A semiconductor vacuum chamber yttrium oxide coating composition and process of preparation

Abstract

The application discloses a kind of semiconductor vacuum cavity yttrium oxide coating compositions and preparation process thereof, it is related to semiconductor vacuum cavity surface treatment technical field.The composition includes separately packaged transition layer powder, functional layer powder and sealing liquid;Transition layer powder includes Y2O3, Cr2O3, ZrO2 and YOF and / or YF3, functional layer powder includes Y2O3, YOF and / or YF3 and ZrO2 and / or HfO2, sealing liquid includes inorganic yttrium precursor, phosphoric acid or phosphate film-forming component and solvent.The preparation process includes the inner surface of stainless steel vacuum cavity is degreased, electropolished and passivated, laser or electrochemical micro-etching is carried out to coating area to form microtexture, transition layer powder and functional layer powder are sequentially sprayed, and sealing liquid is applied to low-temperature solidification after that.The application is suitable for the inner surface treatment of semiconductor etching, PVD or CVD equipment vacuum cavity.

Description

Technical Field

[0001] This invention relates to the field of semiconductor vacuum cavity surface treatment technology, specifically to a composition and preparation process for a yttrium oxide coating for semiconductor vacuum cavities. Background Technology

[0002] In vacuum processing equipment such as semiconductor etching, PVD, and CVD, the inner surface of the vacuum chamber is exposed to halogen plasmas containing fluorine, chlorine, or bromine, reactive gases, vacuum cycles, thermal cycles, and wet cleaning environments for extended periods. For stainless steel vacuum chambers, the inner wall must meet requirements for vacuum sealing, low metal contamination, low escaping gas, and clean assembly, while also possessing resistance to halogen plasma corrosion and particle release on the process space side.

[0003] Yttrium oxide coatings have been used to protect components of semiconductor plasma equipment. Existing technologies have disclosed the thermal spraying or plasma spraying of yttrium oxide coatings on the surface of cavity components. Gradient spraying structures combining yttrium oxide transition layers and fluorinated yttrium compound working layers have also been disclosed. Furthermore, schemes for sealing pores in yttrium oxide spray coatings to reduce the entry of corrosive media into the interface along pores or microcracks have also been disclosed.

[0004] However, stainless steel vacuum chambers differ from aluminum alloy chambers, ceramic components, or ordinary sandblasted metal components. The inner surface of a stainless steel chamber typically requires electrochemical polishing and passivation to reduce the risk of free iron, processing residues, and metal precipitation. After electrochemical polishing and passivation, the stainless steel surface is relatively smooth and has a passivation film. Direct yttrium oxide thermal spraying may result in insufficient interfacial mechanical bonding and thermal expansion transition conditions. If ordinary sandblasting is used for roughening, it may damage the sealing surface, introduce particulate residues, or reduce the consistency of the high-cleanliness chamber.

[0005] In addition, some existing yttrium oxide coating solutions for enhancing adhesion employ a high proportion of alumina and yttrium oxide composites. While this approach can improve certain coating mechanical properties, for applications requiring low metal contamination, low particle counts, and semiconductor cavity inner walls, it is still necessary to control the introduction of aluminum and its migration risks in halogen plasma environments. Furthermore, some organic sealing agents in existing sealing solutions may also introduce issues related to vacuum venting, residual cleaning, and semiconductor cleanliness compatibility.

[0006] Therefore, there is a need for a composition and preparation process for yttrium oxide coating on the inner surface of a semiconductor stainless steel vacuum chamber, which enables the formation of a controllable microtexture interface, a gradient transition layer, a low-aluminum yttrium oxide functional layer, and a low-temperature sealing structure on the surface of stainless steel after electropolishing and passivation, thereby reducing the risks of interface peeling, particle release, metal contamination, and gas escaping. Summary of the Invention

[0007] The purpose of this invention is to provide a composition and preparation process for yttrium oxide coating of semiconductor vacuum cavities, which solves the technical problems of insufficient interface compatibility between the inner surface of the stainless steel cavity after electropolishing and passivation and the yttrium oxide ceramic coating, the significant impact of ordinary roughening on the sealing surface and cleanliness, and the potential for corrosive media penetration caused by openings and microcracks in the yttrium oxide spray coating.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a composition for yttrium oxide coating of semiconductor vacuum cavities, comprising separately packaged transition layer powder, functional layer powder, and sealing liquid; the transition layer powder comprises, by mass percentage, 50%~75% Y2O3, 12%~22% Cr2O3, 12%~22% ZrO2, and 33%~5% YOF and / or YF; the functional layer powder comprises, by mass percentage, 97.8%~99.0% Y2O3, 0.8%~1.5% YOF and / or YF, and 0.2%~0.7% ZrO2 and / or HfO2; the sealing liquid comprises, by mass percentage, 12%~25% yttrium-containing inorganic precursor, 3%~5% phosphoric acid or phosphate film-forming components, and 70%~85% solvent; the total composition of the transition layer powder, functional layer powder, and sealing liquid is 100%.

[0009] Furthermore, the transition layer powder includes a first transition layer sub-powder and a second transition layer sub-powder; the mass percentage of Y2O3 in the first transition layer sub-powder is 45%~60%, and the mass percentage of Y2O3 in the second transition layer sub-powder is 65%~80%.

[0010] Furthermore, the Al2O3 content in the functional layer powder is controlled to be ≤0.5% by mass as an unavoidable impurity, and the D10 of the functional layer powder is 5μm~20μm, the D50 is 10μm~45μm, and the D90 is 30μm~80μm.

[0011] Furthermore, the yttrium-containing inorganic precursor is selected from one or more of yttrium nitrate, yttrium acetate, and yttrium phosphate sol; the phosphoric acid or phosphate film-forming component is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, and yttrium dihydrogen phosphate; and the solvent is selected from one or more of water, ethanol, and isopropanol. In this invention, the yttrium-containing inorganic precursor refers to a yttrium source capable of forming yttrium-containing inorganic residues or yttrium-containing phosphate networks after low-temperature curing; the phosphoric acid or phosphate film-forming component refers to a component capable of providing a phosphate structure and forming inorganic sealing residues with yttrium-containing species. When the yttrium-containing inorganic precursor is yttrium phosphate sol, the YOP structure in the yttrium phosphate sol simultaneously provides both the yttrium-containing precursor and phosphate film-forming effects.

[0012] Furthermore, both the transition layer powder and the functional layer powder are agglomerated sintered powder or spray-granulated powder, and the particle size of the transition layer powder is 10μm~70μm.

[0013] The present invention also provides a preparation process for the above-mentioned composition for yttrium oxide coating of semiconductor vacuum chamber, comprising the following steps: degreasing, electropolishing and passivating the inner surface of the stainless steel vacuum chamber; forming a microtexture with a depth of 30μm~55μm and a spacing of 100μm~155μm by laser or electrochemical micro-etching of the coating area; sequentially spraying transition layer powder to form a gradient transition layer of 30μm~150μm and spraying functional layer powder to form a yttrium oxide functional layer of 80μm~300μm; applying sealing liquid and curing at 80℃~180℃ for 0.5h~4h.

[0014] Furthermore, the electropolishing process uses an electrolyte containing one or more of phosphoric acid, sulfuric acid, and citric acid, with a current density of 5 A / dm³. 2 ~40A / dm 2 The passivation process is carried out at a temperature of 2 to 30 minutes, and the passivation is performed using a 4% to 20 wt% citric acid aqueous solution or a 10% to 40 wt% nitric acid aqueous solution at a temperature of 20°C to 70°C for 10 to 90 minutes.

[0015] Furthermore, the microtexture includes pits, grooves, or a combination of pits and grooves; the uncoated sealing surface of the stainless steel vacuum cavity is masked before laser or electrochemical micro-etching.

[0016] Furthermore, the spraying is air plasma spraying, with a spraying current of 450A~900A, a spraying voltage of 30V~80V, a spraying distance of 80mm~160mm, a powder feeding rate of 10g / min~60g / min, a main air flow rate of 30L / min~70L / min, and an auxiliary air flow rate of 2L / min~15L / min.

[0017] Furthermore, the sealing liquid is applied by spraying, brushing, or vacuum impregnation; after curing, it is cleaned with ultrapure water and dried at 60℃~150℃, with the resulting yttrium oxide coating facing the process space of semiconductor etching, PVD, or CVD equipment.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention packages the transition layer powder, functional layer powder, and sealing liquid as a complete set for sequential use, allowing interface transition, plasma protection, and sealing treatment to correspond to different material layers. Microtextures are formed through laser or electrochemical micro-etching, and a Cr2O3-ZrO2-YOF / YF3 transition system is applied on top, improving the interfacial compatibility between the electropolished and passivated stainless steel surface and the ceramic coating. The low-Al2O3 functional layer powder reduces the semiconductor cleanliness compatibility risks associated with high-alumina systems. The sealing liquid, composed of yttrium inorganic precursors and phosphoric acid or phosphate film-forming components, improves the material compatibility of sealing residues with the yttrium oxide functional layer and reduces the risk of organic sealing residues. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the preparation process of the composition for the yttrium oxide coating of the semiconductor vacuum cavity of the present invention.

[0021] Figure 2 This is a schematic cross-sectional view of the oxide coating structure of the semiconductor vacuum cavity of the present invention.

[0022] Figure 3 This is a schematic diagram illustrating the principle of the sealing liquid entering the openings and microcracks of the yttrium oxide functional layer according to the present invention. Detailed Implementation

[0023] 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, and 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.

[0024] Unless otherwise stated, all mass percentages below are based on the total mass of the corresponding powder or liquid components. The semiconductor vacuum chamber can be a stainless steel vacuum chamber, chamber liner, baffle, shield, or other metal vacuum component exposed to the process space in etching equipment, PVD equipment, or CVD equipment. The stainless steel can be 304L, 316L, or 316LN stainless steel.

[0025] like Figure 1As shown, the preparation process of this invention proceeds in the order of surface cleaning, interface reconstruction, layered spraying, and pore sealing curing of a stainless steel vacuum cavity or simulated sample. This process does not involve directly spraying the yttrium oxide coating onto the stainless steel surface. Instead, after degreasing, cleaning, ultrapure water rinsing, electropolishing, and passivation, the uncoated sealing surface is masked, and laser micro-etching or electrochemical micro-etching is performed only in the coated area. This preserves the integrity of both the sealing surface and the clean surface, while also creating an interface morphology suitable for ceramic coating bonding in the coated area. Subsequently, a transition layer and a functional layer are sprayed sequentially, followed by the application of a sealing liquid, low-temperature curing, cleaning, and drying. This allows interface bonding, plasma corrosion resistance, and pore sealing to be synergistically achieved within the same process chain.

[0026] like Figure 2 As shown, the resulting coating structure, from the stainless steel substrate towards the process space, sequentially comprises a microtextured layer, a gradient transition layer, a yttrium oxide functional layer, and a sealing layer. The microtextured layer enhances the mechanical adhesion between the stainless steel substrate and the coating layer; the gradient transition layer, located between the stainless steel substrate and the yttrium oxide functional layer, mitigates the thermal expansion differences and interfacial stress concentration between the metal substrate and the ceramic functional layer; the yttrium oxide functional layer faces the semiconductor process space and withstands the corrosion from halogen plasmas containing fluorine and chlorine, as well as reactive atmospheres; the sealing layer, located on the outermost side, seals the surface openings and microcracks of the yttrium oxide functional layer. This layered structure embodies a continuous technical path of substrate cleansing, interface strengthening, gradient transition, functional protection, and surface sealing.

[0027] like Figure 3 As shown, the sealing liquid enters the open pores and microcracks on the surface of the yttrium oxide functional layer from the process space side, and forms sealing residue and a sealing layer after low-temperature curing. If the open pores and microcracks are not sealed, they can easily become channels for halogen plasma, cleaning fluid, or corrosive media to penetrate into the coating interior and interface. This invention fills the above-mentioned defects with an inorganic sealing system compatible with the yttrium oxide functional layer, which helps to reduce the interconnected pores in the coating, slow down the propagation of corrosive media along pores and cracks, and reduce particle release caused by pore edge peeling or coarsening.

[0028] comprehensive Figures 1 to 3 It is understood that the technical effect of this invention does not originate from a single yttrium oxide spray coating, a single surface roughening, or a single sealing treatment, but rather from the synergistic effect between the clean stainless steel surface after electropolishing and passivation, the controllable microtexture of the coating area, the gradient transition layer, the low-aluminum yttrium oxide functional layer, and the yttrium-containing inorganic sealing structure. This synergistic structure can simultaneously achieve the requirements of low metal contamination, low particle release, low gas emission, resistance to halogen plasma corrosion, and integrity of the sealing surface required by semiconductor vacuum cavities, thus distinguishing it from conventional solutions such as thermal spraying of yttrium oxide layers onto ordinary metal substrates or direct spraying of ceramic layers after random sandblasting.

[0029] Example 1: In this embodiment, a 316L stainless steel simulated cavity sample was selected, with sample dimensions of 100mm×50mm×5mm. The sample was cleaned in an alkaline degreasing solution at 50℃ for 10 minutes, rinsed three times with ultrapure water with a resistivity of not less than 15MΩ·cm, and dried at 80℃ for 30 minutes. Electropolishing was performed on the inner surface of the sample: the electrolyte consisted of phosphoric acid and sulfuric acid, and the current density was 20 A / dm³. 2 The processing time was 10 min, and the electrolyte temperature was 45℃. After electropolishing, the sample was rinsed three times with ultrapure water. Then, it was passivated with 10 wt% citric acid aqueous solution at a passivation temperature of 50℃ for 30 min. After passivation, it was rinsed with ultrapure water and dried at 80℃ for 30 min. The uncoated sealing surface is shielded using a metal shielding fixture: the coated area is laser micro-etched to form pit-type micro-textures, with the pit depth set at 30μm and the pit spacing at 120μm; after laser micro-etching, the shielding fixture is removed, and the area is cleaned and dried with ultrapure water; Preparation of transition layer powder: Weigh out 60% Y2O3, 18% Cr2O3, 18% ZrO2 and 4% YOF by mass percentage, add ethanol for dispersion, wet mix and spray granulation, dry and sieve to obtain transition layer powder with a particle size of 10μm~70μm. Preparation of functional layer powder: 98.5% Y2O3, 1.0% YOF, and 0.5% ZrO2 were weighed by mass percentage, dispersed, spray-granulated, dried, and sieved to obtain functional layer powder, with the Al2O3 content controlled to be ≤0.5%; Preparation of sealing solution: Weigh 15% yttrium nitrate, 3% ammonium dihydrogen phosphate, 62% water and 20% ethanol by mass percentage, stir at room temperature for 40 min, and filter to obtain sealing solution; Air plasma spraying was used to spray transition layer powder onto the coating area. The spraying current was 600A, the spraying voltage was 60V, the spraying distance was 120mm, the powder feed rate was 35g / min, the main gas flow rate was 45L / min, and the auxiliary gas flow rate was 8L / min, forming a gradient transition layer. Subsequently, functional layer powder was sprayed onto the gradient transition layer. The spraying current was 620A, the spraying voltage was 62V, the spraying distance was 120mm, the powder feed rate was 30g / min, the main gas flow rate was 45L / min, and the auxiliary gas flow rate was 8L / min, forming a yttrium oxide functional layer. The sealing liquid was brushed onto the surface of the yttrium oxide functional layer, left to stand for 10 minutes, and then cured at 150°C for 2 hours. After curing, it was washed with ultrapure water and dried at 100°C for 1 hour to obtain the sample of Example 1.

[0030] Example 2: In this embodiment, a 304L stainless steel simulated cavity sample with dimensions of 100mm × 50mm × 5mm was selected. The sample was degreased, cleaned, rinsed with ultrapure water, and dried. Electropolishing was performed using an electrolyte containing phosphoric acid, sulfuric acid, and citric acid, with a current density of 15A / dm³. 2 The processing time was 15 minutes, and the electrolyte temperature was 40°C. After electropolishing, the sample was rinsed with ultrapure water. Passivation was performed using a 20% nitric acid aqueous solution at a temperature of 30°C for 40 minutes. After passivation, the sample was rinsed with ultrapure water and dried. The uncoated sealing surface is masked with an acid and alkali resistant masking film; the coated area is electrochemically micro-etched to form a groove-type microtexture, with the groove depth set at 40μm and the groove spacing at 150μm; after micro-etching is completed, the masking film is removed, and the area is cleaned and dried. Preparation of the first transition layer powder: 50% Y2O3, 25% Cr2O3, 22% ZrO2 and 33% YF were weighed by mass percentage, and the powder was obtained by wet mixing, spray granulation, drying and sieving. Preparation of the second transition layer powder: Y2O3 75%, Cr2O3 10%, ZrO2 12% and YF 33% were weighed by mass percentage, and the powder was obtained by wet mixing, spray granulation, drying and sieving. Preparation of functional layer powder: 97.8% Y2O3, 1.5% YF3, and 0.7% HfO2 were weighed by mass percentage, dispersed, granulated, dried, and sieved to obtain functional layer powder, with the Al2O3 content controlled to be ≤0.5%; Preparation of sealing solution: Weigh 12% yttrium acetate, 3% phosphoric acid, 70% water and 15% isopropanol by mass percentage, stir and filter for later use; Air plasma spraying is used to first spray the first transition layer powder, and then spray the second transition layer powder to form a gradient transition layer with increasing Y2O3 content from the stainless steel side to the outside; the spraying current is 580A, the spraying voltage is 58V, the spraying distance is 110mm, the powder feed rate is 32g / min, the main gas flow rate is 45L / min, and the auxiliary gas flow rate is 8L / min. Functional layer powder was sprayed onto the gradient transition layer with a spraying current of 620A, a spraying voltage of 62V, a spraying distance of 120mm, a powder feed rate of 30g / min, a main gas flow rate of 45L / min, and an auxiliary gas flow rate of 8L / min. Subsequently, sealing liquid was applied by vacuum impregnation at a pressure of -80kPa for 5min, followed by curing at 140℃ for 2h. After curing, the sample was washed with ultrapure water and dried at 100℃ for 1h to obtain the sample of Example 2.

[0031] Example 3: In this embodiment, a 316LN stainless steel simulated cavity sample with dimensions of 100mm × 50mm × 5mm was selected. The sample was cleaned with an alkaline degreasing solution at 50℃ for 10 minutes, rinsed with ultrapure water, and dried at 80℃ before electropolishing. The electrolyte contained phosphoric acid and citric acid, and the current density was 25A / dm³. 2 The treatment time was 8 minutes, and the electrolyte temperature was 45°C. Subsequently, the sample was passivated with 8% citric acid aqueous solution at 60°C for 30 minutes, then washed with ultrapure water and dried. The uncoated sealing surface is masked using a metal masking fixture: the coated area is laser micro-etched to form a microtexture of grooves and pits, with the microtexture depth set at 50μm and the microtexture spacing at 100μm; after the microtexture is completed, the masking fixture is removed, and the area is cleaned and dried. Preparation of transition layer powder: Weigh out 68% Y2O3, 12% Cr2O3, 16% ZrO2 and 4% YOF by mass percentage, mix them by wet method, spray granulate, dry and sieve; Preparation of functional layer powder: Weigh 99.0% Y2O3, 0.8% YOF and 0.2% ZrO2 by mass percentage, disperse, granulate, dry and sieve to obtain functional layer powder, and control the Al2O3 content ≤0.5%; Preparation of sealing solution: Weigh 25% yttrium phosphate sol, 60% water and 15% ethanol by mass percentage, stir at room temperature for 30 min, filter and set aside; A gradient transition layer is formed using air plasma spraying with a spraying current of 600A, a spraying voltage of 60V, a spraying distance of 120mm, a powder feed rate of 35g / min, a main gas flow rate of 45L / min, and an auxiliary gas flow rate of 8L / min. Subsequently, a yttrium oxide functional layer is formed with a spraying current of 630A, a spraying voltage of 62V, a spraying distance of 120mm, a powder feed rate of 30g / min, a main gas flow rate of 45L / min, and an auxiliary gas flow rate of 8L / min. The sealing liquid was sprayed onto the surface of the yttrium oxide functional layer. After spraying, it was left to stand for 10 minutes and then cured at 120°C for 3 hours. After curing, it was cleaned with ultrapure water and dried at 90°C for 2 hours to obtain the sample of Example 3.

[0032] Comparative Example 1: The steps of substrate, electropolishing, passivation, microtexturing treatment, functional layer powder, functional layer spraying, sealing liquid, curing, cleaning and drying in this comparative example are the same as those in Example 1. The difference is that no transition layer powder is sprayed, and the functional layer powder is directly sprayed on the stainless steel coating area after microtexturing treatment to form a yttrium oxide functional layer.

[0033] Comparative Example 2: The steps of substrate, electropolishing, passivation, transition layer powder, functional layer powder, sealing liquid, spraying, curing, cleaning and drying in this comparative example are the same as those in Example 1. The difference is that the coated area is not subjected to laser micro-etching or electrochemical micro-etching, but is sandblasted with alumina particles to form a random rough surface.

[0034] Comparative Example 3: The steps for substrate, electropolishing, passivation, microtexturing, transition layer powder, sealing liquid, spraying, curing, cleaning and drying in this comparative example are the same as those in Example 1. The difference is that the functional layer powder is replaced with Y2O3 / Al2O3 composite powder, wherein the mass percentage of Al2O3 is 20% and the remainder is Y2O3.

[0035] Comparative Example 4: The steps for substrate, electropolishing, passivation, microtexturing, transition layer spraying, and functional layer spraying in this comparative example are the same as in Example 1. The difference is that no sealing treatment is performed after spraying; instead, ultrapure water cleaning and drying are carried out directly.

[0036] Comparative Example 5: The steps for substrate, microtexture, transition layer powder, functional layer powder, sealing liquid, spraying, curing, cleaning and drying in this comparative example are the same as those in Example 1. The difference is that electropolishing and passivation are not performed. Instead, degreasing and cleaning, rinsing with ultrapure water and drying are performed before microtexturing treatment.

[0037] Test example: Powder particle size was measured using the ISO 13320:2020 laser diffraction method. Ethanol was used as the dispersion medium, and the samples were ultrasonically dispersed for 3 minutes. Each powder sample was tested three times, and the average value was taken. This test was used to demonstrate that the transition layer powder particle size falls within the range of 10 μm to 70 μm, and that the functional layer powders D10, D50, and D90 fall within the specified ranges, thus demonstrating that the powder possesses the foundation for stable powder feeding and air plasma spraying preparation.

[0038] The viscosity of the sealing solution was tested using a rotational viscometer at 25°C under the following conditions: rotor #2, 60 rpm. The solid content of the sealing solution was determined by drying at 105°C to constant weight. The stability of the sealing solution was assessed by visual observation after standing at room temperature for 24 hours. This test demonstrates that the sealing solution, composed of yttrium inorganic precursors, phosphoric acid or phosphate film-forming components, and solvent, can be stored separately in a homogeneous liquid form and is suitable for brushing, spraying, or vacuum impregnation.

[0039] The microtexture geometry was measured using a white light interferometer, with the test aperture conforming to ISO 25178-2:2021. A 1mm × 1mm test area was selected for each sample, and five measurements were taken at each sample, with the average value recorded. This test demonstrates that laser micro-etching or electrochemical micro-etching can form pits, grooves, or composite microtextures with a depth of 30μm–55μm and a spacing of 100μm–155μm. It also serves to distinguish the regular microtextures of this invention from the random coarsening morphology formed by conventional sandblasting.

[0040] The condition of the uncoated sealing surface was measured using a profilometer, with five measurements taken at each sample and the average value recorded. Simultaneously, the masking boundary was observed using a 50x microscope. This test demonstrates that the uncoated sealing surface is protected by masking during microtexturing and spraying processes, and that it does not exhibit significant roughening, deposition, or scratches due to microtexturing reconstruction or spraying in the coated area.

[0041] The coating thickness was measured according to GB / T 11374-2012. Five locations were selected on the cross-section of each sample for measurement, and the average value was taken. This test was used to demonstrate that the gradient transition layer thickness is 30μm~150μm and the yttrium oxide functional layer thickness is 80μm~300μm, thus indicating that the defined layered structure can be achieved by the process of this invention.

[0042] Porosity was determined using the GB / Z 45463-2025 standard for testing the porosity of thermal spray coatings. Statistical analysis was performed using the cross-sectional image method, with at least five fields of view for each sample and the average value taken. This test was used to demonstrate that the sealing liquid, after entering the open pores and microcracks of the yttrium oxide functional layer, can reduce the observable porosity of the sealed coating, and to compare the differences between sealed and unsealed samples.

[0043] Tensile bond strength was tested using ASTM C633-24, with at least five samples per group and the average value taken. This test was used to demonstrate that the combination of electropolishing passivation, controlled microtexturing, and the Cr2O3-ZrO2-YOF / YF3 gradient transition layer helps improve the interfacial bonding reliability between the yttrium oxide coating and the stainless steel substrate, and to compare the examples with those without a transition layer, conventional sandblasting, and those omitting electropolishing passivation.

[0044] Thermal cycling tests were conducted under custom fixed conditions: samples were cycled between 25°C and 200°C at a heating rate of 10°C / min, held at 200°C for 30 min, cooled to 25°C, and held for 30 min, for a total of 100 cycles. After cycling, the appearance was observed visually and under a 50x microscope. This test was used to demonstrate the contribution of the gradient transition layer and sealing structure to the coating integrity and interface stability after thermal cycling.

[0045] Halogen plasma exposure testing was conducted under customized fixed conditions: a CF4 / O2 volumetric flow rate ratio of 90:10, a chamber pressure of 20 Pa, an RF power of 800 W, a stage temperature of 80 °C, and an exposure time of 120 min. Samples were weighed before and after exposure, and the etching depth was measured. The etching rate was calculated, and the presence of peeling, roughening, or particle adhesion on the surface was observed. This test was used to demonstrate the adaptability of the low-Al2O3 yttrium oxide functional layer and sealing structure to the halogen plasma environment.

[0046] Surface particle cleanliness was evaluated using ISO 14644-9:2022. During testing, ultrapure water was used to rinse and extract samples per unit area. A liquid particle counter was used to record particles ≥0.3 μm, and the results were normalized by area. This test was used to demonstrate that controllable microtexturing, low-Al functional layers, and pore sealing treatment can reduce the risk of surface particle release.

[0047] Metal element extraction tests were conducted under customized fixed conditions: the sample was immersed in ultrapure water at 85℃ for 24 hours, and the sample area to water volume ratio was 1 cm². 2 / 10mL, the content of Fe, Cr, Ni and Al elements was determined by ICP-MS and normalized by area. This test was used to demonstrate that electropolishing passivation can reduce the leaching of relevant metal elements from the stainless steel matrix, and that the low Al2O3 functional layer can reduce the risk of aluminum leaching.

[0048] Vacuum venting tests were conducted according to ASTM E595-15 (2021), with test conditions of 125°C and pressure below 7 × 10⁻⁶. - 3 The test was conducted at 24 hours at 1000 Pa, recording the total mass loss (TML) and the collected volatile condensable matter (CVCM). This test was used to demonstrate that the yttrium phosphate sealing solution, after curing, cleaning, and drying, has a controllable vacuum venting level and to balance the sealing protection effect with the risk of vacuum residue.

[0049] Helium leak testing was performed according to GB / T 15823-2009 or ISO 20485:2017, using a helium mass spectrometry leak detection jet method, and the maximum leak detection value was recorded. This test was used to demonstrate that the coating preparation process of this invention does not damage the sealing integrity of the stainless steel vacuum chamber or simulated chamber component, and to compare the effects of masking microtexture treatment and ordinary sandblasting roughening on the sealing margin.

[0050] The specific test results are shown in the table below: Analysis of experimental results: In Examples 1 to 3, the functional layer powders D10, D50, and D90 all fall within the defined range, and the transition layer powder particle size also falls within the range of 10 μm to 70 μm, indicating that powders suitable for air plasma spraying can be obtained through spray granulation, drying, and sieving. The functional layer powder D50 in Example 1 is 27.8 μm, in Example 2 it is 29.1 μm, and in Example 3 it is 24.6 μm, all within the range of 10 μm to 45 μm, which supports the defined particle size of the functional layer powders. Although the functional powder particle size in Comparative Example 3 is also suitable for spraying, its functional layer Al2O3 content is 20.0%, which is significantly different from the low Al2O3 functional layer system of this invention.

[0051] The viscosity of the sealing liquid in Examples 1 to 3 was 8.5 mPa·s, 6.9 mPa·s, and 12.6 mPa·s, respectively. All three showed no visible layering, sedimentation, or gelation after 24 hours at room temperature, indicating that the yttrium nitrate, yttrium acetate, and yttrium phosphate sol systems can all be used as separately packaged sealing liquids. In Example 2, the lower viscosity of the sealing liquid during vacuum impregnation was more conducive to the entry of the sealing liquid into the pores and microcracks of the yttrium oxide functional layer. Example 3 had a higher solids content, making it more suitable for the formation of more inorganic residues after spraying. Comparative Example 4 did not use a sealing liquid; therefore, its sealing liquid viscosity, solids content, and stability parameters are not applicable.

[0052] Example 1 formed a pit-type microtexture with a depth of 31.8 μm and a spacing of 121 μm; Example 2 formed a groove-type microtexture with a depth of 42.5 μm and a spacing of 151 μm; Example 3 formed a composite microtexture with a depth of 50.9 μm and an average spacing of 102 μm, all falling within the range of depth 30 μm to 55 μm and spacing 100 μm to 155 μm. Comparative Example 2 only formed a random sandblasting morphology, without regular pit or groove spacing, indicating that the microtexture reconstruction of the present invention is different from ordinary sandblasting coarsening.

[0053] The uncoated sealing surfaces Ra in Examples 1 and 2 were 0.18 μm and 0.20 μm, respectively, with no visible spray coating deposits or scratches. In Comparative Example 2, the uncoated sealing surface Ra was 0.68 μm, and traces of sandblasting effects and particle residue were visible. This comparison demonstrates that masking the uncoated sealing surface and performing laser or electrochemical micro-etching only in the coated area helps maintain the sealing surface condition and reduces the risk of damage to the sealing surface caused by ordinary sandblasting.

[0054] The gradient transition layer thicknesses in Examples 1 to 3 were 79.6 μm, 96.5 μm, and 88.3 μm, respectively, and the yttrium oxide functional layer thicknesses were 184.2 μm, 191.4 μm, and 176.8 μm, respectively, all falling within the defined range of 30 μm to 150 μm for the gradient transition layer and 80 μm to 300 μm for the yttrium oxide functional layer. These results demonstrate that the air plasma spraying window of this invention can fabricate multilayer structures that meet the layer thickness requirements. Comparative Example 1 had a gradient transition layer thickness of 0 μm, serving as a control without a transition layer.

[0055] After sealing, the porosities of Examples 1 to 3 were 1.1%, 0.9%, and 0.8%, respectively, while the porosity of Comparative Example 4 without sealing was 2.7%. These results indicate that after the sealing liquid enters the open pores and microcracks of the yttrium oxide functional layer, it can reduce the observable porosity, thereby reducing the risk of halogen plasma or cleaning liquid penetrating into the coating along the open pores.

[0056] The tensile bond strengths of Examples 1 to 3 were 18.4 MPa, 20.1 MPa, and 19.2 MPa, respectively, all higher than those of Comparative Example 1 (12.8 MPa), Comparative Example 2 (14.6 MPa), and Comparative Example 5 (15.1 MPa). These results indicate that simply spraying the yttrium oxide functional layer, using ordinary sandblasting instead of controllable microtexture, and omitting electropolishing passivation cannot achieve the bond strength level of the complete combination scheme.

[0057] Examples 1 to 3 showed no visible peeling after 100 thermal cycles at temperatures ranging from 25°C to 200°C. Comparative Example 1 showed edge peeling and interfacial crack propagation, while Comparative Example 4 showed an increase in the number of surface microcracks compared to Example 1. These results indicate that the gradient transition layer helps improve interfacial thermal cycling stability, and the sealing structure helps suppress the continued propagation of surface microcracks.

[0058] Under CF4 / O2 halogen plasma exposure conditions, the etching rates of Examples 1 to 3 were 19.4 nm / min, 17.8 nm / min, and 18.6 nm / min, respectively, all lower than the 26.4 nm / min of Comparative Example 3 and the 32.8 nm / min of Comparative Example 4. This result indicates that the low-Al2O3 yttrium oxide functional layer and the yttrium phosphate-containing sealing structure can reduce the risk of surface roughening and pore edge erosion. Comparative Example 4 exhibited the highest etching rate, suggesting that unsealed openings and microcracks easily become plasma erosion channels.

[0059] The release of ≥0.3μm surface particles in Examples 1 to 3 was 0.34 particles / cm², respectively. 2 0.28 particles / cm 2 and 0.31 grains / cm 2 This is lower than the 1.42 particles / cm of Comparative Example 2. 2Comparative Example 3: 0.86 particles / cm 2 Compared to 1.18 particles / cm in Comparative Example 4 2 These results demonstrate that controllable microtexture, low-Al functional layers, and pore-sealing structures work together to reduce the risk of particle release.

[0060] The metal element leaching results showed that the Al leaching amounts in Examples 1 to 3 were 0.08 ng / cm³, respectively. 2 0.07ng / cm 2 and 0.06 ng / cm 2 It is significantly lower than the 4.50 ng / cm of the comparative example 3 with a high Al2O3 functional layer. 2 The Fe, Cr, and Ni extraction amounts in Examples 1 to 3 were also lower than those in Comparative Example 5, which omitted electropolishing and passivation. This result indicates that a low Al₂O₃ functional layer can reduce the risk of aluminum extraction, and that electropolishing and passivation steps can reduce the risk of precipitation of related elements from the stainless steel matrix.

[0061] Vacuum venting results showed that the TML (Total Molecular Weight) of Examples 1 to 3 was 0.19%, 0.17%, and 0.21%, respectively, and the CVCM (Chemical Vapor Flow Rate) was 0.006%, 0.005%, and 0.007%, respectively. The TML and CVCM of the unsealed sample in Comparative Example 4 were slightly lower, but its porosity, particle release, and halogen plasma exposure were poorer. These results indicate that yttrium phosphate sealing introduces a small amount of solidification residue, but the overall venting level is controllable, and improvements in porosity, etching resistance, and low particle count can be achieved in return.

[0062] The helium leak detection results showed that the leak detection rates for Examples 1 to 3 were 2.0 × 10⁻⁶, respectively. -12 Pa·m 3 / s, 1.8×10 -12 Pa·m 3 / s and 2.3×10 -12 Pa·m 3 / s, Comparative Example 2 is 8.5×10 -12 Pa·m 3 / s. This result shows that the present invention uses shielding to protect the sealing surface and reconstructs the microtexture of the coating area, which does not damage the sealing integrity of the vacuum cavity; ordinary sandblasting roughening is more likely to reduce the sealing allowance.

[0063] In summary, the technical effect of this invention does not come from a single yttrium oxide spray coating, a single pore sealing, or ordinary roughening, but from a combination of transition layer powder, functional layer powder, yttrium phosphate sealing liquid, electropolishing passivation, controllable microtexture, layered spraying, and low-temperature curing.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0065] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composition for yttrium oxide coating of a semiconductor vacuum cavity, characterized in that, The product comprises separately packaged transition layer powder, functional layer powder, and sealing liquid. The transition layer powder, by mass percentage, includes 50%–75% Y₂O₃, 12%–22% Cr₂O₃, 12%–22% ZrO₂, and 3%–5% YOF and / or YF₃. The functional layer powder, by mass percentage, includes 97.8%–99.0% Y₂O₃, 0.8%–1.5% YOF and / or YF₃, and 0.2%–0.7% ZrO₂ and / or HfO₂, with Al₂O₃ being controlled to have a mass percentage ≤0.5% as an unavoidable impurity. The sealing liquid, by mass percentage, includes 12%–25% yttrium-containing inorganic precursor, 3%–5% phosphoric acid or phosphate film-forming components, and 70%–85% solvent. The total composition of the transition layer powder, functional layer powder, and sealing liquid is 100%.

2. The composition for yttrium oxide coating of a semiconductor vacuum cavity according to claim 1, characterized in that, The transition layer powder includes a first transition layer sub-powder and a second transition layer sub-powder; the mass percentage of Y2O3 in the first transition layer sub-powder is 45%~60%, and the mass percentage of Y2O3 in the second transition layer powder is 65%~80%.

3. The composition for yttrium oxide coating of a semiconductor vacuum cavity according to claim 1, characterized in that, The functional layer powder has a D10 of 5μm to 20μm, a D50 of 10μm to 45μm, and a D90 of 30μm to 80μm.

4. The composition for yttrium oxide coating of a semiconductor vacuum cavity according to claim 1, characterized in that, The yttrium-containing inorganic precursor is selected from one or more of yttrium nitrate, yttrium acetate, and yttrium phosphate sol; the phosphoric acid or phosphate film-forming component is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, and yttrium dihydrogen phosphate; and the solvent is selected from one or more of water, ethanol, and isopropanol.

5. The composition for yttrium oxide coating of a semiconductor vacuum cavity according to claim 1, characterized in that, Both the transition layer powder and the functional layer powder are agglomerated sintered powder or spray granulated powder, and the particle size of the transition layer powder is 10μm~70μm.

6. A process for preparing a composition for a yttrium oxide coating of a semiconductor vacuum cavity, characterized in that, The composition according to any one of claims 1 to 5 comprises the following steps: degreasing, electropolishing and passivating the inner surface of the stainless steel vacuum chamber; forming a microtexture with a depth of 30 μm to 55 μm and a spacing of 100 μm to 155 μm by laser or electrochemical micro-etching of the coating area; sequentially spraying transition layer powder to form a gradient transition layer of 30 μm to 150 μm and spraying functional layer powder to form a yttrium oxide functional layer of 80 μm to 300 μm; applying a sealing liquid and curing at 80℃ to 180℃ for 0.5 h to 4 h.

7. The preparation process of the composition for a yttrium oxide coating of a semiconductor vacuum cavity according to claim 6, characterized in that, The electropolishing process uses an electrolyte containing one or more of phosphoric acid, sulfuric acid, and citric acid, with a current density of 5 A / dm³. 2 ~40A / dm 2 The passivation process is carried out at a temperature of 2 to 30 minutes, and the passivation is performed using a 4% to 20 wt% citric acid aqueous solution or a 10% to 40 wt% nitric acid aqueous solution at a temperature of 20°C to 70°C for 10 to 90 minutes.

8. The preparation process of a composition for a yttrium oxide coating of a semiconductor vacuum cavity according to claim 6, characterized in that, The microtexture includes pits, grooves, or a combination of pits and grooves; the uncoated sealing surface of the stainless steel vacuum cavity is masked before laser or electrochemical micro-etching.

9. The preparation process of a composition for a yttrium oxide coating of a semiconductor vacuum cavity according to claim 6, characterized in that, The spraying is air plasma spraying, with a spraying current of 450A~900A, a spraying voltage of 30V~80V, a spraying distance of 80mm~160mm, a powder feeding rate of 10g / min~60g / min, a main air flow rate of 30L / min~70L / min, and an auxiliary air flow rate of 2L / min~15L / min.

10. The preparation process of a composition for a yttrium oxide coating of a semiconductor vacuum cavity according to claim 6, characterized in that, The sealing liquid is applied by spraying, brushing, or vacuum impregnation; after curing, it is cleaned with ultrapure water and dried at 60℃~150℃.

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