Preparation method of transition layer of Sic coating graphite base

Abstract

The invention discloses a preparation method of a SiC coating graphite base transition layer. The technical problems that in the prior art, the bonding force between a SiC coating and a graphite base is insufficient, and the compactness of the coating is poor are solved. The method comprises the following steps: gradient functionalization pretreatment: carrying out plasma microcosmic roughening treatment and organosilicon compound dipping-pyrolysis-nitriding treatment on a graphite base to form a Si-C-O-N functionalized transition layer; multi-stage pulse chemical vapor deposition is carried out, low-temperature seed layer deposition, medium-temperature growth layer deposition and high-temperature densification layer deposition are carried out in three stages, and different pulse periods and precursor combinations are adopted; in-situ plasma auxiliary treatment is conducted, and plasma treatment is conducted at the deposition stage interval and after the final stage is completed. Strong interface combination of the graphite substrate and the SiC coating is achieved through unique gradient functionalization pretreatment, the coating density is improved through the multi-stage pulse CVD technology, the performance of the SiC coating graphite base in semiconductor processing and high-temperature plasma environments is remarkably improved, and the service life of the SiC coating graphite base in the semiconductor processing and high-temperature plasma environments is remarkably prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of graphite base transition layer production, in particular to a method for preparing a SiC-coated graphite base transition layer. Background Art

[0002] Graphite susceptors are widely used in semiconductor manufacturing, high-temperature plasma processing equipment, and photovoltaic production equipment due to their excellent thermal conductivity, low thermal expansion coefficient, and high high-temperature strength. However, graphite materials suffer from significant physical and chemical instability issues in high-temperature and corrosive environments. During the fabrication of semiconductor or optoelectronic devices, graphite susceptors are exposed to harsh environments such as high temperatures, strong plasmas, and corrosive gases. These conditions can easily lead to surface erosion, particle shedding, and gas permeation, contaminating the process environment and shortening the equipment's lifespan. Therefore, protective treatment of the graphite susceptor surface has become a key technology for improving its performance and lifespan.

[0003] Silicon carbide has become an ideal coating material for protecting graphite bases due to its excellent high temperature resistance, corrosion resistance and high hardness. In the existing technology, the methods for preparing SiC coatings mainly include chemical vapor deposition, liquid phase impregnation-pyrolysis and plasma spraying. However, these traditional methods face two major challenges when preparing SiC coatings: first, the bonding force between the SiC coating and the graphite substrate is insufficient, and it is easy to peel and fall off under high temperature and thermal cycling conditions; second, the prepared SiC coating has many micropores and defects inside and poor density, which leads to a decrease in the corrosion resistance of the coating and is unable to effectively prevent the corrosion of the graphite substrate by corrosive gases.

[0004] In response to the problem of insufficient interface bonding between SiC coatings and graphite substrates, researchers have explored a variety of improvement methods. Some researchers have tried to increase the mechanical bite area of ​​the interface through physical roughening treatments, such as sandblasting and chemical etching; other researchers have introduced a transition layer at the interface, such as first coating a Si layer, SiO2 layer or a carbonized transition layer. Other researchers have used chemical vapor infiltration to allow SiC to first penetrate the surface of the graphite substrate and then form a surface coating. Although these methods have improved the interface bonding performance to a certain extent, the effect is limited, especially under long-term high-temperature cycling conditions, interface delamination is still common. The reason is that these methods fail to solve the problems of both chemical bonding and mechanical bonding at the interface at the same time, and fail to form an effective composition gradient transition area.

[0005] The methods for improving the density of SiC coatings in the prior art include high-temperature CVD process, hot isostatic pressing and multi-layer composite deposition. Traditional CVD process usually adopts continuous gas supply mode and carries out long-term deposition at high temperature (usually >1200°C). Although the coating obtained has high purity, the process energy consumption is large, and it is difficult to accurately control the SiC grain size and morphology. Micropores and defects still exist inside the coating. Some researchers have tried to use methods such as pulsed laser deposition or atomic layer deposition to prepare high-density SiC coatings, but these methods have disadvantages such as high cost, low efficiency or limited applicable size, and are difficult to apply on an industrial scale. In addition, the prior art pays less attention to in-situ surface treatment during the deposition process, which makes it difficult to simultaneously optimize the bonding between each layer and the overall density. Therefore, it is of great practical value and technical significance to develop a new method for preparing a transition layer of a SiC coating graphite base that can simultaneously solve the problems of interface bonding and coating density. Summary of the Invention

[0006] Based on the above purpose, the present invention provides a method for preparing a transition layer of a SiC coated graphite base

[0007] The following steps are involved:

[0008] Step 1: Gradient functionalization pretreatment: The surface of the graphite base is subjected to plasma micro-roughening treatment, and then an organic silicon compound impregnation-pyrolysis-nitridation process is used to form a Si-CON functional transition layer;

[0009] Step 2: Multi-stage pulsed chemical vapor deposition: depositing a low-temperature seed layer, a medium-temperature growth layer, and a high-temperature densification layer in three stages to form a SiC coating;

[0010] Step 3: In-situ plasma-assisted treatment: Plasma treatment is performed between each deposition stage and after the final stage.

[0011] Furthermore, the plasma micro-roughening treatment in the gradient functionalization pretreatment uses argon plasma with a power of 200-250W and a treatment time of 5-7 minutes, forming a micro-concave-convex structure 3-8μm deep on the surface of the graphite base; the organic silicon compound impregnation uses a mixed solution of tetraethoxysilane and polycarbosilane for 24 hours; the pyrolysis process is kept at 350-380°C for 2-3 hours, and then kept at 650-700°C for 4-5 hours; the nitriding treatment is carried out at 400-420°C, and high-purity nitrogen is introduced for 2-3 hours.

[0012] Furthermore, the first stage of the multi-stage pulsed chemical vapor deposition is carried out at 900-950° C., using methyltrichlorosilane and hydrogen as precursors, and the pulse gas supply mode is 10 seconds of gas supply and 5 seconds of pause, with a total of 100-120 pulse cycles.

[0013] Furthermore, the second stage of multi-stage pulsed chemical vapor deposition was carried out at 1100-1150°C, using methyltrichlorosilane, hydrogen and methane as precursors, with a molar ratio of methyltrichlorosilane to hydrogen of 1:7-1:8, and a molar ratio of methane to methyltrichlorosilane of 0.5:1. The pulse gas supply mode was 20 seconds of gas supply and 3 seconds of pause, for a total of 120 pulse cycles.

[0014] Furthermore, the third stage of multi-stage pulsed chemical vapor deposition is carried out at 1180-1200°C, using methyltrichlorosilane, hydrogen, methane and hexamethyldisilane as precursors, with a molar ratio of hexamethyldisilane to methyltrichlorosilane of 0.1:1-0.15:1, and the pulse gas supply mode is 30 seconds of gas supply and 2 seconds of pause, for a total of 80 pulse cycles.

[0015] Furthermore, the plasma treatment between each deposition stage uses argon plasma with a power of 40W and a treatment time of 8 seconds; the plasma treatment after the final stage uses a mixed plasma of argon and hydrogen with an argon flow rate of 300ml / min, a hydrogen flow rate of 200ml / min, a power of 45-50W, a treatment time of 12-15 minutes, and a treatment temperature of 800°C.

[0016] Furthermore, each step in the preparation method is performed continuously, and the graphite base is high-purity graphite with a purity of ≥99.99%.

[0017] Preferably, the SiC-coated graphite base transition layer is prepared by the preparation method.

[0018] The above-mentioned SiC-coated graphite base transition layer is used as a base material in semiconductor processing equipment or high-temperature plasma environment equipment.

[0019] Beneficial effects of the present invention:

[0020] 1. The present invention adopts a gradient functionalization pretreatment process, and through the synergistic effect of plasma micro-roughening treatment and organosilicon compound impregnation-pyrolysis-nitridation multi-step, a Si-CON functionalized layer with a gradient transition in composition and structure is established on the surface of the graphite substrate. This innovative pretreatment method simultaneously enhances the mechanical bite and chemical bonding of the interface: the 3-8μm deep concave-convex structure formed by the micro-roughening treatment significantly increases the interface contact area, while the Si-CON functionalized layer forms a chemical composition gradient transition zone between the graphite substrate and the SiC coating, effectively alleviating the interface stress caused by the difference in thermal expansion coefficient. According to tests, the interface bonding strength between the SiC coating prepared by the present invention and the graphite substrate reached more than 35MPa, and there was no obvious peeling phenomenon after 100 cycles between 25°C and 1200°C, which greatly improved the interface stability and service life of the coating.

[0021] 2. The present invention innovatively adopts a multi-stage pulsed chemical vapor deposition process. According to the growth law of SiC crystals, different precursor combinations and pulse gas supply parameters are used at different temperatures to achieve precise control of the layering of the SiC coating from the inside to the outside. In the first stage, the low-temperature seed layer is deposited to form a high-density nucleation site. In the second stage, the medium-temperature growth layer is deposited to promote the vertical growth of SiC grains. In the third stage, the high-temperature densification layer is deposited in combination with the addition of HMDS auxiliary precursor to effectively fill the micropores and defects of the previous deposition layer. In combination with the in-situ plasma-assisted treatment between stages, the bonding state and overall structure between the layers are further optimized. According to tests, the density of the SiC coating prepared by the present invention reaches more than 99.2%, the surface roughness of the coating is Ra≤0.15μm, and there is no obvious corrosion phenomenon after immersion in HF / HNO3 mixed acid for 48 hours. The corrosion resistance is improved by more than 40% compared with the traditional process.

[0022] 3. Compared with the traditional continuous CVD process, the multi-stage pulse CVD process proposed in the present invention effectively reduces the overall energy consumption of the process through staged temperature control and pulse gas supply mode. First, the low-temperature seed layer deposition temperature in the first stage is only 900-950°C, which is significantly lower than the temperature of more than 1300°C usually required by the traditional CVD process; secondly, the pulse gas supply mode greatly reduces the consumption of precursor gas and improves the gas utilization rate; thirdly, the entire coating deposition process can be completed continuously in the same equipment, avoiding the pollution and efficiency loss caused by sample transfer and multi-equipment processing. In addition, by adjusting the process parameters, the present method can flexibly adapt to different application requirements and prepare SiC-coated graphite bases with different thicknesses and different surface roughness, as shown in Example 1 and Example 2. According to statistics, compared with the traditional process, the method of the present invention reduces energy consumption by about 30% and precursor consumption by 25% under the same coating performance indicators, and improves process repeatability and product consistency by more than 35%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the gradient functionalization pretreatment process of the present invention;

[0025] Figure 2 Schematic diagram of the multi-stage pulsed chemical vapor deposition process of the present invention;

[0026] Figure 3 Schematic diagram of the cross-sectional structure of the SiC-coated graphite base of the present invention;

[0027] Figure 4 Schematic diagram of the multi-stage pulsed CVD process equipment of the present invention;

[0028] Figure 5 Schematic diagram of the temperature-time-gas supply relationship of the pulsed CVD process of the present invention. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. It is also noted that, to provide a more detailed description, the following embodiments are best and preferred embodiments, and those skilled in the art may employ alternative methods for implementing certain known technologies. Furthermore, the accompanying drawings are intended only to provide a more detailed description of the embodiments and are not intended to limit the present invention.

[0030] It should be noted that references in the specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," etc. indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment necessarily includes such specific features, structures, or characteristics. In addition, when specific features, structures, or characteristics are described in conjunction with an embodiment, it is within the knowledge of persons skilled in the relevant art to implement such features, structures, or characteristics in conjunction with other embodiments (whether or not explicitly described).

[0031] In general, terms can be understood, at least in part, from their use in context. For example, depending at least in part on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending at least in part on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0032] The present invention discloses a method for preparing a transition layer of a SiC-coated graphite base, comprising three main steps: gradient functionalization pretreatment, multi-stage pulsed chemical vapor deposition, and in-situ plasma-assisted treatment. Each step is described in detail below.

[0033] See Figure 1-Figure 5 shown

[0034] 1. Gradient functionalization pretreatment

[0035] like Figure 1 shown

[0036] 1.1 Graphite substrate preparation S1

[0037] A high-purity (≥99.99%) graphite susceptor with a diameter of 200 mm and a thickness of 15 mm was first polished using 320#, 600#, and 1000# sandpaper to remove the surface oxide layer and contaminants. The susceptor was then cleaned in acetone for 15 minutes using an ultrasonic cleaner, followed by an 15-minute clean in anhydrous ethanol solution, and finally in deionized water for 10 minutes. The susceptor was then dried at 120°C for 2 hours.

[0038] 1.2 Plasma micro-roughening treatment S2

[0039] The prepared graphite substrate was placed in a plasma treatment chamber and evacuated to 5 × 10^-3 Pa. High-purity argon (≥99.999%) was introduced, maintaining a pressure of 20 Pa. The RF power supply was activated to generate plasma at 200 W for 5 minutes. This step formed a microscopic concave-convex structure approximately 5 μm deep on the graphite surface, increasing the mechanical engagement area for subsequent coatings.

[0040] 1.3 Organic silicon compound impregnation treatment S3

[0041] Prepare the impregnation solution: Dissolve 5 g of tetraethoxysilane in 45 g of anhydrous ethanol, add 0.5 g of acetic acid as a catalyst, and stir to form Solution A. Dissolve 2 g of polycarbosilane in 18 g of toluene to form Solution B. Mix Solution A and Solution B in a 1:1 volume ratio and sonicate for 15 minutes to ensure thorough mixing.

[0042] Immerse the plasma-treated graphite susceptor in the mixed solution at room temperature for 24 hours. Remove and allow to air dry at room temperature for 2 hours, then dry at 60°C for 4 hours to ensure complete evaporation of the solvent.

[0043] 1.4 Pyrolysis treatment S4

[0044] The impregnated graphite base was placed in a tubular furnace and introduced with high-purity argon at a flow rate of 500 ml / min. The temperature was raised from room temperature to 350°C at a rate of 5°C / min and kept at that temperature for 2 hours. The temperature was then raised to 650°C at a rate of 3°C / min and kept at that temperature for 4 hours to complete the thermal decomposition process of the organosilicon compound and form a Si-CO functionalized transition layer with a thickness of about 0.8 μm.

[0045] 1.5 Nitriding treatment S5

[0046] After pyrolysis is complete, the temperature is lowered to 400°C and the inlet gas is switched to high-purity nitrogen (≥99.999%) at a flow rate of 800 ml / min. The treatment is maintained for 2 hours. This process introduces Si-N bonds into the functionalized transition layer, further enhancing the interfacial bonding of the subsequent SiC coating. After treatment, the material is allowed to cool naturally to room temperature.

[0047] 2. Multi-stage pulsed chemical vapor deposition process

[0048] See Figure 1 Step S6, and Figure 2

[0049] 2.1 Equipment Preparation

[0050] A vertical hot-wall CVD reactor equipped with a radio frequency plasma generator is used. The reactor chamber is made of quartz, with an inner diameter of 300 mm and a height of 500 mm. A gas distributor is installed at the bottom of the reactor to ensure uniform flow of reactant gases. The top of the reactor is equipped with a gas outlet and a connection for the vacuum system. An induction heater is installed in the middle of the reactor, enabling precise temperature control within ±5°C.

[0051] 2.2 Stage 1: Low-temperature seed layer deposition S61

[0052] A graphite susceptor pretreated with gradient functionalization was placed in the center of the reactor. After evacuation to 1×10^-2 Pa, high-purity argon was introduced into the reaction chamber three times. The temperature was then raised to 900°C at a rate of 5°C / min.

[0053] At 900°C, the seed layer was deposited using pulsed gas supply S62:

[0054] Methyltrichlorosilane was introduced into the reaction chamber by hydrogen as a carrier gas (H2 flow rate was 500 ml / min), and the molar ratio of MTS to H2 was controlled to be 1:10.

[0055] The pulse gas supply mode is adopted: gas supply is 10 seconds, and pause is 5 seconds, which constitutes a complete pulse cycle.

[0056] A total of 100 pulse cycles were performed, which was approximately 25 minutes.

[0057] During this stage, a SiC seed layer with a thickness of about 0.5 μm is formed, which is mainly composed of fine SiC grains and provides nucleation sites for subsequent growth.

[0058] 2.3 Second stage: medium temperature growth layer deposition S63-S64

[0059] After the first stage is completed, the temperature is raised to 1100°C at a rate of 8°C / min. At this temperature, the reaction gas composition is adjusted as follows:

[0060] The molar ratio of MTS to H2 was adjusted to 1:8.

[0061] Methane was added so that the molar ratio of CH4 to MTS was 0.5:1.

[0062] The total gas flow rate was maintained at 800 ml / min.

[0063] Adjust the pulse gas supply mode to: supply gas for 20 seconds and pause for 3 seconds.

[0064] 120 pulse cycles are performed, which is approximately 46 minutes.

[0065] In this stage, a SiC growth layer with a thickness of about 2.5 μm is formed. The grain size is larger than that in the first stage, forming a columnar structure.

[0066] 2.4 The third stage: high temperature densification layer deposition S65

[0067] After completing the second stage, the temperature was raised to 1180°C and kept stable. Adjust the reaction gas composition:

[0068] The molar ratio of MTS to H2 was maintained at 1:8.

[0069] Methane flow remains unchanged.

[0070] Hexamethyldisilane was added so that the molar ratio of HMDS to MTS was 0.1:1.

[0071] The total gas flow rate was controlled at 850 ml / min.

[0072] Adjust the pulse gas supply mode to: supply gas for 30 seconds and pause for 2 seconds.

[0073] 80 pulse cycles are performed, which is approximately 43 minutes.

[0074] In this stage, a densified SiC layer with a thickness of about 2 μm is formed to fill the micropores and defects that may exist in the previous two stages.

[0075] 3. In-situ plasma-assisted treatment

[0076] See Figure 2 S65 steps

[0077] 3.1 Interstage plasma treatment

[0078] After each deposition stage and before the next stage begins, a plasma-assisted treatment is performed:

[0079] All precursor gas supplies were suspended, and only high-purity argon gas was introduced at a flow rate of 300 ml / min.

[0080] The radio frequency power supply was started and the power was set to 40 W to generate low-power argon plasma.

[0081] The processing time is 8 seconds.

[0082] After the plasma treatment, the RF power supply was turned off and the next stage of deposition was started after waiting for 30 seconds.

[0083] 3.2 Final surface integration treatment

[0084] After all deposition stages are completed, the final surface integration process is performed:

[0085] Lower the temperature to 800°C.

[0086] A mixed gas of argon and hydrogen was introduced, with an argon flow rate of 300 ml / min and a hydrogen flow rate of 200 ml / min.

[0087] The radio frequency power supply was started at a power of 45 W to generate mixed plasma.

[0088] The processing time is 12 minutes.

[0089] After the treatment, the RF power supply was turned off, the hydrogen supply was cut off, and the sample was cooled naturally to room temperature under an argon atmosphere.

[0090] Example 1: Preparation of SiC-coated graphite susceptor for semiconductor processing

[0091] Materials and Equipment

[0092] High-purity graphite susceptor: 200mm diameter, 15mm thickness, 99.99% purity; plasma treatment equipment: power range: 0-500W, frequency: 13.56MHz; tube furnace: maximum temperature: 1400°C, adjustable heating rate; CVD reactor: quartz chamber, vertical hot wall type, temperature control accuracy: ±5°C; chemical reagents: tetraethoxysilane, polycarbosilane, methyltrichlorosilane, hexamethyldisilane.

[0093] Specific steps

[0094] Graphite substrate pretreatment

[0095] Use 320#, 600#, and 1000# sandpaper to polish the surface of the graphite base in sequence; ultrasonic cleaning: acetone for 15 minutes → anhydrous ethanol for 15 minutes → deionized water for 10 minutes; dry in a drying oven at 120°C for 2 hours.

[0096] Plasma roughening treatment

[0097] The graphite base was placed in a plasma chamber and evacuated to 5×10^-3Pa; argon gas was introduced to a pressure of 20Pa, and the radio frequency power supply was started with a power setting of 200W; the processing time was 5 minutes, and a microscopic concave-convex structure with a depth of about 5μm was formed on the surface.

[0098] Organic silicon compound impregnation treatment

[0099] Prepare solution A: 5g TEOS + 45g anhydrous ethanol + 0.5g acetic acid; prepare solution B: 2g PCS + 18g toluene; mix solutions A and B in a 1:1 volume ratio and sonicate for 15 minutes; immerse the graphite base in the mixed solution for 24 hours; dry at room temperature for 2 hours and then at 60°C for 4 hours.

[0100] Pyrolysis treatment

[0101] The graphite base was placed in a tube furnace and argon gas (500 ml / min) was introduced; the temperature was increased to 350°C at 5°C / min and kept at this temperature for 2 hours; the temperature was increased to 650°C at 3°C / min and kept at this temperature for 4 hours; and a Si-CO functionalized transition layer with a thickness of about 0.8 μm was formed.

[0102] Nitriding treatment

[0103] The temperature was lowered to 400° C. and switched to nitrogen (800 ml / min); the treatment was maintained for 2 hours to introduce Si—N bonds; and the mixture was naturally cooled to room temperature.

[0104] Stage 1: Low-temperature seed layer deposition

[0105] The graphite base was placed in a CVD reactor and evacuated to 1×10^-2Pa; the temperature was raised to 900°C, and MTS and H2 (molar ratio 1:10) were introduced; pulse gas supply mode: gas supply for 10 seconds, pause for 5 seconds; a total of 100 pulse cycles (about 25 minutes) were performed to form a SiC seed layer with a thickness of about 0.5μm.

[0106] Plasma treatment after the first stage: suspend the precursor gas and introduce argon (300 ml / min); RF power 40 W, treatment time 8 seconds; turn off the RF power and wait for 30 seconds.

[0107] Stage 2: Deposition of the Intermediate-Temperature Growth Layer

[0108] The temperature was raised to 1100°C; MTS, H2 and CH4 (molar ratio 1:8:0.5) were introduced; pulse gas supply mode: gas supply for 20 seconds, pause for 3 seconds; a total of 120 pulse cycles (about 46 minutes); a SiC growth layer with a thickness of about 2.5 μm was formed.

[0109] Second stage post-plasma treatment: suspend the precursor gas and introduce argon (300 ml / min); RF power 40 W, treatment time 8 seconds; turn off the RF power and wait for 30 seconds.

[0110] Stage 3: High-temperature densification layer deposition

[0111] The temperature was raised to 1180°C; MTS, H2, CH4 and HMDS (MTS 24 =1:8:0.5:0.1); pulse gas supply mode: gas supply for 30 seconds, pause for 2 seconds; a total of 80 pulse cycles (about 43 minutes); a densified SiC layer with a thickness of about 2 μm was formed.

[0112] Final surface integration treatment: temperature dropped to 800°C; argon (300 ml / min) and hydrogen (200 ml / min) were introduced; RF power was 45 W, and treatment time was 12 minutes; RF power was turned off, and the argon atmosphere was maintained and cooled to room temperature.

[0113] Example Results Evaluation

[0114] The SiC-coated graphite susceptor prepared according to the above steps has the following properties after testing:

[0115] Total coating thickness: 5.0±0.3μm; interface bonding strength between coating and substrate: ≥35MPa; surface roughness Ra of coating: 0.15μm; density of coating: ≥99.2%, corrosion resistance: no obvious corrosion phenomenon after immersion in HF / HNO3 mixed acid (volume ratio 1:3) for 24 hours.

[0116] Thermal cycling stability: The coating shows no cracking or peeling after 100 cycles between 25°C and 1000°C.

[0117] Example 2: Preparation of SiC-coated graphite susceptor for high-temperature plasma environment

[0118] The main difference between this embodiment and embodiment 1 lies in the adjustment of plasma roughening treatment parameters, organic silicon compound formulation ratio, and CVD deposition process parameters to adapt to a more severe high-temperature plasma working environment.

[0119] Specific steps to adjust

[0120] Plasma roughening treatment: The power was increased to 250W; the treatment time was extended to 7 minutes; a microscopic concave-convex structure with a depth of about 7.5 μm was formed on the surface.

[0121] Organic silicon compound impregnation treatment: prepare solution A: 6 g TEOS + 44 g anhydrous ethanol + 0.6 g acetic acid; prepare solution B: 3 g PCS + 17 g toluene; mix solutions A and B in a volume ratio of 1.2:1.

[0122] Pyrolysis treatment: heating to 380°C at 4°C / min and holding for 3 hours; heating to 700°C at 2.5°C / min and holding for 5 hours; forming a Si-CO functionalized transition layer with a thickness of about 1.0 μm.

[0123] Nitriding treatment: the temperature was lowered to 420°C, the nitrogen flow rate was increased to 900 ml / min, and the treatment time was extended to 3 hours.

[0124] CVD deposition process parameter adjustments: Stage 1: Temperature increased to 950°C, pulse cycle increased to 120. Stage 2: Temperature increased to 1150°C, MTS:H2 molar ratio adjusted to 1:7. Stage 3: Temperature increased to 1200°C, HMDS:MTS molar ratio increased to 0.15:1. The pulse count was increased by 20% in each stage, resulting in a total SiC coating thickness of approximately 6.5μm.

[0125] Final surface integration treatment: treatment time extended to 15 minutes; RF power increased to 50W.

[0126] Example Results Evaluation

[0127] The SiC-coated graphite susceptor prepared according to the adjusted procedures demonstrated the following properties: total coating thickness: 6.5 ± 0.4 μm; coating-substrate interface strength: ≥ 42 MPa; coating surface roughness Ra: 0.12 μm; coating density: ≥ 99.5%. Corrosion resistance: No significant corrosion was observed after immersion in a 1:3 volume ratio of HF / HNO3 mixed acid for 48 hours.

[0128] Thermal cycling stability: The coating shows no cracking or peeling after 100 cycles between 25°C and 1200°C.

[0129] Plasma corrosion resistance: After continuous exposure to SF6 / O2 mixed gas plasma at 500W for 200 hours, the coating thickness does not decrease by more than 0.5μm.

[0130] The above two embodiments demonstrate in detail the specific preparation method of the SiC-coated graphite base transition layer of the present invention. By adjusting the process parameters, it can adapt to the needs of different application scenarios and significantly improve the performance and service life of the graphite base in semiconductor processing and high-temperature plasma environments.

[0131] The present invention encompasses any alternatives, modifications, equivalents, and solutions that fall within the spirit and scope of the present invention. To provide a thorough understanding of the present invention, specific details are described in detail below in connection with the preferred embodiments of the present invention, but those skilled in the art will be able to fully understand the present invention without these detailed descriptions. Furthermore, to avoid unnecessary confusion regarding the essence of the present invention, well-known methods, processes, procedures, components, and circuits have not been described in detail.

[0132] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a transition layer of a SiC-coated graphite base, characterized in that: The following steps are involved: Step 1: Gradient functionalization pretreatment: The surface of the graphite base is subjected to plasma micro-roughening treatment, and then an organic silicon compound impregnation-pyrolysis-nitridation process is used to form a Si-CON functional transition layer; Step 2: Multi-stage pulsed chemical vapor deposition: depositing a low-temperature seed layer, a medium-temperature growth layer, and a high-temperature densification layer in three stages to form a SiC coating; Step 3: In-situ plasma-assisted treatment: Plasma treatment is performed between each deposition stage and after the final stage.

2. The preparation method according to claim 1, characterized in that The plasma micro-roughening treatment in the gradient functionalization pretreatment uses argon plasma with a power of 200-250W and a treatment time of 5-7 minutes, forming a micro-concave-convex structure 3-8 μm deep on the surface of the graphite base; the organic silicon compound impregnation uses a mixed solution of tetraethoxysilane and polycarbosilane for 24 hours; the pyrolysis process is kept at 350-380°C for 2-3 hours, and then kept at 650-700°C for 4-5 hours; the nitriding treatment is carried out at 400-420°C, with high-purity nitrogen introduced, and the treatment time is 2-3 hours.

3. The preparation method according to claim 1, characterized in that The first stage of the multi-stage pulsed chemical vapor deposition is carried out at 900-950° C., using methyltrichlorosilane and hydrogen as precursors, and the pulse gas supply mode is 10 seconds of gas supply and 5 seconds of pause, with a total of 100-120 pulse cycles.

4. The preparation method according to claim 1, characterized in that The second stage of the multi-stage pulsed chemical vapor deposition is carried out at 1100-1150° C., using methyltrichlorosilane, hydrogen and methane as precursors, with a molar ratio of methyltrichlorosilane to hydrogen of 1:7-1:8, and a molar ratio of methane to methyltrichlorosilane of 0.5:

1. The pulse gas supply mode is 20 seconds of gas supply and 3 seconds of pause, for a total of 120 pulse cycles.

5. The preparation method according to claim 1, characterized in that The third stage of the multi-stage pulsed chemical vapor deposition is carried out at 1180-1200° C., using methyltrichlorosilane, hydrogen, methane and hexamethyldisilane as precursors, with a molar ratio of hexamethyldisilane to methyltrichlorosilane of 0.1:1-0.15:

1. The pulse gas supply mode is 30 seconds of gas supply and 2 seconds of pause, with a total of 80 pulse cycles.

6. The preparation method according to claim 1, characterized in that The plasma treatment between each deposition stage adopts argon plasma with a power of 40W and a treatment time of 8 seconds; the plasma treatment after the final stage adopts a mixed plasma of argon and hydrogen with an argon flow rate of 300ml / min, a hydrogen flow rate of 200ml / min, a power of 45-50W, a treatment time of 12-15 minutes, and a treatment temperature of 800°C.

7. The preparation method according to any one of claims 1 to 6, characterized in that The various steps in the preparation method are performed continuously, and the graphite base is made of high-purity graphite with a purity of ≥99.99%.

8. A SiC-coated graphite base transition layer prepared by the preparation method according to any one of claims 1 to 7.

9. The SiC-coated graphite base transition layer according to claim 8, characterized in that: Used as a base material in semiconductor processing equipment or high-temperature plasma environment equipment.

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