Plasma-etching-resistant nano-structure composite ceramic coating and preparation method thereof

Abstract

The invention discloses a nano-structure composite ceramic coating resistant to plasma etching and a preparation method thereof, and belongs to the technical field of surface protection in the semiconductor device manufacturing process, the composite ceramic coating comprises a priming layer and a surface protection layer which are sequentially deposited on a substrate by adopting a vacuum cold spraying method, the priming layer is made of oxide ceramic, and the surface protection layer is made of silicon oxide. The surface protection layer is made of high-stability rare earth ceramic, the thickness of the bottom layer is 0.2-20 microns, the grain size of the bottom layer is 10-200 nm, the thickness of the surface protection layer is 1-10 microns, and the grain size of the surface protection layer is 10-50 nm. According to the method, the oxide ceramic coating is manufactured on the surface of the substrate through a vacuum cold spraying method to serve as a base coat and then is subjected to heat treatment, so that it is guaranteed that the coating has high binding force, the subsequent coating is prevented from falling off, and when high-stability rare earth ceramic is manufactured, powder with the small powder particle size is selected for manufacturing; therefore, the coating is ensured to have certain etching resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of surface protection in the process of manufacturing semiconductor devices, and in particular to a plasma etching resistant nanostructured composite ceramic coating and a preparation method thereof. Background Art

[0002] As semiconductor manufacturing processes continue to advance toward higher precision and smaller feature sizes, plasma etching technology, as a core method for pattern transfer, is experiencing a shift toward higher energy density, higher frequency, and more reactive processes. In advanced processes (e.g., 5nm and below), to meet stringent requirements for etch selectivity, pattern fidelity, and device cleanliness, the protective performance of internal components within the etching chamber has become a key factor impacting equipment performance and device yield. In particular, under fluorine-containing etching gases such as CF4 and CHF3, plasma can cause severe corrosion and sputtering on equipment surface materials, easily leading to erosion and degradation of critical components such as the chamber lining, and subsequently causing microparticle contamination. This contamination can deposit on the wafer surface, reducing yield. Furthermore, frequent replacement and maintenance of equipment components can cause production interruptions and increase costs.

[0003] To improve equipment life and process stability in plasma etching environments, thermal spraying techniques (such as atmospheric plasma spraying) are widely used to deposit ceramic protective layers of controlled thickness on equipment components. Currently, thermal spray coatings based on Y2O3 or Al2O3 offer some degree of effective protection against high-temperature and highly corrosive plasmas, leading to their widespread application in large-scale semiconductor etching equipment (e.g., 8 inches and larger). However, ceramic coatings produced using traditional thermal spraying processes often exhibit defects such as micropores and cracks. Under long-term high-power plasma bombardment, these defects can easily induce particle flaking, leading to wafer surface contamination and process instability, impacting chip yield. To enhance etch protection, coating thicknesses often need to be increased to hundreds of microns, significantly increasing coating preparation costs and limiting their further application in higher-end processes.

[0004] In recent years, increasing research has focused on constructing dense nanostructured coatings to enhance corrosion and impact resistance in high-energy plasma environments. These dense structures not only help shield the erosion paths of high-energy ions in the plasma but also significantly reduce the risk of particle generation and interfacial crack propagation. Furthermore, nanoscale structural manipulation can effectively optimize the internal stress distribution and interfacial bonding strength of the coating, induce uniform etching of the coating surface, and reduce the generation of particulate contaminants, thereby improving reliability while maintaining thickness control and insulating properties.

[0005] Therefore, there is an urgent need to develop a composite ceramic nano-coating system with high density, excellent electrical insulation, and strong plasma corrosion resistance, and to match it with a new preparation process suitable for low-temperature, high-coverage deposition, so as to meet the higher requirements of advanced semiconductor manufacturing equipment for the protective performance of structural parts and improve the operating stability and process yield of the entire machine. Summary of the Invention

[0006] In response to the above problems, the purpose of the present invention is to provide a plasma-etching resistant nanostructured composite ceramic coating and a preparation method, aiming to solve the problems of poor etching resistance, insufficient coating density, weak adhesion to the substrate, poor thermal stability, and high cost due to thick coatings in existing plasma protective coatings during semiconductor manufacturing. The present invention adopts a vacuum cold spraying method to prepare a composite ceramic coating having a base layer, an intermediate transition layer, and a surface protective layer on a substrate. By controlling the process parameters and coating thickness of each coating, a protective coating with good plasma etching resistance and a thickness of no more than 50μm is prepared. The coating has a reasonable structural design, a stable material system, and a controllable preparation process. It can provide excellent protection performance in high-energy environments such as plasma etching, extend device life, and improve process windows and integrated reliability.

[0007] To achieve the above-mentioned purpose, the present invention first provides a plasma-etching-resistant nanostructured composite ceramic coating, comprising a base layer and a surface protective layer deposited sequentially on a substrate by a vacuum cold spraying method, wherein the base layer material is an oxide ceramic, and the surface protective layer material is a high-stability rare earth ceramic. The base layer has a thickness of 0.2 to 20 μm, a grain size of 10 to 200 nm, and a coating porosity of <2%. The surface protective layer has a thickness of 1 to 10 μm, a grain size of 10 to 50 nm, and a coating porosity of <1%.

[0008] In one embodiment of the present invention, an intermediate transition layer is further provided between the base layer and the surface protective layer, and the intermediate transition layer is a composite of oxide ceramics and high-stability rare earth ceramics; the intermediate transition layer has a thickness of 0.2 to 20 μm, a grain size range of 10 to 200 nm, and a coating porosity of <2%.

[0009] In one embodiment of the present invention, the base layer material is aluminum oxide or yttrium oxide, the base layer thickness is preferably 1-15 μm, more preferably 2-10 μm, the grain size is controlled in the range of 10-200 nm, preferably 50-150 nm, and the coating porosity is <2%.

[0010] In one embodiment of the present invention, the surface protective layer material includes at least one of yttrium oxide, yttrium fluoride, yttrium oxyfluoride or yttrium aluminum garnet, the surface layer thickness is 1~10 μm, the grain size is controlled at 10~50 nm, and the coating porosity is <1%.

[0011] In one embodiment of the present invention, the intermediate transition layer material is a mixture of a base layer material and a surface protective layer material, that is, a mixture of oxide ceramics and high-stability rare earth ceramics, the mass ratio of the oxide ceramics to the high-stability rare earth ceramics is 7:3~3:7, the thickness of the intermediate transition layer is 0.2~20 μm, preferably 1~15 μm, further preferably 2~10 μm, the grain size range is 10~200 nm, preferably 50-150 nm, and the coating porosity is <2%.

[0012] In one embodiment of the present invention, the intermediate transition layer material is a composite of a base layer material and a surface protection layer material, the composite is an oxide ceramic coated with a high-stability rare earth ceramic, and the particle size of the composite is 0.1-5 μm.

[0013] In the present invention, the base layer is made of oxide ceramic materials, such as aluminum oxide or yttrium oxide, which are mainly used to improve the bonding strength between the coating and the substrate while suppressing the concentration of interfacial stress. The middle layer is the mixing area of ​​the base layer and the surface layer material, and adopts a gradient structure design to achieve the transition between the materials, release the interfacial stress, and further improve the overall stability of the coating structure. The surface layer is a functional protective layer directly exposed to the plasma environment. The material is selected from high-stability rare earth ceramics, such as yttrium oxide, yttrium fluoride, yttrium oxyfluoride or yttrium aluminum garnet, which have high plasma stability and low etching rate.

[0014] In one embodiment of the present invention, the substrate includes but is not limited to any one of ceramics, metals, glass, and polymer plastics.

[0015] The present invention also discloses a method for preparing the above-mentioned plasma etching resistant nanostructured composite ceramic coating, comprising the following steps: (1) Mechanically polish the substrate surface to a surface roughness of Ra < 0.2 μm; (2) Oxide ceramic powder with a powder particle size of 0.1~5μm is selected, and a base layer is made on the substrate by vacuum cold spraying, and then heat treated; (3) A vacuum cold spray method is used to prepare an intermediate transition layer on the base layer obtained in step (2). The particle size of the transition layer powder ranges from 0.1 to 5 μm. After the transition layer is prepared, heat treatment is performed; (4) A surface protective layer is formed on the surface of the heat-treated transition layer obtained in step (3). The particle size of the surface protective layer powder ranges from 0.2 to 2 μm. After the surface protective layer is formed, heat treatment is performed.

[0016] In one embodiment of the present invention, the powder particle size in step (2) is preferably 0.2-3 μm, more preferably 0.5-2 μm, the thickness of the base layer is 0.2-20 μm, and the vacuum cold spraying process uses nitrogen or compressed air as the working gas, the gas flow rate is 5-50 L / min, the spraying distance is 3-20 mm, and the powder feeding rate is 0.1-5 g / min.

[0017] In one embodiment of the present invention, during the vacuum cold spraying in step (2), the gas flow rate is preferably 10-30 L / min, the spraying distance is preferably 5-15 mm, and the powder feeding rate is preferably 0.5-2 g / min.

[0018] In one embodiment of the present invention, the temperature of the heat treatment in step (2) is 400-1000°C, preferably 600-800°C, and the treatment time is 1-10 hours, preferably 2-6 hours.

[0019] In one embodiment of the present invention, the powder particle size of the intermediate transition layer in step (3) is preferably 0.2~2 μm, the thickness of the transition layer is 0.2~20 μm, the intermediate transition layer material is a mixture of a base layer material and a surface protective layer material, that is, a mixture of oxide ceramics and high-stability rare earth ceramics, the mass ratio of the oxide ceramics and the high-stability rare earth ceramics is 7:3~3:7, and the mixture is prepared by a mechanical mixing method.

[0020] In one embodiment of the present invention, the vacuum cold spraying process in step (3) uses nitrogen or compressed air as the working gas, the gas flow rate is 5-50 L / min, the spraying distance is 3-20 mm, and the powder feeding rate is 0.1-5 g / min.

[0021] In one embodiment of the present invention, during the vacuum cold spraying in step (3), the gas flow rate is preferably 10-30 L / min, the spraying distance is preferably 5-15 mm, and the powder feeding rate is preferably 0.5-2 g / min.

[0022] In one embodiment of the present invention, the temperature of the heat treatment in step (3) is 400-1000°C, preferably 600-800°C, and the treatment time is 1-10 hours, preferably 2-6 hours.

[0023] In one embodiment of the present invention, the powder particle size in step (4) is preferably 0.3-1 μm, the thickness of the surface protective layer is 1-10 μm, nitrogen or compressed air is used as the working gas in the vacuum cold spraying process, the gas flow rate is 5-50 L / min, the spraying distance is 3-20 mm, and the powder feeding rate is 0.1-5 g / min.

[0024] In one embodiment of the present invention, during the vacuum cold spraying in step (4), the gas flow rate is preferably 10-20 L / min, the spraying distance is preferably 5-10 mm, and the powder feeding rate is preferably 0.5-2 g / min.

[0025] In one embodiment of the present invention, the temperature of the heat treatment in step (3) is 400-1000°C, preferably 600-800°C, and the treatment time is 1-10 hours, preferably 1-3 hours.

[0026] The present invention also provides an application of the nanostructured composite ceramic coating in semiconductor devices.

[0027] In one embodiment of the present invention, the application includes use as a plasma etching protective coating.

[0028] Beneficial effects: (1) The present invention first deposits a layer of oxide ceramic with slightly larger porosity and larger grains on a substrate by using a vacuum cold spraying process, and then deposits a layer of high-stability rare earth ceramic layer with smaller porosity and smaller grain size on the surface of the oxide ceramic layer. The oxide ceramic with larger grains in the bottom layer can increase the bonding strength between the coating and the substrate, prevent the coating from falling off, and also help to increase the etching resistance of the coating; the rare earth ceramic with smaller grains in the surface coating can further increase the etching resistance of the coating.

[0029] (2) In order to further improve the bonding strength between the coatings, the present invention also adds an intermediate transition layer between the base layer and the surface protective coating. The transition layer is made of a mixture of the base layer powder and the surface protective coating powder. The preparation of the transition layer further increases the bonding strength between the base layer and the surface protective layer, and also further improves the etching resistance of the composite coating, so that the coating can achieve better etching resistance at a very low thickness, greatly reducing the preparation cost of the etching-resistant coating.

[0030] (3) The present invention first uses a vacuum cold spraying method to prepare a layer of oxide ceramic coating on the surface of the substrate as a base layer. After the base layer is prepared, a long period of heat treatment is performed to ensure that the coating has a high bonding strength to prevent the subsequent coating from falling off. Then, high-stability rare earth ceramics are prepared on the surface of the coating. When preparing high-stability rare earth ceramics, powder with a smaller particle size is selected for preparation. In this way, during the subsequent heat treatment, even if the grain size increases to a certain extent, it can still be ensured that the coating has a certain degree of etching resistance.

[0031] (4) When preparing the base layer and the intermediate transition layer, the present invention selects powder with a particle size of 0.1~5μm for vacuum cold spraying, the thickness of the intermediate layer and the transition layer is not higher than 20μm, the powder particle size of the surface protective coating is selected to be 0.2~2μm, and the thickness of the surface protective layer is not higher than 10μm. By further adjusting the material particle size and coating thickness, the bonding force between the coatings is further regulated, and the etching resistance of the composite coating is further improved.

[0032] (5) The three-layer structure of the present invention provides the coating with good stress distribution and interface matching performance, and the composite design effectively inhibits crack initiation and propagation; the nano-grain refinement significantly improves the density, thermal shock resistance, and micro-stability of the coating, effectively reducing the formation of particulate pollutants; the vacuum cold spraying process is low-temperature and non-melting, avoiding material structure degradation, and is suitable for heat-sensitive substrates and high-precision requirements; the material system is flexible and adjustable, adaptable to the protection needs under different process environments, and has the potential for industrial application.

[0033] (6) The present invention constructs a nanostructured plasma protection composite ceramic coating system and proposes an efficient, low-loss, and controllable preparation method, providing a new material solution for plasma etching protection in semiconductor device manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the surface morphology of the three-layer composite coating after etching in Example 1; Figure 2 This is the surface morphology of the yttrium oxide coating after etching in Comparative Example 1; Figure 3 The coating structure of the nanostructured plasma protective composite coating is shown, wherein 1 is a substrate, 2 is a composite coating, 21 is a base layer, 22 is an intermediate transition layer, and 23 is a surface protective layer. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0036] The plasma-etching-resistant nanostructured composite ceramic coating provided by the embodiment of the present invention is suitable for surface protection of inner wall components of a semiconductor etching equipment chamber.

[0037] The coating thicknesses in the Examples and Comparative Examples were measured by observing cross-sections of the coatings using a scanning electron microscope (SEM). Cross-section samples were prepared and 10 measurement points were selected at different locations along the coating. Data was then read and analyzed using image analysis software to determine the average thickness of each layer. Porosity was determined by obtaining SEM images of the coating cross-sections and using grayscale threshold segmentation to identify and quantify pore areas. The average porosity was then determined by calculating the ratio of black and white pixel areas. Grain size and coating bond strength were measured on three samples, and the results were averaged.

[0038] Example 1 A plasma-etching-resistant nanostructured composite ceramic coating 2 comprises a base layer 21, an intermediate transition layer 22, and a surface protective layer 23, which are sequentially prepared on the surface of an alumina substrate 1 by a vacuum cold spraying method. The base layer 21 is made of alumina, has a coating thickness of 5 μm, and a grain size of 120 nm. The intermediate transition layer 22 is a mixture of alumina and yttrium oxide in a ratio of 1:1, has a thickness of 5 μm, and a grain size of 120 nm. The surface protective layer 23 is made of yttrium oxide, has a thickness of 5 μm, and a grain size of 40 nm.

[0039] A method for preparing a plasma-etching-resistant nanostructured composite ceramic coating comprises the following steps: (1) Alumina powder with a particle size D50 of 1.2 μm was selected and a base layer with a thickness of 5 μm was prepared by vacuum cold spraying. Nitrogen was used as the working gas during vacuum cold spraying, the gas flow rate was 25 L / min, the spraying distance was 10 mm, and the powder feeding rate was 2 g / min. After the base layer was prepared, it was heat treated at a temperature of 800 °C for 5 h. (2) Alumina powder with a particle size of 1.2 μm and yttrium oxide powder with a particle size of 0.8 μm were mixed by roller ball milling. After ball milling for 1 h, a 5 μm thick intermediate transition layer was prepared by vacuum cold spraying. Nitrogen was used as the working gas during vacuum cold spraying, the gas flow rate was 25 L / min, the spraying distance was 10 mm, and the powder feeding rate was 2 g / min. After the base layer was prepared, it was heat treated at a temperature of 800 °C for 5 h. (3) Yttrium oxide powder with a particle size D50 of 0.8 μm was selected and a surface protective layer with a thickness of 5 μm was prepared by vacuum cold spraying. Nitrogen was used as the working gas during vacuum cold spraying, the gas flow rate was 15 L / min, the spraying distance was 8 mm, and the powder feeding rate was 1.2 g / min. After the base layer was prepared, it was heat treated at a temperature of 600 °C for 2 h.

[0040] After characterization and analysis, the results showed that the overall thickness of the composite coating was 15 μm, the porosity of the base layer and transition layer was 1.2%, the grain size was 120 nm, the porosity of the surface protective layer was 0.5%, the grain size was 40 nm, and the coating bonding strength was 22 MPa; after etching for 8 hours in a CF4 / O2 atmosphere, the coating was Figure 1 As shown, there are etched micro-pits on the surface of the composite coating, without obvious structural degradation, and the etching rate is about 2.1nm / min.

[0041] Example 2 A plasma-etching-resistant nanostructured composite ceramic coating comprises a primer layer, an intermediate transition layer, and a surface protective layer, which are sequentially prepared on the surface of a quartz glass substrate by a vacuum cold spraying method. The primer layer is aluminum oxide with a thickness of 0.5 μm and a grain size of 50 nm. The intermediate transition layer is a mixture of aluminum oxide and yttrium oxide in a mass ratio of 7:3, with a thickness of 1 μm and a grain size of 50 nm. The surface protective layer is yttrium oxide with a thickness of 0.5 μm and a grain size of 30 nm.

[0042] The preparation method of the composite ceramic coating comprises the following steps: (1) Alumina powder with a particle size D50 of 0.3 μm was selected and a base layer with a thickness of 0.5 μm was deposited on the surface of the alumina substrate by vacuum cold spraying. Nitrogen was used as the working gas during the spraying process, with a gas flow rate of 8 L / min, a spraying distance of 5 mm, and a powder feeding rate of 0.5 g / min. After spraying, heat treatment was performed at a temperature of 400°C for 3 h. (2) Alumina powder with a particle size D50 of 0.3 μm and yttrium fluoride powder with a D50 of 0.5 μm were mixed in a mass ratio of 7:3, and mixed by roller ball milling for 1 h. Subsequently, an intermediate transition layer with a thickness of 1 μm was prepared using the same process parameters as step (1); (3) Yttrium fluoride powder with a particle size D50 of 0.5 μm was used to prepare a surface protective layer with a thickness of 1 μm by vacuum cold spraying. The spraying conditions were nitrogen flow rate 10 L / min, spraying distance 10 mm, powder feeding rate 1.0 g / min, heat treatment temperature 400 °C, and time 1 h.

[0043] Characterization showed that the total thickness of the composite coating was 2.5 μm, the coating porosity was 0.9%, the grain size range was 30-50 nm, and the bonding strength was 23 MPa. After etching for 8 hours in CF4 / O2 plasma atmosphere, the etching rate was about 2.0 nm / min. Figure 1 As shown, there is no obvious structural peeling on the surface.

[0044] Example 3 A plasma-etching-resistant nanostructured composite ceramic coating comprises a primer layer, an intermediate transition layer, and a surface protective layer, which are sequentially prepared on the surface of an alumina substrate by a vacuum cold spraying method. The primer layer is made of yttrium oxide with a thickness of 15 μm and a grain size of 150 nm. The intermediate transition layer is a mixture of yttrium oxide and yttrium oxyfluoride in a mass ratio of 4:6, with a thickness of 18 μm and a grain size of 150 nm. The surface protective layer is made of yttrium oxyfluoride with a thickness of 10 μm and a grain size of 50 nm.

[0045] The preparation method of the composite ceramic coating comprises the following steps: (1) Yttrium oxide powder with a particle size D50 of 2.3 μm was selected and a base layer with a thickness of 15 μm was deposited on the surface of the aluminum alloy substrate by vacuum cold spraying. Nitrogen was used as the working gas during the spraying process, the gas flow rate was 35 L / min, the spraying distance was 15 mm, and the powder feeding rate was 2.5 g / min. After spraying, heat treatment was performed at a temperature of 800 °C for 6 h. (2) Yttrium oxide powder with a particle size D50 of 2.3 μm and yttrium oxyfluoride powder with a D50 of 0.8 μm were mixed in a mass ratio of 4:6 and mixed by roller ball milling for 1 h. Subsequently, an intermediate transition layer with a thickness of 18 μm was prepared using the same process parameters as step (1); (3) Yttrium fluoride oxyfluoride powder with a particle size D50 of 0.8 μm was used to prepare a surface protective layer with a thickness of 10 μm by vacuum cold spraying. The spraying conditions were nitrogen flow rate 15 L / min, spraying distance 10 mm, powder feeding rate 1.0 g / min, heat treatment temperature 600 °C, and time 3 h.

[0046] Characterization revealed that the resulting composite coating had a total thickness of 43 μm, a porosity of 1.9% and a grain size of 150 nm for the base and transition layers, a porosity of 0.8% and a grain size of 50 nm for the surface protective layer, and a bonding strength of 18 MPa. After etching for 8 hours in a CF₄ / O₂ plasma atmosphere, the etching rate was approximately 2.5 nm / min, with no noticeable surface structural delamination.

[0047] Example 4 The difference between Example 4 and Example 1 is that the base layer is a 30 μm thick aluminum oxide coating, the intermediate transition layer is a 30 μm thick aluminum oxide / yttrium oxide coating (mass ratio 1:1), and the surface protective layer is a 15 μm thick yttrium oxide.

[0048] Characterization revealed a total coating thickness of 45 μm. The base layer had a porosity of 1.8% and a grain size of 150 nm; the intermediate layer had a porosity of 2.2% and a grain size of 130 nm; and the surface protective layer had a porosity of 1.4% and a grain size of 80 nm. The composite coating's bond strength was measured at 12 MPa. Plasma etching tests (CF₄ / O₂ atmosphere, 8 hours of etching) revealed an etching rate of 3.1 nm / min, with minor cracks present within the coating.

[0049] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that only a surface protective yttrium oxide layer is formed on the substrate by using a vacuum cold spraying method.

[0050] High-purity yttrium oxide powder with a D50 particle size of 0.8 μm was used directly for spraying. The coating was prepared using vacuum cold spraying technology, with nitrogen as the working gas, a gas flow rate of 15 L / min, a spray distance of 8 mm, and a powder feeding rate of 1.2 g / min. The deposition thickness was 9 μm, the coating porosity was approximately 0.8%, the grain size was 80 nm, and the bonding strength was measured to be 9 MPa, which is lower than the composite sample (22 MPa). After plasma etching experiments (CF4 / O2 atmosphere, etching time 8 hours), it was found that etched micro-pits existed on the surface of the composite coating, and the etching rate was 3.6 nm / min. Figure 2 As shown, it can be observed that some coating has fallen off.

[0051] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the base layer is a 10 μm thick aluminum oxide coating, the intermediate transition layer is a 10 μm thick aluminum oxide / yttrium oxide coating (mass ratio 1:1), and the surface protective layer is a 5 μm thick yttrium oxide.

[0052] When the coating is prepared, no heat treatment is performed after each layer of coating is prepared.

[0053] Characterization revealed a total coating thickness of 25 μm, a base layer porosity of 2.1%, and a grain size of 80 nm; a transition layer porosity of 2.3%, and a grain size of 80 nm; and a surface protective layer porosity of 1.6%, with a grain size of 50 nm. The composite coating's bond strength was measured to be only 7 MPa, significantly lower than the 22 MPa achieved by the coating prepared using the optimal preparation parameters in Example 1. Before plasma etching, the composite coating exhibited partial delamination. However, after plasma etching (CF4 / O2 atmosphere, 8 hours of etching), the delamination became more widespread, resulting in a calculated etching rate of 5.8 nm / min.

[0054] Comparative Example 3 Comparative Example 3 differs from Example 1 in that the particle size of the aluminum oxide powder in the primer layer and transition layer is 2.5 μm, and the particle size of the yttrium oxide powder in the transition layer and surface protective layer is 2.2 μm. The thickness of the aluminum oxide layer is 5 μm, the intermediate transition layer is 5 μm, and the surface protective layer is 2 μm.

[0055] After testing, the total thickness of the coating is 12μm, the porosity of the base layer is 2.5%, and the grain size is 180 nm; the porosity of the intermediate transition layer is 2.8%, and the grain size is 150; the porosity of the surface protective layer is 1.8%, and the grain size is 120 nm. The bonding strength is only 3 MPa, the etching rate is as high as 12.5 nm / min, and obvious peeling and structural collapse occur on the surface.

[0056] Table 1 shows the experimental data for Examples 1-4 and Comparative Examples 1-3. As can be seen from Table 1, when the yttrium oxide coating is prepared solely by vacuum cold spraying, the plasma etching rate of a 9-μm-thick yttrium oxide coating is approximately 3.6 nm / min. While the coating exhibits moderate etching resistance, its bonding strength is low, and the coating may detach during etching. Experiments have shown that additional heat treatment of the yttrium oxide coating helps increase its bonding strength, but also increases the grain size, further reducing the coating's etching resistance.

[0057] In order to further improve the easy-to-fall-off performance of the yttrium oxide coating, experiments were conducted by designing the structure of the base layer, the intermediate transition layer and the surface protective layer. For example, in Comparative Example 2, the experiment found that simply adding aluminum oxide as the base layer and the transition layer structure did not improve the bonding strength of the coating, nor did it increase its etching resistance. Instead, the overall performance of the coating showed a significant decline.

[0058] The present invention first uses a vacuum cold spraying method to form a layer of oxide ceramic coating on the surface of the substrate as a base layer. After the base layer is formed, it is subjected to a long period of heat treatment to ensure that the coating has a high bonding strength and prevent the subsequent coating from falling off. Then, high-stability rare earth ceramics are formed on the surface of the coating. When forming the high-stability rare earth ceramics, powder with a smaller particle size is selected for production. In this way, even if the grain size increases to a certain extent during the subsequent heat treatment, it can still be ensured that the coating has a certain degree of etching resistance.

[0059] In order to further improve the bonding strength between the coatings, the present invention also adds an intermediate transition layer between the base layer and the surface protective coating. The transition layer is made of a mixture of the base layer powder and the surface protective coating powder. The preparation of the transition layer further increases the bonding strength between the base layer and the surface protective layer, and also further improves the etching resistance of the composite coating, so that the coating can achieve better etching resistance at a very low thickness, greatly reducing the preparation cost of the etching-resistant coating.

[0060] The particle size of the powder material of the base layer and the surface protective coating also has a great influence on the performance of the composite coating. It can be seen from the experimental data of the embodiment and comparative example 3 that when the powder particle size used in the surface composite coating is greater than 1.5μm, or even greater than 2μm, the bonding strength and etching resistance of the coating are significantly deteriorated, which is far from meeting the requirements.

[0061] In addition, the thickness of each layer and the overall thickness of the coating will significantly affect the bonding strength and etching resistance of the composite coating. It can be seen from Examples 1 and 4 that when the thickness of the base layer and the transition layer increases to more than 20 μm, and the thickness of the surface protective layer increases to more than 10 μm, the bonding force between the coatings tends to decrease. Compared with Example 1, although Example 4 also adopts a three-layer structure, as the thickness of the composite coating increases, problems such as high coating porosity and coarse grains appear, resulting in the coating bonding strength and etching resistance being significantly lower than that of Example 1, and cracks begin to appear inside the coating of Example 4.

[0062] Table 1 Comparison of composite coating results between the embodiment and the comparative example

[0063] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A plasma-etching-resistant nanostructured composite ceramic coating, characterized in that: The invention comprises a base layer and a surface protective layer deposited sequentially on a substrate by a vacuum cold spraying method. The material of the base layer is oxide ceramic, and the material of the surface protective layer is high-stability rare earth ceramic. The thickness of the base layer is 0.2-20 μm, the grain size is 10-200 nm, and the coating porosity is less than 2%. The thickness of the surface protective layer is 1-10 μm, the grain size is 10-50 nm, and the coating porosity is less than 1%.

2. The nanostructured composite ceramic coating according to claim 1, wherein: An intermediate transition layer is also provided between the primer layer and the surface protective layer. The intermediate transition layer is a composite of oxide ceramics and high-stability rare earth ceramics. The intermediate transition layer has a thickness of 0.2 to 20 μm, a grain size range of 10 to 200 nm, and a coating porosity of <2%.

3. The nanostructured composite ceramic coating according to claim 1 or 2, wherein: The material of the base layer is aluminum oxide or yttrium oxide, the thickness of the base layer is 2~10 μm, the grain size is controlled at 50~150 nm, the coating porosity is <2%, and the material of the surface protective layer includes at least one of yttrium oxide, yttrium fluoride, yttrium oxyfluoride or yttrium aluminum garnet, and the thickness of the surface protective layer is 1~10 μm.

4. The nanostructured composite ceramic coating according to claim 2, wherein: The material of the intermediate transition layer is a mixture of oxide ceramics and high-stability rare earth ceramics, wherein the mass ratio of oxide ceramics to high-stability rare earth ceramics is 7:3~3:7, the thickness of the intermediate transition layer is 2~10 μm, the grain size range is 50~150 nm, and the coating porosity is <2%.

5. The nanostructured composite ceramic coating according to claim 1 or 2, characterized in that: The material of the substrate includes but is not limited to any one of ceramics, metals, glass, and polymer plastics.

6. The method for preparing a nanostructured composite ceramic coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Mechanically polish the substrate surface to a surface roughness of Ra < 0.2 μm; (2) Oxide ceramic powder with a powder particle size of 0.1~5μm is selected, and a base layer is made on the substrate by vacuum cold spraying, and then heat treated; (3) A vacuum cold spray method is used to prepare an intermediate transition layer on the base layer obtained in step (2). The particle size of the transition layer powder ranges from 0.1 to 5 μm. After the transition layer is prepared, heat treatment is performed; (4) A surface protective layer is formed on the surface of the heat-treated transition layer obtained in step (3). The particle size of the surface protective layer powder ranges from 0.2 to 2 μm. After the surface protective layer is formed, heat treatment is performed.

7. The preparation method according to claim 6, wherein The powder particle size of step (2) is 0.2~3 μm, the thickness of the base layer is 0.2~20 μm, nitrogen or compressed air is used as the working gas in the vacuum cold spraying process, the gas flow rate is 5~50 L / min, the spraying distance is 3~20 mm, the powder feeding rate is 0.1~5 g / min, the heat treatment temperature is 400~1000℃, and the treatment time is 1~10h.

8. The preparation method according to claim 6, wherein In step (3), the powder particle size of the intermediate transition layer is 0.2~2 μm, the thickness of the intermediate transition layer is 0.2~20 μm, nitrogen or compressed air is used as the working gas in the vacuum cold spraying process, the gas flow rate is 5~50 L / min, the spraying distance is 3~20 mm, the powder feeding rate is 0.1~5 g / min, the heat treatment temperature is 400~1000 °C, and the treatment time is 1~10 h.

9. The preparation method according to claim 6, wherein The powder particle size of step (4) is 0.3~1 μm, the thickness of the surface protective layer is 1~10 μm, nitrogen or compressed air is used as the working gas in the vacuum cold spraying process, the gas flow rate is 5~50 L / min, the spraying distance is 3~20 mm, the powder feeding rate is 0.1~5 g / min, the heat treatment temperature is 400~1000℃, and the treatment time is 1~10h.

10. Use of the nanostructured composite ceramic coating according to any one of claims 1 to 5 as a plasma etching protective coating in a semiconductor device.

Images