A deposition method for reducing stress in silicon carbide films
By forming silicon carbide grains on the surface of the substrate and annealing, the problem of difficult SiC grains in the early stage of deposition of silicon carbide thin films in the prior art is solved, the deposition efficiency and binding force of the film are improved, and internal stress and waste of raw materials are reduced.
Patent Information
- Application Number
- CN202411967663.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-04-04
AI Technical Summary
In the existing silicon carbide (SiC) film preparation process, SiC grains are difficult to form in the early stage of deposition, resulting in low raw material utilization and large internal stress of the film, affecting the subsequent processing yield, and difficult to control the crystal form matching, resulting in weak bonding between the film and the substrate.
Silicon carbide grains are first formed on the surface of the substrate, and then the grain flatness is improved by annealing treatment. Finally, a silicon carbide film is deposited on the annealed substrate surface by chemical vapor deposition.
The grain flatness of the silicon carbide grains after annealing is improved, the deposition efficiency of the silicon carbide film is improved, the internal stress of the film is reduced, the utilization rate of raw materials is improved, and the bonding force between the film and the substrate is enhanced.
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Figure CN119753625A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a deposition method for reducing stress of a silicon carbide film. Background Art
[0002] In the semiconductor manufacturing process, due to the excellent wear resistance, corrosion resistance and good thermal stability of silicon carbide (SiC), process equipment parts made of silicon carbide have been widely used. Among them, chemical vapor deposition (CVD) is a more commonly used method for preparing silicon carbide.
[0003] The chemical vapor deposition process (CVD) is based on methyltrichlorosilane (MTS / CH3SiCl3) as the main raw material. With the assistance of hydrogen (H2) and argon (Ar), high-quality silicon carbide (SiC) film deposition can be achieved under high temperature conditions (such as around 1500°C). The raw gas (MTS, H2, Ar) is introduced into the CVD reaction chamber and mixed by natural convection or forced flow. Under high temperature, MTS undergoes thermal decomposition to generate active free radicals such as CH3 and SiCl3. These free radicals then undergo chemical reduction reaction with H2 to generate SiC. These SiC finally gather on the surface of the substrate to form a high-purity, high-density silicon carbide (SiC) film.
[0004] However, in the existing silicon carbide (SiC) film preparation process, since SiC grains are difficult to form on the surface of the substrate in the initial stage of deposition, the raw material utilization rate of the chemical vapor deposition process (CVD) is low (about 10%), and the internal stress of the deposited silicon carbide film is large, which has a great impact on the subsequent processing yield of the silicon carbide product; and since the crystal form matching of the silicon carbide (SiC) and the substrate is difficult to control, the bonding force between the formed silicon carbide (SiC) film and the substrate is also relatively weak. Summary of the invention
[0005] The present application first forms silicon carbide grains on the surface of the substrate, changes the shape of the silicon carbide grains through annealing, and then deposits the silicon carbide film. The flatness of the silicon carbide grains after annealing is significantly improved, which can effectively improve the deposition efficiency of the silicon carbide film, reduce the internal stress of the silicon carbide film formed by deposition, and improve the utilization rate of raw materials in the deposition process of the silicon carbide film; and the silicon carbide grains on the surface of the substrate help the silicon carbide film to be more firmly bonded to the substrate.
[0006] Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.
[0007] To achieve one, part, or all of the above objectives or other objectives, the present invention provides a deposition method for reducing stress in a silicon carbide film.
[0008] A deposition method for reducing stress in a silicon carbide film, comprising:
[0009] Step S1: providing a substrate, introducing a reaction gas to react with the substrate, and forming silicon carbide grains on the surface of the substrate;
[0010] Step S2: performing annealing treatment on the substrate with silicon carbide grains formed on the surface;
[0011] Step S3: using a chemical vapor deposition process to deposit a silicon carbide film on the surface of the substrate after the annealing treatment.
[0012] The shape of the silicon carbide grains formed on the surface of the substrate is processed by the annealing treatment to improve the flatness of the silicon carbide grains.
[0013] Placing the substrate into a reaction chamber, introducing the reaction gas, controlling the temperature of the reaction chamber to be a first temperature, and forming silicon carbide grains on the surface of the substrate;
[0014] Lowering the temperature of the reaction chamber to a second temperature for annealing;
[0015] The temperature of the reaction chamber is adjusted to rise to a third temperature to complete the deposition of the silicon carbide film.
[0016] The substrate is a graphite substrate or a silicon substrate, and different substrates correspond to different reaction gases;
[0017] The substrate is a graphite substrate, and the corresponding reaction gas is a silicon source gas;
[0018] The substrate is a silicon substrate, and the corresponding reaction gas is a carbon source gas.
[0019] The substrate is a graphite substrate, and the silicon source gas is silane;
[0020] The temperature at which silicon carbide grains are formed on the surface of the graphite substrate in step S1 is 1100-1200°C.
[0021] The substrate is a silicon substrate, and the carbon source gas is methane;
[0022] The temperature at which silicon carbide grains are formed on the surface of the silicon substrate in step S1 is 1300-1400°C.
[0023] The time for forming silicon carbide grains in step S1 is 5-10 minutes.
[0024] The annealing temperature is 400-500°C.
[0025] The annealing treatment time is not less than 5 minutes.
[0026] The chemical vapor deposition process uses methyltrichlorosilane and hydrogen as reaction gases, and the reaction temperature is 1300-1500°C.
[0027] Compared with the prior art, the beneficial effects of the present invention mainly include:
[0028] 1. The flatness of the silicon carbide grains after annealing in this application is significantly improved, which can effectively improve the deposition efficiency of the subsequent silicon carbide film and reduce the internal stress of the deposited silicon carbide film;
[0029] 2. The silicon carbide grains formed on the surface of the substrate of the present application can improve the utilization rate of raw materials in the subsequent silicon carbide film deposition process;
[0030] 3. The silicon carbide grains formed on the surface of the substrate of the present application help the silicon carbide film to be more firmly bonded to the substrate.
[0031] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0033] Figure 1 A schematic flow chart of a deposition method for reducing stress in a silicon carbide film provided in an embodiment of the present application.
[0034] Figure 2 A time-temperature relationship diagram provided for an embodiment of the present application.
[0035] Figure 3 A schematic diagram of a deposition method for reducing stress in a silicon carbide film provided in an embodiment of the present application. DETAILED DESCRIPTION
[0036] The above and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention.
[0037] The present application first forms silicon carbide grains on the surface of the substrate, changes the shape of the silicon carbide grains through annealing, and then deposits the silicon carbide film. The flatness of the silicon carbide grains after annealing is significantly improved, which can effectively improve the deposition efficiency of the silicon carbide film, reduce the internal stress of the silicon carbide film formed by deposition, and improve the utilization rate of raw materials in the deposition process of the silicon carbide film; and the silicon carbide grains on the surface of the substrate help the silicon carbide film to be more firmly bonded to the substrate.
[0038] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.
[0039] Example:
[0040] like Figure 1 As shown, a deposition method for reducing stress of a silicon carbide film comprises:
[0041] Step S1: providing a substrate, introducing a reaction gas to react with the substrate, and forming silicon carbide grains on the surface of the substrate;
[0042] Step S2: performing annealing treatment on the substrate with silicon carbide grains formed on the surface;
[0043] Step S3: using a chemical vapor deposition process to deposit a silicon carbide film on the surface of the substrate after the annealing treatment.
[0044] Specifically, step S1: firstly put the substrate into the reaction chamber, and introduce the raw material gas, and control the temperature of the reaction chamber to a first temperature ( Figure 2 1100-1200°C), the raw material gas reacts with the substrate to form silicon carbide grains on the surface of the substrate;
[0045] Step S2: Lower the temperature of the reaction chamber to a second temperature ( Figure 2 After annealing, the shape of the silicon carbide grains becomes smooth and the flatness is significantly improved.
[0046] Step S3: Adjust the temperature of the reaction chamber to a third temperature ( Figure 2 1300-1500°C as shown), a chemical vapor deposition process is used to complete the deposition of silicon carbide film on the surface of the substrate after annealing.
[0047] The substrate of the present application is a graphite substrate or a silicon substrate. Different reaction gases are introduced into different substrates. Different reaction gases react with the substrates at different first temperatures to form silicon carbide grains on the surface of the substrate.
[0048] The substrate is a graphite substrate, and the corresponding reaction gas is a silicon source gas; for example, the substrate is a graphite substrate, and the corresponding reaction gas is silane. At a temperature of 1100-1200°C, silane reacts with the graphite substrate to form silicon carbide grains on the surface of the graphite substrate. Figure 2 As shown, the time for forming silicon carbide grains in step S1 is 5-10 minutes.
[0049] Specifically, the reaction gas is silane, which decomposes under heating conditions to release silicon atoms, which combine with carbon atoms from the graphite substrate to form silicon carbide. For the formation of silicon carbide, 1100-1200°C is an ideal temperature range. Within this temperature range, the decomposition of silane and the chemical reaction between silicon and carbon can be effectively promoted, thereby forming a stable silicon carbide crystal structure.
[0050] There is good lattice matching between the graphite substrate and the silicon carbide formed on the surface of the graphite substrate, which helps to reduce stress problems caused by lattice mismatch and ensures better bonding between the graphite substrate and the silicon carbide grains; and the silicon carbide grains formed on the surface of the graphite substrate help the silicon carbide film to be more firmly bonded to the substrate.
[0051] The substrate is a silicon substrate, and the corresponding reaction gas is a carbon source gas; for example, the substrate is a silicon substrate, and the corresponding reaction gas is methane. At a temperature of 1300-1400° C., methane reacts with the silicon substrate to form silicon carbide grains on the surface of the silicon substrate.
[0052] Specifically, a prepared silicon substrate is placed in a reaction chamber, and at a temperature of 1300-1400°C, methane and other auxiliary gases (such as hydrogen H2 as a carrier gas) are introduced into the reaction chamber. Hydrogen not only helps to carry the reactants to the surface of the substrate, but also participates in the cracking process of methane, promoting its decomposition into active species. At high temperatures, methane molecules undergo thermal cracking to produce free carbon atoms and hydrogen. As methane cracks, the generated carbon atoms react with silicon atoms on the surface of the silicon substrate to form silicon carbide. By adjusting parameters such as the ratio of the reaction gas, flow rate, total pressure, and deposition time, the growth rate of silicon carbide grains can be effectively controlled.
[0053] There is good lattice matching between the silicon substrate and the silicon carbide formed on the surface of the silicon substrate, which helps to reduce stress problems caused by lattice mismatch and ensures better bonding between the silicon substrate and the silicon carbide grains; and the silicon carbide grains formed on the surface of the silicon substrate help the silicon carbide film to bond more firmly to the silicon substrate.
[0054] like Figure 3 As shown, by annealing process (such as Figure 2The silicon carbide grains 2 formed on the surface of the substrate 1 are treated with an annealing temperature of 400-500°C as shown. The annealing time should be no less than 5 minutes, which can make the shape of the silicon carbide grains 2 smooth, effectively improve the flatness of the silicon carbide grains, and help the silicon carbide film 3 to be better deposited.
[0055] Specifically, the temperature of the reaction chamber is lowered to 400-500°C for low-temperature annealing or medium-temperature annealing. Although it is not enough to induce large-scale atomic migration and lattice reconstruction, it is enough to activate the diffusion behavior of surface atoms, which enables surface atoms to move in a smaller range, fill tiny pits or remove protrusions, thereby making the grain boundaries smoother and the overall surface smoother; and low-temperature annealing helps to reduce some surface defects, such as steps, kinks and point defects, etc. The presence of these defects often increases surface roughness, and these defects can be partially healed through annealing, thereby improving surface quality; although 400-500°C is relatively low compared to high-temperature annealing, it is still enough to release some residual stress accumulated inside the material to a certain extent, and the release of stress also helps to prevent deformation of silicon carbide grains and promote a more uniform silicon carbide grain morphology.
[0056] In addition, a suitable annealing gas can be selected according to specific needs. For example, under the protection of an inert gas, additional oxidation reactions during the annealing process can be avoided.
[0057] Finally, adjust the temperature of the reaction chamber to increase the temperature (such as Figure 2 The chemical vapor deposition process shown has a reaction temperature of 1300-1500° C., uses methyltrichlorosilane and hydrogen as reaction gases in the chemical vapor deposition process, and completes the deposition of the silicon carbide film on the surface of the substrate after annealing. The reaction time is positively correlated with the thickness of the silicon carbide film.
[0058] Specifically, MTS is introduced, the temperature is raised to the reaction temperature of MTS, and a CVD reaction is carried out. Since silicon carbide grains are formed on the surface of the substrate, MTS is more likely to react, which can effectively improve the deposition efficiency of the subsequent silicon carbide film, reduce the internal stress of the deposited silicon carbide film, and improve the utilization rate of raw materials in the subsequent silicon carbide film deposition process.
[0059] Under the temperature condition of 1300-1500℃, the reaction gas (methyltrichlorosilane MTS and hydrogen H2) will undergo pyrolysis and chemical reaction to generate SiC film deposited on the surface of the substrate after annealing. Specifically, at high temperature, MTS will undergo pyrolysis reaction and decompose into silicon, carbon and other by-products; at the same time, hydrogen helps to promote the cracking of MTS, and can combine with chlorine atoms to generate hydrogen chloride (HCl), thereby removing harmful chlorine atoms from the reaction environment; the decomposed silicon and carbon atoms will recombine on the surface of the substrate to form silicon carbide; and the presence of hydrogen can not only help remove by-products (such as HCl), but also act as a carrier gas to ensure that the reactants are evenly distributed and reach the surface of the substrate; when silicon and carbon atoms meet on the surface of the substrate, they will combine to form a silicon carbide crystal structure. Due to the high energy state under high temperature conditions, these atoms can quickly find a stable position to build a continuous and dense silicon carbide film.
[0060] In addition, precise control of the ratio and total flow rate of MTS and hydrogen H2 is crucial to obtaining uniform, high-quality silicon carbide films. A higher hydrogen H2 flow rate can help remove by-products more thoroughly and maintain a clean reaction environment. The appropriate pressure level helps balance the gas diffusion rate and reaction rate. Generally, better silicon carbide film quality can be obtained under low pressure.
[0061] The present application first forms silicon carbide grains on the surface of the substrate, changes the shape of the silicon carbide grains through annealing, and then deposits the silicon carbide film. The flatness of the silicon carbide grains after annealing is significantly improved, which can effectively improve the deposition efficiency of the silicon carbide film, reduce the internal stress of the silicon carbide film formed by deposition, and improve the utilization rate of raw materials in the deposition process of the silicon carbide film; and the silicon carbide grains on the surface of the substrate help the silicon carbide film to be more firmly bonded to the substrate.
[0062] In order to facilitate the description, some common English nouns or letters used in the present invention are only used for exemplary reference rather than restrictive interpretation or specific usage, and the protection scope of the present invention should not be limited by their possible Chinese translations or specific letters.
[0063] It should also be noted that, in this document, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.
Claims
1. A deposition method for reducing stress in a silicon carbide film, characterized in that: include: Step S1: providing a substrate, introducing a reaction gas to react with the substrate, and forming silicon carbide grains on the surface of the substrate; Step S2: performing annealing treatment on the substrate with silicon carbide grains formed on the surface; Step S3: using a chemical vapor deposition process to deposit a silicon carbide film on the surface of the substrate after the annealing treatment.
2. A deposition method for reducing stress in a silicon carbide film according to claim 1, characterized in that: The shape of the silicon carbide grains formed on the surface of the substrate is processed by the annealing treatment to improve the flatness of the silicon carbide grains.
3. A deposition method for reducing stress in a silicon carbide film according to claim 1, characterized in that: Placing the substrate into a reaction chamber, introducing the reaction gas, controlling the temperature of the reaction chamber to be a first temperature, and forming silicon carbide grains on the surface of the substrate; Lowering the temperature of the reaction chamber to a second temperature for annealing; The temperature of the reaction chamber is adjusted to rise to a third temperature to complete the deposition of the silicon carbide film.
4. A deposition method for reducing stress in a silicon carbide film according to claim 1, characterized in that: The substrate is a graphite substrate or a silicon substrate, and different substrates correspond to different reaction gases; The substrate is a graphite substrate, and the corresponding reaction gas is a silicon source gas; The substrate is a silicon substrate, and the corresponding reaction gas is a carbon source gas.
5. A deposition method for reducing stress in a silicon carbide film according to claim 4, characterized in that: The substrate is a graphite substrate, and the silicon source gas is silane; The temperature at which silicon carbide grains are formed on the surface of the graphite substrate in step S1 is 1100-1200°C.
6. A deposition method for reducing stress in a silicon carbide film according to claim 4, characterized in that: The substrate is a silicon substrate, and the carbon source gas is methane; The temperature at which silicon carbide grains are formed on the surface of the silicon substrate in step S1 is 1300-1400°C.
7. A deposition method for reducing stress in a silicon carbide film according to claim 5 or 6, characterized in that: The time for forming silicon carbide grains in step S1 is 5-10 minutes.
8. The deposition method for reducing stress of a silicon carbide film according to claim 1, characterized in that: The annealing temperature is 400-500°C.
9. A deposition method for reducing stress in a silicon carbide film according to claim 8, characterized in that: The annealing treatment time is not less than 5 minutes.
10. The deposition method for reducing stress of a silicon carbide film according to claim 1, characterized in that: The chemical vapor deposition process uses methyltrichlorosilane and hydrogen as reaction gases, and the reaction temperature is 1300-1500°C.