SiC crystal growth thermal field device and method
By designing a SiC crystal growth thermal field device with a movable first insulation component and a fixed insulation component, the temperature gradient is dynamically adjusted, which solves the problems of polycrystalline, cracks and high basal plane dislocation density in SiC crystal growth and improves the crystal quality.
Patent Information
- Application Number
- CN202510945118.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-10-21
AI Technical Summary
In existing SiC crystal growth technology, the thermal field device cannot dynamically adjust the temperature gradient, resulting in polycrystalline, cracks and phase change defects in the early growth stage, and high basal plane dislocation density in the middle and late stages.
A thermal field device for SiC crystal growth is designed, including a movable first thermal insulation component and a fixed thermal insulation component. By adjusting the position and speed of the first thermal insulation component, the radial and axial temperature gradients are dynamically controlled to achieve continuous surface shape control, avoid edge polycrystals and cracks, and reduce basal plane dislocation density.
It achieves precise dynamic control of the temperature gradient during SiC crystal growth, reduces polycrystalline, cracks and basal plane dislocation density, and improves crystal quality.
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Figure CN120818893A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of SiC crystal growth technology, and specifically relates to a thermal field device and method for SiC crystal growth. Background Art
[0002] In the growth of silicon carbide crystals using the PVT method, the axial temperature gradient is determined by the structure of the hot field crucible, while the radial temperature gradient is mainly adjusted by the top insulation felt. However, in the existing technology, the insulation felt is in a fixed state throughout the growth process or can only be adjusted after the furnace is completed. The existing thermal field design cannot meet the needs of different growth stages: a high convex interface needs to be maintained in the early stage of growth to suppress edge polycrystalline, cracks and phase change defects; in the middle and late stages of growth, a transition to a nearly flat micro-convex interface is required to significantly reduce the basal plane dislocation (BPD) density. Therefore, it is necessary to design a thermal field with continuous surface shape control to dynamically balance defect suppression and crystal quality improvement. Summary of the Invention
[0003] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present application proposes a thermal field device and method that can accurately and dynamically control the temperature gradient at different stages of crystal growth.
[0004] In the first aspect of the present application, a thermal field device for SiC crystal growth is proposed, comprising a fixed thermal insulation component defining a closed thermal insulation space; a crucible disposed in the thermal insulation space, with a movable thermal insulation space between the top of the crucible and the top of the fixed thermal insulation component; and a temperature adjustment component comprising a first thermal insulation member movably disposed within the movable thermal insulation space, the first thermal insulation member being movable along the axial direction of the crucible. This device provides a thermal field device capable of achieving precise and dynamic control of continuous surface shapes, effectively avoiding edge polycrystals, cracks, and initial phase transitions, while effectively reducing the density of basal plane dislocations (BPDs) in the crystal.
[0005] According to an embodiment of the present application, the first thermal insulation component includes a graphite box and thermal insulation felt, wherein the thermal insulation felt is disposed in the graphite box, thereby achieving thermal insulation of the thermal field and regulating the radial temperature gradient.
[0006] According to an embodiment of the present application, the radial dimension of the first heat-insulating member is the same as the radial dimension of the movable heat-insulating space, thereby reducing heat dissipation in the heat field and maintaining the uniformity and stability of the heat field.
[0007] According to an embodiment of the present application, the temperature adjustment assembly further includes an annular second insulation member, which is positioned against the inner sidewall of the fixed insulation assembly and located at the top of the crucible. This second member can thus insulate the edge of the heat field, increasing the edge temperature and making the radial temperature of the heat field more controllable.
[0008] According to an embodiment of the present application, the second thermal insulation component has a positive step structure on the side facing the first thermal insulation component and away from the inner sidewall of the fixed thermal insulation component; the first thermal insulation component has an inverted step structure on the side facing the second thermal insulation component and close to the inner sidewall of the fixed thermal insulation component; and the inverted step structure matches the positive step structure. Thus, the positive step structure of the first thermal insulation component can match the inverted step structure of the second thermal insulation component, allowing precise control of the radial temperature during crystal growth without adding additional load, thereby making the convexity of the crystal growth process more controllable.
[0009] According to an embodiment of the present application, the temperature adjustment assembly further includes a lifting rod, which passes through the top of the fixed heat-insulating assembly and is connected to the first heat-insulating element, thereby enabling controllable lifting and lowering of the first heat-insulating element.
[0010] According to an embodiment of the present application, the temperature adjustment assembly further includes: a rotating shaft connected to the top of the lifting rod for rotating and lifting the lifting rod; and a driving member connected to the rotating shaft for driving the rotating shaft to rotate and lift the lifting rod. Thus, the driving member automates the rotation and lifting operation, thereby improving adjustment efficiency and response speed.
[0011] According to an embodiment of the present application, the thermal field device further includes graphite paper disposed between the crucible and the temperature adjustment assembly. The graphite paper thereby separates the crucible lid from the graphite box, preventing contact between the two, while also collecting polycrystals and preventing crystallization at the bottom of the graphite box.
[0012] According to an embodiment of the present application, the thermal field device further comprises a temperature measuring hole, which passes through the temperature adjustment component, thereby enabling in-situ non-contact temperature measurement.
[0013] A second aspect of the present application provides a method for growing SiC crystals, comprising: continuously moving a first heat-insulating member toward a crucible during the middle and late stages of SiC crystal growth. Consequently, during the middle and late stages of growth, after the first heat-insulating member descends, the thermal field near the bottom of the growth apparatus gradually enhances its heat-insulating effect, causing the temperature of the powder at the center of the thermal field to rise, thereby reducing the axial gradient and resulting in a lower convexity, effectively preventing the problem of a high density of basal plane dislocations (BPDs).
[0014] According to an embodiment of the present application, the growth method further includes: continuously moving the first heat-insulating member toward the crucible during the initial growth phase of the SiC crystal. Thus, by moving the first heat-insulating member during the initial growth phase, the heat-insulating effect on the thermal field is uniform, effectively controlling the convexity of the crystal.
[0015] According to an embodiment of the present application, the growth method further includes: during the initial growth phase of the SiC crystal, the first heat-insulating member is maintained at a distance of 70 mm to 75 mm from the crucible. Thus, during the initial growth phase, the heat-insulating effect is weakened, resulting in a larger crystal convexity and reduced polycrystallinity and cracking.
[0016] According to an embodiment of the present application, the growth method further includes: during the initial growth phase of the SiC crystal, the first heat-insulating member remains stationary at a distance of 30 mm to 45 mm from the crucible. This allows for more controllable descent distance and speed of the first heat-insulating member, thereby reducing thermal field disturbances.
[0017] According to an embodiment of the present application, the movement speed of the first heat-insulating member is 0.05 mm / h-1000 mm / h. Thus, within the above movement speed range, the thermal field adjustment can be smoother and gradient fluctuations can be reduced.
[0018] This application has at least the following beneficial effects:
[0019] 1) The relative position of the thermal field as a whole and the coil is fixed, avoiding the large fluctuations caused by the traditional method of maintaining or controlling the temperature gradient by moving the coil;
[0020] 2) Realize segmented / continuous surface control during crystal growth, and accurately and dynamically control the temperature gradient at different stages of crystal growth;
[0021] 3) The adjustment of the process can be directly reflected by the "convexity" of the surface shape. The optimal test parameters can be determined by using the correspondence between the surface shape and defects after crystal growth in different time periods. The process can be replicated and stably promoted. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a schematic diagram of the growth surface of the SiC crystal in the early, middle and late stages of growth in this application.
[0023] Figure 2 This is a schematic diagram of a SiC crystal growth thermal field device according to an embodiment of the present application.
[0024] Figure 3 This is a schematic diagram of a SiC crystal growth thermal field device according to another embodiment of the present application.
[0025] Figure 4 This is a schematic diagram of a SiC crystal growth thermal field device according to an embodiment of the present application.
[0026] Reference numerals:
[0027] 10-insulation assembly; 11-insulation space; 20-crucible; 21-crucible body; 22-crucible cover; 30-first insulation component; 31-graphite box; 32-insulation felt; 40-lifting rod; 50-temperature measuring hole; 60-graphite paper; 70-powder; 80-second insulation component; 90-rotating shaft; 100-driving component. DETAILED DESCRIPTION
[0028] The embodiments of the present application are described in detail below, which are intended to explain the present invention but are not to be construed as limiting the present invention.
[0029] Understandable, refer to Figure 1 During the SiC crystal growth process, the SiC crystal growth process can be divided into different stages, and the radial temperature gradient can be adjusted according to the requirements for the growth surface shape in different stages. Ideally, in the early stages of SiC crystal growth, a relatively convex growth surface shape must be maintained. That is, the radial temperature gradient required for growth is small. This can prevent polycrystalline from invading the single crystal area and effectively avoid crystal defects such as edge polycrystalline, cracks, and early phase transformations that seriously affect crystal quality. In the middle and late stages of crystal growth, the surface shape should be controlled and the convexity should be continuously reduced to obtain a "nearly flat and slightly convex" state. This can effectively reduce the density of basal plane dislocations (BPDs) in the crystal.
[0030] In this article, growth face type refers to the external geometric characteristics of a crystal naturally formed under free growth conditions, which reflects the growth degree of different crystal faces during the growth process.
[0031] In this article, basal plane dislocations (BPDs) are dislocations along the basal planes of a crystal, formed due to imperfect atomic arrangement. Basal plane dislocation density refers to the total length of basal plane dislocations per unit volume or area. This can be measured statistically on specific crystal planes using chemical etching pits, X-ray topographies (XRT), or transmission electron microscopy (TEM).
[0032] In the first aspect of the present application, a SiC crystal growth thermal field device is proposed, referring to Figure 2The thermal field device includes a fixed thermal insulation assembly 10 defining a closed thermal insulation space; a crucible 20 disposed in the thermal insulation space, with a movable thermal insulation space 11 defined between the top of the crucible 20 and the top of the fixed thermal insulation assembly 10; and a temperature adjustment assembly including a first thermal insulation member 30 movably disposed within the movable thermal insulation space 11. The first thermal insulation member 30 is movable along the axial direction of the crucible 20. The device can adjust the radial temperature gradient of the SiC crystal growth thermal field by moving the position of the first thermal insulation member during SiC crystal growth. The SiC crystal growth thermal field is controlled to have an appropriate radial temperature gradient at different stages of crystal growth, thereby achieving an initially convex growth surface shape of the SiC crystal, with the convexity gradually decreasing and ultimately achieving a nearly flat and slightly convex state, thereby obtaining a high-quality SiC crystal. In other words, the device can achieve precise and dynamic control of the thermal field of a continuous surface shape, effectively avoiding edge polycrystallinity, cracks, and initial phase transitions, while effectively reducing the density of basal plane dislocations (BPDs) in the crystal.
[0033] According to the embodiments of this application, referring to Figure 2 , the first thermal insulation component 30 includes: a graphite box 31; an insulation felt 32, and the insulation felt 32 is arranged in the graphite box 31. Therefore, the graphite box as a container can constrain the insulation felt to prevent heat leakage, and can isolate the external cold air flow to maintain the edge temperature stability. On the one hand, the role of the insulation felt is to reduce heat loss and ensure the temperature stability of the crystal growth area. By wrapping it inside the graphite box, the insulation felt can form a good insulation layer to reduce the impact of external temperature fluctuations on crystal growth; on the other hand, the insulation felt has good thermal insulation properties and can effectively isolate external heat to ensure that the temperature of the crystal growth area is controlled within an appropriate range.
[0034] According to an embodiment of the present application, the radial dimension of the first heat-insulating member is the same as the radial dimension of the movable heat-insulating space, thereby reducing heat dissipation in the heat field and maintaining the uniformity and stability of the heat field.
[0035] It should be noted that the first heat-insulating component 30 can be placed exactly in the movable heat-insulating space, and a certain error fluctuation range is allowed.
[0036] According to the embodiments of this application, referring to Figure 3 The temperature adjustment assembly further includes an annular second insulation member 80, which is attached to the inner sidewall of the fixed insulation assembly 10 and located on top of the crucible 20. Thus, the second member 80 can insulate the edge of the heat field, thereby increasing the edge temperature of the heat field, suppressing edge heat dissipation, and making the radial temperature of the heat field more controllable.
[0037] According to the embodiments of this application, referring to Figure 3, the second thermal insulation part 80 has a positive step structure on the side away from the inner wall of the fixed thermal insulation component 10 and facing the first thermal insulation part 30; the first thermal insulation part 30 has an inverted step structure on the side close to the inner wall of the fixed thermal insulation component 10 and facing the second thermal insulation part 80; the inverted step structure matches the positive step structure. Thus, the stepped structure enables the second thermal insulation part to have a longer thermal resistance channel, realizes the gradient distribution of thermal resistance, can suppress the airflow in a specific direction, and accurately control the edge temperature. During the crystal growth process, by moving the first thermal insulation part 30 so that its positive step structure is inserted into the inverted step of the second thermal insulation part 80, the heat loss at the edge of the thermal field can be reduced, and the edge temperature can be increased without adding additional load, thereby making the convexity during the crystal growth process more controllable.
[0038] In this article, the convexity is calculated by taking the highest point of the crystal center thickness, using a thickness gauge with an accuracy of 0.001mm to obtain data, and then taking the 6 points at the edge of the crystal in a cross-shaped pattern, taking the average of the 6 points, and the convexity is calculated by subtracting the average of the 6 points at the edge from the center thickness. The ideal control range of the final convexity is 0.5-1.
[0039] According to the embodiments of this application, referring to Figure 2 The temperature adjustment assembly further includes a lifting rod 40, which passes through the top of the fixed heat-insulating assembly 10 and is connected to the first heat-insulating element. Thus, the first heat-insulating element can be raised and lowered in a controlled manner.
[0040] According to the embodiments of this application, referring to Figure 4 The temperature adjustment assembly further includes a rotating shaft 90 connected to the top of the lifting rod 40 for rotating and lifting the lifting rod 40; and a driving member 100 connected to the rotating shaft 90 for driving the rotating shaft 90 to rotate and lift. The driving member 100 automates the rotation and lifting operations, thereby improving adjustment efficiency and response speed.
[0041] According to the embodiments of this application, referring to Figure 1 The thermal field device further includes graphite paper 60, which is disposed between the crucible 20 and the temperature adjustment assembly. The graphite paper 60 can separate the crucible cover from the graphite box to prevent contact between the two, while collecting polycrystals and preventing crystallization at the bottom of the graphite box.
[0042] According to an embodiment of the present application, the thermal field device further includes a temperature measuring hole 50, which passes through the temperature adjustment component, thereby enabling in-situ non-contact temperature measurement.
[0043] In this paper, the crystal growth process is 200 hours in total. The early stage of crystal growth refers to the 45th to 50th hour after the crystal enters the growth stage, and the middle and late stages of crystal growth refer to the 150th to 155th hour after the crystal enters the growth stage 45th to 50th hour to the end of 200 hours.
[0044] According to an embodiment of the present application, the fixed insulation component 10 includes a hard insulation felt outside the thermal field, which, on the one hand, suppresses the transfer of internal temperature to the furnace wall and reduces system energy consumption; on the other hand, it can reduce longitudinal heat loss, maintain a high temperature environment of the thermal field, and reduce temperature fluctuations.
[0045] According to an embodiment of the present application, the crucible 20 includes a crucible body 21 and a crucible cover 22, which serves as a container for crystal growth, is used to hold raw materials and form a melt at high temperature, transfer the heat generated by the induction coil to the melt, and ensure that the heat is efficiently converted into a driving force for crystal growth.
[0046] A second aspect of the present application provides a method for growing SiC crystals, comprising: continuously moving a first heat-insulating member toward a crucible during the middle and late stages of SiC crystal growth. Consequently, after the first heat-insulating member descends during the middle and late stages of growth, the thermal field near the bottom of the growth apparatus gradually enhances the heat-insulating effect, causing the temperature at the center of the powder 70 to rise, thereby reducing the axial gradient and resulting in a lower convexity, effectively preventing the problem of a high density of basal plane dislocations (BPDs).
[0047] It is understandable that during the initial stages of crystal growth, when the first heat-insulating element is positioned away from the crucible, its insulation effect is weak. Maintaining a constant temperature at the top of the heat field increases the load applied by the entire heat field, causing the temperature of the powder 70 at the center of the heat field to be significantly higher than that at the center of the seed crystal, thereby increasing the axial gradient. Furthermore, heating by the induction coil raises the temperature at the edges of the heat field. At this point, the temperature of the powder 70 at the center of the heat field is lower than that at the center of the seed crystal, increasing the axial gradient at the center. This, in turn, increases the crystal convexity and reduces polycrystalline formation, cracking, and phase transition issues during the initial stages of crystal growth.
[0048] According to an embodiment of the present application, the growth method further includes: continuously moving the first heat-insulating member toward the crucible during the initial growth phase of the SiC crystal. Thus, by moving the first heat-insulating member during the initial growth phase, the heat-insulating effect on the thermal field is uniform, effectively controlling the convexity of the crystal.
[0049] According to an embodiment of the present application, the growth method further includes: during the initial growth phase of the SiC crystal, the first heat-insulating member is maintained stationary at a distance of 70 mm to 75 mm from the crucible, with the distances between the first heat-insulating member and the crucible being specifically 70 mm, 71 mm, 72 mm, 73 mm, 74 mm, and 75 mm. Thus, during the initial growth phase, the heat-insulating effect is weakened, resulting in a greater convexity of the crystal and reduced polycrystallinity and cracking.
[0050] According to an embodiment of the present application, the growth method further includes: in the early stages of SiC crystal growth, the first thermal insulation member remains stationary at a distance of 30 mm to 45 mm from the crucible, with the distances between the first thermal insulation member and the crucible being specifically 30 mm, 33 mm, 36 mm, 39 mm, 42 mm, and 45 mm. This allows for more controllable descent distance and speed of the first thermal insulation member, reducing thermal field disturbances.
[0051] According to an embodiment of the present application, the movement speed of the first thermal insulation member is 0.05 mm / h-1000 mm / h, for example, 0.05 mm / h, 0.1 mm / h, 0.2 mm / h, 0.5 mm / h, 1 mm / h, 10 mm / h, 50 mm / h, 100 mm / h, 200 mm / h, 300 mm / h, 400 mm / h, 500 mm / h, 600 mm / h, 700 mm / h, 800 mm / h, 900 mm / h, and 1000 mm / h. Thus, within the above movement speed range, the thermal field adjustment can be smoother and gradient fluctuations can be reduced.
[0052] The embodiments of the present application are described in detail below.
[0053] Example 1 and Example 2 utilize Figure 1 The device shown is used to grow SiC crystals. The specific growth method is as follows:
[0054] Example 1
[0055] 1) Mechanical pump and turbomolecular pump vacuum acquisition for 2 hours; process leak detection for 30 minutes;
[0056] 2) The pressure was increased to 80,000 Pa (Ar flow rate 1,000 sccm) within 30 min, and the power was 0;
[0057] 3) The pressure was maintained at 80,000 Pa (Ar flow rate was reduced to 50 sccm) for 10 minutes, and the power was 0;
[0058] 4) The pressure dropped to 10,000 Pa (Ar flow rate dropped to 50 sccm) within 30 minutes, and the power was 2 kW;
[0059] 5) The pressure was maintained at 10,000 Pa (Ar flow rate was maintained at 50 sccm) and the power was 14.5 kW for 3 h;
[0060] 6) The pressure was reduced to 5000 Pa within 10 min (Ar flow rate was maintained at 50 sccm, N2 flow rate was 3 sccm), and the power was 14.5 kW; temperature control was switched from step 5) and the temperature on the back of the crucible lid was controlled to 2050°C;
[0061] 7) The pressure was reduced to 200 Pa within 7 h (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm), and the temperature was controlled at 2050°C;
[0062] 8) The pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was maintained at 3 sccm) for 50 h, and the temperature was controlled at 2050° C. After the transition from step 7) to step 8), the graphite box was moved downward at a speed of 0.5 mm / h, with a downward movement of 25 mm within 50 h;
[0063] 9) After step 8), the pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, and nitrogen flow rate was 3 sccm) for the remaining 150 h, the temperature was controlled at 2050° C., and the graphite box was still moved down at a speed of 0.5 mm / h until the crystal growth was completed;
[0064] 10) Pressure increased by 5000 Pa in 30 minutes (Ar flow rate 1000 sccm, nitrogen flow rate 0 sccm), power 5 kW;
[0065] 11) The pressure rises by 50,000 Pa in 1 h (Ar flow rate 1,000 sccm, nitrogen flow rate 0 sccm), and the power is 0 kW;
[0066] 12) Cool for 48 hours and open the furnace.
[0067] Example 2
[0068] 1) Mechanical pump and turbomolecular pump vacuum acquisition for 2 hours; process leak detection for 30 minutes;
[0069] 2) The pressure was increased to 80,000 Pa (Ar flow rate 1,000 sccm) within 30 min, and the power was 0;
[0070] 3) The pressure was maintained at 80,000 Pa (Ar flow rate was reduced to 50 sccm) for 10 minutes, the power was set to 0, and the graphite box was rapidly lowered to 75 mm from the back of the crucible cover within 1 minute;
[0071] 4) The pressure dropped to 10,000 Pa (Ar flow rate dropped to 50 sccm) within 30 minutes, and the power was 2 kW;
[0072] 5) The pressure was maintained at 10,000 Pa (Ar flow rate was maintained at 50 sccm) and the power was 14.5 kW for 3 h;
[0073] 6) The pressure was reduced to 5000 Pa within 10 min (Ar flow rate was maintained at 50 sccm, N2 flow rate was 3 sccm), and the power was 14.5 kW; temperature control was switched from step 5) and the temperature on the back of the crucible lid was controlled to 2050°C;
[0074] 7) The pressure was reduced to 200 Pa within 7 h (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm), and the temperature was controlled at 2050°C;
[0075] 8) The pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm) for 50 h, the temperature was controlled at 2050 ° C, and the graphite box was not moved before the end of 50 h;
[0076] 9) After step 8), the pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, and nitrogen flow rate was 3 sccm) for the remaining 150 h, the temperature was controlled at 2050° C., and the graphite box was moved down at a speed of 0.5 mm / h until the crystal growth was completed;
[0077] 10) Pressure increased by 5000 Pa in 30 minutes (Ar flow rate 1000 sccm, nitrogen flow rate 0 sccm), power 5 kW;
[0078] 11) The pressure rises by 50,000 Pa in 1 h (Ar flow rate 1,000 sccm, nitrogen flow rate 0 sccm), and the power is 0 kW;
[0079] 12) Cool for 48 hours and open the furnace.
[0080] Example 3 and Example 4 utilize Figure 2 The device shown is used to grow SiC crystals. The specific growth method is as follows:
[0081] Example 3
[0082] 1) Mechanical pump and turbomolecular pump vacuum acquisition for 2 hours; process leak detection for 30 minutes;
[0083] 2) The pressure was increased to 80,000 Pa (Ar flow rate 1,000 sccm) within 30 min, and the power was 0;
[0084] 3) The pressure was maintained at 80,000 Pa (Ar flow rate was reduced to 50 sccm) for 10 minutes, and the power was 0;
[0085] 4) The pressure dropped to 10,000 Pa (Ar flow rate dropped to 50 sccm) within 30 minutes, and the power was 2 kW;
[0086] 5) The pressure was maintained at 10,000 Pa (Ar flow rate was maintained at 50 sccm) and the power was 14.5 kW for 3 h;
[0087] 6) The pressure was reduced to 5000 Pa within 10 min (Ar flow rate was maintained at 50 sccm, N2 flow rate was 3 sccm), and the power was 14.5 kW; temperature control was switched from step 5) and the temperature on the back of the crucible lid was controlled to 2050°C;
[0088] 7) The pressure was reduced to 200 Pa within 7 h (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm), and the temperature was controlled at 2050°C;
[0089] 8) The pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, and nitrogen flow rate was maintained at 3 sccm) for 50 h, and the temperature was controlled at 2050° C. After step 7) was switched to step 8), the graphite box was moved downward at a speed of 0.2 mm / h, and the downward movement was 10 mm within 50 h;
[0090] 9) After step 8), the pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, and nitrogen flow rate was 3 sccm) for the remaining 150 h, the temperature was controlled at 2050° C., and the graphite box was still moved downward at a speed of 0.2 mm / h until the crystal growth was completed;
[0091] 10) Pressure increased by 5000 Pa in 30 minutes (Ar flow rate 1000 sccm, nitrogen flow rate 0 sccm), power 5 kW;
[0092] 11) The pressure rises by 50,000 Pa in 1 h (Ar flow rate 1,000 sccm, nitrogen flow rate 0 sccm), and the power is 0 kW;
[0093] 12) Cool for 48 hours and open the furnace.
[0094] Example 4
[0095] 1) Mechanical pump and turbomolecular pump vacuum acquisition for 2 hours; process leak detection for 30 minutes;
[0096] 2) The pressure was increased to 80,000 Pa (Ar flow rate 1,000 sccm) within 30 min, and the power was 0;
[0097] 3) The pressure was maintained at 80,000 Pa (Ar flow rate was reduced to 50 sccm) for 10 minutes, the power was set to 0, and the graphite box was rapidly lowered to 30 mm from the back of the crucible cover within 1 minute;
[0098] 4) The pressure dropped to 10,000 Pa (Ar flow rate dropped to 50 sccm) within 30 minutes, and the power was 2 kW;
[0099] 5) The pressure was maintained at 10,000 Pa (Ar flow rate was maintained at 50 sccm) and the power was 14.5 kW for 3 h;
[0100] 6) The pressure was reduced to 5000 Pa within 10 min (Ar flow rate was maintained at 50 sccm, N2 flow rate was 3 sccm), and the power was 14.5 kW; temperature control was switched from step 5) and the temperature on the back of the crucible lid was controlled to 2050°C;
[0101] 7) The pressure was reduced to 200 Pa within 7 h (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm), and the temperature was controlled at 2050°C;
[0102] 8) The pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm) for 50 h, the temperature was controlled at 2050 ° C, and the graphite box was not moved before the end of 50 h;
[0103] 9) After step 8), the pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, and nitrogen flow rate was 3 sccm) for the remaining 150 h, the temperature was controlled at 2050° C., and the graphite box was moved down at a speed of 0.2 mm / h until the crystal growth was completed;
[0104] 10) Pressure increased by 5000 Pa in 30 minutes (Ar flow rate 1000 sccm, nitrogen flow rate 0 sccm), power 5 kW;
[0105] 11) The pressure rises by 50,000 Pa in 1 h (Ar flow rate 1,000 sccm, nitrogen flow rate 0 sccm), and the power is 0 kW;
[0106] 12) Cool for 48 hours and open the furnace.
[0107] Comparative Example 1
[0108] 1) Mechanical pump and turbomolecular pump vacuum acquisition for 2 hours; process leak detection for 30 minutes;
[0109] 2) The pressure was increased to 80,000 Pa (Ar flow rate 1,000 sccm) within 30 min, and the power was 0;
[0110] 3) The pressure is maintained at 80,000 Pa (Ar flow rate is reduced to 50 sccm) for 10 minutes, and the power is 0. At this time, the graphite box is at the top of the insulation space. In the following steps, the graphite box remains stationary until the crystal growth is completed.
[0111] 4) The pressure dropped to 10,000 Pa (Ar flow rate dropped to 50 sccm) within 30 minutes, and the power was 2 kW;
[0112] 5) The pressure was maintained at 10,000 Pa (Ar flow rate was maintained at 50 sccm) and the power was 14.5 kW for 3 h;
[0113] 6) The pressure was reduced to 5000 Pa within 10 min (Ar flow rate was maintained at 50 sccm, N2 flow rate was 3 sccm), and the power was 14.5 kW; temperature control was switched from step 5) and the temperature on the back of the crucible lid was controlled to 2050°C;
[0114] 7) The pressure was reduced to 200 Pa within 7 h (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was 3 sccm), and the temperature was controlled at 2050°C;
[0115] 8) The pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was maintained at 3 sccm) for 50 h, and the temperature was controlled at 2050°C;
[0116] 9) After step 8), the pressure was maintained at 200 Pa (Ar flow rate was maintained at 50 sccm, nitrogen flow rate was maintained at 3 sccm), and the temperature was controlled at 2050°C for the remaining 150 h;
[0117] 10) Pressure increased by 5000 Pa in 30 minutes (Ar flow rate 1000 sccm, nitrogen flow rate 0 sccm), power 5 kW;
[0118] 11) The pressure rises by 50,000 Pa in 1 h (Ar flow rate 1,000 sccm, nitrogen flow rate 0 sccm), and the power is 0 kW;
[0119] 12) Cool for 48 hours and open the furnace.
[0120] SiC crystal growth parameter test method:
[0121] Polycrystalline at the facet: Polycrystalline can be seen by visual inspection of SiC crystals.
[0122] Crack length at the small face: measured with a vernier caliper.
[0123] Number of cracks on the small face: The number of cracks can be seen by visual inspection of the SiC crystal.
[0124] Growth convexity: Take the highest point of the crystal center thickness, use a thickness gauge with an accuracy of 0.001mm to obtain data, then take 6 points at the edge of the crystal in a M-shaped pattern, take the average of the 6 points, and subtract the average of the 6 edge points from the center thickness.
[0125] Basal plane dislocation density: After etching with molten KOH at 450℃ for 15 minutes, the dislocation density was identified and captured using a dislocation meter.
[0126] Table 1
[0127]
[0128] *Facet is a flat area formed by differences in growth rates of a specific crystal plane.
[0129] It can be seen from Table 1 that the use of the SiC crystal growth apparatus of the present application can effectively avoid edge polycrystals and cracks, while effectively reducing the density of basal plane dislocations (BPDs) of the crystal.
[0130] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.
[0131] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.
[0132] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.
[0133] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean 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 invention. 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.
[0134] Although the embodiments of the present application have been shown and described above, it will be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.
Claims
1. A SiC crystal growth thermal field device, characterized in that: include: A fixed heat-insulating assembly defining a closed heat-insulating space; A crucible is disposed in the heat-insulating space, with a movable heat-insulating space being provided between the top of the crucible and the top of the fixed heat-insulating assembly; The temperature regulating component includes a first heat-insulating component, which is movably arranged in the movable heat-insulating space and can move along the axial direction of the crucible.
2. The thermal field device according to claim 1, characterized in that: The first thermal insulation component comprises: Graphite box; Thermal insulation felt is arranged in the graphite box.
3. The thermal field device according to claim 1, characterized in that: The radial dimension of the first heat-insulating component is the same as the radial dimension of the movable heat-insulating space.
4. The thermal field device according to claim 1, characterized in that: The temperature regulating component further includes a second annular heat-insulating component, which is arranged in contact with the inner side wall of the fixed heat-insulating component and is located on the top of the crucible.
5. The thermal field device according to claim 4, characterized in that: The second heat-insulating component has a positive step structure on a side away from the inner side wall of the fixed heat-insulating component and facing the first heat-insulating component; The first heat-insulating component has an inverted step structure on a side close to the inner side wall of the fixed heat-insulating component and facing the second heat-insulating component; The inverted step structure matches the positive step structure.
6. The thermal field device according to any one of claims 1 to 5, characterized in that: The temperature regulating assembly further comprises: A lifting rod is provided, wherein the lifting rod passes through the top of the fixed heat-insulating component and is connected to the first heat-insulating component.
7. The thermal field device according to claim 6, characterized in that: The temperature regulating assembly further comprises: A rotating shaft connected to the top of the lifting rod, used for rotating and lifting the lifting rod; A driving member is connected to the rotating shaft and is used to drive the rotating shaft to rotate and pull.
8. The thermal field device according to claim 1, characterized in that: Also includes: Graphite paper is arranged between the crucible and the temperature regulating component.
9. The thermal field device according to claim 1, characterized in that: It also includes a temperature measuring hole, which passes through the temperature regulating component.
10. A method for growing SiC crystal using the thermal field device according to any one of claims 1 to 9, characterized in that: include: In the middle and late stages of SiC crystal growth, the first heat retaining member is continuously moved toward the crucible.
11. The method according to claim 10, characterized in that Also includes any of the following: In the early stage of SiC crystal growth, the first heat-insulating member is continuously moved toward the crucible; In the early stage of SiC crystal growth, the first heat-insulating member remains stationary at a distance of 70 mm to 75 mm from the crucible; In the early stage of SiC crystal growth, the first heat-insulating member remains stationary at a position 30 mm to 45 mm away from the crucible.
12. The method according to claim 10, characterized in that The moving speed of the first heat-insulating component is 0.05 mm / h-1000 mm / h.