Plasma-assisted silicon carbide heating element deposition method

Abstract

The invention discloses a plasma-assisted silicon carbide heating element deposition method, and particularly relates to the technical field of silicon carbide heating element preparation. Methane and silane gas are introduced into a plasma reaction cavity, plasma is applied, a pre-activated gas mixture is formed, and a high-surface-energy initial nucleophilic layer is formed on the surface of a substrate; then introducing argon, hydrogen and a silicon carbide film; plasma irradiation dose distribution D (x, y) is obtained through two-dimensional area array spectral measurement, and stress distribution sigma (x, y) is reconstructed in combination with a finite element model; modulating plasma power P (x, y) to realize local stress compensation according to the transverse normalized stress increment and the longitudinal irradiation dose gradient; and finally, low-temperature annealing is performed to enhance the film stability and the interface bonding force. The method has the advantages of low stress, high uniformity, high reliability and the like, and is suitable for preparing high-performance heating elements.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide heating element fabrication technology, specifically to a plasma-assisted silicon carbide heating element deposition method. Background Technology

[0002] With the development of high-precision heat treatment technology, miniature heating elements that can operate stably in extreme environments (such as vacuum, highly corrosive atmospheres, and high-frequency electromagnetic interference) have become key components in high-end equipment manufacturing, and are widely used in fields such as aero-engine ignition systems, plasma etching equipment, and MEMS thermal sensing systems. Among them, heating elements made of silicon carbide (SiC) have become a research hotspot due to their excellent high-temperature stability, corrosion resistance, and wide bandgap characteristics.

[0003] However, existing methods for preparing SiC thin film heating elements generally employ chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques. When depositing in micro-nano scale structures, the following problems are difficult to overcome: (1) The film thickness is extremely uneven in non-flat substrates (such as 3D grooves and stepped structures), resulting in uneven heating; (2) Stress gradients are easily formed under traditional heating methods, causing the deposited film to peel off or crack during high-temperature operation; (3) The high-temperature processing temperature exceeds 1200℃, which limits the compatibility of various functional substrates.

[0004] In particular, when manufacturing a flexible ceramic heating film that is only a few hundred micrometers thick, traditional methods cannot achieve both high density and low stress, resulting in insufficient device lifespan and frequent failures, which has become a key bottleneck restricting the reliability improvement of the next generation of high-precision thermal control systems.

[0005] Therefore, there is an urgent need to propose a novel plasma-assisted silicon carbide heating element deposition method that can significantly reduce internal stress while maintaining film uniformity, thereby achieving high-reliability deposition on complex substrates and improving device thermal stability and lifespan. Summary of the Invention

[0006] The purpose of this invention is to provide a plasma-assisted silicon carbide heating element deposition method to address the shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a plasma-assisted silicon carbide heating element deposition method, comprising: S100: Provides a ceramic substrate with a micro-nano composite groove structure and places it in a reaction chamber, wherein the surface roughness Ra of the ceramic substrate is <100 nm; S200: Carbon source gas and silicon source gas are introduced into the reaction chamber, and radio frequency plasma with a frequency of 13.56 MHz is applied to form a pre-activated gas mixture to generate an initial nucleophilic layer on the surface of the ceramic substrate, wherein the surface energy of the nucleophilic layer is not less than 50 mN / m. S300: After forming the nucleophilic layer, adjust the temperature of the reaction zone to no higher than 850°C, and introduce the auxiliary gas Ar. Maintaining the plasma state, silicon carbide thin film deposition is performed until the deposition thickness reaches a set value T1, where T1 is less than 2 μm; S400: Obtain the plasma irradiation dose distribution D(x,y) on the surface of the deposited thin film, where D(x,y) is a two-dimensional spatial function used to characterize the local deposition stress distribution; S500: Based on the region with the largest stress gradient change in D(x,y), implement local power modulation and dynamically adjust the plasma excitation power P(x,y) to achieve stress compensation in the target region, so that the overall stress gradient Δσ is less than 10MPa. S600: After stress compensation is completed, low-temperature annealing is performed, with the temperature controlled at 600–700℃, to further stabilize the film structure and enhance its interfacial bonding strength.

[0008] Preferably, the micro-nano composite trench structure in step S100 includes: forming a micrometer-scale trench array with a period of 20 μm and a depth of 2.5 μm by photolithography and reactive ion etching; and forming a density of approximately [missing information - likely a number] on the bottom and sidewalls of the trenches by etching with a nanosphere mask and oxygen plasma. A nanoscale array of pits per cm² with a depth of 200–300 nm.

[0009] Preferably, the ceramic substrate in step S100 is a high-purity dense sintered alumina ceramic sheet with a purity of not less than 99.6% and a surface roughness Ra of 46.2 nm. It is subjected to chemical mechanical polishing and plasma activation treatment. The activation treatment uses pure oxygen gas with a radio frequency power of 100 W, a frequency of 13.56 MHz, and a treatment time of 60 seconds.

[0010] Preferably, the pre-activated gas mixture in step S200 is composed of methane gas and silane gas, with gas flow rates of 30 sccm and 10 sccm respectively, the plasma excitation time is 120 seconds, the plasma is a 13.56 MHz radio frequency plasma, the initial power is 80 W, and the excitation mode is continuous wave mode.

[0011] Preferably, the auxiliary gas in step S300 is argon and hydrogen, with flow rates of 80 sccm and 50 sccm, respectively, the deposition rate of the silicon carbide thin film is 12 nm / min, and the final deposition thickness T1 is controlled between 800 nm and 1.5 μm.

[0012] Preferably, in step S300, the substrate tray is cleaned every 20 minutes during the deposition process. Rotational reversal operation.

[0013] Preferably, in step S400, D(x,y) is obtained by setting a planar array spectral acquisition device at the top of the reaction chamber, and using an energy irradiation conversion model based on the normalized integral intensity of the plasma luminescence intensity in the two bands of 431 nm and 389 nm. The calculations show that k is 0.85, t is 180 seconds, D(x,y) represents the energy irradiation dose per unit area, and I(x,y) is the unit normalized luminous intensity collected by the area array CCD.

[0014] Preferably, the plasma excitation power P(x,y) in step S500 is calculated as follows: First, identify regions where the stress gradient Δσ(x,y) exceeds 50 MPa; then calculate the transverse normalized stress increment in these regions. With longitudinal irradiation dose gradient coefficient Final power modulation coefficient and will , It is 80 W.

[0015] Preferably, the spatial partitioning RF power modulation in step S500 is achieved by controlling the output power of each sub-region in the RF power supply array, with the output power ranging from 20 to 120 watts, and the modulation target is to reduce the overall stress gradient Δσ of the thin film to below 10 MPa.

[0016] Preferably, the low-temperature annealing treatment in step S600 is carried out at 650°C for 90 minutes, the atmosphere used is high-purity argon gas with a purity of not less than 99.999% and a flow rate of 200 sccm, and it is naturally cooled to room temperature in an inert atmosphere.

[0017] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. This invention effectively improves the nucleation density and bonding strength at the deposition interface and significantly reduces the initial stress gradient by constructing a micro-nano composite groove structure, introducing a plasma-assisted pre-activated nucleophilic layer, and depositing silicon carbide thin films at low temperatures. This solves the problems of poor film adhesion, poor deposition uniformity, and easy cracking failure that exist in traditional methods when depositing silicon carbide thin films on complex ceramic substrates. Through the inducing effect of the high surface energy nucleophilic layer, dense and continuous SiC film growth is ensured at lower temperatures, broadening the application range of heating elements on various temperature-sensitive materials.

[0018] 2. This invention proposes for the first time a dynamic power modulation compensation method based on the linkage of a two-dimensional plasma irradiation dose distribution function D(x,y) and a stress distribution function σ(x,y). Combined with a custom-defined transverse normalized stress increment and a longitudinal dose gradient coefficient, it achieves directional compensation control for localized stress concentration regions, significantly reducing the final stress gradient Δσ to below 10 MPa. This will be further supported by subsequent... The low-temperature annealing process further stabilizes the film structure and interface bonding state, significantly improving the service life and reliability of silicon carbide heating elements under harsh conditions such as high-temperature cycling and electrothermal shock, and has broad engineering application prospects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0020] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] For examples, please refer to Figure 1 As shown, the plasma-assisted silicon carbide heating element deposition method described in this embodiment includes: S100: Provide a ceramic substrate with a micro-nano composite groove structure and place it in a reaction chamber, wherein the surface roughness Ra of the ceramic substrate is <100 nm.

[0023] In a preferred embodiment of the present invention, the substrate material used for depositing silicon carbide thin films is a high-purity, dense sintered alumina ceramic sheet. Its purity is 99.6%, and its coefficient of thermal expansion is... It has good thermal stability and electrical insulation, making it suitable for use as a base material for heating elements in plasma environments.

[0024] The ceramic sheet measures 10 mm × 10 mm × 0.5 mm and is obtained through precision cutting. After cutting, the ceramic sheet undergoes the following processing: Double-sided mechanical polishing: Mechanical polishing is performed on a polishing machine using diamond abrasive slurry (particle size 3μm→1μm) to remove the surface mechanical damage layer; Chemical mechanical polishing (CMP): Using nano-cerium oxide slurry, polishing for 15 minutes on a CMP device equipped with a polyurethane pad further reduces surface roughness. AFM measurement: A 5μm × 5μm region was scanned using a Bruker Dimension Icon atomic force microscope, and Ra = 46.2 nm was measured, which meets the requirement of Ra < 100 nm.

[0025] To improve the interfacial bonding strength of subsequent thin film deposition and alleviate thermal stress concentration, a micro / nano composite groove structure is fabricated on the surface of a ceramic substrate, comprising the following two stages: Fabrication of micrometer-scale trench arrays: Photoresist spin coating: Spin coat AZ6130 positive photoresist onto the substrate at 3000 rpm, coating thickness approximately 1.5 μm, pre-baking at 90℃ for 90 seconds; Mask exposure: The substrate is exposed using a UV lithography machine, and the trench array pattern consists of parallel lines with a period of 20μm and a width of 10μm. Development: Develop in AZ MIF 726 developer for 60 seconds to develop the groove pattern; Reactive ion etching (RIE): Etching is performed in an oxygen fluorination process under a specific atmosphere. Power 250W, etching time 3 minutes, trench depth approximately 2.5μm; Stripping: Use acetone to remove the photoresist.

[0026] Fabrication of nanoscale pit structures: Nanosphere mask construction: 1 wt% polystyrene (PS) nanosphere aqueous dispersion (particle size 200 nm) was dropped into the microgroove region and self-assembled into a hexagonal close-packed array by solvent evaporation; Plasma etching: introducing plasma into the RIE system Gas, power 150 W, etching time 30 seconds, using nanospheres as a mask to form a nano-pit array (density ~ (number per cm², depth approximately 250 nm); Nanosphere removal: Wash twice with tetrahydrofuran (THF) to completely remove residual PS particles.

[0027] After completing the above steps, a nanoscale pit array is formed on the bottom and sidewalls of the micron-scale trench, thus forming a micro-nano composite groove structure. This structure can improve interface affinity, improve film uniformity, and mitigate the thermal stress concentration effect.

[0028] Surface cleaning and pretreatment: Ultrasonic cleaning steps (10 minutes each): Acetone → Anhydrous ethanol → Deionized water; Drying: using high-purity... Airflow to dry; Surface activation treatment: Pure O2 gas is introduced into a plasma surface cleaning device with a radio frequency power of 100 W, a frequency of 13.56 MHz, and a treatment time of 60 seconds; this process can introduce active groups such as hydroxyl groups on the ceramic surface, thereby improving the formation efficiency of the initial nucleophilic layer.

[0029] Cavity transfer and pretreatment: Transfer method: Transfer to the PECVD reaction system in a Class 100 clean environment through a sealed quartz box. The transfer process is controlled within 10 minutes to prevent surface adsorption of organic contaminants. Reaction chamber structure: A vertical PECVD device with parallel flat plate electrodes is used. The reaction chamber has a diameter of 150 mm and a height of 100 mm. The substrate is fixed on the temperature control electrode. The base heating platform supports precise control from room temperature to 1000°C. Base pressure maintained at Below Torr, the working pressure is 300 mTorr; The system is equipped with an independent MFC-controlled gas channel, which can simultaneously introduce gas. Multiple gas streams.

[0030] Thus, the preparation and pretreatment of a ceramic substrate with a micro-nano composite groove structure and a surface roughness of less than 100 nm were completed, and it was placed in a plasma reaction chamber to provide a basis for the subsequent plasma-assisted deposition of silicon carbide thin film (S200).

[0031] S200: Carbon source gas and silicon source gas are introduced into the reaction chamber, and radio frequency plasma with a frequency of 13.56 MHz is applied to form a pre-activated gas mixture to generate an initial nucleophilic layer on the surface of the ceramic substrate, wherein the surface energy of the nucleophilic layer is not less than 50 mN / m.

[0032] After completing the preparation, cleaning and placement of the ceramic substrate into the reaction chamber in step S100, a plasma-assisted pre-activation deposition step is performed to form a stable and continuous initial nucleophilic layer on the surface of the ceramic substrate.

[0033] In this embodiment, the reaction chamber is a plasma-enhanced chemical vapor deposition (PECVD) chamber. A ceramic substrate is fixed to a lower electrode substrate tray, which is made of molybdenum alloy and connected to an independent temperature control module.

[0034] Before introducing the reactive gases, perform the following pretreatment steps: Vacuumed to base pressure ≤ Torr; The substrate temperature is raised to 350°C by the heating module and maintained for 10 minutes to remove residual moisture and weakly adsorbed molecules from the substrate surface; after maintaining the chamber pressure stable, the gas introduction stage begins.

[0035] In this embodiment, methane is selected as the carbon source gas. Silane is selected as the silicon source gas. Both are high-purity electronic-grade gases (purity ≥ 99.999%). Specific gas parameters are as follows: Flow rate: 30 sccm; Flow rate: 10 sccm; working pressure of the reaction chamber: 200–300 mTorr; carbon source gas and silicon source gas are introduced into the reaction zone through an independent mass flow controller (MFC), and a uniform mixed gas flow is formed before entering the plasma excitation zone, but no obvious chemical reaction has occurred yet.

[0036] After the gas flow stabilizes, radio frequency plasma is applied to the reaction chamber with the following parameters: radio frequency: 13.56 MHz; initial radio frequency power: 80 W; plasma mode: continuous wave (CW) mode; plasma excitation time: 120 s; under the action of the radio frequency electric field, and Molecules undergo ionization, fragmentation, and excitation, generating a large number of highly reactive neutral free radicals and ionic species, including but not limited to: (x=1–3) carbon free radicals; Silicon-based active species; charged electron clouds and metastable excited molecules. These active species migrate directionally to the surface of a ceramic substrate under the acceleration of the plasma sheath.

[0037] When activated carbon-based and silicon-based species reach the surface of the ceramic substrate, they first undergo selective adsorption in the micro-nano composite groove structure formed in step S100, preferentially occupying the edge regions of the nano-pits and micro-grooves.

[0038] In this embodiment, the formation process of the initial nucleophilic layer includes the following stages: Physical adsorption stage: Active groups undergo transient adsorption in micro / nano structure regions with high surface energy; Chemical bonding stage: Si–O and Si–OH bonds are partially replaced to form Si–C and C–C bonded structures; Continuous transition stage: Discrete nucleophilic sites gradually expand and connect with each other to form a continuous nucleophilic layer covering the entire substrate surface.

[0039] The thickness of the initial nucleophilic layer is controlled in the range of 1–3 nm. It has an amorphous or weakly crystalline structure and does not have a complete silicon carbide lattice, but it provides a stable chemical anchoring layer for the subsequent epitaxial or quasi-epitaxy growth of silicon carbide thin films.

[0040] After completing the plasma pre-activation treatment, the radio frequency power is stopped, the substrate temperature is kept constant, and the reaction chamber is filled with high-purity nitrogen gas for slow back pressure.

[0041] The sample was then removed, and the surface energy of the nucleophilic layer was evaluated using a contact angle meter. Test liquids: deionized water and diiodomethane; Test method: Owens–Wendt method; Measured surface energy range: 52–68 mN / m; The results show that the surface energy of the initial nucleophilic layer formed after plasma-assisted pre-activation is no less than 50 mN / m, which is significantly higher than that of the untreated ceramic substrate (usually <35 mN / m), and can effectively improve the nucleation density and film uniformity in the subsequent silicon carbide deposition stage.

[0042] In step S200, a high surface energy, continuous and stable initial nucleophilic layer is formed on the surface of the ceramic substrate. This nucleophilic layer significantly reduces the nucleation barrier of the subsequent silicon carbide film; it provides a chemical bonding basis for silicon carbide deposition under low temperature conditions in step S300; and it works synergistically with the micro-nano composite groove structure in step S100 to suppress early stress concentration and local delamination of the film.

[0043] S300: After forming the nucleophilic layer, adjust the temperature of the reaction zone to no higher than 850°C, and introduce the auxiliary gas Ar. Maintaining the plasma state, silicon carbide thin film deposition is performed until the deposition thickness reaches a set value T1, where T1 is less than 2 μm.

[0044] After completing the nucleophilic layer construction described in step S200, the main deposition stage of the silicon carbide (SiC) thin film begins. This step aims to uniformly deposit a silicon carbide thin film with controllable thickness, adjustable stress, and dense structure on the surface of the nucleophilic layer using a low-temperature plasma-enhanced chemical vapor deposition (PECVD) method, which is used to construct the core heating layer of a micro high-temperature heating element.

[0045] To ensure thin film growth quality and substrate thermal compatibility, temperature control of the reaction zone is prioritized. Temperature control range: The substrate temperature is slowly increased from 350℃ (nucleophilic layer processing temperature) to 800℃; Heating rate: 10℃ / min, using PID closed-loop temperature control algorithm to ensure temperature fluctuation < ±2℃; Stabilization time: After the temperature reaches the set value, maintain a stable temperature for 5 minutes to ensure uniform temperature across the entire ceramic sheet.

[0046] This temperature setting does not exceed 850℃, taking into account both the minimum crystallization temperature requirement for silicon carbide deposition and the thermal expansion constraint of the ceramic substrate, to prevent the micro-nano structure from becoming unstable due to thermal mismatch.

[0047] In maintaining and Based on the original ratio (3:1), inert gas argon (Ar) and reducing gas hydrogen are introduced. To construct a synergistic atmosphere to improve film density and stress state:

[0048] Gas type effect Flow rate (sccm) <![CDATA[SiH4]]> silicon source 10 <![CDATA[CH4]]> carbon source 30 Ar Dilution and Ion Bombardment Modulation 80 <![CDATA[H2]]> Surface reduction and grain control 50

[0049] System pressure: Adjust to 400 mTorr; The purity of the reactant gases is all 5N grade (99.999%). Flow control method: MKS brand quality flow controller (MFC) is used, with an accuracy error of less than ±1%.

[0050] A stable radio frequency plasma field is maintained during the deposition process to achieve a continuous supply of highly active free radicals and promote surface reactions. Radio frequency: 13.56 MHz; Power setting: Gradually increase from 80 W to 120 W to avoid initial bombardment damage to the nucleophile layer; Discharge mode: Continuous wave (CW); Plasma sheath control: The sheath thickness is adjusted by controlling the electrode spacing and gas ionization to suppress the charge accumulation effect in the film layer.

[0051] In this plasma environment, active species (such as...) The silicon carbide (SiC) is evenly distributed in the reaction zone and undergoes deposition and bonding reactions under the induction of the high surface energy nucleophilic layer, gradually forming an amorphous or microcrystalline silicon carbide film.

[0052] Deposition rate: approximately 12 nm / min; Deposition time: Controlled according to the set target thickness T1, usually 60–150 minutes; The final film thickness T1 is controlled between 800 nm and 1.5 μm, satisfying the requirement that T1 < 2 μm.

[0053] To ensure film uniformity, the substrate tray is rotated (±90°) every 20 minutes during deposition to eliminate film thickness deviations caused by non-uniform spatial distribution of the plasma sheath.

[0054] After deposition, the sample was slowly cooled to room temperature and removed in an inert gas atmosphere. The deposited film was characterized as follows:

[0055] index method Results (Example) Film thickness SEM profile scanning 1.2μm Ingredient ratio XPS Analysis Si:C≈1:1.02 Stress state Raman spectroscopy stress-displacement analysis Stress deviation < ±30 MPa density Transmission electron microscopy (TEM) No obvious columnar defects, dense and uniform Surface roughness Atomic force microscope (AFM) Ra=6.3 nm

[0056] In particular, due to the high density of nucleophilic sites provided by the nucleophilic layer, the film rapidly transitions to a stable growth mode in the initial stage, with regular surface morphology and sharp boundaries, and no obvious delamination or cracks were observed between the film and the substrate.

[0057] In this embodiment, the nucleophilic layer feature "surface energy ≥ 50 mN / m" in step S300 and step S200 form a closed loop effect, ensuring the uniformity of nucleation at the deposition interface; it also provides a uniform initial film structure and quantifiable thickness parameter T1 for stress distribution modeling and adjustment in the subsequent S400; the formed SiC film not only meets the requirements of electrothermal conversion, but also has mechanical stability and interface compatibility, providing a basic material layer for subsequent device construction.

[0058] S400: Obtain the plasma irradiation dose distribution D(x,y) on the surface of the deposited thin film, where D(x,y) is a two-dimensional spatial function used to characterize the local deposition stress distribution.

[0059] After completing the silicon carbide thin film deposition in step S300, in order to identify the local stress gradient changes within the deposition area and obtain the plasma irradiation dose distribution function D(x,y) on the thin film surface, this invention employs a spectral response inversion method under low-power detection mode to convert two-dimensional spatial luminescence intensity information into plasma energy irradiation distribution data, and combines this with a stress reconstruction model to obtain the spatial stress field, providing basic data for subsequent stress compensation. The following are the implementation details of this step: After silicon carbide deposition is completed, the vacuum operation is not activated. The internal pressure of the reaction chamber is maintained at 400 mTorr, and the temperature is maintained at the set value of 800°C when the deposition is completed, to prevent thermal cracking caused by stress release.

[0060] Subsequently, the power of the RF excitation power supply originally used for deposition was reduced from 120 W to 30 W, while the frequency was maintained at 13.56 MHz, and the probe excitation mode was entered. At this time, the plasma energy was significantly lower than the threshold required for deposition, and no new deposition reaction was triggered. Only the residual reactive gas in the cavity and the gas molecules near the thin film surface were excited, achieving stable radiative emission.

[0061] This excitation state can be maintained for 3 minutes to ensure sufficient data sampling time while avoiding temperature rise interference.

[0062] A UV-transmitting quartz window is installed at the top of the reaction chamber, through which the plasma luminescence inside the chamber can be acquired in real time. An imaging spectrometer with a 2048×2048 pixel two-dimensional cooled CCD array is mounted outside the window, and its optical axis is aligned perpendicular to the surface of the deposition substrate using a precision alignment mechanism.

[0063] During the exposure process, the area array detector continuously acquires plasma emission images over 180 seconds at a rate of 20 frames per second. Each pixel records the plasma emission intensity at a specific spatial location, mainly including the emission spectra of carbon-based (CH) and silicon-based (SiH) active species in the 250–450 nm wavelength range.

[0064] Spectral intensity is normalized and calibrated using a standard light source to eliminate differences in instrument response and ensure comparability of spatial intensity distribution.

[0065] After acquiring the two-dimensional emission image, two characteristic emission peaks with center wavelengths of 431 nm (SiH) and 389 nm (CH) were selected, and their spatial integral intensities were normalized per unit time. The normalized light intensity I(x,y) was mapped to the energy irradiation dose distribution D(x,y) using the following conversion model: Where: D(x,y) represents the energy irradiation dose per unit area, in millijoules per square centimeter (mJ / cm²); I(x,y) is the unit normalized luminescence intensity (dimensionless) collected by the area array CCD; t is the excitation time (in seconds), which is 180 seconds in this embodiment; k is the empirical calibration coefficient, with a value of 0.85, which is fitted based on the actual irradiation dose measured in multiple sample tests.

[0066] The conversion result is exported in the form of a two-dimensional matrix with the same spatial resolution as the CCD array (2048×2048), generating a complete D(x,y) data file.

[0067] The obtained plasma irradiation dose function D(x,y) was imported into a two-dimensional finite element model based on the material's thermal-stress coupling mechanism to reconstruct the stress distribution of the silicon carbide thin film. The model parameters were set as follows: Thin film material properties: Silicon carbide thermal expansion coefficient: Young's modulus: 420 GPa; Poisson's ratio: 0.21; Ceramic substrate properties: alumina; Coefficient of thermal expansion: Young's modulus: 380 GPa; The membrane-substrate bonding is assumed to be perfectly adhered. Input source term: D(x,y) is used as the space thermal energy input source term; the initial temperature is set to the deposition temperature (800℃); the equivalent strain-induced relationship between irradiation dose and local film heating effect is considered. The model mesh is constructed using ANSYS Mechanical software, and the least squares error fitting method is used to convert the local thermal input into stress distribution σ(x,y), outputting a two-dimensional equivalent force field.

[0068] To assess the degree of local stress concentration, a stress gradient index Δσ is defined as the difference between the stress maximum and minimum points, expressed in megapascals (MPa). In this embodiment, the initial stress gradient Δσ can reach 78 MPa, and subsequent dynamic compensation is required by modulating the plasma power.

[0069] S500: Based on the region with the largest stress gradient change in D(x,y), implement local power modulation and dynamically adjust the plasma excitation power P(x,y) to achieve stress compensation in the target region, so that the overall stress gradient Δσ is less than 10MPa.

[0070] After obtaining the plasma irradiation dose distribution function D(x,y) and stress distribution function σ(x,y) in step S400, targeted plasma excitation power control is further implemented in local stress concentration areas to form a spatially variable excitation power distribution P(x,y) to compensate for the non-uniform stress distribution within the deposited film. This step completes four key stages—region identification, parameter extraction, modulation calculation, and power control—through spatial analysis and custom parameter modeling of D(x,y) and σ(x,y). The specific implementation is as follows: In this embodiment, the two-dimensional plasma irradiation dose distribution function D(x,y) and the stress distribution function σ(x,y) are first registered in coordinates. Since both have the same spatial sampling resolution (2048×2048 dot matrix), spatial alignment is achieved directly through index mapping.

[0071] The stress gradient change value Δσ(x,y) is then calculated, which is defined as the maximum difference in stress values ​​within a five-point neighborhood centered at each sampling point: If the Δσ(x,y) value at a certain point exceeds a set threshold of 50 MPa, it is marked as a "stress anomaly point". The set of all continuously distributed anomaly points constitutes one or more target regions. To avoid the influence of isolated noise on the judgment results, a morphological closing operation is performed on the marked image to eliminate redundant markings in small regions.

[0072] Finally, N target regions are identified, each defined by its boundary coordinates (x_min, x_max, y_min, y_max), and stored in the region list.

[0073] For each identified target region, it is divided into m×n sub-region units according to the equal spacing rule (m=n=10 in this embodiment), and each unit corresponds to a small local dataset in D(x,y) and σ(x,y).

[0074] The power modulation coefficient γ(i,j) of each unit is calculated as follows: ;in: , , is an empirically determined weighting coefficient; the value of γ(i,j) is controlled between 0.8 and 1.5; if γ(i,j) exceeds the range, it is truncated to the boundary value to prevent over-modulation.

[0075] Among them, the transverse normalized stress increment The calculation method is as follows: Where: σ(i,j) represents the average stress value of the cell in the i-th row and j-th column; σ_avg is the average stress value of the entire target area; This represents the normalized rate of change of stress in the X direction for that cell.

[0076] Among them, the longitudinal irradiation dose gradient coefficient The calculation method is as follows: Where: D(i,j) is the average plasma irradiation dose in this cell; D_ref is the reference irradiation dose in the central sub-region of the target area; This represents the relative intensity of the dose gradient at that point in the Y direction.

[0077] Based on the calculated γ(i,j) modulation coefficients, a power modulation matrix is ​​constructed within the region, corresponding to each sub-region.

[0078] In the experimental setup, a programmable RF power distribution array was used to achieve spatial partitioning excitation. Each sub-region corresponds to an independently controlled RF electrode unit, supporting adjustable RF output power between 20 and 120 watts. For each sub-region, its local RF output power was set as follows: ;in: The base power for the deposition stage is set to 80 W; P(i,j) represents the actual output power of the i×j-th sub-region. Power matrix commands are issued via the device control interface to automatically set the operating power of each sub-region electrode, achieving precise spatial power modulation distribution P(x,y).

[0079] While keeping the temperature (800℃) and pressure (400 mTorr) of the reaction chamber constant, the space variable power mode is activated.

[0080] The plasma excitation process lasts for 180 seconds, during which the modulated region receives targeted energy compensation, thereby inducing local atomic migration, structural relaxation, and micro-strain release.

[0081] After the treatment, Raman spectroscopy and X-ray diffraction residual stress measurement were used again to analyze the stress in the same region. Experimental results show that after power modulation compensation, the regional stress gradient Δσ was significantly reduced to less than 10 MPa, far superior to the untreated sample (Δσ greater than 70 MPa). This step enables the silicon carbide film to exhibit better structural stability and thermal reliability during subsequent thermal cycling or current-excited operation.

[0082] S600: After stress compensation is completed, low-temperature annealing is performed, with the temperature controlled at 600–700℃, to further stabilize the film structure and enhance its interfacial bonding strength.

[0083] After completing the local power modulation and stress compensation treatment described in step S500, a low-temperature heat treatment process is implemented to further release residual micro-stress, stabilize the silicon carbide thin film structure, and improve the interfacial bonding strength between it and the ceramic substrate. This step employs a low-temperature annealing process under a controlled atmosphere, with the temperature controlled within the range of 600–700℃. The specific implementation method is as follows:

[0084] After deposition and stress compensation, the ceramic substrate sample was cooled to room temperature in the reaction chamber, then removed and immediately placed in a clean quartz boat. To avoid interfacial contamination caused by the adsorption of environmental moisture and organic matter, the sample was transferred in a sealed manner under Class 100 cleanroom conditions, with the transfer process not exceeding 10 minutes.

[0085] The annealing process was carried out in a high-purity quartz tube furnace with a heating zone length of 300 mm and a temperature uniformity of ±3℃. To prevent oxidation of the silicon carbide film at high temperatures, high-purity argon (Ar) was selected as the protective atmosphere.

[0086] Gas type: High-purity argon (99.999% purity); Flow rate setting: 200 standard cubic centimeters per minute (sccm); Piping system: All stainless steel gas lines, with molecular sieve dryer and oxygen remover to ensure oxygen content is below 5 ppm.

[0087] After optimization and experimental verification, the following annealing parameters were selected: Heating rate: 10℃ / minute; Holding temperature: 650℃; Holding time: 90 minutes; Cooling method: Natural cooling to room temperature while maintaining argon gas flow.

[0088] This temperature is below the crystallization temperature of silicon carbide thin films (approximately 1000°C), and will not cause abnormal grain growth, but is sufficient to promote the structural rearrangement of atoms at the nanoscale, thereby releasing residual stress and strengthening the diffusion bonding between interfacial atoms.

[0089] The annealed samples were evaluated for their treatment effect using the following methods: Interface bonding strength test: Method: The peel force of the film layer was measured on a micro-load testing machine using the micro-tensile method; Results: The bond strength before treatment was approximately 14 MPa, which increased to 27 MPa after annealing, representing an improvement of approximately 92.8%. Cause analysis: Low-temperature annealing promotes the reconstruction of chemical bonds and the formation of diffusion transition layer between silicon carbide film and ceramic substrate.

[0090] Structural stability characterization: The surface of the film was scanned using Raman spectroscopy to observe the changes in the full width at half maximum (FWHM) of the spectral peaks; FWHM before processing was After treatment, it dropped to This indicates that the stress distribution of the thin film is more uniform and the structure tends to be stable.

[0091] c) Cross-sectional analysis: The sample was cut using a focused ion beam (FIB) and observed using a transmission electron microscope (TEM). A clear transition layer band is visible, with a thickness of approximately 8–12 nm, indicating that a transition bonding layer has been formed between the film and the substrate.

[0092] This annealing step is performed based on the preceding step S500, and the prerequisites it depends on include: Prestressed equilibrium structure generated by plasma power modulation; Stability control of deposition temperature and interface morphology; The accuracy of compensation region identification is determined by the distribution characteristics of D(x,y) and σ(x,y).

[0093] By controlling the annealing temperature within the range of 600–700℃ and introducing an inert protective atmosphere, the structural integrity of silicon carbide thin films during thermal cycling is effectively improved, avoiding failure phenomena such as film cracking and interface peeling during subsequent encapsulation or power-on processes.

[0094] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for depositing plasma-assisted silicon carbide heating elements, characterized in that: include: S100: Provides a ceramic substrate with a micro-nano composite groove structure and places it in a reaction chamber, wherein the surface roughness Ra of the ceramic substrate is <100 nm; S200: Carbon source gas and silicon source gas are introduced into the reaction chamber, and radio frequency plasma with a frequency of 13.56 MHz is applied to form a pre-activated gas mixture to generate an initial nucleophilic layer on the surface of the ceramic substrate, wherein the surface energy of the nucleophilic layer is not less than 50 mN / m. S300: After forming the nucleophilic layer, adjust the temperature of the reaction zone to no higher than 850°C, and introduce the auxiliary gas Ar. Maintaining the plasma state, silicon carbide thin film deposition is performed until the deposition thickness reaches a set value T1, where T1 is less than 2 μm; S400: Obtain the plasma irradiation dose distribution D(x,y) on the surface of the deposited thin film, where D(x,y) is a two-dimensional spatial function used to characterize the local deposition stress distribution; S5 00: Based on the region with the largest stress gradient change in D(x,y), local power modulation is implemented to dynamically adjust the plasma excitation power P(x,y) in order to achieve stress compensation in the target region, so that the overall stress gradient Δσ is less than 10MPa; S600: After stress compensation is completed, low-temperature annealing is performed, with the temperature controlled at 600–700℃, to further stabilize the film structure and enhance its interfacial bonding strength.

2. The plasma-assisted silicon carbide heating element deposition method according to claim 1, characterized in that: in, The micro / nano composite trench structure described in step S100 includes: forming a micrometer-scale trench array with a period of 20 μm and a depth of 2.5 μm by photolithography and reactive ion etching; and forming a density of approximately [missing information - likely a number] on the bottom and sidewalls of the trenches by etching with a nanosphere mask and oxygen plasma. A nanoscale array of pits per cm² with a depth of 200–300 nm.

3. The plasma-assisted silicon carbide heating element deposition method according to claim 2, characterized in that: in, The ceramic substrate mentioned in step S100 is a high-purity dense sintered alumina ceramic sheet with a purity of not less than 99.6% and a surface roughness Ra of 46.2 nm. It is subjected to chemical mechanical polishing and plasma activation treatment. The activation treatment uses pure oxygen gas with a radio frequency power of 100 W, a frequency of 13.56 MHz, and a processing time of 60 seconds.

4. The plasma-assisted silicon carbide heating element deposition method according to claim 1, characterized in that: in, The pre-activated gas mixture in step S200 consists of methane gas and silane gas, with gas flow rates of 30 sccm and 10 sccm, respectively. The plasma excitation time is 120 seconds, and the plasma is a 13.56 MHz radio frequency plasma with an initial power of 80 W and an excitation mode of continuous wave mode.

5. The plasma-assisted silicon carbide heating element deposition method according to claim 1, characterized in that: in, The auxiliary gases in step S300 are argon and hydrogen, with flow rates of 80 sccm and 50 sccm, respectively. The deposition rate of the silicon carbide thin film is 12 nm / min, and the final deposition thickness T1 is controlled between 800 nm and 1.5 μm.

6. The plasma-assisted silicon carbide heating element deposition method according to claim 5, characterized in that: in, In step S300, the substrate tray is cleaned every 20 minutes during the deposition process. Rotational reversal operation.

7. The plasma-assisted silicon carbide heating element deposition method according to claim 1, characterized in that: in, In step S400, D(x,y) is determined by setting up a planar array spectral acquisition device at the top of the reaction chamber, and using an energy irradiation conversion model based on the normalized integral intensity of the plasma luminescence intensity in the two bands of 431 nm and 389 nm. The calculations show that k is 0.85, t is 180 seconds, D(x,y) represents the energy irradiation dose per unit area, and I(x,y) is the unit normalized luminous intensity collected by the area array CCD.

8. The plasma-assisted silicon carbide heating element deposition method according to claim 1, characterized in that: wherein, The plasma excitation power P(x,y) mentioned in step S500 is calculated as follows: First, identify regions where the stress gradient Δσ(x,y) exceeds 50 MPa; then calculate the transverse normalized stress increment in these regions. With longitudinal irradiation dose gradient coefficient Final power modulation coefficient and will , It is 80 W.

9. The plasma-assisted silicon carbide heating element deposition method according to claim 8, characterized in that: in, The spatial partitioned radio frequency power modulation described in step S500 is achieved by controlling the output power of each sub-region in the radio frequency power array. The output power range is 20–120 watts, and the modulation target is to reduce the overall stress gradient Δσ of the thin film to below 10 MPa.

10. The plasma-assisted silicon carbide heating element deposition method according to claim 1, characterized in that: in, The low-temperature annealing process in step S600 is carried out at 650°C for 90 minutes. The atmosphere used is high-purity argon gas with a purity of not less than 99.999% and a flow rate of 200 sccm. The gas is then naturally cooled to room temperature in an inert atmosphere.

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