Integrated horizontal silicon carbide boat and preparation method thereof

Abstract

The invention belongs to the technical field of precise ceramic parts for semiconductor equipment, and particularly relates to an integrated horizontal silicon carbide boat and a preparation method thereof. The preparation method comprises the following steps: mixing and ball-milling a grouting system mixture and silicon carbide powder with different granularities to obtain slurry, then pouring to obtain a silicon carbide boat biscuit, and finally carrying out the procedures of glue discharging, dipping, reactive sintering and the like to obtain a silicon carbide boat product. By adjusting the slurry composition and preparation process parameters, integrated preparation of the silicon carbide boat is realized, and the performance of the silicon carbide boat product is improved. According to the preparation method disclosed by the invention, during reactive sintering, a mode of coating Si3N4 is adopted to replace traditional BN permeation prevention, so that introduction of a B impurity is avoided. When the slurry is prepared, four stages of particles are proportioned, and the high-solid-content slurry is prepared by closely packing the particles. The preparation method disclosed by the invention is simple in process and short in preparation period, and introduction of impurities in a multi-process process is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision ceramic components for semiconductor equipment, specifically relates to the technical field of gel injection molding and reaction sintering, and in particular relates to an integrated horizontal silicon carbide crystal boat and a preparation method thereof. Background Art

[0002] The wafer boat is a transmission and carrying tool for wafer heat treatment and diffusion process, and is a key component of semiconductor device manufacturing equipment. The Chinese patent with the authorization announcement number CN209418474U discloses an integrated silicon boat, and points out that the wafer boat needs to withstand temperatures above 1000°C during heat treatment and diffusion; at the same time, it needs to carry a certain number of wafers and cannot contaminate the wafers. This requires the wafer boat to have not only high heat resistance, but also high load softening temperature and high purity. Traditional wafer boats use quartz glass products, which have poor temperature resistance, low load softening point (1100°C will cause deformation), easy to bond with wafers, and impurities such as potassium and sodium in glass products volatilize and easily contaminate wafers. With the increase in wafer size and the application of silicon carbide wafer materials with a higher specific gravity, the problems of quartz boats have become increasingly prominent, and quartz glass materials can no longer meet the development needs of chip manufacturing processes.

[0003] In foreign countries, silicon carbide boats with high purity, high thermal conductivity, similar thermal expansion coefficient to wafers, and high dimensional accuracy at high temperatures have been fully adopted in the heat treatment of wafers and doping diffusion carriers. The Chinese patent with publication number CN115466123A discloses a silicon carbide ceramic and its preparation method and application, which adopts isostatic pressing combined with reaction sintering to prepare silicon carbide boats: because the boat is a special-shaped part, isostatic pressing integrated molding is difficult to implement. If it is simply molded, the later processing is extremely complicated, time-consuming and labor-intensive, and extremely high requirements are placed on the processing equipment and process; secondly, this method requires solidification, sintering, purification, multiple impregnation and sintering after isostatic pressing, and the process is complicated and has no operability; the purification temperature is as high as 2450°C, which is the recrystallization sintering temperature of silicon carbide, which is out of the scope of reaction sintering; and the production cycle is long (more than 20 days) and the cost is high.

[0004] Therefore, in order to solve the above problems, in view of the small and thin characteristics of the horizontal wafer boat, the present invention proposes an integrated preparation method of the horizontal silicon carbide wafer boat, aiming to provide direct guidance for engineering mass production. Summary of the invention

[0005] In order to solve the problems of heat resistance, low load softening temperature, wafer contamination of existing quartz crystal boats and the complex process problem in patent CN115466123A, the present invention provides an integrated horizontal silicon carbide crystal boat and a preparation method thereof, which realizes the integrated preparation of silicon carbide crystal boats by adjusting the slurry composition and the preparation process parameters, and improves the performance of silicon carbide crystal boat products.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing an integrated horizontal silicon carbide wafer boat comprises the following steps: (1) Weighing each component in the grouting system and mixing them evenly to obtain a grouting system mixture; (2) Weighing composite silicon carbide powder and adding it to the grouting system mixture of step (1), mixing evenly to obtain a first slurry, and ball milling to obtain a second slurry; (3) Assembling the wafer boat mold, sieving, defoaming, and initiating the second slurry, vacuum-injecting it into the wafer boat mold, letting it stand, demolding, and drying it to obtain a silicon carbide wafer boat blank; (4) Debinding and dipping the dried silicon carbide wafer boat blank, then coating the lower surface and / or upper surface of the silicon carbide wafer boat blank with Si3N4 suspension or Si3N4 paste, and reacting and sintering to obtain a silicon carbide wafer boat; (5) Post-processing the silicon carbide wafer boat in step (4) to obtain a final product.

[0007] Furthermore, in step (1), the grouting system used is a water-based acrylamide system, including cross-linking system components and additives.

[0008] Further preferably, the monomer in the cross-linking system components is acrylamide, the cross-linking agent is methylene bisacrylamide, and the additives include an inhibitor and a dispersant.

[0009] More preferably, the dispersant is at least one of n-butanol, tetramethylammonium hydroxide, polyethylene glycol, dimethylformamide, and cyclohexanol.

[0010] More preferably, the polymerization inhibitor is at least one of tert-butylcatechol (phenols), tetrachlorobenzoquinone (quinones), thiodiphenylamine, and nitrobenzene (aromatic nitro compound).

[0011] Preferably, when the polymerization inhibitor is a combination of thiodiphenylamine and tert-butylcatechol, the mass ratio of thiodiphenylamine to tert-butylcatechol is 1:(2-4).

[0012] More preferably, the additive also includes a plasticizer.

[0013] More preferably, the plasticizer is at least one of glycerol and isopropyl alcohol.

[0014] Furthermore, in step (1), the ball milling time is 4 to 6 hours.

[0015] Furthermore, the composite silicon carbide powder of step (2) is composed of silicon carbide particles of different particle sizes.

[0016] Preferably, the composite silicon carbide powder is composed of four silicon carbide powder gradations of particle sizes, wherein the silicon carbide powder particles of the four particle sizes account for 40~45wt%, 25~30wt%, 20~25wt%, and 5~10wt%; the median particle sizes of the silicon carbide powders of the four particle sizes are 45-55μm, 10-20μm, 1-5μm, and 0-0.5μm, respectively; in order to increase the solid content of the slurry, the silicon carbide powder used is spherical, and the sphericity of the silicon carbide powder particles is greater than 0.8; the purity of the silicon carbide powder is ≥99.9%.

[0017] Furthermore, the second slurry in step (2) comprises monomers, cross-linking agents, composite silicon carbide powder, additives and water; the proportions of the components are as follows: monomers 2-5wt%, cross-linking agents 0.2-0.5wt%, composite silicon carbide powder 80-88wt%, additives 0.5-2wt%, and the balance water.

[0018] Furthermore, in step (2), the solid content of the second slurry is 62 vt%-70 vt%, the viscosity of the second slurry is (0.5-6) ​​Pa·s, and the pH value of the second slurry is 12-15; preferably, the volume solid content of the second slurry is 68 vt%-70 vt%, wherein when the solid content is 70 vt%, the viscosity is 6 Pa·s and the pH value is 13.9.

[0019] Furthermore, in step (3), the wafer boat mold is composed of multiple parts, including a base, an upper cover plate, a front side plate, a rear side plate and two plug rods; The top of the base is provided with a lower groove, which runs through the front and rear ends of the base; the bottom of the lower groove is provided with a plurality of protrusions for forming an opening for the silicon carbide wafer boat blank; A boss is provided at the bottom end of the upper cover plate at a position corresponding to the notch of the lower groove, and the boss extends along the extension direction of the upper cover plate; the space between the boss and the lower groove is used to form a silicon carbide crystal boat.

[0020] Furthermore, the front side plate is arranged at the front end of the base, and the rear side plate is arranged at the rear end of the base.

[0021] Furthermore, the front side panels and the rear side panels are arranged in such a manner that threaded holes or pin holes are provided on the front and rear ends of the front side panels, the rear side panels and the base, and the front side panels are placed at the front end of the base and the rear side panels are placed at the rear end of the base, and then the bolts are sequentially passed through the threaded holes of the front side panels and the front end of the base, and the bolts are sequentially passed through the threaded holes of the rear side panels and the rear end of the base; or the pins are sequentially passed through the pin holes of the front side panels and the front end of the base, and the pins are sequentially passed through the pin holes of the rear side panels and the rear end of the base, thereby fixing the front side panels to the front end of the base and fixing the rear side panels to the rear end of the base.

[0022] Furthermore, the front side plate is provided with two front through holes for the insertion rod to pass through; and the rear side plate is provided with two rear through holes for the insertion rod to pass through.

[0023] Specifically, when the wafer boat mold is in use, the base is placed on a horizontal plane or a processing machine, with the notch of the lower groove facing upward, and the front side plate is fixed to the front end of the base and the rear side plate is fixed to the rear end of the base according to the above method; Then insert the two plugs into the front holes of the front side plate respectively, and then pass through the lower groove and out from the two rear holes of the rear side plate; Then inject the slurry into the wafer boat mold, and then adjust the boss at the bottom of the upper cover plate to the position of the lower groove notch, and cover the upper cover plate on the top of the base, and finally fix the upper cover plate and the base to complete the assembly of the wafer boat mold.

[0024] Furthermore, the wafer boat mold of the present invention is easy to assemble during use and can be disassembled after the slurry is solidified for easy demoulding; the structural design of this mold can solve the problem that the three-axis machine tool cannot process the groove of the blank.

[0025] Furthermore, in step (3), the main material of the wafer boat mold is stainless steel. When in use, the surface may be coated with organic matter, and the organic matter includes but is not limited to polytetrafluoroethylene, acrylic resin, or epoxy resin.

[0026] Furthermore, in step (3), the initiator used is an aqueous solution of ammonium persulfate, the amount used is (0.1-0.8) wt% of the second slurry, and the concentration of the aqueous solution of ammonium persulfate is 20 wt%-60 wt%.

[0027] Furthermore, in step (3), the vacuum degree during vacuum injection is ≤-0.08 MPa.

[0028] Furthermore, in step (3), in order to facilitate demoulding of the special-shaped part, a mold release agent is applied to the surface of the mold before grouting, which is a grease-based hydrophobic organic substance; specifically, one or both of ordinary lubricating oil and paraffin oil.

[0029] Further preferably, the debinding in step (4) is high-temperature debinding, specifically, pre-sintering at a temperature of 1700° C. to 1800° C. for 0.5 h to 2 h in a C-rich environment in a vacuum furnace (the C-rich environment is achieved by using instruments such as electrodes, crucibles, and graphite powder padding, which is a conventional prior art and is not the inventive point of the present invention, so it will not be described in detail), that is, debinding is performed in a high-temperature manner; in addition, a low-temperature debinding method can also be used.

[0030] Alternatively, as another implementation, in step (4), the crystal boat blank after drying in step (3) may be directly covered with Si powder (particle size <1 mm) on the lower surface of the crystal boat blank without undergoing high-temperature debinding, and Si3N4 suspension or Si3N4 paste may be coated on the upper surface of the crystal boat to prevent seepage, and then the debinding and sintering integrated process may be used for treatment.

[0031] Furthermore, the "impregnation" process in step (4) can be a conventional process in the prior art, and is not the inventive point of the present invention, so it will not be described in detail; in addition, the "impregnation" process may not be used.

[0032] Furthermore, the coating method in step (4) is to apply Si3N4 suspension or Si3N4 paste on the lower surface of the silicon carbide crystal boat blank, place Si blocks or Si particles on the upper surface of the silicon carbide crystal boat blank, and apply Si3N4 suspension or Si3N4 paste at the position on the upper surface of the silicon carbide crystal boat blank where no Si blocks or Si particles are placed.

[0033] Specifically, in each silicon carbide wafer boat blank, 10-40 wt % of the mass of the silicon carbide wafer boat blank is used as silicon chunks, or 10-50 wt % of the mass of the silicon carbide wafer boat blank is used as silicon powder.

[0034] Alternatively, as another embodiment, the coating method in step (4) is to lay a sufficient amount of Si blocks or Si particles on the lower surface of the silicon carbide crystal boat blank, and apply Si3N4 suspension or Si3N4 paste on the upper surface of the silicon carbide crystal boat blank.

[0035] Furthermore, the coating method in step (4) is spraying or brushing.

[0036] Furthermore, in step (4), the concentration of the Si3N4 suspension or Si3N4 paste is 10-40wt%; the Si3N4 suspension or Si3N4 paste can be prepared using anhydrous ethanol and / or deionized water as a solvent; in addition, n-butanol with a mass fraction of 1-3% of the suspension or paste can be added to the Si3N4 suspension or Si3N4 paste to disperse the Si3N4 in the suspension or paste, wherein the Si3N4 particle size is below 100μm.

[0037] Furthermore, in step (4), during the reaction sintering, the principle of liquid silicon infiltration (LSI) is utilized to prevent infiltration by coating Si3N4 suspension or Si3N4 paste on the surface of the green blank, and a silicon infiltration channel is reserved.

[0038] Furthermore, in step (4), the reaction sintering temperature is 1400°C to 1500°C, the sintering time is 0.5 to 2 hours, and the gas pressure is 10 to 50 Pa.

[0039] Furthermore, the post-processing in step (5) includes surface processing, and the surface processing includes sandblasting and grooving on the wafer boat, and the grooving is processed by diamond wire cutting.

[0040] Furthermore, based on a general inventive concept, the present invention also provides an integrated horizontal silicon carbide wafer boat prepared by the above method.

[0041] The silicon carbide crystal boat prepared by the present invention has a density of 3.01-3.05 g / cm 3 The purity can reach 99.9%, the thermal conductivity is 120 W / m·K, the room temperature thermal expansion coefficient is 2.5 ppm / K, and after testing, the 12 specifications are 3×4×40mm 3 The average flexural strength of the sample is 353.7MPa, it does not crack when quenched at 300℃, and the maximum operating temperature is 1300℃, showing good performance.

[0042] Furthermore, based on a general inventive concept, the present invention also provides the use of the integrated horizontal silicon carbide wafer boat as a transmission and carrying tool for wafer heat treatment and diffusion processes.

[0043] The silicon carbide wafer boat prepared by the present invention can be used as a transmission and carrying tool for wafer heat treatment and diffusion processes. With the advancement of the research and development of the third-generation semiconductor and the requirement for chip stability, the wafer heat treatment temperature is also gradually increasing (1000°C→1300°C). In addition, the high-temperature annealing of the wafer requires that the metal impurity content in the atmosphere is as low as possible. Compared with the quartz boat, the silicon carbide wafer boat has obvious advantages in purity, heat resistance, and no deformation under heat.

[0044] Compared with the prior art, the present invention has the following beneficial effects: 1. During the reaction sintering, the preparation method of the present invention adopts the method of coating Si3N4 to replace the traditional BN barrier, thereby avoiding the introduction of B impurities; the preparation method of the present invention has the characteristics of low cost, simple principle and easy operation.

[0045] 2. The slurry of the present invention adopts a four-level particle ratio during preparation, and a slurry with a high solid content is prepared by densely packing the particles.

[0046] 3. The present invention adopts an integrally formed detachable mold assembly, which is convenient for grouting and disassembly, and avoids the problem that the three-axis machine tool cannot process the groove; at the same time, the mold surface is sprayed with organic matter to avoid the introduction of metal impurities.

[0047] 4. The preparation method of the present invention has simple procedures and a short preparation cycle (<10 days), which avoids the introduction of impurities in multiple process steps. At the same time, it can also save production costs and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A front view showing the disassembly of the base and the upper cover plate in the wafer boat mold; Figure 2 A top view of the base in the wafer boat mold; Figure 3 A top view of the upper cover plate in the wafer boat mold; Figure 4 is a front view of the front side plate in the wafer boat mold; Figure 5 A top view of the insert rod in the wafer boat mold; Figure 6 The following is a disassembled photo of the crystal boat mold; Figure 7 A schematic diagram of the coating method of step (4) in Example 1; Figure 8 This is a photo of the silicon carbide wafer boat prepared in Example 1. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0050] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation and specific embodiments of the present invention; however, this is not the only form of implementing or using the specific embodiments of the present invention. The implementation covers the features of multiple specific embodiments and the method steps and sequences used to construct and operate these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences.

[0051] Unless otherwise specified, the instruments and equipment used in the following examples are all commercially available conventional instruments and equipment; other reagents and materials used are all commercially available conventional reagents and materials unless otherwise specified.

[0052] Example 1 Example 1 provides a method for preparing an integrated horizontal silicon carbide wafer boat, and the specific steps are as follows: (1) First, weigh the grouting system mixture; the grouting system used is a water-based acrylamide system, including a cross-linking system component, a dispersant, an inhibitor and a plasticizer; In this embodiment, the monomer in the cross-linking system components is acrylamide, the cross-linking agent is methylene bisacrylamide; the dispersant is n-butanol, tetramethylammonium hydroxide and polyethylene glycol, the plasticizer is glycerol, and the inhibitor is tetrachlorobenzoquinone; The specific steps are: weighing acrylamide (monomer), methylene bisacrylamide (cross-linking agent, methylene bisacrylamide, also called N,N'-methylene bisacrylamide, referred to as MBA), deionized water, n-butanol (dispersant), tetramethyl ammonium hydroxide (dispersant), polyethylene glycol (dispersant), glycerol (plasticizer), tetrachlorobenzoquinone (inhibitor) in turn and mixing them evenly to obtain a grouting system mixture; (2) Weighing silicon carbide powders with particle sizes of 55 μm, 20 μm, 5 μm and 0.5 μm in a mass ratio of 40:30:20:10 respectively to obtain composite silicon carbide powder, and adding them to the grouting system mixture of step (1), mixing them evenly to obtain a first slurry; the sphericity of the silicon carbide powders weighed above is 0.86 and the purity is 99.9%; adding grinding balls to the first slurry and milling for 5 hours to obtain a second slurry, in which the proportions of the components of the second slurry are as follows: 2 wt% monomer, 0.2 wt% cross-linking agent, 88 wt% composite silicon carbide powder, 2 wt% dispersant, inhibitor and plasticizer, and the balance is water; the second slurry has a solid content of 68 vt% and a viscosity of 4.6 Pa·s; (3) Figure 1-5 The wafer boat mold shown in the figure is assembled, the second slurry is sieved for defoaming, initiated (using an aqueous solution of ammonium persulfate with a concentration of 40wt% as an initiator, and the amount added is 0.4wt% of the second slurry), and vacuum injected into the wafer boat mold (the vacuum degree is ≤-0.08MPa), and after standing for 60min, demoulding and drying are performed to obtain a silicon carbide wafer boat blank; to facilitate the demoulding of special-shaped parts, a mold release agent is applied to the surface of the mold before grouting, and the mold release agent is an ordinary lubricating oil (ordinary lubricating oils on the market can be used, which is not limited here. The ZK-100 high-speed vacuum pump oil produced by Beijing Gonghua Special Oil Products Co., Ltd. is used in this embodiment); Specifically, Figure 1-5 As shown, in step (3), the wafer boat mold is composed of multiple parts, including a base 1, an upper cover plate 2, a front side plate 3, a rear side plate (the structure is the same as the front side plate 3, not marked in the figure) and two plug rods 5; The top of the base 1 is provided with a lower groove 11, which runs through the front and rear ends of the base 1; the bottom of the lower groove 11 is provided with a plurality of protrusions 12 for forming an opening for the silicon carbide wafer boat blank; A boss 21 is provided at the bottom end of the upper cover plate 2 at a position corresponding to the notch of the lower groove 11, and the boss 21 extends along the extension direction of the upper cover plate 2; the space between the boss 21 and the lower groove 11 is used to form a silicon carbide wafer boat; The front side plate 3 is arranged at the front end of the base 1, and the rear side plate is arranged at the rear end of the base 1; The specific setting method is that the front side plate 3, the rear side plate and the front and rear ends of the base 1 are all provided with threaded holes or latch holes, and the front side plate 3 is placed at the front end of the base 1, and the rear side plate is placed at the rear end of the base 1, and then the bolts are sequentially passed through the threaded holes at the front end of the front side plate 3 and the base 1, and the bolts are sequentially passed through the threaded holes at the rear end of the rear side plate and the base 1; or the latches are sequentially passed through the latch holes at the front end of the front side plate 3 and the base 1, and the latches are sequentially passed through the latch holes at the rear end of the rear side plate and the base 1, so as to fix the front side plate 3 to the front end of the base 1 and the rear side plate to the rear end of the base 1; The front side plate 3 is provided with two front through holes 31 for the insertion rod 5 to pass through; the rear side plate is provided with two rear through holes for the insertion rod 5 to pass through; When the wafer boat mold is in use, the base 1 is placed on a horizontal plane or a processing machine, with the notch of the lower groove 11 facing upwards, and the front side plate 3 is fixed to the front end of the base 1 and the rear side plate is fixed to the rear end of the base 1 according to the above method; Then, the two insert rods 5 are respectively inserted into the front through holes 31 of the front side plate 3, and penetrate through the lower groove 11, and then pass out from the two rear through holes of the rear side plate; Then, the slurry is injected into the wafer boat mold, and the boss 21 at the bottom end of the upper cover plate 2 is aligned with the position of the lower groove notch, and the upper cover plate 2 is covered on the top of the base 1, and finally the upper cover plate 2 and the base 1 are fixed, thus completing the assembly of the wafer boat mold; The wafer boat mold of the present invention is easy to assemble when in use, and can be disassembled after the slurry is solidified, so as to facilitate demoulding; the structural design of the mold can solve the problem that the three-axis machine tool cannot process the groove of the blank; In step (3), the main material of the wafer boat mold is stainless steel, and when in use, an organic coating (specifically polytetrafluoroethylene) may be performed on the surface; Specifically, the disassembled photos of the crystal boat mold are as follows: Figure 6 As shown; (4) The dried green blank is debonded and impregnated. The green blank is laid on graphite paper and a layer of Si3N4 suspension (30wt%) is coated on its lower surface with a coating thickness of about 0.1~0.3mm. A pressureless sintered SiC block of just the right height is used to support the concave part of the green blank to prevent deformation of the green blank during subsequent reaction sintering. Then, a sufficient amount of small Si blocks (about 2cm in size) are weighed and placed on top of the green blank (40wt% of the weight of the crystal boat is used for each wafer boat, or 50wt% of the weight of the crystal boat is used for silicon powder). After the placement is completed, the remaining positions not in contact with Si are coated with a 30wt% Si3N4 suspension (coating thickness of about 0.1~0.3mm) to prevent penetration. The median particle size of Si3N4 is 25μm, and the coating method is brush coating. The coating pattern of step (4) is shown in the figure below. Figure 7 As shown; Then, the reaction was sintered at a temperature of 1500°C and a pressure of 10Pa for 0.5h to obtain a product with a purity of 99.9% and a density of 3.04g / cm 3 Silicon carbide wafer boats, such as Figure 8 As shown; The debinding in step (4) is high-temperature debinding, specifically, pre-sintering at 1750° C. for 1 h in a C-rich environment in a vacuum furnace (the C-rich environment is achieved by using instruments such as electrodes, crucibles, and graphite powder padding, which is a conventional prior art and not the inventive point of the present invention, so it will not be described in detail) to discharge organic matter and remove impurities from some metals; and utilizing the principle of metal saturated vapor pressure, that is, the boiling point is reduced under high vacuum, so that metal impurities are gasified and eliminated; (5) The silicon carbide wafer boat is sandblasted and polished, and finally the wafer support grooves on the wafer boat are cut using diamond wire cutting to obtain the final product.

[0053] The silicon carbide wafer boat prepared in this embodiment has a density of 3.04 g / cm 3 , purity reaches 99.9%, thermal conductivity 120 W / m·K, room temperature thermal expansion coefficient 2.5 ppm / K, after testing, 12 specifications are 3×4×40mm 3 The average flexural strength of the sample is 353.7MPa, it does not crack when quenched at 300℃, and its maximum operating temperature is 1300℃. It can be used as a carrier and transport tool for wafers in the semiconductor manufacturing process.

[0054] Example 2 Example 2 provides a method for preparing an integrated horizontal silicon carbide wafer boat. The preparation method of Example 2 is different from that of Example 1 in that: In step (1), the water-based acrylamide system includes a cross-linking system component, an inhibitor and a dispersant; In this embodiment, the monomer in the cross-linking system components is acrylamide, the cross-linking agent is methylenebisacrylamide; the dispersant is tetramethylammonium hydroxide; the inhibitor is thiodiphenylamine and tert-butylcatechol, and the mass ratio of the two is 1:3. In this embodiment, the amount of the inhibitor is one forty thousandth of the mass of the second slurry; The specific steps are: weighing monomers, cross-linking agent, deionized water, dispersant, and polymerization inhibitor in sequence, mixing them evenly, and obtaining a grouting system mixture; Step (2) specifically comprises: weighing silicon carbide powders with particle sizes of 45 μm, 10 μm, 1 μm and 0.3 μm respectively according to a mass ratio of 45:30:20:5 to obtain composite silicon carbide powder, and adding the powders to the grouting system mixture in step (1), mixing them evenly to obtain a first slurry, wherein the sphericity of the silicon carbide powders weighed above is 0.94 and the purity is 99.9%; adding grinding balls to the first slurry and milling for 6 hours to obtain a second slurry; in the second slurry, the proportion of each component is 5wt% of the monomer, 0.5wt% of the cross-linking agent, 80wt% of the composite silicon carbide powder, 0.5wt% of the dispersant and the inhibitor (the mass ratio of the two is 249:1), and the balance is water; the second slurry has a solid content of 70vt% and a viscosity of 6Pa·s; In step (3), the release agent is paraffin oil; Step (4) specifically comprises: laying a sufficient amount of Si powder (particle size <1 mm) on the lower surface of the dried wafer boat blank, and coating the upper surface of the wafer boat with a 30wt% Si3N4 suspension (coating thickness of about 0.1-0.3 mm) to prevent penetration, wherein the median particle size of Si3N4 is 10 μm, and the coating method is spraying; Then, the debinding and sintering integrated process was used for 2 h at a temperature of 1500 °C and a pressure of 50 Pa to obtain a 99.9% purity and a density of 3.01 g / cm 3 Silicon carbide wafer boat; Step (5) specifically includes sandblasting the silicon carbide wafer boat to fine-process the surface, and then using diamond wire cutting to groove the wafer support grooves on the wafer boat to obtain the final product.

[0055] The results of the tests show that the performance of the sample in Example 2 is substantially the same as that of Example 1.

[0056] The above embodiments are examples of the implementation methods of the present invention, and the implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing an integrated horizontal silicon carbide wafer boat, characterized in that: The steps include: (1) Weighing the components of the grouting system and mixing them evenly to obtain a grouting system mixture; (2) Weighing composite silicon carbide powder and adding it to the grouting system mixture of step (1), mixing evenly to obtain a first slurry, and ball milling to obtain a second slurry; (3) Assembling the wafer boat mold, sieving, defoaming, and initiating the second slurry, vacuum-injecting it into the wafer boat mold, letting it stand, demolding, and drying it to obtain a silicon carbide wafer boat blank; (4) Debinding and dipping the dried silicon carbide wafer boat blank, then coating the lower surface and / or upper surface of the silicon carbide wafer boat blank with Si3N4 suspension or Si3N4 paste, and reacting and sintering to obtain a silicon carbide wafer boat; (5) Post-processing the silicon carbide wafer boat in step (4) to obtain a final product.

2. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: The grouting system used in step (1) is a water-based acrylamide system, comprising a cross-linking system component and an additive; the monomer in the cross-linking system component is acrylamide, and the cross-linking agent is methylene bisacrylamide; the additive comprises an inhibitor and a dispersant; the dispersant is at least one of n-butanol, tetramethylammonium hydroxide, polyethylene glycol, dimethylformamide, and cyclohexanol; the inhibitor is at least one of tert-butylcatechol, tetrachlorobenzoquinone, thiodiphenylamine, and nitrobenzene.

3. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 2, characterized in that: The additives also include a plasticizer; the plasticizer is at least one of glycerol and isopropyl alcohol.

4. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: The composite silicon carbide powder in step (2) is composed of four kinds of silicon carbide powder gradations, wherein the proportions of the four kinds of silicon carbide powder particles are 40-45wt%, 25-30wt%, 20-25wt%, and 5-10wt%; the median particle sizes of the four kinds of silicon carbide powder are 45-55μm, 10-20μm, 1-5μm, and 0-0.5μm, respectively; the silicon carbide powder used is spherical, and the sphericity of the silicon carbide powder particles is greater than 0.8; the purity of the silicon carbide powder is ≥99.9%.

5. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: Step (2) The second slurry comprises monomers, cross-linking agents, composite silicon carbide powder, additives and water; the proportions of the components are as follows: monomers 2-5wt%, cross-linking agents 0.2-0.5wt%, composite silicon carbide powder 80-88wt%, additives 0.5-2wt%, and the balance water.

6. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: The solid content of the second slurry is 62 vt %-70 vt %, the viscosity of the second slurry is (0.5-6) ​​Pa·s, and the pH value of the second slurry is 12-15.

7. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: In step (3), the wafer boat mold is composed of multiple parts, including a base, an upper cover plate, a front side plate, a rear side plate and two plug rods; The top of the base is provided with a lower groove, which runs through the front and rear ends of the base; the bottom of the lower groove is provided with a plurality of protrusions for forming an opening for the silicon carbide wafer boat blank; A boss is provided at the bottom end of the upper cover plate at a position corresponding to the notch of the lower groove, and the boss extends along the extension direction of the upper cover plate; the space between the boss and the lower groove is used to form a silicon carbide crystal boat; The front side plate is arranged at the front end of the base, and the rear side plate is arranged at the rear end of the base; The front side plate is provided with two front through holes for inserting rods to pass through; the rear side plate is provided with two rear through holes for inserting rods to pass through.

8. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: The coating method in step (4) is to apply Si3N4 suspension or Si3N4 paste on the lower surface of the silicon carbide wafer boat blank, place Si blocks or Si particles on the upper surface of the silicon carbide wafer boat blank, and apply Si3N4 suspension or Si3N4 paste on the position on the upper surface of the silicon carbide wafer boat blank where no Si blocks or Si particles are placed; Alternatively, the coating method in step (4) is to lay a sufficient amount of Si blocks or Si particles on the lower surface of the silicon carbide wafer boat blank, and apply Si3N4 suspension or Si3N4 paste on the upper surface of the silicon carbide wafer boat blank.

9. The method for preparing an integrated horizontal silicon carbide wafer boat according to claim 1, characterized in that: In step (4), the reaction sintering temperature is 1400°C~1500°C, the sintering time is 0.5~2h, and the gas pressure is 10~50Pa.

10. An integrated horizontal silicon carbide wafer boat prepared by the method according to any one of claims 1 to 9.

Images