Batch type aluminum nitride crystal growth furnace and growth method

Abstract

The invention discloses a batch type aluminum nitride crystal growth furnace and a growth method. The growth furnace comprises a furnace shell, a heat preservation screen structure, a heating component, a crucible body and the like. The crucible body consists of a crucible cover, a crucible bottom wall, a crucible outer wall, a crucible inner wall and a seed crystal supporting table; the inner wall of the crucible is a polygonal regular prism cylinder with a plurality of small holes distributed in the cylinder wall; the seed crystal supporting table is a polygonal regular prism with a through hole in the center; the seed crystal supporting table, the crucible inner wall and the crucible outer wall are sequentially sleeved on the crucible bottom wall from inside to outside, and the crucible cover covers the tops of the seed crystal supporting table, the crucible inner wall and the crucible outer wall to define a crucible cavity; wherein the crucible cavity is divided into a crystal growth chamber and a raw material accommodating chamber by the crucible inner wall. During crystal growth, a seed crystal is fixed on the outer side surface of the seed crystal supporting table, an aluminum nitride raw material is placed in the raw material accommodating chamber, and the aluminum nitride raw material is decomposed at high temperature to form a gas-phase substance which is transmitted to the surface of the seed crystal through the inner wall of the porous crucible. The design of the crucible body forms a plurality of crystal horizontal growth systems which are circumferentially distributed around the seed crystal supporting table, so that batch type aluminum nitride crystal growth is realized.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor material preparation, and in particular to a batch aluminum nitride crystal growth furnace and a batch aluminum nitride crystal growth method. Background Art

[0002] Aluminum nitride (AlN) is a third-generation wide bandgap semiconductor material with high bandgap width (6.2eV), high thermal conductivity (340W / (m·K)), high breakdown field strength (11.7MV / cm), good ultraviolet transmittance, chemical and thermal stability and other excellent properties. It can be widely used in the manufacture of laser diodes, optical receivers, ultra-high integrated circuits, microwave devices, lasers, optoelectronics, radiation-resistant, high-temperature resistant devices, etc. Although devices based on aluminum nitride single crystal substrates have broad application prospects, there are still great difficulties and challenges in the growth of aluminum nitride crystals and the preparation of their substrates, making it difficult to achieve high-quality, large-size, and high-yield production.

[0003] Physical vapor transport (PVT) has been proven to be an efficient method for growing large-size, high-quality aluminum nitride single crystal ingots. The traditional aluminum nitride PVT growth furnace only has one crucible system, which grows a single aluminum nitride crystal by fixing a single seed crystal. Due to the slow crystal growth rate of the PVT method and the preparation cycle of up to 1-2 weeks, the preparation and production efficiency is extremely low. Especially for aluminum nitride, which has high technical difficulty in growing and is prone to growing crystals of poor quality, the yield of aluminum nitride single crystal substrate preparation is extremely low and the preparation cost is high, making it difficult to develop quickly and with high quality. Therefore, it is urgent to develop an efficient and low-cost aluminum nitride crystal growth device and growth method to improve the production efficiency and capacity of aluminum nitride crystals, reduce production costs, and thus promote the industrialization of aluminum nitride materials. Summary of the invention

[0004] The present invention provides a batch aluminum nitride crystal growth furnace and a growth method. By constructing a multi-directional resistive heater distribution and a special design of a crucible system, a circularly distributed batch aluminum nitride crystal horizontal growth system is formed, and a single furnace synchronous growth of multiple aluminum nitride crystals is achieved, which greatly improves the preparation efficiency and production capacity of aluminum nitride crystals and significantly reduces the preparation cost.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions.

[0006] Firstly, the present invention provides a batch type aluminum nitride crystal growth furnace, which comprises: a furnace shell, a heat preservation screen structure, a heating component, a crucible body and a support column for supporting the entire crucible body.

[0007] The furnace shell encloses the outermost layer of the entire growth furnace, and circulating cooling water is introduced into the furnace shell to maintain the thermal balance of the entire growth furnace system.

[0008] The heat-insulating screen structure is located in the furnace shell, and comprises a top heat-insulating screen, a bottom heat-insulating screen and a cylindrical side heat-insulating screen, which are respectively arranged at the top, bottom and periphery of the heating component.

[0009] The heating component is a plurality of resistive heaters distributed around the crucible body, including a top heater, a bottom heater, and a cylindrical middle heater and a cylindrical side heater coaxial with the central axis, which are used to heat the top, bottom and inner and outer peripheries of the crucible body respectively.

[0010] The crucible body is arranged in the space enclosed by the cylinder walls of the middle heater and the side heaters, and includes a crucible cover, a crucible bottom wall, a crucible outer wall, a crucible inner wall, and a seed crystal support; wherein the crucible outer wall is cylindrical; the crucible inner wall is an m-sided regular prism cylinder, m refers to the number of bottom sides of the regular prism cylinder, m≧3, and a number of small holes penetrating the cylinder wall are evenly distributed on the inner wall of the crucible; the seed crystal support is an n-sided regular prism, and a cylindrical through hole penetrating the upper and lower bottom surfaces is arranged in the center of the regular prism, and the middle heater is placed in the cylindrical through hole of the seed crystal support, wherein n refers to the number of bottom sides of the regular prism seed crystal support, n≧3, and n=m; the seed crystal support, the crucible inner wall, and the crucible outer wall are of the same height, are sequentially mounted on the crucible bottom wall from the inside to the outside, and the central axes of the three are coaxially installed, and the crucible cover covers the top of the three. The crucible cover, the outer wall of the crucible, the bottom wall of the crucible, and the seed crystal support form a closed space, which is the crucible cavity; the inner wall of the crucible is placed in the crucible cavity to divide the cavity of the crucible cavity into two parts, wherein the cavity surrounded by the crucible cover, the inner wall of the crucible, the seed crystal support and the bottom wall of the crucible is the crystal growth chamber; wherein the cavity surrounded by the crucible cover, the inner wall of the crucible, the outer wall of the crucible and the bottom wall of the crucible is the raw material holding chamber. The bottom wall of the crucible is placed on the support column, and the entire crucible body is supported by the support column, and the support column can move up and down to adjust the relative position of the crucible body and the top heater and the bottom heater.

[0011] The edge length (i.e., the height of the seed crystal support) and the bottom length of the regular prism seed crystal support are both greater than the diameter of the seed crystal used for crystal growth. When the growth furnace is working, the seed crystal is fixed on each outer side surface of the seed crystal support (i.e., each side surface facing the inner wall of the crucible), and each outer side surface accommodates at least one seed crystal; the aluminum nitride raw material required for crystal growth is placed in the raw material holding chamber; by adjusting the output power of the middle heater, the side heater, the top heater, and the bottom heater, a reasonable temperature distribution is formed in which the temperature of the raw material inside the crucible cavity, i.e., the temperature of the raw material holding chamber is high and the temperature of the seed crystal in the crystal growth chamber is low. The aluminum nitride raw material decomposes and sublimates at high temperature to form a gas phase substance, which is transmitted to the relatively low temperature seed crystal surface through a number of small holes distributed on the inner wall of the crucible, and aluminum nitride crystals grow on the seed crystal surface. In this process, the high temperature to low temperature thermal field from the raw material to each seed crystal in the crucible cavity is horizontally distributed, that is, multiple aluminum nitride crystal horizontal growth systems distributed in a circular manner around the seed crystal support are formed, thereby realizing the synchronous growth of multiple aluminum nitride crystals in a single furnace, i.e., batch aluminum nitride growth.

[0012] Furthermore, the distance between the inner wall of the crucible and the seed crystal support is 5-100 mm.

[0013] Furthermore, the inner diameter of the cylindrical middle heater is 20-100 mm, and the distance between the middle heater and the seed crystal support is 10-50 mm.

[0014] Furthermore, the distance between the side heater and the outer wall of the crucible is 10-50 mm.

[0015] Furthermore, the top heater and the bottom heater are both in the shape of flat plates, and are 10-50 mm away from the crucible cover and the bottom wall of the crucible respectively, and the distance is adjusted by moving the support column up and down.

[0016] Furthermore, the top heat preservation screen and the bottom side heat preservation screen are flat-plate-shaped, the heat preservation screen structure comprises each heat preservation screen with the nearest adjacent surface of the heater at a distance of 10-100 mm, and the spacing between each heat preservation screen and the furnace shell is 30-300 mm.

[0017] Furthermore, seed crystal holders of different sizes are matched according to the size of the seed crystal used for crystal growth, so that the edge length (i.e., the height of the seed crystal holder) and the bottom length of the regular prism seed crystal holder are both greater than the diameter of the seed crystal used for crystal growth. In the embodiments of the present invention, the inventors used seed crystals of sizes of 2 inches, 4 inches, and 6 inches.

[0018] Furthermore, when the seed crystal tray is loaded with 2-inch seed crystals, the number of pieces that can be loaded at one time can be 3-20 pieces, that is, the number of bottom edges n of the seed crystal tray and the number of bottom edges m of the inner wall of the crucible satisfy: 3≤n≤20, 3≤m≤20; when loading 4-inch seed crystals, the number of pieces that can be loaded at one time can be 3-10 pieces, that is, the number of bottom edges n of the seed crystal tray and the number of bottom edges m of the inner wall of the crucible satisfy: 3≤n≤10, 3≤m≤10; when loading 6-inch seed crystals, the number of pieces that can be loaded at one time can be 3-8 pieces, that is, the number of bottom edges n of the seed crystal tray and the number of bottom edges m of the inner wall of the crucible satisfy: 3≤n≤8, 3≤m≤8.

[0019] Furthermore, assuming that the inner diameter of the outer wall of the crucible is D, and the diameter of the circumscribed circle of the outer side surface of the inner wall of the crucible is d, both satisfy the following conditions: (1) D>d; (2) [Dd*cos(π / m)] / 2≥5 (where D and d are in millimeters), where m is the number of the bottom sides of the inner wall of the crucible.

[0020] The present invention also provides a method for using the above-mentioned growth furnace, that is, a method for growing aluminum nitride crystals in batches, wherein the crystal growth uses the above-mentioned batch-type aluminum nitride crystal growth furnace, and the steps are as follows:

[0021] Step 1: fix multiple seed crystals to the outer sides of the seed crystal support, load the aluminum nitride raw material into the raw material holding chamber, cover the crucible cover, and then load the crucible body onto the support column. The seed crystal can be one or more substrate sheets or epitaxial wafers of aluminum nitride, silicon carbide, gallium nitride, sapphire, gallium oxide, and diamond. In various embodiments of the present invention, the aluminum nitride raw material is a high-purity ceramic block aluminum nitride raw material that has been purified and fired at a high temperature greater than 1900°C, but is not limited thereto.

[0022] Step 2: Close the furnace and evacuate the crucible chamber to 10 -4 Pa; turn on the heater and heat up to the surface temperature T of the aluminum nitride raw material within t1 time; s-1 and the seed crystal surface temperature T c-1 .

[0023] Step 3: introduce high-purity nitrogen into the crucible cavity to maintain the pressure P1; adjust the power of each heater and heat the crucible to the surface temperature T of the aluminum nitride raw material within t2. s-2 and the seed crystal surface temperature T c-2 ; Change nitrogen pressure to P2.

[0024] Step 4: Maintain T s-2 , T c-2 Keep unchanged with P2 and keep warm for t3 time.

[0025] Step 5: After the heat preservation is finished, the heater power is adjusted and the temperature is lowered to room temperature within time t4, and the grown multiple aluminum nitride ingots are taken out.

[0026] Preferably, in step 2, T s-1 500-1500℃, T c-1 is 500-1500℃, t1 is 0.5-

[0027] 5h.

[0028] Preferably, in step 3, P1 is 0.5-5 bar, T s-2 1900-2350℃, T c-1 is 1800-2300℃, and T s-2 Greater than T c-2 , t2 is 1-20h, P2 is 0.5-5bar.

[0029] Preferably, in step 4, t3 is 5-500h.

[0030] Preferably, the t4 in step five is 0.5-50h.

[0031] Furthermore, the thickness of the aluminum nitride ingot obtained in step five is 5-100 mm.

[0032] The present invention achieves the following beneficial effects:

[0033] (1) The batch aluminum nitride crystal growth furnace of the present invention can realize the synchronous growth of multiple aluminum nitride crystals in a batch, greatly improving the production efficiency and capacity of aluminum nitride crystals and effectively reducing the manufacturing cost.

[0034] (2) The batch aluminum nitride crystal growth furnace of the present invention adopts a horizontal growth system (the seed crystal and the raw material are on the same horizontal line), and makes full use of the axially symmetrical structure of the crucible body design, so that the crucible body contains multiple growth systems, and the same growth environment is formed in different growth systems, thereby improving the consistency and uniformity of batch preparation of multiple aluminum nitride crystals.

[0035] (3) The batch aluminum nitride crystal growth furnace of the present invention can be loaded with aluminum nitride seed crystals of different diameters (2-6 inches), and can stably prepare aluminum nitride crystals of different diameters, which greatly improves the compatibility of aluminum nitride of different sizes and is conducive to the iterative high-quality development of larger-sized aluminum nitride crystals.

[0036] (4) The batch aluminum nitride crystal growth furnace of the present invention adopts four groups of heaters in the middle, side, top and bottom, which can flexibly adjust the temperature and temperature field distribution of the seed crystal, raw material and the inside of the growth chamber, which is conducive to the high-quality and efficient growth and batch preparation of aluminum nitride.

[0037] (5) The batch-type aluminum nitride crystal growth furnace of the present invention adopts a design of a polygonal regular prism seed crystal support, the side of which is convenient for loading flat seed crystals. Combined with the reasonable layout of multiple heaters, the same thermal environment can be formed near multiple seed crystals; the growth furnace adopts a polygonal regular prism cylindrical crucible inner wall with holes, corresponding to the regular prism seed crystal support with the same number of bottom sides, forming a parallel structure growth space, which is conducive to the uniform horizontal transmission of materials.

[0038] (6) The inner wall of the crucible in the crucible cavity of the batch aluminum nitride crystal growth furnace of the present invention divides the crucible cavity into a crystal growth chamber and a raw material holding chamber. The opening design of the inner wall of the crucible will help the gas phase material decomposed from the raw material to flow through the wall holes to form a more stable flow rate and material flux, providing more stable material transmission and supply for the growth of aluminum nitride crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The figure is a schematic structural diagram of a batch type aluminum nitride crystal growth furnace of the present invention.

[0040] Figure 2 It is a schematic diagram of material transport for aluminum nitride growth according to the present invention.

[0041] Figure 3 1. A top view of a 2-inch batch aluminum nitride crystal growth furnace according to Example 1 of the present invention.

[0042] Figure 4 This is a top view of a 4-inch batch aluminum nitride crystal growth furnace according to Example 2 of the present invention.

[0043] Figure 5 This is a top view of a 6-inch batch aluminum nitride crystal growth furnace according to Example 3 of the present invention.

[0044] Figure 6 The 6-inch batch aluminum nitride crystal growth furnace of Example 3 of the present invention is Figure 1 The top view of the three-dimensional structure without the crucible cover at the AA position.

[0045] Among them: 1 is a seed crystal, 2 is a seed crystal support, 3 is an aluminum nitride raw material, 4 is an inner wall of a crucible, 5 is an outer wall of a crucible, 6 is a crucible cover, 7 is a bottom wall of a crucible, 8 is a crucible body support column, 9 is a middle heater, 10 is a side heater, 11 is a top heater, 12 is a bottom heater, 13 is a side insulation screen, 14 is a top insulation screen, 15 is a bottom insulation screen, and 16 is a furnace shell. DETAILED DESCRIPTION

[0046] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0047] A schematic diagram of the structure of a batch aluminum nitride crystal growth furnace used in each embodiment of the present invention is shown in FIG. Figure 1 As shown. The crucible body is composed of a seed crystal support 2, a crucible outer wall 5, a crucible cover 6, a crucible bottom wall 7, and a perforated crucible inner wall 4. The first four enclose a crucible cavity, and the crucible cavity is divided into two by the crucible inner wall, forming a raw material holding chamber enclosed by the seed crystal support 2, the crucible inner wall 4, the crucible cover 6 and the crucible bottom wall 7, and a crystal growth chamber enclosed by the crucible inner wall 4, the crucible outer wall 5, the crucible cover 6 and the crucible bottom wall 7. The aluminum nitride raw material 3 is placed in the raw material holding chamber, and the seed crystal 1 is fixed on the outer surface of the seed crystal support 2 by bonding, mechanical fixation, etc. When the growth furnace is working, the aluminum nitride raw material decomposes and sublimates at high temperature to form a gas phase substance, which is transmitted to the relatively low temperature surface of the seed crystal 1 through the porous crucible inner wall 4 to provide material for crystal growth. The material transmission schematic diagram is shown as follows Figure 2 As shown. The entire crucible body is supported by a crucible body support column 8. The heating system consists of a middle heater 9, a side heater 10, a top heater 11 and a bottom heater 12, which are respectively placed in the center, the surrounding side, the top and the bottom of the crucible body; the heat preservation screen includes a side heat preservation screen 13, a top heat preservation screen 14 and a bottom heat preservation screen 15, which surround the heaters to enclose each heater and block the heat loss of the heaters; the outermost layer of the entire device is a furnace shell 16, and cooling water is passed into the furnace shell 17 to take away the residual heat inside, thereby achieving thermal balance of the entire system.

[0048] Example 1

[0049] In this embodiment, 2-inch aluminum nitride crystals are grown in batches.

[0050] S1: Schematic diagram of the structure of a batch-type aluminum nitride crystal growth furnace Figure 1 and 2 inch batch aluminum nitride crystal growth furnace top view Figure 3The crucible system of this embodiment is assembled as follows: 8 pieces of 2-inch aluminum nitride seed crystals 1 are selected. The aluminum nitride seed crystals are fixed to the 8 outer surfaces of the regular octagonal prism-shaped seed crystal holder 2 after double-sided chemical mechanical polishing. The fixing method can be chemical bonding or mechanical fixing. The seed crystal holder 2, the octagonal regular prism-shaped perforated crucible inner wall 4 and the crucible outer wall 5 are placed on the crucible bottom wall 7, wherein the distance between the crucible inner wall 4 and the seed crystal holder 2 is 70 mm. The high-purity aluminum nitride raw material 3 after high-temperature purification is loaded into the raw material holding chamber, covered with the crucible cover 6, and then the entire device is placed on the crucible body support column 8. The crucible device, heat preservation screen and heater in the furnace are all made of high-temperature resistant pure tungsten and molybdenum materials.

[0051] S2: Close the furnace, move the crucible support column 8 to the specified position. Move the middle heater 9, side heater 10, top heater 11 and bottom heater 12 to the specified position, so that the closest distance to the crucible is 20 mm. Then evacuate to 10 -4 The heater is turned on, and after 4 hours of heating, the surface temperature of the aluminum nitride raw material is 1400°C and the surface temperature of the seed crystal 1 is 1300°C;

[0052] S3: Introduce high-purity nitrogen to maintain the pressure at 1.5 bar. Adjust the power of each heater and increase the temperature. After 18 hours, the surface temperature of the aluminum nitride raw material is raised to 2350°C and the surface temperature of the seed crystal 1 is raised to 2250°C. Change the nitrogen pressure to 0.8 bar;

[0053] S4: Maintain the surface temperature of the aluminum nitride raw material at 2350°C, the surface temperature of the seed crystal 1 at 2250°C, and the nitrogen pressure at 0.8 bar for 300 hours;

[0054] S5: Adjust the heater power and slowly cool down to room temperature for 30 hours. Take out the four grown aluminum nitride ingots. The thickness of each aluminum nitride ingot is about 40 mm.

[0055] Embodiment 2:

[0056] In this embodiment, 4-inch aluminum nitride crystals are grown in batches.

[0057] S1: Schematic diagram of the structure of a batch-type aluminum nitride crystal growth furnace Figure 1 and 4 inch batch aluminum nitride crystal growth furnace top view Figure 4The crucible system of this embodiment is assembled as follows: 5 4-inch gallium nitride seed crystals 1 are selected. The gallium nitride seed crystals 1 are fixed to the five outer surfaces of the regular pentagonal prism-shaped seed crystal holder 2 after double-sided chemical mechanical polishing. The fixing method can be chemical bonding or mechanical fixing. The seed crystal holder 2, the five-sided regular prism-shaped perforated crucible inner wall 4 and the crucible outer wall 5 are placed on the crucible bottom wall 7, wherein the distance between the crucible inner wall 4 and the seed crystal holder 2 is 50 mm. The high-purity aluminum nitride raw material 3 after high-temperature purification is loaded into the raw material holding chamber, covered with the crucible cover 6, and then the entire device is placed on the crucible body support column 8. The crucible device, heat preservation screen and heater in the furnace are all made of high-temperature resistant pure tantalum and molybdenum materials.

[0058] S2: Close the furnace, move the crucible support column 8 to the specified position. Move the middle heater 9, side heater 10, top heater 11 and bottom heater 12 to the specified position, so that the closest distance to the crucible is 30 mm. Then evacuate to 10 -4 The heater is turned on, and after 3 hours of heating, the surface temperature of the aluminum nitride raw material is 1200°C and the surface temperature of the seed crystal 1 is 1000°C;

[0059] S3: Introduce high-purity nitrogen to maintain the pressure at 2 bar. Adjust the power of each heater and increase the temperature. After 14 hours, the surface temperature of the aluminum nitride raw material is raised to 2230°C and the surface temperature of the seed crystal 1 is raised to 2150°C. Change the nitrogen pressure to 1.2 bar;

[0060] S4: Maintain the surface temperature of the aluminum nitride raw material at 2230°C, the surface temperature of the seed crystal 1 at 2150°C, and the nitrogen pressure at 1.2 bar for 200 hours;

[0061] S5: Adjust the heater power and slowly cool down to room temperature for 15 hours. Take out the four grown aluminum nitride ingots. The thickness of each aluminum nitride ingot is about 25 mm.

[0062] Embodiment 3:

[0063] In this embodiment, 6-inch aluminum nitride crystals are grown in batches.

[0064] S1: Figure 5 This is a top view of a 6-inch batch aluminum nitride crystal growth furnace of this embodiment. Figure 6 The 6-inch batch aluminum nitride crystal growth furnace of this embodiment is shown in Figure 1 The top view of the three-dimensional structure without the crucible cover at the AA position.

[0065] The crucible system of this embodiment is assembled as follows: 4 6-inch silicon carbide seed crystals 1 are selected. The silicon carbide seed crystals 1 are fixed to the four outer surfaces of the regular tetrahedral seed crystal holder 2 after double-sided chemical mechanical polishing. The fixing method can be chemical bonding or mechanical fixing. The seed crystal holder 2, the four-sided regular prism-shaped perforated crucible inner wall 4 and the crucible outer wall 5 are placed on the crucible bottom wall 7, wherein the distance between the crucible inner wall 4 and the seed crystal holder 2 is 30 mm. The high-purity aluminum nitride raw material 3 after high-temperature purification is loaded into the raw material holding chamber, covered with the crucible cover 6, and then the entire device is placed on the crucible body support column 8. The crucible device, heat preservation screen and heater in the furnace are all made of high-temperature resistant pure rhenium and molybdenum materials.

[0066] S2: Close the furnace, move the crucible support column 8 to the specified position. Move the middle heater 9, side heater 10, top heater 11 and bottom heater 12 to the specified position, so that the closest distance to the crucible is 40 mm. Then evacuate to 10 -4 The heater was turned on, and after 2 hours of heating, the surface temperature of the aluminum nitride raw material was 1000°C and the surface temperature of the seed crystal 1 was 800°C.

[0067] S3: Introduce high-purity nitrogen to maintain the pressure at 1 bar. Adjust the power of each heater and increase the temperature. After 10 hours, the surface temperature of the aluminum nitride raw material is raised to 1950°C and the surface temperature of the seed crystal 1 is raised to 1850°C. Change the nitrogen pressure to 0.5 bar.

[0068] S4: Maintain the surface temperature of the aluminum nitride raw material at 1950° C., the surface temperature of the seed crystal 1 at 1850° C., and the nitrogen pressure at 0.5 bar for 100 hours.

[0069] S5: Adjust the heater power and slowly cool down to room temperature for 5 hours. Take out the four grown aluminum nitride ingots. The thickness of each aluminum nitride ingot is about 15 mm.

[0070] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A batch type aluminum nitride crystal growth furnace, characterized in that: The growth furnace comprises: a furnace shell, a heat preservation screen structure, a heating component, a crucible body and a support column for supporting the entire crucible body; The furnace shell is the outermost layer of the entire growth furnace, and circulating cooling water is introduced into the furnace shell to maintain the thermal balance of the entire growth furnace system; The heat preservation screen structure is located in the furnace shell, and includes a top heat preservation screen, a bottom heat preservation screen and a cylindrical side heat preservation screen, which are respectively arranged at the top, bottom and periphery of the heating component; The heating component is a plurality of resistive heaters distributed around the crucible body, including a top heater, a bottom heater, and a cylindrical middle heater and a cylindrical side heater coaxial with a central axis, respectively used to heat the top, bottom and inner and outer peripheries of the crucible body; The crucible body is arranged in the space enclosed by the cylinder walls of the middle heater and the side heater, including a crucible cover, a crucible bottom wall, a crucible outer wall, a crucible inner wall, and a seed crystal support platform; wherein the crucible outer wall is cylindrical; the crucible inner wall is an m-sided regular prism cylinder, m refers to the number of bottom sides of the regular prism cylinder, m≧3, and a number of small holes penetrating the cylinder wall are evenly distributed on the inner wall of the crucible; the seed crystal support platform is an n-sided regular prism, and a cylindrical through hole penetrating the upper and lower bottom surfaces is arranged in the center of the regular prism, and the middle heater is placed in the cylindrical through hole of the seed crystal support platform, wherein n refers to the number of bottom sides of the regular prism seed crystal support platform, n≧3, and n=m; the seed crystal support platform, the crucible inner wall, and the crucible outer wall are of the same height, from the inside to the outside. The outer wall of the crucible is sequentially mounted on the bottom wall of the crucible, and the central axes of the three are coaxially installed, and the crucible cover is covered on the top of the three; the crucible cover, the outer wall of the crucible, the bottom wall of the crucible, and the seed crystal support platform enclose a closed space, which is the crucible cavity; the inner wall of the crucible is placed in the crucible cavity to divide the cavity of the crucible cavity into two, wherein the cavity enclosed by the crucible cover, the inner wall of the crucible, the seed crystal support platform and the bottom wall of the crucible is the crystal growth chamber; wherein the cavity enclosed by the crucible cover, the inner wall of the crucible, the outer wall of the crucible and the bottom wall of the crucible is the raw material holding chamber; the bottom wall of the crucible is placed on the support column, and the entire crucible body is supported by the support column, and the support column can move up and down to adjust the relative position of the crucible body and the top heater and the bottom heater; When the growth furnace is working, the seed crystals are fixed on the outer side surfaces of the seed crystal support platform, and each outer side surface accommodates at least one seed crystal; the aluminum nitride raw material required for crystal growth is placed in the raw material accommodating chamber.

2. The batch aluminum nitride crystal growth furnace according to claim 1, characterized in that: The size of the bottom side or height of the seed crystal support is matched according to the size of the seed crystal used for crystal growth, so that the height and bottom side length of the regular prism seed crystal support are both greater than the diameter of the seed crystal used for crystal growth.

3. The batch aluminum nitride crystal growth furnace according to claim 2, characterized in that: When the seed crystal tray is loaded with 2-inch seed crystals, the number of seed crystals loaded in a single furnace is 3-20 pieces, that is, the number of bottom sides n of the seed crystal tray and the number of bottom sides m of the inner wall of the crucible satisfy: 3≤n≤20, 3≤m≤20; when loaded with 4-inch seed crystals, the number of seed crystals loaded in a single furnace is 3-10 pieces, that is, the number of bottom sides n of the seed crystal tray and the number of bottom sides m of the inner wall of the crucible satisfy: 3≤n≤10, 3≤m≤10; when loaded with 6-inch seed crystals, the number of seed crystals loaded in a single furnace is 3-8 pieces, that is, the number of bottom sides n of the seed crystal tray and the number of bottom sides m of the inner wall of the crucible satisfy: 3≤n≤8, 3≤m≤8.

4. The batch aluminum nitride crystal growth furnace according to claim 1, characterized in that: The distance between the inner wall of the crucible and the seed crystal support platform is 5-100 mm.

5. The batch aluminum nitride crystal growth furnace according to claim 1, characterized in that: The inner diameter of the cylindrical middle heater is 20-100 mm, and the distance between the middle heater and the seed crystal support is 10-50 mm.

6. The batch type aluminum nitride crystal growth furnace according to claim 1, characterized in that: The distance between the side heater and the outer wall of the crucible is 10-50 mm.

7. The batch aluminum nitride crystal growth furnace according to claim 1, characterized in that: The top heater and the bottom heater are both in the shape of flat plates, and are 10-50 mm away from the crucible cover and the bottom wall of the crucible respectively. The distance is adjusted by moving the support column up and down.

8. The batch type aluminum nitride crystal growth furnace according to claim 1, characterized in that: The top heat preservation screen and the bottom side heat preservation screen are flat plate-shaped. The heat preservation screen structure comprises each heat preservation screen and the nearest adjacent surface of the heater at a distance of 10-100 mm, and the spacing between each heat preservation screen and the furnace shell is 30-300 mm.

9. The batch aluminum nitride crystal growth furnace according to claim 1, characterized in that: Assume that the inner diameter of the outer wall of the crucible is D, and the diameter of the circumscribed circle of the outer side surface of the inner wall of the crucible is d, and both satisfy: Formula 1) D>d; Formula 2) [Dd*cos(π / m)] / 2≥5, where m is the number of bottom sides of the inner wall of the crucible, and the units of D and d in Formula 2) are millimeters.

10. A method for growing aluminum nitride crystals in batches, characterized in that: The crystal growth uses the batch aluminum nitride crystal growth furnace described in any one of claims 1 to 9, the seed crystals used for crystal growth are fixed on the outer side surfaces of the seed crystal support, and each outer side surface accommodates at least one seed crystal; the aluminum nitride raw material required for crystal growth is placed in the raw material holding chamber; by adjusting the output power of the middle heater, the side heater, the top heater, and the bottom heater, a temperature distribution is formed in which the temperature at the raw material inside the crucible cavity, i.e., the raw material holding chamber is high and the temperature at the seed crystal in the crystal growth chamber is low, the aluminum nitride raw material decomposes and sublimates at high temperature to form a gas phase substance, which is transmitted to the relatively low temperature seed crystal surface through a number of small holes distributed on the inner wall of the crucible, and aluminum nitride crystals grow on the seed crystal surface; during the crystal growth process, the high temperature to low temperature thermal field from the raw material to each seed crystal in the crucible cavity is horizontally distributed, i.e., a plurality of aluminum nitride crystal horizontal growth systems distributed in a circular manner around the seed crystal support are formed, and a plurality of aluminum nitride crystals are synchronously grown in a single furnace, i.e., the batch aluminum nitride crystal growth.

11. The method for growing aluminum nitride crystals in batches according to claim 10, characterized in that: The steps include: Step 1, fixing a plurality of seed crystals on the outer sides of the seed crystal support, loading the aluminum nitride raw material into the raw material holding chamber, covering the crucible with a lid, and then loading the crucible body onto a support column; Step 2: Close the furnace and evacuate the crucible chamber to 10 -4 Pa; turn on the heater and heat up to the surface temperature T of the aluminum nitride raw material within t1 time; s-1 and the seed crystal surface temperature T c-1 ; Step 3: introduce high-purity nitrogen into the crucible cavity to maintain the pressure P1; adjust the power of each heater and heat the crucible to the surface temperature T of the aluminum nitride raw material within t2. s-2 and the seed crystal surface temperature T c-2 ; Change nitrogen pressure to P2; Step 4: Maintain T s-2 、T c-2 Keep P2 unchanged and keep warm for t3 time; Step 5: After the heat preservation is finished, the heater power is adjusted and the temperature is lowered to room temperature within time t4, and the grown multiple aluminum nitride ingots are taken out.

12. The method for growing aluminum nitride crystals in batches according to claim 11, characterized in that: In step 2, T s-1 500-1500℃, T c-1 It is 500-1500℃, and t1 is 0.5-5h.

13. The method for growing aluminum nitride crystals in batches according to claim 11, characterized in that: In step 3, P1 is 0.5-5 bar, T s-2 1900-2350℃, T c-1 is 1800-2300℃, and T s-2 Greater than T c-2 , t2 is 1-20h, P2 is 0.5-5bar.

14. The method for growing aluminum nitride crystals in batches according to claim 11, characterized in that: In the step 4, t3 is 5-500h.

15. The method for growing aluminum nitride crystals in batches according to claim 11, characterized in that: The t4 in the step 5 is 0.5-50h.

16. The method for growing aluminum nitride crystals in batches according to claim 11, characterized in that: The thickness of the aluminum nitride ingot obtained in step five is 5-100 mm.

17. The method for growing aluminum nitride crystals in batches according to claim 11, characterized in that: The seed crystal is selected from one or more substrate sheets or epitaxial sheets of aluminum nitride, silicon carbide, gallium nitride, sapphire, gallium oxide, and diamond.

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