Temperature field regulation and control device and single crystal furnace

Abstract

The embodiment of the invention provides a temperature field regulation and control device and a single crystal furnace, the device comprises a crucible, an inner reflecting screen and an auxiliary side reflecting screen, the crucible is at least partially located in a heater and comprises a crucible body and a crucible cover covering the crucible body, the interior of the crucible cover is used for arranging seed crystals, the crucible body comprises an upper section, a middle section and a lower section, and the upper section is located in the middle section; the middle section comprises a middle part and an annular part, the inner diameter of the middle part is consistent with that of the upper section and the lower section, the diameter of the annular part is larger than that of the upper section and the lower section, and the middle part and the lower section are used for containing raw materials; the inner reflecting screen is arranged in the annular part and used for reflecting heat in the direction away from the crucible body. The auxiliary side reflecting screen is arranged outside the crucible and is supported on the middle section, and the top end of the auxiliary side reflecting screen is higher than the top end of the crucible cover. The temperature field regulation and control device can increase the temperature gradient between the upper section and the lower section of the crucible, so that the requirements of crystal growth are met, and the crystal growth quality is improved.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum nitride single crystals, and in particular to a single temperature field control device and a single crystal furnace. Background Art

[0002] The third generation semiconductor aluminum nitride single crystal material has an irreplaceable and important role in the fields of deep ultraviolet optoelectronics, high power density electronic devices, and radio frequency devices due to its excellent performance such as large bandgap width of 6.2eV, high breakdown field strength of 11.7MV / cm, and high thermal conductivity of 3.4W / cm·K. In addition, its lattice mismatch rate with GaN is 2.4%, and its thermal expansion coefficient is basically close, making it an ideal substrate material for preparing GaN-related devices.

[0003] At present, the main method for synthesizing AlN single crystals in the industry is physical vapor transport (PVT). Physical vapor transport is a process in which raw materials sublimate in a high temperature zone, a suitable temperature difference is formed between the raw material zone and the seed crystal zone, and deposition and growth are carried out in the seed crystal zone. Therefore, the temperature field design and regulation of AlN single crystal growth are very important. Different stages of the AlN single crystal growth process require different temperature gradients. During the heating process, in order to remove the contamination on the surface of the seed crystal, an inverse temperature gradient is usually used to heat up. After reaching the temperature, the number of nuclei on the surface of the seed crystal needs to be controlled in the early stage of growth, and the temperature gradient should not be too large. In the middle and late stages of crystal growth, as the crystal grows, the temperature gradient needs to be increased to maintain the crystal surface temperature and gas saturation. In order to obtain an actual and effective temperature gradient, a single temperature zone, a double temperature zone, or even a multi-temperature zone resistance furnace design is adopted. The design of the double temperature zone and multi-temperature zone furnace is relatively complex, the control stability is poor, the furnace maintenance is inconvenient, and the maintenance cost is high. The single temperature zone furnace design is relatively simple, the temperature field stability is good, but it is difficult to achieve a large temperature gradient, so defects are prone to occur during the crystal growth process, resulting in poor crystal quality. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a temperature field control device and a single crystal furnace to solve the problem that a single temperature zone furnace is difficult to achieve a large stable gradient. The specific technical solution is as follows:

[0005] The first aspect of the present application provides a temperature field control device, comprising: a crucible, at least partially located inside a heater, comprising a crucible body and a crucible cover covering the crucible body, the interior of the crucible cover being used to set a seed crystal, the crucible body comprising an upper section, a middle section and a lower section, the inner diameter of the middle section being larger than that of the upper section and the lower section, the middle section comprising a middle section consistent with the inner diameter of the upper section and the lower section and an annular section having a diameter larger than that of the upper section and the lower section, the middle section and the lower section being used to accommodate raw materials; an internal reflection screen, disposed in the annular section, for reflecting heat away from the crucible body; an auxiliary side reflection screen, disposed outside the crucible and supported on the middle section, the top end of the auxiliary side reflection screen being higher than the top end of the crucible cover.

[0006] In some embodiments, the temperature field control device further includes an auxiliary upper reflection screen disposed above the crucible cover, the auxiliary upper reflection screen has a first opening in the middle, and the first opening is coaxially disposed with the seed crystal.

[0007] In some embodiments, the size of the first opening is equal to the diameter of the seed crystal; or, the first opening is a gradual opening, and the maximum size of the first opening is equal to the diameter of the seed crystal, and the minimum size is greater than or equal to 1 / 2 of the diameter of the seed crystal.

[0008] In some embodiments, the auxiliary side reflection screen includes at least one first reflection layer. When it includes two or more first reflection layers, a first support member is arranged between adjacent first reflection layers to separate the first reflection layers; the auxiliary upper reflection screen includes at least one second reflection layer. When it includes two or more second reflection layers, a second support member is arranged between adjacent second reflection layers to separate the second reflection layers.

[0009] In some embodiments, the auxiliary side reflection screen includes five first reflection layers, the outermost and second outermost first reflection layers are supported on the middle section, the bottoms of the remaining three first reflection layers are not in contact with the middle section, and the distance between each first reflection layer and the middle section increases successively in the direction approaching the side wall of the crucible.

[0010] In some embodiments, a groove is provided on the outer side of the crucible cover corresponding to the position where the seed crystal is set, and the diameter of the groove is less than or equal to 1 / 2 of the diameter of the seed crystal.

[0011] In some embodiments, the depth of the groove is less than or equal to 1 / 2 of the thickness of the crucible cover.

[0012] In some embodiments, the temperature field control device includes a baffle, which is arranged inside the crucible and located at the bottom end of the upper section. The baffle includes a hollow area and a shielding area arranged around the hollow area, and the range of the hollow area is consistent with the size of the seed crystal.

[0013] In some embodiments, a boss is provided at the bottom end of the inner wall of the upper section, and the baffle is supported on the boss.

[0014] In some embodiments, the hollow area includes one through hole; or, the hollow area includes a plurality of through holes that are evenly arranged.

[0015] In some embodiments, the temperature field control device also includes: a lower reflection screen, located below the heater and the crucible, the lower reflection screen including a through hole; a side reflection screen, the side reflection screen is cylindrical, and the side reflection screen is sleeved on the outer periphery of the lower reflection screen; an upper reflection screen, the upper reflection screen covers the side reflection screen or is inscribed in the side reflection screen, so that the lower reflection screen, the side reflection screen and the upper reflection screen form a hollow cavity, the crucible, the auxiliary side reflection screen and the auxiliary upper reflection screen are located in the cavity, the upper reflection screen has a second opening opposite to the first opening along the height direction, and the opening area of ​​the second opening gradually decreases in the direction away from the crucible cover.

[0016] In some embodiments, the first reflective layer and the second reflective layer are both tungsten plates; the first support member and the second support member are both U-shaped pure tungsten members.

[0017] A second aspect of the present application provides a single crystal furnace, the single crystal furnace comprising: a furnace body, the inner wall of which is provided with electrodes; a furnace cover, which covers the furnace body;

[0018] The heater is arranged inside the furnace body, and the two or three electrodes of the heater are connected to the electrodes; the temperature field control device mentioned above is placed inside the furnace body.

[0019] Beneficial effects of the embodiments of the present application:

[0020] The temperature field control device and the single crystal furnace provided by the embodiment of the present application include a crucible, an internal reflection screen and an auxiliary side reflection screen. The internal reflection screen is arranged inside the crucible and located in the middle section of the crucible. The auxiliary side reflection screen is supported on the middle section of the crucible to shield the middle section and the upper section of the crucible and block the heat entering the middle section and the upper section of the crucible. When the crucible is completely inside the heater, the internal reflection screen and the auxiliary side reflection screen can increase the temperature gradient between the lower section and the upper section of the crucible, and the temperature of the lower section is greater than the temperature of the upper section, so as to achieve the purpose of increasing the temperature gradient between the upper section and the lower section, which is conducive to forming an effective temperature gradient between the high temperature zone of the raw material and the low temperature zone of the seed crystal, and by adjusting the number of the internal reflection screen, the auxiliary side reflection screen and the auxiliary upper reflection screen, the effective temperature gradient difference can be adjusted between 35°C and 200°C, which expands the temperature gradient between the upper section and the lower section of the crucible, and can adjust the temperature gradient suitable for crystal growth, thereby improving the quality of the crystal. In addition, the internal reflection screen and the auxiliary side reflection screen can reduce the sublimation rate of the side wall raw materials, and the lower part is directly heated, which is conducive to the first sublimation of the bottom of the raw materials and improves the utilization rate of the raw materials.

[0021] Of course, implementing any product or method of the present application does not necessarily require achieving all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0023] Figure 1 A schematic diagram of the structure of a temperature field control device provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of the structure of a crucible provided in an embodiment of the present application in one embodiment;

[0025] Figure 3 for Figure 2 a middle crucible, wherein the annular portion has an internal reflection screen placed therein;

[0026] Figure 4 A partial cross-sectional schematic diagram of the auxiliary side reflective screen provided in an embodiment of the present application;

[0027] Figure 5 A schematic diagram of the structure of the temperature field control device provided in an embodiment of the present application in another embodiment;

[0028] Figure 6 A schematic diagram of the structure of a baffle provided in an embodiment of the present application in one embodiment;

[0029] Figure 7 A schematic diagram of the structure of the baffle provided in an embodiment of the present application in another embodiment;

[0030] Figure 8 A schematic diagram of the structure of a single crystal furnace in one embodiment of the present application.

[0031] The reference numerals are as follows:

[0032] Crucible 1; crucible body 11; upper section 111; boss 1111; middle section 112; annular portion 1121; middle portion 1122; lower section 113; crucible cover 12; groove 121; tungsten rod 13; internal reflection screen 2; auxiliary side reflection screen 3; first reflection layer 31; first support member 32; auxiliary upper reflection screen 4; first opening 41; second reflection layer 42; baffle 5; hollow area 51; through hole 511; shielding area 52; upper reflection screen 6; third reflection layer 61; second opening 62; lower reflection screen 7; fourth reflection layer 71; through hole 72; side reflection screen 8; fifth reflection layer 81; heater 9; furnace body S1; furnace cover S2; seed crystal M; raw material N. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field based on the present application belong to the scope of protection of the present application.

[0034] The first aspect of the present application provides a temperature field control device, such as Figure 1 As shown, the crucible 1 includes a crucible 1, an internal reflection screen 2 and an auxiliary side reflection screen 3. The crucible 1 is at least partially located inside the heater 9, and includes a crucible body 11 and a crucible cover 12 covering the crucible body 11. The crucible cover 12 is used to set a seed crystal M inside. Figure 2 , Figure 3 As shown, the crucible body 11 includes an upper section 111, a middle section 112 and a lower section 113. The inner diameter of the middle section 112 is larger than that of the upper section 111 and the lower section 113. The middle section 112 includes a middle portion 1122 having the same inner diameter as that of the upper section 111 and the lower section 113 and an annular portion 1121 having a diameter larger than that of the upper section 111 and the lower section 113. The middle portion 1122 and the lower section 113 are used to accommodate the raw material N. The internal reflection screen 2 is disposed in the annular portion 1121 to reflect heat away from the crucible body 11. The auxiliary side reflection screen 3 is disposed outside the crucible 1 and supported on the middle section 112. The top of the auxiliary side reflection screen 3 is higher than the top of the crucible cover 12.

[0035] like Figure 2 , Figure 3As shown, the middle part 1122 of the crucible 1 and the part below it are used to hold the raw material N, the inner reflection screen 2 is arranged in the annular part 1121 of the middle section 112 of the crucible 1, and the auxiliary side reflection screen 3 supported on the middle section 112 is arranged outside the crucible 1, and the inner reflection screen 2 and the auxiliary side reflection screen 3 can block the heat entering the middle section 112 and the upper section 111 of the crucible 1. When the crucible 1 is completely located inside the heater 9, the inner reflection screen 2 and the auxiliary side reflection screen 3 can increase the temperature gradient between the lower section 113 and the upper section 111 of the crucible 1, and the temperature of the lower section 113 is greater than that of the upper section 111. The lower section 113 has a high temperature, so that the raw material N located in the middle and lower section 113 starts to sublimate from the bottom of the crucible 1, and the sublimated gas is transported to the upper section 111. A seed crystal M is arranged inside the crucible cover 12, and since the temperature of the upper section 111 is lower than that of the lower section 113, the sublimated gas will start to crystallize on the surface of the seed crystal M. By setting the internal reflection screen 2 and the auxiliary side reflection screen 3, the purpose of increasing the temperature gradient between the upper section 111 and the lower section 113 can be achieved, which is beneficial to forming an effective temperature gradient between the high temperature zone of the raw material N and the low temperature zone of the seed crystal M. By adjusting the number of the internal reflection screen 2, the auxiliary side reflection screen 3 and the auxiliary upper reflection screen 4, the effective temperature gradient difference can be adjusted between 35°C and 200°C, thereby expanding the temperature gradient between the upper section 111 and the lower section 113 of the crucible 1, and being able to adjust a temperature gradient suitable for crystal growth, thereby improving the crystal quality.

[0036] Specifically, the auxiliary side reflection screen 3 can effectively block the heat radiation generated by the heater 9, so that the raw material N area is in a high temperature area, such as 2250-2350°C, and the seed crystal M area is in a low temperature area, such as 2150-2250°C, so that the effective temperature difference between the upper section 111 and the lower section 113 is adjustable at 35-200°C. The design of the internal reflection screen 2 in the annular portion 1121 allows the raw material N located in the middle section 1122 to be partially blocked by the internal reflection screen 2, while the raw material N located in the lower section 113 can be directly heated, which is conducive to the raw material N located in the lower section 113 of the crucible 1, that is, the bottom, to sublimate first, thereby improving the utilization rate of the raw material N. At the same time, the internal reflection screen 2 allows the raw material N at the bottom to sublimate first, reducing the sublimation of the raw material N at the side wall of the middle section 1122, which can first improve the uniformity of the temperature field of the raw material N, and also by reducing the sublimation of the raw material N at the side wall, it can also reduce the supersaturation of the gas component at the edge of the seed crystal M, thereby reducing the formation of polycrystalline.

[0037] The heater 9 is made of tungsten material and has a woven cage structure, and the crucible 1 can be a tungsten crucible 1. The crucible 1 is generally supported by a tungsten rod 13 and located inside the heater 9, and the tungsten rod 13 is generally connected to a lifting device outside the furnace body S1, so that the lifting movement of the crucible 1 inside the heater 9 can be achieved. Since the different positions of the crucible 1 in the heater 9 will also lead to differences in the temperature fields of the upper section 111 and the lower section 113, therefore, in combination with different stages of crystal growth, the size of the temperature gradient can be further adjusted by adjusting the position of the crucible 1, so as to better meet the crystal growth.

[0038] The crucible 1 provided in the embodiment of the present application is a special-shaped crucible 1, such as Figure 2 , Figure 3 As shown, the protruding portion of the middle section 112 can be used to accommodate the internal reflection screen 2. The wall thickness of the crucible body 11 can be 2mm, including the upper section 111, the middle section 112, the lower section 113 and the bottom wall. The inner diameter of the lower section 113 can be Φ60mm-100mm, and the height is about 30mm. The inner diameter of the middle section 112 of the crucible 1 can be Φ100mm-140mm, and the height is about 30mm. The inner diameter of the middle section 112 of the crucible 1 is 40mm larger than the inner diameter of the lower section 113 of the crucible 1, and the internal reflection screen 2 is placed. The inner diameter of the upper section 111 of the crucible 1 can be Φ60mm-100mm, and the height is about 60mm. The diameter of the crucible cover 12 can be Φ64mm-104mm.

[0039] The following will explain the control effect of the temperature field control device in combination with the basic process of crystal growth. At the beginning of growth, the crucible 1 is at the bottom of the heater 9. By controlling the power of the heater 9 to increase the temperature, the temperature at the top of the crucible 1 is increased to 2200-2250°C. At this time, the temperature at the bottom of the crucible 1 is 2150-2200°C. This heating process is an inversion heating process with a temperature difference range of 10-50°C. This process is to prevent the surface of the seed crystal M from premature nucleation and to perform thermal corrosion treatment on the surface of the seed crystal M. At this time, the temperature of the upper section 111 of the crucible 1 is relatively high because the middle section 112 and the lower section 113 of the crucible 1 are not located inside the heater 9. After the thermal corrosion treatment of the surface of the seed crystal M is completed, the crucible 1 is moved until it is completely located inside the heater 9. During the movement, the power of the heater 9 is controlled to maintain the top temperature of the crucible 1 at 2200-2250°C. After moving into place, due to the heat blocking effect of the internal reflection screen 2 and the auxiliary side reflection screen 3, the temperature of the lower section 113 of the crucible 1, that is, the bottom of the crucible 1, is higher, at 2300-2350°C. The air pressure is reduced, and the air pressure drops to 50-60KPa within 30-200 minutes, and crystal growth begins. At this time, the temperature difference between the seed crystal M and the raw material N is about 50-150°C, and the growth time is 100 hours. After the growth is completed, the air pressure is increased to 90-100KPa, and the crucible 1 is lowered to the bottom of the heater 9. At this time, the top temperature of the crucible 1 is 2200-2250°C, and the bottom temperature of the crucible 1 is 2150-2200°C. Then the temperature is reduced, and the power drops to 0 in 8-10 hours. The chamber drops to room temperature and the crucible 1 is taken out, and the crystal growth is completed. From the above experimental process and experimental data, it can be concluded that: under the premise that the heater 9 remains unchanged, and the auxiliary side reflection screen and the internal reflection screen 2 are fixed in structure, the temperature difference of the inversion field (the temperature of the upper section 111 is high and the temperature of the lower section 113 is low) at the beginning of growth is about 10-50°C, and during the growth process, the temperature difference of the positive temperature field (the temperature of the upper section 111 is low and the temperature of the lower section 113 is high) is about 50-150°C, and the temperature difference of the inversion field during the cooling process is 10-50°C. It can be seen that during the crystal growth process, the temperature field control device provided in the embodiment of the present application can expand the difference in temperature gradient between the upper section 111 and the lower section 113 in the crucible 1, which can reach 35°C-200°C. Compared with the prior art of only 10°C-35°C, it can meet the needs of crystal growth and avoid the problem of defects that are easy to occur due to too small temperature gradient.

[0040] In some embodiments of the present application, Figure 1 As shown, the temperature field control device also includes an auxiliary upper reflection screen 4 arranged above the crucible cover 12. The auxiliary upper reflection screen 4 has a first opening 41 in the middle, and the first opening 41 is coaxially arranged with the seed crystal M.

[0041] The auxiliary upper reflection screen 4 is disposed above the crucible cover 12 , and has a first opening 41 in the middle thereof, the first opening 41 being coaxially disposed with the seed crystal M; wherein the top of the auxiliary side reflection screen 3 is equal to or higher than the height of the auxiliary upper reflection screen 4 .

[0042] In this embodiment, the auxiliary upper reflection screen 4 arranged above the crucible cover 12 can enhance the heat preservation effect on the top of the crucible cover 12. By setting a first opening 41 on the auxiliary upper reflection screen 4, the first opening 41 and the seed crystal M are coaxially arranged, that is, the center line of the first opening 41 and the center line of the seed crystal M are colinear, that is, the first opening 41 of the auxiliary upper reflection screen 4 is arranged relative to the seed crystal M, which is beneficial to lowering the temperature of the seed crystal M and increasing the temperature around the seed crystal M, which is beneficial to the equal-diameter or even expanded-diameter growth of the single crystal, and inhibiting the growth of polycrystalline around the seed crystal M.

[0043] Alternatively, if Figure 1 As shown, the top of the auxiliary side reflection screen 3 is equal to or higher than the top of the auxiliary upper reflection screen 4. This can further block the heat from the side wall of the crucible 1 from entering the upper section 111 of the crucible 1, thereby facilitating the adjustment of the radial temperature field uniformity and increasing the temperature difference between the upper section 111 and the lower section 113 of the crucible 1.

[0044] In some embodiments of the present application, the size of the first opening 41 is equal to the diameter of the seed crystal M; or, the first opening 41 is a gradual opening, and the maximum size of the first opening 41 is equal to the diameter of the seed crystal M, and the minimum size is greater than or equal to 1 / 2 of the diameter of the seed crystal M.

[0045] The first opening 41 of the auxiliary upper reflection screen 4 is conducive to heat dissipation at the top of the crucible cover 12, so that the surface temperature of the seed crystal M arranged inside the crucible cover 12 is relatively low, forming supercooling, so that the sublimated gas begins to crystallize on the surface of the seed crystal M.

[0046] The first opening 41 may be an opening with a fixed size, such as Figure 1 As shown, the size of the first opening 41 is equal to the diameter of the seed crystal M, which can increase the heat dissipation area of ​​the first opening 41, reduce the surface temperature of the seed crystal M, and facilitate crystallization.

[0047] The first opening 41 may also be an opening with a gradually changing size, for example, the first opening 41 gradually becomes larger in the direction away from the crucible cover 12, and the first opening 41 is in an inverted trapezoid. Of course, the first opening 41 may also gradually decrease in the direction away from the crucible cover 12, and be in a right trapezoid. The maximum size of the first opening 41 does not exceed the diameter of the seed crystal M, and the minimum size is greater than or equal to 1 / 2 of the diameter of the seed crystal M. The inverted trapezoidal first opening 41 is conducive to heat dissipation at the top of the crucible cover 12, and it is easier to form a temperature gradient with low middle temperature and high edge temperature on the surface of the seed crystal M, so as to avoid the edge temperature of the seed crystal M from being too cold and forming polycrystalline. The right trapezoidal first opening 41 can slowly reduce the surface temperature of the seed crystal M to avoid local overcooling.

[0048] In some embodiments of the present application, Figure 1 , Figure 4As shown, the auxiliary side reflection screen 3 includes at least one first reflection layer 31 . When it includes two or more first reflection layers 31 , first support members 32 are arranged between adjacent first reflection layers 31 to separate the first reflection layers 31 .

[0049] The auxiliary side reflection screen 3 may include a first reflection layer 31. When only one layer is included, the thickness of the first reflection layer 31 may be slightly thicker. When the auxiliary side reflection screen includes two or more first reflection layers 31, the heat entering the middle and upper section 111 of the crucible 1 from the side wall may be further reduced through two reflections. It can be understood that when the auxiliary side reflection screen 3 includes two or more first reflection layers 31, the thickness of each first reflection layer 31 may be equal or unequal.

[0050] Optionally, the first support member may be a U-shaped support member, which can increase the support area between adjacent first reflective layers 31 and has a good support effect. A plurality of first support members 32 may be provided to prevent the first reflective layer 31 from softening and deforming at high temperatures and causing adhesion. The first support member 32 and the first reflective layer 31 are made of the same material, both of which may be tungsten plates. The spacing between the two first reflective layers 31 may be set to 5 mm-6 mm, which can play a good blocking role and prevent adhesion at high temperatures.

[0051] In some embodiments of the present application, Figure 1 As shown, the auxiliary upper reflective screen 4 includes at least two layers of second reflective layers 42. When two or more layers of second reflective layers 42 are included, a second support member is provided between adjacent second reflective layers 42 to separate the second reflective layers 42. The specific form of the second support member can be referred to Figure 4 .

[0052] The auxiliary upper reflection screen 4 may include a second reflection layer 42. When only one layer is included, the thickness of the second reflection layer 42 may be slightly thicker. When the auxiliary upper reflection screen 4 includes two or more second reflection layers 42, the heat entering from the upper part to the middle upper section 111 of the crucible 1 can be further reduced through two reflections when the temperature is raised in the inversion temperature field; when the crystal is grown in the positive temperature field, the heat loss in the middle upper end 111 of the crucible 1 can be reduced. It can be understood that when the auxiliary side reflection screen 3 includes two or more second reflection layers 42, the thickness of each first reflection layer 31 may be equal or unequal.

[0053] Optionally, the second support member may be a U-shaped support member, which can increase the support area between adjacent second reflective layers 42 and has a better support effect. A plurality of second support members may be provided to prevent the second reflective layer 42 from softening and deforming at high temperatures and causing adhesion. The second support member and the second reflective layer 42 are made of the same material, both of which may be tungsten plates. The spacing between the two layers of the second reflective layer 42 may be set to 5 mm-6 mm, which can play a good blocking role and prevent adhesion at high temperatures.

[0054] The auxiliary side reflection screen 3 may be composed of 2 to 8 layers of first reflection layers 31 , and the auxiliary upper reflection screen 4 may be composed of 2 to 8 layers of second reflection layers 42 .

[0055] It can be understood that in actual application, by increasing or decreasing the number of first reflective layers 31 and / or second reflective layers 42, the purpose of increasing or decreasing the temperature gradient can be achieved, thereby adjusting the temperature field simply and flexibly.

[0056] It should be noted that the internal reflection screen 2 may also be composed of one or two or more reflection layers. When there are multiple reflection layers, adjacent reflection layers are also separated by support members. The specific form of the support member can be referred to Figure 4 .

[0057] In some embodiments of the present application, Figure 5 As shown, the auxiliary side reflection screen 3 includes five first reflection layers 31, the outermost and second outermost first reflection layers 31 are supported on the middle section 112, the bottoms of the remaining three first reflection layers 31 are not in contact with the middle section 112, and the distance between each first reflection layer 31 and the middle section 112 increases successively along the direction approaching the side wall of the crucible 1.

[0058] In this embodiment, the auxiliary side reflection screen 3 is composed of five layers of first reflection layers 31, among which the bottom of the first reflection layer 31 located in the outermost layer and the second outermost layer is in contact with the upper surface of the middle section 112 protruding from the upper section 111 and the lower section 113, and is supported on the middle section 112. The remaining three layers are not in contact with the middle section 112, and the distance between the bottom and the middle section 112 increases as it approaches the side wall of the crucible 1, that is, the innermost first reflection layer 31 is the shortest. It should be noted that the top of the auxiliary side reflection screen 3 is roughly flush with each other, and there is no height difference.

[0059] The auxiliary side reflective screen 3 can make the temperature gradient change linearly through the above design. For example, during the growth process, the temperature drop from the raw material N to the seed crystal M is linear, and there will be no local temperature sudden cooling leading to uneven transportation of the raw material N, which will lead to a large amount of crystallization on the upper surface of the raw material. The crystallization on the upper surface of the raw material will hinder the transportation of the component gas volatilized from the raw material N, affecting the crystal growth.

[0060] In some embodiments of the present application, Figure 2 , Figure 3 As shown, a groove 121 is provided on the outer side of the crucible cover 12 corresponding to the position where the seed crystal M is set, and the diameter of the groove 121 is less than or equal to 1 / 2 of the diameter of the seed crystal M, for example, it can be 1 / 2, 1 / 3, 1 / 4 of the diameter of the seed crystal M, etc.

[0061] A groove 121 is provided on the outer side of the crucible cover 12 at a position corresponding to the seed crystal M. The groove 121 cooperates with the first opening 41 of the auxiliary upper reflective screen 4 to provide a suitable radial temperature gradient for crystal growth, which is conducive to the equal diameter or expanded diameter growth of single crystals and reduces the influence of stress caused by polycrystalline extrusion and large radial gradient. In addition, the heat preservation effect of the auxiliary upper reflective screen 4 is also conducive to improving the uniformity of the radial temperature field.

[0062] In some embodiments of the present application, the depth of the groove 121 is less than or equal to 1 / 2 of the thickness of the crucible cover 12, for example, it can be 1 / 2, 1 / 3, 1 / 4 of the thickness of the crucible cover 12. The groove 121 does not penetrate the crucible cover 12, so that the crucible cover 12 has both a heat preservation effect and a heat dissipation effect at the groove 121, which can provide a suitable radial temperature gradient for crystal growth.

[0063] As an embodiment, the thickness of the crucible cover 12 may be 10 mm-15 mm, and the depth of the middle groove 121 may be 4 mm-5 mm.

[0064] In some embodiments of the present application, Figure 2 , Figure 3 , Figure 6 , Figure 7 As shown, the temperature field control device includes a baffle 5, which is arranged inside the crucible 1 and located at the bottom of the upper section 111. The baffle 5 includes a hollow area 51 and a shielding area 52 arranged around the hollow area 51. The range of the hollow area 51 is consistent with the size of the seed crystal M.

[0065] The design of the baffle 5 can further block the upward transport of the side gas components, allowing the gas components to be transported upward in the middle hollow area 51 channel, so that the gas is concentrated in the center of the seed crystal M and crystallization begins from the center of the seed crystal M to the edge, which is more conducive to the growth of single crystals and reduces the formation of polycrystals.

[0066] In some embodiments of the present application, Figure 2 , Figure 3 As shown, a boss 1111 is provided at the bottom end of the inner wall of the upper section 111, and the baffle 5 is supported on the boss 1111. By providing the boss 1111 on the inner wall of the upper section 111, the baffle 5 can be placed on the boss 1111, which is convenient for disassembly. In this way, the baffle 5 can be placed on the upper wall after the raw material N is loaded, which is convenient for loading. After the crystal growth is completed, the baffle 5 can be taken down and put on again after the loading is completed.

[0067] Of course, in other embodiments, the crucible body 11 may be made into a split structure, the middle section 112 and the lower section 113 are an integrated structure, the upper section 111 and the middle section 112 are separately arranged, the baffle 5 is the bottom wall of the upper section 111, and the upper section 111 is placed on the middle section 112. That is to say, the upper section 111 of the crucible body 11 is made into a separate part, the bottom wall of the crucible 1 of the upper section 111 forms the above-mentioned baffle 5 structure, the upper section 111 of the crucible body 11 is placed on the middle section 112, and the bottom wall of the upper section 111 of the crucible body 11 plays the role of the baffle 5.

[0068] In some embodiments of the present application, Figure 6 As shown, the hollow area 51 includes a through hole 511; or Figure 7 As shown, the hollow area 51 includes a plurality of evenly arranged through holes 511 .

[0069] The hollow area 51 can be set as a large through hole 511, which can increase the gas transport speed. The hollow area 51 can also be set as a plurality of evenly arranged small through holes 511, and the gas is transported upward from the small through holes 511. The intervals between the small through holes 511 have a blocking effect on the gas, which can further improve the uniformity of the flow field.

[0070] In some embodiments of the present application, Figure 1 , Figure 5 As shown, the temperature field control device further includes: a lower reflection screen 7, a side reflection screen 8 and an upper reflection screen 6. The lower reflection screen 7 is located below the heater 9 and the crucible 1, and the lower reflection screen 7 includes a through hole 72. The side reflection screen 8 is cylindrical, and the side reflection screen 8 is sleeved on the outer periphery of the lower reflection screen 7. The upper reflection screen 6 covers the side reflection screen 8 or is internally connected to the side reflection screen 8, so that the lower reflection screen 7, the side reflection screen 8 and the upper reflection screen 6 form a hollow cavity, the crucible 1 and the auxiliary side reflection screen 3 are located in the cavity, and the upper reflection screen 6 has a second opening 62 opposite to the first opening 41 along the height direction, and the opening area of ​​the second opening 62 gradually decreases in the direction away from the crucible cover 12.

[0071] In this embodiment, the lower reflection screen 7, the side reflection screen 8 and the upper reflection screen 6 form a hollow cavity, and the crucible 1 and the auxiliary side reflection screen 3 are located in the cavity. It can be understood that when the temperature field control device includes the auxiliary upper reflection screen 4, the auxiliary upper reflection screen 4 is also located in the cavity. The heater 9 for heating is also located in the cavity. The lower reflection screen 7, the side reflection screen 8 and the upper reflection screen 6 reflect the heat radiated to their inner surfaces to the inside of the cavity, and play a role in heat preservation of the internal temperature field, thereby ensuring the stability of the temperature field in the crucible 1. The through hole 72 on the lower reflection screen 7 is used to support the tungsten rod 13 of the crucible 1 to pass through. The second opening 62 on the upper reflection screen 6 is used for heat dissipation at the top of the crucible cover 12, which is conducive to the formation of supercooling at the position of the crucible cover 12, which is conducive to the crystallization of gas on the surface. The opening area of ​​the second opening 62 gradually decreases in the direction away from the crucible cover 12, so that the heat at the top of the crucible cover 12 is slowly dissipated, and will not cause a large temperature field change at the top of the crucible cover 12, thereby ensuring the uniformity of the temperature gradient inside the crucible cover 12.

[0072] Optionally, for the embodiment in which the upper reflective screen 6 is inscribed in the side reflective screen 8, as a feasible method, the upper reflective screen 6 can be fixed to the wall side of the furnace cover S2 of the single crystal furnace, such as Figure 8 In the embodiment shown, the upper reflective screen 6 is fixed to the inner wall of the furnace cover S2. The upper reflective screen 6 can be opened along with the opening of the furnace cover S2, which makes the operation easier.

[0073] In some embodiments of the present application, Figure 1 , Figure 4 and Figure 5 As shown, the upper reflection screen 6 includes at least five layers of third reflection layers 61, and third supports are arranged between adjacent third reflection layers 61 to separate the third reflection layers 61. The lower reflection screen 7 includes at least five layers of fourth reflection layers 71, and fourth supports are arranged between adjacent fourth reflection layers 71 to separate the fourth reflection layers 71; the side reflection screen 8 includes at least five layers of fifth reflection layers 81, and fifth supports are arranged between adjacent fifth reflection layers 81 to separate the fifth reflection layers 81.

[0074] The upper reflection screen 6, the lower reflection screen 7 and the side reflection screen 8 are respectively composed of five or more reflection layers, and the thickness of each third reflection layer 61, the fourth reflection layer 71 and the fifth reflection layer 81 can be equal or unequal. The third support member, the fourth support member and the fifth support member can all be U-shaped support members, and the U-shaped support member can increase the support area between adjacent reflection layers and has a good support effect. The third support member, the fourth support member and the fifth support member can be provided in multiple numbers to avoid the adjacent reflection layers from softening and deforming under high temperature and adhesion. Among them, the manufacturing material of each support member can be the same as the manufacturing material of the corresponding reflection layer, for example, they can all be tungsten plates. The spacing between two adjacent reflection layers can be set to 5mm-6mm, which can play a good blocking role and avoid adhesion under high temperature.

[0075] Among them, the forms of the third support member, the fourth support member and the fifth support member can refer to Figure 4 The first support member 32 is provided in the middle.

[0076] As a feasible embodiment, the upper reflection screen 6 may be composed of 2 to 5 layers of the third reflection layer 61 , the lower reflection screen 7 may be composed of 2 to 5 layers of the fourth reflection layer 71 , and the side reflection screen 8 may be composed of 2 to 5 layers of the fifth reflection layer 81 .

[0077] The second aspect of the present application provides a single crystal furnace, such as Figure 8 As shown, the single crystal furnace includes: a furnace body S1, a furnace cover S2, a heater 9 and the temperature field control device described above. The inner wall of the furnace body S1 is provided with electrodes, and the furnace cover S2 covers the furnace body S1. The heater 9 is arranged inside the furnace body S1, and the two or three electrodes of the heater 9 are connected to the electrodes. The temperature field control device is placed inside the furnace body S1.

[0078] The single crystal furnace in this embodiment includes a temperature field control device, which can effectively expand the temperature gradient between the upper section 111 and the lower section 113 of the crucible 1, and can control the temperature gradient suitable for crystal growth, thereby improving the crystal quality.

[0079] It should be noted that the crucible 1 and the auxiliary side reflection screen 3 are both located inside the heater 9. When the temperature field control device includes an auxiliary upper reflection screen 4, the auxiliary upper reflection screen 4 is also located inside the heater 9. When the temperature field control device includes an upper reflection screen 6, a lower reflection screen 7 and a side reflection screen 8, the heater 9 is located in a cavity formed by the upper reflection screen 6, the lower reflection screen 7 and the side reflection screen 8, and the two or three poles of the heater 9 are connected to the electrodes through the avoidance groove provided on the auxiliary side reflection screen 3. The two or three poles of the heater 9 can be provided with insulating parts for protection to avoid short circuit with the auxiliary side reflection screen 3. When the single crystal furnace is powered by direct current, the electrodes of the heater 9 are two poles, and when the single crystal furnace is powered by alternating current, the electrodes of the heater 9 are three poles.

[0080] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0081] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0082] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A temperature field control device, characterized in that: include: A crucible (1), at least partly located inside a heater (9), comprising a crucible body (11) and a crucible cover (12) covering the crucible body (11); the crucible cover (12) is used to place a seed crystal (M); the crucible body (11) comprises an upper section (111), a middle section (112) and a lower section (113); the inner diameter of the middle section (112) is larger than that of the upper section (111) and the lower section (113); the middle section (112) comprises a middle section (1122) having the same inner diameter as that of the upper section (111) and the lower section (113) and an annular section (1121) having a diameter larger than that of the upper section (111) and the lower section (113); the middle section (1122) and the lower section (113) are used to contain a raw material (N); An internal reflection screen (2) is disposed in the annular portion (1121) and is used to reflect heat in a direction away from the crucible body (11); An auxiliary side reflection screen (3) is arranged outside the crucible (1) and supported on the middle section (112); the top end of the auxiliary side reflection screen (3) is higher than the top end of the crucible cover (12).

2. The temperature field control device according to claim 1, characterized in that: The temperature field control device further comprises an auxiliary upper reflection screen (4) arranged above the crucible cover (12), wherein the auxiliary upper reflection screen (4) has a first opening (41) in the middle, and the first opening (41) is coaxially arranged with the seed crystal (M).

3. The temperature field control device according to claim 2, characterized in that: The size of the first opening (41) is equal to the diameter of the seed crystal (M); or, the first opening (41) is a gradual opening, and the maximum size of the first opening (41) is equal to the diameter of the seed crystal (M), and the minimum size is greater than or equal to 1 / 2 of the diameter of the seed crystal (M).

4. The temperature field control device according to claim 2, characterized in that: The auxiliary side reflection screen (3) comprises at least one first reflection layer (31); when two or more first reflection layers (31) are included, first support members (32) are arranged between adjacent first reflection layers (31) to separate the first reflection layers (31); The auxiliary upper reflection screen (4) comprises at least one second reflection layer (42). When two or more second reflection layers (42) are included, a second support member is arranged between adjacent second reflection layers (42) to separate the second reflection layers (42).

5. The temperature field control device according to claim 4, characterized in that: The auxiliary side reflection screen (3) comprises five first reflection layers (31), the outermost and second outermost first reflection layers (31) are supported on the middle section (112), the bottoms of the remaining three first reflection layers (31) are not in contact with the middle section (112), and the distance between each first reflection layer (31) and the middle section (112) increases successively in a direction approaching the side wall of the crucible (1).

6. The temperature field control device according to claim 1, characterized in that: A groove (121) is provided on the outer side of the crucible cover (12) at a position corresponding to the location of the seed crystal (M), and the diameter of the groove (121) is less than or equal to 1 / 2 of the diameter of the seed crystal (M).

7. The temperature field control device according to claim 6, characterized in that: The depth of the groove (121) is less than or equal to 1 / 2 of the thickness of the crucible cover (12).

8. The temperature field control device according to claim 6, characterized in that: The temperature field control device comprises a baffle (5), the baffle (5) being arranged inside the crucible (1) and located at the bottom end of the upper section (111), the baffle (5) comprising a hollow area (51) and a shielding area (52) arranged around the hollow area (51), and the range of the hollow area (51) is consistent with the size of the seed crystal (M).

9. The temperature field control device according to claim 8, characterized in that: A boss (1111) is provided at the bottom end of the inner wall of the upper section (111), and the baffle (5) is supported on the boss (1111).

10. The temperature field control device according to claim 8, characterized in that: The hollow area (51) includes one through hole (511); or, the hollow area (51) includes a plurality of through holes (511) that are evenly arranged.

11. The temperature field control device according to any one of claims 1 to 10, characterized in that: The temperature field control device also includes: A lower reflection screen, located below the heater (9) and the crucible (1), the lower reflection screen comprising a through hole (72); A side reflection screen (8), the side reflection screen (8) is cylindrical and sleeved on the outer periphery of the lower reflection screen; An upper reflection screen (6), the upper reflection screen (6) covers the side reflection screen (8) or is inscribed in the side reflection screen (8), so that the lower reflection screen, the side reflection screen (8) and the upper reflection screen (6) form a hollow cavity, the crucible (1), the auxiliary side reflection screen (3) and the auxiliary upper reflection screen (4) are located in the cavity, the upper reflection screen (6) has a second opening (62) opposite to the first opening (41) in the height direction, and the opening area of ​​the second opening (62) gradually decreases in the direction away from the crucible cover (12).

12. The temperature field control device according to any one of claims 4 to 10, characterized in that: The first reflection layer (31) and the second reflection layer (42) are both tungsten plates; The first support member (32) and the second support member are both U-shaped pure tungsten members.

13. A single crystal furnace, characterized in that: The single crystal furnace comprises: A furnace body (S1), wherein an electrode is arranged on the inner wall of the furnace body (S1); A furnace cover (S2), covering the furnace body (S1); A heater (9) is arranged inside the furnace body (S1), and two or three electrodes of the heater (9) are connected to the electrodes; The temperature field control device according to any one of claims 1 to 12 is placed in the furnace body (S1).

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