A quartz furnace tube for semiconductor heat treatment and a method for manufacturing the same

Abstract

The application discloses a quartz furnace tube for semiconductor heat treatment, which comprises a cylindrical tube body made of quartz glass, a multilayer gradient composite coating arranged on the inner wall of the cylindrical tube body, and the multilayer gradient composite coating comprises, from inside to outside, a transition layer, a functional layer and a surface layer. The application solves the thermal expansion matching problem between the coating and the quartz substrate through gradient composition design, dynamically generates a protective layer by using sacrificial nanoparticles to react with process gas during high-temperature process, realizes in-situ self-repairing of the coating, and the porous surface layer can capture particles generated during the process. The application can significantly prolong the service life of the quartz furnace tube, improve the wafer heat treatment uniformity, reduce particle pollution, and is suitable for diffusion, oxidation, annealing and other heat treatment processes in integrated circuit manufacturing.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, specifically to a quartz furnace tube for semiconductor heat treatment and its preparation method, which is particularly suitable for high-temperature heat treatment processes such as diffusion, oxidation, and annealing in integrated circuit manufacturing. Background Technology

[0002] Semiconductor heat treatment is a core process in integrated circuit manufacturing, and quartz furnace tubes are key equipment in this process. Heat treatment is one of the critical steps in integrated circuit manufacturing, mainly including diffusion, oxidation, annealing, and alloying. These processes are typically carried out in high-temperature furnace tubes, which require maintaining a high-purity process atmosphere and precise temperature control.

[0003] Quartz furnace tubes are widely used in semiconductor heat treatment equipment due to their excellent high-temperature stability, chemical inertness, and low coefficient of thermal expansion. Several technical solutions for quartz furnace tubes have been disclosed in the prior art. For example, Chinese utility model patent CN2540079Y discloses a quartz furnace tube in which a high-temperature resistant material coating (such as alumina) is melted and coated on the outer surface of the heated part of the quartz substrate to increase the operating temperature of the furnace tube. However, this technical solution has the following shortcomings: First, the coating is only applied to the outer surface and cannot protect the inner wall of the furnace tube from corrosion by process gases; second, the coating is a single material and does not consider the difference in thermal expansion coefficients between the coating and the quartz substrate, making it prone to thermal stress during high-temperature cycling, leading to coating cracking and peeling; finally, once the coating is damaged, it cannot repair itself, resulting in a limited service life. For example, Chinese utility model patent CN213599825U discloses a quartz furnace tube for a large-diameter diffusion furnace with heat insulation at the head. It features a silica coating on the outer surface of the quartz tube as a stabilizing layer to increase the tube's strength. However, this technical solution also suffers from problems such as a simple coating structure, poor thermal matching, and lack of self-healing function.

[0004] In summary, the existing quartz furnace tubes still have the following technical problems: The coefficient of thermal expansion of quartz is approximately 0.5 × 10⁻⁶. -6 / K, while the coefficient of thermal expansion of commonly used coating materials such as SiC is approximately 3.5×10. -6 / K, and there is a significant difference between the two. During high-temperature heat treatment, enormous thermal stress is generated between the coating and the quartz substrate, causing the coating to crack, peel off, and lose its protective function. Existing technologies typically use a single coating, without considering the matching of thermal expansion coefficients, resulting in a limited coating lifespan.

[0005] During long-term high-temperature processes, coatings inevitably suffer damage and wear, leading to microcracks or localized peeling. Existing coatings, once damaged, cannot self-repair, exposing the quartz substrate to process gases, causing particulate contamination, and ultimately requiring furnace tube replacement. Statistics show that conventional quartz furnace tubes need replacement after 1000-2000 hours of continuous operation, severely impacting production efficiency.

[0006] The inner wall of a quartz furnace tube reacts with process gases (such as O2, H2, Cl2, HCl, etc.) at high temperatures, generating volatile products such as SiO2 and SiCl4, as well as nanoscale particles. These particles adhere to the wafer surface, causing device defects and reducing the yield of integrated circuits. As the feature size of integrated circuits continues to shrink (currently below 5nm), the requirements for controlling particulate contamination are becoming increasingly stringent, and traditional quartz furnace tubes can no longer meet these requirements.

[0007] The uniformity of temperature distribution inside the furnace tube directly affects the consistency of the heat treatment process. Traditional temperature measurement methods use multi-point thermocouples, but the number of thermocouples is limited, the response is lagging, and continuous distributed measurement cannot be achieved, making it difficult to accurately control the temperature distribution inside the furnace tube.

[0008] Therefore, developing a quartz furnace tube that can solve the above problems is of great significance to the field of integrated circuit manufacturing. Summary of the Invention

[0009] The purpose of this invention is to overcome the defects in the prior art and provide a quartz furnace tube for semiconductor heat treatment, which overcomes the defects in the prior art such as coating cracking due to mismatch in thermal expansion coefficients, irreparable coating damage, serious particulate contamination, and difficulty in accurately controlling temperature uniformity.

[0010] To achieve the above objectives, the technical solution of the present invention is to design a quartz furnace tube for semiconductor heat treatment, comprising: The cylindrical tube is made of quartz glass. A multi-layer gradient composite coating is disposed on the inner wall of the cylindrical tube. The multi-layer gradient composite coating comprises, from the inside out: The transition layer is composed of silicon-oxygen-carbon material. The carbon content of the transition layer increases gradually from the inner surface to the outer surface along the thickness direction, so that the coefficient of thermal expansion increases gradually from the quartz matrix side to the functional layer side. A functional layer is disposed on the outer surface of the transition layer and is composed of a SiC matrix or a Si3N4 matrix and sacrificial nanoparticles dispersed in the matrix. The sacrificial nanoparticles react with the process gas under high-temperature process conditions to generate an oxide protective layer. The surface layer, disposed on the outer surface of the functional layer, is a porous SiO2 layer.

[0011] A further technical solution is that the sacrificial nanoparticles are selected from at least one of Si, AlN, and Si3N4, with a particle size of 10-100 nm, and the volume fraction of the sacrificial nanoparticles in the functional layer is 5%-20%.

[0012] A further technical solution is that the thickness of the transition layer is 0.5-2μm, the thickness of the functional layer is 2-5μm, and the thickness of the surface layer is 0.2-0.5μm.

[0013] A further technical solution is to reduce the coefficient of thermal expansion of the transition layer from 0.5 × 10⁻⁶ along the thickness direction. -6 The / K gradient was increased to 3.5 × 10. -6 / K.

[0014] A further technical solution is to have a surface layer with a porosity of 30%-50% and a pore size of 5-50nm.

[0015] A further technical solution is to install a fiber Bragg grating array on the outer wall surface of the cylindrical tube along the axial direction to monitor the axial temperature distribution of the furnace tube in real time.

[0016] A fiber Bragg grating array is composed of multiple fiber Bragg gratings arranged at intervals along the axial direction of the tube in series.

[0017] The present invention also provides a method for preparing a quartz furnace tube for semiconductor heat treatment, comprising the following steps: (1) Transition layer deposition: A silicon-oxygen-carbon transition layer is deposited on the inner wall of the quartz tube by chemical vapor deposition. During the deposition process, the flow ratio of silicon-containing precursor gas to carbon-containing precursor gas is controlled to increase with time, so that the carbon content of the transition layer increases gradually from the inside to the outside along the thickness direction. (2) Functional layer deposition: Chemical vapor deposition is used to introduce silicon-containing precursor gas and carbon-containing precursor gas, or silicon-containing precursor gas and nitrogen-containing precursor gas, and sacrificial nanoparticles are introduced to deposit a SiC or Si3N4 functional layer containing sacrificial nanoparticles on the surface of the transition layer. (3) Surface layer formation: A porous SiO2 surface layer is formed on the surface of the functional layer by using the sol-gel method or plasma-enhanced chemical vapor deposition method; (4) High-temperature heat treatment: High-temperature heat treatment is carried out in an inert atmosphere to form chemical bonds between the layers.

[0018] A further technical solution is that the silicon-containing precursor gas in step (1) is silane, the carbon-containing precursor gas is methane, ethane or ethylene, the deposition temperature is 800-1000℃, and the deposition pressure is 10-100Pa.

[0019] Silanes can be dichlorosilanes.

[0020] A further technical solution is that the sacrificial nanoparticles in step (2) are introduced into the reaction chamber by aerosol delivery, the carrier gas of the particles is argon or nitrogen, the deposition temperature is 900-1100℃, and the deposition pressure is 50-200Pa.

[0021] A further technical solution is that the temperature of the high-temperature heat treatment in step (4) is 1000-1200℃, the holding time is 1-4 hours, and the atmosphere is argon or nitrogen.

[0022] The advantages and beneficial effects of this invention are: it solves the problem of matching thermal expansion coefficients, enables in-situ self-repair of the coating, reduces particulate contamination, achieves precise temperature control, and has significant overall effects.

[0023] This invention achieves a lower coefficient of thermal expansion from the quartz matrix (0.5 × 10⁻⁶) by setting a silicon-oxygen-carbon transition layer and gradually increasing the carbon content along the thickness direction. -6 / K) to the functional layer (3.5×10 -6 The gradient transition ( / K) eliminates the abrupt change in thermal stress at the interface of traditional single coatings, effectively preventing the coating from cracking and peeling during temperature cycling, and significantly improving the bonding strength and durability of the coating.

[0024] This invention disperses sacrificial nanoparticles (such as Si, AlN, etc.) in the functional layer. These nanoparticles react with process gases (such as O2, H2O, NH3, etc.) during high-temperature processing, dynamically generating an oxide or nitride protective layer. This fills microcracks and localized damage areas in the coating, achieving in-situ self-repair of the coating. Compared with traditional static coatings, the self-repair function of this invention can significantly extend the effective protection time of the coating, and the service life of the quartz furnace tube can be extended to more than 10,000 hours.

[0025] This invention features a porous SiO2 surface layer with a porosity of 30%-50% and a pore size of 5-50 nm, effectively capturing nanoscale particles generated during the process and preventing them from falling into the wafer area. Simultaneously, the surface layer itself is composed of high-purity SiO2, thus avoiding the introduction of additional contaminants. Experiments show that after 1000 hours of continuous operation, the gas particle concentration (particle size ≥ 0.1 μm) inside the quartz furnace tube of this invention is ≤ 0.1 particles / cm³. 3 This is far lower than existing technologies (approximately 50 particles / cm). 3 ).

[0026] This invention embeds a fiber Bragg grating array into the wall of a quartz furnace tube, enabling continuous distributed temperature measurement along the furnace tube axis with a spatial resolution of up to 1 cm and a response time of ≤1 second. Combined with a temperature control system to form a closed-loop control, the axial temperature deviation within the furnace tube can be controlled within ±0.5℃, significantly superior to existing technologies (±5℃), thus improving the consistency of the heat treatment process.

[0027] The present invention solves the thermal matching problem with the transition layer, provides chemical barrier and self-healing functions with the functional layer, and realizes particle capture with the surface layer. The three work together to achieve a comprehensive improvement in the service life, process cleanliness and temperature uniformity of quartz furnace tubes. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a first embodiment of a quartz furnace tube for semiconductor heat treatment according to the present invention; Figure 2 yes Figure 1 Cross-sectional view; Figure 3 yes Figure 2 A magnified view of the central elliptical portion.

[0029] In the figure: 1. Tubular body; 2. Transition layer; 3. Functional layer; 4. Surface layer; 5. Sacrificial nanoparticles; 7. Fiber Bragg grating array. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1: As Figures 1 to 3 As shown, the present invention provides a quartz furnace tube for semiconductor heat treatment and its preparation method. 1. Quartz Furnace Tube Structure like Figure 1 , Figure 2 As shown, the quartz furnace tube for semiconductor heat treatment in this embodiment includes: a cylindrical tube body 1, a multilayer gradient composite coating disposed on the inner wall of the cylindrical tube body 1, and a fiber Bragg grating array 7 embedded in the tube wall of the cylindrical tube body 1.

[0032] The cylindrical tube 1 is made of high-purity quartz glass with a purity of ≥99.999%, an inner diameter of 300mm, a wall thickness of 5mm, and a length of 1500mm. It is suitable for heat treatment processes of 6-inch to 8-inch wafers.

[0033] like Figure 3As shown, the multi-layer gradient composite coating, from the inside out (here, "from the inside out" follows the directional definition in coating technology, with the substrate, i.e., the quartz tube wall, as the "inside," and the coating surface, i.e., the surface in contact with the furnace, as the "outside"; the inside and outside here are not the "inside" of the aforementioned cylindrical tube inner wall; or in other words, the multi-layer gradient composite coating includes, sequentially from the quartz substrate side to the furnace side): Transition layer 2: Composed of silicon-oxygen-carbon material, 1 μm thick, with carbon content gradually increasing from the inner surface to the outer surface along the thickness direction, and a coefficient of thermal expansion from 0.5 × 10⁻ 6 The / K gradient is increased to 3.5 × 10⁻ 6 / K; Functional layer 3: It consists of a SiC matrix and sacrificial nanoparticles 5 dispersed therein, with a thickness of 3μm. The sacrificial nanoparticles 5 are Si nanoparticles with a particle size of 50nm and a volume fraction of 10%. Surface layer 4: Porous SiO2 layer, thickness 0.3μm, porosity 40%, pore size 20nm.

[0034] like Figure 3 As shown, the fiber Bragg grating array 7 is spirally embedded in the tube wall along the axial direction of the cylindrical tube 1, with an adjacent grating spacing of 10 mm and a total of 150 grating points, which can realize continuous axial temperature monitoring of the furnace tube.

[0035] 2. Preparation method The method for preparing a quartz furnace tube for semiconductor heat treatment with a self-healing gradient coating according to this embodiment includes the following steps: (1) Transition layer deposition A silicon-oxygen-carbon transition layer was deposited on the inner wall of the quartz tube using chemical vapor deposition (CVD). Deposition process parameters: Silicon-containing precursor gas: silane (SiH4), flow rate 100 sccm (standard cubic centimeters per minute); Carbon-containing precursor gas: ethylene (C2H4), initial flow rate 10 sccm, linearly increasing to 100 with time; Oxygen source: Oxygen (O2), flow rate 5 sccm, constant; Deposition temperature: 900℃; Deposition pressure: 50 Pa; RF power: 200W; Deposition time: 30 minutes.

[0036] During deposition, by controlling the ethylene flow rate to increase over time, the carbon content of the transition layer gradually increases along the thickness direction, resulting in a gradient change in the coefficient of thermal expansion. Simultaneously, the oxygen flow rate is kept constant, ensuring a relatively stable oxygen content during deposition. Oxygen acts as the oxygen source, reacting with silane and ethylene to form SiOC (silicon-oxygen-carbon) material. By controlling the oxygen flow rate to remain constant, the oxygen content in the transition layer remains relatively uniform, while the gradient change in carbon content dominates the gradient transition of the coefficient of thermal expansion. The specific process is as follows: 0-10 minutes: Low ethylene flow rate (10-40 sccm), forming a low-carbon content layer with a coefficient of thermal expansion of approximately 0.8 × 10⁻⁻⁻⁶. 6 / K, with the quartz matrix (approximately 0.5 × 10⁻ 6 / K) matching; 10-20 minutes: moderate ethylene flow (40-60 sccm), forming a medium carbon content layer with a thermal expansion coefficient of approximately 2.0 × 10⁻ 6 / K, serving as an intermediate transition layer; 20-30 minutes: ethylene flow rate is high (70-100 sccm), forming a high-carbon content layer with a thermal expansion coefficient of approximately 3.2 × 10⁻ 6 / K, and the functional layer (approximately 3.5 × 10⁻ 6 / K) matches.

[0037] The coefficient of thermal expansion (CTE) of silicon-oxygen-carbon (SiOC) materials can be controlled by adjusting their carbon content. Studies have shown that when the free carbon volume fraction in SiOC is below 10-15%, the CTE increases with increasing carbon content; when the free carbon content exceeds this threshold, the CTE can be stably maintained at approximately 3.2 × 10⁻⁻⁻⁻⁶. 6 / K, which is close to the thermal expansion characteristics of SiC materials.

[0038] The transition layer of this invention uses SiOC material. During chemical vapor deposition, the flow rate gradient of the carbon-containing precursor gas (such as ethylene) is controlled to increase gradually, causing the carbon content of the transition layer to gradually increase from the inside to the outside along the thickness direction. A low carbon content (free carbon <5 vol%) is maintained near the quartz substrate, and the CTE is close to that of quartz (0.8 × 10⁻⁻⁻⁶). 6 / K); a high carbon content (free carbon > 12 vol%) is maintained near the functional layer side, and the CTE increases to 3.2 × 10⁻ 6 / K, with SiC functional layers (3.5×10⁻ 6 / K) good match. Gradient design eliminates abrupt changes in thermal stress at the interface.

[0039] (2) Functional layer deposition A SiC functional layer containing sacrificial nanoparticles was deposited on the surface of the transition layer using chemical vapor deposition (CVD). Deposition process parameters: Silicon-containing precursor gas: silane (SiH4), flow rate 150 sccm; Carbon-containing precursor gas: methane (CH4), flow rate 200 sccm; Sacrificial nanoparticles: Si nanoparticles, 50 nm in diameter, introduced via aerosol delivery; Aerosol preparation: Si nanoparticles were dispersed in ethanol at a concentration of 10 g / L and ultrasonically dispersed for 30 minutes; Atomization parameters: atomizer frequency 1.7MHz, carrier gas argon flow rate 80sccm; Deposition temperature: 1000℃; Deposition pressure: 100 Pa; Deposition time: 60 minutes.

[0040] Si nanoparticles are dispersed in a solvent to form a suspension, which is then atomized to form an aerosol. This aerosol, along with gaseous silane and methane precursors, is transported to the reaction chamber. Upon reaching the heated substrate (transition layer) surface, the ethanol solvent in the aerosol droplets rapidly evaporates, releasing the Si nanoparticles. Simultaneously, the silane and methane decompose at high temperature, reacting to form SiC. SiC is deposited on the transition layer surface to form a matrix, while the Si nanoparticles are embedded within the SiC matrix, forming a SiC functional layer containing sacrificial nanoparticles.

[0041] The volume fraction of nanoparticles in the deposited coating can be controlled by adjusting the concentration of nanoparticles in the aerosol (e.g., 10 g / L) and the ratio of the atomizing carrier gas flow rate (e.g., 80 sccm) to the precursor gas flow rate (e.g., silane 150 sccm). Experiments have shown that under the aforementioned deposition conditions (temperature 1000℃, pressure 100 Pa, silane flow rate 150 sccm, methane flow rate 200 sccm), when the concentration of Si nanoparticle aerosol is 10 g / L and the atomizing carrier gas (argon) flow rate is 80 sccm, the volume fraction of Si nanoparticles in the resulting functional layer is approximately 10%. By linearly adjusting the aerosol concentration or carrier gas flow rate, the volume fraction can be controlled within the range of 5%-20%. Under these conditions, approximately 10% Si nanoparticles by volume are uniformly dispersed in the SiC matrix.

[0042] For Si nanoparticles: the reaction generates SiO2, accompanied by a volume expansion of about 120%, and the expansion products compress the crack walls to form a tight seal. For AlN nanoparticles: the reaction produces α-Al2O3, which has extremely high chemical stability and density.

[0043] Meanwhile, the newly generated SiO2 is in a viscous flow state at high temperature, which can further wet and fill the crack interface. After cooling, it forms a strong ceramic bond, thereby achieving in-situ repair of cracks and preventing gas from further eroding the matrix.

[0044] When microcracks develop in the functional layer due to thermal stress, high-temperature process gases (such as O2 or H2O) seep in along the cracks. Since the Gibbs free energy change (ΔG, the difference in free energy before and after the reaction, used to determine whether the reaction can proceed spontaneously) of the sacrificial nanoparticles (Si or AlN) is much lower than that of the SiC / Si3N4 matrix, the nanoparticles will preferentially undergo oxidation.

[0045] (3) Surface layer formation A porous SiO2 surface layer was formed on the surface of the functional layer using the sol-gel method. Specific steps: Preparation of SiO2 sol: Tetraethyl orthosilicate, ethanol, water and hydrochloric acid were mixed in a molar ratio of 1:5:2:0.01 and stirred for 2 hours; Add template agent: Add polyethylene glycol (molecular weight 1000) at 20% of the molar amount of tetraethyl orthosilicate; Coating: Apply the sol evenly to the surface of the functional layer; Drying: Dry at 80℃ for 2 hours; Calcination: Calcination at 500℃ for 1 hour removes the template agent and forms a porous structure.

[0046] As usage time increases, the porous surface layer will gradually be filled with particles. At this point, the trapped particles can be removed by periodic high-temperature oxygen cleaning (e.g., 1100℃, with a small amount of HCl introduced under O2 atmosphere) to restore the porous structure of the surface layer.

[0047] (4) High-temperature heat treatment A cylindrical tube with multiple layers of coating is placed in a high-temperature furnace and held at 1100℃ for 2 hours for high-temperature heat treatment in an argon atmosphere, so that chemical bonds are formed between the layers, thereby improving the bonding strength of the coating.

[0048] (5) Fiber Bragg grating embedding: The fiber Bragg grating array is embedded into the tube wall along the axial direction of the cylindrical tube, with an embedding depth of 1 / 3 of the tube wall thickness. In this embodiment, the fiber Bragg grating array is embedded using the tube slot embedding method, specifically including the following steps: (5.1) Grooving: Using laser processing or mechanical processing, a spiral groove is processed along the axial direction on the outer wall of the quartz furnace tube. The groove width is 0.3-0.5mm, the depth is 1 / 3 of the tube wall thickness (i.e., 1-2mm), and the axial distance between two adjacent spiral grooves is 10-20mm (the spatial sampling interval, i.e., the interval between the center points of adjacent gratings along the tube axis, is 10-20mm). (5.2) Grating prefabrication: Select a high-temperature resistant fiber Bragg grating (which can withstand temperatures above 1000℃), and write a grating dot at intervals of 10-20mm along the fiber axis, for a total of 150 grating dots to form a fiber grating array; In this embodiment, the high-temperature resistant fiber Bragg grating adopts a regenerative Bragg grating (RBG), which can work at 1200℃ after high-temperature annealing and can work stably for a long time in the high-temperature environment of semiconductor heat treatment process.

[0049] (5.3) Embedding: Place the prefabricated fiber grating array in the groove so that each grating point is aligned with the preset temperature measurement position; (5.4) Fixing: The groove is filled with quartz glass powder slurry and the fiber grating array is fixed in the groove; (5.5) Curing / Sintering: Curing at 200-300℃ for 2 hours (when using inorganic adhesive), or sintering at 1000-1100℃ for 1 hour (when using quartz glass powder slurry) to make the filler material form a strong bond with the quartz tube wall; (5.6) Surface finishing: Polish the surface after curing / sintering to make the fiber grating array flush with the outer wall of the quartz furnace tube.

[0050] (6) Component installation An air inlet and an air outlet are installed at both ends of the cylindrical tube, and a temperature control system is connected to them.

[0051] 3. Performance Testing (1) Thermal cycling test The quartz furnace tube prepared in this embodiment was placed in a heat treatment device and subjected to thermal cycling tests between room temperature and 1100°C. Each cycle included heating (30 minutes), holding (2 hours), and cooling (30 minutes), for a total of 500 cycles.

[0052] Test results showed that after 500 thermal cycles, the coating surface showed no cracking or peeling, and the coating bonded well to the quartz substrate. The control sample (single SiC coating) showed obvious cracks after 100 thermal cycles, and the coating peeled off over a large area after 200 thermal cycles.

[0053] (2) Particulate pollution test A laser particle counter was used to detect the concentration of gas particles inside the furnace tube. The system was operated continuously for 1000 hours at 1100℃ in an oxygen atmosphere, with samples taken every 100 hours.

[0054] Test results show that after 1000 hours of operation, the concentration of gas particles (particle size ≥ 0.1 μm) inside the furnace tube is ≤ 0.1 particles / cm³, which is much lower than that of uncoated quartz furnace tubes (approximately 50 particles / cm³) and quartz furnace tubes with a single coating (approximately 5 particles / cm³).

[0055] (3) Temperature uniformity test The axial temperature distribution of the furnace tube is monitored in real time using a fiber Bragg grating array, and closed-loop control is performed in conjunction with the temperature control system.

[0056] Test results show that at the set temperature of 1100℃, the axial temperature deviation inside the furnace tube is ≤±0.5℃. In comparison, using traditional thermocouple temperature measurement, the axial temperature deviation is approximately ±5℃.

[0057] (4) Service life test It operates continuously at 1100℃ in an oxygen atmosphere, monitoring the status of the furnace tubes until failure.

[0058] Test results show that the quartz furnace tube in this embodiment has a service life of over 12,000 hours. The comparative example (uncoated) has a service life of approximately 800 hours, and the comparative example (single SiC coating) has a service life of approximately 2,500 hours.

[0059] This quartz furnace tube for semiconductor heat treatment, featuring a self-healing gradient coating, can be used in heat treatment equipment for integrated circuit manufacturing. The heat treatment equipment for integrated circuit manufacturing also includes a temperature control system connected to a fiber Bragg grating array. The temperature control system adjusts the output power of the heating element based on the temperature distribution signal fed back from the fiber Bragg grating array, achieving closed-loop control of the temperature distribution within the furnace tube.

[0060] Example 2: The difference from Example 1 is that the functional layer is a Si3N4 matrix, and the sacrificial nanoparticles are AlN nanoparticles with a particle size of 30 nm and a volume fraction of 15%. The deposition process parameters are as follows: the silicon-containing precursor gas is silane with a flow rate of 100 sccm; the nitrogen-containing precursor gas is ammonia with a flow rate of 200 sccm; the sacrificial nanoparticles are AlN nanoparticles with a particle size of 30 nm, introduced via aerosol delivery (same as in Example 1); the deposition temperature is 1050℃; the deposition pressure is 80 Pa; and the deposition time is 60 minutes.

[0061] Tests showed that the coating did not crack after 500 thermal cycles; the particle concentration was ≤0.08 particles / cm³ after 1000 hours of operation; the axial temperature deviation was ≤±0.4℃; and the service life exceeded 15000 hours.

[0062] Example 3: This example is basically the same as Example 1, except that: The transition layer has a thickness of 1.5 μm, the functional layer has a thickness of 4 μm, and the surface layer has a thickness of 0.4 μm. The surface layer was prepared by plasma-enhanced chemical vapor deposition and has a porosity of 45%.

[0063] The deposition process parameters are as follows: the silicon precursor is hexamethyldisiloxane with a flow rate of 50 sccm; the oxygen source is oxygen with a flow rate of 200 sccm; the deposition temperature is 200℃; the deposition pressure is 50 Pa; the microwave power is 500 W; and the deposition time is 10 minutes.

[0064] Tests showed that the coating did not crack after 500 thermal cycles; the particle concentration was ≤0.05 particles / cm³ after 1000 hours of operation; the axial temperature deviation was ≤±0.3℃; and the service life exceeded 18000 hours.

[0065] Comparative Example 1 This comparative example uses a commercially available standard quartz furnace tube, without any coating or fiber optic grating.

[0066] After testing, the particle concentration was approximately 50 particles / cm³ after 1000 hours of operation; the axial temperature deviation was approximately ±5℃; and the service life was approximately 800 hours.

[0067] Comparative Example 2 This comparative example uses a quartz furnace tube with a single SiC coating, 3μm thick, without a transition layer, self-healing function, or porous surface layer.

[0068] Tests showed that the coating developed cracks after 200 thermal cycles; the particle concentration was approximately 5 particles / cm³ after 1000 hours of operation; the axial temperature deviation was approximately ±4℃; and the service life was approximately 2500 hours.

[0069] As can be seen from the above results, the present invention effectively solves problems such as matching thermal expansion coefficient, self-repair of coating damage, and control of particulate contamination through multi-layer gradient composite coating design. At the same time, it achieves precise temperature control in conjunction with fiber optic grating temperature control system, and its overall performance is significantly better than that of the prior art.

[0070] Example 4: The difference from Example 1 is that, before depositing the multilayer gradient composite coating, a controllable crystallization pretreatment was performed on the quartz furnace tube substrate. The specific steps are as follows: Quartz furnace tube substrate pretreatment: The quartz furnace tube substrate (i.e., the cylindrical tube) was placed in a high-temperature heat treatment furnace and subjected to controllable crystallization heat treatment under a nitrogen atmosphere. The temperature was increased from room temperature to 1200℃ at a heating rate of 5℃ / min; it was held at 1200℃ for 4 hours to precipitate nanoscale cristobalite crystals on the surface of the quartz furnace tube substrate; and it was cooled to room temperature at a cooling rate of 10℃ / min. Characterization by X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that cristobalite crystals with a particle size of approximately 50nm were dispersed in the surface layer (approximately 30μm deep) of the quartz furnace tube substrate, with a volume fraction of approximately 10%. A multi-layer gradient composite coating is deposited on the inner wall of the quartz furnace tube substrate that has undergone controllable crystallization pretreatment. The transition layer, functional layer and surface layer are deposited sequentially according to steps (1)-(3) of Example 1. The specific process parameters are the same as those in Example 1.

[0071] The quartz furnace tube prepared in this embodiment was compared with the control example (i.e., Example 1) without crystallization pretreatment:

[0072] In the quartz furnace tube matrix after controlled crystallization pretreatment, nano-sized cristobalite crystals are uniformly dispersed within the quartz glass matrix. The thermal expansion coefficient of these nanocrystals is approximately 12-18 × 10⁻⁻⁻⁴. 6 / K) is significantly higher than the surrounding quartz glass matrix (approximately 0.5 × 10⁻ 6 / K), which generates a local compressive stress field during the cooling process.

[0073] The results show that, through controlled crystallization pretreatment, this embodiment significantly improves the fracture toughness and interfacial bonding strength of the quartz matrix while maintaining the integrity of the coating, thereby further extending the service life of the quartz furnace tube.

[0074] This embodiment breaks through technical bias. Traditionally, crystallization is considered the cause of failure. This invention adopts reverse thinking and transforms it into an enhancement mechanism. Instead, through crystallization treatment, nanoscale cristobalite crystals (20-100nm) are dispersed in the quartz matrix, achieving the beneficial effects of interfacial stress adjustment and matrix toughening.

[0075] This embodiment achieves the following technical effects through controllable crystallization pretreatment: ① Interface stress adjustment During the cooling process following the deposition of multiple layers of coating, the high expansion characteristics of the nano-cubic quartz crystals generate compressive stress, which counteracts the tensile stress generated by coating shrinkage. Finite element simulation showed that the maximum tensile stress at the interface decreased from approximately 120 MPa in the control example (i.e., Example 1) to approximately 50 MPa, a reduction of approximately 58%.

[0076] ② Matrix toughening The dispersed nanocrystals act as pinning agents for crack propagation: when a crack propagates to the nanocrystals, it needs to bypass or pass through the crystals, consuming more fracture energy. Three-point bending tests show that after controlled crystallization pretreatment, the fracture toughness of the quartz matrix increased from 0.8 MPa·m¹ / ² in the control example to 1.2 MPa·m¹ / ², an increase of approximately 50%.

[0077] ③ Turn harm into benefit Traditional technologies consider quartz crystallization to be the main cause of furnace tube failure, believing that crystallization leads to cracking. This embodiment, by precisely controlling the degree of crystallization (grain size ≤100nm, volume fraction ≤20%), transforms crystallization from a failure mode into an enhancement mechanism, achieving a breakthrough against the biases of traditional technologies.

[0078] Example 5: The difference from Example 1 is that this example further utilizes the surface softening characteristics of the quartz furnace tube under high-temperature heat treatment process to achieve self-cleaning of particulate contaminants on the inner wall.

[0079] The self-cleaning mechanism is as follows: In semiconductor heat treatment processes, quartz furnace tubes typically operate at high temperatures of 1000-1200℃. Within this temperature range, the viscosity of the quartz material decreases significantly (approximately 10). 6 -10 8 At Pa·s, micron-level viscous flow occurs on the surface. When particulate contaminants (such as process byproducts like SiO2, SiC, and Si3N4) adhere to the inner wall of the quartz furnace tube, the difference in thermal expansion coefficients between the particles and the quartz matrix (quartz: approximately 0.5 × 10⁻⁻⁻⁶ Pa·s) leads to this flow. 6 / K, SiC: approximately 3.5 × 10⁻ 6 / K, Si3N4: approximately 3.5 × 10⁻ 6 During temperature cycling, thermal stress is generated at the interface between the SiC particles and the matrix. Calculations show that when the temperature drops from 1000℃ to room temperature, the thermal stress at the interface between the SiC particles and the quartz matrix can reach hundreds of megapascals, which is sufficient to cause the particles to peel off from the matrix surface.

[0080] In this embodiment, the self-cleaning process of the quartz furnace tube during the heat treatment process is as follows: (1) Particle adhesion: During the process, a small number of by-product particles (particle size 0.1-5μm) adhere to the inner wall of the quartz furnace tube (including the surface layer); (2) Thermal stress accumulation: During the process temperature cycle (heating → heat preservation → cooling), the difference in thermal expansion between the particles and the quartz matrix causes repeated thermal stress at the interface; (3) Particle peeling: When the thermal stress exceeds the interfacial bonding strength between the particles and the matrix, the particles automatically peel off from the surface layer; (4) Particle discharge: The peeled particles are blown away by process gases (such as N2, Ar, O2, etc.) and discharged from the furnace tube with the exhaust gas, or captured by the porous surface layer.

[0081] The self-cleaning mechanism of this embodiment works synergistically with the porous surface layer of Embodiment 1: the porous surface layer (porosity 30%-50%, pore size 5-50nm) actively captures smaller nano-sized particles (<0.1μm); the high-temperature softening and peeling mechanism mainly acts on larger micron-sized particles (0.1-5μm); the combination of the two achieves comprehensive control of particulate contaminants of different particle sizes. Testing showed that after 1000 hours of continuous operation, the gas particle concentration (particle size ≥0.1μm) inside the quartz furnace tube of this embodiment was ≤0.03 particles / cm³, which is superior to ≤0.1 particles / cm³ in Embodiment 1, and no tube sagging or dimensional instability due to softening deformation was observed.

[0082] High-temperature heat treatment gives the quartz matrix a stable microstructure, ensuring that it has a 10% stability within the 1000-1200℃ range.6 -10 8 The surface viscosity of Pa·s avoids tube sagging and deformation while ensuring effective particle stripping.

[0083] Example 6: This example is basically the same as Example 1, except that: during the fiber Bragg grating embedding process, the micro-region stress field generated by fiber embedding is used to simultaneously induce the formation of nanoscale cristobalite crystals around the fiber in the quartz matrix, thus achieving the integration of fiber encapsulation and matrix toughening. The fiber embedding step and the high-temperature heat treatment step of coating are combined.

[0084] The specific steps for fiber grating embedding and stress-induced crystallization are as follows: (1) Grooving A spiral groove was machined axially on the outer wall of the quartz furnace tube using laser processing. The process parameters were as follows: laser power of 10W, scanning speed of 5mm / s, groove width of 0.4mm, groove depth of 1 / 3 of the tube wall thickness (approximately 1.5mm), and axial distance between two adjacent spiral grooves of 15mm. (2) Grating prefabrication High-temperature resistant regenerative Bragg gratings (RBGs) are selected, capable of withstanding temperatures up to 1200℃. Grating dots are etched at 15mm intervals along the fiber axis, for a total of 150 grating dots, forming a fiber grating array.

[0085] (3) Embedding and stress pre-setting The prefabricated fiber Bragg grating array is placed in the groove, aligning each grating point with a preset temperature measurement position. During the embedding process, a pre-tension (0.5-1.0N) is applied to the fiber, placing it in a slightly stretched state within the groove to enhance the interfacial compressive stress during subsequent cooling.

[0086] (4) Filling and fixing A quartz glass powder slurry is used to fill the grooves, and the fiber Bragg grating array is fixed within the grooves. The composition of the quartz glass powder slurry is: quartz glass powder (particle size 1-5μm): 70wt%, deionized water: 25wt%, carboxymethyl cellulose (binder): 5wt%. (To prevent fiber contamination during CVD deposition, a temporary protective layer, such as a peelable adhesive, is applied to the surface of the fiber groove after the fiber is embedded and filled with the quartz glass powder slurry. This layer is removed after all the coating has been deposited.) (5) Stress-induced crystallization and simultaneous sintering The quartz furnace tube embedded with optical fibers is placed in a high-temperature furnace and heat-treated under a nitrogen atmosphere, specifically as follows:

[0087] Key parameter descriptions: The holding temperature of 1100℃ is within the critical window (1000-1200℃) for quartz crystallization, which can induce crystallization without causing excessive crystallization. The heat treatment time of 2 hours is the same as the high-temperature heat treatment time in Example 1, thus merging the processes; Slow cooling (2℃ / min) ensures stable release of stress field and avoids thermal shock cracking.

[0088] (6) Surface finishing The sintered surface is polished to make the fiber grating array flush with the outer wall of the quartz furnace tube.

[0089] After the above-mentioned processing, the fiber / tube wall interface was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that cristobalite crystal phase was precipitated with a grain size of 30-80 nm (average about 55 nm). The distribution area was 10-25 μm deep around the fiber / tube wall interface, with a volume fraction of 5%-12% (local). The distribution characteristics were continuous and diffused along the fiber axis.

[0090] Due to the mechanical interlocking structure formed by the nano-cubic quartz crystals at the interface, the interfacial bonding strength between the optical fiber and the quartz tube wall is significantly improved. Peel tests showed that the pull-out resistance of the optical fiber increased from 2.5N (without crystallization) to 5.8N, an increase of approximately 132%. The nano-cubic quartz crystals formed around the optical fiber act as pinning agents for crack propagation. When a crack propagates from the outer surface of the tube wall to the inner wall, it needs to bypass or pass through the nanocrystals, consuming more fracture energy. Three-point bending tests showed that the local fracture toughness near the optical fiber embedding area (within 5 mm of the fiber) increased from 0.8 MPa·m¹ / ² in the control example to 1.1 MPa·m¹ / ², an increase of approximately 38%. Despite the local crystallization around the optical fiber, the temperature measurement performance of the fiber grating was unaffected. Calibration tests showed that, within the range of room temperature to 1100℃, the temperature sensitivity (approximately 10 pm / ℃) and linearity (R²>0.999) of the fiber grating were consistent with those of the untreated fiber, indicating that stress-induced crystallization did not damage the fiber grating. This embodiment combines optical fiber encapsulation sintering and high-temperature heat treatment of composite coating into a single process, while simultaneously achieving stress-induced crystallization around the optical fiber.

[0091] In traditional techniques, when optical fibers are embedded in quartz tube walls, crystallization is typically avoided, as it is believed that crystallization leads to a decrease in the interfacial strength between the fiber and the tube wall, attenuation of the optical signal, and even fiber breakage. However, when crystallization is precisely controlled at the nanoscale (particle size ≤ 100 nm) and confined to the interfacial micro-region (depth ≤ 30 μm), it not only does not damage the fiber performance but also enhances the interfacial bonding strength by utilizing the pinning effect of the nanocrystals, achieving a technological effect that turns a potential harm into a benefit.

[0092] It should be noted that the stress-induced crystallization in Example 6 and the controllable crystallization pretreatment in Example 4 are two independent implementation schemes, which can be implemented separately or in combination. When implemented in combination, the full-surface crystallization pretreatment is performed first according to Example 4, and then the fiber embedding and local stress-induced crystallization are performed according to Example 6. The two work together to achieve the dual effects of overall toughening and local interface strengthening.

[0093] Example 7: This example is basically the same as Example 1, except that step (5.4) fixing and (5.5) curing / sintering in step (5) are replaced with the following stress annealing treatment steps: (5.5) Stress annealing treatment The quartz furnace tube with the embedded optical fiber is placed in a high-temperature furnace and subjected to stress annealing under a nitrogen atmosphere. The specific process is as follows:

[0094] Stress annealing has the following dual mechanism of action: (a) Precise wavelength tuning During annealing, residual stress in the optical fiber relaxes, causing a permanent drift in the center wavelength of the FBG (fiber Bragg grating). By controlling the annealing temperature (1000-1100℃) and the applied axial stress (0.5-1.5N), wavelength fine-tuning within the range of 1-10nm can be achieved, with a tuning sensitivity of approximately 1.48nm / MPa. This treatment compensates for wavelength deviations during FBG fabrication, ensuring accurate temperature measurement.

[0095] (b) Preset of interfacial compressive stress During the high-temperature annealing process, the interfacial stress between the optical fiber and the quartz furnace tube wall is released and redistributed. During cooling, due to the matching thermal expansion coefficients of the optical fiber and the tube wall material (both are quartz), a stable micro-compressive stress field is formed at the interface. This compressive stress field can counteract the tensile stress generated by temperature cycling during subsequent use, inhibiting the initiation and propagation of interfacial microcracks.

[0096] The mechanism of stress-induced crystallization is as follows: Quartz glass is in a metastable state at high temperatures, and the applied stress field reduces its crystallization activation energy. According to classical nucleation theory, stress can promote atomic rearrangement and accelerate the formation of cristobalite crystal nuclei. In this embodiment, the local stress field generated by the fiber embedding reduces the crystallization activation energy of quartz at the interface by about 20-30%, thereby causing crystallization to occur preferentially in the stress region, while other regions remain amorphous.

[0097] After this technological improvement, the FBG center wavelength accuracy is ±0.1nm (compared to ±0.5nm in the control example, i.e., Example 1), the temperature measurement error is ≤±0.3℃ (compared to ±1.0℃ in the control example), and the fiber interface bonding strength is 6.5N (compared to 4.2N in the control example), representing an improvement of approximately 55%. This embodiment overcomes technical bias. In traditional technologies, residual stress during the fiber optic encapsulation process is considered a detrimental factor that needs to be eliminated, as it can lead to wavelength instability and signal drift. Through extensive experimentation, the inventors have discovered that when stress annealing conditions are precisely controlled, residual stress not only does not impair FBG performance, but can actually be used for precise wavelength tuning and interface compression stress pre-setting, achieving a technical effect that turns disadvantages into advantages.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A quartz furnace tube for semiconductor heat treatment, characterized in that, include: The cylindrical tube is made of quartz glass. A multi-layer gradient composite coating is disposed on the inner wall of the cylindrical tube. The multi-layer gradient composite coating comprises, from the inside out: The transition layer is composed of silicon-oxygen-carbon material. The carbon content of the transition layer increases gradually from the inner surface to the outer surface along the thickness direction, so that the coefficient of thermal expansion increases gradually from the quartz matrix side to the functional layer side. A functional layer is disposed on the outer surface of the transition layer and is composed of a SiC matrix or a Si3N4 matrix and sacrificial nanoparticles dispersed in the matrix. The sacrificial nanoparticles react with the process gas under high-temperature process conditions to generate an oxide protective layer. The surface layer, disposed on the outer surface of the functional layer, is a porous SiO2 layer.

2. The quartz furnace tube for semiconductor heat treatment according to claim 1, characterized in that, The sacrificial nanoparticles are selected from at least one of Si, AlN, and Si3N4, with a particle size of 10-100 nm, and the volume fraction of the sacrificial nanoparticles in the functional layer is 5%-20%.

3. The quartz furnace tube for semiconductor heat treatment according to claim 2, characterized in that, The thickness of the transition layer is 0.5-2 μm, the thickness of the functional layer is 2-5 μm, and the thickness of the surface layer is 0.2-0.5 μm.

4. The quartz furnace tube for semiconductor heat treatment according to claim 3, characterized in that, The coefficient of thermal expansion of the transition layer varies from 0.5 × 10⁻⁶ along its thickness direction. -6 The / K gradient was increased to 3.5 × 10. -6 / K.

5. The quartz furnace tube for semiconductor heat treatment according to claim 1, characterized in that, The porosity of the surface layer is 30%-50%, and the pore size is 5-50 nm.

6. The quartz furnace tube for semiconductor heat treatment according to claim 1, characterized in that, The outer wall surface of the cylindrical tube is provided with a fiber Bragg grating array along the axial direction for real-time monitoring of the axial temperature distribution of the furnace tube.

7. A method for preparing a quartz furnace tube for semiconductor heat treatment as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Transition layer deposition: A silicon-oxygen-carbon transition layer is deposited on the inner wall of the quartz tube by chemical vapor deposition. During the deposition process, the flow ratio of silicon-containing precursor gas to carbon-containing precursor gas is controlled to increase with time, so that the carbon content of the transition layer increases gradually from the inside to the outside along the thickness direction. (2) Functional layer deposition: Chemical vapor deposition is used to introduce silicon-containing precursor gas and carbon-containing precursor gas, or silicon-containing precursor gas and nitrogen-containing precursor gas, and sacrificial nanoparticles are introduced to deposit a SiC or Si3N4 functional layer containing sacrificial nanoparticles on the surface of the transition layer. (3) Surface layer formation: A porous SiO2 surface layer is formed on the surface of the functional layer by using the sol-gel method or plasma-enhanced chemical vapor deposition method; (4) High-temperature heat treatment: High-temperature heat treatment is carried out in an inert atmosphere to form chemical bonds between the layers.

8. The preparation method according to claim 7, characterized in that, The silicon-containing precursor gas in step (1) is silane, and the carbon-containing precursor gas is methane, ethane or ethylene. The deposition temperature is 800-1000℃ and the deposition pressure is 10-100Pa.

9. The preparation method according to claim 7, characterized in that, The sacrificial nanoparticles described in step (2) are introduced into the reaction chamber via aerosol delivery. The carrier gas for the particles is argon or nitrogen. The deposition temperature is 900-1100℃ and the deposition pressure is 50-200Pa.

10. The preparation method according to claim 7, characterized in that, The high-temperature heat treatment in step (4) is performed at a temperature of 1000-1200℃, with a holding time of 1-4 hours, and the atmosphere is argon or nitrogen.

Images