A method for dynamic compensation optimization of chemical vapor deposition for preparing super-thick coating

Abstract

The application discloses a method for preparing an ultrathick coating by dynamic compensation and optimization of chemical vapor deposition, and belongs to the technical field of coating preparation. The method comprises the following steps: firstly, a three-dimensional chemical vapor deposition model without a coating and with a predicted coating thickness is established, and the change of the substrate surface deposition rate caused by the growth of the coating is analyzed; then, the deposition conditions are regulated and controlled through fluid mechanics simulation, so that the dynamic compensation and regulation of the deposition process are realized, the surface deposition rate of the ultrathick coating is maintained relatively stable during the growth process, and the problem that the existing fluid mechanics simulation cannot adapt to the large deviation between the initial conditions and the chamber geometry distribution in the later stage of the growth of the ultrathick coating can be effectively solved. The method can adapt to the regulation process of the preparation of different ultrathick coatings by various chemical vapor deposition methods, and is especially suitable for the batch production of multiple substrates. The method greatly saves the experimental trial and error time and economic cost, improves the growth design efficiency of the ultrathick coating, and has important application prospects.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coating preparation, and particularly relates to a method for preparing an ultra-thick coating by dynamic compensation and optimization of chemical vapor deposition. BACKGROUND

[0002] In recent years, with the needs of the third generation semiconductor production equipment and high-temperature protective coating, high-temperature-resistant and corrosion-resistant coatings such as SiC and TaC materials have attracted widespread attention, and can be used in extreme temperature, mechanical load, heat flow and chemical corrosion environment. As a coating preparation technology with good substrate geometry adaptability, high surface coverage, easy-to-control precursor ratio and coating thickness, chemical vapor deposition (CVD) can deposit a coating with good uniformity, high crystallinity and high density at a relatively low temperature, and has become one of the mainstream coating preparation technologies.

[0003] With the expansion of application scenarios and service environments, thinner coatings have been unable to meet the application of various scenarios, and the application advantages of ultra-thick coatings in some service environments are more obvious, and have attracted more and more attention. However, unlike the deposition process of thinner coatings, the thickness change caused by coating deposition during the deposition process of ultra-thick coatings is more obvious, and has a certain influence on the geometric arrangement of the reaction chamber. In addition, in order to improve production efficiency, as many substrates as possible are usually deposited simultaneously in production. Therefore, this phenomenon is more obvious in a multi-substrate deposition system, and the thickness change of the coating will cause changes in the spacing between the substrates and the spacing between the substrate and the wall, thereby affecting the flow field distribution, the deposition rate of the coating, etc. This will make the deposition conditions of the surface in the initial growth stage of the coating significantly different from those of the surface in the later growth stage of the coating, and it is difficult to ensure the consistency of the coating growth environment, greatly reducing the quality and longitudinal uniformity of the grown coating.

[0004] The current thermal and flow field design of chemical vapor deposition is usually based on substrates without coating thickness and chamber arrangement, which is used to guide the experiment. This strategy is suitable for the growth process of micron-level thinner coatings, but when the grown coating is thicker to centimeter level, the coating thickness is approximately bulk, the geometric distribution of the deposition chamber has deviated from the initial condition, and the flow field environment will also change accordingly. The influence of the coating on the geometric distribution inside the chamber cannot be ignored, especially in industrialized mass production, this influence will further become significant. This will inevitably lead to differences in the deposition conditions of the early grown coating and the later grown coating, and further lead to differences in the microstructure, and finally stress and cracks will inevitably appear, reducing the performance of the coating. The traditional flow field analysis method cannot meet the needs of the growth of ultra-thick coatings. Therefore, it is necessary to optimize the existing thermal and flow field design strategy to meet the needs of the deposition and growth of ultra-thick coatings. SUMMARY

[0005] In order to make up for the deficiency of the existing chemical vapor deposition technology for preparing the super-thick coating strategy, the application provides a method for dynamically compensating and optimizing the chemical vapor deposition for preparing the super-thick coating, simulation design is carried out before the deposition of the super-thick coating, and dynamic compensation and optimization guidance is provided for the actual production process of the super-thick coating, so that the deposition rate of the coating surface can be stably controlled, the deposition conditions of the surface in the deposition process of the super-thick coating do not change significantly with the change of the coating thickness, and are in a relatively stable state, thereby providing an effective means for the high-quality deposition of the super-thick coating.

[0006] In order to solve the above technical problems, the application adopts the following technical solutions:

[0007] The application provides a method for dynamically compensating and optimizing the chemical vapor deposition for preparing the super-thick coating, which comprises the following steps:

[0008] 1) A simplified three-dimensional model of no coating thickness and a predicted coating thickness is respectively established by using the chemical vapor deposition equipment;

[0009] 2) The simplified three-dimensional model generated in step 1) is respectively meshed to generate a mesh file;

[0010] 3) The mesh file obtained in step 2) is imported into the simulation solving software of computational fluid dynamics, a physical model is set, then corresponding boundary conditions are set, and then iterative solving is carried out, so as to respectively obtain the deposition rate when there is no coating thickness and when there is a predicted coating thickness;

[0011] 4) The deposition rate change conditions obtained in step 3) when there is no coating thickness and when there is a predicted coating thickness are compared and analyzed, and the boundary conditions of the model with the predicted coating thickness are corrected so that the deposition rate of the growth surface of the model with the predicted coating thickness approaches the simulation result of no coating thickness;

[0012] 5) In the actual deposition of the super-thick coating, the boundary condition parameters of the deposition are adjusted from the initial parameters to the end parameters in a linear change manner with the increase of the coating thickness, the initial parameters are the boundary conditions when there is no coating thickness, and the end parameters are the boundary conditions of the model with the predicted coating thickness obtained in step 4), so as to realize the dynamic compensation deposition of the super-thick coating.

[0013] According to the above scheme, in step 1), the simplified three-dimensional model is established by using Spaceclaim software.

[0014] According to the above scheme, in step 1), when the simplified three-dimensional model is established, the related parameters include the arrangement of the inlet and outlet, the size of the chamber, the number of substrates, and the placement mode of the substrates.

[0015] According to the above scheme, in step 1), when the simplified three-dimensional model is established, the calculation solving region only contains the fluid domain range inside the cavity.

[0016] According to the above scheme, in the step 2), the meshing is performed by using Fluent Meshing software.

[0017] According to the above scheme, in the step 3), the simulation solving software is Fluent.

[0018] According to the above scheme, in the step 3), the physical model includes a flow model, a radiation model and a component transport model; preferably, the flow model adopts a standard k-ε turbulent flow model; the radiation model adopts a DO model; and the component transport model adopts a Species Transport finite speed model.

[0019] According to the above scheme, in the step 3), the boundary conditions include an inlet flow rate, a precursor ratio, an inlet temperature, a substrate rotation speed, an inlet type, an outlet type, a wall temperature and a deposition pressure.

[0020] Preferably, the inlet type is a velocity inlet, and the outlet type is a pressure outlet.

[0021] According to the above scheme, in the step 3), the iterative solving adopts a Coupled coupling algorithm.

[0022] According to the above scheme, in the step 4), when the absolute deviation of the surface average deposition rate of the system with the coating thickness from the surface deposition rate of the system without the coating thickness is more than 5%, the boundary conditions are adjusted to make the absolute deviation of the surface average deposition rate less than 5%.

[0023] According to the above scheme, in the step 4), in the adjustment of the boundary conditions with the expected coating thickness, one or more boundary conditions are selected for adjustment.

[0024] The method for preparing the ultra-thick coating by the above dynamic compensation and optimization chemical vapor deposition method is provided, and the ultra-thick coating prepared by the method has a thickness of 1-4 mm.

[0025] According to the above scheme, the ultra-thick coating is dense, has good longitudinal uniformity, and has no cracks and delamination in the cross section.

[0026] The beneficial effects of the present application are as follows:

[0027] 1.The application provides a method for dynamically compensating and optimizing chemical vapor deposition to prepare an ultrathick coating, a three-dimensional chemical vapor deposition model of no coating and a predicted coating thickness is established, changes in the deposition rate of the substrate surface caused by the growth of the coating are analyzed, and then the deposition conditions are regulated through fluid dynamics simulation to realize dynamic compensation and regulation of the deposition process, so that the surface deposition rate of the ultrathick coating remains relatively stable during the growth process, which can effectively solve the problem that the existing fluid dynamics simulation cannot adapt to the large deviation of the initial conditions of the chamber geometry distribution in the later stage of the growth of the ultrathick coating, can adapt to the regulation process of preparing different ultrathick coatings by various chemical vapor deposition methods, especially for batch production of multiple substrates, greatly saves the experimental trial and error time and economic cost, improves the growth design efficiency of the ultrathick coating, and has important application prospects.

[0028] 2.The ultrathick coating prepared by the method of the application has a dense deposited coating, good longitudinal uniformity, no cracks or delamination in the cross section, and has practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Figure 1 is a flowchart of a dynamic compensation simulation method for chemical vapor deposition of an ultrathick coating according to an embodiment of the application.

[0030] Figure 2 Figure 2 is a simplified schematic diagram of a three-dimensional model of an ultrathick silicon carbide coating deposition equipment according to an embodiment of the application, wherein the thickness of the substrate is 4mm, (a) is a three-dimensional model without coating thickness, and (b) is a three-dimensional model after the upper and lower surfaces of the substrate are each deposited with a 3mm thick coating.

[0031] Figure 3 Figure 3 is a cross-sectional SEM image of an ultrathick silicon carbide coating obtained in an embodiment of the application.

[0032] Figure 4 Figure 4 is a surface SEM image of an ultrathick silicon carbide coating obtained in an embodiment of the application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the application clearer and more apparent, the application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0034] The application aims to provide a dynamic compensation deposition strategy for the chemical vapor deposition process of an ultrathick coating combined with fluid dynamics simulation to realize stable and efficient deposition of the ultrathick coating.

[0035] As shown in Figure 1 Figure 1, the embodiment of the application provides a method for dynamically compensating and optimizing chemical vapor deposition to prepare an ultrathick coating, which comprises the following steps:

[0036] 1) Establish a simplified three-dimensional model of the thickness of the coating without coating and the thickness of the coating to be deposited respectively by chemical vapor deposition equipment;

[0037] 2) Grid the simplified three-dimensional model generated in step 1) respectively to generate a grid file;

[0038] 3) Import the grid file obtained in step 2) into the simulation solving software of computational fluid dynamics, set the physical model, then set the corresponding boundary conditions, and then perform iterative solving to obtain the deposition rate when the thickness of the coating without coating and the thickness of the coating with the expected coating thickness respectively;

[0039] 4) Compare and analyze the deposition rate changes of the thickness of the coating without coating and the thickness of the coating with the expected coating thickness obtained in step 3), and correct the boundary conditions of the thickness of the coating with the expected coating thickness to make the deposition rate of the growth surface of the model with the expected coating thickness close to the simulation result of the thickness of the coating without coating;

[0040] 5) In the actual deposition of the super-thick coating, the boundary condition of the coating without coating is used as the initial parameter, and the boundary condition of the coating with the expected coating thickness obtained in step 4) is used as the terminal parameter. With the increase of the thickness of the coating, the deposition boundary condition parameter is adjusted from the initial parameter to the terminal parameter in a linear manner to realize the dynamic compensation deposition of the super-thick coating.

[0041] In one embodiment, in step 1), a simplified three-dimensional model is established using Spaceclaim software, and the calculation solving region only includes the fluid domain range inside the cavity.

[0042] In one embodiment, in step 1), when establishing a simplified three-dimensional model, the relevant parameters include the arrangement of the inlet and outlet, the size of the cavity, the number of substrates, and the placement method of the substrates.

[0043] In one embodiment, in step 2), Fluent Meshing software is used for grid division.

[0044] In one embodiment, in step 3), the simulation solving software is Fluent.

[0045] In one embodiment, in step 3), the physical model includes a flow model, a radiation model, and a component transport model; preferably, the flow model uses a standard k-ε turbulence model; the radiation model uses a DO model; and the component transport model uses a Species Transport finite speed model.

[0046] In one embodiment, in step 3), the boundary conditions include the inlet flow rate, precursor ratio, inlet temperature, substrate rotation speed, inlet type, outlet type, wall temperature, and deposition pressure. Preferably, the inlet type is a velocity inlet, and the outlet type is a pressure outlet.

[0047] In one embodiment, in step 3), the iterative solution adopts a Coupled coupling algorithm.

[0048] In one embodiment, in step 4), when the absolute value of the deviation of the surface average deposition rate of the system with the coating thickness from the surface deposition rate of the model without the coating thickness is greater than 5%, the surface average deposition rate is corrected to an absolute value of less than 5%.

[0049] In one embodiment, in step 4), in the correction of the boundary conditions with the predicted coating thickness, one or more boundary conditions are selected for correction.

[0050] Embodiment 1

[0051] A method for dynamically compensating and optimizing the preparation of an ultra-thick coating by chemical vapor deposition is provided, comprising the following steps:

[0052] First, a three-dimensional simplified model without a coating thickness and a three-dimensional simplified model with a predicted coating thickness are established using Spaceclaim software, respectively, and meshing is performed to generate a mesh file. The generated mesh file is imported into the solver Fluent, and the physical model is set, including a flow model, a radiation model, and a component transport model. The flow model adopts a standard k-ε model, the flow state is turbulent flow, the radiation model adopts a DO model, and the component transport model adopts a Species Transport finite speed model. Subsequently, the boundary conditions are set: inlet flow rate, precursor ratio, inlet temperature, substrate rotation speed, inlet type, outlet type, wall temperature, and deposition pressure, and the Coupled coupling algorithm is used for iterative solution. In the initial calculation, the boundary conditions without a coating thickness and with a predicted coating thickness need to be consistent, which facilitates the comparison of the change in the surface deposition rate caused by the change in the coating thickness for the next step of regulation and control.

[0053] As Figure 2(a) As shown, the present embodiment provides a high-temperature hot-wall chemical vapor deposition system for dynamically regulating the growth of a SiC super-thick coating. The system is a multi-substrate reaction chamber, and the simplified model only includes the fluid domain inside the chamber. The overall chamber height is 0.132 m. There are three parallel gas inlets on the left side of the chamber, each with a diameter of 0.01 m. There are two parallel gas outlets on the right side of the chamber, each with a diameter of 0.02 m. The substrate is a graphite substrate with a diameter of 0.1 m and a thickness of 0.004 m. The gas inlet temperature is 353 K, the wall temperature is 1573 K, the deposition pressure is 10 kPa, and the substrate rotates along the z-axis at a speed of 60 rpm. The gas flow rate is 0.255 m / s, and the molar ratio of the mixed gas is H2:SiCl4:CH4 = 10:1:1. The outlet is a pressure outlet. The convergence criteria for the energy and mass conservation equations are 1e-6, and the convergence criteria for other monitored values are 1e-3. At the same time, speed monitoring points are set inside the chamber, and SiC deposition rate monitoring points are set on the surface of the substrate. When the residual error reaches the convergence criteria and the values of the monitoring points no longer fluctuate significantly, the calculation is considered to have converged.

[0054] Figure 2 (b) is a simplified model after growing a 0.003 m thick coating on the upper and lower surfaces of the substrate. The calculation parameters are the same as above. Taking the upper surface of the uppermost substrate as the monitoring object, when the boundary conditions are the same, the average SiC deposition rate of the monitoring surface of the model without coating thickness and the model with a 3 mm thick coating differs by -10.5%, and the deposition rate is significantly slower. Therefore, it is necessary to adjust the deposition conditions of the model with a 0.003 m coating thickness to reduce the degree of deviation of the deposition rate. In this example, the deposition rate is adjusted by changing the deposition pressure, as shown in Table 1. When the deposition pressure increases from the initial 10 kPa to 10.5 kPa, the average deposition rate of the monitoring surface without coating thickness deviates by only -1.91%, so it can be judged that the adjustment requirements are met. Therefore, the deposition pressure is gradually increased by 100 Pa every two hours during the deposition process, and the total deposition time is 10 hours. The super-thick coating obtained by deposition is shown in Figure 3 、 Figure 4 .

[0055] Figure 3 is a cross-sectional SEM image of the deposited super-thick SiC coating. The cross-section has no cracks or delamination, the deposited coating is dense, and the longitudinal uniformity is good. Figure 4 is a surface SEM image of the deposited super-thick SiC coating. The surface is dense and the particles are uniform.

[0056] Table 1 shows the degree of deviation of the average SiC deposition rate of the monitoring surface after adjusting the deposition pressure in the example from the initial deposition rate without coating thickness. When the deposition pressure increases to 10.5 kPa, the absolute value of the deposition rate deviation is less than 5%.

[0057] Table 1. Degree of deviation of the average SiC deposition rate on the monitored surface after adjusting the deposition pressure in Example 1

[0058]

[0059] It is to be understood that all such modifications and variations that can be effected without departing from the scope of the present application are considered within the purview of the inventive concept disclosed herein.

Claims

1. A method for dynamically compensating and optimizing the preparation of ultra-thick coatings by chemical vapor deposition, characterized in that, Includes the following steps: 1) Simplified three-dimensional models of the uncoated thickness and the expected coating thickness were established using chemical vapor deposition equipment; 2) Mesh the simplified 3D model generated in step 1) to generate mesh files; 3) Import the mesh file obtained in step 2) into the computational fluid dynamics simulation software, set the physical model, then set the corresponding boundary conditions, and then perform iterative solution to obtain the deposition rate with no coating thickness and with the expected coating thickness, respectively. 4) Compare and analyze the changes in deposition rate obtained in step 3) with the uncoated thickness and with the expected coating thickness. By modifying the boundary conditions with the expected coating thickness, the surface deposition rate of the model with the expected coating thickness is made close to the simulation results of the uncoated thickness. 5) In the actual deposition of ultra-thick coatings, the boundary conditions without coating thickness are used as the initial parameters, and the boundary conditions with the expected coating thickness obtained in step 4) are used as the endpoint parameters. As the coating thickness increases, the boundary condition parameters of the deposition are adjusted from the initial parameters to the endpoint parameters in a linear manner to achieve dynamic compensation deposition of ultra-thick coatings.

2. The method according to claim 1, characterized in that, In step 1), when establishing the simplified three-dimensional model, the relevant parameters include the arrangement of inlet and outlet, chamber size, number of substrates, and substrate placement method.

3. The method according to claim 1, characterized in that, In step 1), when establishing the simplified three-dimensional model, the calculation solution region only includes the fluid domain inside the cavity.

4. The method according to claim 1, characterized in that, In step 1), a simplified 3D model is created using Spaceclaim software; in step 2), Fluent Meshing software is used for mesh generation.

5. The method according to claim 1, characterized in that, In step 3), the physical model includes a flow model, a radiation model, and a component transport model.

6. The method according to claim 1, characterized in that, In step 3), the boundary conditions include inlet flow rate, precursor ratio, inlet temperature, substrate rotation speed, inlet type, outlet type, wall temperature, and deposition pressure.

7. The method according to claim 1, characterized in that, In step 3), the simulation solution software is Fluent; the iterative solution uses the Coupled algorithm.

8. The method according to claim 1, characterized in that, In step 4), when the absolute value of the deviation between the average surface deposition rate of the system with coating thickness and the surface deposition rate of the model without coating thickness is greater than 5%, the boundary conditions are adjusted to correct the deviation to less than 5%.

9. The method according to claim 1, characterized in that, In step 4), one or more boundary conditions are selected for correction when modifying the boundary conditions with the expected coating thickness.

10. An ultra-thick coating prepared by a method for dynamically compensated optimized chemical vapor deposition according to any one of claims 1-9, characterized in that, The thickness of the ultra-thick coating is 1 to 4 mm.

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