Device and method for preparing large-size high-quality graphene wafers in batches

Abstract

The invention discloses a device and a method for preparing large-size high-quality graphene wafers in batches. The device comprises a quartz tube, a heating assembly and a wafer carrier, the heating assembly is matched with a graphite cylinder heating body through an intermediate frequency coil, the graphite cylinder heating body is located in the quartz tube, and the intermediate frequency coil is located outside the quartz tube, is flush with the graphite cylinder heating body and is used for inductively heating the graphite cylinder heating body; the wafer carrier is provided with a plurality of limiting parts which are used for limiting the positions of the plurality of wafers.

Description

Technical Field

[0001] The present invention belongs to the technical field of graphene preparation, and in particular relates to a device and method for batch preparing large-size high-quality graphene wafers. Background Art

[0002] As a unique two-dimensional material, graphene has excellent carrier mobility, electrical conductivity, thermal conductivity and mechanical strength, and is also flexible, transparent, chemically stable and lightweight. This makes graphene have broad application prospects in many fields such as electronic devices, sensors, strength materials, flexible electronics, and optical devices. Its advantages such as optical properties, high electrical conductivity and high thermal conductivity make graphene one of the materials that has attracted much attention in scientific research and industrial applications.

[0003] Graphene has high carrier mobility, which is dozens of times higher than commercial silicon wafers, and shows low sensitivity to temperature and doping effects. In the field of ultra-high frequency electronic devices, graphene crystals show important application value. However, the improvement of the performance of graphene electronic devices is subject to the quality of graphene, which directly depends on the improvement of preparation technology.

[0004] At present, there are two main types of methods commonly used to prepare graphene single crystals, one is chemical vapor deposition (CVD) method, and the other is high-temperature SiC thermal decomposition method. The CVD method is relatively simple and low-cost, but the preparation of graphene crystals usually relies on metal substrates such as Cu, Ni or Pt, and the prepared graphene crystals need to be peeled off and transferred to various insulating substrates for standby. In the process of peeling and transfer, it is easy to damage or contaminate the graphene, which is not conducive to the subsequent preparation and performance improvement of electronic devices. Sometimes metals are used as remote or short-range catalysts to grow large areas of graphene on insulating substrates, but metal residues are often unavoidable. The high-temperature SiC thermal decomposition method uses high temperature to separate Si atoms on the SiC surface from the SiC substrate to obtain one or several layers of graphene. Its production process can be integrated with the current semiconductor process, and it is expected to be made into devices without the need for subsequent processes such as transfer. However, due to the limitation of growth mechanism, the uniformity of graphene obtained by SiC pyrolysis is poor, and it is difficult to obtain a graphene film with controllable number of layers. In addition, there is an obvious buffer layer between the graphene prepared by SiC pyrolysis and the SiC substrate, which reduces the mobility of graphene and is not conducive to the application of graphene electronic devices. At the same time, the high production cost and harsh preparation conditions restrict the wider use of SiC epitaxial growth graphene in practical applications. The CVD method has become the fastest-growing and most promising mainstream preparation method due to its low cost, easy large-scale production, and compatibility with semiconductor processes. The CVD method uses catalytic growth of graphene on transition metals and cannot be directly applied to the preparation of electronic devices. The graphene needs to be transferred to the dielectric layer to effectively assemble the device. Therefore, it is necessary to study the direct use of CVD method to grow graphene on a dielectric substrate, which can simplify the preparation process and provide greater flexibility for exploring new applications and adapting to specific needs. The batch preparation of graphene can not only reduce costs and improve production efficiency, but also help promote technological innovation and expand the application of graphene in different fields. These advantages make graphene more competitive and sustainable in actual industries.

[0005] CN 103172061 A discloses a method for growing large-area graphene on an insulating substrate. The method uses an insulating material as a growth substrate, copper foil as a catalyst, carbon source, hydrogen and protective gas as gas sources, and a two-step (low-pressure growth and high-pressure growth) chemical vapor deposition method. Through the face-to-face contact between the insulating substrate and the copper foil, a large-area graphene is grown on the insulating substrate using the short-range catalytic effect of the copper foil. The whole process of the method of the invention is simple to operate, low in cost, and has high repeatability in sample preparation and little external interference. The prepared single-layer graphene can be made into a large-scale circuit device using an exposure method without a cumbersome transfer process.

[0006] CN 114804082B provides a step-controlled graphene sapphire wafer and a preparation method thereof. The preparation method comprises: pre-treating the sapphire wafer; placing the pre-treated sapphire wafer substrate in a graphite plate, heating it by electromagnetic induction, pumping the pressure to 10Pa, setting the growth pressure, growth temperature and growth time; introducing argon when the temperature rises to 200-500°C, introducing hydrogen when the temperature continues to rise to 600°C-800°C; introducing growth gas when the temperature rises to the growth temperature; after the growth is completed, stop introducing growth gas, cool down in an argon and hydrogen environment, turn off hydrogen when the temperature is lower than 500°C, turn off argon when the temperature is lower than 100°C, perform vacuum breaking treatment, and obtain a graphene sapphire wafer. High-quality graphene sapphire wafers can be prepared by the above method.

[0007] CN 216808956U discloses a heating furnace and a CVD reaction device, wherein the heating furnace comprises a quartz tube and an electric heating assembly, wherein the quartz tube has a chamber inside; the electric heating assembly comprises a coil, a power supply and a graphite disk, wherein the coil is electrically connected to the power supply and the coil is spirally wound around the outer periphery of the quartz tube, and is used to generate a magnetic field in the chamber after power is turned on; the graphite disk is configured to be able to enter and exit the chamber, and can be arranged corresponding to the coil, and is used to generate heat under the action of the magnetic field; the graphite disk is used to support a wafer substrate, and one side surface of the wafer substrate is used to grow graphene. By increasing the heating temperature, it is helpful to obtain higher quality graphene, and the direct preparation of high quality graphene film on the wafer substrate can be realized. Summary of the invention

[0008] In order to solve the problems in the prior art, the present invention provides a device for batch preparation of graphene wafers, the device comprising:

[0009] case;

[0010] A reaction chamber, the reaction chamber is located in the middle of the shell, and is composed of a graphite tube heating element and a wafer carrier placed inside the graphite tube heating element;

[0011] An intermediate frequency coil, the intermediate frequency coil is located outside the housing, the intermediate frequency coil is flush with the graphite tube heating element, and is used for inductively heating the graphite tube heating element;

[0012] Among them, a plurality of limiting components are arranged on the wafer carrier to limit the positions of the plurality of wafers.

[0013] According to a specific embodiment of the present invention, a gas preheating graphite disk is arranged above the graphite cylinder heating element, and a gas uniforming disk is arranged above the preheating graphite disk.

[0014] According to a specific embodiment of the present invention, the gas distributor is arranged directly above the wafer. The gas distributor is provided with through holes which are vertically arranged and have an inner diameter of 1 - 3 mm, and are used to evenly distribute gas into the reaction cavity, making the reaction more uniform. Preferably, the gas distributor is a quartz gas distributor.

[0015] According to a specific embodiment of the present invention, the quartz gas distributor adopts any one of the following two arrangement methods:

[0016] (1) Rectangular array arrangement: Set n rows of parallel through holes, 20 ≤ n ≤ 50. Keep the diameter of the through holes d1 unchanged. Set a through hole with a diameter of d1 centered on the center of the gas distributor. With this through hole as the center, arrange through holes with a diameter of d1 in a rectangular array, and the adjacent hole diameter interval is d2, 1 ≤ d1 ≤ 3 mm, d1 < d2 ≤ 6 mm;

[0017] (2) Circular array arrangement: Set i circles of concentric through holes, 3 ≤ i ≤ 20. Keep the diameter of the through holes d1 unchanged, 1 ≤ d1 ≤ 3 mm. Do not set a through hole at the center of the gas distributor. The distance between the center of the first circle of through holes and the center of the gas distributor is d2, and the difference in the radii of the concentric circles formed by the centers of the adjacent two circles of through holes is d2, d1 < d2 ≤ 6 mm; The included angle formed by the radial straight lines on the gas distribution plate where two adjacent gas distribution holes are located in the first circle is 45°; The included angle formed by the radial straight lines on the gas distribution plate where two adjacent gas distribution holes are located in the second circle is 30°; The included angle formed by the radial straight lines on the gas distribution plate where two adjacent gas distribution holes are located in the third circle is 20°; When 3 < i ≤ 20, the included angle formed by the radial straight lines on the spray plate where two adjacent spray holes are located in the i-th circle is 10°.

[0018] According to a specific embodiment of the present invention, a card slot is provided on the wafer carrier. By adjusting the distance between the card slots, the inter-chip distance of the wafer is adjusted, thereby adjusting the gas flow field distribution between the layers.

[0019] According to a specific embodiment of the present invention, from top to bottom, the distance between the card slots decreases.

[0020] According to a specific embodiment of the present invention, the material of the wafer carrier is alumina ceramic.

[0021] According to a specific embodiment of the present invention, the wafer carrier includes at least three columns. Among them, at least two columns are fixedly connected, and the columns are provided with card slots to support the wafer; at least one column is detachably connected to limit the position of the wafer.

[0022] According to a specific embodiment of the present invention, the housing is a sealed quartz tube.

[0023] Another object of the present invention is to provide a method for batch preparing high-quality graphene wafers on a sapphire wafer substrate, comprising using the above-mentioned device, comprising the following steps:

[0024] (1) Place the sapphire wafers into the wafer carrier one by one and fix them, raise the wafer to the middle of the intermediate frequency coil, and close the furnace door;

[0025] (2) Turn on the vacuum pump and set the growth pressure required for the reaction;

[0026] (3) Turn on the temperature control system, set the growth temperature and growth time required for the reaction, and set the heating rate in stages as follows: 25°C / min for the 20-500°C stage, 20°C / min for the 500-1000°C stage, 10°C / min for the 1000-1200°C stage, and 7.5°C / min from 1200°C to the growth temperature;

[0027] (4) Open the mass flow controller to introduce argon gas. When the temperature rises to 500°C, open the mass flow controller to introduce hydrogen gas.

[0028] (5) When the temperature rises to the set growth temperature, keep it warm for 10 min, and open the mass flow controller to introduce the carbon source gas;

[0029] (6) After the growth is completed, the heating system is turned off, the carbon source gas is turned off, and the temperature is lowered in an argon and hydrogen environment. When the temperature is lower than 500° C., the hydrogen is turned off;

[0030] (7) When the temperature is lower than 100° C., turn off the mass flow controller to turn off the argon gas, turn off the vacuum pump, perform vacuum breaking, lower the lifting platform, and obtain a graphene sapphire wafer.

[0031] Beneficial effects:

[0032] The present invention adopts a heating component that matches a medium frequency coil and a graphite tube heating element, and matches a wafer carrier with a layer spacing that decreases from top to bottom. The two work together to achieve batch preparation of high-quality graphene wafers on a sapphire wafer substrate. In addition, multiple graphene sapphire wafers can be grown simultaneously, and the growth efficiency of graphene can be improved.

[0033] The present invention arranges a gas preheating graphite disk above the graphite tube heating element, and an air uniforming disk is arranged above the preheating graphite disk. The carbon source gas is combed by the air uniforming disk to obtain a better flow field, and then preheated by the preheating graphite disk to improve the cracking rate and cracking uniformity of the carbon source, thereby ensuring the growth rate and uniformity of the graphene layer.

[0034] The device of the present invention combines direct growth technology with the needs of mass production, and directly grows a graphene layer on the surface of an insulating substrate without the need for a transfer step. Using advanced technologies such as chemical vapor deposition, the device can achieve high-quality, high-purity graphene growth on an insulating substrate. The present invention provides an efficient, stable and large-scale applicable method and device, which brings an important breakthrough in the field of graphene preparation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the device for batch preparation of graphene sapphire wafers of the present invention;

[0036] Figure 2 is a schematic diagram of the structure of the reaction chamber;

[0037] Figure 3 It is a diagram of a rectangular array through-hole quartz uniform gas disk;

[0038] Figure 4 It is a circular array through-hole quartz gas-distributing disk;

[0039] Figure 5 Simulation diagram of the flow field on the surface of the first wafer using the rectangular array gas homogenization device;

[0040] Figure 6 Simulation diagram of the flow field on the surface of the first wafer using the circular array gas homogenization device;

[0041] Figure 7 is a front view of the wafer carrier;

[0042] Figure 8 FIG. 4 is a top view of the wafer carrier.

[0043] Explanation of symbols:

[0044] 1. Upper stainless steel flange, 2. Insulation material, 3. Gas uniformizing plate, 4. Graphite tube heating element, 5. Medium frequency coil, 6. Shell, 7. Lower stainless steel flange, 8. Vacuum chamber, 9. Air outlet, 10. Lifting platform transfer rod, 11. Air inlet, 12. Thermocouple, 13. Gas preheating graphite plate, 14. Wafer carrier, 15. Several wafers, 16. Carrier crucible support, 17. Lifting platform. DETAILED DESCRIPTION

[0045] The present invention is described in detail below in conjunction with specific implementation modes.

[0046] The present invention provides a device for batch preparation of graphene wafers, please refer to Figure 1 and Figure 2 , the device comprises:

[0047] Shell 6;

[0048] A reaction chamber, which is located in the middle of the shell and consists of a graphite tube heating element 4 and a wafer carrier 14 placed inside the graphite tube heating element;

[0049] An intermediate frequency coil 5, the intermediate frequency coil 5 is located outside the housing 6, the intermediate frequency coil 5 is flush with the graphite tube heating element 4, and is used for inductively heating the graphite tube heating element 4;

[0050] The wafer carrier 14 is provided with a plurality of limiting components for limiting the positions of the plurality of wafers.

[0051] In the technical solution of the present invention, multiple pieces refer to ≥2 pieces, preferably 2-10 pieces.

[0052] In an optional embodiment, a gas preheating graphite disk 13 is arranged above the graphite tube heating element 4 , and a gas uniforming disk 3 is arranged above the preheating graphite disk 13 .

[0053] In an optional embodiment, the graphite tube heating element 4 is provided with a thermal insulation layer outside, and the shell is outside the thermal insulation layer; preferably, the thermal insulation material of the thermal insulation layer is alumina fiber material.

[0054] The thermal insulation material is made of alumina fiber material, which does not drop powder, has good thermal insulation performance, high reflectivity, balanced temperature field, and strong resistance to thermal expansion and contraction.

[0055] In an optional embodiment, the gas uniformizing disk is arranged directly above the wafer, and the gas uniformizing disk is provided with a through hole, which is vertically arranged and has an inner diameter of 1 to 3 mm, for evenly distributing the gas into the reaction chamber to make the reaction more uniform; preferably, the gas uniformizing disk is a quartz gas uniformizing disk.

[0056] In order to achieve better gas uniformity, the gas uniformity disk can be arranged in the following two ways (taking the inner diameter of 2mm as an example):

[0057] (1) Rectangular array arrangement (such as Figure 3 As shown): n rows of parallel through holes are set, 20≤n≤50, the through hole diameter remains unchanged at d1, a through hole with a diameter of d1 is set with the center of the gas uniform disk as the center, and through holes of d1 are distributed in a rectangular array with the through hole as the center, and the adjacent apertures are spaced d2, 1≤d1≤3mm, d1<d2≤6mm;

[0058] (2) Circular array arrangement (such as Figure 4As shown in the figure: Set \(i\) concentric circular through-holes, where \(3\leq i\leq20\). The diameter of the through-holes remains \(d1\) unchanged, with \(1\leq d1\leq3\) mm. There is no through-hole at the center of the gas distributor plate. The distance between the center of the first circle of through-holes and the center of the gas distributor plate is \(d2\), and the difference in the radii of the concentric circles formed by the centers of adjacent circles of through-holes is \(d2\), where \(d1\lt d2\leq6\) mm; the angle formed by the radial lines on the gas distribution plate surface between two adjacent gas distribution holes in the first circle is \(45^{\circ}\); the angle formed by the radial lines on the gas distribution plate surface between two adjacent gas distribution holes in the second circle is \(30^{\circ}\); the angle formed by the radial lines on the gas distribution plate surface between two adjacent gas distribution holes in the third circle is \(20^{\circ}\); when \(3\lt i\leq20\), the angle formed by the radial lines on the spray plate surface between two adjacent spray holes in the \(i\)-th circle is \(10^{\circ}\). As Figure 4 shown, the diameter of the through-hole is 2 mm, the distance between the centers of adjacent circles of through-holes is 5 mm, and \(i = 16\).

[0059] In an alternative embodiment, a clamping groove is provided on the wafer carrier. By adjusting the distance between the clamping grooves, the inter-sheet distance of the sapphire wafers is adjusted, thereby adjusting the distribution of the inter-sheet gas flow field.

[0060] For Figure 3 and Figure 4 two types of gas distributor plates, finite element simulations were respectively carried out to simulate the surface flow field of the first wafer. The results are respectively as Figure 5 and Figure 7 shown. It can be seen that the gas distributor plate arranged in a circular array can bring a better flow field.

[0061] To preheat the gas, a gas preheating graphite plate is provided below the gas distributor plate. The preheating graphite plate and the graphite cylinder heating element are placed within the electromagnetic coil induction range. The preheating graphite plate cooperates with the quartz gas distributor plate. The pore diameter of the preheating graphite plate is smaller than that of the quartz gas distributor plate, and it is 70% - 80% of the latter's pore diameter.

[0062] In an alternative embodiment, from top to bottom, the inter-sheet distance between the sapphire wafers decreases.

[0063] Considering that the carbon source concentration decreases from top to bottom, a design with a decreasing inter-sheet distance from top to bottom is adopted. By reducing the inter-sheet distance, the probability of carbon atom impact is increased, thereby achieving the purpose of confinement. The batch quality uniformity of the prepared graphene wafers is high.

[0064] Preferably, the range of the inter-sheet distance is 2 mm - 15 mm, preferably 4 mm - 10 mm; the difference in the inter-sheet distance between adjacent layers is 1 mm - 3 mm, preferably 1 mm - 2 mm.

[0065] In an alternative embodiment, the sapphire wafer substrate is a C-plane sapphire.

[0066] In an optional embodiment, the wafer carrier 14 is placed on a carrier crucible support platform 16 , and the carrier crucible support platform 16 is connected to a lifting platform 17 , and the lifting platform 17 is connected to a lifting platform transmission rod for adjusting the position of the lifting platform.

[0067] In an optional embodiment, the material of the wafer carrier is alumina ceramic.

[0068] The material of the wafer carrier is alumina ceramic, which can achieve ultra-high temperature growth above 1100°C compared to the quartz carrier commonly used in the prior art, and is conducive to the full cracking of the carbon source.

[0069] In an optional embodiment, the wafer carrier includes at least three columns, wherein at least two columns are fixedly connected and provided with slots to support the wafer; and at least one column is detachably connected to limit the wafer. Figure 7 and Figure 8 As shown, the wafer carrier 14 is composed of a total of 4 columns, among which 3 columns in the upper part are provided with slots to support the wafer, and the bottom column serves as a limiter. Before placing the wafer, pull out the limiter column, clamp the wafer in the corresponding slot in turn, and then insert the limiter column to prevent the wafer from falling.

[0070] In an optional embodiment, it also includes:

[0071] The upper stainless steel flange 1 is located on the upper surface of the housing 6. An air inlet valve is provided in the middle of the upper stainless steel flange 1. The gas passes through the air inlet 11 and the gas distribution plate 3 in sequence, so that the gas entering the reaction chamber is evenly distributed. The upper stainless steel flange 1 and the gas distribution plate 3 are provided with thermocouple jacks for the thermocouple 12 to extend into the furnace body to monitor the temperature in real time.

[0072] The lower stainless steel flange 7 has a vacuum chamber 8 welded thereon, a furnace door is provided at the upper end of the vacuum chamber 8 for taking materials from the furnace door, and a gas outlet channel is provided at the lower end of the vacuum chamber 8 for controlling the chamber pressure through a vacuum system.

[0073] In an optional embodiment, the device further comprises: a cooling water system, which is respectively arranged at the upper and lower stainless steel flanges, and cooling circulating water is passed from bottom to top, and cooling circulating water is also passed through the intermediate frequency coil.

[0074] In an optional embodiment, a tungsten-rhenium thermocouple is inserted into the upper stainless steel flange 1 to monitor the temperature of the process chamber. PID control is adopted to perform programmed temperature-controlled heating on the wafer. The current output size can be manually adjusted at the same time, and the equipment has over-temperature protection.

[0075] In the technical solution of the present invention, the lower stainless steel flange 7 is connected to the vacuum chamber, and the wafer material can be brought to the heating zone by the automatic lifting platform, and can be taken out from the front furnace door of the vacuum chamber after being lowered, so that the material can be put in and taken out conveniently. The lifting platform is limited both up and down to protect the equipment to the maximum extent.

[0076] In an optional embodiment, the shell is a sealed quartz tube.

[0077] The present invention also provides a method for batch preparing high-quality graphene wafers on a sapphire wafer substrate, comprising using the above-mentioned device, specifically comprising the following steps:

[0078] (1) Place sapphire wafers into a wafer carrier and fix them in sequence, place the wafer carrier into the carrier crucible support of the lifting platform, lift the wafer to the middle of the intermediate frequency coil, and close the furnace door;

[0079] (2) Turn on the vacuum pump and set the growth pressure required for the reaction;

[0080] (3) Turn on the temperature control system, set the growth temperature and growth time required for the reaction, and set the heating rate in stages as follows: 25°C / min for the 20°C-500°C stage, 20°C / min for the 500°C-1000°C stage, 10°C / min for the 1000°C-1200°C stage, and 7.5°C / min from 1200°C to the growth temperature;

[0081] (4) Open the mass flow controller to introduce argon gas. When the temperature rises to 500°C, open the mass flow controller to introduce hydrogen gas.

[0082] (5) When the temperature rises to the set growth temperature, keep it warm for 10 minutes, and open the mass flow controller to introduce growth gas methane;

[0083] (6) After the growth is completed, the heating system is turned off, the methane is turned off, and the temperature is lowered in an argon and hydrogen environment. When the temperature is lower than 500° C., the hydrogen is turned off;

[0084] (7) When the temperature is lower than 100° C., turn off the mass flow controller to turn off the argon gas, turn off the vacuum pump, perform vacuum breaking, lower the lifting platform, and obtain a graphene sapphire wafer.

[0085] In an optional embodiment, the method further includes pre-processing the sapphire wafer:

[0086] 1) Clean the sapphire wafer three times in alcohol / acetone and water, and blow it dry with a nitrogen gun for later use;

[0087] 2) Use a dust collector to vacuum the process chamber to remove residual impurities in the process chamber;

[0088] 3) Use argon to purge the process chamber to remove residual gas.

[0089] In an optional embodiment, the growth pressure is 2000Pa-5000Pa; preferably, the growth pressure is 4000Pa.

[0090] In an optional embodiment, the growth temperature is 1275°C-1400°C; preferably, the growth temperature is 1380°C.

[0091] In an optional embodiment, the growth time is 20 min-60 min; preferably, the growth time is 40 min.

[0092] In an optional embodiment, the flow rate of the argon gas is 500 sccm-1000 sccm.

[0093] In an optional embodiment, the flow rate of the hydrogen gas is 300 sccm-500 sccm.

[0094] In an optional embodiment, the flow ratio of argon gas to hydrogen gas is 10:3 to 10:5.

[0095] In an optional embodiment, the growth gas is methane.

[0096] In an optional embodiment, the flow rate of the growth gas is 60 sccm-200 sccm.

[0097] Example 1

[0098] (1) Place 5 sapphire wafers into a wafer carrier and fix them in sequence. From top to bottom, the interlayer spacing decreases to 10 mm, 8 mm, 6 mm, 5 mm, and 4 mm, respectively. Place the wafer carrier in the carrier crucible support of the lifting platform, raise the wafer to the middle of the intermediate frequency coil, and close the furnace door;

[0099] (2) Turn on the vacuum pump and set the reaction growth pressure to 3000 Pa;

[0100] (3) Turn on the temperature control system, set the reaction temperature to 1380°C, and set the heating rate in stages as follows: 25°C / min for 20-500°C, 20°C / min for 500-1000°C, 10°C / min for 1000-1200°C, and 7.5°C / min for 1200°C to 1380°C;

[0101] (4) Open the mass flow controller to introduce argon gas. When the temperature rises to 500°C, open the mass flow controller to introduce hydrogen gas.

[0102] (5) When the temperature rises to the set growth temperature, keep it warm for 10 min, and turn on the mass flow controller to introduce the growth gas methane.

[0103] (6) After the growth is completed, turn off the heating system, turn off methane, and cool down in an argon and hydrogen environment. When the temperature is lower than 500 °C, turn off hydrogen.

[0104] (7) When the temperature is lower than 100 °C, turn off the mass flow controller, turn off argon, turn off the vacuum pump, perform vacuum breaking treatment, and lower the lifting table to obtain a graphene sapphire wafer.

[0105] (8) The gas distributor plate adopts a quartz gas distributor plate (the structure is as Figure 4 shown): Among them, the aperture of the gas distributor plate remains 2 mm, there is no through hole in the center of the gas distributor plate, the distance between the center of the first ring of gas distribution holes and the center of the gas distributor plate is 5 mm, and the radius difference of the concentric circles formed by the centers of the adjacent two rings of gas distribution holes is 5 mm; where i refers to the i-th ring in the order from the innermost ring of gas distribution holes to the outermost ring of gas distribution holes, and i ≤ 16. When i = 1, the included angle formed by the radial straight lines on the gas distribution plate where two adjacent gas distribution holes on the i-th ring are located is 45°; when i = 2, the included angle formed by the radial straight lines on the gas distribution plate where two adjacent gas distribution holes on the i-th ring are located is 30°; when i = 3, the included angle formed by the radial straight lines on the gas distribution plate where two adjacent gas distribution holes on the i-th ring are located is 20°; when 3 < i ≤ 16, the included angle formed by the radial straight lines on the spray plate where two adjacent spray holes on the i-th ring are located is 10°; in this embodiment, the total number of rings is 16.

[0106] Unless otherwise specified, the terms used in the present invention have the meanings commonly understood by those skilled in the art.

[0107] The embodiments described in the present invention are only for illustrative purposes and are not intended to limit the protection scope of the present invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A device for preparing a graphene wafer, characterized in that: The device includes: A housing; A reaction chamber located in the middle of the housing, which consists of a graphite tube heating element and a wafer carrier placed inside the graphite tube heating element; An intermediate frequency coil located outside the housing, the intermediate frequency coil corresponding to the position of the graphite tube heating element, and the graphite tube heating element being within the induction heating range of the intermediate frequency coil; Wherein, a limiting component is provided on the wafer carrier for limiting the positions of multiple wafers.

2. The device according to claim 1, characterized in that A gas preheating graphite disk is provided above the graphite tube heating element, and the preheating graphite disk is within the induction heating range of the intermediate frequency coil.

3. The device according to claim 1, characterized in that An air distribution disk is arranged directly above the wafer. The air distribution disk is provided with through holes. The through holes are arranged vertically and have an inner diameter of 1 - 3 mm, for uniformly distributing gas into the reaction chamber to make the reaction more uniform; preferably, the air distribution disk is a quartz air distribution disk.

4. The device according to claim 3, characterized in that The air distribution disk adopts any one of the following two arrangement methods: (1) Rectangular array arrangement: Set n rows of parallel through holes, 20 ≤ n ≤ 50, the through hole diameter remains d1 unchanged. A through hole with a diameter of d1 is set with the center of the air distribution disk as the center. Taking this through hole as the center, through holes with a diameter of d1 are distributed in a rectangular array, and the adjacent hole diameter intervals are d2, 1 ≤ d1 ≤ 3 mm, d1 < d2 ≤ 6 mm; (2) Circular array arrangement: Set i circles of concentric through holes, 3 ≤ i ≤ 20, the through hole diameter remains d1 unchanged, 1 ≤ d1 ≤ 3 mm, and no through hole is set at the center of the air distribution disk. The distance between the center of the first circle of through holes and the center of the air distribution disk is d2, and the difference in the radii of the concentric circles formed by the centers of the adjacent two circles of through holes is d2, d1 < d2 ≤ 6 mm; the included angle formed by the radial straight lines of the air distribution plate where two adjacent air distribution holes are located on the first circle is 45°; the included angle formed by the radial straight lines of the air distribution plate where two adjacent air distribution holes are located on the second circle is 30°; the included angle formed by the radial straight lines of the air distribution plate where two adjacent air distribution holes are located on the third circle is 20°; when 3 < i ≤ 20, the included angle formed by the radial straight lines of the air distribution plate where two adjacent spray holes are located on the i-th circle is 10°.

5. The device according to claim 1, characterized in that The wafer carrier is provided with card slots, and by adjusting the card slot spacing, the inter-wafer spacing of the wafers is adjusted, thereby adjusting the inter-layer gas flow field distribution.

6. The device according to claim 5, characterized in that From top to bottom, the card slot spacing decreases.

7. The device according to claim 1, characterized in that The material of the wafer carrier is alumina ceramic.

8. The device according to claim 1, characterized in that The wafer carrier includes at least three columns. Among them, at least two columns are fixedly connected, and the columns are provided with card slots to support the wafers; at least one column is detachably connected to limit the wafers.

9. The device according to claim 1, characterized in that It further includes: The housing is a sealed quartz tube.

10. A method for preparing high-quality graphene wafers on a sapphire wafer substrate, characterized in that: Including using the device according to any one of claims 1 - 9, including the following steps: (1) Sequentially place sapphire wafers into the wafer carrier and fix them, raise the wafers to the middle of the intermediate frequency coil, and close the furnace door; (2) Open the vacuum pump and set the growth pressure required for the reaction; (3) Turn on the temperature control system, set the growth temperature and growth time required for the reaction, and set the heating rate in stages as follows: 25°C / min for the 20-500°C stage, 20°C / min for the 500-1000°C stage, 10°C / min for the 1000-1200°C stage, and 7.5°C / min from 1200°C to the growth temperature; (4) Open the mass flow controller to introduce argon gas. When the temperature rises to 500°C, open the mass flow controller to introduce hydrogen gas. (5) When the temperature rises to the set growth temperature, keep it warm for 10 min, and open the mass flow controller to introduce the carbon source gas; (6) After the growth is completed, the heating system is turned off, the carbon source gas is turned off, and the temperature is lowered in an argon and hydrogen environment. When the temperature is lower than 500° C., the hydrogen is turned off; (7) When the temperature is lower than 100° C., turn off the mass flow controller to turn off the argon gas, turn off the vacuum pump, perform vacuum breaking, lower the lifting platform, and obtain a graphene sapphire wafer.

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