Angle-adjustable crucible assembly, crystal growth device and method

Abstract

The invention relates to the technical field of crystal growth, and discloses an angle-adjustable crucible assembly and a crystal growth device and method.The angle-adjustable crucible assembly comprises a crucible; and the moving assembly is connected with the crucible and is used for enabling the crucible to incline relative to the vertical direction. By using the crystal growth device, the crystal quality and the available area of the crystal can be effectively improved.

Description

Technical Field

[0001] The present application relates to the field of crystal growth technology, and in particular to an angle-adjustable crucible assembly, a crystal growth device, and a method. Background Art

[0002] Silicon carbide single crystals offer advantages such as a wide bandgap, high thermal conductivity, a high critical breakdown electric field, and a high electron saturation mobility. They are particularly well-suited for the production of high-power-density microelectronic devices and power electronics operating under extreme conditions such as high temperature, high frequency, high voltage, high power, and strong radiation. Currently, a variety of silicon carbide devices are widely used, including PiN diodes, Schottky diodes, MOSFETs, and photoconductive switches.

[0003] Physical vapor transport (PVT) has become the mainstream method for growing SiC single crystals. However, the resulting SiC single crystals still have some defects, such as stacking faults. Stacking faults, a type of surface defect in SiC crystals, can propagate into the epitaxial layer during the epitaxial growth process on the SiC substrate, thereby reducing the quality of the epitaxial layer and affecting the performance of the final SiC device. Therefore, technologies related to improving the quality of SiC single crystals and the performance of SiC devices still need to be improved.

[0004] Application Contents

[0005] The present application aims to address, at least to some extent, one of the technical problems in the related art. To this end, one object of the present application is to provide an angle-adjustable crucible assembly, a crystal growth apparatus, and a method. The crystal growth apparatus and method of the present application can effectively reduce the occurrence of stacking faults during crystal growth, thereby improving crystal quality.

[0006] In a first aspect of the present application, an angle-adjustable crucible assembly is provided, comprising:

[0007] Crucible;

[0008] A movable assembly is connected to the crucible and is used to tilt the crucible relative to the vertical direction. During the crystal growth process of off-axis seed crystals, the use of the crucible assembly with an adjustable angle in this application can not only retain the effect of using the dense step flow of off-axis seed crystals to stabilize the crystal form in the early stage of crystal growth, but also adjust the off-axis growth of the crystal to normal growth by adjusting the direction of the crucible in the later stage of crystal growth, thereby avoiding the large-scale generation of stacking fault defects, thereby significantly improving the crystal quality and increasing the available area of the crystal.

[0009] In addition, the angle-adjustable crucible assembly according to the above embodiment of the present application may also have the following additional technical features:

[0010] In some embodiments, the moving assembly includes:

[0011] A lug is provided on the outer side wall of the crucible,

[0012] a transmission shaft connected to the lug;

[0013] A driving member is connected to the transmission shaft and is used to drive the crucible to tilt relative to the vertical direction via the transmission shaft, thereby facilitating the tilting of the crucible in the vertical direction through the connection between the components.

[0014] In some embodiments, the driving member includes:

[0015] a rotating control column connected to the transmission shaft;

[0016] A motor is connected to the rotation control column and is used to drive the rotation control column to move up and down, thereby facilitating accurate and stable adjustment of the direction of the crucible.

[0017] In some embodiments, the rotation control column is connected to the transmission shaft via a hinge, thereby facilitating installation and enabling flexible rotation between the rotation control column and the transmission shaft.

[0018] In some embodiments, the crucible assembly further comprises a tray, the tray being positioned below the crucible with a gap therebetween, the tray being provided with a through hole, the rotation control post being passed through the through hole, thereby ensuring a secure connection between the various components of the crucible assembly.

[0019] In some embodiments, the crucible assembly includes two movable assemblies that are symmetrical about the central axis of the crucible. Thus, the movable assemblies simultaneously secure and adjust the crucible from both sides, further securing the crucible on the tray and facilitating stable adjustment of the angle of the crucible assembly.

[0020] In some embodiments, the crucible assembly further comprises a material bucket disposed within the crucible for containing crystal growth materials, wherein the outer surface of the bottom of the material bucket is a curved surface, thereby ensuring that the crystal growth materials face the crystal growth surface when the crucible changes direction.

[0021] In some embodiments, the crucible assembly further includes: a plurality of balls disposed between the crucible and the material barrel, thereby further ensuring that the crystal growth raw material faces the crystal growth surface.

[0022] In a second aspect of the present application, a silicon carbide crystal growing apparatus is provided, comprising the aforementioned crucible assembly. Thus, the silicon carbide crystal growing apparatus has all the features and advantages of the aforementioned crucible assembly, which will not be described in detail here.

[0023] In some embodiments, the silicon carbide crystal growth apparatus further includes:

[0024] The heating barrel has a space inside for accommodating the crucible, which helps provide continuous and uniform heat for crystal growth and creates a stable temperature environment.

[0025] In some embodiments, the moving assembly in the silicon carbide crystal growth device is connected to the crucible through the side wall of the heating barrel, thereby helping to further improve the stability of the crystal growth device.

[0026] In a third aspect of the present application, a method for growing a silicon carbide crystal is proposed, comprising:

[0027] The θ° off-axis seed crystal is placed in a horizontal direction and grown at 2010°C to 2100°C for 10 hours to 20 hours to obtain a first crystal;

[0028] Adjusting the angle of the first crystal by -θ° along the horizontal direction and growing the first crystal at 2010° C. to 2100° C. for 200 h to 250 h to obtain the silicon carbide crystal;

[0029] The horizontal direction is 0°, the side facing the seed crystal's eccentric orientation relative to the horizontal direction is positive, and the side facing the opposite direction relative to the horizontal direction is negative. Therefore, in the later stages of off-axis seed crystal growth, the seed crystal's orientation is adjusted from 4° to 0°, perpendicular to the crystal growth material, thereby changing the seed crystal's initial eccentric growth to positive growth. Under the same temperature field, the edge growth step aggregation that induces a large number of stacking fault defects is avoided, thereby significantly improving wafer quality and increasing the available wafer area. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the crystal growth edge steps in the eccentric and normal directions according to an embodiment of the present application.

[0031] Figure 2 It is a schematic structural diagram of an angle-adjustable crucible assembly according to an embodiment of the present application.

[0032] Figure 3 It is a plan view of an angle-adjustable crucible assembly according to an embodiment of the present application.

[0033] Figure 4 It is a plan view of an angle-adjustable crucible assembly according to an embodiment of the present application.

[0034] Figure 5 This is a schematic diagram of the crucible structure of an embodiment of the present application.

[0035] Figure 6 It is a plan view of a crystal growth apparatus according to one embodiment of the present application.

[0036] Figure 7 It is a structural cross-sectional view of a crystal growth device according to one embodiment of the present application.

[0037] Figure 8 This is a schematic diagram of the crystal growth process and crucible angle adjustment according to an embodiment of the present application.

[0038] Figure 9 It is a coordinate diagram of the hexagonal crystal cell.

[0039] Figure 10 This is a diagram of the slice detection results of a crystal according to an embodiment of the present application.

[0040] Figure 11 This is a slice test result diagram of a crystal of a comparative example of the present application.

[0041] Reference numerals:

[0042] 1: Crucible 2: Moving component 3: Tray 4: Bucket

[0043] 5: Crucible cover 6: Ball bearing 7: Heating barrel 8: Insulation layer

[0044] 9: Crucible body 10: Moving component

[0045] A: Lug B: Drive shaft C: Rotating control column D: Motor DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0047] This application is based on the following findings and knowledge of the applicant:

[0048] At present, in the related technology, most of the PVT crystal growth methods use eccentric seed crystals for crystal growth. This is because when using positive seed crystals for crystal growth, when the crystal plane is completely parallel to the growth direction, the "steps" of atomic accumulation are prone to random distribution or local vacancies, the initial crystal nucleus growth lacks a "guiding direction", and the atomic attachment is disorderly, resulting in easy distortion of the crystal form, increased defects, and poor stability. When using eccentric seed crystals for crystal growth, the steps on the edge of the eccentric seed crystals are relatively dense. Figure 1 a in the positive seed crystal, while the edge steps are relatively loose, refer to Figure 1 In figure b, dense steps can greatly stabilize the crystal form in the early stage of crystal growth, but in the later stage of crystal growth, the growth is biased, which makes the steps more dense, thereby increasing the probability of stacking fault defects.

[0049] Based on the above findings, the inventors considered using eccentric seed crystals for crystal growth. After the early crystal form is stable, the angle of the seed crystal can be adjusted to make it turn to forward growth, that is, the seed crystal surface is perpendicular to the sublimation direction of the raw material. This takes into account the effect of stabilizing the crystal form when using eccentric growth using dense step flow growth in the early stage, and at the same time adjusts back to the forward growth position in the middle and late stages of growth, avoiding the edge growth step aggregation under the same temperature field to induce a large number of stacking fault defects, thereby greatly improving the quality of the chip.

[0050] In view of this, the first aspect of the present application proposes an angle-adjustable crucible assembly, referring to Figure 2 , comprising: a crucible 1 and a moving assembly 2, wherein the crucible 1 is connected to the moving assembly 2, wherein the moving assembly 2 is used to tilt the crucible 1 relative to the vertical direction.

[0051] By using the angle-adjustable crucible assembly in the present application, during the crystal growth process, after the early crystal form is stabilized, the angle of the crucible in the vertical direction is adjusted by moving the assembly, thereby adjusting the angle of crystal growth and adjusting the crystal's eccentric growth to forward growth, thereby avoiding the large-scale generation of stacking fault defects, greatly improving the crystal quality, and increasing the available area of the crystal.

[0052] In some embodiments, reference Figure 2 The crucible assembly further includes: a tray 3, which is located below the crucible and is used to fix the crucible by moving the assembly.

[0053] In some embodiments, reference Figure 3 The crucible 1 includes a crucible body 9 and a crucible cover 5. The crucible cover 5 is arranged on the crucible body 9 to suppress the volatilization of crystal growth raw materials, isolate the outside air, and maintain the pressure in the crucible.

[0054] In some embodiments, reference Figure 3 The crucible assembly further includes: a material barrel 4, which is arranged in the crucible and is used to accommodate crystal growth raw materials. The material barrel can be taken out independently to facilitate the replacement of raw materials, thereby improving production efficiency.

[0055] In some embodiments, reference Figure 3 The outer surface of the bottom of the barrel is curved. Therefore, when the angle of the crucible changes, the barrel will continuously adjust its position under the action of gravity, helping the barrel to face the crystal growth surface, thereby avoiding the barrel tilting caused by the change of the crucible angle, which would affect the crystal growth.

[0056] In some embodiments, reference Figure 4The crucible assembly further includes: a plurality of balls 6, which are arranged between the crucible body 9 and the material barrel 4. Therefore, when the angle of the crucible changes, the balls will cause the material barrel to continuously adjust its position under the action of gravity, which helps the material barrel to face the crystal growth surface, thereby avoiding the material barrel tilting caused by the change in the crucible angle, which affects crystal growth. At the same time, after repeated use, the bottom of the crucible corrodes, thereby affecting the sliding of the raw materials in the material barrel. The arrangement of multiple balls between the crucible and the material barrel can basically avoid this problem, so that even if the bottom of the crucible corrodes, the position of the crucible can be continuously adjusted with the help of the balls.

[0057] In some embodiments, reference Figure 2 The moving assembly includes: a lug A disposed on the outer wall of the crucible; a drive shaft B connected to the lug; and a driving member connected to the drive shaft for driving the crucible to tilt relative to the vertical direction via the drive shaft. This facilitates vertical tilting of the crucible through the connection between the components.

[0058] Furthermore, the shape of the lug A on the side wall of the crucible is not limited, and reference is made to Figure 5 The lug can be a combination of a cylinder and a rounded rectangular prism, thereby better fitting the curved inner wall of a cavity such as a crucible, which helps to improve the structural adaptability between different components.

[0059] In some embodiments, reference Figure 2 The driving member includes a rotation control column C and a motor D. The rotation control column C is connected to the transmission shaft B. The motor D is connected to the rotation control column C and is configured to drive the rotation control column to move up and down. Specifically, the motor-driven up and down movement of the rotation control column facilitates precise positioning, ensuring more accurate movement distance of the rotation control column, thereby enabling more accurate crucible angle adjustment.

[0060] In some embodiments, reference Figure 2 The tray 3 is provided with a through hole, and the rotation control column C is passed through the through hole. Thus, through the connection between the rotation control column C, the rotation axis B and the lug A, the crucible is stably suspended and fixed above the tray.

[0061] In some embodiments, reference Figure 2 The rotating control column and the transmission shaft are connected by a hinge. This allows the rotating control column and the transmission shaft to rotate and open and close flexibly. At the same time, the hinge structure can effectively disperse the weight and external forces of the components, making the connection between the components more stable.

[0062] In some embodiments, reference Figure 2The crucible assembly includes two moving assemblies, moving assembly 2 and moving assembly 10, which are symmetrical about the central axis of the crucible. Providing moving assemblies on both sides of the crucible evenly distributes gravity, preventing a single point of support from causing the crucible assembly to lose balance and affect crystal growth.

[0063] In a second aspect of the present application, a silicon carbide crystal growth apparatus is proposed, comprising the aforementioned crucible assembly. Thus, when using the silicon carbide crystal growth apparatus for eutectic seed growth, it is possible to achieve both the effect of stabilizing the crystal form during eutectic growth using dense step flow in the early stages of crystal growth, and to simultaneously adjust the crystal back to the forward growth position in the middle and late stages of growth, thereby avoiding the generation of a large number of stacking fault defects induced by the aggregation of edge growth steps under the same temperature field, thereby significantly improving wafer quality and increasing the available wafer area.

[0064] In some embodiments, the silicon carbide crystal growth apparatus, with reference to Figure 6 The heat-generating barrel 7 is provided with a storage space for accommodating the crucible. This helps to provide continuous and uniform high-temperature energy for crystal growth, heats the crystal growth raw materials to sublime, and thus ensures normal growth of the crystal.

[0065] In some embodiments, the silicon carbide crystal growth apparatus, with reference to Figure 6 , also includes a heat preservation layer 8, which is arranged on the outer layer of the heating barrel. The heat preservation layer can reduce heat loss, help maintain a stable temperature environment in the crystal growth device, and thus promote the normal growth of the crystal.

[0066] In some embodiments, reference Figure 7 The movable component in the silicon carbide crystal growth device passes through the side wall of the heating barrel and is connected to the crucible. The movable component connects the crucible and the heating barrel, which helps to further improve the stability of the crystal growth device. At the same time, the induced heating only acts on the heating barrel, and the rotation of the crucible has little effect on the internal temperature change.

[0067] In a third aspect of the present application, a method for growing a silicon carbide crystal is proposed, comprising:

[0068] S10: placing an off-axis seed crystal with a value of θ along a horizontal direction (0°) and growing the seed crystal at 2010° C. to 2100° C. for 10 to 20 hours to obtain a first crystal.

[0069] In this step, as an example, a seed crystal with a 4° C-plane angle of <11-20> is used for crystal growth. The seed crystal is horizontally placed in a crystal growth device and grown at 2010°C to 2100°C for 8h to 10h. Specifically, the crystal growth temperature is 2010°C, 2020°C, 2023°C, 2040°C, 2050°C, 2060°C, 2070°C, 2080°C, 2090°C, 2100°C, etc., which helps provide a driving force for crystal growth. force, thereby stabilizing the crystal form in the early stage of crystal growth, which can basically avoid the influence of the stability of the crystal form due to too low temperature, and the appearance of polymorphic single crystals due to too high temperature; the growth time can be 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc. Within the above time range, the crystal structure can be basically stable, which can basically avoid the instability of the crystal structure due to too short time, and the increase in time cost due to too long time.

[0070] Specifically, refer to Figure 9 Silicon carbide crystal is a hexagonal crystal, and <11-20> is equivalent to the normal vector of (1120), that is, the antivector of a3. Therefore, the seed crystal with a 4° angle C surface to the <11-20> direction is obtained by slicing the silicon carbide crystal after deflecting it 4° along the antivector direction of a3.

[0071] S20: adjusting the angle of the first crystal to -θ°, and growing the first crystal at 2010° C. to 2100° C. for 200 h to 250 h to obtain the silicon carbide crystal.

[0072] In this step, as an example, the angle of the first crystal is adjusted by -4° in the horizontal direction so that the direction of the first crystal is completely perpendicular to the direction of sublimation of the crystal growth raw material. As a result, the crystal growth direction is changed to forward growth, and the crystal is grown at 2010°C to 2100°C for 200h to 250h. Specifically, the crystal growth temperature is 2010°C, 2020°C, 2023°C, 2040°C, 2050°C, 2060°C, 2070°C, 2080°C, 2090°C, 2100°C, etc. The above temperature range helps to provide a driving force for crystal growth and ensure the growth of crystals. Efficiency can basically avoid the problems of affecting crystal quality due to too low temperature and the occurrence of polymorphic single crystals due to too high temperature; the growth time can be 200h, 205h, 210h, 215h, 220h, 225h, 230h, 235h, 240h, 245h, 250h, etc. Within the above time range, it is helpful to obtain higher quality crystals, and basically avoid the problems of insufficient crystal size and uneven distribution of crystal impurities due to too short growth time, which cannot meet application requirements, and increased crystal defects and increased energy consumption costs due to too long growth time.

[0073] In some embodiments, the crystal growth method is implemented by the aforementioned crystal growth device, and in the initial stage of seed crystal growth with a 4° angle C plane toward the <11-20> direction, referring to Figure 8 In a, the crucible is in the horizontal direction. During the crystal growth period of 8h to 10h, the inclination angle of the crucible in the vertical direction of the crystal growth device is adjusted. Figure 8 In b1, the motor in the moving assembly 2 drives the rotary control column to move upward, causing the crucible to tilt 4° in the opposite direction of the eutectic direction. During the tilting process of the crucible, the ball between the crucible body and the barrel causes the barrel to continuously adjust its position under the action of gravity, causing the barrel to face the crystal growth surface. Figure 8 b in the figure. At this time, the seed crystal is turned from the initial 4° to 0° perpendicular to the crystal growth material, so that the crystal grows from the partial crystal direction to the normal direction. Under the same temperature field, the generation of stacking fault defects induced by the edge growth step aggregation can be basically avoided, which helps to improve the growth quality of the crystal. After adjusting the direction of the crucible, the crystal growth is continued. The crystal grows for 20 hours. Figure 8 c in the figure, continue growing for 200h~250h, refer to Figure 8 The smaller the d, the higher the quality of the resulting crystal and the larger the available area of the wafer.

[0074] The present application is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present application in any way. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in the product instructions shall be followed.

[0075] Example 1

[0076] The crystal growth apparatus in this application is used to grow crystals, specifically as follows:

[0077] A seed crystal with a C-plane angle of 4° in the eccentric direction <11-20> was used and grown at 2050°C for 20 hours. The tilt angle of the crucible in the crystal growth apparatus was adjusted 4° in the opposite direction of the eccentric direction and grown at 2050°C for 230 hours to obtain crystal A.

[0078] Comparative Example 1

[0079] Crystal B was obtained by using a seed crystal with a C-plane angle of 4° in the <11-20> direction and growing at 2050°C for 250h.

[0080] Performance testing

[0081] The crystals were sliced and tested using the Candela device. The results for crystal A are shown in Figure 10 The results of crystal B are shown in Figure 11 , it can be seen that the number of SF defects (blue dots) in crystal A is reduced.

[0082] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0083] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0084] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An angle-adjustable crucible assembly, characterized in that: include: Crucible; The moving component is connected to the crucible and is used to tilt the crucible relative to the vertical direction.

2. The crucible assembly according to claim 1, wherein The mobile component includes: A lug is provided on the outer side wall of the crucible, a transmission shaft connected to the lug; A driving member is connected to the transmission shaft and is used for driving the crucible to tilt relative to a vertical direction via the transmission shaft.

3. The crucible assembly according to claim 2, wherein: The driving member includes: a rotating control column connected to the transmission shaft; The motor is connected to the rotation control column and is used to drive the rotation control column to move up and down.

4. The crucible assembly according to claim 3, wherein: The rotation control column is connected to the transmission shaft by a hinge.

5. The crucible assembly according to claim 3, wherein: Also includes: A tray is located below the crucible with a gap between the tray and the crucible. A through hole is provided on the tray, and the rotation control column is passed through the through hole.

6. The crucible assembly according to claim 5, characterized in that The crucible includes two moving components, and the two moving components are symmetrical about the central axis of the crucible.

7. The crucible assembly according to claim 1, wherein: Also includes: A material barrel is arranged in the crucible and is used to contain crystal growth raw materials. The outer surface of the bottom of the material barrel is a curved surface.

8. The crucible assembly according to claim 7, wherein: Also includes: A plurality of balls are arranged between the crucible and the material barrel.

9. A silicon carbide crystal growth device, characterized in that: The crucible assembly comprises the crucible assembly according to any one of claims 1 to 8.

10. The silicon carbide crystal growth apparatus according to claim 9, wherein: Also includes: The heating barrel is provided with a receiving space inside for receiving the crucible.

11. The silicon carbide crystal growth apparatus according to claim 10, wherein: The moving component passes through the side wall of the heating barrel and is connected to the crucible.

12. A method for growing silicon carbide crystals, characterized in that: include: The θ° off-axis seed crystal is placed in a horizontal direction and grown at 2010°C to 2100°C for 10 hours to 20 hours to obtain a first crystal; Adjusting the angle of the first crystal by -θ° along the horizontal direction and growing the first crystal at 2010° C. to 2100° C. for 200 h to 250 h to obtain the silicon carbide crystal; The horizontal direction is 0°, the side facing the seed crystal polarization direction relative to the horizontal direction is positive, and the side facing the opposite direction of the seed crystal polarization direction relative to the horizontal direction is negative.

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