Preparation method of cubic silicon carbide coating with controllable out-of-plane thermal conductivity

Abstract

The invention relates to a preparation method of a cubic silicon carbide coating with controllable out-of-plane thermal conductivity, which comprises the following specific steps: 1) pretreating a graphite substrate, putting the pretreated graphite substrate on a substrate seat of vertical hot wall type chemical vapor deposition equipment, and vacuumizing until the vacuum degree is below 10Pa; 2) heating the substrate seat to a set deposition temperature; and (3) diluted gas H2 is introduced into chemical vapor deposition equipment, then SiCl4 and CH4 are introduced, chemical vapor deposition is carried out after the pressure intensity is stabilized at the set deposition pressure intensity, and the cubic silicon carbide coating with the controllable out-of-plane thermal conductivity is obtained through deposition on the graphite substrate by adjusting the deposition temperature and the deposition pressure intensity. According to the method, the grain boundary angle and the grain size of the silicon carbide coating are controlled by adjusting deposition parameters of the silicon carbide coating, then the out-of-plane heat conductivity of the silicon carbide coating is adjusted and controlled, the silicon carbide coating is suitable for different use scenes, and the problem that in the prior art, the out-of-plane heat conductivity of the silicon carbide coating is poor in control precision is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of plating by vacuum evaporation, sputtering or ion implantation of coating-forming materials, and in particular relates to a method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity. Background Art

[0002] Cubic silicon carbide (3C-SiC) prepared by CVD method has a purity of up to 99.995% and has excellent out-of-plane and in-plane orientation. It is widely used in semiconductor single crystal growth or structural components of epitaxial furnaces, such as wafer inductors, wafer trays, etc. Its ultra-high purity can reduce the impurity content in the product. At the same time, good in-plane and out-of-plane orientation makes heat transfer more efficient and temperature distribution more uniform. Compared with 4H-SiC, 6H-SiC and 15R-SiC, 3C-SiC can achieve relatively excellent thermal conductivity at a lower cost due to its advantages of low preparation temperature and low defect density, and has become a hot spot in thermal conductivity research.

[0003] In actual use, the requirements for thermal conductivity of materials are becoming more and more sophisticated. Not only the in-plane thermal conductivity is considered, but the out-of-plane thermal conductivity is also a key factor affecting the temperature uniformity and heat transfer efficiency of the material, and is becoming more and more important. For example, in semiconductor production, the wafer tray has higher and higher precision requirements for the temperature uniformity and heat transfer efficiency of the silicon carbide coating. Therefore, the out-of-plane thermal conductivity of the silicon carbide coating needs to be adjustable, but there is currently no accurate and practical method for regulating the out-of-plane thermal conductivity. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity in view of the deficiencies in the prior art.

[0005] The present invention provides a method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity, and the specific steps are as follows:

[0006] 1) placing the graphite substrate after pretreatment on a substrate holder of a vertical hot wall chemical vapor deposition device, and evacuating the substrate to a vacuum degree of less than 10 Pa;

[0007] 2) Start the heating power supply and circulating water cooling device, heat the substrate holder to the set deposition temperature at a heating rate of 10-20°C / min, and keep the temperature for 20 minutes every time the temperature rises by 200°C during the heating process;

[0008] 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment until the pressure reaches the set deposition pressure ±

[0009] 500Pa, then SiCl4 and CH4 are introduced, and chemical vapor deposition is carried out after the pressure stabilizes at the set deposition pressure. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chemical vapor deposition equipment chamber is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time. By adjusting the deposition temperature and deposition pressure, a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0010] According to the above scheme, the graphite substrate in step 1) is high-purity graphite with a purity of more than 99.99wt%, and its pretreatment method is: the graphite substrate is polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then vacuum dried.

[0011] According to the above scheme, the deposition temperature in step 2) is 1400-1600°C.

[0012] According to the above scheme, in step 3), the purity of H2 is above 99.999 vol%, and the flow rate is 1000-5000 sccm; the flow rate of SiCl4 is 100-1000 sccm, and the purity of CH4 is above 99.999 vol%, and the flow rate is 100-1000 sccm.

[0013] According to the above scheme, the deposition pressure in step 3) is 4×10 3 -10 4 Pa.

[0014] According to the above scheme, the time of step 3) chemical vapor deposition is 2-3 hours.

[0015] According to the above scheme, in step 3), the silicon carbide coating deposition pressure is 10000Pa, and when the deposition temperature is in the range of 1673-1873K, the grain size is 2.49-20.1μm, the grain boundary angle is controlled at 38-41°, and the out-of-plane thermal conductivity is adjustable in the range of 94.1-245W / m K as the deposition temperature increases;

[0016] When the deposition pressure is 4000 Pa and the deposition temperature is 1823 °C, the grain size is 12.43 μm, the grain boundary angle is 58°, and the out-of-plane thermal conductivity is 122.3 W / m K.

[0017] The present invention adjusts the deposition temperature and deposition pressure conditions in the process of preparing a 3C-SiC film by chemical vapor deposition, and regulates the grain boundary angle and grain size of the 3C-SiC film deposited on a graphite substrate, thereby obtaining a cubic silicon carbide coating with controllable out-of-plane thermal conductivity.

[0018] The beneficial effects of the present invention are as follows: the method of the present invention controls the grain boundary angle and grain size of the silicon carbide coating by adjusting the deposition parameters, thereby regulating its out-of-plane thermal conductivity, making it suitable for different usage scenarios, and having a fast deposition speed (the coating deposition growth rate can reach 950 μm / h), thereby solving the problem of poor control accuracy of the out-of-plane thermal conductivity of the silicon carbide coating in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 XRD diagram of the silicon carbide coating prepared in Examples 1-6 of the present invention;

[0020] Figure 2 The grain size distribution diagram of the silicon carbide coating prepared in Examples 1-6;

[0021] Figure 3 Optical micrographs of the silicon carbide coatings prepared in Examples 1-6;

[0022] Figure 4 TEM images of the silicon carbide coatings prepared in Examples 1-6;

[0023] Figure 5 This is a comparison chart of the out-of-plane thermal conductivity of the silicon carbide coatings prepared in Examples 1-6 measured at different temperatures. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below using embodiments in conjunction with the accompanying drawings.

[0025] Example 1

[0026] A method for preparing a silicon carbide coating comprises the following steps:

[0027] 1) A circular graphite substrate (diameter 100 mm, graphite purity 99.99%) was polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven at 100° C. for 30 minutes to obtain a flat and clean graphite substrate, and the graphite substrate was placed on a substrate holder of a vertical hot wall chemical vapor deposition device, and the chemical vapor deposition device was evacuated to a vacuum degree of 10 Pa. A cold hydrazine was provided at the exhaust port of the vertical hot wall chemical vapor deposition device, and the cold hydrazine was immersed in liquid nitrogen to condense and collect the tail gas;

[0028] 2) Start the heating power supply and the circulating water cooling device, and heat the substrate holder to the set deposition temperature of 1673K at a heating rate of 15°C / min. During the heating process, keep the temperature for 20 minutes every time the temperature rises by 200°C;

[0029] 3) First, introduce dilution gas H2 (99.999 vol%) into the chemical vapor deposition equipment at a flow rate of 3000 sccm until the chamber pressure reaches the set deposition pressure of 10000 Pa, and then introduce SiCl4 and CH4, with a SiCl4 flow rate of 400 sccm and a CH4 (99.999 vol%) flow rate of 300 sccm. After the air pressure in the chemical vapor deposition equipment stabilizes at 10000 Pa, chemical vapor deposition is carried out for 3 hours. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chamber of the chemical vapor deposition equipment is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time, and a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0030] The silicon carbide coating prepared in this embodiment has a (111) plane preferred orientation, a coating thickness of 320 μm, a deposition rate of 107 μm / h, an average grain size of the obtained coating of 2.49 μm, a grain boundary angle of 41°, and an out-of-plane thermal conductivity of 94.1 W / m K.

[0031] Example 2

[0032] A method for preparing a silicon carbide coating comprises the following steps:

[0033] 1) The graphite substrate was polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven to obtain a flat and clean graphite substrate. The graphite substrate was placed on a substrate holder of a vertical hot wall chemical vapor deposition device, and the chemical vapor deposition device was evacuated to a vacuum degree of 10 Pa;

[0034] 2) Start the heating power supply and circulating water cooling device, heat the substrate holder to the set deposition temperature of 1723K at a heating rate of 15°C / min, and keep the temperature for 20 minutes every time the temperature rises by 200°C during the heating process;

[0035] 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment at a flow rate of 3000sccm until the chamber pressure reaches the set deposition pressure of 10000Pa, and then introduce SiCl4 and CH4, with a SiCl4 flow rate of 400sccm and a CH4 flow rate of 300sccm. After the gas pressure in the chemical vapor deposition equipment stabilizes at 10000Pa, chemical vapor deposition is carried out for 3 hours. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chamber of the chemical vapor deposition equipment is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time, and a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0036] The silicon carbide coating prepared in this embodiment has a (111) plane preferred orientation, a coating thickness of 750 μm, a deposition rate of 250 μm / h, an average grain size of 4.16 μm, a grain boundary angle of 39°, and an out-of-plane thermal conductivity of 110 W / m K.

[0037] Example 3

[0038] A method for preparing a silicon carbide coating comprises the following steps:

[0039] 1) The graphite substrate was polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven to obtain a flat and clean graphite substrate. The graphite substrate was placed on a substrate holder of a vertical hot wall chemical vapor deposition device, and the chemical vapor deposition device was evacuated to a vacuum degree of 10 Pa;

[0040] 2) Start the heating power supply and the circulating water cooling device, and heat the substrate holder to the set deposition temperature of 1773K at a heating rate of 15°C / min. During the heating process, keep the temperature for 20 minutes every time the temperature rises by 200°C;

[0041] 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment at a flow rate of 3000sccm until the chamber pressure reaches the set deposition pressure of 10000Pa, and then introduce SiCl4 and CH4, with a SiCl4 flow rate of 400sccm and a CH4 flow rate of 300sccm. After the gas pressure in the chemical vapor deposition equipment stabilizes at 10000Pa, chemical vapor deposition is carried out for 3 hours. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chamber of the chemical vapor deposition equipment is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time, and a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0042] The silicon carbide coating prepared in this embodiment has a (111) plane preferred orientation, a coating thickness of 790 μm, a deposition rate of 264 μm / h, an average grain size of 6.08 μm, a grain boundary angle of 38°, and an out-of-plane thermal conductivity of 124.6 W / mK.

[0043] Example 4

[0044] A method for preparing a silicon carbide coating comprises the following steps:

[0045] 1) The graphite substrate was polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven to obtain a flat and clean graphite substrate. The graphite substrate was placed on a substrate holder of a vertical hot wall chemical vapor deposition device, and the chemical vapor deposition device was evacuated to a vacuum degree of 10 Pa;

[0046] 2) Start the heating power supply and the circulating water cooling device, and heat the substrate holder to the set deposition temperature of 1823K at a heating rate of 10°C / min. During the heating process, keep the temperature for 20 minutes every time the temperature rises by 200°C;

[0047] 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment at a flow rate of 3000sccm until the chamber pressure reaches the set deposition pressure of 10000Pa, and then introduce SiCl4 and CH4, with a SiCl4 flow rate of 400sccm and a CH4 flow rate of 300sccm. After the gas pressure in the chemical vapor deposition equipment stabilizes at 10000Pa, chemical vapor deposition is carried out for 3 hours. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chamber of the chemical vapor deposition equipment is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time, and a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0048] The silicon carbide coating prepared in this embodiment has a preferred orientation of the (111) plane, a coating thickness of 950 μm, a deposition rate of 317 μm / h, an average grain size of 11.04 μm, a grain boundary angle of 38°, and an out-of-plane thermal conductivity of 146.4 W / mK.

[0049] Example 5

[0050] A method for preparing a silicon carbide coating comprises the following steps:

[0051] 1) The graphite substrate was polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven to obtain a flat and clean graphite substrate. The graphite substrate was placed on a substrate holder of a vertical hot wall chemical vapor deposition device, and the chemical vapor deposition device was evacuated to a vacuum degree of 10 Pa;

[0052] 2) Start the heating power supply and the circulating water cooling device, and heat the substrate holder to the set deposition temperature of 1823K at a heating rate of 10°C / min. During the heating process, keep the temperature for 20 minutes every time the temperature rises by 200°C;

[0053] 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment at a flow rate of 3000sccm until the chamber pressure reaches the set deposition pressure of 4000Pa, and then introduce SiCl4 and CH4, with a SiCl4 flow rate of 400sccm and a CH4 flow rate of 300sccm. After the gas pressure in the chemical vapor deposition equipment stabilizes at 4000Pa, chemical vapor deposition is carried out for 3 hours. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chamber of the chemical vapor deposition equipment is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time, and a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0054] The silicon carbide coating prepared in this embodiment has a (111) plane preferred orientation, a coating thickness of 255 μm, a deposition rate of 85 μm / h, an average grain size of 12.43 μm, a grain boundary angle of 58°, and an out-of-plane thermal conductivity of 122.3 W / mK.

[0055] Example 6

[0056] A method for preparing a silicon carbide coating comprises the following steps:

[0057] 1) The graphite substrate was polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven to obtain a flat and clean graphite substrate. The graphite substrate was placed on a substrate holder of a vertical hot wall chemical vapor deposition device, and the chemical vapor deposition device was evacuated to a vacuum degree of 10 Pa;

[0058] 2) Start the heating power supply and the circulating water cooling device, and heat the substrate holder to the set deposition temperature of 1873K at a heating rate of 10°C / min. During the heating process, keep the temperature for 20 minutes every time the temperature rises by 200°C;

[0059] 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment at a flow rate of 3000sccm until the chamber pressure reaches the set deposition pressure of 10000Pa, and then introduce SiCl4 and CH4, with a SiCl4 flow rate of 400sccm and a CH4 flow rate of 300sccm. After the gas pressure in the chemical vapor deposition equipment stabilizes at 10000Pa, chemical vapor deposition is carried out for 3 hours. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chamber of the chemical vapor deposition equipment is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time, and a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

[0060] The silicon carbide coating prepared in this embodiment has a (111) plane preferred orientation, a coating thickness of 2850 μm, a deposition rate of 950 μm / h, an average grain size of 20.10 μm, a grain boundary angle of 39°, and an out-of-plane thermal conductivity of 245 W / m K.

[0061] Figure 1 This is the XRD diagram of the silicon carbide coating prepared in Example 1-6. Sample 1-6 in the figure corresponds to the sample of Example 1-6. It can be seen that the cubic silicon carbide coating is obtained in Example 1-6.

[0062] Figure 2 (a)-(f) are the grain size distribution diagrams of the silicon carbide coatings prepared in Examples 1-6, respectively, and the inset is the SEM image of the coating surface.

[0063] Figure 3 (a)-(f) are optical micrographs of the silicon carbide coatings prepared in Examples 1-6, respectively, and their porosities are 0.15%, 0.18%, 0.15%, 0.14%, 0.16%, and 0.17%, respectively.

[0064] Figure 4 (a)-(f) are TEM images of the silicon carbide coatings prepared in Examples 1-6, respectively. The silicon carbide grain boundary angles can be obtained based on the TEM images.

[0065] Figure 5 Out-of-plane thermal conductivity of the silicon carbide coatings prepared in Examples 1 to 6 measured at different temperatures. When measuring the out-of-plane thermal conductivity, in order to avoid individual accidental phenomena and ensure the reliability of the thermal conductivity change trend, the out-of-plane thermal conductivity of each embodiment at different temperatures was measured respectively, but when describing the specific value of the out-of-plane thermal conductivity, the value at 300K (i.e. room temperature) is usually used as the standard.

[0066] Please see Table 1 for the test data of Examples 1-6.

[0067] Table 1

[0068]

[0069]

[0070] From the results in Table 1, it can be seen that when the deposition pressure of Examples 1-4 and Example 6 is 10000Pa, as the deposition temperature increases from 1673 to 1873K, the grain size of the coated silicon carbide increases from 2.49μm to 20.1μm, the grain boundary angle is in the range of 38-41°, and the out-of-plane thermal conductivity increases from 94.1W / m K to 245W / m K, indicating that the out-of-plane thermal conductivity of the 3C-SiC film can be controlled by adjusting the preparation conditions. When the deposition pressure of Example 5 is 4000Pa and the deposition temperature is 1823K, compared with the sample of Example 4, the grain size is close, the grain boundary angle increases to 58°, and the out-of-plane thermal conductivity is 122.3W / mK, which is quite different from that of Example 4. This shows that the out-of-plane thermal conductivity of the 3C-SiC film is not only affected by the grain size, but also has a certain relationship with the grain boundary angle.

[0071] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity, characterized in that: The specific steps are as follows: 1) placing the graphite substrate after pretreatment on a substrate holder of a vertical hot wall chemical vapor deposition device, and evacuating the substrate to a vacuum degree of less than 10 Pa; 2) Start the heating power supply and circulating water cooling device, heat the substrate holder to the set deposition temperature at a heating rate of 10-20°C / min, and keep the temperature for 20 minutes every time the temperature rises by 200°C during the heating process; 3) First, introduce dilution gas H2 into the chemical vapor deposition equipment until the pressure reaches the set deposition pressure ±500Pa, and then introduce SiCl4 and CH4. After the pressure stabilizes at the set deposition pressure, chemical vapor deposition is carried out. After the deposition is completed, the heating power supply, SiCl4 and CH4 are turned off. When the chemical vapor deposition equipment cavity is cooled to room temperature, the introduction of H2 is stopped, and the circulating water cooling device is turned off at the same time. By adjusting the deposition temperature and deposition pressure, a cubic silicon carbide coating with controllable out-of-plane thermal conductivity is deposited on the graphite substrate.

2. The method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity according to claim 1, characterized in that: Step 1) The graphite substrate is high-purity graphite with a purity of more than 99.99wt%, and its pretreatment method is: the graphite substrate is polished with 1000-mesh sandpaper, then ultrasonically cleaned in alcohol for 20 minutes, and then vacuum dried.

3. The method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity according to claim 1, characterized in that: Step 2) The deposition temperature is 1400-1600°C.

4. The method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity according to claim 1, characterized in that: Step 3) The purity of H2 is above 99.999 vol%, and the flow rate is 1000-5000 sccm; the flow rate of SiCl4 is 100-1000 sccm, and the purity of CH4 is above 99.999 vol%, and the flow rate is 100-1000 sccm.

5. The method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity according to claim 1, characterized in that: Step 3) The deposition pressure is 4×10 3 -10 4 Pa.

6. The method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity according to claim 1, characterized in that: Step 3) The time for chemical vapor deposition is 2-3 hours.

7. The method for preparing a cubic silicon carbide coating with controllable out-of-plane thermal conductivity according to claim 1, characterized in that: Step 3) When the silicon carbide coating is deposited at a pressure of 10000 Pa and a deposition temperature in the range of 1673-1873 K, the grain size is 2.49-20.1 μm, the grain boundary angle is controlled at 38-41°, and the out-of-plane thermal conductivity is adjustable in the range of 94.1-245 W / m K as the deposition temperature increases; When the deposition pressure is 4000 Pa and the deposition temperature is 1823 °C, the grain size is 12.43 μm, the grain boundary angle is 58°, and the out-of-plane thermal conductivity is 122.3 W / m K.

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