Preparation method and chemical vapor deposition apparatus for doped silicon carbide

Abstract

This invention relates to a method for preparing doped silicon carbide and a chemical vapor deposition apparatus. The method for preparing doped silicon carbide includes: providing a mixed precursor solution containing boron; conveying the mixed precursor solution in the form of microdroplets into a reaction chamber via a bubbling method using a carrier gas; and depositing silicon carbide on the surfaces of multiple deposition supports in the reaction chamber using a chemical vapor deposition process at a preset temperature and pressure, wherein the boron element in the microdroplets is incorporated into the silicon carbide during the deposition process. This not only improves the resistivity uniformity of doped silicon carbide deposited on a single deposition support but also effectively enhances the resistivity consistency of doped silicon carbide deposited on multiple deposition supports in the reaction chamber.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for preparing doped silicon carbide and a chemical vapor deposition apparatus for preparing doped silicon carbide. Background Technology

[0002] As Moore's Law for integrated circuits gradually slows down, in the field of memory chip technology, ultra-miniaturization of linewidth in DRAM (Dynamic Random Access Memory) manufacturing processes and ultra-high integration of 3D NAND (3D NAND Flash Memory) have become the main directions for advanced process development. These technological advancements place higher demands on plasma etching processes, primarily manifested in the continuous increase in the power and energy required for etching. This places more stringent requirements on the performance of key components within plasma etching equipment (such as focusing rings and electrodes).

[0003] Silicon carbide (SiC), as a third-generation semiconductor material, possesses excellent resistance to plasma etching, high thermal conductivity, high temperature resistance, oxidation resistance, wear resistance, and corrosion resistance. SiC components fabricated using solid-state chemical vapor deposition (also known as Solid CVD) offer advantages such as long service life and low particulate contamination, making them key components in plasma etching equipment used in advanced integrated circuit manufacturing processes. The resistivity of SiC components fabricated using Solid CVD needs to be adjusted according to different application scenarios to meet various practical requirements. Currently, the mainstream resistivity ranges of SiC materials are divided into: low resistivity (<0.1 Ω·cm), medium resistivity (1 Ω·cm~25 Ω·cm), and high resistivity (>100 Ω·cm). With the continuous iteration of integrated circuit manufacturing technology, the requirements for the resistivity control precision of SiC components are constantly increasing. Especially for focusing ring components used to adjust the uniformity of wafer edge processes, their resistivity directly affects the coupling electric field around the wafer. To ensure the stability of the plasma etching process, the resistivity range requirements for silicon carbide components used in the focusing ring are continuously tightened. In particular, the target resistivity of medium resistivity silicon carbide components must be strictly controlled within 1 Ω·cm to 5 Ω·cm, and the target resistivity of high resistivity silicon carbide components must be strictly controlled within 1000 Ω·cm to 5000 Ω·cm.

[0004] Currently, the industry primarily uses chemical vapor deposition (CVD) to prepare silicon carbide, incorporating nitrogen doping during the deposition process to control its resistivity. However, in mass production scenarios, large-scale CVD equipment grows dozens to hundreds of silicon carbide wafers simultaneously in the same batch, making precise control of the flow field uniformity and doping uniformity within the CVD chamber extremely challenging. Especially when preparing medium- and high-resistivity silicon carbide, the required nitrogen doping dosage is very low, and even minor fluctuations in process parameters or deviations in the growth environment can cause resistivity drift in the finished product. Therefore, existing processes struggle to accurately and stably control the resistivity of large batches of silicon carbide within a single batch, failing to meet the high resistivity uniformity requirements of current advanced processes for silicon carbide components. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a method for preparing doped silicon carbide and a chemical vapor deposition apparatus for preparing doped silicon carbide in order to solve at least one problem existing in the background art.

[0006] In a first aspect, embodiments of the present invention provide a method for preparing doped silicon carbide, the method comprising: Provide a mixed precursor solution containing boron; The mixed precursor solution is delivered into the reaction chamber in the form of microdroplets using a carrier gas via bubbling. Silicon carbide is deposited on the surfaces of multiple deposition carriers in the reaction chamber at a preset temperature and pressure using a chemical vapor deposition process, and boron in the microdroplets is incorporated into the silicon carbide during the deposition process.

[0007] In the above technical solution, a mixed precursor solution with quantitative boron doping is transported to the reaction chamber in the form of microdroplets using a carrier gas. When silicon carbide is deposited on the surface of multiple deposition carriers through chemical vapor deposition, the boron element uniformly distributed in the microdroplets will achieve precise and quantitative in-situ doping as the precursor decomposes and grows silicon carbide at high temperature. In this way, not only can the resistivity uniformity of the doped silicon carbide deposited on a single deposition carrier be improved, but the resistivity consistency of the doped silicon carbide deposited on multiple deposition carriers in the reaction chamber can also be effectively improved.

[0008] In conjunction with the first aspect of the invention, in an optional embodiment, providing the mixed precursor solution containing boron comprises: The first precursor liquid and the second precursor liquid containing boron are respectively delivered to a mixer at a first preset flow rate and a second preset flow rate for mixing to obtain the mixed precursor solution.

[0009] In the above technical solution, the boron content in the mixed precursor solution can be flexibly and conveniently adjusted according to the target resistivity of the silicon carbide to be prepared. This means that the boron doping dosage can be easily controlled before the mixed precursor solution is transported to the reaction chamber in the form of microdroplets using a carrier gas. Therefore, the resistivity of silicon carbide can be controlled without changing the flow rate of the carrier gas containing microdroplets into the reaction chamber. The process exhibits strong stability and controllability, improving the resistivity drift problem caused by process fluctuations. This ensures better uniformity of the resistivity of the prepared doped silicon carbide and allows for accurate control of the resistivity value within the target range. The above technical solution is even more advantageous if it is necessary to manufacture silicon carbide with a stepped or continuous gradient resistivity distribution along the thickness direction.

[0010] In conjunction with the first aspect of the present invention, in an optional embodiment, the first precursor liquid and the second precursor liquid each independently comprise one or more of monomethyltrichlorosilane, dimethyldichlorosilane, and trimethylmonochlorosilane.

[0011] In the above technical solutions, the precursor liquid has advantages such as silicon and carbon homology, easy adjustment of the ratio, and easy removal of impurities, which is conducive to the preparation of high-quality doped silicon carbide.

[0012] In conjunction with the first aspect of the present invention, in an optional embodiment, the boron content in the second precursor liquid is 75ppm to 85ppm.

[0013] In the above technical solution, the boron content in the second precursor liquid is controlled within the above range, which facilitates the uniform distribution of boron in the second precursor liquid. It also allows for the adjustment of the flow rates of the first and second precursor liquids within a wider adjustment range to control the boron content in the mixed precursor solution at the required level, thereby controlling the resistivity of the deposited doped silicon carbide within the target range.

[0014] In conjunction with the first aspect of the present invention, in an optional embodiment, the preset temperature is 1300℃~1450℃, and the preset pressure is 500Torr~760Torr.

[0015] In the above technical solution, controlling the temperature and pressure for depositing doped silicon carbide within the aforementioned range is beneficial for ensuring the quality of the deposited doped silicon carbide while also taking into account the deposition efficiency.

[0016] Secondly, embodiments of the present invention provide a chemical vapor deposition apparatus for preparing doped silicon carbide, the apparatus comprising: A liquid supply device for providing a mixed precursor solution containing boron; The reaction chamber is used to accommodate multiple deposition carriers; The bubbler has a liquid inlet connected to the liquid supply device, an air inlet connected to the carrier gas supply system, and an air outlet connected to the reaction chamber. It is used to transport the mixed precursor solution supplied by the liquid supply device into the reaction chamber in the form of microdroplets using the carrier gas supplied by the carrier gas supply system, so as to deposit boron-doped silicon carbide on the deposition carrier.

[0017] In the above technical solution, the bubbler can use the carrier gas supplied by the carrier gas supply system to transport the mixed precursor solution with quantitative boron doping supplied by the liquid supply device into the reaction chamber in the form of microdroplets. When silicon carbide is deposited on the surfaces of multiple deposition carriers in the reaction chamber, the boron element uniformly distributed in the microdroplets will achieve precise and quantitative in-situ doping as the precursor decomposes and grows silicon carbide at high temperature. In this way, not only can the resistivity uniformity of the doped silicon carbide deposited on a single deposition carrier be improved, but the resistivity consistency of the doped silicon carbide deposited on multiple deposition carriers in the reaction chamber can also be effectively improved.

[0018] In conjunction with a second aspect of the invention, in an optional embodiment, the liquid supply device includes: mixer; The first liquid storage tank is used to store the first precursor liquid; The first liquid supply pipeline is connected at one end to the first liquid storage tank and at the other end to the mixer; A first metering pump, connected to the first liquid supply pipeline, is used to regulate the flow rate of the first precursor liquid supplied to the mixer; The second storage tank is used to store the second precursor liquid containing boron. The second liquid supply pipeline is connected at one end to the second liquid storage tank and at the other end to the mixer; A second metering pump, connected to the second liquid supply pipeline, is used to regulate the flow rate of the second precursor liquid supplied to the mixer.

[0019] In the above technical solution, the flow rates of the first and second precursor liquids supplied to the mixer can be adjusted by regulating the setting parameters of the first and second metering pumps. This allows for flexible and convenient adjustment of the boron content in the mixed precursor solution based on the target resistivity of the silicon carbide to be prepared. Specifically, the boron doping dosage can be easily controlled before the mixed precursor solution is delivered to the reaction chamber in the form of microdroplets using a carrier gas. This allows for control of the silicon carbide resistivity without changing the flow rate of the carrier gas containing microdroplets into the reaction chamber. The process exhibits strong stability and controllability, mitigating the silicon carbide resistivity drift caused by process fluctuations. This ensures better uniformity of the resistivity of the doped silicon carbide and allows for accurate control of the resistivity value within the target range. The above technical solution is even more advantageous if it is necessary to manufacture silicon carbide with a stepped or continuous gradient resistivity distribution along the thickness direction.

[0020] In conjunction with a second aspect of the present invention, in an optional embodiment, the second storage tank is provided with a stirrer for stirring the second precursor liquid.

[0021] In the above technical solution, the stirring action of the stirrer can ensure the uniform distribution of boron in the second precursor liquid, which is conducive to more accurate control of the boron content in the mixed precursor, and thus can more accurately control the resistivity of the doped silicon carbide.

[0022] In conjunction with a second aspect of the invention, in an optional embodiment, the stirrer is made of polytetrafluoroethylene and / or perfluoroalkoxy resin.

[0023] In the above technical solution, the agitator material has strong corrosion resistance and high purity. Compared with materials such as stainless steel, it can reduce the problem of impurity atoms precipitating into the second precursor liquid, avoid contaminating the second precursor liquid, and ensure the service life of the agitator.

[0024] In conjunction with a second aspect of the invention, in an optional embodiment, the apparatus further includes: The gas distribution structure has an inlet end connected to the bubbler and multiple outlet ends connected to the reaction chamber, which is used to deliver the carrier gas carrying the micro-droplets to the reaction chamber in multiple ways.

[0025] The above-mentioned technical solution enables the carrier gas, including microdroplets, to be dispersed more quickly and evenly throughout the reaction chamber.

[0026] The method for preparing doped silicon carbide and the chemical vapor deposition apparatus for preparing doped silicon carbide provided in this invention have the following beneficial effects: (1) Using a carrier gas, a mixed precursor solution with quantitative boron doping is transported to the reaction chamber in the form of microdroplets. When silicon carbide is deposited on the surface of multiple deposition carriers by chemical vapor deposition, the boron element uniformly distributed in the microdroplets will achieve precise and quantitative in-situ doping as the precursor decomposes at high temperature to grow silicon carbide. In this way, not only can the resistivity uniformity of the doped silicon carbide deposited on a single deposition carrier be improved, but the resistivity consistency of the doped silicon carbide deposited on multiple deposition carriers in the reaction chamber can also be effectively improved.

[0027] (2) The boron content in the mixed precursor solution can be flexibly and conveniently adjusted according to the target resistivity of the silicon carbide to be prepared. That is, the boron doping dosage can be easily controlled before the mixed precursor solution is transported to the reaction chamber in the form of microdroplets using a carrier gas. Thus, the resistivity of silicon carbide can be controlled without changing the flow rate of the carrier gas containing microdroplets into the reaction chamber. The process has strong stability and controllability, which can improve the problem of silicon carbide resistivity drift caused by process fluctuations. This can better ensure the resistivity uniformity of the prepared doped silicon carbide and accurately control the resistivity value within the target range. It is even more advantageous if it is necessary to manufacture silicon carbide with a stepped or continuous gradient resistivity distribution in the thickness direction.

[0028] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic flowchart of a method for preparing doped silicon carbide according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a chemical vapor deposition apparatus for preparing doped silicon carbide, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the chemical vapor deposition apparatus used in the examples and comparative examples for preparing doped silicon carbide. Detailed Implementation

[0030] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0031] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without one or more of these details. In other instances, to avoid obscuring the invention, some technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0032] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0033] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And when a second element, component, area, layer, or portion is discussed, it does not imply that the first element, component, area, layer, or portion necessarily exists in this invention.

[0034] Spatial relation terms such as “below,” “under,” “below,” “below,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0036] To fully understand this invention, detailed steps and structures will be presented in the following description to illustrate the technical solution of this invention. Preferred embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0037] In existing technologies, when preparing silicon carbide using chemical vapor deposition (CVD), a doping gas (such as nitrogen) is introduced during the deposition process to control the resistivity of silicon carbide. However, for large-scale CVD apparatuses, where dozens to hundreds of silicon carbide wafers are grown simultaneously in the same batch, precise control of the uniformity of the flow field and doping within the CVD chamber presents significant technical challenges. This is especially true when preparing medium- and high-resistivity silicon carbide, where the required nitrogen doping dosage is very low, and even slight deviations or fluctuations in the deposition environment can cause resistivity drift. Furthermore, due to the large size of the deposition chamber, nitrogen and the precursor are prone to spatial stratification due to gravity or flow field influences, with nitrogen more likely to focus at the bottom of the chamber, resulting in lower resistivity of the silicon carbide at the bottom. To address this issue, some organizations have attempted optimizations such as reducing the volume of the deposition chamber, isolating and partitioning the chamber, or adding flow field improvement devices. However, these methods all suffer from increased difficulty in controlling process stability and higher manufacturing costs, making them unsuitable for mass production. Furthermore, in traditional silicon carbide chemical vapor deposition (CVD) processes, switching the target resistivity range typically relies on adjusting the flow rate of the dopant gas. However, adjusting the dopant gas flow rate inevitably leads to changes in the total gas flow and gas ratio within the deposition chamber, requiring recalibration of all process parameters. This makes it impossible to effectively control the product resistivity while maintaining process stability.

[0038] Based on this, embodiments of the present invention provide a method for preparing doped silicon carbide, please refer to... Figure 1 The method for preparing doped silicon carbide in this embodiment of the invention includes: Step S101: Provide a mixed precursor solution containing boron. Step S102: The mixed precursor solution is delivered into the reaction chamber in the form of microdroplets using a carrier gas via bubbling. Step S103: Under preset temperature and preset pressure, silicon carbide is deposited on the surface of multiple deposition carriers in the reaction chamber by chemical vapor deposition process, and boron element in microdroplets is incorporated into silicon carbide during the silicon carbide deposition process.

[0039] In this invention, a mixed precursor solution with quantitative boron doping is transported to the reaction chamber in the form of microdroplets using a carrier gas. When silicon carbide is deposited on the surface of multiple deposition carriers through chemical vapor deposition, the boron element uniformly distributed in the microdroplets will achieve precise and quantitative in-situ doping as the precursor decomposes and grows silicon carbide at high temperature. In this way, not only can the resistivity uniformity of the doped silicon carbide deposited on a single deposition carrier be improved, but the resistivity consistency of the doped silicon carbide deposited on multiple deposition carriers in the reaction chamber (especially multiple deposition carriers stacked at intervals in high and low orientations) can also be effectively improved.

[0040] In step S101, providing a mixed precursor solution containing boron may include: feeding a first precursor liquid and a second precursor liquid containing boron into a mixer at a first preset flow rate and a second preset flow rate, respectively, for mixing to obtain a mixed precursor solution.

[0041] In existing technologies, adjusting the resistivity of the prepared silicon carbide requires adjusting the flow rate of the dopant gas introduced into the reaction chamber, inevitably causing process fluctuations and affecting doping uniformity and controllability. In this embodiment, by mixing the first precursor liquid and the second precursor liquid containing boron at a preset flow rate in a mixer, the boron content in the mixed precursor solution can be flexibly and conveniently adjusted according to the target resistivity of the silicon carbide to be prepared. This means that the boron doping dosage can be easily controlled before the mixed precursor solution is delivered to the reaction chamber in the form of microdroplets using a carrier gas. Therefore, the resistivity of silicon carbide can be controlled without changing the flow rate of the carrier gas containing microdroplets introduced into the reaction chamber. This process offers strong stability and controllability, improving the resistivity drift problem caused by process fluctuations and ensuring better uniformity of the resistivity of the prepared doped silicon carbide, while accurately controlling the resistivity value within the target range. The preparation method in this embodiment is even more advantageous if it is necessary to manufacture silicon carbide with a stepped or continuous gradient resistivity distribution along the thickness direction.

[0042] In this embodiment, the first precursor liquid and the second precursor liquid may each independently include one or more of monomethyltrichlorosilane (CH3SiCl3), dimethyldichlorosilane ((CH3)2SiCl2), and trimethylchlorosilane ((CH3)3SiCl). Exemplarily, the first precursor liquid and the second precursor liquid may each independently be one or more of CH3SiCl3, (CH3)2SiCl2, and (CH3)3SiCl.

[0043] The precursor liquids of the above types have advantages such as silicon and carbon homology, easy ratio adjustment, and easy removal of impurities, which are conducive to the preparation of high-quality doped silicon carbide.

[0044] The first precursor liquid and the second precursor liquid can be the same or different. In some specific embodiments, the first precursor liquid and the second precursor liquid can be the same. This helps to improve the consistency of the mixed precursor solution, thereby further improving the stability and controllability of the process, and thus better ensuring the quality of the doped silicon carbide obtained.

[0045] Preferably, the first precursor liquid and the second precursor liquid are methyltrichlorosilane. methyltrichlorosilane has a silicon-to-carbon ratio (1:1) that matches silicon carbide and a high chlorine content, which is beneficial for obtaining high-quality silicon carbide with fewer defects.

[0046] The boron content in the second precursor liquid can be 75ppm to 85ppm, for example, 75ppm, 80ppm, 85ppm or any value between any two of the above ranges.

[0047] By controlling the boron content in the second precursor liquid within the aforementioned range, it is possible to achieve a uniform distribution of boron in the second precursor liquid. It also allows for adjustment of the flow rates of the first and second precursor liquids within a wider range to control the boron content in the mixed precursor solution at the desired level, thereby controlling the resistivity of the deposited doped silicon carbide within the target range.

[0048] Boron in the second precursor liquid can be introduced by adding a boron-containing dopant (such as boron powder).

[0049] In some embodiments, the boron in the second precursor liquid can be boron naturally present in the precursor liquid raw material. During the preparation of the precursor liquid raw material, a certain amount of boron may remain. Normally, this boron is removed through purification, for example, the boron content in the first precursor liquid is controlled to be below 0.2 ppm. However, since the second precursor liquid in this invention requires boron doping, the manufacturer can control the preparation process to keep the boron content in the precursor liquid raw material within the required range (e.g., 75 ppm to 85 ppm). This allows the precursor liquid raw material to be used directly as the second precursor liquid. This not only saves the additional step of doping boron into the precursor liquid raw material, reducing costs, but also better ensures the uniformity of boron dispersion in the second precursor liquid, thereby improving the resistivity uniformity of the deposited doped silicon carbide.

[0050] In step S102, the mixed precursor solution is transported into the reaction chamber in the form of microdroplets using a carrier gas via bubbling.

[0051] In the actual preparation process, a bubbler and a carrier gas supply system can be used to deliver the mixed precursor solution into the reaction chamber in the form of microdroplets. The inlet of the bubbler can be connected to the mixer described above. The carrier gas can be, for example, hydrogen. By controlling the flow rate of the carrier gas, the flow rate of the carrier gas containing microdroplets output from the bubbler can be controlled.

[0052] The aforementioned microdroplets refer to minute liquid units formed through bubbling and transported by a carrier gas. They can be understood as tiny droplets suspended in the gas phase.

[0053] In some specific embodiments, the flow rate of the carrier gas containing microdroplets output from the bubbler can be 150 SLPM to 230 SLPM, for example, 150 SLPM, 160 SLPM, 170 SLPM, 180 SLPM, 190 SLPM, 200 SLPM, 210 SLPM, 220 SLPM, 230 SLPM or any value between any two of the above ranges; thereby controlling the flow rate of the carrier gas containing microdroplets introduced into the reaction chamber within a suitable range to balance the deposition quality and deposition efficiency of doped silicon carbide.

[0054] In step S103, silicon carbide is deposited on the surface of multiple deposition carriers in the reaction chamber by chemical vapor deposition at a preset temperature and pressure. Boron in the microdroplets is incorporated into the silicon carbide during the deposition process.

[0055] The preset temperature can be between 1300℃ and 1450℃, for example, it can be 1300℃, 1350℃, 1400℃, 1450℃, or any value between any two of the above ranges. The preset pressure can be between 500 Torr and 760 Torr, for example, it can be 500 Torr, 550 Torr, 600 Torr, 650 Torr, 700 Torr, 760 Torr, or any value between any two of the above ranges.

[0056] Controlling the temperature and pressure for depositing doped silicon carbide within the aforementioned range helps to ensure both the quality of the deposited doped silicon carbide and the deposition efficiency.

[0057] In actual fabrication processes, a reaction chamber can accommodate one or more rows of deposition supports, and each row of deposition supports can include multiple deposition supports stacked at intervals. The material of the deposition supports can be high-purity graphite. Boron elements uniformly distributed in the microdroplets achieve precise and quantitative in-situ doping during the high-temperature decomposition and growth of silicon carbide from the precursor. This not only improves the resistivity uniformity of doped silicon carbide deposited on a single deposition support but also effectively improves the resistivity consistency of doped silicon carbide deposited on multiple deposition supports within the reaction chamber.

[0058] This invention also provides a chemical vapor deposition apparatus for preparing doped silicon carbide, please refer to... Figure 2 The device includes: a liquid supply device for providing a mixed precursor solution containing boron; a reaction chamber 13 for accommodating multiple deposition supports 14; and a bubbler 7, with its liquid inlet connected to the liquid supply device, its gas inlet connected to a carrier gas supply system 8, and its gas outlet connected to the reaction chamber 13, for using the carrier gas supplied by the carrier gas supply system 8 to transport the mixed precursor solution supplied by the liquid supply device in the form of microdroplets into the reaction chamber 13, so as to deposit boron-doped silicon carbide on the deposition supports 14.

[0059] In the aforementioned apparatus, the bubbler 7 utilizes the carrier gas supplied by the carrier gas supply system 8 to transport the quantitatively doped boron-containing mixed precursor solution supplied by the liquid supply device into the reaction chamber 13 in the form of microdroplets. During silicon carbide deposition on the surfaces of multiple deposition supports 14 within the reaction chamber 13, the boron element, uniformly distributed in the microdroplets, achieves precise and quantitative in-situ doping as the precursor decomposes and grows silicon carbide at high temperatures. This not only improves the resistivity uniformity of the doped silicon carbide deposited on a single deposition support 14 but also effectively improves the resistivity uniformity of multiple deposition supports 14 within the reaction chamber 13 (such as…). Figure 2 The resistivity of the doped silicon carbide deposited on the multiple deposition carriers 14) arranged in a spaced-out stack is consistent.

[0060] A reaction chamber 13 can typically accommodate one or more rows of deposition supports, and each row of deposition supports can include multiple deposition supports 14 stacked at intervals. The material of the deposition supports 14 can be, for example, high-purity graphite. The deposition supports 14 can also be referred to as graphite substrates.

[0061] In some embodiments, please refer to Figure 2 The liquid supply device may include: a mixer 6; a first storage tank 4 for storing a first precursor liquid; a first supply pipe 19, one end of which is connected to the first storage tank 4 and the other end of which is connected to the mixer 6; a first metering pump 5 connected to the first supply pipe 19 for regulating the flow rate of the first precursor liquid supplied to the mixer 6; a second storage tank 1 for storing a second precursor liquid containing boron; a second supply pipe 20, one end of which is connected to the second storage tank 1 and the other end of which is connected to the mixer 6; and a second metering pump 2 connected to the second supply pipe 20 for regulating the flow rate of the second precursor liquid supplied to the mixer 6.

[0062] The chemical vapor deposition apparatus in this embodiment allows for adjustment of the flow rates of the first and second precursor liquids supplied to the mixer 6 by regulating the setting parameters of the first metering pump 5 and the second metering pump 2. This enables flexible and convenient adjustment of the boron content in the mixed precursor solution based on the target resistivity of the silicon carbide to be prepared. Specifically, the boron doping dosage can be easily controlled before the mixed precursor solution is delivered to the reaction chamber 13 in the form of microdroplets using a carrier gas. This allows for control of the silicon carbide resistivity without changing the flow rate of the carrier gas containing microdroplets into the reaction chamber 13. The process exhibits strong stability and controllability, mitigating the silicon carbide resistivity drift problem caused by process fluctuations. This ensures better uniformity of the resistivity of the prepared doped silicon carbide and allows for accurate control of the resistivity value within the target range. The preparation method in this embodiment is even more advantageous if a stepped or continuous gradient distribution of resistivity is required along the thickness direction.

[0063] Alternatively, please refer to Figure 2 The second storage tank 1 can be equipped with a stirrer 3 for stirring the second precursor liquid. In this way, the stirring action of the stirrer 3 can ensure the uniform distribution of boron in the second precursor liquid, which is conducive to more accurate control of the boron content in the mixed precursor, and thus can more accurately control the resistivity of the doped silicon carbide.

[0064] For example, the agitator 3 may be made of polytetrafluoroethylene (PTFE) and / or perfluoroalkoxy resin (PFA).

[0065] PTFE and PFA have strong corrosion resistance and high purity. Compared with materials such as stainless steel, they can reduce the problem of impurity atoms precipitating into the second precursor liquid, avoid contaminating the second precursor liquid, and ensure the service life of the stirrer 3.

[0066] The mixer 6 in the liquid supply device can be a static mixer. Static mixers may include, for example, spiral blade type, corrugated blade type, orifice plate type, baffle type, etc. This application does not make specific limitations.

[0067] Please refer to Figure 2 The outlet of mixer 6 can be connected to the inlet of bubbler 7, thereby conveying the mixed precursor solution to bubbler 7. The first and second precursor liquids can be fully mixed in mixer 6 before being conveyed to bubbler 7, ensuring both the uniform distribution of boron in the mixed precursor solution and the stability of bubbler 7 operation.

[0068] Of course, the present invention does not exclude the case where a mixer is not set separately. In this case, the bubbler 7 can be used as a mixer, that is, the first precursor liquid and the second precursor liquid can be introduced into the bubbler 7 at a preset flow rate.

[0069] For some specific implementation methods, please refer to Figure 2 The inlet of the bubbler 7 can be connected to the carrier gas supply system 8 via a gas supply pipe 21. A flow meter 9 can be installed on the gas supply pipe 21 to regulate the flow rate of the carrier gas entering the bubbler 7, thereby controlling the flow rate of the carrier gas containing micro-droplets output from the bubbler 7. The outlet of the bubbler 7 can be connected to the reaction chamber 13 via an outlet pipe 22, thereby delivering the carrier gas containing micro-droplets to the reaction chamber 13. A flow meter 10 can be installed on the outlet pipe 22 to monitor the flow rate of the carrier gas containing micro-droplets.

[0070] In the actual fabrication process, the flow rate of the carrier gas introduced into the bubbler 7 can be adjusted by the flow controller 9, thereby controlling the flow rate of the carrier gas containing microdroplets within a suitable range, thus ensuring the deposition quality and efficiency of the doped silicon carbide. Specifically, the flow controller 9 can be a mass flow controller. The flow meter 10 can also be a mass flow meter.

[0071] In some embodiments, please refer to Figure 2 The chemical vapor deposition apparatus may also include: a gas distribution structure 11, with an inlet end connected to a bubbler 7 and multiple outlet ends connected to a reaction chamber 13, for distributing carrier gas carrying microdroplets to the reaction chamber 13 in multiple ways.

[0072] like Figure 2 As shown, the gas distribution structure 11 includes multiple gas distribution pipes 111, and the reaction chamber 13 includes multiple air inlets 12, with each gas distribution pipe 111 connected to a single air inlet 12. This allows the carrier gas, including microdroplets, to be dispersed more quickly and uniformly throughout the reaction chamber 13, thereby improving the growth efficiency and doping uniformity of doped silicon carbide.

[0073] Furthermore, the arrangement of the multiple air inlets 12 can be adapted to the stacked arrangement of the multiple deposition carriers 14. For example, as Figure 2 As shown, multiple deposition carriers 14 are stacked at intervals on the rotating shaft 15, and multiple air inlets 12 can be arranged along the axial direction of the rotating shaft 15.

[0074] Please refer to Figure 2 The chemical vapor deposition apparatus also includes an exhaust port 16. The exhaust port 16 is used to discharge unreacted gases and reaction byproducts from the reaction chamber 13, maintain stable chamber pressure and uniform airflow, and ensure deposition quality and equipment safety.

[0075] The technical solution and beneficial effects of the present invention will be further explained below with reference to several embodiments and comparative examples.

[0076] The structures of the chemical vapor deposition apparatus used in the examples and comparative examples for preparing doped silicon carbide are as follows: Figure 3 As shown. Figure 3 Chemical vapor deposition apparatus and Figure 2 The difference in the chemical vapor deposition apparatus is that a nitrogen supply system 17 and a nitrogen flow controller 18 are added. The nitrogen supply system 17 is connected to the output pipe 22 and is used to introduce nitrogen into the reaction chamber 13, thereby facilitating the preparation of doped silicon carbide by introducing nitrogen.

[0077] All embodiments and comparative examples used the same chemical vapor deposition chamber environment, and the reaction chamber was equipped with the same 3-axis 15-layer graphite deposition carrier (the outer diameter of a single deposition carrier is 370 mm, the inner diameter is 240 mm, and the thickness is 5 mm).

[0078] Example 1 In this embodiment, doped silicon carbide with a target resistivity of 1 Ω·cm to 5 Ω·cm is prepared. The preparation method of doped silicon carbide includes: Step S1: Add the first precursor liquid (methyltrichlorosilane liquid, boron content <0.2ppm) and the second precursor liquid (methyltrichlorosilane liquid, boron content 80±5ppm) to the first storage tank 4 and the second storage tank 1 respectively to 80% liquid level. The boron content is measured by ICP-MS (inductively coupled plasma mass spectrometry). Step S2: The reaction chamber 13 is evacuated to a vacuum level below 0.01 Torr, then heated to 1350°C, and hydrogen is introduced to increase the chamber pressure to 760 Torr. The second and first precursor liquids are introduced in a mass ratio of 36% and 64% respectively through coordinated control of the second metering pump 2 and the first metering pump 5. After thorough mixing through the mixer 6, the mixture is introduced into the bubbler 7 at a flow rate of 5 kg / h. The flow rate of the flow meter 10 is controlled by the flow controller 9 to be 180 SLPM, and the nitrogen flow controller 18 is shut off to prevent nitrogen from entering. After 40 hours of deposition, doped silicon carbide is obtained.

[0079] Example 2 In this embodiment, doped silicon carbide with a target resistivity of 1000 Ω·cm to 5000 Ω·cm is prepared. The preparation method of doped silicon carbide is basically the same as that in the previous embodiment, except that: By coordinating the control of the second metering pump 2 and the first metering pump 5, the second precursor liquid and the first precursor liquid are introduced into the mixer 6 at a mass ratio of 3% and 97%, respectively.

[0080] Comparative Example 1 In this comparative example, doped silicon carbide with a target resistivity of 1 Ω·cm to 5 Ω·cm was prepared. The preparation method of the doped silicon carbide differs from that in Example 1 in that: The first precursor liquid was introduced into the mixer by controlling the first metering pump 5, while the second metering pump 2 was shut off to prevent the introduction of the second precursor liquid. Nitrogen gas at a flow rate of 0.49 SLPM was introduced into the reaction chamber through the nitrogen supply system 17 and the nitrogen flow controller 18. Other process conditions were the same as in Example 1. After deposition for 40 hours, doped silicon carbide was obtained.

[0081] Comparative Example 2 In this comparative example, doped silicon carbide with a target resistivity of 1000 Ω·cm to 5000 Ω·cm was prepared. The preparation method of doped silicon carbide is basically the same as that of Comparative Example 1, with the following differences: The flow rate of nitrogen introduced into the reaction chamber is adjusted to 0.053 SLPM by means of nitrogen supply system 17 and nitrogen flow controller 18.

[0082] The doped silicon carbide deposited on a 3-axis 15-layer graphite deposition carrier in each embodiment and comparative example was taken out. Resistivity tests were performed on the doped silicon carbide deposited on the 2nd, 5th, 8th, 11th, and 14th layers of the graphite deposition carrier, in a bottom-up order. Specifically, 15 pieces of doped silicon carbide were tested in each embodiment and comparative example. A four-probe resistivity meter was used to measure the resistivity of the upper and lower surfaces of each doped silicon carbide piece. Specifically, the annular doped silicon carbide sample was divided into three concentric rings (inner, middle, and outer) at equal intervals along the radial direction. Eight test points were evenly distributed along the circumference at the midpoint of each ring, and the resistivity was measured at each point. A total of 24 points were tested on a single side of each sample. The resistivity at each test point was recorded, the measured resistivity range was statistically analyzed, and the resistivity target achievement rate was calculated. The resistivity target achievement rate is the percentage of test points where the measured resistivity is equal to the target resistivity. In addition, the resistivity change rate was calculated as follows: the absolute value of the difference between the average resistivity of the outer ring and the average resistivity of the inner ring was divided by the average resistivity of the inner ring, and then multiplied by 100%. This value characterizes the resistivity uniformity of the sample under test. In each embodiment and comparative example, the maximum resistivity change rate of the 15 doped silicon carbide pieces was recorded as the resistivity change rate of the doped silicon carbide prepared in that embodiment or comparative example. The test results are shown in Table 1.

[0083] Table 1

[0084] As can be seen from the data in Table 1, compared with Comparative Examples 1 and 2, the resistivity target achievement rate of the doped silicon carbide prepared in Examples 1 and 2 is significantly improved, and the resistivity change rate is significantly reduced, that is, the resistivity uniformity is significantly improved. This indicates that, compared with the preparation of doped silicon carbide by introducing nitrogen doping gas, the preparation method of doped silicon carbide provided by the present invention can not only improve the resistivity uniformity of doped silicon carbide deposited on a single deposition carrier, but also effectively improve the resistivity consistency of doped silicon carbide deposited on multiple deposition carriers in the reaction chamber (especially multiple deposition carriers stacked at intervals in high and low orientations), and is applicable to the preparation of doped silicon carbide with various target resistivity ranges.

[0085] It should be noted that the embodiments of the method for preparing doped silicon carbide provided by the present invention and the embodiments of the chemical vapor deposition apparatus for preparing doped silicon carbide belong to the same concept; the technical features in the technical solutions described in each embodiment can be arbitrarily combined without conflict. However, it should be further noted that the combination of technical features of the chemical vapor deposition apparatus for preparing doped silicon carbide provided by the embodiments of the present invention can already solve the technical problem to be solved by the present invention; therefore, the chemical vapor deposition apparatus for preparing doped silicon carbide provided by the embodiments of the present invention is not limited to the method for preparing doped silicon carbide provided by the embodiments of the present invention.

[0086] It should be understood that the above embodiments are exemplary and not intended to encompass all possible implementations. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of the present invention and do not limit the scope of protection of this patent.

Claims

1. A method for producing a doped silicon carbide, characterized by, The method includes: Provide a mixed precursor solution containing boron; The mixed precursor solution is delivered into the reaction chamber in the form of microdroplets using a carrier gas via bubbling. Silicon carbide is deposited on the surfaces of multiple deposition carriers in the reaction chamber at a preset temperature and pressure using a chemical vapor deposition process, and boron in the microdroplets is incorporated into the silicon carbide during the deposition process.

2. The method for preparing doped silicon carbide according to claim 1, characterized in that, The provision of the mixed precursor solution containing boron includes: The first precursor liquid and the second precursor liquid containing boron are respectively delivered to a mixer at a first preset flow rate and a second preset flow rate for mixing to obtain the mixed precursor solution.

3. The method for preparing doped silicon carbide according to claim 2, characterized in that, The first precursor liquid and the second precursor liquid each independently include one or more of monomethyltrichlorosilane, dimethyldichlorosilane, and trimethylmonochlorosilane.

4. The method for preparing doped silicon carbide according to claim 2, characterized in that, The boron content in the second precursor liquid is 75ppm to 85ppm.

5. The method for preparing doped silicon carbide according to any one of claims 1-4, characterized in that, The preset temperature is 1300℃~1450℃, and the preset pressure is 500Torr~760Torr.

6. A chemical vapor deposition apparatus for preparing doped silicon carbide, characterized in that, The device includes: A liquid supply device for providing a mixed precursor solution containing boron; The reaction chamber is used to accommodate multiple deposition carriers; The bubbler has a liquid inlet connected to the liquid supply device, an air inlet connected to the carrier gas supply system, and an air outlet connected to the reaction chamber. It is used to transport the mixed precursor solution supplied by the liquid supply device into the reaction chamber in the form of microdroplets using the carrier gas supplied by the carrier gas supply system, so as to deposit boron-doped silicon carbide on the deposition carrier.

7. The chemical vapor deposition apparatus for preparing doped silicon carbide according to claim 6, characterized in that, The liquid supply device includes: mixer; The first liquid storage tank is used to store the first precursor liquid; The first liquid supply pipeline is connected at one end to the first liquid storage tank and at the other end to the mixer; A first metering pump, connected to the first liquid supply pipeline, is used to regulate the flow rate of the first precursor liquid supplied to the mixer; The second storage tank is used to store the second precursor liquid containing boron. The second liquid supply pipeline is connected at one end to the second liquid storage tank and at the other end to the mixer; A second metering pump, connected to the second liquid supply pipeline, is used to regulate the flow rate of the second precursor liquid supplied to the mixer.

8. The chemical vapor deposition apparatus for preparing doped silicon carbide according to claim 7, characterized in that, The second storage tank is equipped with a stirrer for stirring the second precursor liquid.

9. The chemical vapor deposition apparatus for preparing doped silicon carbide according to claim 8, characterized in that, The agitator is made of polytetrafluoroethylene and / or perfluoroalkoxy resin.

10. The chemical vapor deposition apparatus for preparing doped silicon carbide according to any one of claims 6-9, characterized in that, The device further includes: The gas distribution structure has an inlet end connected to the bubbler and multiple outlet ends connected to the reaction chamber, which is used to deliver the carrier gas carrying the micro-droplets to the reaction chamber in multiple ways.

Images