schematic diagram of the bonding and hot pressing of the seed crystal substrate and the graphite holder in the embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the arrangement of the seed crystal substrates on the graphite holder in the second embodiment;

[0023] Figure 4 Schematic diagram of the arrangement of the seed crystal substrates on the graphite holder in the third embodiment;

[0024] Figure 5 Schematic diagram of the arrangement of the seed crystal substrates on the graphite holder in the fourth embodiment;

[0025] In the figure: 1 - graphite holder, 2 - seed crystal substrate, 3 - graphite crucible, 4 - SiC saturated solution, 5 - graphite seed crystal rod, 6 - fixed area, 7 - heat insulation layer, 8 - graphite glue, 9 - vacuum hot pressing furnace ram. Specific embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] The purpose of the present invention is to provide a device and method for comparing the growth effects of silicon carbide single crystals, so as to solve the problems existing in the prior art, reduce the time and cost of exploring the process window of SiC crystals, accelerate the process of SiC crystals from research to application, and have a simple structure and convenient operation.

[0028] In order to make the above-mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] Such as Figures 1 - 5As shown, this embodiment provides a silicon carbide single crystal growth effect comparison device, including a graphite crucible 3, a graphite holder 1 and a graphite seed crystal rod 5. The graphite crucible 3 is used to add silicon blocks. By heating the graphite crucible 3, the silicon blocks can be melted and react with the inner wall of the graphite crucible 3 to generate a SiC saturated solution 4. The bottom surface of the graphite holder 1 is provided with a plurality of fixed rings with the same center. Each fixed ring includes a plurality of fixed areas 6 for fixing the seed crystal substrate 2. The number of fixed areas 6 in two adjacent fixed rings is equal and one-to-one corresponding. The corresponding fixed areas 6 in each fixed ring are located on a radius line extending outward from the center of the fixed ring. The top surface of the graphite holder 1 is connected to the graphite seed crystal rod 5. By descending the graphite seed crystal rod 5, each seed crystal substrate 2 fixed at the bottom of the graphite holder 1 can be brought into contact with the liquid surface of the SiC saturated solution 4.

[0030] The seed crystal substrates 2 are fixed in the fixing areas 6 on the graphite holder 1, so that the crystal planes of the seed crystal substrates 2 in the same circle are different or the off-axis angles are different, and the number of the seed crystal substrates 2 in two adjacent circles is equal and one-to-one corresponding, and the crystal planes of the seed crystal substrates 2 on the same radius line are the same or the off-axis angles are the same. In this fixing manner, the purpose of obtaining multiple SiC crystals in one process experiment is achieved, the structure is simple to set, and the operation is convenient. By comparing multiple SiC crystals with different crystal planes or different off-axis angles in the same circle, the growth effects of crystals grown from different faces are evaluated, and by comparing multiple SiC crystals with the same crystal planes or the same off-axis angles on the same radius line, the crystal growth effects under different temperatures and flow environments are evaluated. Multiple groups of comparisons can be performed in one process experiment, and the effects of different faces and different growth areas on the crystal growth quality and crystal growth rate can be quickly compared through the surface morphology and crystal growth thickness of the SiC crystal, which shortens the process exploration cycle and cost by multiples, thereby greatly reducing the time and cost of exploring the SiC crystal process window, and accelerating the process from research to application of SiC crystals. The seed crystal substrate 2 is bonded to the graphite holder 1 by means of graphite glue 8 , and the graphite holder 1 and the seed crystal substrate 2 are fixed by hot pressing using a pressure head 9 of a vacuum hot pressing furnace.

[0031] In this embodiment, the graphite crucible 3 is wrapped with a heat insulating layer 7 to reduce heat loss.

[0032] In this embodiment, the graphite holder 1 is in the shape of a disc, and the graphite seed crystal rod 5 is connected to the center position of the top surface of the graphite holder 1 .

[0033] In this embodiment, the center of each fixing ring coincides with the center of the bottom surface of the graphite holder 1 .

[0034] In this embodiment, the fixing areas 6 in the same fixing circle are evenly distributed. Preferably, the fixing areas 6 in the same fixing circle are evenly distributed at an angle of 45° ( Figure 5 as shown), or evenly distributed at an angle of 60° ( Figure 4 as shown), or evenly distributed at a 90° angle ( Figure 3 shown).

[0035] Example 2

[0036] As Figure 3 shown, this embodiment provides a method for comparing the growth effect of silicon carbide single crystals: The seed crystal is cut into eight small-sized squares along the (0001), plane. Two circles of seed crystal substrates 2 are bonded to the graphite holder 1 with graphite glue 8 at the same center. Each circle of seed crystal substrates 2 includes four seed crystal substrates 2 with different crystal planes. Ensure that the four small-sized seed crystal substrates 2 in each circle are evenly distributed at a 90° angle. For each two seed crystal substrates 2 with the same crystal plane in the two circles, they are located on a radius line extending outward from the center of the graphite holder 1. Subsequently, the vacuum hot pressing furnace ram 9 is used to fix multiple small-sized seed crystal substrates 2 and the graphite holder 1 simultaneously. The temperature of the graphite crucible 3 and the silicon block is raised above the melting point of silicon, and at the same time, the inner wall of the graphite crucible 3 is corroded to provide a carbon source to form a SiC saturated solution. Subsequently, the graphite seed crystal rod 5 descends, and the SiC seed crystal substrate 2 contacts the liquid surface of the SiC saturated solution. The saturated solution is transported to the low-temperature end of the seed crystal substrate 2 to form a supersaturated solution, which promotes the precipitation of SiC on the surface of the seed crystal substrate 2 and grows into a SiC crystal along the crystal structure direction of the seed crystal substrate 2. By comparing the growth conditions of SiC crystals with four different crystal planes in the same circle and the growth conditions of SiC crystals with the same crystal plane on the same radius line, the surface morphology and crystal growth thickness of the SiC crystals are observed to quickly evaluate the effects of different crystal planes and different growth environments on the crystal growth quality, crystal growth stability, and crystal growth rate.

[0037] Example 3

[0038] As Figure 4 shown, this embodiment provides a method for comparing the growth effect of silicon carbide single crystals: The seed crystal is cut into eight small-sized squares along the (0001), The crystal plane is cut into twelve small-sized hexagons. Two rings of seed crystal substrates 2 are bonded on the graphite holder 1 with graphite glue 8 with the same center of the circle. Each ring of seed crystal substrates 2 includes six seed crystal substrates 2 with different crystal planes, ensuring that the six small-sized seed crystal substrates 2 in each ring are evenly distributed at a 60° angle. For each two seed crystal substrates 2 with the same crystal plane in the two rings, they are located on a radius line extending outward from the center of the circle on the graphite holder 1. Subsequently, the vacuum hot pressing furnace press head 9 is used to fix multiple small-sized seed crystal substrates 2 and the graphite holder 1 simultaneously. The temperature of the graphite crucible 3 and the silicon block is raised above the melting point of silicon, and at the same time, the inner wall of the graphite crucible 3 is corroded to provide a carbon source to form a SiC saturated solution. Subsequently, the graphite seed crystal rod 5 descends, and the SiC seed crystal substrate 2 contacts the liquid surface of the SiC saturated solution. The saturated solution is transported to the low-temperature end of the seed crystal substrate 2 to form a supersaturated solution, promoting the precipitation of SiC on the surface of the seed crystal substrate 2 and growing into a SiC crystal along the crystal structure direction of the seed crystal substrate 2. By comparing the growth conditions of SiC crystals with eight different crystal planes in the same ring and the growth conditions of SiC crystals with the same crystal plane on the same radius line, the surface morphology and crystal growth thickness of the SiC crystals are observed to quickly evaluate the effects of different crystal planes and different growth environments on the crystal growth quality, crystal growth stability, and crystal growth rate.

[0039] Example 4

[0040] As Figure 5 shown, this embodiment provides a method for comparing the growth effects of silicon carbide single crystals: The seed crystal is cut into sixteen small-sized circles along the (0001), crystal plane, off-axis 4°, and off-axis 8°. Two rings of seed crystal substrates 2 are bonded on the graphite holder 1 with graphite glue 8 with the same center of the circle. Each ring of seed crystal substrates 2 includes eight seed crystal substrates 2 with different crystal planes, ensuring that the eight small-sized seed crystal substrates 2 in each ring are evenly distributed at a 45° angle. For each two seed crystal substrates 2 with the same crystal plane in the two rings, they are located on a radius line extending outward from the center of the circle on the graphite holder 1. Subsequently, the vacuum hot pressing furnace press head 9 is used to fix multiple small-sized seed crystal substrates 2 and the graphite holder 1 simultaneously. The temperature of the graphite crucible 3 and the silicon block is raised above the melting point of silicon, and at the same time, the inner wall of the graphite crucible 3 is corroded to provide a carbon source to form a SiC saturated solution. Subsequently, the graphite seed crystal rod 5 descends, and the SiC seed crystal substrate 2 contacts the liquid surface of the SiC saturated solution. The saturated solution is transported to the low-temperature end of the seed crystal substrate 2 to form a supersaturated solution, promoting the precipitation of SiC on the surface of the seed crystal substrate 2 and growing into a SiC crystal along the crystal structure direction of the seed crystal substrate 2. By comparing the growth conditions of SiC crystals with eight different crystal planes in the same ring and the growth conditions of SiC crystals with the same crystal plane on the same radius line, the surface morphology and crystal growth thickness of the SiC crystals are observed to quickly evaluate the effects of different crystal planes and different growth environments on the crystal growth quality, crystal growth stability, and crystal growth rate.

[0041] In the present invention, specific examples are used to illustrate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A method for comparing the growth effect of silicon carbide single crystals, characterized in that, The method includes the following steps: fixing a plurality of rings of seed substrates on the surface of a graphite holder with the same center of a circle, such that the crystal planes of the seed substrates in the same ring are different from each other or the off-axis angles are different from each other, and making the number of the seed substrates in two adjacent rings equal and corresponding one by one, the corresponding seed substrates in each ring are located on a radius line extending outward from the center of the circle, the crystal planes of the seed substrates on the same radius line are the same or the off-axis angles are the same; raising the temperatures of the graphite crucible and the silicon block above the melting point of silicon, and simultaneously etching the graphite crucible to provide a carbon source to form a SiC saturated solution; lowering the graphite holder to make the seed substrates in the low-temperature region contact the liquid surface of the SiC saturated solution in the high-temperature region, the SiC saturated solution is transported to the low-temperature ends of the seed substrates to form a supersaturated solution, and SiC crystals are obtained on each of the seed substrates; comparing the growth conditions of the SiC crystals in the same ring and the growth conditions of the SiC crystals on the same radius line.

2. The method for comparing the growth effect of silicon carbide single crystals according to claim 1, characterized in that: When comparing, observe the surface morphology and crystal growth thickness of the SiC crystals, and evaluate the effects of different crystal planes and different growth environments on the crystal growth quality, crystal growth stability, and crystal growth rate.

3. The method for comparing the growth effect of silicon carbide single crystals according to claim 1, characterized in that: The seed substrate is a seed substrate with a regular shape, and the seed substrate is square, hexagonal, or circular.

4. The method for comparing the growth effect of silicon carbide single crystals according to claim 1, characterized in that: The seed substrates in the same ring are evenly distributed.

5. A device for comparing the growth effect of silicon carbide single crystals, characterized in that, Using the method for comparing the growth effects of single-crystal silicon carbide according to any one of claims 1 to 4, including a graphite crucible, a graphite holder, and a graphite seed rod, silicon blocks are added into the graphite crucible, and by heating the graphite crucible, the silicon blocks can be melted and react with the inner wall of the graphite crucible to generate a SiC saturated solution; the bottom surface of the graphite holder is provided with a plurality of fixing rings with the same center of a circle, each of the fixing rings includes a plurality of fixing areas for fixing the seed substrates, the number of the fixing areas in two adjacent fixing rings is equal and corresponding one by one, the corresponding fixing areas in each fixing ring are located on a radius line extending outward from the center of the fixing ring, the top surface of the graphite holder is connected to the graphite seed rod, and by lowering the graphite seed rod, the seed substrates fixed at the bottom of the graphite holder can be brought into contact with the liquid surface of the SiC saturated solution; The graphite crucible is wrapped with a heat-insulating layer; the graphite holder is disc-shaped, and the graphite seed rod is connected to the center position of the top surface of the graphite holder.

6. The device for comparing the growth effect of silicon carbide single crystals according to claim 5, characterized in that: The centers of the respective fixing rings coincide with the center of the bottom surface of the graphite holder.

7. The device for comparing the growth effect of silicon carbide single crystals according to claim 5, characterized in that: The fixing areas in the same fixing ring are evenly distributed.

8. The device for comparing the growth effect of silicon carbide single crystals according to claim 7, characterized in that: The fixing areas in the same fixing ring are evenly distributed at an angle of 45°, 60°, or 90°.

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